Oxidation state (English Wikipedia)

Analysis of information sources in references of the Wikipedia article "Oxidation state" in English language version.

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Br(II) is known to occur in bromine monoxide radical; see Kinetics of the bromine monoxide radical + bromine monoxide radical reaction
SmB₆⁻ cluster anion has been reported and contains Sm in rare oxidation state of +1; see Paul, J. Robinson; Xinxing, Zhang; Tyrel, McQueen; Kit, H. Bowen; Anastassia, N. Alexandrova (2017). "SmB₆^– Cluster Anion: Covalency Involving f Orbitals". J. Phys. Chem. A 2017,^? 121,^? 8,^? 1849–1854. 121 (8): 1849–1854. Bibcode:2017JPCA..121.1849R. doi:10.1021/acs.jpca.7b00247. PMID 28182423. S2CID 3723987..

cen.acs.org

All the lanthanides, except Pm, in the +2 oxidation state have been observed in organometallic molecular complexes, see Lanthanides Topple Assumptions and Meyer, G. (2014). "All the Lanthanides Do It and Even Uranium Does Oxidation State +2". Angewandte Chemie International Edition. 53 (14): 3550–51. doi:10.1002/anie.201311325. PMID 24616202.. Additionally, all the lanthanides (La–Lu) form dihydrides (LnH₂), dicarbides (LnC₂), monosulfides (LnS), monoselenides (LnSe), and monotellurides (LnTe), but for most elements these compounds have Ln³⁺ ions with electrons delocalized into conduction bands, e. g. Ln³⁺(H⁻)₂(e⁻).

acs.org

"Antoine Laurent Lavoisier The Chemical Revolution – Landmark – American Chemical Society". American Chemical Society. Archived from the original on 5 January 2021. Retrieved 14 July 2018.

aip.org

pubs.aip.org

Ma, Wen; Herbert, F. William; Senanayake, Sanjaya D.; Yildiz, Bilge (2015-03-09). "Non-equilibrium oxidation states of zirconium during early stages of metal oxidation". Applied Physics Letters. 106 (10). Bibcode:2015ApPhL.106j1603M. doi:10.1063/1.4914180. hdl:1721.1/104888. ISSN 0003-6951.

archive.org

Petrucci, R. H.; Harwood, W. S.; Herring, F. G. (2002). General Chemistry (8th ed.). Prentice-Hall. ISBN 978-0-13-033445-9.^{[ISBN missing]}
Whitten, K. W.; Galley, K. D.; Davis, R. E. (1992). General Chemistry (4th ed.). Saunders. p. 147. ISBN 978-0-03-075156-1.^{[ISBN missing]}

arxiv.org

Disodium helide, (Na⁺)₂He(e⁻)₂, has been synthesized at high pressure, see 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 (6 February 2017). "A stable compound of helium and sodium at high pressure". Nature Chemistry. 9 (5): 440–445. arXiv:1309.3827. Bibcode:2017NatCh...9..440D. doi:10.1038/nchem.2716. PMID 28430195. S2CID 20459726.

books.google.com

B(−1) has been observed in magnesium diboride (MgB₂), see Keeler, James; Wothers, Peter (2014). Chemical Structure and Reactivity: An Integrated Approach. Oxford University Press. ISBN 9780199604135.
In(−2) has been observed in Na₂In, see [1], p. 69.
Harding, Charlie; Johnson, David Arthur; Janes, Rob (2002). Elements of the p block. Great Britain: Royal Society of Chemistry. pp. 93–94. ISBN 0-85404-690-9.
Rn(II) and Rn(VI) are known in RnF₂ and RnO₃, respectively; see Sykes, A. G. (1998). "Recent Advances in Noble-Gas Chemistry". Advances in Inorganic Chemistry. Vol. 46. Academic Press. pp. 91–93. ISBN 978-0120236466. Retrieved 2012-11-02.
Kaldor, Uzi; Wilson, Stephen (2003). Theoretical Chemistry and Physics of Heavy and Superheavy Elements. Springer. p. 105. ISBN 978-1402013713. Retrieved 2008-01-18.

caltech.edu

authors.library.caltech.edu

Moret, Marc-Etienne; Zhang, Limei; Peters, Jonas C. (2013). "A Polar Copper–Boron One-Electron σ-Bond". J. Am. Chem. Soc. 135 (10): 3792–3795. Bibcode:2013JAChS.135.3792M. doi:10.1021/ja4006578. PMID 23418750.
Pauling, L. (1948). "The modern theory of valency". J. Chem. Soc. 1948: 1461–1467. doi:10.1039/JR9480001461. PMID 18893624. Archived from the original on 2021-12-07. Retrieved 2021-11-22.

chemistryviews.org

"New Type of Zero-Valent Tin Compound". Chemistry Europe. 27 August 2016.
"New Type of Zero-Valent Tin Compound". Chemistry Europe. 27 August 2016.
"New Type of Zero-Valent Tin Compound". Chemistry Europe. 27 August 2016.

d-nb.info

Schroeder, Melanie, Eigenschaften von borreichen Boriden und Scandium-Aluminium-Oxid-Carbiden (in German), p. 139, archived from the original on 2020-08-06, retrieved 2020-02-24
B(−5) has been observed in Al₃BC, see Schroeder, Melanie. "Eigenschaften von borreichen Boriden und Scandium-Aluminium-Oxid-Carbiden" (in German). p. 139.

degruyter.com

Brauer, G.; Haucke, W. (1936-06-01). "Kristallstruktur der intermetallischen Phasen MgAu und MgHg". Zeitschrift für Physikalische Chemie. 33B (1): 304–310. doi:10.1515/zpch-1936-3327. ISSN 2196-7156. MgHg then lends itself to an oxidation state of +2 for Mg and -2 for Hg because it consists entirely of these polar bonds with no evidence of electron unpairing. (translated)

