元素氧化态列表 (Chinese Wikipedia)

Analysis of information sources in references of the Wikipedia article "元素氧化态列表" in Chinese language version.

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Be(I)已在一氫化鈹（英语：Beryllium monohydride）（BeH）中觀察到，參見：Shayesteh, A.; Tereszchuk, K.; Bernath, P. F.; Colin, R. Infrared Emission Spectra of BeH and BeD (PDF). J. Chem. Phys. 2003, 118 (3): 1158 [2007-12-10]. Bibcode:2003JChPh.118.1158S. doi:10.1063/1.1528606. （原始内容 (PDF)存档于2007-12-02）. and in [(CAAC)₂Be]^+• [CAAC = cyclic (alkyl)(amino)carbene], see Wang, Guocang; Walley, Jacob E.; Dickie, Diane E.; Pan, Sudip; Frenking, Gernot; Gilliard Jr., Robert G. A Stable, Crystalline Beryllium Radical Cation. J. Am. Chem. Soc. 2020, 142 (10): 4560–4 [2020-11-17]. PMID 32088963. S2CID 211262005. doi:10.1021/jacs.9b13777. （原始内容存档于2022-09-24）.
已知含有氦原子的SF₆⁺團簇中有氟(0)原子作為配基，參見：Albertini, Simon; Bergmeister, Stefan; Laimer, Felix; Martini, Paul; Gruber, Elisabeth; Zappa, Fabio; Ončák, Milan; Scheier, Paul; Echt, Olof. SF 6 + : Stabilizing Transient Ions in Helium Nanodroplets. The Journal of Physical Chemistry Letters. 2021-04-22, 12 (17): 4112–4117 [2023-05-28]. ISSN 1948-7185. PMC 8154854 . PMID 33886323. doi:10.1021/acs.jpclett.1c01024 . （原始内容存档于2022-09-24）（英语）.
Br(II)已知存在於一氧化溴自由基中，參見：[4] （页面存档备份，存于互联网档案馆）
SmB₆^-團簇陰離子已被報告，其中含有罕見的+1態釤，參見：Paul, J. Robinson; Xinxing, Zhang; Tyrel, McQueen; Kit, H. Bowen; Anastassia, N. Alexandrova. SmB₆^– Cluster Anion: Covalency Involving f Orbitals. J. Phys. Chem. A 2017, 121, 8, 1849–1854. 2017, 121 (8): 1849–1854 [2023-05-28]. （原始内容存档于2022-09-25）. .
Langmuir, Irving. THE ARRANGEMENT OF ELECTRONS IN ATOMS AND MOLECULES.. Journal of the American Chemical Society. 1919-06, 41 (6): 868–934 [2022-03-25]. ISSN 0002-7863. doi:10.1021/ja02227a002. （原始内容存档于2020-05-09）（英语）.

cen.acs.org

所有鑭系元素（鑭至鎦）的+2氧化態均已在其二鹵化物和鹼土金屬二鹵化物形成的稀固溶體中（參閱：Holleman, Arnold Frederik; Wiberg, Egon, Wiberg, Nils , 编, Inorganic Chemistry, 由Eagleson, Mary; Brewer, William翻译, San Diego/Berlin: Academic Press/De Gruyter, 2001, ISBN 0-12-352651-5 ，鑭、釓、鎦除外）以及其有機金屬分子錯合物中（鉕除外）觀察到，參見：Lanthanides Topple Assumptions （页面存档备份，存于互联网档案馆） and Meyer, G. All the Lanthanides Do It and Even Uranium Does Oxidation State +2. Angewandte Chemie International Edition. 2014, 53 (14): 3550–51. PMID 24616202. doi:10.1002/anie.201311325. 。此外，雖然所有鑭系元素皆形成二氫化物（LnH₂）、二碳化物（LnC₂）、一硫化物（LnS）、一硒化物（LnSe）和一碲化物（LnTe），但對於大多數鑭系元素，這些化合物中的鑭系離子實為+3態，伴隨著離域至導帶的電子，例如：Ln³⁺(H⁻)₂(e⁻)。

archive.org

Ge(-1)、Ge(-2)和Ge(-3)已在鍺化物中觀察到，參見Holleman, Arnold F.; Wiberg, Egon; Wiberg, Nils. Germanium. Lehrbuch der Anorganischen Chemie 101. Walter de Gruyter. 1995: 953–959. ISBN 978-3-11-012641-9 （德语）.
Zr(−1)曾被報告存在於[Zr(bipy)₃]⁻中（參見 Greenwood, N. N.; Earnshaw, A. Chemistry of the Elements 2nd. Oxford:Butterworth-Heinemann. 1997: 960. ISBN 0-7506-3365-4. 及 Holleman, Arnold F.; Wiberg, Egon; Wiberg, Nils. Zirconium. Lehrbuch der Anorganischen Chemie 101. Walter de Gruyter. 1995: 1413. ISBN 978-3-11-012641-9 （德语）. ）, 但後來被證明是Zr(+4)，參見：Bowman, A. C.; England, J.; Sprouls, S.; Weihemüller, T.; Wieghardt, K. Electronic structures of homoleptic [tris(2,2'-bipyridine)M]n complexes of the early transition metals (M = Sc, Y, Ti, Zr, Hf, V, Nb, Ta; n = 1+, 0, 1-, 2-, 3-): an experimental and density functional theoretical study. Inorganic Chemistry. 2013, 52 (4): 2242–56. PMID 23387926. doi:10.1021/ic302799s.
Nb(I)和Ta(I)分別存在於CpNb(CO)₄和CpTa(CO)₄中，參見：Holleman, Arnold F.; Wiberg, Egon; Wiberg, Nils. Tantal. Lehrbuch der Anorganischen Chemie 101. Walter de Gruyter. 1995: 1430. ISBN 978-3-11-012641-9 （德语）. and King, R. Bruce. Transition-Metal Organometallic Chemistry: An Introduction. Academic Press. 1969: 11. ISBN 978-0-32-315996-8.
I(IV)已在二氧化碘（IO₂）中觀察到，參見：Pauling, Linus. Oxygen Compounds of Nonmetallic Elements. General Chemistry 3rd. Dover Publications, Inc. 1988: 259. ISBN 978-0-486-65622-9.
Xe(I)曾被報告存在於六氟合鉑酸氙及六氟合銠酸氙中（參閱 Pauling, Linus. General Chemistry 3rd. Dover Publications, Inc. 1988: 250. ISBN 978-0-486-65622-9. ）, 然而後來的研究發現這些化合物中所含的是Xe(II)。
Pb(−2)已在BaPb中觀察到，參見：Ferro, Riccardo. Nicholas C. Norman , 编. Intermetallic Chemistry. Elsevier. 2008: 505. ISBN 978-0-08-044099-6. and Todorov, Iliya; Sevov, Slavi C. Heavy-Metal Aromatic Rings: Cyclopentadienyl Anion Analogues Sn₅⁶⁻ and Pb₅⁶⁻ in the Zintl Phases Na₈BaPb₆, Na₈BaSn₆, and Na₈EuSn₆. Inorganic Chemistry. 2004, 43 (20): 6490–94. doi:10.1021/ic000333x.
Peterson, J. R.; Hobart, D. E. The Chemistry of Berkelium. Emeléus, Harry Julius (编). Advances in inorganic chemistry and radiochemistry 28. Academic Press. 1984: 29–64. ISBN 978-0-12-023628-2. doi:10.1016/S0898-8838(08)60204-4.

arxiv.org

已合成出在高壓下熱力學穩定的氦化鈉（(Na⁺)₂He(e^-)₂），參見：Dong, Xiao; Oganov, Artem R.; Goncharov, Alexander F.; Stavrou, Elissaios; Lobanov, Sergey; Saleh, Gabriele; Qian, Guang-Rui; Zhu, Qiang; Gatti, Carlo; Deringer, Volker L.; Dronskowski, Richard; Zhou, Xiang-Feng; Prakapenka, Vitali B.; Konôpková, Zuzana; Popov, Ivan A.; Boldyrev, Alexander I.; Wang, Hui-Tian. A stable compound of helium and sodium at high pressure. Nature Chemistry. 6 February 2017, 9 (5): 440–445. Bibcode:2017NatCh...9..440D. PMID 28430195. S2CID 20459726. arXiv:1309.3827 . doi:10.1038/nchem.2716.
實驗表明，氯化鈉在高壓下存在幾種不尋常的化學計量，例如Na₃Cl，其中包含一層Na(0)原子，參見：Zhang, W.; Oganov, A. R.; Goncharov, A. F.; Zhu, Q.; Boulfelfel, S. E.; Lyakhov, A. O.; Stavrou, E.; Somayazulu, M.; Prakapenka, V. B.; Konôpková, Z. Unexpected Stable Stoichiometries of Sodium Chlorides. Science. 2013, 342 (6165): 1502–1505. Bibcode:2013Sci...342.1502Z. PMID 24357316. S2CID 15298372. arXiv:1310.7674 . doi:10.1126/science.1244989.

books.google.com

B(−1)已在二硼化鎂（MgB₂）中觀察到，參見：Keeler, James; Wothers, Peter. Chemical Structure and Reactivity: An Integrated Approach. Oxford University Press. 2014 [2023-05-28]. ISBN 9780199604135. （原始内容存档于2022-09-22）.
Ti(−2)、V(−3)、Cr(−4)、Co(−3)、Zr(−2)、Nb(−3)、Mo(−4)、Ru(−2)、Rh( −3)、Hf(−2)、Ta(−3)和W(−4)存在於陰離子二元金屬羰基錯合物中，參見：[1] （页面存档备份，存于互联网档案馆）, p. 4 (in German); [2], pp. 97–100; [3], p. 239
In(−2)已在Na₂In中觀察到，參見：[5], p. 69.
Greenwood and Earnshaw報告了Rn(IV)，但其存在尚未獲得證實，參閱：Sykes, A. G. Recent Advances in Noble-Gas Chemistry. Advances in Inorganic Chemistry 46. Academic Press. 1998: 91–93 [22 November 2012]. ISBN 978-0-12-023646-6.
Rn(VI)已知存在於三氧化氡（RnO₃），參見：Sykes, A. G. Recent Advances in Noble-Gas Chemistry. Advances in Inorganic Chemistry 46. Academic Press. 1998: 91–93 [22 November 2012]. ISBN 978-0-12-023646-6.
U(I)已在一氟化鈾（UF）及一氯化鈾（UCl）中觀察到，參見：Sykes, A. G. Compounds of Thorium and Uranium. Advances in Inorganic Chemistry 34. Academic Press. 1990: 87–88 [22 March 2015]. ISBN 978-0-12-023634-3.
Peterson, J. R.; Hobart, D. E. The Chemistry of Berkelium. Emeléus, Harry Julius (编). Advances in inorganic chemistry and radiochemistry 28. Academic Press. 1984: 29–64. ISBN 978-0-12-023628-2. doi:10.1016/S0898-8838(08)60204-4.

caltech.edu

authors.library.caltech.edu

Cu(0)已在Cu(tris[2-(diisopropylphosphino)-phenyl]borane)中觀察到，參見：Moret, Marc-Etienne; Zhang, Limei; Peters, Jonas C. A Polar Copper–Boron One-Electron σ-Bond. J. Am. Chem. Soc. 2013, 135 (10): 3792–3795 [2023-05-28]. PMID 23418750. doi:10.1021/ja4006578. （原始内容存档于2022-10-07）.

cenmag.org

2014.cenmag.org

Ir(VII)已在[(η²-O₂)IrO₂]⁺中觀察到，參見：C&EN: Iridium dressed to the nines （页面存档备份，存于互联网档案馆）.

chemie-master.de

Am(VII)已在AmO−
5中觀察到，參見：Americium （页面存档备份，存于互联网档案馆）, Das Periodensystem der Elemente für den Schulgebrauch (The periodic table of elements for schools) chemie-master.de (in German), Retrieved 28 November 2010 and Greenwood, N. N.; Earnshaw, A. Chemistry of the Elements 2nd. Oxford:Butterworth-Heinemann. 1997: 1265. ISBN 0-7506-3365-4.

chemistryviews.org

Be(0)已被觀察到，參見：Beryllium(0) Complex Found. Chemistry Europe（英语：Chemistry Europe）. 13 June 2016 [2023-05-28]. （原始内容存档于2020-10-28）.
New Type of Zero-Valent Tin Compound. Chemistry Europe（英语：Chemistry Europe）. 27 August 2016 [2023-05-28]. （原始内容存档于2021-01-26）.

d-nb.info

B(−5)已在Al₃BC中觀察到，參見：Schroeder, Melanie. Eigenschaften von borreichen Boriden und Scandium-Aluminium-Oxid-Carbiden. : 139 [2023-05-28]. （原始内容存档于2020-08-06）（德语）.
Ti(−2)、V(−3)、Cr(−4)、Co(−3)、Zr(−2)、Nb(−3)、Mo(−4)、Ru(−2)、Rh( −3)、Hf(−2)、Ta(−3)和W(−4)存在於陰離子二元金屬羰基錯合物中，參見：[1] （页面存档备份，存于互联网档案馆）, p. 4 (in German); [2], pp. 97–100; [3], p. 239
Bi(−2)及Bi(−1)存在於津特耳相中，例如(Ca²⁺)₂₂[Bi₄]⁴⁻([Bi₂]⁴⁻)₄[Bi³⁻]₈；參閱：Ponou, Siméon. Germanides, Germanide-Tungstate Double Salts and Substitution Effects in Zintl Phases. Technische Universität München. Lehrstuhl für Anorganische Chemie mit Schwerpunkt Neue Materialien. 2006: 68 [2023-05-28]. （原始内容存档于2015-02-21）.