doi.org

Wang, G.; Zhou, M.; Goettel, G. T.; Schrobilgen, G. J.; Su, J.; Li, J.; Schlöder, T.; Riedel, S. (2014). "Identification of an iridium-containing compound with a formal oxidation state of IX". Nature. 514 (7523): 475–477. Bibcode:2014Natur.514..475W. doi:10.1038/nature13795. PMID 25341786. S2CID 4463905.
Yu, Haoyu S.; Truhlar, Donald G. (2016). "Oxidation State 10 Exists". Angewandte Chemie International Edition. 55 (31): 9004–9006. doi:10.1002/anie.201604670. PMID 27273799.
Karen, P.; McArdle, P.; Takats, J. (2016). "Comprehensive definition of oxidation state (IUPAC Recommendations 2016)". Pure Appl. Chem. 88 (8): 831–839. doi:10.1515/pac-2015-1204. hdl:10852/59520. S2CID 99403810.
Karen, P.; McArdle, P.; Takats, J. (2014). "Toward a comprehensive definition of oxidation state (IUPAC Technical Report)". Pure Appl. Chem. 86 (6): 1017–1081. doi:10.1515/pac-2013-0505.
IUPAC, Compendium of Chemical Terminology, 2nd ed. (the "Gold Book") (1997). Online corrected version: (2006–) "Oxidation state". doi:10.1351/goldbook.O04365
IUPAC, Compendium of Chemical Terminology, 2nd ed. (the "Gold Book") (1997). Online corrected version: (2006–) "Oxidation number". doi:10.1351/goldbook.O04363
Karen, Pavel (2015). "Oxidation State, A Long-Standing Issue!". Angewandte Chemie International Edition. 54 (16): 4716–4726. doi:10.1002/anie.201407561. PMC 4506524. PMID 25757151.
Hooydonk, G. Van (1974-05-01). "O n an Ionic Approximation to Chemical Bonding". Zeitschrift für Naturforschung A. 29 (5): 763–767. Bibcode:1974ZNatA..29..763H. doi:10.1515/zna-1974-0517. ISSN 1865-7109.
"Oxidation state". The IUPAC Compendium of Chemical Terminology: The Gold Book. 2009. doi:10.1351/goldbook.O04365. ISBN 978-0-9678550-9-7.
Muir, K. W.; Ibers, J. A. (1969). "The structure of chlorocarbonyl(sulfur dioxide)bis(triphenylphosphine)rhodium, (RhCl(CO)(SO2)(P(C6H5)3 2)". Inorg. Chem. 8 (9): 1921–1928. doi:10.1021/ic50079a024.
Martinie, R. J.; Bultema, J. J.; Wal, M. N. V.; Burkhart, B. J.; Griend, D. A. V.; DeCock, R. L. (2011). "Bond order and chemical properties of BF, CO, and N₂". J. Chem. Educ. 88 (8): 1094–1097. Bibcode:2011JChEd..88.1094M. doi:10.1021/ed100758t.
Senn, M. S.; Wright, J. P.; Attfield, J. P. (2012). "Charge order and three-site distortions in the Verwey structure of magnetite" (PDF). Nature. 481 (7380): 173–6. Bibcode:2012Natur.481..173S. doi:10.1038/nature10704. hdl:20.500.11820/1b3bb558-52d5-419f-9944-ab917dc95f5e. PMID 22190035. S2CID 4425300. Archived (PDF) from the original on 2022-10-09.
Disodium helide, (Na⁺)₂He(e⁻)₂, has been synthesized at high pressure, see 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 (6 February 2017). "A stable compound of helium and sodium at high pressure". Nature Chemistry. 9 (5): 440–445. arXiv:1309.3827. Bibcode:2017NatCh...9..440D. doi:10.1038/nchem.2716. PMID 28430195. S2CID 20459726.
Li(–1) has been observed in the gas phase; see R. H. Sloane; H. M. Love (1947). "Surface Formation of Lithium Negative Ions". Nature. 159 (4035): 302–303. Bibcode:1947Natur.159..302S. doi:10.1038/159302a0.
Berthold, Chantsalmaa; Maurer, Johannes; Klerner, Lukas; Harder, Prof. Dr. Sjoerd; Buchner, Dr. Magnus R. (2024-05-31). "Formation, Structure and Reactivity of a Beryllium(0) Complex with Mg^δ+−Be^δ− Bond Polarization". Angewandte Chemie International Edition. 63 (35): e202408422. doi:10.1002/anie.202408422.
Boronski, Josef T.; Crumpton, Agamemnon E.; Wales, Lewis L.; Aldridge, Simon (2023-06-16). "Diberyllocene, a stable compound of Be(I) with a Be–Be bond". Science. 380 (6650): 1147–1149. Bibcode:2023Sci...380.1147B. doi:10.1126/science.adh4419. ISSN 0036-8075. PMID 37319227. S2CID 259166086.
Braunschweig, H.; Dewhurst, R. D.; Hammond, K.; Mies, J.; Radacki, K.; Vargas, A. (2012). "Ambient-Temperature Isolation of a Compound with a Boron-Boron Triple Bond". Science. 336 (6087): 1420–2. Bibcode:2012Sci...336.1420B. doi:10.1126/science.1221138. PMID 22700924. S2CID 206540959.
Zhang, K.Q.; Guo, B.; Braun, V.; Dulick, M.; Bernath, P.F. (1995). "Infrared Emission Spectroscopy of BF and AIF" (PDF). J. Molecular Spectroscopy. 170 (1): 82. Bibcode:1995JMoSp.170...82Z. doi:10.1006/jmsp.1995.1058.
Tetrazoles contain a pair of double-bonded nitrogen atoms with oxidation state 0 in the ring. A Synthesis of the parent 1H-tetrazole, CH₂N₄ (two atoms N(0)) is given in Henry, Ronald A.; Finnegan, William G. (1954). "An Improved Procedure for the Deamination of 5-Aminotetrazole". Journal of the American Chemical Society. 76 (1): 290–291. Bibcode:1954JAChS..76..290H. doi:10.1021/ja01630a086. ISSN 0002-7863.
Gold heptafluoride, synthesized at low temperature, is calculated to be a complex of molecular fluorine with gold pentafluoride, with F-F bonding in the F₂ evidenced by IR spectroscopy; see Himmel, Daniel; Riedel, Sebastian (2007-05-31). "After 20 Years, Theoretical Evidence That "AuF₇" Is Actually AuF₅·F₂". Inorganic Chemistry. 46 (13): 5338–5342. doi:10.1021/ic700431s. PMID 17511450.
Ne(0) has been observed in Cr(CO)₅Ne; see Perutz, Robin N.; Turner, James J. (August 1975). "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. 97 (17): 4791–4800. Bibcode:1975JAChS..97.4791P. doi:10.1021/ja00850a001.