doi.org

已合成出在高壓下熱力學穩定的氦化鈉（(Na⁺)₂He(e^-)₂），參見：Dong, Xiao; Oganov, Artem R.; Goncharov, Alexander F.; Stavrou, Elissaios; Lobanov, Sergey; Saleh, Gabriele; Qian, Guang-Rui; Zhu, Qiang; Gatti, Carlo; Deringer, Volker L.; Dronskowski, Richard; Zhou, Xiang-Feng; Prakapenka, Vitali B.; Konôpková, Zuzana; Popov, Ivan A.; Boldyrev, Alexander I.; Wang, Hui-Tian. A stable compound of helium and sodium at high pressure. Nature Chemistry. 6 February 2017, 9 (5): 440–445. Bibcode:2017NatCh...9..440D. PMID 28430195. S2CID 20459726. arXiv:1309.3827 . doi:10.1038/nchem.2716.
Li(0)原子已在多種氯化鋰小團簇中觀察到，參見：Milovanović, Milan; Veličković, Suzana; Veljkovićb, Filip; Jerosimić, Stanka. Structure and stability of small lithium-chloride Li_nCl_m^(0,1+) (n ≥ m, n = 1–6, m = 1–3) clusters. Physical Chemistry Chemical Physics. October 30, 2017, (45) [2023-05-28]. doi:10.1039/C7CP04181K. （原始内容存档于2022-09-22）.
Be(I)已在一氫化鈹（英语：Beryllium monohydride）（BeH）中觀察到，參見：Shayesteh, A.; Tereszchuk, K.; Bernath, P. F.; Colin, R. Infrared Emission Spectra of BeH and BeD (PDF). J. Chem. Phys. 2003, 118 (3): 1158 [2007-12-10]. Bibcode:2003JChPh.118.1158S. doi:10.1063/1.1528606. （原始内容 (PDF)存档于2007-12-02）. and in [(CAAC)₂Be]^+• [CAAC = cyclic (alkyl)(amino)carbene], see Wang, Guocang; Walley, Jacob E.; Dickie, Diane E.; Pan, Sudip; Frenking, Gernot; Gilliard Jr., Robert G. A Stable, Crystalline Beryllium Radical Cation. J. Am. Chem. Soc. 2020, 142 (10): 4560–4 [2020-11-17]. PMID 32088963. S2CID 211262005. doi:10.1021/jacs.9b13777. （原始内容存档于2022-09-24）.
B(0)已在雙硼炔（英语：diboryne）中觀察到，參見：Braunschweig, H.; Dewhurst, R. D.; Hammond, K.; Mies, J.; Radacki, K.; Vargas, A. Ambient-Temperature Isolation of a Compound with a Boron-Boron Triple Bond. Science. 2012, 336 (6087): 1420–2. Bibcode:2012Sci...336.1420B. PMID 22700924. S2CID 206540959. doi:10.1126/science.1221138.
四唑環中有一對以雙鍵鍵結、氧化態為0的氮原子。母體1-H-四唑（CH₂N₄）的合成過程參見Ronald A. Henry and William G. Finnegan, "An Improved Procedure for the Deamination of 5-Aminotetrazole", _J. Am. Chem. Soc._ (1954), 76, 1, 290–291, https://doi.org/10.1021/ja01630a086.
七氟化金實際上是五氟化金與氟分子（F₂）形成的配合物。Himmel, Daniel; Riedel, Sebastian. After 20 Years, Theoretical Evidence That 'AuF₇' Is Actually AuF₅•F₂. Inorganic Chemistry. 2007, 46 (13): 5338–5342. PMID 17511450. doi:10.1021/ic700431s.
已知含有氦原子的SF₆⁺團簇中有氟(0)原子作為配基，參見：Albertini, Simon; Bergmeister, Stefan; Laimer, Felix; Martini, Paul; Gruber, Elisabeth; Zappa, Fabio; Ončák, Milan; Scheier, Paul; Echt, Olof. SF 6 + : Stabilizing Transient Ions in Helium Nanodroplets. The Journal of Physical Chemistry Letters. 2021-04-22, 12 (17): 4112–4117 [2023-05-28]. ISSN 1948-7185. PMC 8154854 . PMID 33886323. doi:10.1021/acs.jpclett.1c01024 . （原始内容存档于2022-09-24）（英语）.
Ne(0)已在Cr(CO)₅Ne中觀察到，參見：Perutz, Robin N.; Turner, James J. Photochemistry of the Group 6 hexacarbonyls in low-temperature matrices. III. Interaction of the pentacarbonyls with noble gases and other matrices. Journal of the American Chemical Society. August 1975, 97 (17): 4791–4800. doi:10.1021/ja00850a001.
實驗表明，氯化鈉在高壓下存在幾種不尋常的化學計量，例如Na₃Cl，其中包含一層Na(0)原子，參見：Zhang, W.; Oganov, A. R.; Goncharov, A. F.; Zhu, Q.; Boulfelfel, S. E.; Lyakhov, A. O.; Stavrou, E.; Somayazulu, M.; Prakapenka, V. B.; Konôpková, Z. Unexpected Stable Stoichiometries of Sodium Chlorides. Science. 2013, 342 (6165): 1502–1505. Bibcode:2013Sci...342.1502Z. PMID 24357316. S2CID 15298372. arXiv:1310.7674 . doi:10.1126/science.1244989.
Mg(0)已在Na₂Mg₂²⁺團簇與龐大有機配體配位形成的絡合物中觀察到，參見：Rösch, B.; Gentner, T. X.; Eyselein, J.; Langer, J.; Elsen, H.; Li, W.; Harder, S. Strongly reducing magnesium(0) complexes. Nature. 2021, 592 (7856): 717–721. Bibcode:2021Natur.592..717R. PMID 33911274. S2CID 233447380. doi:10.1038/s41586-021-03401-w
含有Mg(I)的低價鎂化合物已使用大陰離子配體製得，參見：Green, S. P.; Jones C.; Stasch A. Stable Magnesium(I) Compounds with Mg-Mg Bonds. Science. December 2007, 318 (5857): 1754–1757. Bibcode:2007Sci...318.1754G. PMID 17991827. S2CID 40657565. doi:10.1126/science.1150856.
Al(−2)已在Sr₁₄[Al₄]₂[Ge]₃中觀察到，參見：Wemdorff, Marco; Röhr, Caroline. Sr₁₄[Al₄]₂[Ge]₃: Eine Zintl-Phase mit isolierten [Ge]^4–- und [Al₄]^8–-Anionen / Sr₁₄[Al₄]₂[Ge]₃: A Zintl Phase with Isolated [Ge]^4–- and [Al₄]^8– Anions. Zeitschrift für Naturforschung B. 2007, 62 (10): 1227. S2CID 94972243. doi:10.1515/znb-2007-1001 （德语）.
不穩定的Al(0)羰基配合物已在三甲基鋁（Al₂(CH₃)₆）與一氧化碳的反應中檢測到，參見：Sanchez, Ramiro; Arrington, Caleb; Arrington Jr., C. A. Reaction of trimethylaluminum with carbon monoxide in low-temperature matrixes. American Chemical Society. December 1, 1989, 111 (25): 9110-9111. doi:10.1021/ja00207a023.
Al(II)已在一氧化鋁（AlO）中觀察到，參見：Tyte, D.C. Red (B2Π–A2σ) Band System of Aluminium Monoxide. Nature. 1964, 202 (4930): 383–384. Bibcode:1964Natur.202..383T. S2CID 4163250. doi:10.1038/202383a0 , and in dialanes (R₂Al—AlR₂); see Uhl, Werner. Organoelement Compounds Possessing Al—Al, Ga—Ga, In—In, and Tl—Tl Single Bonds. Advances in Organometallic Chemistry. 2004, 51: 53–108. doi:10.1016/S0065-3055(03)51002-4.
P(0)已被觀察到，參見：Wang, Yuzhong; Xie, Yaoming; Wei, Pingrong; King, R. Bruce; Schaefer, Iii; Schleyer, Paul v. R.; Robinson, Gregory H. Carbene-Stabilized Diphosphorus. Journal of the American Chemical Society. 2008, 130 (45): 14970–1. PMID 18937460. doi:10.1021/ja807828t.
Cl₂O₆⇌2ClO₃反應的化學平衡曾被Greenwood & Earnshaw提及，但已被駁回。參見：Lopez, Maria; Juan E. Sicre. Physicochemical properties of chlorine oxides. 1. Composition, ultraviolet spectrum, and kinetics of the thermolysis of gaseous dichlorine hexoxide. J. Phys. Chem. 1990, 94 (9): 3860–3863. doi:10.1021/j100372a094. , and Cl₂O₆ is actually chlorine(V,VII) oxide. However, ClO₃ has been observed, see Grothe, Hinrich; Willner, Helge. Chlorine Trioxide: Spectroscopic Properties, Molecular Structure, and Photochemical Behavior. Angew. Chem. Int. Ed. 1994, 33 (14): 1482–1484. doi:10.1002/anie.199414821.
Ar(0)已在氟氬化氫（HArF）及ArCF₂²⁺中觀察到，參見：Lockyear, J.F.; Douglas, K.; Price, S.D.; Karwowska, M.; et al. Generation of the ArCF₂²⁺ Dication. Journal of Physical Chemistry Letters. 2010, 1: 358. doi:10.1021/jz900274p.
已在以氖作為基質的隔離（英语：Matrix isolation）下觀察到鈣、鍶、鋇的八羰基配合物，但尚不清楚這些是否為其0價態配合物，因為計算結果否定了配合物中金屬原子和配體形成共價鍵或離子鍵與否，參見：Wu, X.; Zhao, L.; Jin, J.; Pan, S.; Li, W.; Jin, X.; Wang, G.; Zhou, M.; Frenking, G. Observation of alkaline earth complexes M(CO)8 (M = Ca, Sr, or Ba) that mimic transition metals. Science. 2018, 361 (6405): 912–916. Bibcode:2018Sci...361..912W. PMID 30166489. S2CID 52131470. doi:10.1126/science.aau0839
Ca(I)已被觀察到，參見：Krieck, Sven; Görls, Helmar; Westerhausen, Matthias. Mechanistic Elucidation of the Formation of the Inverse Ca(I) Sandwich Complex [(thf)₃Ca(μ-C₆H₃-1,3,5-Ph₃)Ca(thf)₃] and Stability of Aryl-Substituted Phenylcalcium Complexes. Journal of the American Chemical Society. 2010, 132 (35): 12492–501. PMID 20718434. doi:10.1021/ja105534w.
Sc(0)已被觀察到，參見：F. Geoffrey N. Cloke; Karl Khan & Robin N. Perutz. η-Arene complexes of scandium(0) and scandium(II). J. Chem. Soc., Chem. Commun. 1991, (19): 1372–1373. doi:10.1039/C39910001372.
Sc(I)已被觀察到，參見：Polly L. Arnold; F. Geoffrey; N. Cloke; Peter B. Hitchcock & John F. Nixon. The First Example of a Formal Scandium(I) Complex: Synthesis and Molecular Structure of a 22-Electron Scandium Triple Decker Incorporating the Novel 1,3,5-Triphosphabenzene Ring. J. Am. Chem. Soc. 1996, 118 (32): 7630–7631. doi:10.1021/ja961253o.
Sc(II)已被觀察到，參見：Woen, David H.; Chen, Guo P.; Ziller, Joseph W.; Boyle, Timothy J.; Furche, Filipp; Evans, William J. Solution Synthesis, Structure, and CO Reduction Reactivity of a Scandium(II) Complex. Angewandte Chemie International Edition. January 2017, 56 (8): 2050–2053. PMID 28097771. doi:10.1002/anie.201611758.
Ti(−1)最初被報告存在於[Ti(bipy)₃]⁻ 中，但後來證明其為Ti(+3)，參見Bowman, A. C.; England, J.; Sprouls, S.; Weihemüller, T.; Wieghardt, K. Electronic structures of homoleptic [tris(2,2'-bipyridine)M]n complexes of the early transition metals (M = Sc, Y, Ti, Zr, Hf, V, Nb, Ta; n = 1+, 0, 1-, 2-, 3-): an experimental and density functional theoretical study. Inorganic Chemistry. 2013, 52 (4): 2242–56. PMID 23387926. doi:10.1021/ic302799s. 不過，Ti(−1)被發現存在於[Ti(η-C₆H₆]⁻和[Ti(η-C₆H₅CH₃)]⁻中, 參見：Bandy, J. A.; Berry, A.; Green, M. L. H.; Perutz, R. N.; Prout, K.; Verpeautz, J.-N. Synthesis of anionic sandwich compounds: [Ti(η-C₆H₅R)₂]^– and the crystal structure of [K(18-crown-6)(µ-H)Mo(η-C₅H₅)₂]. Inorganic Chemistry. 1984, 52 (4): 729–731. doi:10.1039/C39840000729.
Ti(I)已在[Ti(η⁶-1,3,5-C₆H₃ⁱPr₃)2][BAr₄] (Ar = C₆H₅, p-C₆H₄F, 3,5-C₆H₃(CF₃)₂)中觀察到，參見：Calderazzo, Fausto; Ferri, Isabella; Pampaloni, Guido; Englert, Ulli; Green, Malcolm L. H. Synthesis of [Ti(η⁶-1,3,5-C₆H₃iPr₃)₂][BAr₄] (Ar = C₆H₅, p-C₆H₄F, 3,5-C₆H₃(CF₃)₂), the First Titanium(I) Derivatives. Organometallics. 1997, 16 (14): 3100–3101. doi:10.1021/om970155o.
Jilek, Robert E.; Tripepi, Giovanna; Urnezius, Eugenijus; Brennessel, William W.; Young, Victor G. Jr.; Ellis, John E. Zerovalent titanium–sulfur complexes. Novel dithiocarbamato derivatives of Ti(CO)₆: [Ti(CO)₄(S₂CNR₂)]⁻. Chem. Commun. 2007, (25): 2639–2641. PMID 17579764. doi:10.1039/B700808B.
Fe(VII)已在[FeO₄]⁻中觀察到，參見：Lu, Jun-Bo; Jian, Jiwen; Huang, Wei; Lin, Hailu; Zhou, Mingfei. Experimental and theoretical identification of the Fe(VII) oxidation state in FeO₄⁻. Physical Chemistry Chemical Physics. 2016, 18 (45): 31125–31131. Bibcode:2016PCCP...1831125L. PMID 27812577. doi:10.1039/C6CP06753K.
Fe(VIII)已被報告，參見：Yurii D. Perfiliev; Virender K. Sharma. Higher Oxidation States of Iron in Solid State: Synthesis and Their Mössbauer Characterization – Ferrates – ACS Symposium Series (ACS Publications). Platinum Metals Review. 2008, 48 (4): 157–158. doi:10.1595/147106704X10801. 然而，其存在與否一直有所爭議。
Fe(−4)、Ru(−4)和Os(−4)已在含有八面體配合物[MIn_6−xSn_x]的富金屬化合物中觀察到；Pt(−3)（以二聚體陰離子[Pt–Pt]⁶⁻的形式）、Cu(−2)、Zn(−2)、Ag(−2)、Cd(−2)、Au(−2)和Hg(−2)（以二聚體和單體陰離子之形式；Zn、Cd、Hg的二聚體離子最初被報告為[T–T]²⁻的形式、但後來的研究顯示所有這些元素的二聚體陰離子皆為[T–T]⁴⁻形式）已在下列化合物中觀察到：La₂Pt₂In、La₂Cu₂In、Ca₅Au₃、Ca₅Ag₃、Ca₅Hg₃、Sr₅Cd₃、Ca₅Zn₃（結構為(AE²⁺)₅(T–T)⁴⁻T^{2 −}⋅4e⁻）、Yb₃Ag₂、Ca₅Au₄和Ca₃Hg₂；Au(-3)已在ScAuSn及其他18電子的半赫斯勒化合物（英语：Heusler compound）中觀察到。參見：Changhoon Lee; Myung-Hwan Whangbo. Late transition metal anions acting as p-metal elements. Solid State Sciences. 2008, 10 (4): 444–449. Bibcode:2008SSSci..10..444K. doi:10.1016/j.solidstatesciences.2007.12.001. and Changhoon Lee; Myung-Hwan Whangbo; Jürgen Köhler. Analysis of Electronic Structures and Chemical Bonding of Metal-rich Compounds. 2. Presence of Dimer (T–T)^4– and Isolated T^2– Anions in the Polar Intermetallic Cr₅B₃-Type Compounds AE₅T₃ (AE = Ca, Sr; T = Au, Ag, Hg, Cd, Zn). Zeitschrift für Anorganische und Allgemeine Chemie. 2010, 636 (1): 36–40. doi:10.1002/zaac.200900421.
Ni(−2)已在Li₂[Ni(1,5-COD)₂]中觀察到，參見：Jonas, Klaus. Dilithium-Nickel-Olefin Complexes. Novel Bimetal Complexes Containing a Transition Metal and a Main Group Metal. Angew. Chem. Int. Ed. 1975, 14 (11): 752–753. doi:10.1002/anie.197507521. and Ellis, John E. Adventures with Substances Containing Metals in Negative Oxidation States. Inorganic Chemistry. 2006, 45 (8): 3167–86. PMID 16602773. doi:10.1021/ic052110i.
Cu(0)已在Cu(tris[2-(diisopropylphosphino)-phenyl]borane)中觀察到，參見：Moret, Marc-Etienne; Zhang, Limei; Peters, Jonas C. A Polar Copper–Boron One-Electron σ-Bond. J. Am. Chem. Soc. 2013, 135 (10): 3792–3795 [2023-05-28]. PMID 23418750. doi:10.1021/ja4006578. （原始内容存档于2022-10-07）.
Zn(0)已被觀察到，參見：Singh, Amit Pratap; Samuel, Prinson P.; Roesky, Herbert W.; Schwarzer, Martin C.; Frenking, Gernot; Sidhu, Navdeep S.; Dittrich, Birger. A Singlet Biradicaloid Zinc Compound and Its Nonradical Counterpart. J. Am. Chem. Soc. 2013, 135 (19): 7324–9. PMID 23600486. doi:10.1021/ja402351x. and Soleilhavoup, Michèle; Bertrand, Guy. Cyclic (Alkyl)(Amino)Carbenes (CAACs): Stable Carbenes on the Rise. Acc. Chem. Res. 2015, 48 (2): 256–266. PMID 25515548. doi:10.1021/ar5003494.
Zn(I)已在二(五甲基環戊二烯)基鋅（英语：decamethyldizincocene）（Zn₂(η⁵–C₅Me₅)₂）中觀察到，參見：Resa, I.; Carmona, E.; Gutierrez-Puebla, E.; Monge, A. Decamethyldizincocene, a Stable Compound of Zn(I) with a Zn-Zn Bond. Science. 2004, 305 (5687): 1136–8. Bibcode:2004Sci...305.1136R. PMID 15326350. S2CID 38990338. doi:10.1126/science.1101356.
據預測，Zn(III)在具有高度穩定性的基於硼烷的三元離子化合物中是穩定的，但目前在實驗中尚無已知的Zn(III)候選物質，參見：Hong Fang; Huta Banjade; Deepika; Puru Jena. Realization of the Zn3+ oxidation state. Nanoscale. 2021, 13 (33): 14041–14048. PMID 34477685. S2CID 237400349. doi:10.1039/D1NR02816B （英语）.
As(0)已被觀察到，參見：Abraham, Mariham Y.; Wang, Yuzhong; Xie, Yaoming; Wei, Pingrong; Shaefer III, Henry F.; Schleyer, P. von R.; Robinson, Gregory H. Carbene Stabilization of Diarsenic: From Hypervalency to Allotropy. Chemistry: A European Journal. 2010, 16 (2): 432–5. PMID 19937872. doi:10.1002/chem.200902840.
As(I)已在AsI中觀察到，參見：Ellis, Bobby D.; MacDonald, Charles L. B. Stabilized Arsenic(I) Iodide: A Ready Source of Arsenic Iodide Fragments and a Useful Reagent for the Generation of Clusters. Inorganic Chemistry. 2004, 43 (19): 5981–6. PMID 15360247. doi:10.1021/ic049281s.
As(IV)已在As(OH)₄及HAsO−
中觀察到，參見：Kläning, Ulrik K.; Bielski, Benon H. J.; Sehested, K. Arsenic(IV). A pulse-radiolysis study. Inorganic Chemistry. 1989, 28 (14): 2717–24. doi:10.1021/ic00313a007.
已使用DFT在[ReOSe(2-pySe)₃]中識別出Se(0)原子，參見：Cargnelutti, Roberta; Lang, Ernesto S.; Piquini, Paulo; Abram, Ulrich. Synthesis and structure of [ReOSe(2-Se-py)3]: A rhenium(V) complex with selenium(0) as a ligand. Inorganic Chemistry Communications. 2014, 45: 48–50. ISSN 1387-7003. doi:10.1016/j.inoche.2014.04.003.
Se(III)已在Se₂NBr₃中觀察到，參見：Lau, Carsten; Neumüller, Bernhard; Vyboishchikov, Sergei F.; Frenking, Gernot; Dehnicke, Kurt; Hiller, Wolfgang; Herker, Martin. Se₂NBr₃, Se₂NCl₅, Se₂NCl⁻₆: New Nitride Halides of Selenium(III) and Selenium(IV). Chemistry: A European Journal. 1996, 2 (11): 1393–1396. doi:10.1002/chem.19960021108.
Se(V)已在SeO−
3及HSeO2−
4中觀察到，參見：Kläning, Ulrik K.; Sehested, K. Selenium(V). A pulse radiolysis study. Inorganic Chemistry. 1986, 90 (21): 5460–4 [2023-05-28]. doi:10.1021/j100412a112. （原始内容存档于2019-03-22）.
Sr(I)已在SrF中觀察到，參見：P. Colarusso; Guo, B.; Zhang, K.-Q.; Bernath, P.F.; et al. High-Resolution Infrared Emission Spectrum of Strontium Monofluoride (PDF). Journal of Molecular Spectroscopy. 1996, 175 (1): 158–171. Bibcode:1996JMoSp.175..158C. doi:10.1006/jmsp.1996.0019. （原始内容 (PDF)存档于2012-03-08）.
氧化態為0的釔和所有鑭系元素（鈰及鉕除外）已在雙(1,3,5-三叔丁基苯)錯合物中觀察到，參見：Cloke, F. Geoffrey N. Zero Oxidation State Compounds of Scandium, Yttrium, and the Lanthanides. Chem. Soc. Rev. 1993, 22: 17–24. doi:10.1039/CS9932200017. and Arnold, Polly L.; Petrukhina, Marina A.; Bochenkov, Vladimir E.; Shabatina, Tatyana I.; Zagorskii, Vyacheslav V.; Cloke. Arene complexation of Sm, Eu, Tm and Yb atoms: a variable temperature spectroscopic investigation. Journal of Organometallic Chemistry. 2003-12-15, 688 (1–2): 49–55. doi:10.1016/j.jorganchem.2003.08.028.
Y(II)已在[(18-crown-6)K][(C₅H₄SiMe₃)₃Y]中觀察到，參見：MacDonald, M. R.; Ziller, J. W.; Evans, W. J. Synthesis of a Crystalline Molecular Complex of Y²⁺, [(18-crown-6)K][(C₅H₄SiMe₃)₃Y]. J. Am. Chem. Soc. 2011, 133 (40): 15914–17. PMID 21919538. doi:10.1021/ja207151y.
Zr(−1)曾被報告存在於[Zr(bipy)₃]⁻中（參見 Greenwood, N. N.; Earnshaw, A. Chemistry of the Elements 2nd. Oxford:Butterworth-Heinemann. 1997: 960. ISBN 0-7506-3365-4. 及 Holleman, Arnold F.; Wiberg, Egon; Wiberg, Nils. Zirconium. Lehrbuch der Anorganischen Chemie 101. Walter de Gruyter. 1995: 1413. ISBN 978-3-11-012641-9 （德语）. ）, 但後來被證明是Zr(+4)，參見：Bowman, A. C.; England, J.; Sprouls, S.; Weihemüller, T.; Wieghardt, K. Electronic structures of homoleptic [tris(2,2'-bipyridine)M]n complexes of the early transition metals (M = Sc, Y, Ti, Zr, Hf, V, Nb, Ta; n = 1+, 0, 1-, 2-, 3-): an experimental and density functional theoretical study. Inorganic Chemistry. 2013, 52 (4): 2242–56. PMID 23387926. doi:10.1021/ic302799s.
Zr(0)及Hf(0)出現在(η⁶-(1,3,5-^tBu)₃C₆H₃)₂M (M=Zr, Hf)及[(η⁵-C₅R₅M(CO)₄]⁻中，參見：Chirik, P. J.; Bradley, C. A. 4.06 - Complexes of Zirconium and Hafnium in Oxidation States 0 to ii. Comprehensive Organometallic Chemistry III. From Fundamentals to Applications 4. Elsevier Ltd. 2007: 697–739. ISBN 9780080450476. doi:10.1016/B0-08-045047-4/00062-5.
George, G.N.; Klein, S.I.; Nixon, J.F. Electron paramagnetic resonance spectroscopic studies on the zero-valent rhodium complex [Rh(P(OPrⁱ)₃)₄] at X-and Q-band frequencies. Chemical Physics Letters. 1984, 108 (6): 627–630. Bibcode:1984CPL...108..627G. doi:10.1016/0009-2614(84)85069-1.
Rh(VII)已知存在於RhO₃⁺陽離子中，參見：The Highest Oxidation State of Rhodium: Rhodium(VII) in [RhO3]+. Angew. Chem. Int. Ed. 2022. doi:10.1002/anie.202207688.
Pd(I)已被觀察到，參見：Crabtree, R. H. CHEMISTRY: A New Oxidation State for Pd?. Science. 2002, 295 (5553): 288–289. PMID 11786632. S2CID 94579227. doi:10.1126/science.1067921.
Pd(III)已被觀察到，參見：Powers, D. C.; Ritter, T. Palladium(III) in Synthesis and Catalysis (PDF). Topics in Organometallic Chemistry 35. 2011: 129–156. Bibcode:2011hoso.book..129P. ISBN 978-3-642-17428-5. PMC 3066514 . PMID 21461129. doi:10.1007/978-3-642-17429-2_6. （原始内容 (PDF)存档于June 12, 2013）. |journal=被忽略 (帮助)
Pd(V)已被確認存在於含有五配位數鈀原子的有機矽化合物之絡合物中，參見：Shimada, Shigeru; Li, Yong-Hua; Choe, Yoong-Kee; Tanaka, Masato; Bao, Ming; Uchimaru, Tadafumi. Multinuclear palladium compounds containing palladium centers ligated by five silicon atoms. Proceedings of the National Academy of Sciences. 2007, 104 (19): 7758–7763. doi:10.1073/pnas.0700450104.
NEW PALLADIUM OXIDATION STATE?. Chem. Eng. News. 2002, 80 (2): 8. doi:10.1021/cen-v080n002.p008. 中聲稱Pd(VI)存在, 但該實驗結果已被駁回，其中的鈀應為+2態。
Ag⁻離子已在金屬與液態氨之溶液中觀察到，參見：Tran, N. E.; Lagowski, J. J. Metal Ammonia Solutions: Solutions Containing Argentide Ions. Inorganic Chemistry. 2001, 40 (5): 1067–68. doi:10.1021/ic000333x.