Mg(0) has been synthesized in a compound containing a Na₂Mg₂²⁺ cluster coordinated to a bulky organic ligand; see Rösch, B.; Gentner, T. X.; Eyselein, J.; Langer, J.; Elsen, H.; Li, W.; Harder, S. (2021). "Strongly reducing magnesium(0) complexes". Nature. 592 (7856): 717–721. Bibcode:2021Natur.592..717R. doi:10.1038/s41586-021-03401-w. PMID 33911274. S2CID 233447380
Bernath, P. F.; Black, J. H. & Brault, J. W. (1985). "The spectrum of magnesium hydride" (PDF). Astrophysical Journal. 298: 375. Bibcode:1985ApJ...298..375B. doi:10.1086/163620.. See also Low valent magnesium compounds.
Al(−2) has been observed in Sr₁₄[Al₄]₂[Ge]₃, see Wemdorff, Marco; Röhr, Caroline (2007). "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 (in German). 62 (10): 1227. doi:10.1515/znb-2007-1001. S2CID 94972243.
Al(–1) has been reported in Na₅Al₅; see Haopeng Wang; Xinxing Zhang; Yeon Jae Ko; Andrej Grubisic; Xiang Li; Gerd Ganteför; Hansgeorg Schnöckel; Bryan W. Eichhorn; Mal-Soon Lee; P. Jena; Anil K. Kandalam; Boggavarapu Kiran; Kit H. Bowen (2014). "Aluminum Zintl anion moieties within sodium aluminum clusters". The Journal of Chemical Physics. 140 (5). Bibcode:2014JChPh.140e4301W. doi:10.1063/1.4862989.
Unstable carbonyl of Al(0) has been detected in reaction of Al₂(CH₃)₆ with carbon monoxide; see Sanchez, Ramiro; Arrington, Caleb; Arrington Jr., C. A. (December 1, 1989). "Reaction of trimethylaluminum with carbon monoxide in low-temperature matrixes". American Chemical Society. 111 (25): 9110-9111. Bibcode:1989JAChS.111.9110S. doi:10.1021/ja00207a023. OSTI 6973516.
Dohmeier, C.; Loos, D.; Schnöckel, H. (1996). "Aluminum(I) and Gallium(I) Compounds: Syntheses, Structures, and Reactions". Angewandte Chemie International Edition. 35 (2): 129–149. doi:10.1002/anie.199601291.
Tyte, D. C. (1964). "Red (B2Π–A2σ) Band System of Aluminium Monoxide". Nature. 202 (4930): 383. Bibcode:1964Natur.202..383T. doi:10.1038/202383a0. S2CID 4163250.
Ram, R. S.; et al. (1998). "Fourier Transform Emission Spectroscopy of the A2D–X2P Transition of SiH and SiD" (PDF). J. Mol. Spectr. 190 (2): 341–352. doi:10.1006/jmsp.1998.7582. PMID 9668026.
Wang, Yuzhong; Xie, Yaoming; Wei, Pingrong; King, R. Bruce; Schaefer, Iii; Schleyer, Paul v. R.; Robinson, Gregory H. (2008). "Carbene-Stabilized Diphosphorus". Journal of the American Chemical Society. 130 (45): 14970–1. Bibcode:2008JAChS.13014970W. doi:10.1021/ja807828t. PMID 18937460.
Ellis, Bobby D.; MacDonald, Charles L. B. (2006). "Phosphorus(I) Iodide: A Versatile Metathesis Reagent for the Synthesis of Low Oxidation State Phosphorus Compounds". Inorganic Chemistry. 45 (17): 6864–74. doi:10.1021/ic060186o. PMID 16903744.
Ar(0) has been observed in argon fluorohydride (HArF) and ArCF₂²⁺, see Lockyear, J.F.; Douglas, K.; Price, S.D.; Karwowska, M.; et al. (2010). "Generation of the ArCF₂²⁺ Dication". Journal of Physical Chemistry Letters. 1: 358. doi:10.1021/jz900274p.
John E. Ellis (2006). "Adventures with Substances Containing Metals in Negative Oxidation States". Inorganic Chemistry. 45 (8): 3167–3186. doi:10.1021/ic052110i.
Calcium(I) has been obtained as a dinuclear organometallic complex with an arene dianion, see Krieck, Sven; Görls, Helmar; Yu, Lian; Reiher, Markus; Westerhausen, Matthias (2009). "Stable "Inverse" Sandwich Complex with Unprecedented Organocalcium(I): Crystal Structures of [(thf)2Mg(Br)-C6H2-2,4,6-Ph3] and [(thf)3Ca{μ-C6H3-1,3,5-Ph3}Ca(thf)3]". Journal of the American Chemical Society. 131 (8): 2977–2985. doi:10.1021/ja808524y..
Cloke, F. Geoffrey N.; Khan, Karl & Perutz, Robin N. (1991). "η-Arene complexes of scandium(0) and scandium(II)". J. Chem. Soc., Chem. Commun. (19): 1372–1373. doi:10.1039/C39910001372.
Smith, R. E. (1973). "Diatomic Hydride and Deuteride Spectra of the Second Row Transition Metals". Proceedings of the Royal Society of London. Series A, Mathematical and Physical Sciences. 332 (1588): 113–127. Bibcode:1973RSPSA.332..113S. doi:10.1098/rspa.1973.0015. S2CID 96908213.
McGuire, Joseph C.; Kempter, Charles P. (1960). "Preparation and Properties of Scandium Dihydride". Journal of Chemical Physics. 33 (5): 1584–1585. Bibcode:1960JChPh..33.1584M. doi:10.1063/1.1731452.
Ti(-2) is known in Ti(CO)2−6; see John E. Ellis (2006). "Adventures with Substances Containing Metals in Negative Oxidation States". Inorganic Chemistry. 45 (8): 3167–3186. doi:10.1021/ic052110i.
Jilek, Robert E.; Tripepi, Giovanna; Urnezius, Eugenijus; Brennessel, William W.; Young, Victor G. Jr.; Ellis, John E. (2007). "Zerovalent titanium–sulfur complexes. Novel dithiocarbamato derivatives of Ti(CO)₆:[Ti(CO)₄(S₂CNR₂)]⁻". Chem. Commun. (25): 2639–2641. doi:10.1039/B700808B. PMID 17579764.
Andersson, N.; et al. (2003). "Emission spectra of TiH and TiD near 938 nm". J. Chem. Phys. 118 (8): 10543. Bibcode:2003JChPh.118.3543A. doi:10.1063/1.1539848.
V(–3) is known in V(CO)3−5; see John E. Ellis (2006). "Adventures with Substances Containing Metals in Negative Oxidation States". Inorganic Chemistry. 45 (8): 3167–3186. doi:10.1021/ic052110i.
V(0) is known in V(CO)₆; see John E. Ellis (2006). "Adventures with Substances Containing Metals in Negative Oxidation States". Inorganic Chemistry. 45 (8): 3167–3186. doi:10.1021/ic052110i.
Cr(–4) is known in Na₄Cr(CO)₄; see John E. Ellis (2006). "Adventures with Substances Containing Metals in Negative Oxidation States". Inorganic Chemistry. 45 (8): 3167–3186. doi:10.1021/ic052110i.
Cr(0) is known in Cr(CO)₆; see John E. Ellis (2006). "Adventures with Substances Containing Metals in Negative Oxidation States". Inorganic Chemistry. 45 (8): 3167–3186. doi:10.1021/ic052110i.
Mn(–2) is known in Mn(cod)2−2; see John E. Ellis (2006). "Adventures with Substances Containing Metals in Negative Oxidation States". Inorganic Chemistry. 45 (8): 3167–3186. doi:10.1021/ic052110i.
Ram, R. S.; Bernath, P. F. (2003). "Fourier transform emission spectroscopy of the g⁴Δ–a⁴Δ system of FeCl". Journal of Molecular Spectroscopy. 221 (2): 261. Bibcode:2003JMoSp.221..261R. doi:10.1016/S0022-2852(03)00225-X.
Demazeau, G.; Buffat, B.; Pouchard, M.; Hagenmuller, P. (1982). "Recent developments in the field of high oxidation states of transition elements in oxides stabilization of six-coordinated Iron(V)". Zeitschrift für anorganische und allgemeine Chemie. 491: 60–66. doi:10.1002/zaac.19824910109.
Lu, J.; Jian, J.; Huang, W.; Lin, H.; Li, J; Zhou, M. (2016). "Experimental and theoretical identification of the Fe(VII) oxidation state in FeO₄⁻". Physical Chemistry Chemical Physics. 18 (45): 31125–31131. Bibcode:2016PCCP...1831125L. doi:10.1039/C6CP06753K. PMID 27812577.
Co(–3) is known in Na₃Co(CO)₃; see John E. Ellis (2006). "Adventures with Substances Containing Metals in Negative Oxidation States". Inorganic Chemistry. 45 (8): 3167–3186. doi:10.1021/ic052110i.
Ni(–2) is known in Ni(COD)2−2; see John E. Ellis (2006). "Adventures with Substances Containing Metals in Negative Oxidation States". Inorganic Chemistry. 45 (8): 3167–3186. doi:10.1021/ic052110i.
Ni(0) is known in Ni(CO)₄; see John E. Ellis (2006). "Adventures with Substances Containing Metals in Negative Oxidation States". Inorganic Chemistry. 45 (8): 3167–3186. doi:10.1021/ic052110i.
Pfirrmann, Stefan; Limberg, Christian; Herwig, Christian; Stößer, Reinhard; Ziemer, Burkhard (2009). "A Dinuclear Nickel(I) Dinitrogen Complex and its Reduction in Single-Electron Steps". Angewandte Chemie International Edition. 48 (18): 3357–61. doi:10.1002/anie.200805862. PMID 19322853.
Carnes, Matthew; Buccella, Daniela; Chen, Judy Y.-C.; Ramirez, Arthur P.; Turro, Nicholas J.; Nuckolls, Colin; Steigerwald, Michael (2009). "A Stable Tetraalkyl Complex of Nickel(IV)". Angewandte Chemie International Edition. 48 (2): 290–4. doi:10.1002/anie.200804435. PMID 19021174.
Cu(−2) have been observed as dimeric anions [Cu₄]^2– in La₂Cu₂In; see Changhoon Lee; Myung-Hwan Whangbo (2008). "Late transition metal anions acting as p-metal elements". Solid State Sciences. 10 (4): 444–449. Bibcode:2008SSSci..10..444K. doi:10.1016/j.solidstatesciences.2007.12.001.
Jackson, Ross A.; Evans, Nicholas J.; Babula, Dawid J.; Horsley Downie, Thomas M.; Charman, Rex S. C.; Neale, Samuel E.; Mahon, Mary F.; Liptrot, David J. (2025-01-28). "Nucleophilicity at copper(-I) in a compound with a Cu–Mg bond". Nature Communications. 16 (1): 1101. Bibcode:2025NatCo..16.1101J. doi:10.1038/s41467-025-56544-z. ISSN 2041-1723. PMC 11775243. PMID 39875432.
Moret, Marc-Etienne; Zhang, Limei; Peters, Jonas C. (2013). "A Polar Copper–Boron One-Electron σ-Bond". J. Am. Chem. Soc. 135 (10): 3792–3795. Bibcode:2013JAChS.135.3792M. doi:10.1021/ja4006578. PMID 23418750.
Zn(−2) have been observed (as dimeric and monomeric anions; dimeric ions were initially reported to be [T–T]²⁻, but later shown to be [T–T]⁴⁻ for all these elements) in Ca₅Zn₃ (structure (AE²⁺)₅(T–T)⁴⁻T²⁻⋅4e⁻); see Changhoon Lee; Myung-Hwan Whangbo (2008). "Late transition metal anions acting as p-metal elements". Solid State Sciences. 10 (4): 444–449. Bibcode:2008SSSci..10..444K. doi:10.1016/j.solidstatesciences.2007.12.001. and Changhoon Lee; Myung-Hwan Whangbo; Jürgen Köhler (2010). "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. 636 (1): 36–40. doi:10.1002/zaac.200900421.
Zn(I) has been reported in decamethyldizincocene; see Resa, I.; Carmona, E.; Gutierrez-Puebla, E.; Monge, A. (2004). "Decamethyldizincocene, a Stable Compound of Zn(I) with a Zn-Zn Bond". Science. 305 (5687): 1136–8. Bibcode:2004Sci...305.1136R. doi:10.1126/science.1101356. PMID 15326350. S2CID 38990338.
Hofmann, Patrick (1997). Colture. Ein Programm zur interaktiven Visualisierung von Festkörperstrukturen sowie Synthese, Struktur und Eigenschaften von binären und ternären Alkali- und Erdalkalimetallgalliden (PDF) (Thesis) (in German). PhD Thesis, ETH Zurich. p. 72. doi:10.3929/ethz-a-001859893. hdl:20.500.11850/143357. ISBN 978-3728125972.
Ga(0) is known in gallium monoiodide; see Widdifield, Cory M.; Jurca, Titel; Richeson, Darrin S.; Bryce, David L. (2012-03-16). "Using 69/71Ga solid-state NMR and 127I NQR as probes to elucidate the composition of "GaI"". Polyhedron. 35 (1): 96–100. doi:10.1016/j.poly.2012.01.003. ISSN 0277-5387.
As(−1) has been observed in LiAs; see Reinhard Nesper (1990). "Structure and chemical bonding in zintl-phases containing lithium". Progress in Solid State Chemistry. 20 (1): 1–45. doi:10.1016/0079-6786(90)90006-2.