Ag(0)已在低溫基質隔離（英语：Matrix isolation）條件下的羰基絡合物中觀察到，參見McIntosh, D.; Ozin, G. A. Synthesis using metal vapors. Silver carbonyls. Matrix infrared, ultraviolet-visible, and electron spin resonance spectra, structures, and bonding of silver tricarbonyl, silver dicarbonyl, silver monocarbonyl, and disilver hexacarbonyl. J. Am. Chem. Soc. 1976, 98 (11): 3167–75. doi:10.1021/ja00427a018.
In(–5)已在La₃InGe中觀察到，參見：Guloy, A. M.; Corbett, J. D. Synthesis, Structure, and Bonding of Two Lanthanum Indium Germanides with Novel Structures and Properties. Inorganic Chemistry. 1996, 35 (9): 2616–22. PMID 11666477. doi:10.1021/ic951378e.
Sn(−3)已在[Sn₂]⁶⁻中觀察到，例如在(Ba₂)⁴⁺(Mg₄)⁸⁺Sn⁴⁻(Sn₂)⁶⁻Sn²⁻中（其中有正方形層狀(Sn²⁻)_n），參見：Papoian, Garegin A.; Hoffmann, Roald. Hypervalent Bonding in One, Two, and Three Dimensions: Extending the Zintl–Klemm Concept to Nonclassical Electron-Rich Networks. Angew. Chem. Int. Ed. 2000, 2000 (39): 2408–2448 [2015-02-23]. doi:10.1002/1521-3773(20000717)39:14<2408::aid-anie2408>3.0.co;2-u. （原始内容存档于2018-10-26）.
Sb(−2)已在[Sb₂]⁴⁻及RbBa₄[Sb₂][Sb][O]中觀察到，參見：Boss, Michael; Petri, Denis; Pickhard, Frank; Zönnchen, Peter; Röhr, Caroline. Neue Barium-Antimonid-Oxide mit den Zintl-Ionen [Sb]³⁻, [Sb₂]⁴⁻ und ¹_∞[Sb_n]ⁿ⁻ / New Barium Antimonide Oxides containing Zintl Ions [Sb]³⁻, [Sb₂]⁴⁻ and ¹_∞[Sb_n]ⁿ⁻. Zeitschrift für Anorganische und Allgemeine Chemie. 2005, 631 (6–7): 1181–1190. doi:10.1002/zaac.200400546 （德语）.
Sb(0)已被觀察到，參見：Anastas Sidiropoulos. Studies of N-heterocyclic Carbene (NHC) Complexes of the Main Group Elements (PDF). : 39 [2023-05-28]. S2CID 132399530. doi:10.4225/03/5B0F4BDF98F60. （原始内容存档 (PDF)于2020-02-18）.
Sb(I)及Sb(II)已在有機銻化合物中觀察到；關於Sb(I)，參見：Šimon, Petr; de Proft, Frank; Jambor, Roman; Růžička, Aleš; Dostál, Libor. Monomeric Organoantimony(I) and Organobismuth(I) Compounds Stabilized by an NCN Chelating Ligand: Syntheses and Structures. Angewandte Chemie International Edition. 2010, 49 (32): 5468–5471. PMID 20602393. doi:10.1002/anie.201002209.
Sb(IV)已在[SbCl
6]²⁻中觀察到，參見：Nobuyoshi Shinohara; Masaaki Ohsima. Production of Sb(IV) Chloro Complex by Flash Photolysis of the Corresponding Sb(III) and Sb(V) Complexes in CH3CN and CHCl3. Bulletin of the Chemical Society of Japan. 2000, 73 (7): 1599–1604. doi:10.1246/bcsj.73.1599.
Te(III)已在[Te(N(SiMe₃)₂)₂]⁺中觀察到，參見：Heinze, Thorsten; Roesky, Herbert W.; Pauer, Frank; Stalke, Dietmar; Sheldrick, George M. Synthesis and Structure of the First Tellurium(III) Radical Cation. Angewandte Chemie International Edition. 1991, 30 (12): 1678 [2015-02-23]. doi:10.1002/anie.199116771. （原始内容存档于2018-09-19）.
Te(V)曾被Greenwood and Earnshaw提及，但他們沒有舉出任何Te(V)化合物的例子。而長久以來被認為是十氟化二碲（英语：Ditellurium decafluoride）（Te₂F₁₀）的物質實際上是雙(五氟碲基)氧化物：F₅TeOTeF₅，參見：Watkins, P. M. Ditellurium decafluoride - A Continuing Myth. Journal of Chemical Education. 1974, 51 (9): 520–521. Bibcode:1974JChEd..51..520W. doi:10.1021/ed051p520. 不過，Te(V)已在HTeO−
、TeO−
、HTeO−
2及TeO−
3中觀察到，參見：Kläning, Ulrik K.; Sehested, K. Tellurium(V). A Pulse Radiolysis Study. The Journal of Physical Chemistry A. 2001, 105 (27): 6637–45 [2023-05-28]. Bibcode:2001JPCA..105.6637K. doi:10.1021/jp010577i. （原始内容存档于2019-03-22）.
I(II)已知存在於一氧化物（IO）中，參見：Nikitin, I V. Halogen monoxides. Russian Chemical Reviews. 31 August 2008, 77 (8): 739–749. Bibcode:2008RuCRv..77..739N. doi:10.1070/RC2008v077n08ABEH003788.
I(VI)已在IO₃、IO₄²⁻、H₅IO₆⁻、H₂IO₅²⁻、H₄IO₆²⁻及HIO₅³⁻中觀察到，參見：Kläning, Ulrik K.; Sehested, Knud; Wolff, Thomas. Laser flash photolysis and pulse radiolysis of iodate and periodate in aqueous solution. Properties of iodine(VI). J. Chem. Soc., Faraday Trans. 1. 1981, 77 (7): 1707–18. doi:10.1039/F19817701707.
Ba(I)已在一氟化鋇（BaF）中觀察到，參見：P. Colarusso; Guo, B.; Zhang, K.-Q.; Bernath, P.F.; et al. High-Resolution Fourier Transform Infrared Emission Spectrum of Barium Monofluoride (PDF). Journal of Molecular Spectroscopy. 1995, 170 (1): 59. Bibcode:1996JMoSp.175..158C. doi:10.1006/jmsp.1996.0019. （原始内容 (PDF)存档于2005-03-10）.
La(I)、Pr(I)、Tb(I)、Tm(I)及Yb(I)已在MB₈⁻簇合物中觀察到，參見：Li, Wan-Lu; Chen, Teng-Teng; Chen, Wei-Jia; Li, Jun; Wang, Lai-Sheng. Monovalent lanthanide(I) in borozene complexes. Nature Communications. 2021, 12: 6467 [2023-05-28]. doi:10.1038/s41467-021-26785-9. （原始内容存档于2022-09-26）.
Pr(I)已在[PrB₄]⁻中觀察到，參見：Chen, Xin; Chen, Teng-Teng; Li, Wang-Lu; Lu, Jun-Bo; Zhao, Li-Juan; Jian, Tian; Hu, Han-Shi; Wang, Lai-Sheng; Li, Jun. Lanthanides with Unusually Low Oxidation States in the PrB₃^– and PrB₄^– Boride Clusters. Inorganic Chemistry. 2018-12-13, 58 (1): 411–418. PMID 30543295. S2CID 56148031. doi:10.1021/acs.inorgchem.8b02572.
Pr(V)已在[PrO₂]⁺中觀察到，參見：Zhang, Qingnan; Hu, Shu-Xian; Qu, Hui; Su, Jing; Wang, Guanjun; Lu, Jun-Bo; Chen, Mohua; Zhou, Mingfei; Li, Jun. Pentavalent Lanthanide Compounds: Formation and Characterization of Praseodymium(V) Oxides. Angewandte Chemie International Edition. 2016-06-06, 55 (24): 6896–6900. ISSN 1521-3773. PMID 27100273. doi:10.1002/anie.201602196.
Hu, Shu-Xian; Jian, Jiwen; Su, Jing; Wu, Xuan; Li, Jun; Zhou, Mingfei. Pentavalent lanthanide nitride-oxides: NPrO and NPrO− complexes with N≡Pr triple bonds. Chemical Science. 2017, 8 (5): 4035–4043. ISSN 2041-6520. PMC 5434915 . PMID 28580119. doi:10.1039/C7SC00710H （英语）.
所有鑭系元素（鑭至鎦）的+2氧化態均已在其二鹵化物和鹼土金屬二鹵化物形成的稀固溶體中（參閱：Holleman, Arnold Frederik; Wiberg, Egon, Wiberg, Nils , 编, Inorganic Chemistry, 由Eagleson, Mary; Brewer, William翻译, San Diego/Berlin: Academic Press/De Gruyter, 2001, ISBN 0-12-352651-5 ，鑭、釓、鎦除外）以及其有機金屬分子錯合物中（鉕除外）觀察到，參見：Lanthanides Topple Assumptions （页面存档备份，存于互联网档案馆） and Meyer, G. All the Lanthanides Do It and Even Uranium Does Oxidation State +2. Angewandte Chemie International Edition. 2014, 53 (14): 3550–51. PMID 24616202. doi:10.1002/anie.201311325. 。此外，雖然所有鑭系元素皆形成二氫化物（LnH₂）、二碳化物（LnC₂）、一硫化物（LnS）、一硒化物（LnSe）和一碲化物（LnTe），但對於大多數鑭系元素，這些化合物中的鑭系離子實為+3態，伴隨著離域至導帶的電子，例如：Ln³⁺(H⁻)₂(e⁻)。
Os(−1)已在Na[Os(CO)
13]中觀察到，參見：Krause, J.; Siriwardane, Upali; Salupo, Terese A.; Wermer, Joseph R.; Knoeppel, David W.; Shore, Sheldon G. Preparation of [Os₃(CO)₁₁]²⁻ and its reactions with Os₃(CO)₁₂; structures of [Et₄N] [HOs₃(CO)₁₁] and H₂OsS₄(CO). Journal of Organometallic Chemistry. 1993, 454 (1–2): 263–271. doi:10.1016/0022-328X(93)83250-Y. and Carter, Willie J.; Kelland, John W.; Okrasinski, Stanley J.; Warner, Keith E.; Norton, Jack R. Mononuclear hydrido alkyl carbonyl complexes of osmium and their polynuclear derivatives. Inorganic Chemistry. 1982, 21 (11): 3955–3960. doi:10.1021/ic00141a019.
Ir(VIII)已在四氧化銥（IrO₄）中觀察到，參見：Gong, Yu; Zhou, Mingfei; Kaupp, Martin; Riedel, Sebastian. Formation and Characterization of the Iridium Tetroxide Molecule with Iridium in the Oxidation State +VIII. Angewandte Chemie International Edition. 2009, 48 (42): 7879–7883. PMID 19593837. doi:10.1002/anie.200902733.
Ir(IX)已在IrO+
4中觀察到，參見：Wang, Guanjun; Zhou, Mingfei; Goettel, James T.; Schrobilgen, Gary G.; Su, Jing; Li, Jun; Schlöder, Tobias; Riedel, Sebastian. Identification of an iridium-containing compound with a formal oxidation state of IX. Nature. 21 August 2014, 514 (7523): 475–477. Bibcode:2014Natur.514..475W. PMID 25341786. S2CID 4463905. doi:10.1038/nature13795.
Pt(−1)及Pt(−2)已分別在鋇的鉑化物BaPt及Ba₂Pt中觀察到，參見：Karpov, Andrey; Konuma, Mitsuharu; Jansen, Martin. An experimental proof for negative oxidation states of platinum: ESCA-measurements on barium platinides. Chemical Communications. 2006, (8): 838–840. PMID 16479284. doi:10.1039/b514631c.
Pt(I)及Pt(III)已在雙金屬及多金屬物質中中觀察到，參見：Kauffman, George B.; Thurner, Joseph J.; Zatko, David A. Ammonium Hexachloroplatinate(IV). Inorganic Syntheses 9. 1967: 182–185. ISBN 978-0-470-13240-1. doi:10.1002/9780470132401.ch51.
Au(0)已被觀察到，參見：Mézaille, Nicolas; Avarvari, Narcis; Maigrot, Nicole; Ricard, Louis; Mathey, François; Le Floch, Pascal; Cataldo, Laurent; Berclaz, Théo; Geoffroy, Michel. Gold(I) and Gold(0) Complexes of Phosphinine‐Based Macrocycles. Angewandte Chemie International Edition. 1999, 38 (21): 3194–3197. PMID 10556900. doi:10.1002/(SICI)1521-3773(19991102)38:21<3194::AID-ANIE3194>3.0.CO;2-O.
Hg(IV)曾被報告發現存在於四氟化汞（HgF₄）中，參見：Xuefang Wang; Lester Andrews; Sebastian Riedel; Martin Kaupp. Mercury Is a Transition Metal: The First Experimental Evidence for HgF₄. Angew. Chem. Int. Ed. 2007, 46 (44): 8371–8375. PMID 17899620. doi:10.1002/anie.200703710. 但之後的實驗無法證實該發現，參閱：Is mercury a transition metal? 互联网档案馆的存檔，存档日期2016-10-12.
Tl(−5)已在Na₂₃K₉Tl_15.3中觀察到，參見：Dong, Z.-C.; Corbett, J. D. Na₂₃K₉Tl_15.3: An Unusual Zintl Compound Containing Apparent Tl₅⁷⁻, Tl₄⁸⁻, Tl₃⁷⁻, and Tl⁵⁻ Anions. Inorganic Chemistry. 1996, 35 (11): 3107–12. PMID 11666505. doi:10.1021/ic960014z.
Tl(+2)已在四(超甲矽烷基)二鉈（[(Me₃Si)Si]₂Tl—Tl[Si(SiMe₃)]₂）中觀察到，參見：Sonja Henkel; Dr. Karl Wilhelm Klinkhammer; Dr. Wolfgang Schwarz. Tetrakis(hypersilyl)dithallium(Tl—Tl): A Divalent Thallium Compound. Angew. Chem. Int. Ed. 1994, 33 (6): 681–683. doi:10.1002/anie.199406811.
Pb(−2)已在BaPb中觀察到，參見：Ferro, Riccardo. Nicholas C. Norman , 编. Intermetallic Chemistry. Elsevier. 2008: 505. ISBN 978-0-08-044099-6. and Todorov, Iliya; Sevov, Slavi C. Heavy-Metal Aromatic Rings: Cyclopentadienyl Anion Analogues Sn₅⁶⁻ and Pb₅⁶⁻ in the Zintl Phases Na₈BaPb₆, Na₈BaSn₆, and Na₈EuSn₆. Inorganic Chemistry. 2004, 43 (20): 6490–94. doi:10.1021/ic000333x.
含Pb(0)的羰基錯合物已在鉛原子和一氧化碳間的反應中觀察到，參見：Ling, Jiang; Qiang, Xu. Observation of the lead carbonyls Pb_nCO (n=1–4): Reactions of lead atoms and small clusters with carbon monoxide in solid argon. The Journal of Chemical Physics. 122 (3): 034505. 2005, 122 (3): 34505 [2023-05-28]. Bibcode:2005JChPh.122c4505J. ISSN 0021-9606. PMID 15740207. doi:10.1063/1.1834915. （原始内容存档于2022-11-08）.
Pb(+1)及Pb(+3)已在有機鉛化合物中觀察到，如六甲基二鉛烷（Pb₂(CH₃)₆）等；有關Pb(I)的資訊，參閱：Siew-Peng Chia; Hong-Wei Xi; Yongxin Li; Kok Hwa Lim; Cheuk-Wai So. A Base-Stabilized Lead(I) Dimer and an Aromatic Plumbylidenide Anion. Angew. Chem. Int. Ed. 2013, 52 (24): 6298–6301. PMID 23629949. doi:10.1002/anie.201301954.
Bi(0)已知存在於二鉍烯的N-雜環碳烯錯合物中，參見：Deka, Rajesh; Orthaber, Andreas. Carbene chemistry of arsenic, antimony, and bismuth: origin, evolution and future prospects. Royal Society of Chemistry. May 6, 2022, (51): 8540 [2023-05-28]. doi:10.1039/d2dt00755j. （原始内容存档于2022-09-22）.
Bi(+2)已在dibismuthine（R₂Bi—BiR₂）中觀察到，參見：Arthur J. Ashe III. Thermochromic Distibines and Dibismuthines 30. 1990: 77–97. ISBN 9780120311309. doi:10.1016/S0065-3055(08)60499-2. |journal=被忽略 (帮助)
Bi(IV)已被觀察到，參見：A. I. Aleksandrov, I. E. Makarov. Formation of Bi(II) and Bi(IV) in aqueous hydrochloric solutions of Bi(III). Bulletin of the Academy of Sciences of the USSR, Division of Chemical Science. 1987, 36 (2): 217–220. S2CID 94865394. doi:10.1007/BF00959349.
Po(V)已在dioxidopolonium(1+)（PoO+
）中觀察到，參見：Thayer, John S. Relativistic Effects and the Chemistry of the Heavier Main Group Elements. Relativistic Methods for Chemists. Challenges and Advances in Computational Chemistry and Physics 10. 2010: 78. ISBN 978-1-4020-9974-8. doi:10.1007/978-1-4020-9975-5_2.
Rn(II)已在二氟化氡（RnF₂）中觀察到，參見：Stein, L. Ionic Radon Solution. Science. 1970, 168 (3929): 362–4. Bibcode:1970Sci...168..362S. PMID 17809133. S2CID 31959268. doi:10.1126/science.168.3929.362. and Kenneth S. Pitzer. Fluorides of radon and element 118. J. Chem. Soc., Chem. Commun. 1975, (18): 760b – 761 [2023-05-28]. doi:10.1039/C3975000760b. （原始内容存档于2021-12-08）.
Th(-I)及U(-I)已在氣相中以八羰基陰離子的形式被檢測到，參見：Chaoxian, Chi; Sudip, Pan; Jiaye, Jin; Luyan, Meng; Mingbiao, Luo; Lili, Zhao; Mingfei, Zhou; Gernot, Frenking. Octacarbonyl Ion Complexes of Actinides [An(CO)₈]^+/− (An=Th, U) and the Role of f Orbitals in Metal–Ligand Bonding. Chemistry (Weinheim an der Bergstrasse, Germany). 25 (50): 11772–11784. 2019, 25 (50): 11772–11784. ISSN 0947-6539. PMC 6772027 . PMID 31276242. doi:10.1002/chem.201902625.
Th(I)已知存在於溴化釷(I)（ThBr）中，參見：Wickleder, Mathias S.; Fourest, Blandine; Dorhout, Peter K. Thorium. Morss, Lester R.; Edelstein, Norman M.; Fuger, Jean (编). The Chemistry of the Actinide and Transactinide Elements (PDF) 3 3rd. Dordrecht, the Netherlands: Springer. 2006: 52–160. ISBN 978-1-4020-3555-5. doi:10.1007/1-4020-3598-5_3. （原始内容 (PDF)存档于2016-03-07）.
Th(II)及Th(III)已在[Th^II{η⁵-C₅H₃(SiMe₃)₂}₃]⁻及[Th^III{η⁵-C₅H₃(SiMe₃)₂}₃]中觀察到，參見：Langeslay, Ryan R.; Fieser, Megan E.; Ziller, Joseph W.; Furche, Philip; Evans, William J. Synthesis, structure, and reactivity of crystalline molecular complexes of the {[C₅H₃(SiMe₃)₂]₃Th}¹⁻ anion containing thorium in the formal +2 oxidation state. Chem. Sci. 2015, 6 (1): 517–521. PMC 5811171 . PMID 29560172. doi:10.1039/C4SC03033H.
Th(-I)及U(-I)已在氣相中以八羰基陰離子的形式被檢測到，參見：Chaoxian, Chi; Sudip, Pan; Jiaye, Jin; Luyan, Meng; Mingbiao, Luo; Lili, Zhao; Mingfei, Zhou; Gernot, Frenking. Octacarbonyl Ion Complexes of Actinides [An(CO)₈]^+/− (An=Th, U) and the Role of f Orbitals in Metal–Ligand Bonding. Chemistry (Weinheim an der Bergstrasse, Germany). 25 (50): 11772–11784. 2019, 25 (50): 11772–11784. ISSN 0947-6539. PMC 6772027 . PMID 31276242. doi:10.1002/chem.201902625.
U(II)已在[K(2.2.2-Cryptand)][(C₅H₄SiMe₃)₃U]中觀察到，參見：MacDonald, Matthew R.; Fieser, Megan E.; Bates, Jefferson E.; Ziller, Joseph W.; Furche, Filipp; Evans, William J. Identification of the +2 Oxidation State for Uranium in a Crystalline Molecular Complex, [K(2.2.2-Cryptand)][(C₅H₄SiMe₃)₃U]. J. Am. Chem. Soc. 2013, 135 (36): 13310–13313. PMID 23984753. doi:10.1021/ja406791t.
Np(II)、Np(III)及Np(IV)已被觀察到，參見：Dutkiewicz, Michał S.; Apostolidis, Christos; Walter, Olaf; Arnold, Polly L. Reduction chemistry of neptunium cyclopentadienide complexes: from structure to understanding. Chem. Sci. 2017, 8 (4): 2553–2561. PMC 5431675 . PMID 28553487. doi:10.1039/C7SC00034K.
Pu(II)已在{Pu[C₅H₃(SiMe₃)₂]₃}−中觀察到，參見：Windorff, Cory J.; Chen, Guo P; Cross, Justin N; Evans, William J.; Furche, Filipp; Gaunt, Andrew J.; Janicke, Michael T.; Kozimor, Stosh A.; Scott, Brian L. Identification of the Formal +2 Oxidation State of Plutonium: Synthesis and Characterization ofref name="curium5" {Pu^II[C₅H₃(SiMe₃)₂]₃}−. J. Am. Chem. Soc. 2017, 139 (11): 3970–3973. PMID 28235179. doi:10.1021/jacs.7b00706.
Pu(VIII)已在PuO
4中觀察到，參見：Nikonov, M. V.; Kiselev, Yu. M.; Tananaev, I. G.; Myasoedov, B. F. Plutonium volatility in ozonization of alkaline solutions of Pu(VI) hydroxo complexes. Doklady Chemistry. March 2011, 437 (1): 69–71. S2CID 95951175. doi:10.1134/S0012500811030104. ，以及 Kiselev, Yu. M.; Nikonov, M. V.; Dolzhenko, V. D.; Ermilov, A. Yu.; Tananaev, I. G.; Myasoedov, B. F. On existence and properties of plutonium(VIII) derivatives. Radiochimica Acta. 17 January 2014, 102 (3): 227–237. S2CID 100915090. doi:10.1515/ract-2014-2146.
Cm(V)、Bk(V)及Cf(V)已在BkO₂⁺、CfO₂⁺、CmO₂(NO₃)₂⁻、BkO₂(NO₃)₂⁻及CfO₂(NO₃)₂⁻中觀察到，參見：Dau, Phuong Diem; Vasiliu, Monica; Peterson, Kirk A; Dixon, David A; Gibsoon, John K. Remarkably High Stability of Late Actinide Dioxide Cations: Extending Chemistry to Pentavalent Berkelium and Californium. Chemistry - A European Journal. October 2017, 23 (68): 17369–17378 [2023-05-28]. PMID 29024093. doi:10.1002/chem.201704193. （原始内容存档于2023-03-26）.
Kovács, Attila; Dau, Phuong D.; Marçalo, Joaquim; Gibson, John K. Pentavalent Curium, Berkelium, and Californium in Nitrate Complexes: Extending Actinide Chemistry and Oxidation States. Inorg. Chem. (American Chemical Society). 2018, 57 (15): 9453–9467. OSTI 1631597. PMID 30040397. S2CID 51717837. doi:10.1021/acs.inorgchem.8b01450.
Cm(VI)已在三氧化鋦（CmO₃）及二氧化鋦(2+)離子（CmO+
2）中觀察到，參見：Domanov, V. P.; Lobanov, Yu. V. Formation of volatile curium(VI) trioxide CmO₃. Radiochemistry. October 2011, 53 (5): 453–6. S2CID 98052484. doi:10.1134/S1066362211050018.
Cm(VIII)曾被報告可能存在於四氧化鋦（CmO₄）中，參閱：Domanov, V. P. Possibility of generation of octavalent curium in the gas phase in the form of volatile tetraoxide CmO₄. Radiochemistry. January 2013, 55 (1): 46–51. S2CID 98076989. doi:10.1134/S1066362213010098. 然而，後續的實驗顯示該物質似乎不存在：Zaitsevskii, Andréi; Schwarz, W H Eugen. Structures and stability of AnO4 isomers, An = Pu, Am, and Cm: a relativistic density functional study. Physical Chemistry Chemical Physics. April 2014, 2014 (16): 8997–9001. Bibcode:2014PCCP...16.8997Z. PMID 24695756. doi:10.1039/c4cp00235k.
Peterson, J. R.; Hobart, D. E. The Chemistry of Berkelium. Emeléus, Harry Julius (编). Advances in inorganic chemistry and radiochemistry 28. Academic Press. 1984: 29–64. ISBN 978-0-12-023628-2. doi:10.1016/S0898-8838(08)60204-4.
Sullivan, Jim C.; Schmidt, K. H.; Morss, L. R.; Pippin, C. G.; Williams, C. Pulse radiolysis studies of berkelium(III): preparation and identification of berkelium(II) in aqueous perchlorate media. Inorganic Chemistry. 1988, 27 (4): 597. doi:10.1021/ic00277a005.
Es(IV)已知存在於氟化鑀(IV)（EsF₄）中，參見：Kleinschmidt, P. Thermochemistry of the actinides. Journal of Alloys and Compounds. 1994,. 213–214: 169–172 [2023-05-28]. doi:10.1016/0925-8388(94)90898-2. （原始内容存档于2020-03-16）.
Sg(VI)已在氫氧化氧𨭎（SgO₂(OH)₂）中觀察到，參見：Huebener, S.; Taut, S.; Vahle, A.; Dressler, R.; Eichler, B.; Gäggeler, H. W.; Jost, D.T.; Piguet, D.; et al. Physico-chemical characterization of seaborgium as oxide hydroxide (PDF). Radiochim. Acta. 2001, 89 (11–12_2001): 737–741. S2CID 98583998. doi:10.1524/ract.2001.89.11-12.737. （原始内容 (PDF)存档于2014-10-25）.
Sg(0)已在六羰基𨭎（Sg(CO)₆）中觀察到，參見：Even, J.; Yakushev, A.; Dullmann, C. E.; Haba, H.; Asai, M.; Sato, T. K.; Brand, H.; Di Nitto, A.; Eichler, R.; Fan, F. L.; Hartmann, W.; Huang, M.; Jager, E.; Kaji, D.; Kanaya, J.; Kaneya, Y.; Khuyagbaatar, J.; Kindler, B.; Kratz, J. V.; Krier, J.; Kudou, Y.; Kurz, N.; Lommel, B.; Miyashita, S.; Morimoto, K.; Morita, K.; Murakami, M.; Nagame, Y.; Nitsche, H.; et al. Synthesis and detection of a seaborgium carbonyl complex. Science. 2014, 345 (6203): 1491–3. Bibcode:2014Sci...345.1491E. PMID 25237098. S2CID 206558746. doi:10.1126/science.1255720.
Langmuir, Irving. THE ARRANGEMENT OF ELECTRONS IN ATOMS AND MOLECULES.. Journal of the American Chemical Society. 1919-06, 41 (6): 868–934 [2022-03-25]. ISSN 0002-7863. doi:10.1021/ja02227a002. （原始内容存档于2020-05-09）（英语）.