Abraham, Mariham Y.; Wang, Yuzhong; Xie, Yaoming; Wei, Pingrong; Shaefer III, Henry F.; Schleyer, P. von R.; Robinson, Gregory H. (2010). "Carbene Stabilization of Diarsenic: From Hypervalency to Allotropy". Chemistry: A European Journal. 16 (2): 432–5. doi:10.1002/chem.200902840. PMID 19937872.
Ellis, Bobby D.; MacDonald, Charles L. B. (2004). "Stabilized Arsenic(I) Iodide: A Ready Source of Arsenic Iodide Fragments and a Useful Reagent for the Generation of Clusters". Inorganic Chemistry. 43 (19): 5981–6. doi:10.1021/ic049281s. PMID 15360247.
As(IV) has been observed in arsenic(IV) hydroxide (As(OH)₄) and HAsO⁻; see Kläning, Ulrik K.; Bielski, Benon H. J.; Sehested, K. (1989). "Arsenic(IV). A pulse-radiolysis study". Inorganic Chemistry. 28 (14): 2717–24. doi:10.1021/ic00313a007.
Se(−1) has been observed in diselenides(Se2−2, such as disodium diselenide (Na₂Se₂); see Holleman, Arnold F.; Wiberg, Egon; Wiberg, Nils (2008). Lehrbuch der Anorganischen Chemie (in German) (102 ed.). Walter de Gruyter. p. 829. ISBN 9783110206845. and H. Föppl; E. Busmann; F.-K. Frorath (1962). "Die Kristallstrukturen von α-Na2S2 und K2S2, β-Na2S2 und Na2Se2". Zeitschrift für anorganische und allgemeine Chemie (in German). 314 (1): 12–20. doi:10.1002/zaac.19623140104.
A Se(0) atom has been identified using DFT in [ReOSe(2-pySe)₃]; see Cargnelutti, Roberta; Lang, Ernesto S.; Piquini, Paulo; Abram, Ulrich (2014). "Synthesis and structure of [ReOSe(2-Se-py)3]: A rhenium(V) complex with selenium(0) as a ligand". Inorganic Chemistry Communications. 45: 48–50. doi:10.1016/j.inoche.2014.04.003. ISSN 1387-7003.
Se(III) has been observed in Se₂NBr₃; see Lau, Carsten; Neumüller, Bernhard; Vyboishchikov, Sergei F.; Frenking, Gernot; Dehnicke, Kurt; Hiller, Wolfgang; Herker, Martin (1996). "Se₂NBr₃, Se₂NCl₅, Se₂NCl⁻₆: New Nitride Halides of Selenium(III) and Selenium(IV)". Chemistry: A European Journal. 2 (11): 1393–1396. doi:10.1002/chem.19960021108.
Rb(–1) is known in rubidides; see John E. Ellis (2006). "Adventures with Substances Containing Metals in Negative Oxidation States". Inorganic Chemistry. 45 (8): 3167–3186. doi:10.1021/ic052110i.
Colarusso, P.; Guo, B.; Zhang, K.-Q.; Bernath, P. F. (1996). "High-Resolution Infrared Emission Spectrum of Strontium Monofluoride" (PDF). J. Molecular Spectroscopy. 175 (1): 158. Bibcode:1996JMoSp.175..158C. doi:10.1006/jmsp.1996.0019.
Yttrium and all lanthanides except Ce and Pm have been observed in the oxidation state 0 in bis(1,3,5-tri-t-butylbenzene) complexes, see Cloke, F. Geoffrey N. (1993). "Zero Oxidation State Compounds of Scandium, Yttrium, and the Lanthanides". Chem. Soc. Rev. 22: 17–24. doi:10.1039/CS9932200017. and Arnold, Polly L.; Petrukhina, Marina A.; Bochenkov, Vladimir E.; Shabatina, Tatyana I.; Zagorskii, Vyacheslav V.; Cloke (2003-12-15). "Arene complexation of Sm, Eu, Tm and Yb atoms: a variable temperature spectroscopic investigation". Journal of Organometallic Chemistry. 688 (1–2): 49–55. doi:10.1016/j.jorganchem.2003.08.028.
Zr(–2) is known in Zr(CO)2−6; see John E. Ellis (2006). "Adventures with Substances Containing Metals in Negative Oxidation States". Inorganic Chemistry. 45 (8): 3167–3186. doi:10.1021/ic052110i.
Zr(0) occur in (η⁶-(1,3,5-^tBu)₃C₆H₃)₂Zr and [(η⁵-C₅R₅Zr(CO)₄]⁻, see Chirik, P. J.; Bradley, C. A. (2007). "4.06 - Complexes of Zirconium and Hafnium in Oxidation States 0 to ii". Comprehensive Organometallic Chemistry III. From Fundamentals to Applications. Vol. 4. Elsevier Ltd. pp. 697–739. doi:10.1016/B0-08-045047-4/00062-5. ISBN 9780080450476.
Calderazzo, Fausto; Pampaloni, Guido (January 1992). "Organometallics of groups 4 and 5: Oxidation states II and lower". Journal of Organometallic Chemistry. 423 (3): 307–328. doi:10.1016/0022-328X(92)83126-3.
Ma, Wen; Herbert, F. William; Senanayake, Sanjaya D.; Yildiz, Bilge (2015-03-09). "Non-equilibrium oxidation states of zirconium during early stages of metal oxidation". Applied Physics Letters. 106 (10). Bibcode:2015ApPhL.106j1603M. doi:10.1063/1.4914180. hdl:1721.1/104888. ISSN 0003-6951.
Nb(–3) occurs in Cs₃Nb(CO)_₅; see John E. Ellis (2003). "Metal Carbonyl Anions: from [Fe(CO)₄]₂⁻ to [Hf(CO)₆]₂⁻ and Beyond†". Organometallics. 22 (17): 3322–3338. doi:10.1021/om030105l.
Mo(–4) occurs in Na₄Mo(CO)_₄; see John E. Ellis (2003). "Metal Carbonyl Anions: from [Fe(CO)₄]₂⁻ to [Hf(CO)₆]₂⁻ and Beyond†". Organometallics. 22 (17): 3322–3338. doi:10.1021/om030105l.
Mo(0) occurs in molybdenum hexacarbonyl; see John E. Ellis (2003). "Metal Carbonyl Anions: from [Fe(CO)₄]₂⁻ to [Hf(CO)₆]₂⁻ and Beyond†". Organometallics. 22 (17): 3322–3338. doi:10.1021/om030105l.
Ru(0) is present in the carbonyl-phosphine complex Ru(CO)₂(PPh₃)₃, see Stephane Sentets, Maria del Carmen Rodriguez Martinez, Laure Vendier, Bruno Donnadieu, Vincent Huc, Noël Lugan, and Guy Lavigne (2005). "Instant "Base-Promoted" Generation of Roper's-type Ru(0) Complexes Ru(CO)₂(PR₃)₃ from a Simple Carbonylchlororuthenium(II) Precursor". J. Am. Chem. Soc. 127 (42): 14554–14555. doi:10.1021/ja055066e. PMID 16231891.{{cite journal}}: CS1 maint: multiple names: authors list (link)