dtu.dk

orbit.dtu.dk

Se(V)已在SeO−
3及HSeO2−
4中觀察到，參見：Kläning, Ulrik K.; Sehested, K. Selenium(V). A pulse radiolysis study. Inorganic Chemistry. 1986, 90 (21): 5460–4 [2023-05-28]. doi:10.1021/j100412a112. （原始内容存档于2019-03-22）.
Te(V)曾被Greenwood and Earnshaw提及，但他們沒有舉出任何Te(V)化合物的例子。而長久以來被認為是十氟化二碲（英语：Ditellurium decafluoride）（Te₂F₁₀）的物質實際上是雙(五氟碲基)氧化物：F₅TeOTeF₅，參見：Watkins, P. M. Ditellurium decafluoride - A Continuing Myth. Journal of Chemical Education. 1974, 51 (9): 520–521. Bibcode:1974JChEd..51..520W. doi:10.1021/ed051p520. 不過，Te(V)已在HTeO−
、TeO−
、HTeO−
2及TeO−
3中觀察到，參見：Kläning, Ulrik K.; Sehested, K. Tellurium(V). A Pulse Radiolysis Study. The Journal of Physical Chemistry A. 2001, 105 (27): 6637–45 [2023-05-28]. Bibcode:2001JPCA..105.6637K. doi:10.1021/jp010577i. （原始内容存档于2019-03-22）.

escholarship.org

Rn(II)已在二氟化氡（RnF₂）中觀察到，參見：Stein, L. Ionic Radon Solution. Science. 1970, 168 (3929): 362–4. Bibcode:1970Sci...168..362S. PMID 17809133. S2CID 31959268. doi:10.1126/science.168.3929.362. and Kenneth S. Pitzer. Fluorides of radon and element 118. J. Chem. Soc., Chem. Commun. 1975, (18): 760b – 761 [2023-05-28]. doi:10.1039/C3975000760b. （原始内容存档于2021-12-08）.
Cm(V)、Bk(V)及Cf(V)已在BkO₂⁺、CfO₂⁺、CmO₂(NO₃)₂⁻、BkO₂(NO₃)₂⁻及CfO₂(NO₃)₂⁻中觀察到，參見：Dau, Phuong Diem; Vasiliu, Monica; Peterson, Kirk A; Dixon, David A; Gibsoon, John K. Remarkably High Stability of Late Actinide Dioxide Cations: Extending Chemistry to Pentavalent Berkelium and Californium. Chemistry - A European Journal. October 2017, 23 (68): 17369–17378 [2023-05-28]. PMID 29024093. doi:10.1002/chem.201704193. （原始内容存档于2023-03-26）.

europepmc.org

Bi(0)已知存在於二鉍烯的N-雜環碳烯錯合物中，參見：Deka, Rajesh; Orthaber, Andreas. Carbene chemistry of arsenic, antimony, and bismuth: origin, evolution and future prospects. Royal Society of Chemistry. May 6, 2022, (51): 8540 [2023-05-28]. doi:10.1039/d2dt00755j. （原始内容存档于2022-09-22）.

gsi.de

Bh(VII)已在氯氧化𨨏（BhO₃Cl）中觀察到，參見："Gas chemical investigation of bohrium (Bh, element 107)" 互联网档案馆的存檔，存档日期2008-02-28., Eichler et al., GSI Annual Report 2000. Retrieved on 2008-02-29
Hs(VIII)已在四氧化𨭆（HsO₄）中觀察到，參見：Chemistry of Hassium (PDF). Gesellschaft für Schwerionenforschung mbH. 2002 [2007-01-31]. （原始内容存档 (PDF)于2012-03-11）.

www-w2k.gsi.de

Sg(VI)已在氫氧化氧𨭎（SgO₂(OH)₂）中觀察到，參見：Huebener, S.; Taut, S.; Vahle, A.; Dressler, R.; Eichler, B.; Gäggeler, H. W.; Jost, D.T.; Piguet, D.; et al. Physico-chemical characterization of seaborgium as oxide hydroxide (PDF). Radiochim. Acta. 2001, 89 (11–12_2001): 737–741. S2CID 98583998. doi:10.1524/ract.2001.89.11-12.737. （原始内容 (PDF)存档于2014-10-25）.

harvard.edu

ui.adsabs.harvard.edu

已合成出在高壓下熱力學穩定的氦化鈉（(Na⁺)₂He(e^-)₂），參見：Dong, Xiao; Oganov, Artem R.; Goncharov, Alexander F.; Stavrou, Elissaios; Lobanov, Sergey; Saleh, Gabriele; Qian, Guang-Rui; Zhu, Qiang; Gatti, Carlo; Deringer, Volker L.; Dronskowski, Richard; Zhou, Xiang-Feng; Prakapenka, Vitali B.; Konôpková, Zuzana; Popov, Ivan A.; Boldyrev, Alexander I.; Wang, Hui-Tian. A stable compound of helium and sodium at high pressure. Nature Chemistry. 6 February 2017, 9 (5): 440–445. Bibcode:2017NatCh...9..440D. PMID 28430195. S2CID 20459726. arXiv:1309.3827 . doi:10.1038/nchem.2716.
Be(I)已在一氫化鈹（英语：Beryllium monohydride）（BeH）中觀察到，參見：Shayesteh, A.; Tereszchuk, K.; Bernath, P. F.; Colin, R. Infrared Emission Spectra of BeH and BeD (PDF). J. Chem. Phys. 2003, 118 (3): 1158 [2007-12-10]. Bibcode:2003JChPh.118.1158S. doi:10.1063/1.1528606. （原始内容 (PDF)存档于2007-12-02）. and in [(CAAC)₂Be]^+• [CAAC = cyclic (alkyl)(amino)carbene], see Wang, Guocang; Walley, Jacob E.; Dickie, Diane E.; Pan, Sudip; Frenking, Gernot; Gilliard Jr., Robert G. A Stable, Crystalline Beryllium Radical Cation. J. Am. Chem. Soc. 2020, 142 (10): 4560–4 [2020-11-17]. PMID 32088963. S2CID 211262005. doi:10.1021/jacs.9b13777. （原始内容存档于2022-09-24）.
B(0)已在雙硼炔（英语：diboryne）中觀察到，參見：Braunschweig, H.; Dewhurst, R. D.; Hammond, K.; Mies, J.; Radacki, K.; Vargas, A. Ambient-Temperature Isolation of a Compound with a Boron-Boron Triple Bond. Science. 2012, 336 (6087): 1420–2. Bibcode:2012Sci...336.1420B. PMID 22700924. S2CID 206540959. doi:10.1126/science.1221138.
實驗表明，氯化鈉在高壓下存在幾種不尋常的化學計量，例如Na₃Cl，其中包含一層Na(0)原子，參見：Zhang, W.; Oganov, A. R.; Goncharov, A. F.; Zhu, Q.; Boulfelfel, S. E.; Lyakhov, A. O.; Stavrou, E.; Somayazulu, M.; Prakapenka, V. B.; Konôpková, Z. Unexpected Stable Stoichiometries of Sodium Chlorides. Science. 2013, 342 (6165): 1502–1505. Bibcode:2013Sci...342.1502Z. PMID 24357316. S2CID 15298372. arXiv:1310.7674 . doi:10.1126/science.1244989.
Mg(0)已在Na₂Mg₂²⁺團簇與龐大有機配體配位形成的絡合物中觀察到，參見：Rösch, B.; Gentner, T. X.; Eyselein, J.; Langer, J.; Elsen, H.; Li, W.; Harder, S. Strongly reducing magnesium(0) complexes. Nature. 2021, 592 (7856): 717–721. Bibcode:2021Natur.592..717R. PMID 33911274. S2CID 233447380. doi:10.1038/s41586-021-03401-w
含有Mg(I)的低價鎂化合物已使用大陰離子配體製得，參見：Green, S. P.; Jones C.; Stasch A. Stable Magnesium(I) Compounds with Mg-Mg Bonds. Science. December 2007, 318 (5857): 1754–1757. Bibcode:2007Sci...318.1754G. PMID 17991827. S2CID 40657565. doi:10.1126/science.1150856.
Al(II)已在一氧化鋁（AlO）中觀察到，參見：Tyte, D.C. Red (B2Π–A2σ) Band System of Aluminium Monoxide. Nature. 1964, 202 (4930): 383–384. Bibcode:1964Natur.202..383T. S2CID 4163250. doi:10.1038/202383a0 , and in dialanes (R₂Al—AlR₂); see Uhl, Werner. Organoelement Compounds Possessing Al—Al, Ga—Ga, In—In, and Tl—Tl Single Bonds. Advances in Organometallic Chemistry. 2004, 51: 53–108. doi:10.1016/S0065-3055(03)51002-4.
已在以氖作為基質的隔離（英语：Matrix isolation）下觀察到鈣、鍶、鋇的八羰基配合物，但尚不清楚這些是否為其0價態配合物，因為計算結果否定了配合物中金屬原子和配體形成共價鍵或離子鍵與否，參見：Wu, X.; Zhao, L.; Jin, J.; Pan, S.; Li, W.; Jin, X.; Wang, G.; Zhou, M.; Frenking, G. Observation of alkaline earth complexes M(CO)8 (M = Ca, Sr, or Ba) that mimic transition metals. Science. 2018, 361 (6405): 912–916. Bibcode:2018Sci...361..912W. PMID 30166489. S2CID 52131470. doi:10.1126/science.aau0839
Fe(VII)已在[FeO₄]⁻中觀察到，參見：Lu, Jun-Bo; Jian, Jiwen; Huang, Wei; Lin, Hailu; Zhou, Mingfei. Experimental and theoretical identification of the Fe(VII) oxidation state in FeO₄⁻. Physical Chemistry Chemical Physics. 2016, 18 (45): 31125–31131. Bibcode:2016PCCP...1831125L. PMID 27812577. doi:10.1039/C6CP06753K.
Fe(−4)、Ru(−4)和Os(−4)已在含有八面體配合物[MIn_6−xSn_x]的富金屬化合物中觀察到；Pt(−3)（以二聚體陰離子[Pt–Pt]⁶⁻的形式）、Cu(−2)、Zn(−2)、Ag(−2)、Cd(−2)、Au(−2)和Hg(−2)（以二聚體和單體陰離子之形式；Zn、Cd、Hg的二聚體離子最初被報告為[T–T]²⁻的形式、但後來的研究顯示所有這些元素的二聚體陰離子皆為[T–T]⁴⁻形式）已在下列化合物中觀察到：La₂Pt₂In、La₂Cu₂In、Ca₅Au₃、Ca₅Ag₃、Ca₅Hg₃、Sr₅Cd₃、Ca₅Zn₃（結構為(AE²⁺)₅(T–T)⁴⁻T^{2 −}⋅4e⁻）、Yb₃Ag₂、Ca₅Au₄和Ca₃Hg₂；Au(-3)已在ScAuSn及其他18電子的半赫斯勒化合物（英语：Heusler compound）中觀察到。參見：Changhoon Lee; Myung-Hwan Whangbo. Late transition metal anions acting as p-metal elements. Solid State Sciences. 2008, 10 (4): 444–449. Bibcode:2008SSSci..10..444K. doi:10.1016/j.solidstatesciences.2007.12.001. and Changhoon Lee; Myung-Hwan Whangbo; Jürgen Köhler. Analysis of Electronic Structures and Chemical Bonding of Metal-rich Compounds. 2. Presence of Dimer (T–T)^4– and Isolated T^2– Anions in the Polar Intermetallic Cr₅B₃-Type Compounds AE₅T₃ (AE = Ca, Sr; T = Au, Ag, Hg, Cd, Zn). Zeitschrift für Anorganische und Allgemeine Chemie. 2010, 636 (1): 36–40. doi:10.1002/zaac.200900421.
Zn(I)已在二(五甲基環戊二烯)基鋅（英语：decamethyldizincocene）（Zn₂(η⁵–C₅Me₅)₂）中觀察到，參見：Resa, I.; Carmona, E.; Gutierrez-Puebla, E.; Monge, A. Decamethyldizincocene, a Stable Compound of Zn(I) with a Zn-Zn Bond. Science. 2004, 305 (5687): 1136–8. Bibcode:2004Sci...305.1136R. PMID 15326350. S2CID 38990338. doi:10.1126/science.1101356.
Sr(I)已在SrF中觀察到，參見：P. Colarusso; Guo, B.; Zhang, K.-Q.; Bernath, P.F.; et al. High-Resolution Infrared Emission Spectrum of Strontium Monofluoride (PDF). Journal of Molecular Spectroscopy. 1996, 175 (1): 158–171. Bibcode:1996JMoSp.175..158C. doi:10.1006/jmsp.1996.0019. （原始内容 (PDF)存档于2012-03-08）.
George, G.N.; Klein, S.I.; Nixon, J.F. Electron paramagnetic resonance spectroscopic studies on the zero-valent rhodium complex [Rh(P(OPrⁱ)₃)₄] at X-and Q-band frequencies. Chemical Physics Letters. 1984, 108 (6): 627–630. Bibcode:1984CPL...108..627G. doi:10.1016/0009-2614(84)85069-1.
Pd(III)已被觀察到，參見：Powers, D. C.; Ritter, T. Palladium(III) in Synthesis and Catalysis (PDF). Topics in Organometallic Chemistry 35. 2011: 129–156. Bibcode:2011hoso.book..129P. ISBN 978-3-642-17428-5. PMC 3066514 . PMID 21461129. doi:10.1007/978-3-642-17429-2_6. （原始内容 (PDF)存档于June 12, 2013）. |journal=被忽略 (帮助)
Te(V)曾被Greenwood and Earnshaw提及，但他們沒有舉出任何Te(V)化合物的例子。而長久以來被認為是十氟化二碲（英语：Ditellurium decafluoride）（Te₂F₁₀）的物質實際上是雙(五氟碲基)氧化物：F₅TeOTeF₅，參見：Watkins, P. M. Ditellurium decafluoride - A Continuing Myth. Journal of Chemical Education. 1974, 51 (9): 520–521. Bibcode:1974JChEd..51..520W. doi:10.1021/ed051p520. 不過，Te(V)已在HTeO−
、TeO−
、HTeO−
2及TeO−
3中觀察到，參見：Kläning, Ulrik K.; Sehested, K. Tellurium(V). A Pulse Radiolysis Study. The Journal of Physical Chemistry A. 2001, 105 (27): 6637–45 [2023-05-28]. Bibcode:2001JPCA..105.6637K. doi:10.1021/jp010577i. （原始内容存档于2019-03-22）.
I(II)已知存在於一氧化物（IO）中，參見：Nikitin, I V. Halogen monoxides. Russian Chemical Reviews. 31 August 2008, 77 (8): 739–749. Bibcode:2008RuCRv..77..739N. doi:10.1070/RC2008v077n08ABEH003788.
Ba(I)已在一氟化鋇（BaF）中觀察到，參見：P. Colarusso; Guo, B.; Zhang, K.-Q.; Bernath, P.F.; et al. High-Resolution Fourier Transform Infrared Emission Spectrum of Barium Monofluoride (PDF). Journal of Molecular Spectroscopy. 1995, 170 (1): 59. Bibcode:1996JMoSp.175..158C. doi:10.1006/jmsp.1996.0019. （原始内容 (PDF)存档于2005-03-10）.
Ir(IX)已在IrO+
4中觀察到，參見：Wang, Guanjun; Zhou, Mingfei; Goettel, James T.; Schrobilgen, Gary G.; Su, Jing; Li, Jun; Schlöder, Tobias; Riedel, Sebastian. Identification of an iridium-containing compound with a formal oxidation state of IX. Nature. 21 August 2014, 514 (7523): 475–477. Bibcode:2014Natur.514..475W. PMID 25341786. S2CID 4463905. doi:10.1038/nature13795.
含Pb(0)的羰基錯合物已在鉛原子和一氧化碳間的反應中觀察到，參見：Ling, Jiang; Qiang, Xu. Observation of the lead carbonyls Pb_nCO (n=1–4): Reactions of lead atoms and small clusters with carbon monoxide in solid argon. The Journal of Chemical Physics. 122 (3): 034505. 2005, 122 (3): 34505 [2023-05-28]. Bibcode:2005JChPh.122c4505J. ISSN 0021-9606. PMID 15740207. doi:10.1063/1.1834915. （原始内容存档于2022-11-08）.
Rn(II)已在二氟化氡（RnF₂）中觀察到，參見：Stein, L. Ionic Radon Solution. Science. 1970, 168 (3929): 362–4. Bibcode:1970Sci...168..362S. PMID 17809133. S2CID 31959268. doi:10.1126/science.168.3929.362. and Kenneth S. Pitzer. Fluorides of radon and element 118. J. Chem. Soc., Chem. Commun. 1975, (18): 760b – 761 [2023-05-28]. doi:10.1039/C3975000760b. （原始内容存档于2021-12-08）.
Cm(VIII)曾被報告可能存在於四氧化鋦（CmO₄）中，參閱：Domanov, V. P. Possibility of generation of octavalent curium in the gas phase in the form of volatile tetraoxide CmO₄. Radiochemistry. January 2013, 55 (1): 46–51. S2CID 98076989. doi:10.1134/S1066362213010098. 然而，後續的實驗顯示該物質似乎不存在：Zaitsevskii, Andréi; Schwarz, W H Eugen. Structures and stability of AnO4 isomers, An = Pu, Am, and Cm: a relativistic density functional study. Physical Chemistry Chemical Physics. April 2014, 2014 (16): 8997–9001. Bibcode:2014PCCP...16.8997Z. PMID 24695756. doi:10.1039/c4cp00235k.
Sg(0)已在六羰基𨭎（Sg(CO)₆）中觀察到，參見：Even, J.; Yakushev, A.; Dullmann, C. E.; Haba, H.; Asai, M.; Sato, T. K.; Brand, H.; Di Nitto, A.; Eichler, R.; Fan, F. L.; Hartmann, W.; Huang, M.; Jager, E.; Kaji, D.; Kanaya, J.; Kaneya, Y.; Khuyagbaatar, J.; Kindler, B.; Kratz, J. V.; Krier, J.; Kudou, Y.; Kurz, N.; Lommel, B.; Miyashita, S.; Morimoto, K.; Morita, K.; Murakami, M.; Nagame, Y.; Nitsche, H.; et al. Synthesis and detection of a seaborgium carbonyl complex. Science. 2014, 345 (6203): 1491–3. Bibcode:2014Sci...345.1491E. PMID 25237098. S2CID 206558746. doi:10.1126/science.1255720.