Rh(VII) is known in the RhO₃⁺ cation, see Da Silva Santos, Mayara; Stüker, Tony; Flach, Max; Ablyasova, Olesya S.; Timm, Martin; von Issendorff, Bernd; Hirsch, Konstantin; Zamudio-Bayer, Vicente; Riedel, Sebastian; Lau, J. Tobias (2022). "The Highest Oxidation State of Rhodium: Rhodium(VII) in [RhO3]+". Angew. Chem. Int. Ed. 61 (38): e202207688. doi:10.1002/anie.202207688. PMC 9544489. PMID 35818987.
Pd(I) is known in [Pd₂]²⁺ compounds; see Christoph Fricke; Theresa Sperger; Marvin Mendel; Franziska Schoenebeck (2020). "Catalysis with Palladium(I) Dimers". Angewandte Chemie International Edition. 60 (7): 3355–3366. doi:10.1002/anie.202011825. PMC 7898807. PMID 33058375.
Pd(III) has been observed; see Powers, D. C.; Ritter, T. (2011). "Palladium(III) in Synthesis and Catalysis" (PDF). Higher Oxidation State Organopalladium and Platinum Chemistry. Topics in Organometallic Chemistry. Vol. 35. pp. 129–156. Bibcode:2011hoso.book..129P. doi:10.1007/978-3-642-17429-2_6. ISBN 978-3-642-17428-5. PMC 3066514. PMID 21461129. Archived from the original (PDF) on June 12, 2013.
Palladium(V) has been identified in complexes with organosilicon compounds containing pentacoordinate palladium; see Shimada, Shigeru; Li, Yong-Hua; Choe, Yoong-Kee; Tanaka, Masato; Bao, Ming; Uchimaru, Tadafumi (2007). "Multinuclear palladium compounds containing palladium centers ligated by five silicon atoms". Proceedings of the National Academy of Sciences. 104 (19): 7758–7763. Bibcode:2007PNAS..104.7758S. doi:10.1073/pnas.0700450104. PMC 1876520. PMID 17470819.
Ag(−2) have been observed as dimeric and monomeric anions in Ca₅Ag₃, (structure (Ca²⁺)₅(Ag–Ag)⁴⁻Ag²⁻⋅4e⁻); see Changhoon Lee; Myung-Hwan Whangbo; Jürgen Köhler (2010). "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. 636 (1): 36–40. doi:10.1002/zaac.200900421.
The Ag⁻ ion has been observed in metal ammonia solutions: see Tran, N. E.; Lagowski, J. J. (2001). "Metal Ammonia Solutions: Solutions Containing Argentide Ions". Inorganic Chemistry. 40 (5): 1067–68. doi:10.1021/ic000333x.
Ag(0) has been observed in carbonyl complexes in low-temperature matrices: see McIntosh, D.; Ozin, G. A. (1976). "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. 98 (11): 3167–75. Bibcode:1976JAChS..98.3167M. doi:10.1021/ja00427a018.
Cd(−2) have been observed (as dimeric and monomeric anions; dimeric ions were initially reported to be [T–T]²⁻, but later shown to be [T–T]⁴⁻) in Sr₅Cd₃; see Changhoon Lee; Myung-Hwan Whangbo; Jürgen Köhler (2010). "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. 636 (1): 36–40. doi:10.1002/zaac.200900421.
Guloy, A. M.; Corbett, J. D. (1996). "Synthesis, Structure, and Bonding of Two Lanthanum Indium Germanides with Novel Structures and Properties". Inorganic Chemistry. 35 (9): 2616–22. doi:10.1021/ic951378e. PMID 11666477.
Sn(−3) has been observed in [Sn₂]⁶⁻, e.g. in (Ba₂)⁴⁺(Mg₄)⁸⁺Sn⁴⁻(Sn₂)⁶⁻Sn²⁻ (with square (Sn²⁻)_n sheets), see Papoian, Garegin A.; Hoffmann, Roald (2000). "Hypervalent Bonding in One, Two, and Three Dimensions: Extending the Zintl–Klemm Concept to Nonclassical Electron-Rich Networks". Angew. Chem. Int. Ed. 2000 (39): 2408–2448. doi:10.1002/1521-3773(20000717)39:14<2408::aid-anie2408>3.0.co;2-u. PMID 10941096. Retrieved 2015-02-23.
Sb(−2) and Sb(−1) has been observed in [Sb₂]⁴⁻ and ¹_∞[Sb_n]ⁿ⁻, respectively; see Boss, Michael; Petri, Denis; Pickhard, Frank; Zönnchen, Peter; Röhr, Caroline (2005). "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 (in German). 631 (6–7): 1181–1190. doi:10.1002/zaac.200400546.
Anastas Sidiropoulos (2019). "Studies of N-heterocyclic Carbene (NHC) Complexes of the Main Group Elements". p. 39. doi:10.4225/03/5B0F4BDF98F60. S2CID 132399530.
Sb(I) have been observed in organoantimony compounds; see Šimon, Petr; de Proft, Frank; Jambor, Roman; Růžička, Aleš; Dostál, Libor (2010). "Monomeric Organoantimony(I) and Organobismuth(I) Compounds Stabilized by an NCN Chelating Ligand: Syntheses and Structures". Angewandte Chemie International Edition. 49 (32): 5468–5471. doi:10.1002/anie.201002209. PMID 20602393.
Sb(IV) has been observed in [SbCl₆]²⁻, see Nobuyoshi Shinohara; Masaaki Ohsima (2000). "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. 73 (7): 1599–1604. doi:10.1246/bcsj.73.1599.
I(II) is known to exist in monoxide (IO); see Nikitin, I V (31 August 2008). "Halogen monoxides". Russian Chemical Reviews. 77 (8): 739–749. Bibcode:2008RuCRv..77..739N. doi:10.1070/RC2008v077n08ABEH003788. S2CID 250898175.
Dye, J. L. (1979). "Compounds of Alkali Metal Anions". Angewandte Chemie International Edition. 18 (8): 587–598. doi:10.1002/anie.197905871.
Xu, Wei; Lerner, Michael M. (2018). "A New and Facile Route Using Electride Solutions to Intercalate Alkaline Earth Ions into Graphite". Chemistry of Materials. 30 (19): 6930–6935. doi:10.1021/acs.chemmater.8b03421. S2CID 105295721.
La(I), Pr(I), Tb(I), Tm(I), and Yb(I) have been observed in MB₈⁻ clusters; see Li, Wan-Lu; Chen, Teng-Teng; Chen, Wei-Jia; Li, Jun; Wang, Lai-Sheng (2021). "Monovalent lanthanide(I) in borozene complexes". Nature Communications. 12 (1): 6467. Bibcode:2021NatCo..12.6467L. doi:10.1038/s41467-021-26785-9. PMC 8578558. PMID 34753931.
Chen, Xin; et al. (2019-12-13). "Lanthanides with Unusually Low Oxidation States in the PrB₃^– and PrB₄^– Boride Clusters". Inorganic Chemistry. 58 (1): 411–418. doi:10.1021/acs.inorgchem.8b02572. PMID 30543295. S2CID 56148031.
All the lanthanides, except Pm, in the +2 oxidation state have been observed in organometallic molecular complexes, see Lanthanides Topple Assumptions and Meyer, G. (2014). "All the Lanthanides Do It and Even Uranium Does Oxidation State +2". Angewandte Chemie International Edition. 53 (14): 3550–51. doi:10.1002/anie.201311325. PMID 24616202.. Additionally, all the lanthanides (La–Lu) form dihydrides (LnH₂), dicarbides (LnC₂), monosulfides (LnS), monoselenides (LnSe), and monotellurides (LnTe), but for most elements these compounds have Ln³⁺ ions with electrons delocalized into conduction bands, e. g. Ln³⁺(H⁻)₂(e⁻).
SmB₆⁻ cluster anion has been reported and contains Sm in rare oxidation state of +1; see Paul, J. Robinson; Xinxing, Zhang; Tyrel, McQueen; Kit, H. Bowen; Anastassia, N. Alexandrova (2017). "SmB₆^– Cluster Anion: Covalency Involving f Orbitals". J. Phys. Chem. A 2017,^? 121,^? 8,^? 1849–1854. 121 (8): 1849–1854. Bibcode:2017JPCA..121.1849R. doi:10.1021/acs.jpca.7b00247. PMID 28182423. S2CID 3723987..
Hf(–2) occurs in Hf(CO)_₆²⁻; see John E. Ellis (2003). "Metal Carbonyl Anions: from [Fe(CO)₄]₂⁻ to [Hf(CO)₆]₂⁻ and Beyond†". Organometallics. 22 (17): 3322–3338. doi:10.1021/om030105l.
Hf(0) occur in (η⁶-(1,3,5-^tBu)₃C₆H₃)₂Hf and [(η⁵-C₅R₅Hf(CO)₄]⁻, see Chirik, P. J.; Bradley, C. A. (2007). "4.06 - Complexes of Zirconium and Hafnium in Oxidation States 0 to ii". Comprehensive Organometallic Chemistry III. From Fundamentals to Applications. Vol. 4. Elsevier Ltd. pp. 697–739. doi:10.1016/B0-08-045047-4/00062-5. ISBN 9780080450476.
Ta(–3) occurs in Ta(CO)_₅³⁻; see John E. Ellis (2003). "Metal Carbonyl Anions: from [Fe(CO)₄]₂⁻ to [Hf(CO)₆]₂⁻ and Beyond†". Organometallics. 22 (17): 3322–3338. doi:10.1021/om030105l.
Ta(0) is known in Ta(CNDipp)₆; see Khetpakorn Chakarawet; Zachary W. Davis-Gilbert; Stephanie R. Harstad; Victor G. Young Jr.; Jeffrey R. Long; John E. Ellis (2017). "Ta(CNDipp)6: An Isocyanide Analogue of Hexacarbonyltantalum(0)". Angewandte Chemie International Edition. 56 (35): 10577–10581. doi:10.1002/anie.201706323. PMID 28697283. Additionally, Ta(0) has also been previously reported in Ta(bipy)₃, but this has been proven to contain Ta(V).
W(−4) is known in W(CO)4−4; see John E. Ellis (2006). "Adventures with Substances Containing Metals in Negative Oxidation States". Inorganic Chemistry. 45 (8): 3167–3186. doi:10.1021/ic052110i.
W(0) is known in W(CO)₆; see John E. Ellis (2006). "Adventures with Substances Containing Metals in Negative Oxidation States". Inorganic Chemistry. 45 (8): 3167–3186. doi:10.1021/ic052110i.
Re(0) is known in Re₂(CO)₁₀; see John E. Ellis (2006). "Adventures with Substances Containing Metals in Negative Oxidation States". Inorganic Chemistry. 45 (8): 3167–3186. doi:10.1021/ic052110i.
Wang, Guanjun; Zhou, Mingfei; Goettel, James T.; Schrobilgen, Gary G.; Su, Jing; Li, Jun; Schlöder, Tobias; Riedel, Sebastian (2014). "Identification of an iridium-containing compound with a formal oxidation state of IX". Nature. 514 (7523): 475–477. Bibcode:2014Natur.514..475W. doi:10.1038/nature13795. PMID 25341786. S2CID 4463905.
Mézaille, Nicolas; Avarvari, Narcis; Maigrot, Nicole; Ricard, Louis; Mathey, François; Le Floch, Pascal; Cataldo, Laurent; Berclaz, Théo; Geoffroy, Michel (1999). "Gold(I) and Gold(0) Complexes of Phosphinine-Based Macrocycles". Angewandte Chemie International Edition. 38 (21): 3194–3197. doi:10.1002/(SICI)1521-3773(19991102)38:21<3194::AID-ANIE3194>3.0.CO;2-O. PMID 10556900.
Brauer, G.; Haucke, W. (1936-06-01). "Kristallstruktur der intermetallischen Phasen MgAu und MgHg". Zeitschrift für Physikalische Chemie. 33B (1): 304–310. doi:10.1515/zpch-1936-3327. ISSN 2196-7156. MgHg then lends itself to an oxidation state of +2 for Mg and -2 for Hg because it consists entirely of these polar bonds with no evidence of electron unpairing. (translated)
Dong, Z.-C.; Corbett, J. D. (1996). "Na₂₃K₉Tl_15.3: An Unusual Zintl Compound Containing Apparent Tl₅⁷⁻, Tl₄⁸⁻, Tl₃⁷⁻, and Tl⁵⁻ Anions". Inorganic Chemistry. 35 (11): 3107–12. doi:10.1021/ic960014z. PMID 11666505.
Pb(0) carbonyls have been observered in reaction between lead atoms and carbon monoxide; see Ling, Jiang; Qiang, Xu (2005). "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. 122 (3): 34505. Bibcode:2005JChPh.122c4505J. doi:10.1063/1.1834915. ISSN 0021-9606. PMID 15740207.
Bi(0) state exists in a N-heterocyclic carbene complex of dibismuthene; see Deka, Rajesh; Orthaber, Andreas (May 9, 2022). "Carbene chemistry of arsenic, antimony, and bismuth: origin, evolution and future prospects". Royal Society of Chemistry. 51 (22): 8540–8556. doi:10.1039/d2dt00755j. PMID 35578901. S2CID 248675805.
Thayer, John S. (2010). "Relativistic Effects and the Chemistry of the Heavier Main Group Elements". Relativistic Methods for Chemists. Challenges and Advances in Computational Chemistry and Physics. Vol. 10. p. 78. doi:10.1007/978-1-4020-9975-5_2. ISBN 978-1-4020-9974-8.