chem.harvard.edu

Pd(III)已被觀察到，參見：Powers, D. C.; Ritter, T. Palladium(III) in Synthesis and Catalysis (PDF). Topics in Organometallic Chemistry 35. 2011: 129–156. Bibcode:2011hoso.book..129P. ISBN 978-3-642-17428-5. PMC 3066514 . PMID 21461129. doi:10.1007/978-3-642-17429-2_6. （原始内容 (PDF)存档于June 12, 2013）. |journal=被忽略 (帮助)

hull.ac.uk

www2.hull.ac.uk

Hg(IV)曾被報告發現存在於四氟化汞（HgF₄）中，參見：Xuefang Wang; Lester Andrews; Sebastian Riedel; Martin Kaupp. Mercury Is a Transition Metal: The First Experimental Evidence for HgF₄. Angew. Chem. Int. Ed. 2007, 46 (44): 8371–8375. PMID 17899620. doi:10.1002/anie.200703710. 但之後的實驗無法證實該發現，參閱：Is mercury a transition metal? 互联网档案馆的存檔，存档日期2016-10-12.

iaea.org

inis.iaea.org

Hf(I)已在一溴化鉿（HfBr）中觀察到，參見：Marek, G.S.; Troyanov, S.I.; Tsirel'nikov, V.I. Кристаллическое строение и термодинамические характеристики монобромидов циркония и гафния / Crystal structure and thermodynamic characteristics of monobromides of zirconium and hafnium. Журнал неорганической химии / Russian Journal of Inorganic Chemistry. 1979, 24 (4): 890–893 [2023-05-28]. （原始内容存档于2020-08-01）（俄语）.

nature.com

La(I)、Pr(I)、Tb(I)、Tm(I)及Yb(I)已在MB₈⁻簇合物中觀察到，參見：Li, Wan-Lu; Chen, Teng-Teng; Chen, Wei-Jia; Li, Jun; Wang, Lai-Sheng. Monovalent lanthanide(I) in borozene complexes. Nature Communications. 2021, 12: 6467 [2023-05-28]. doi:10.1038/s41467-021-26785-9. （原始内容存档于2022-09-26）.

nevada.edu

radchem.nevada.edu

Th(I)已知存在於溴化釷(I)（ThBr）中，參見：Wickleder, Mathias S.; Fourest, Blandine; Dorhout, Peter K. Thorium. Morss, Lester R.; Edelstein, Norman M.; Fuger, Jean (编). The Chemistry of the Actinide and Transactinide Elements (PDF) 3 3rd. Dordrecht, the Netherlands: Springer. 2006: 52–160. ISBN 978-1-4020-3555-5. doi:10.1007/1-4020-3598-5_3. （原始内容 (PDF)存档于2016-03-07）.

nih.gov

ncbi.nlm.nih.gov

已合成出在高壓下熱力學穩定的氦化鈉（(Na⁺)₂He(e^-)₂），參見：Dong, Xiao; Oganov, Artem R.; Goncharov, Alexander F.; Stavrou, Elissaios; Lobanov, Sergey; Saleh, Gabriele; Qian, Guang-Rui; Zhu, Qiang; Gatti, Carlo; Deringer, Volker L.; Dronskowski, Richard; Zhou, Xiang-Feng; Prakapenka, Vitali B.; Konôpková, Zuzana; Popov, Ivan A.; Boldyrev, Alexander I.; Wang, Hui-Tian. A stable compound of helium and sodium at high pressure. Nature Chemistry. 6 February 2017, 9 (5): 440–445. Bibcode:2017NatCh...9..440D. PMID 28430195. S2CID 20459726. arXiv:1309.3827 . doi:10.1038/nchem.2716.
Be(I)已在一氫化鈹（英语：Beryllium monohydride）（BeH）中觀察到，參見：Shayesteh, A.; Tereszchuk, K.; Bernath, P. F.; Colin, R. Infrared Emission Spectra of BeH and BeD (PDF). J. Chem. Phys. 2003, 118 (3): 1158 [2007-12-10]. Bibcode:2003JChPh.118.1158S. doi:10.1063/1.1528606. （原始内容 (PDF)存档于2007-12-02）. and in [(CAAC)₂Be]^+• [CAAC = cyclic (alkyl)(amino)carbene], see Wang, Guocang; Walley, Jacob E.; Dickie, Diane E.; Pan, Sudip; Frenking, Gernot; Gilliard Jr., Robert G. A Stable, Crystalline Beryllium Radical Cation. J. Am. Chem. Soc. 2020, 142 (10): 4560–4 [2020-11-17]. PMID 32088963. S2CID 211262005. doi:10.1021/jacs.9b13777. （原始内容存档于2022-09-24）.
B(0)已在雙硼炔（英语：diboryne）中觀察到，參見：Braunschweig, H.; Dewhurst, R. D.; Hammond, K.; Mies, J.; Radacki, K.; Vargas, A. Ambient-Temperature Isolation of a Compound with a Boron-Boron Triple Bond. Science. 2012, 336 (6087): 1420–2. Bibcode:2012Sci...336.1420B. PMID 22700924. S2CID 206540959. doi:10.1126/science.1221138.
七氟化金實際上是五氟化金與氟分子（F₂）形成的配合物。Himmel, Daniel; Riedel, Sebastian. After 20 Years, Theoretical Evidence That 'AuF₇' Is Actually AuF₅•F₂. Inorganic Chemistry. 2007, 46 (13): 5338–5342. PMID 17511450. doi:10.1021/ic700431s.
已知含有氦原子的SF₆⁺團簇中有氟(0)原子作為配基，參見：Albertini, Simon; Bergmeister, Stefan; Laimer, Felix; Martini, Paul; Gruber, Elisabeth; Zappa, Fabio; Ončák, Milan; Scheier, Paul; Echt, Olof. SF 6 + : Stabilizing Transient Ions in Helium Nanodroplets. The Journal of Physical Chemistry Letters. 2021-04-22, 12 (17): 4112–4117 [2023-05-28]. ISSN 1948-7185. PMC 8154854 . PMID 33886323. doi:10.1021/acs.jpclett.1c01024 . （原始内容存档于2022-09-24）（英语）.
實驗表明，氯化鈉在高壓下存在幾種不尋常的化學計量，例如Na₃Cl，其中包含一層Na(0)原子，參見：Zhang, W.; Oganov, A. R.; Goncharov, A. F.; Zhu, Q.; Boulfelfel, S. E.; Lyakhov, A. O.; Stavrou, E.; Somayazulu, M.; Prakapenka, V. B.; Konôpková, Z. Unexpected Stable Stoichiometries of Sodium Chlorides. Science. 2013, 342 (6165): 1502–1505. Bibcode:2013Sci...342.1502Z. PMID 24357316. S2CID 15298372. arXiv:1310.7674 . doi:10.1126/science.1244989.
Mg(0)已在Na₂Mg₂²⁺團簇與龐大有機配體配位形成的絡合物中觀察到，參見：Rösch, B.; Gentner, T. X.; Eyselein, J.; Langer, J.; Elsen, H.; Li, W.; Harder, S. Strongly reducing magnesium(0) complexes. Nature. 2021, 592 (7856): 717–721. Bibcode:2021Natur.592..717R. PMID 33911274. S2CID 233447380. doi:10.1038/s41586-021-03401-w
含有Mg(I)的低價鎂化合物已使用大陰離子配體製得，參見：Green, S. P.; Jones C.; Stasch A. Stable Magnesium(I) Compounds with Mg-Mg Bonds. Science. December 2007, 318 (5857): 1754–1757. Bibcode:2007Sci...318.1754G. PMID 17991827. S2CID 40657565. doi:10.1126/science.1150856.
P(0)已被觀察到，參見：Wang, Yuzhong; Xie, Yaoming; Wei, Pingrong; King, R. Bruce; Schaefer, Iii; Schleyer, Paul v. R.; Robinson, Gregory H. Carbene-Stabilized Diphosphorus. Journal of the American Chemical Society. 2008, 130 (45): 14970–1. PMID 18937460. doi:10.1021/ja807828t.
已在以氖作為基質的隔離（英语：Matrix isolation）下觀察到鈣、鍶、鋇的八羰基配合物，但尚不清楚這些是否為其0價態配合物，因為計算結果否定了配合物中金屬原子和配體形成共價鍵或離子鍵與否，參見：Wu, X.; Zhao, L.; Jin, J.; Pan, S.; Li, W.; Jin, X.; Wang, G.; Zhou, M.; Frenking, G. Observation of alkaline earth complexes M(CO)8 (M = Ca, Sr, or Ba) that mimic transition metals. Science. 2018, 361 (6405): 912–916. Bibcode:2018Sci...361..912W. PMID 30166489. S2CID 52131470. doi:10.1126/science.aau0839
Ca(I)已被觀察到，參見：Krieck, Sven; Görls, Helmar; Westerhausen, Matthias. Mechanistic Elucidation of the Formation of the Inverse Ca(I) Sandwich Complex [(thf)₃Ca(μ-C₆H₃-1,3,5-Ph₃)Ca(thf)₃] and Stability of Aryl-Substituted Phenylcalcium Complexes. Journal of the American Chemical Society. 2010, 132 (35): 12492–501. PMID 20718434. doi:10.1021/ja105534w.
Sc(II)已被觀察到，參見：Woen, David H.; Chen, Guo P.; Ziller, Joseph W.; Boyle, Timothy J.; Furche, Filipp; Evans, William J. Solution Synthesis, Structure, and CO Reduction Reactivity of a Scandium(II) Complex. Angewandte Chemie International Edition. January 2017, 56 (8): 2050–2053. PMID 28097771. doi:10.1002/anie.201611758.
Ti(−1)最初被報告存在於[Ti(bipy)₃]⁻ 中，但後來證明其為Ti(+3)，參見Bowman, A. C.; England, J.; Sprouls, S.; Weihemüller, T.; Wieghardt, K. Electronic structures of homoleptic [tris(2,2'-bipyridine)M]n complexes of the early transition metals (M = Sc, Y, Ti, Zr, Hf, V, Nb, Ta; n = 1+, 0, 1-, 2-, 3-): an experimental and density functional theoretical study. Inorganic Chemistry. 2013, 52 (4): 2242–56. PMID 23387926. doi:10.1021/ic302799s. 不過，Ti(−1)被發現存在於[Ti(η-C₆H₆]⁻和[Ti(η-C₆H₅CH₃)]⁻中, 參見：Bandy, J. A.; Berry, A.; Green, M. L. H.; Perutz, R. N.; Prout, K.; Verpeautz, J.-N. Synthesis of anionic sandwich compounds: [Ti(η-C₆H₅R)₂]^– and the crystal structure of [K(18-crown-6)(µ-H)Mo(η-C₅H₅)₂]. Inorganic Chemistry. 1984, 52 (4): 729–731. doi:10.1039/C39840000729.
Jilek, Robert E.; Tripepi, Giovanna; Urnezius, Eugenijus; Brennessel, William W.; Young, Victor G. Jr.; Ellis, John E. Zerovalent titanium–sulfur complexes. Novel dithiocarbamato derivatives of Ti(CO)₆: [Ti(CO)₄(S₂CNR₂)]⁻. Chem. Commun. 2007, (25): 2639–2641. PMID 17579764. doi:10.1039/B700808B.
Fe(VII)已在[FeO₄]⁻中觀察到，參見：Lu, Jun-Bo; Jian, Jiwen; Huang, Wei; Lin, Hailu; Zhou, Mingfei. Experimental and theoretical identification of the Fe(VII) oxidation state in FeO₄⁻. Physical Chemistry Chemical Physics. 2016, 18 (45): 31125–31131. Bibcode:2016PCCP...1831125L. PMID 27812577. doi:10.1039/C6CP06753K.
Ni(−2)已在Li₂[Ni(1,5-COD)₂]中觀察到，參見：Jonas, Klaus. Dilithium-Nickel-Olefin Complexes. Novel Bimetal Complexes Containing a Transition Metal and a Main Group Metal. Angew. Chem. Int. Ed. 1975, 14 (11): 752–753. doi:10.1002/anie.197507521. and Ellis, John E. Adventures with Substances Containing Metals in Negative Oxidation States. Inorganic Chemistry. 2006, 45 (8): 3167–86. PMID 16602773. doi:10.1021/ic052110i.
Cu(0)已在Cu(tris[2-(diisopropylphosphino)-phenyl]borane)中觀察到，參見：Moret, Marc-Etienne; Zhang, Limei; Peters, Jonas C. A Polar Copper–Boron One-Electron σ-Bond. J. Am. Chem. Soc. 2013, 135 (10): 3792–3795 [2023-05-28]. PMID 23418750. doi:10.1021/ja4006578. （原始内容存档于2022-10-07）.
Zn(0)已被觀察到，參見：Singh, Amit Pratap; Samuel, Prinson P.; Roesky, Herbert W.; Schwarzer, Martin C.; Frenking, Gernot; Sidhu, Navdeep S.; Dittrich, Birger. A Singlet Biradicaloid Zinc Compound and Its Nonradical Counterpart. J. Am. Chem. Soc. 2013, 135 (19): 7324–9. PMID 23600486. doi:10.1021/ja402351x. and Soleilhavoup, Michèle; Bertrand, Guy. Cyclic (Alkyl)(Amino)Carbenes (CAACs): Stable Carbenes on the Rise. Acc. Chem. Res. 2015, 48 (2): 256–266. PMID 25515548. doi:10.1021/ar5003494.
Zn(I)已在二(五甲基環戊二烯)基鋅（英语：decamethyldizincocene）（Zn₂(η⁵–C₅Me₅)₂）中觀察到，參見：Resa, I.; Carmona, E.; Gutierrez-Puebla, E.; Monge, A. Decamethyldizincocene, a Stable Compound of Zn(I) with a Zn-Zn Bond. Science. 2004, 305 (5687): 1136–8. Bibcode:2004Sci...305.1136R. PMID 15326350. S2CID 38990338. doi:10.1126/science.1101356.
據預測，Zn(III)在具有高度穩定性的基於硼烷的三元離子化合物中是穩定的，但目前在實驗中尚無已知的Zn(III)候選物質，參見：Hong Fang; Huta Banjade; Deepika; Puru Jena. Realization of the Zn3+ oxidation state. Nanoscale. 2021, 13 (33): 14041–14048. PMID 34477685. S2CID 237400349. doi:10.1039/D1NR02816B （英语）.
As(0)已被觀察到，參見：Abraham, Mariham Y.; Wang, Yuzhong; Xie, Yaoming; Wei, Pingrong; Shaefer III, Henry F.; Schleyer, P. von R.; Robinson, Gregory H. Carbene Stabilization of Diarsenic: From Hypervalency to Allotropy. Chemistry: A European Journal. 2010, 16 (2): 432–5. PMID 19937872. doi:10.1002/chem.200902840.
As(I)已在AsI中觀察到，參見：Ellis, Bobby D.; MacDonald, Charles L. B. Stabilized Arsenic(I) Iodide: A Ready Source of Arsenic Iodide Fragments and a Useful Reagent for the Generation of Clusters. Inorganic Chemistry. 2004, 43 (19): 5981–6. PMID 15360247. doi:10.1021/ic049281s.
Y(II)已在[(18-crown-6)K][(C₅H₄SiMe₃)₃Y]中觀察到，參見：MacDonald, M. R.; Ziller, J. W.; Evans, W. J. Synthesis of a Crystalline Molecular Complex of Y²⁺, [(18-crown-6)K][(C₅H₄SiMe₃)₃Y]. J. Am. Chem. Soc. 2011, 133 (40): 15914–17. PMID 21919538. doi:10.1021/ja207151y.
Zr(−1)曾被報告存在於[Zr(bipy)₃]⁻中（參見 Greenwood, N. N.; Earnshaw, A. Chemistry of the Elements 2nd. Oxford:Butterworth-Heinemann. 1997: 960. ISBN 0-7506-3365-4. 及 Holleman, Arnold F.; Wiberg, Egon; Wiberg, Nils. Zirconium. Lehrbuch der Anorganischen Chemie 101. Walter de Gruyter. 1995: 1413. ISBN 978-3-11-012641-9 （德语）. ）, 但後來被證明是Zr(+4)，參見：Bowman, A. C.; England, J.; Sprouls, S.; Weihemüller, T.; Wieghardt, K. Electronic structures of homoleptic [tris(2,2'-bipyridine)M]n complexes of the early transition metals (M = Sc, Y, Ti, Zr, Hf, V, Nb, Ta; n = 1+, 0, 1-, 2-, 3-): an experimental and density functional theoretical study. Inorganic Chemistry. 2013, 52 (4): 2242–56. PMID 23387926. doi:10.1021/ic302799s.
Pd(I)已被觀察到，參見：Crabtree, R. H. CHEMISTRY: A New Oxidation State for Pd?. Science. 2002, 295 (5553): 288–289. PMID 11786632. S2CID 94579227. doi:10.1126/science.1067921.
Pd(III)已被觀察到，參見：Powers, D. C.; Ritter, T. Palladium(III) in Synthesis and Catalysis (PDF). Topics in Organometallic Chemistry 35. 2011: 129–156. Bibcode:2011hoso.book..129P. ISBN 978-3-642-17428-5. PMC 3066514 . PMID 21461129. doi:10.1007/978-3-642-17429-2_6. （原始内容 (PDF)存档于June 12, 2013）. |journal=被忽略 (帮助)
In(–5)已在La₃InGe中觀察到，參見：Guloy, A. M.; Corbett, J. D. Synthesis, Structure, and Bonding of Two Lanthanum Indium Germanides with Novel Structures and Properties. Inorganic Chemistry. 1996, 35 (9): 2616–22. PMID 11666477. doi:10.1021/ic951378e.
Sb(I)及Sb(II)已在有機銻化合物中觀察到；關於Sb(I)，參見：Šimon, Petr; de Proft, Frank; Jambor, Roman; Růžička, Aleš; Dostál, Libor. Monomeric Organoantimony(I) and Organobismuth(I) Compounds Stabilized by an NCN Chelating Ligand: Syntheses and Structures. Angewandte Chemie International Edition. 2010, 49 (32): 5468–5471. PMID 20602393. doi:10.1002/anie.201002209.
Pr(I)已在[PrB₄]⁻中觀察到，參見：Chen, Xin; Chen, Teng-Teng; Li, Wang-Lu; Lu, Jun-Bo; Zhao, Li-Juan; Jian, Tian; Hu, Han-Shi; Wang, Lai-Sheng; Li, Jun. Lanthanides with Unusually Low Oxidation States in the PrB₃^– and PrB₄^– Boride Clusters. Inorganic Chemistry. 2018-12-13, 58 (1): 411–418. PMID 30543295. S2CID 56148031. doi:10.1021/acs.inorgchem.8b02572.
Pr(V)已在[PrO₂]⁺中觀察到，參見：Zhang, Qingnan; Hu, Shu-Xian; Qu, Hui; Su, Jing; Wang, Guanjun; Lu, Jun-Bo; Chen, Mohua; Zhou, Mingfei; Li, Jun. Pentavalent Lanthanide Compounds: Formation and Characterization of Praseodymium(V) Oxides. Angewandte Chemie International Edition. 2016-06-06, 55 (24): 6896–6900. ISSN 1521-3773. PMID 27100273. doi:10.1002/anie.201602196.
Hu, Shu-Xian; Jian, Jiwen; Su, Jing; Wu, Xuan; Li, Jun; Zhou, Mingfei. Pentavalent lanthanide nitride-oxides: NPrO and NPrO− complexes with N≡Pr triple bonds. Chemical Science. 2017, 8 (5): 4035–4043. ISSN 2041-6520. PMC 5434915 . PMID 28580119. doi:10.1039/C7SC00710H （英语）.
所有鑭系元素（鑭至鎦）的+2氧化態均已在其二鹵化物和鹼土金屬二鹵化物形成的稀固溶體中（參閱：Holleman, Arnold Frederik; Wiberg, Egon, Wiberg, Nils , 编, Inorganic Chemistry, 由Eagleson, Mary; Brewer, William翻译, San Diego/Berlin: Academic Press/De Gruyter, 2001, ISBN 0-12-352651-5 ，鑭、釓、鎦除外）以及其有機金屬分子錯合物中（鉕除外）觀察到，參見：Lanthanides Topple Assumptions （页面存档备份，存于互联网档案馆） and Meyer, G. All the Lanthanides Do It and Even Uranium Does Oxidation State +2. Angewandte Chemie International Edition. 2014, 53 (14): 3550–51. PMID 24616202. doi:10.1002/anie.201311325. 。此外，雖然所有鑭系元素皆形成二氫化物（LnH₂）、二碳化物（LnC₂）、一硫化物（LnS）、一硒化物（LnSe）和一碲化物（LnTe），但對於大多數鑭系元素，這些化合物中的鑭系離子實為+3態，伴隨著離域至導帶的電子，例如：Ln³⁺(H⁻)₂(e⁻)。
Ir(VIII)已在四氧化銥（IrO₄）中觀察到，參見：Gong, Yu; Zhou, Mingfei; Kaupp, Martin; Riedel, Sebastian. Formation and Characterization of the Iridium Tetroxide Molecule with Iridium in the Oxidation State +VIII. Angewandte Chemie International Edition. 2009, 48 (42): 7879–7883. PMID 19593837. doi:10.1002/anie.200902733.
Ir(IX)已在IrO+
4中觀察到，參見：Wang, Guanjun; Zhou, Mingfei; Goettel, James T.; Schrobilgen, Gary G.; Su, Jing; Li, Jun; Schlöder, Tobias; Riedel, Sebastian. Identification of an iridium-containing compound with a formal oxidation state of IX. Nature. 21 August 2014, 514 (7523): 475–477. Bibcode:2014Natur.514..475W. PMID 25341786. S2CID 4463905. doi:10.1038/nature13795.
Pt(−1)及Pt(−2)已分別在鋇的鉑化物BaPt及Ba₂Pt中觀察到，參見：Karpov, Andrey; Konuma, Mitsuharu; Jansen, Martin. An experimental proof for negative oxidation states of platinum: ESCA-measurements on barium platinides. Chemical Communications. 2006, (8): 838–840. PMID 16479284. doi:10.1039/b514631c.
Au(0)已被觀察到，參見：Mézaille, Nicolas; Avarvari, Narcis; Maigrot, Nicole; Ricard, Louis; Mathey, François; Le Floch, Pascal; Cataldo, Laurent; Berclaz, Théo; Geoffroy, Michel. Gold(I) and Gold(0) Complexes of Phosphinine‐Based Macrocycles. Angewandte Chemie International Edition. 1999, 38 (21): 3194–3197. PMID 10556900. doi:10.1002/(SICI)1521-3773(19991102)38:21<3194::AID-ANIE3194>3.0.CO;2-O.
Hg(IV)曾被報告發現存在於四氟化汞（HgF₄）中，參見：Xuefang Wang; Lester Andrews; Sebastian Riedel; Martin Kaupp. Mercury Is a Transition Metal: The First Experimental Evidence for HgF₄. Angew. Chem. Int. Ed. 2007, 46 (44): 8371–8375. PMID 17899620. doi:10.1002/anie.200703710. 但之後的實驗無法證實該發現，參閱：Is mercury a transition metal? 互联网档案馆的存檔，存档日期2016-10-12.
Tl(−5)已在Na₂₃K₉Tl_15.3中觀察到，參見：Dong, Z.-C.; Corbett, J. D. Na₂₃K₉Tl_15.3: An Unusual Zintl Compound Containing Apparent Tl₅⁷⁻, Tl₄⁸⁻, Tl₃⁷⁻, and Tl⁵⁻ Anions. Inorganic Chemistry. 1996, 35 (11): 3107–12. PMID 11666505. doi:10.1021/ic960014z.
含Pb(0)的羰基錯合物已在鉛原子和一氧化碳間的反應中觀察到，參見：Ling, Jiang; Qiang, Xu. Observation of the lead carbonyls Pb_nCO (n=1–4): Reactions of lead atoms and small clusters with carbon monoxide in solid argon. The Journal of Chemical Physics. 122 (3): 034505. 2005, 122 (3): 34505 [2023-05-28]. Bibcode:2005JChPh.122c4505J. ISSN 0021-9606. PMID 15740207. doi:10.1063/1.1834915. （原始内容存档于2022-11-08）.
Pb(+1)及Pb(+3)已在有機鉛化合物中觀察到，如六甲基二鉛烷（Pb₂(CH₃)₆）等；有關Pb(I)的資訊，參閱：Siew-Peng Chia; Hong-Wei Xi; Yongxin Li; Kok Hwa Lim; Cheuk-Wai So. A Base-Stabilized Lead(I) Dimer and an Aromatic Plumbylidenide Anion. Angew. Chem. Int. Ed. 2013, 52 (24): 6298–6301. PMID 23629949. doi:10.1002/anie.201301954.
Rn(II)已在二氟化氡（RnF₂）中觀察到，參見：Stein, L. Ionic Radon Solution. Science. 1970, 168 (3929): 362–4. Bibcode:1970Sci...168..362S. PMID 17809133. S2CID 31959268. doi:10.1126/science.168.3929.362. and Kenneth S. Pitzer. Fluorides of radon and element 118. J. Chem. Soc., Chem. Commun. 1975, (18): 760b – 761 [2023-05-28]. doi:10.1039/C3975000760b. （原始内容存档于2021-12-08）.
Th(-I)及U(-I)已在氣相中以八羰基陰離子的形式被檢測到，參見：Chaoxian, Chi; Sudip, Pan; Jiaye, Jin; Luyan, Meng; Mingbiao, Luo; Lili, Zhao; Mingfei, Zhou; Gernot, Frenking. Octacarbonyl Ion Complexes of Actinides [An(CO)₈]^+/− (An=Th, U) and the Role of f Orbitals in Metal–Ligand Bonding. Chemistry (Weinheim an der Bergstrasse, Germany). 25 (50): 11772–11784. 2019, 25 (50): 11772–11784. ISSN 0947-6539. PMC 6772027 . PMID 31276242. doi:10.1002/chem.201902625.
Th(II)及Th(III)已在[Th^II{η⁵-C₅H₃(SiMe₃)₂}₃]⁻及[Th^III{η⁵-C₅H₃(SiMe₃)₂}₃]中觀察到，參見：Langeslay, Ryan R.; Fieser, Megan E.; Ziller, Joseph W.; Furche, Philip; Evans, William J. Synthesis, structure, and reactivity of crystalline molecular complexes of the {[C₅H₃(SiMe₃)₂]₃Th}¹⁻ anion containing thorium in the formal +2 oxidation state. Chem. Sci. 2015, 6 (1): 517–521. PMC 5811171 . PMID 29560172. doi:10.1039/C4SC03033H.
Th(-I)及U(-I)已在氣相中以八羰基陰離子的形式被檢測到，參見：Chaoxian, Chi; Sudip, Pan; Jiaye, Jin; Luyan, Meng; Mingbiao, Luo; Lili, Zhao; Mingfei, Zhou; Gernot, Frenking. Octacarbonyl Ion Complexes of Actinides [An(CO)₈]^+/− (An=Th, U) and the Role of f Orbitals in Metal–Ligand Bonding. Chemistry (Weinheim an der Bergstrasse, Germany). 25 (50): 11772–11784. 2019, 25 (50): 11772–11784. ISSN 0947-6539. PMC 6772027 . PMID 31276242. doi:10.1002/chem.201902625.
U(II)已在[K(2.2.2-Cryptand)][(C₅H₄SiMe₃)₃U]中觀察到，參見：MacDonald, Matthew R.; Fieser, Megan E.; Bates, Jefferson E.; Ziller, Joseph W.; Furche, Filipp; Evans, William J. Identification of the +2 Oxidation State for Uranium in a Crystalline Molecular Complex, [K(2.2.2-Cryptand)][(C₅H₄SiMe₃)₃U]. J. Am. Chem. Soc. 2013, 135 (36): 13310–13313. PMID 23984753. doi:10.1021/ja406791t.
Np(II)、Np(III)及Np(IV)已被觀察到，參見：Dutkiewicz, Michał S.; Apostolidis, Christos; Walter, Olaf; Arnold, Polly L. Reduction chemistry of neptunium cyclopentadienide complexes: from structure to understanding. Chem. Sci. 2017, 8 (4): 2553–2561. PMC 5431675 . PMID 28553487. doi:10.1039/C7SC00034K.
Pu(II)已在{Pu[C₅H₃(SiMe₃)₂]₃}−中觀察到，參見：Windorff, Cory J.; Chen, Guo P; Cross, Justin N; Evans, William J.; Furche, Filipp; Gaunt, Andrew J.; Janicke, Michael T.; Kozimor, Stosh A.; Scott, Brian L. Identification of the Formal +2 Oxidation State of Plutonium: Synthesis and Characterization ofref name="curium5" {Pu^II[C₅H₃(SiMe₃)₂]₃}−. J. Am. Chem. Soc. 2017, 139 (11): 3970–3973. PMID 28235179. doi:10.1021/jacs.7b00706.
Cm(V)、Bk(V)及Cf(V)已在BkO₂⁺、CfO₂⁺、CmO₂(NO₃)₂⁻、BkO₂(NO₃)₂⁻及CfO₂(NO₃)₂⁻中觀察到，參見：Dau, Phuong Diem; Vasiliu, Monica; Peterson, Kirk A; Dixon, David A; Gibsoon, John K. Remarkably High Stability of Late Actinide Dioxide Cations: Extending Chemistry to Pentavalent Berkelium and Californium. Chemistry - A European Journal. October 2017, 23 (68): 17369–17378 [2023-05-28]. PMID 29024093. doi:10.1002/chem.201704193. （原始内容存档于2023-03-26）.
Kovács, Attila; Dau, Phuong D.; Marçalo, Joaquim; Gibson, John K. Pentavalent Curium, Berkelium, and Californium in Nitrate Complexes: Extending Actinide Chemistry and Oxidation States. Inorg. Chem. (American Chemical Society). 2018, 57 (15): 9453–9467. OSTI 1631597. PMID 30040397. S2CID 51717837. doi:10.1021/acs.inorgchem.8b01450.
Cm(VIII)曾被報告可能存在於四氧化鋦（CmO₄）中，參閱：Domanov, V. P. Possibility of generation of octavalent curium in the gas phase in the form of volatile tetraoxide CmO₄. Radiochemistry. January 2013, 55 (1): 46–51. S2CID 98076989. doi:10.1134/S1066362213010098. 然而，後續的實驗顯示該物質似乎不存在：Zaitsevskii, Andréi; Schwarz, W H Eugen. Structures and stability of AnO4 isomers, An = Pu, Am, and Cm: a relativistic density functional study. Physical Chemistry Chemical Physics. April 2014, 2014 (16): 8997–9001. Bibcode:2014PCCP...16.8997Z. PMID 24695756. doi:10.1039/c4cp00235k.
Sg(0)已在六羰基𨭎（Sg(CO)₆）中觀察到，參見：Even, J.; Yakushev, A.; Dullmann, C. E.; Haba, H.; Asai, M.; Sato, T. K.; Brand, H.; Di Nitto, A.; Eichler, R.; Fan, F. L.; Hartmann, W.; Huang, M.; Jager, E.; Kaji, D.; Kanaya, J.; Kaneya, Y.; Khuyagbaatar, J.; Kindler, B.; Kratz, J. V.; Krier, J.; Kudou, Y.; Kurz, N.; Lommel, B.; Miyashita, S.; Morimoto, K.; Morita, K.; Murakami, M.; Nagame, Y.; Nitsche, H.; et al. Synthesis and detection of a seaborgium carbonyl complex. Science. 2014, 345 (6203): 1491–3. Bibcode:2014Sci...345.1491E. PMID 25237098. S2CID 206558746. doi:10.1126/science.1255720.

openmopac.net

Y(I)已在YBr中觀察到，參見：Yttrium: yttrium(I) bromide compound data. OpenMOPAC.net. [2007-12-10]. （原始内容存档于2011-07-23）.

osti.gov

不穩定的Al(0)羰基配合物已在三甲基鋁（Al₂(CH₃)₆）與一氧化碳的反應中檢測到，參見：Sanchez, Ramiro; Arrington, Caleb; Arrington Jr., C. A. Reaction of trimethylaluminum with carbon monoxide in low-temperature matrixes. American Chemical Society. December 1, 1989, 111 (25): 9110-9111. doi:10.1021/ja00207a023.
Kovács, Attila; Dau, Phuong D.; Marçalo, Joaquim; Gibson, John K. Pentavalent Curium, Berkelium, and Californium in Nitrate Complexes: Extending Actinide Chemistry and Oxidation States. Inorg. Chem. (American Chemical Society). 2018, 57 (15): 9453–9467. OSTI 1631597. PMID 30040397. S2CID 51717837. doi:10.1021/acs.inorgchem.8b01450.

psi.ch

lch.web.psi.ch

Db(V)已在五氯化𨧀（DbCl₅）中觀察到，參見：H. W. Gäggeler. Gas Phase Chemistry of Superheavy Elements (PDF). Paul Scherrer Institute: 26–28. 2007. （原始内容 (PDF)存档于2012-02-20）.

psi.ch

Cn(II)已在硒化鎶（CnSe）中觀察到，參見：Annual Report 2015: Laboratory of Radiochemistry and Environmental Chemistry (PDF). Paul Scherrer Institute: 3. 2015 [2023-05-28]. （原始内容存档 (PDF)于2016-12-20）.

researchgate.net

不穩定的In(0)羰基錯合物和團簇已被檢測到，參見：[6] （页面存档备份，存于互联网档案馆）, p. 6.
Sn(−3)已在[Sn₂]⁶⁻中觀察到，例如在(Ba₂)⁴⁺(Mg₄)⁸⁺Sn⁴⁻(Sn₂)⁶⁻Sn²⁻中（其中有正方形層狀(Sn²⁻)_n），參見：Papoian, Garegin A.; Hoffmann, Roald. Hypervalent Bonding in One, Two, and Three Dimensions: Extending the Zintl–Klemm Concept to Nonclassical Electron-Rich Networks. Angew. Chem. Int. Ed. 2000, 2000 (39): 2408–2448 [2015-02-23]. doi:10.1002/1521-3773(20000717)39:14<2408::aid-anie2408>3.0.co;2-u. （原始内容存档于2018-10-26）.
Te(III)已在[Te(N(SiMe₃)₂)₂]⁺中觀察到，參見：Heinze, Thorsten; Roesky, Herbert W.; Pauer, Frank; Stalke, Dietmar; Sheldrick, George M. Synthesis and Structure of the First Tellurium(III) Radical Cation. Angewandte Chemie International Edition. 1991, 30 (12): 1678 [2015-02-23]. doi:10.1002/anie.199116771. （原始内容存档于2018-09-19）.

rsc.org

pubs.rsc.org

Li(0)原子已在多種氯化鋰小團簇中觀察到，參見：Milovanović, Milan; Veličković, Suzana; Veljkovićb, Filip; Jerosimić, Stanka. Structure and stability of small lithium-chloride Li_nCl_m^(0,1+) (n ≥ m, n = 1–6, m = 1–3) clusters. Physical Chemistry Chemical Physics. October 30, 2017, (45) [2023-05-28]. doi:10.1039/C7CP04181K. （原始内容存档于2022-09-22）.

scitation.org

aip.scitation.org

含Pb(0)的羰基錯合物已在鉛原子和一氧化碳間的反應中觀察到，參見：Ling, Jiang; Qiang, Xu. Observation of the lead carbonyls Pb_nCO (n=1–4): Reactions of lead atoms and small clusters with carbon monoxide in solid argon. The Journal of Chemical Physics. 122 (3): 034505. 2005, 122 (3): 34505 [2023-05-28]. Bibcode:2005JChPh.122c4505J. ISSN 0021-9606. PMID 15740207. doi:10.1063/1.1834915. （原始内容存档于2022-11-08）.

semanticscholar.org

api.semanticscholar.org

已合成出在高壓下熱力學穩定的氦化鈉（(Na⁺)₂He(e^-)₂），參見：Dong, Xiao; Oganov, Artem R.; Goncharov, Alexander F.; Stavrou, Elissaios; Lobanov, Sergey; Saleh, Gabriele; Qian, Guang-Rui; Zhu, Qiang; Gatti, Carlo; Deringer, Volker L.; Dronskowski, Richard; Zhou, Xiang-Feng; Prakapenka, Vitali B.; Konôpková, Zuzana; Popov, Ivan A.; Boldyrev, Alexander I.; Wang, Hui-Tian. A stable compound of helium and sodium at high pressure. Nature Chemistry. 6 February 2017, 9 (5): 440–445. Bibcode:2017NatCh...9..440D. PMID 28430195. S2CID 20459726. arXiv:1309.3827 . doi:10.1038/nchem.2716.
Be(I)已在一氫化鈹（英语：Beryllium monohydride）（BeH）中觀察到，參見：Shayesteh, A.; Tereszchuk, K.; Bernath, P. F.; Colin, R. Infrared Emission Spectra of BeH and BeD (PDF). J. Chem. Phys. 2003, 118 (3): 1158 [2007-12-10]. Bibcode:2003JChPh.118.1158S. doi:10.1063/1.1528606. （原始内容 (PDF)存档于2007-12-02）. and in [(CAAC)₂Be]^+• [CAAC = cyclic (alkyl)(amino)carbene], see Wang, Guocang; Walley, Jacob E.; Dickie, Diane E.; Pan, Sudip; Frenking, Gernot; Gilliard Jr., Robert G. A Stable, Crystalline Beryllium Radical Cation. J. Am. Chem. Soc. 2020, 142 (10): 4560–4 [2020-11-17]. PMID 32088963. S2CID 211262005. doi:10.1021/jacs.9b13777. （原始内容存档于2022-09-24）.
B(0)已在雙硼炔（英语：diboryne）中觀察到，參見：Braunschweig, H.; Dewhurst, R. D.; Hammond, K.; Mies, J.; Radacki, K.; Vargas, A. Ambient-Temperature Isolation of a Compound with a Boron-Boron Triple Bond. Science. 2012, 336 (6087): 1420–2. Bibcode:2012Sci...336.1420B. PMID 22700924. S2CID 206540959. doi:10.1126/science.1221138.
實驗表明，氯化鈉在高壓下存在幾種不尋常的化學計量，例如Na₃Cl，其中包含一層Na(0)原子，參見：Zhang, W.; Oganov, A. R.; Goncharov, A. F.; Zhu, Q.; Boulfelfel, S. E.; Lyakhov, A. O.; Stavrou, E.; Somayazulu, M.; Prakapenka, V. B.; Konôpková, Z. Unexpected Stable Stoichiometries of Sodium Chlorides. Science. 2013, 342 (6165): 1502–1505. Bibcode:2013Sci...342.1502Z. PMID 24357316. S2CID 15298372. arXiv:1310.7674 . doi:10.1126/science.1244989.
Mg(0)已在Na₂Mg₂²⁺團簇與龐大有機配體配位形成的絡合物中觀察到，參見：Rösch, B.; Gentner, T. X.; Eyselein, J.; Langer, J.; Elsen, H.; Li, W.; Harder, S. Strongly reducing magnesium(0) complexes. Nature. 2021, 592 (7856): 717–721. Bibcode:2021Natur.592..717R. PMID 33911274. S2CID 233447380. doi:10.1038/s41586-021-03401-w
含有Mg(I)的低價鎂化合物已使用大陰離子配體製得，參見：Green, S. P.; Jones C.; Stasch A. Stable Magnesium(I) Compounds with Mg-Mg Bonds. Science. December 2007, 318 (5857): 1754–1757. Bibcode:2007Sci...318.1754G. PMID 17991827. S2CID 40657565. doi:10.1126/science.1150856.
Al(−2)已在Sr₁₄[Al₄]₂[Ge]₃中觀察到，參見：Wemdorff, Marco; Röhr, Caroline. Sr₁₄[Al₄]₂[Ge]₃: Eine Zintl-Phase mit isolierten [Ge]^4–- und [Al₄]^8–-Anionen / Sr₁₄[Al₄]₂[Ge]₃: A Zintl Phase with Isolated [Ge]^4–- and [Al₄]^8– Anions. Zeitschrift für Naturforschung B. 2007, 62 (10): 1227. S2CID 94972243. doi:10.1515/znb-2007-1001 （德语）.
Al(II)已在一氧化鋁（AlO）中觀察到，參見：Tyte, D.C. Red (B2Π–A2σ) Band System of Aluminium Monoxide. Nature. 1964, 202 (4930): 383–384. Bibcode:1964Natur.202..383T. S2CID 4163250. doi:10.1038/202383a0 , and in dialanes (R₂Al—AlR₂); see Uhl, Werner. Organoelement Compounds Possessing Al—Al, Ga—Ga, In—In, and Tl—Tl Single Bonds. Advances in Organometallic Chemistry. 2004, 51: 53–108. doi:10.1016/S0065-3055(03)51002-4.
已在以氖作為基質的隔離（英语：Matrix isolation）下觀察到鈣、鍶、鋇的八羰基配合物，但尚不清楚這些是否為其0價態配合物，因為計算結果否定了配合物中金屬原子和配體形成共價鍵或離子鍵與否，參見：Wu, X.; Zhao, L.; Jin, J.; Pan, S.; Li, W.; Jin, X.; Wang, G.; Zhou, M.; Frenking, G. Observation of alkaline earth complexes M(CO)8 (M = Ca, Sr, or Ba) that mimic transition metals. Science. 2018, 361 (6405): 912–916. Bibcode:2018Sci...361..912W. PMID 30166489. S2CID 52131470. doi:10.1126/science.aau0839
Zn(I)已在二(五甲基環戊二烯)基鋅（英语：decamethyldizincocene）（Zn₂(η⁵–C₅Me₅)₂）中觀察到，參見：Resa, I.; Carmona, E.; Gutierrez-Puebla, E.; Monge, A. Decamethyldizincocene, a Stable Compound of Zn(I) with a Zn-Zn Bond. Science. 2004, 305 (5687): 1136–8. Bibcode:2004Sci...305.1136R. PMID 15326350. S2CID 38990338. doi:10.1126/science.1101356.
據預測，Zn(III)在具有高度穩定性的基於硼烷的三元離子化合物中是穩定的，但目前在實驗中尚無已知的Zn(III)候選物質，參見：Hong Fang; Huta Banjade; Deepika; Puru Jena. Realization of the Zn3+ oxidation state. Nanoscale. 2021, 13 (33): 14041–14048. PMID 34477685. S2CID 237400349. doi:10.1039/D1NR02816B （英语）.
Pd(I)已被觀察到，參見：Crabtree, R. H. CHEMISTRY: A New Oxidation State for Pd?. Science. 2002, 295 (5553): 288–289. PMID 11786632. S2CID 94579227. doi:10.1126/science.1067921.
Sb(0)已被觀察到，參見：Anastas Sidiropoulos. Studies of N-heterocyclic Carbene (NHC) Complexes of the Main Group Elements (PDF). : 39 [2023-05-28]. S2CID 132399530. doi:10.4225/03/5B0F4BDF98F60. （原始内容存档 (PDF)于2020-02-18）.
Pr(I)已在[PrB₄]⁻中觀察到，參見：Chen, Xin; Chen, Teng-Teng; Li, Wang-Lu; Lu, Jun-Bo; Zhao, Li-Juan; Jian, Tian; Hu, Han-Shi; Wang, Lai-Sheng; Li, Jun. Lanthanides with Unusually Low Oxidation States in the PrB₃^– and PrB₄^– Boride Clusters. Inorganic Chemistry. 2018-12-13, 58 (1): 411–418. PMID 30543295. S2CID 56148031. doi:10.1021/acs.inorgchem.8b02572.
Ir(IX)已在IrO+
4中觀察到，參見：Wang, Guanjun; Zhou, Mingfei; Goettel, James T.; Schrobilgen, Gary G.; Su, Jing; Li, Jun; Schlöder, Tobias; Riedel, Sebastian. Identification of an iridium-containing compound with a formal oxidation state of IX. Nature. 21 August 2014, 514 (7523): 475–477. Bibcode:2014Natur.514..475W. PMID 25341786. S2CID 4463905. doi:10.1038/nature13795.
Bi(IV)已被觀察到，參見：A. I. Aleksandrov, I. E. Makarov. Formation of Bi(II) and Bi(IV) in aqueous hydrochloric solutions of Bi(III). Bulletin of the Academy of Sciences of the USSR, Division of Chemical Science. 1987, 36 (2): 217–220. S2CID 94865394. doi:10.1007/BF00959349.
Rn(II)已在二氟化氡（RnF₂）中觀察到，參見：Stein, L. Ionic Radon Solution. Science. 1970, 168 (3929): 362–4. Bibcode:1970Sci...168..362S. PMID 17809133. S2CID 31959268. doi:10.1126/science.168.3929.362. and Kenneth S. Pitzer. Fluorides of radon and element 118. J. Chem. Soc., Chem. Commun. 1975, (18): 760b – 761 [2023-05-28]. doi:10.1039/C3975000760b. （原始内容存档于2021-12-08）.
Pu(VIII)已在PuO
4中觀察到，參見：Nikonov, M. V.; Kiselev, Yu. M.; Tananaev, I. G.; Myasoedov, B. F. Plutonium volatility in ozonization of alkaline solutions of Pu(VI) hydroxo complexes. Doklady Chemistry. March 2011, 437 (1): 69–71. S2CID 95951175. doi:10.1134/S0012500811030104. ，以及 Kiselev, Yu. M.; Nikonov, M. V.; Dolzhenko, V. D.; Ermilov, A. Yu.; Tananaev, I. G.; Myasoedov, B. F. On existence and properties of plutonium(VIII) derivatives. Radiochimica Acta. 17 January 2014, 102 (3): 227–237. S2CID 100915090. doi:10.1515/ract-2014-2146.
Kovács, Attila; Dau, Phuong D.; Marçalo, Joaquim; Gibson, John K. Pentavalent Curium, Berkelium, and Californium in Nitrate Complexes: Extending Actinide Chemistry and Oxidation States. Inorg. Chem. (American Chemical Society). 2018, 57 (15): 9453–9467. OSTI 1631597. PMID 30040397. S2CID 51717837. doi:10.1021/acs.inorgchem.8b01450.
Cm(VI)已在三氧化鋦（CmO₃）及二氧化鋦(2+)離子（CmO+
2）中觀察到，參見：Domanov, V. P.; Lobanov, Yu. V. Formation of volatile curium(VI) trioxide CmO₃. Radiochemistry. October 2011, 53 (5): 453–6. S2CID 98052484. doi:10.1134/S1066362211050018.
Cm(VIII)曾被報告可能存在於四氧化鋦（CmO₄）中，參閱：Domanov, V. P. Possibility of generation of octavalent curium in the gas phase in the form of volatile tetraoxide CmO₄. Radiochemistry. January 2013, 55 (1): 46–51. S2CID 98076989. doi:10.1134/S1066362213010098. 然而，後續的實驗顯示該物質似乎不存在：Zaitsevskii, Andréi; Schwarz, W H Eugen. Structures and stability of AnO4 isomers, An = Pu, Am, and Cm: a relativistic density functional study. Physical Chemistry Chemical Physics. April 2014, 2014 (16): 8997–9001. Bibcode:2014PCCP...16.8997Z. PMID 24695756. doi:10.1039/c4cp00235k.
Sg(VI)已在氫氧化氧𨭎（SgO₂(OH)₂）中觀察到，參見：Huebener, S.; Taut, S.; Vahle, A.; Dressler, R.; Eichler, B.; Gäggeler, H. W.; Jost, D.T.; Piguet, D.; et al. Physico-chemical characterization of seaborgium as oxide hydroxide (PDF). Radiochim. Acta. 2001, 89 (11–12_2001): 737–741. S2CID 98583998. doi:10.1524/ract.2001.89.11-12.737. （原始内容 (PDF)存档于2014-10-25）.
Sg(0)已在六羰基𨭎（Sg(CO)₆）中觀察到，參見：Even, J.; Yakushev, A.; Dullmann, C. E.; Haba, H.; Asai, M.; Sato, T. K.; Brand, H.; Di Nitto, A.; Eichler, R.; Fan, F. L.; Hartmann, W.; Huang, M.; Jager, E.; Kaji, D.; Kanaya, J.; Kaneya, Y.; Khuyagbaatar, J.; Kindler, B.; Kratz, J. V.; Krier, J.; Kudou, Y.; Kurz, N.; Lommel, B.; Miyashita, S.; Morimoto, K.; Morita, K.; Murakami, M.; Nagame, Y.; Nitsche, H.; et al. Synthesis and detection of a seaborgium carbonyl complex. Science. 2014, 345 (6203): 1491–3. Bibcode:2014Sci...345.1491E. PMID 25237098. S2CID 206558746. doi:10.1126/science.1255720.

pdfs.semanticscholar.org

Sb(0)已被觀察到，參見：Anastas Sidiropoulos. Studies of N-heterocyclic Carbene (NHC) Complexes of the Main Group Elements (PDF). : 39 [2023-05-28]. S2CID 132399530. doi:10.4225/03/5B0F4BDF98F60. （原始内容存档 (PDF)于2020-02-18）.

uni-freiburg.de

ruby.chemie.uni-freiburg.de

p區金屬（Al、Ga、In、Sn、Tl、Pb、Bi、Po）和類金屬（Si、Ge、As、Sb、Te、At）的負氧化態可能存在於津特耳相中，參見：Riedel, Erwin (编). Moderne Anorganische Chemie. 2007: 259 （德语） , and Vorlesung Intermetallische Phasen § 6.2 Binäre Zintl-Phasen. [2023-05-28]. （原始内容存档于2020-11-06）（德语）.

uni-kassel.de

Ga(−2)、Ga(−4)及Ga(−5)已分別在MgGa、Mg₂Ga和Mg₅Ga₂等鎂鎵化物中觀察到，參見：Patrick Hofmann. Colture. Ein Programm zur interaktiven Visualisierung von Festkörperstrukturen sowie Synthese, Struktur und Eigenschaften von binären und ternären Alkali- und Erdalkalimetallgalliden (PDF). : 72 [2023-05-28]. （原始内容存档 (PDF)于2021-02-03）（德语）.

unt.edu

digital.library.unt.edu

Es(IV)已知存在於氟化鑀(IV)（EsF₄）中，參見：Kleinschmidt, P. Thermochemistry of the actinides. Journal of Alloys and Compounds. 1994,. 213–214: 169–172 [2023-05-28]. doi:10.1016/0925-8388(94)90898-2. （原始内容存档于2020-03-16）.

uwaterloo.ca

bernath.uwaterloo.ca

Be(I)已在一氫化鈹（英语：Beryllium monohydride）（BeH）中觀察到，參見：Shayesteh, A.; Tereszchuk, K.; Bernath, P. F.; Colin, R. Infrared Emission Spectra of BeH and BeD (PDF). J. Chem. Phys. 2003, 118 (3): 1158 [2007-12-10]. Bibcode:2003JChPh.118.1158S. doi:10.1063/1.1528606. （原始内容 (PDF)存档于2007-12-02）. and in [(CAAC)₂Be]^+• [CAAC = cyclic (alkyl)(amino)carbene], see Wang, Guocang; Walley, Jacob E.; Dickie, Diane E.; Pan, Sudip; Frenking, Gernot; Gilliard Jr., Robert G. A Stable, Crystalline Beryllium Radical Cation. J. Am. Chem. Soc. 2020, 142 (10): 4560–4 [2020-11-17]. PMID 32088963. S2CID 211262005. doi:10.1021/jacs.9b13777. （原始内容存档于2022-09-24）.
Sr(I)已在SrF中觀察到，參見：P. Colarusso; Guo, B.; Zhang, K.-Q.; Bernath, P.F.; et al. High-Resolution Infrared Emission Spectrum of Strontium Monofluoride (PDF). Journal of Molecular Spectroscopy. 1996, 175 (1): 158–171. Bibcode:1996JMoSp.175..158C. doi:10.1006/jmsp.1996.0019. （原始内容 (PDF)存档于2012-03-08）.
Ba(I)已在一氟化鋇（BaF）中觀察到，參見：P. Colarusso; Guo, B.; Zhang, K.-Q.; Bernath, P.F.; et al. High-Resolution Fourier Transform Infrared Emission Spectrum of Barium Monofluoride (PDF). Journal of Molecular Spectroscopy. 1995, 170 (1): 59. Bibcode:1996JMoSp.175..158C. doi:10.1006/jmsp.1996.0019. （原始内容 (PDF)存档于2005-03-10）.

web.archive.org

Li(0)原子已在多種氯化鋰小團簇中觀察到，參見：Milovanović, Milan; Veličković, Suzana; Veljkovićb, Filip; Jerosimić, Stanka. Structure and stability of small lithium-chloride Li_nCl_m^(0,1+) (n ≥ m, n = 1–6, m = 1–3) clusters. Physical Chemistry Chemical Physics. October 30, 2017, (45) [2023-05-28]. doi:10.1039/C7CP04181K. （原始内容存档于2022-09-22）.
Be(0)已被觀察到，參見：Beryllium(0) Complex Found. Chemistry Europe（英语：Chemistry Europe）. 13 June 2016 [2023-05-28]. （原始内容存档于2020-10-28）.
Be(I)已在一氫化鈹（英语：Beryllium monohydride）（BeH）中觀察到，參見：Shayesteh, A.; Tereszchuk, K.; Bernath, P. F.; Colin, R. Infrared Emission Spectra of BeH and BeD (PDF). J. Chem. Phys. 2003, 118 (3): 1158 [2007-12-10]. Bibcode:2003JChPh.118.1158S. doi:10.1063/1.1528606. （原始内容 (PDF)存档于2007-12-02）. and in [(CAAC)₂Be]^+• [CAAC = cyclic (alkyl)(amino)carbene], see Wang, Guocang; Walley, Jacob E.; Dickie, Diane E.; Pan, Sudip; Frenking, Gernot; Gilliard Jr., Robert G. A Stable, Crystalline Beryllium Radical Cation. J. Am. Chem. Soc. 2020, 142 (10): 4560–4 [2020-11-17]. PMID 32088963. S2CID 211262005. doi:10.1021/jacs.9b13777. （原始内容存档于2022-09-24）.
B(−5)已在Al₃BC中觀察到，參見：Schroeder, Melanie. Eigenschaften von borreichen Boriden und Scandium-Aluminium-Oxid-Carbiden. : 139 [2023-05-28]. （原始内容存档于2020-08-06）（德语）.
B(−1)已在二硼化鎂（MgB₂）中觀察到，參見：Keeler, James; Wothers, Peter. Chemical Structure and Reactivity: An Integrated Approach. Oxford University Press. 2014 [2023-05-28]. ISBN 9780199604135. （原始内容存档于2022-09-22）.
已知含有氦原子的SF₆⁺團簇中有氟(0)原子作為配基，參見：Albertini, Simon; Bergmeister, Stefan; Laimer, Felix; Martini, Paul; Gruber, Elisabeth; Zappa, Fabio; Ončák, Milan; Scheier, Paul; Echt, Olof. SF 6 + : Stabilizing Transient Ions in Helium Nanodroplets. The Journal of Physical Chemistry Letters. 2021-04-22, 12 (17): 4112–4117 [2023-05-28]. ISSN 1948-7185. PMC 8154854 . PMID 33886323. doi:10.1021/acs.jpclett.1c01024 . （原始内容存档于2022-09-24）（英语）.
p區金屬（Al、Ga、In、Sn、Tl、Pb、Bi、Po）和類金屬（Si、Ge、As、Sb、Te、At）的負氧化態可能存在於津特耳相中，參見：Riedel, Erwin (编). Moderne Anorganische Chemie. 2007: 259 （德语） , and Vorlesung Intermetallische Phasen § 6.2 Binäre Zintl-Phasen. [2023-05-28]. （原始内容存档于2020-11-06）（德语）.
New Type of Zero-Valent Tin Compound. Chemistry Europe（英语：Chemistry Europe）. 27 August 2016 [2023-05-28]. （原始内容存档于2021-01-26）.
Ti(−2)、V(−3)、Cr(−4)、Co(−3)、Zr(−2)、Nb(−3)、Mo(−4)、Ru(−2)、Rh( −3)、Hf(−2)、Ta(−3)和W(−4)存在於陰離子二元金屬羰基錯合物中，參見：[1] （页面存档备份，存于互联网档案馆）, p. 4 (in German); [2], pp. 97–100; [3], p. 239
Cu(0)已在Cu(tris[2-(diisopropylphosphino)-phenyl]borane)中觀察到，參見：Moret, Marc-Etienne; Zhang, Limei; Peters, Jonas C. A Polar Copper–Boron One-Electron σ-Bond. J. Am. Chem. Soc. 2013, 135 (10): 3792–3795 [2023-05-28]. PMID 23418750. doi:10.1021/ja4006578. （原始内容存档于2022-10-07）.
Ga(−2)、Ga(−4)及Ga(−5)已分別在MgGa、Mg₂Ga和Mg₅Ga₂等鎂鎵化物中觀察到，參見：Patrick Hofmann. Colture. Ein Programm zur interaktiven Visualisierung von Festkörperstrukturen sowie Synthese, Struktur und Eigenschaften von binären und ternären Alkali- und Erdalkalimetallgalliden (PDF). : 72 [2023-05-28]. （原始内容存档 (PDF)于2021-02-03）（德语）.
Ga(−3)已在LaGa中觀察到，參見：Dürr, Ines; Bauer, Britta; Röhr, Caroline. Lanthan-Triel/Tetrel-ide La(Al,Ga)_x(Si,Ge)_1-x. Experimentelle und theoretische Studien zur Stabilität intermetallischer 1:1-Phasen (PDF). Z. Naturforsch. 2011, 66b: 1107–1121 [2023-05-28]. （原始内容存档 (PDF)于2020-08-04）（德语）.
Se(I)已在二氯化二硒（Se₂Cl₂）中觀察到，參見：Selenium: Selenium(I) chloride compound data. WebElements.com. [2007-12-10]. （原始内容存档于2008-05-11）.
Se(V)已在SeO−
3及HSeO2−
4中觀察到，參見：Kläning, Ulrik K.; Sehested, K. Selenium(V). A pulse radiolysis study. Inorganic Chemistry. 1986, 90 (21): 5460–4 [2023-05-28]. doi:10.1021/j100412a112. （原始内容存档于2019-03-22）.
Br(II)已知存在於一氧化溴自由基中，參見：[4] （页面存档备份，存于互联网档案馆）
Sr(I)已在SrF中觀察到，參見：P. Colarusso; Guo, B.; Zhang, K.-Q.; Bernath, P.F.; et al. High-Resolution Infrared Emission Spectrum of Strontium Monofluoride (PDF). Journal of Molecular Spectroscopy. 1996, 175 (1): 158–171. Bibcode:1996JMoSp.175..158C. doi:10.1006/jmsp.1996.0019. （原始内容 (PDF)存档于2012-03-08）.
Y(I)已在YBr中觀察到，參見：Yttrium: yttrium(I) bromide compound data. OpenMOPAC.net. [2007-12-10]. （原始内容存档于2011-07-23）.
Pd(III)已被觀察到，參見：Powers, D. C.; Ritter, T. Palladium(III) in Synthesis and Catalysis (PDF). Topics in Organometallic Chemistry 35. 2011: 129–156. Bibcode:2011hoso.book..129P. ISBN 978-3-642-17428-5. PMC 3066514 . PMID 21461129. doi:10.1007/978-3-642-17429-2_6. （原始内容 (PDF)存档于June 12, 2013）. |journal=被忽略 (帮助)
不穩定的In(0)羰基錯合物和團簇已被檢測到，參見：[6] （页面存档备份，存于互联网档案馆）, p. 6.
Sn(−3)已在[Sn₂]⁶⁻中觀察到，例如在(Ba₂)⁴⁺(Mg₄)⁸⁺Sn⁴⁻(Sn₂)⁶⁻Sn²⁻中（其中有正方形層狀(Sn²⁻)_n），參見：Papoian, Garegin A.; Hoffmann, Roald. Hypervalent Bonding in One, Two, and Three Dimensions: Extending the Zintl–Klemm Concept to Nonclassical Electron-Rich Networks. Angew. Chem. Int. Ed. 2000, 2000 (39): 2408–2448 [2015-02-23]. doi:10.1002/1521-3773(20000717)39:14<2408::aid-anie2408>3.0.co;2-u. （原始内容存档于2018-10-26）.
Sb(0)已被觀察到，參見：Anastas Sidiropoulos. Studies of N-heterocyclic Carbene (NHC) Complexes of the Main Group Elements (PDF). : 39 [2023-05-28]. S2CID 132399530. doi:10.4225/03/5B0F4BDF98F60. （原始内容存档 (PDF)于2020-02-18）.
Te(I)已在一碘化碲（TeI）中觀察到，參見：Tellurium: tellurium iodide. WebElements.com. [2015-02-23]. （原始内容存档于2020-07-24）.
Te(III)已在[Te(N(SiMe₃)₂)₂]⁺中觀察到，參見：Heinze, Thorsten; Roesky, Herbert W.; Pauer, Frank; Stalke, Dietmar; Sheldrick, George M. Synthesis and Structure of the First Tellurium(III) Radical Cation. Angewandte Chemie International Edition. 1991, 30 (12): 1678 [2015-02-23]. doi:10.1002/anie.199116771. （原始内容存档于2018-09-19）.
Te(V)曾被Greenwood and Earnshaw提及，但他們沒有舉出任何Te(V)化合物的例子。而長久以來被認為是十氟化二碲（英语：Ditellurium decafluoride）（Te₂F₁₀）的物質實際上是雙(五氟碲基)氧化物：F₅TeOTeF₅，參見：Watkins, P. M. Ditellurium decafluoride - A Continuing Myth. Journal of Chemical Education. 1974, 51 (9): 520–521. Bibcode:1974JChEd..51..520W. doi:10.1021/ed051p520. 不過，Te(V)已在HTeO−
、TeO−
、HTeO−
2及TeO−
3中觀察到，參見：Kläning, Ulrik K.; Sehested, K. Tellurium(V). A Pulse Radiolysis Study. The Journal of Physical Chemistry A. 2001, 105 (27): 6637–45 [2023-05-28]. Bibcode:2001JPCA..105.6637K. doi:10.1021/jp010577i. （原始内容存档于2019-03-22）.
Ba(I)已在一氟化鋇（BaF）中觀察到，參見：P. Colarusso; Guo, B.; Zhang, K.-Q.; Bernath, P.F.; et al. High-Resolution Fourier Transform Infrared Emission Spectrum of Barium Monofluoride (PDF). Journal of Molecular Spectroscopy. 1995, 170 (1): 59. Bibcode:1996JMoSp.175..158C. doi:10.1006/jmsp.1996.0019. （原始内容 (PDF)存档于2005-03-10）.
La(I)、Pr(I)、Tb(I)、Tm(I)及Yb(I)已在MB₈⁻簇合物中觀察到，參見：Li, Wan-Lu; Chen, Teng-Teng; Chen, Wei-Jia; Li, Jun; Wang, Lai-Sheng. Monovalent lanthanide(I) in borozene complexes. Nature Communications. 2021, 12: 6467 [2023-05-28]. doi:10.1038/s41467-021-26785-9. （原始内容存档于2022-09-26）.
所有鑭系元素（鑭至鎦）的+2氧化態均已在其二鹵化物和鹼土金屬二鹵化物形成的稀固溶體中（參閱：Holleman, Arnold Frederik; Wiberg, Egon, Wiberg, Nils , 编, Inorganic Chemistry, 由Eagleson, Mary; Brewer, William翻译, San Diego/Berlin: Academic Press/De Gruyter, 2001, ISBN 0-12-352651-5 ，鑭、釓、鎦除外）以及其有機金屬分子錯合物中（鉕除外）觀察到，參見：Lanthanides Topple Assumptions （页面存档备份，存于互联网档案馆） and Meyer, G. All the Lanthanides Do It and Even Uranium Does Oxidation State +2. Angewandte Chemie International Edition. 2014, 53 (14): 3550–51. PMID 24616202. doi:10.1002/anie.201311325. 。此外，雖然所有鑭系元素皆形成二氫化物（LnH₂）、二碳化物（LnC₂）、一硫化物（LnS）、一硒化物（LnSe）和一碲化物（LnTe），但對於大多數鑭系元素，這些化合物中的鑭系離子實為+3態，伴隨著離域至導帶的電子，例如：Ln³⁺(H⁻)₂(e⁻)。
SmB₆^-團簇陰離子已被報告，其中含有罕見的+1態釤，參見：Paul, J. Robinson; Xinxing, Zhang; Tyrel, McQueen; Kit, H. Bowen; Anastassia, N. Alexandrova. SmB₆^– Cluster Anion: Covalency Involving f Orbitals. J. Phys. Chem. A 2017, 121, 8, 1849–1854. 2017, 121 (8): 1849–1854 [2023-05-28]. （原始内容存档于2022-09-25）. .
Hf(I)已在一溴化鉿（HfBr）中觀察到，參見：Marek, G.S.; Troyanov, S.I.; Tsirel'nikov, V.I. Кристаллическое строение и термодинамические характеристики монобромидов циркония и гафния / Crystal structure and thermodynamic characteristics of monobromides of zirconium and hafnium. Журнал неорганической химии / Russian Journal of Inorganic Chemistry. 1979, 24 (4): 890–893 [2023-05-28]. （原始内容存档于2020-08-01）（俄语）.
Ir(VII)已在[(η²-O₂)IrO₂]⁺中觀察到，參見：C&EN: Iridium dressed to the nines （页面存档备份，存于互联网档案馆）.
Hg(IV)曾被報告發現存在於四氟化汞（HgF₄）中，參見：Xuefang Wang; Lester Andrews; Sebastian Riedel; Martin Kaupp. Mercury Is a Transition Metal: The First Experimental Evidence for HgF₄. Angew. Chem. Int. Ed. 2007, 46 (44): 8371–8375. PMID 17899620. doi:10.1002/anie.200703710. 但之後的實驗無法證實該發現，參閱：Is mercury a transition metal? 互联网档案馆的存檔，存档日期2016-10-12.
含Pb(0)的羰基錯合物已在鉛原子和一氧化碳間的反應中觀察到，參見：Ling, Jiang; Qiang, Xu. Observation of the lead carbonyls Pb_nCO (n=1–4): Reactions of lead atoms and small clusters with carbon monoxide in solid argon. The Journal of Chemical Physics. 122 (3): 034505. 2005, 122 (3): 34505 [2023-05-28]. Bibcode:2005JChPh.122c4505J. ISSN 0021-9606. PMID 15740207. doi:10.1063/1.1834915. （原始内容存档于2022-11-08）.
Bi(−2)及Bi(−1)存在於津特耳相中，例如(Ca²⁺)₂₂[Bi₄]⁴⁻([Bi₂]⁴⁻)₄[Bi³⁻]₈；參閱：Ponou, Siméon. Germanides, Germanide-Tungstate Double Salts and Substitution Effects in Zintl Phases. Technische Universität München. Lehrstuhl für Anorganische Chemie mit Schwerpunkt Neue Materialien. 2006: 68 [2023-05-28]. （原始内容存档于2015-02-21）.
Bi(0)已知存在於二鉍烯的N-雜環碳烯錯合物中，參見：Deka, Rajesh; Orthaber, Andreas. Carbene chemistry of arsenic, antimony, and bismuth: origin, evolution and future prospects. Royal Society of Chemistry. May 6, 2022, (51): 8540 [2023-05-28]. doi:10.1039/d2dt00755j. （原始内容存档于2022-09-22）.
Rn(II)已在二氟化氡（RnF₂）中觀察到，參見：Stein, L. Ionic Radon Solution. Science. 1970, 168 (3929): 362–4. Bibcode:1970Sci...168..362S. PMID 17809133. S2CID 31959268. doi:10.1126/science.168.3929.362. and Kenneth S. Pitzer. Fluorides of radon and element 118. J. Chem. Soc., Chem. Commun. 1975, (18): 760b – 761 [2023-05-28]. doi:10.1039/C3975000760b. （原始内容存档于2021-12-08）.
Th(I)已知存在於溴化釷(I)（ThBr）中，參見：Wickleder, Mathias S.; Fourest, Blandine; Dorhout, Peter K. Thorium. Morss, Lester R.; Edelstein, Norman M.; Fuger, Jean (编). The Chemistry of the Actinide and Transactinide Elements (PDF) 3 3rd. Dordrecht, the Netherlands: Springer. 2006: 52–160. ISBN 978-1-4020-3555-5. doi:10.1007/1-4020-3598-5_3. （原始内容 (PDF)存档于2016-03-07）.
Am(VII)已在AmO−
5中觀察到，參見：Americium （页面存档备份，存于互联网档案馆）, Das Periodensystem der Elemente für den Schulgebrauch (The periodic table of elements for schools) chemie-master.de (in German), Retrieved 28 November 2010 and Greenwood, N. N.; Earnshaw, A. Chemistry of the Elements 2nd. Oxford:Butterworth-Heinemann. 1997: 1265. ISBN 0-7506-3365-4.
Cm(V)、Bk(V)及Cf(V)已在BkO₂⁺、CfO₂⁺、CmO₂(NO₃)₂⁻、BkO₂(NO₃)₂⁻及CfO₂(NO₃)₂⁻中觀察到，參見：Dau, Phuong Diem; Vasiliu, Monica; Peterson, Kirk A; Dixon, David A; Gibsoon, John K. Remarkably High Stability of Late Actinide Dioxide Cations: Extending Chemistry to Pentavalent Berkelium and Californium. Chemistry - A European Journal. October 2017, 23 (68): 17369–17378 [2023-05-28]. PMID 29024093. doi:10.1002/chem.201704193. （原始内容存档于2023-03-26）.
Es(IV)已知存在於氟化鑀(IV)（EsF₄）中，參見：Kleinschmidt, P. Thermochemistry of the actinides. Journal of Alloys and Compounds. 1994,. 213–214: 169–172 [2023-05-28]. doi:10.1016/0925-8388(94)90898-2. （原始内容存档于2020-03-16）.
Db(V)已在五氯化𨧀（DbCl₅）中觀察到，參見：H. W. Gäggeler. Gas Phase Chemistry of Superheavy Elements (PDF). Paul Scherrer Institute: 26–28. 2007. （原始内容 (PDF)存档于2012-02-20）.
Sg(VI)已在氫氧化氧𨭎（SgO₂(OH)₂）中觀察到，參見：Huebener, S.; Taut, S.; Vahle, A.; Dressler, R.; Eichler, B.; Gäggeler, H. W.; Jost, D.T.; Piguet, D.; et al. Physico-chemical characterization of seaborgium as oxide hydroxide (PDF). Radiochim. Acta. 2001, 89 (11–12_2001): 737–741. S2CID 98583998. doi:10.1524/ract.2001.89.11-12.737. （原始内容 (PDF)存档于2014-10-25）.
Bh(VII)已在氯氧化𨨏（BhO₃Cl）中觀察到，參見："Gas chemical investigation of bohrium (Bh, element 107)" 互联网档案馆的存檔，存档日期2008-02-28., Eichler et al., GSI Annual Report 2000. Retrieved on 2008-02-29
Hs(VIII)已在四氧化𨭆（HsO₄）中觀察到，參見：Chemistry of Hassium (PDF). Gesellschaft für Schwerionenforschung mbH. 2002 [2007-01-31]. （原始内容存档 (PDF)于2012-03-11）.
Cn(II)已在硒化鎶（CnSe）中觀察到，參見：Annual Report 2015: Laboratory of Radiochemistry and Environmental Chemistry (PDF). Paul Scherrer Institute: 3. 2015 [2023-05-28]. （原始内容存档 (PDF)于2016-12-20）.
Langmuir, Irving. THE ARRANGEMENT OF ELECTRONS IN ATOMS AND MOLECULES.. Journal of the American Chemical Society. 1919-06, 41 (6): 868–934 [2022-03-25]. ISSN 0002-7863. doi:10.1021/ja02227a002. （原始内容存档于2020-05-09）（英语）.

webelements.com

Se(I)已在二氯化二硒（Se₂Cl₂）中觀察到，參見：Selenium: Selenium(I) chloride compound data. WebElements.com. [2007-12-10]. （原始内容存档于2008-05-11）.
Te(I)已在一碘化碲（TeI）中觀察到，參見：Tellurium: tellurium iodide. WebElements.com. [2015-02-23]. （原始内容存档于2020-07-24）.

wikipedia.org

en.wikipedia.org

Be(0)已被觀察到，參見：Beryllium(0) Complex Found. Chemistry Europe（英语：Chemistry Europe）. 13 June 2016 [2023-05-28]. （原始内容存档于2020-10-28）.
Be(I)已在一氫化鈹（英语：Beryllium monohydride）（BeH）中觀察到，參見：Shayesteh, A.; Tereszchuk, K.; Bernath, P. F.; Colin, R. Infrared Emission Spectra of BeH and BeD (PDF). J. Chem. Phys. 2003, 118 (3): 1158 [2007-12-10]. Bibcode:2003JChPh.118.1158S. doi:10.1063/1.1528606. （原始内容 (PDF)存档于2007-12-02）. and in [(CAAC)₂Be]^+• [CAAC = cyclic (alkyl)(amino)carbene], see Wang, Guocang; Walley, Jacob E.; Dickie, Diane E.; Pan, Sudip; Frenking, Gernot; Gilliard Jr., Robert G. A Stable, Crystalline Beryllium Radical Cation. J. Am. Chem. Soc. 2020, 142 (10): 4560–4 [2020-11-17]. PMID 32088963. S2CID 211262005. doi:10.1021/jacs.9b13777. （原始内容存档于2022-09-24）.
B(0)已在雙硼炔（英语：diboryne）中觀察到，參見：Braunschweig, H.; Dewhurst, R. D.; Hammond, K.; Mies, J.; Radacki, K.; Vargas, A. Ambient-Temperature Isolation of a Compound with a Boron-Boron Triple Bond. Science. 2012, 336 (6087): 1420–2. Bibcode:2012Sci...336.1420B. PMID 22700924. S2CID 206540959. doi:10.1126/science.1221138.
New Type of Zero-Valent Tin Compound. Chemistry Europe（英语：Chemistry Europe）. 27 August 2016 [2023-05-28]. （原始内容存档于2021-01-26）.
已在以氖作為基質的隔離（英语：Matrix isolation）下觀察到鈣、鍶、鋇的八羰基配合物，但尚不清楚這些是否為其0價態配合物，因為計算結果否定了配合物中金屬原子和配體形成共價鍵或離子鍵與否，參見：Wu, X.; Zhao, L.; Jin, J.; Pan, S.; Li, W.; Jin, X.; Wang, G.; Zhou, M.; Frenking, G. Observation of alkaline earth complexes M(CO)8 (M = Ca, Sr, or Ba) that mimic transition metals. Science. 2018, 361 (6405): 912–916. Bibcode:2018Sci...361..912W. PMID 30166489. S2CID 52131470. doi:10.1126/science.aau0839
Fe(−4)、Ru(−4)和Os(−4)已在含有八面體配合物[MIn_6−xSn_x]的富金屬化合物中觀察到；Pt(−3)（以二聚體陰離子[Pt–Pt]⁶⁻的形式）、Cu(−2)、Zn(−2)、Ag(−2)、Cd(−2)、Au(−2)和Hg(−2)（以二聚體和單體陰離子之形式；Zn、Cd、Hg的二聚體離子最初被報告為[T–T]²⁻的形式、但後來的研究顯示所有這些元素的二聚體陰離子皆為[T–T]⁴⁻形式）已在下列化合物中觀察到：La₂Pt₂In、La₂Cu₂In、Ca₅Au₃、Ca₅Ag₃、Ca₅Hg₃、Sr₅Cd₃、Ca₅Zn₃（結構為(AE²⁺)₅(T–T)⁴⁻T^{2 −}⋅4e⁻）、Yb₃Ag₂、Ca₅Au₄和Ca₃Hg₂；Au(-3)已在ScAuSn及其他18電子的半赫斯勒化合物（英语：Heusler compound）中觀察到。參見：Changhoon Lee; Myung-Hwan Whangbo. Late transition metal anions acting as p-metal elements. Solid State Sciences. 2008, 10 (4): 444–449. Bibcode:2008SSSci..10..444K. doi:10.1016/j.solidstatesciences.2007.12.001. and Changhoon Lee; Myung-Hwan Whangbo; Jürgen Köhler. Analysis of Electronic Structures and Chemical Bonding of Metal-rich Compounds. 2. Presence of Dimer (T–T)^4– and Isolated T^2– Anions in the Polar Intermetallic Cr₅B₃-Type Compounds AE₅T₃ (AE = Ca, Sr; T = Au, Ag, Hg, Cd, Zn). Zeitschrift für Anorganische und Allgemeine Chemie. 2010, 636 (1): 36–40. doi:10.1002/zaac.200900421.
Zn(I)已在二(五甲基環戊二烯)基鋅（英语：decamethyldizincocene）（Zn₂(η⁵–C₅Me₅)₂）中觀察到，參見：Resa, I.; Carmona, E.; Gutierrez-Puebla, E.; Monge, A. Decamethyldizincocene, a Stable Compound of Zn(I) with a Zn-Zn Bond. Science. 2004, 305 (5687): 1136–8. Bibcode:2004Sci...305.1136R. PMID 15326350. S2CID 38990338. doi:10.1126/science.1101356.
Ag(0)已在低溫基質隔離（英语：Matrix isolation）條件下的羰基絡合物中觀察到，參見McIntosh, D.; Ozin, G. A. Synthesis using metal vapors. Silver carbonyls. Matrix infrared, ultraviolet-visible, and electron spin resonance spectra, structures, and bonding of silver tricarbonyl, silver dicarbonyl, silver monocarbonyl, and disilver hexacarbonyl. J. Am. Chem. Soc. 1976, 98 (11): 3167–75. doi:10.1021/ja00427a018.
Te(V)曾被Greenwood and Earnshaw提及，但他們沒有舉出任何Te(V)化合物的例子。而長久以來被認為是十氟化二碲（英语：Ditellurium decafluoride）（Te₂F₁₀）的物質實際上是雙(五氟碲基)氧化物：F₅TeOTeF₅，參見：Watkins, P. M. Ditellurium decafluoride - A Continuing Myth. Journal of Chemical Education. 1974, 51 (9): 520–521. Bibcode:1974JChEd..51..520W. doi:10.1021/ed051p520. 不過，Te(V)已在HTeO−
、TeO−
、HTeO−
2及TeO−
3中觀察到，參見：Kläning, Ulrik K.; Sehested, K. Tellurium(V). A Pulse Radiolysis Study. The Journal of Physical Chemistry A. 2001, 105 (27): 6637–45 [2023-05-28]. Bibcode:2001JPCA..105.6637K. doi:10.1021/jp010577i. （原始内容存档于2019-03-22）.

worldcat.org

已知含有氦原子的SF₆⁺團簇中有氟(0)原子作為配基，參見：Albertini, Simon; Bergmeister, Stefan; Laimer, Felix; Martini, Paul; Gruber, Elisabeth; Zappa, Fabio; Ončák, Milan; Scheier, Paul; Echt, Olof. SF 6 + : Stabilizing Transient Ions in Helium Nanodroplets. The Journal of Physical Chemistry Letters. 2021-04-22, 12 (17): 4112–4117 [2023-05-28]. ISSN 1948-7185. PMC 8154854 . PMID 33886323. doi:10.1021/acs.jpclett.1c01024 . （原始内容存档于2022-09-24）（英语）.
已使用DFT在[ReOSe(2-pySe)₃]中識別出Se(0)原子，參見：Cargnelutti, Roberta; Lang, Ernesto S.; Piquini, Paulo; Abram, Ulrich. Synthesis and structure of [ReOSe(2-Se-py)3]: A rhenium(V) complex with selenium(0) as a ligand. Inorganic Chemistry Communications. 2014, 45: 48–50. ISSN 1387-7003. doi:10.1016/j.inoche.2014.04.003.
Pr(V)已在[PrO₂]⁺中觀察到，參見：Zhang, Qingnan; Hu, Shu-Xian; Qu, Hui; Su, Jing; Wang, Guanjun; Lu, Jun-Bo; Chen, Mohua; Zhou, Mingfei; Li, Jun. Pentavalent Lanthanide Compounds: Formation and Characterization of Praseodymium(V) Oxides. Angewandte Chemie International Edition. 2016-06-06, 55 (24): 6896–6900. ISSN 1521-3773. PMID 27100273. doi:10.1002/anie.201602196.
Hu, Shu-Xian; Jian, Jiwen; Su, Jing; Wu, Xuan; Li, Jun; Zhou, Mingfei. Pentavalent lanthanide nitride-oxides: NPrO and NPrO− complexes with N≡Pr triple bonds. Chemical Science. 2017, 8 (5): 4035–4043. ISSN 2041-6520. PMC 5434915 . PMID 28580119. doi:10.1039/C7SC00710H （英语）.
含Pb(0)的羰基錯合物已在鉛原子和一氧化碳間的反應中觀察到，參見：Ling, Jiang; Qiang, Xu. Observation of the lead carbonyls Pb_nCO (n=1–4): Reactions of lead atoms and small clusters with carbon monoxide in solid argon. The Journal of Chemical Physics. 122 (3): 034505. 2005, 122 (3): 34505 [2023-05-28]. Bibcode:2005JChPh.122c4505J. ISSN 0021-9606. PMID 15740207. doi:10.1063/1.1834915. （原始内容存档于2022-11-08）.
Th(-I)及U(-I)已在氣相中以八羰基陰離子的形式被檢測到，參見：Chaoxian, Chi; Sudip, Pan; Jiaye, Jin; Luyan, Meng; Mingbiao, Luo; Lili, Zhao; Mingfei, Zhou; Gernot, Frenking. Octacarbonyl Ion Complexes of Actinides [An(CO)₈]^+/− (An=Th, U) and the Role of f Orbitals in Metal–Ligand Bonding. Chemistry (Weinheim an der Bergstrasse, Germany). 25 (50): 11772–11784. 2019, 25 (50): 11772–11784. ISSN 0947-6539. PMC 6772027 . PMID 31276242. doi:10.1002/chem.201902625.
Th(-I)及U(-I)已在氣相中以八羰基陰離子的形式被檢測到，參見：Chaoxian, Chi; Sudip, Pan; Jiaye, Jin; Luyan, Meng; Mingbiao, Luo; Lili, Zhao; Mingfei, Zhou; Gernot, Frenking. Octacarbonyl Ion Complexes of Actinides [An(CO)₈]^+/− (An=Th, U) and the Role of f Orbitals in Metal–Ligand Bonding. Chemistry (Weinheim an der Bergstrasse, Germany). 25 (50): 11772–11784. 2019, 25 (50): 11772–11784. ISSN 0947-6539. PMC 6772027 . PMID 31276242. doi:10.1002/chem.201902625.
Langmuir, Irving. THE ARRANGEMENT OF ELECTRONS IN ATOMS AND MOLECULES.. Journal of the American Chemical Society. 1919-06, 41 (6): 868–934 [2022-03-25]. ISSN 0002-7863. doi:10.1021/ja02227a002. （原始内容存档于2020-05-09）（英语）.

znaturforsch.com

Ga(−3)已在LaGa中觀察到，參見：Dürr, Ines; Bauer, Britta; Röhr, Caroline. Lanthan-Triel/Tetrel-ide La(Al,Ga)_x(Si,Ge)_1-x. Experimentelle und theoretische Studien zur Stabilität intermetallischer 1:1-Phasen (PDF). Z. Naturforsch. 2011, 66b: 1107–1121 [2023-05-28]. （原始内容存档 (PDF)于2020-08-04）（德语）.