Th(-I) and U(-I) have been detected in the gas phase as octacarbonyl anions; see Chaoxian, Chi; Sudip, Pan; Jiaye, Jin; Luyan, Meng; Mingbiao, Luo; Lili, Zhao; Mingfei, Zhou; Gernot, Frenking (2019). "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. 25 (50): 11772–11784. doi:10.1002/chem.201902625. ISSN 0947-6539. PMC 6772027. PMID 31276242.
Np(II), (III) and (IV) have been observed, see Dutkiewicz, Michał S.; Apostolidis, Christos; Walter, Olaf; Arnold, Polly L (2017). "Reduction chemistry of neptunium cyclopentadienide complexes: from structure to understanding". Chem. Sci. 8 (4): 2553–2561. doi:10.1039/C7SC00034K. PMC 5431675. PMID 28553487.
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. (2017). "Identification of the Formal +2 Oxidation State of Plutonium: Synthesis and Characterization of {Pu^II[C₅H₃(SiMe₃)₂]₃}⁻". J. Am. Chem. Soc. 139 (11): 3970–3973. doi:10.1021/jacs.7b00706. PMID 28235179.
Preparation of plutonium(VIII) compounds has been claimed, see Zaitsevskii, Andréi; Mosyagin, Nikolai S.; Titov, Anatoly V.; Kiselev, Yuri M. (July 21, 2013). "Relativistic density functional theory modeling of plutonium and americium higher oxide molecules". The Journal of Chemical Physics. 139 (3): 034307. Bibcode:2013JChPh.139c4307Z. doi:10.1063/1.4813284. PMID 23883027. and Kiselev, Yu. M.; Nikonov, M. V.; Dolzhenko, V. D.; Ermilov, A. Yu.; Tananaev, I. G.; Myasoedov, B. F. (January 17, 2014). "On existence and properties of plutonium(VIII) derivatives". Radiochimica Acta. 102 (3): 227–237. doi:10.1515/ract-2014-2146. S2CID 100915090. But their existence has been partially disproven, see Fedosseev, Alexander M.; Bessonov, Alexi A.; Shilov, Vladimir P. (September 5, 2022). "Is octavalent plutonium really formed during oxidation in alkaline aqueous solutions?". Radiochimica Acta. 110 (12): 955–959. doi:10.1515/ract-2022-0056.
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Disodium helide, (Na⁺)₂He(e⁻)₂, has been synthesized at high pressure, see 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 (6 February 2017). "A stable compound of helium and sodium at high pressure". Nature Chemistry. 9 (5): 440–445. arXiv:1309.3827. Bibcode:2017NatCh...9..440D. doi:10.1038/nchem.2716. PMID 28430195. S2CID 20459726.
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Tetrazoles contain a pair of double-bonded nitrogen atoms with oxidation state 0 in the ring. A Synthesis of the parent 1H-tetrazole, CH₂N₄ (two atoms N(0)) is given in Henry, Ronald A.; Finnegan, William G. (1954). "An Improved Procedure for the Deamination of 5-Aminotetrazole". Journal of the American Chemical Society. 76 (1): 290–291. Bibcode:1954JAChS..76..290H. doi:10.1021/ja01630a086. ISSN 0002-7863.
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Mg(0) has been synthesized in a compound containing a Na₂Mg₂²⁺ cluster coordinated to a bulky organic ligand; see Rösch, B.; Gentner, T. X.; Eyselein, J.; Langer, J.; Elsen, H.; Li, W.; Harder, S. (2021). "Strongly reducing magnesium(0) complexes". Nature. 592 (7856): 717–721. Bibcode:2021Natur.592..717R. doi:10.1038/s41586-021-03401-w. PMID 33911274. S2CID 233447380
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Al(–1) has been reported in Na₅Al₅; see Haopeng Wang; Xinxing Zhang; Yeon Jae Ko; Andrej Grubisic; Xiang Li; Gerd Ganteför; Hansgeorg Schnöckel; Bryan W. Eichhorn; Mal-Soon Lee; P. Jena; Anil K. Kandalam; Boggavarapu Kiran; Kit H. Bowen (2014). "Aluminum Zintl anion moieties within sodium aluminum clusters". The Journal of Chemical Physics. 140 (5). Bibcode:2014JChPh.140e4301W. doi:10.1063/1.4862989.
Unstable carbonyl of Al(0) has been detected in reaction of Al₂(CH₃)₆ with carbon monoxide; see Sanchez, Ramiro; Arrington, Caleb; Arrington Jr., C. A. (December 1, 1989). "Reaction of trimethylaluminum with carbon monoxide in low-temperature matrixes". American Chemical Society. 111 (25): 9110-9111. Bibcode:1989JAChS.111.9110S. doi:10.1021/ja00207a023. OSTI 6973516.
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McGuire, Joseph C.; Kempter, Charles P. (1960). "Preparation and Properties of Scandium Dihydride". Journal of Chemical Physics. 33 (5): 1584–1585. Bibcode:1960JChPh..33.1584M. doi:10.1063/1.1731452.
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Jackson, Ross A.; Evans, Nicholas J.; Babula, Dawid J.; Horsley Downie, Thomas M.; Charman, Rex S. C.; Neale, Samuel E.; Mahon, Mary F.; Liptrot, David J. (2025-01-28). "Nucleophilicity at copper(-I) in a compound with a Cu–Mg bond". Nature Communications. 16 (1): 1101. Bibcode:2025NatCo..16.1101J. doi:10.1038/s41467-025-56544-z. ISSN 2041-1723. PMC 11775243. PMID 39875432.
Moret, Marc-Etienne; Zhang, Limei; Peters, Jonas C. (2013). "A Polar Copper–Boron One-Electron σ-Bond". J. Am. Chem. Soc. 135 (10): 3792–3795. Bibcode:2013JAChS.135.3792M. doi:10.1021/ja4006578. PMID 23418750.
Zn(−2) have been observed (as dimeric and monomeric anions; dimeric ions were initially reported to be [T–T]²⁻, but later shown to be [T–T]⁴⁻ for all these elements) in Ca₅Zn₃ (structure (AE²⁺)₅(T–T)⁴⁻T²⁻⋅4e⁻); see Changhoon Lee; Myung-Hwan Whangbo (2008). "Late transition metal anions acting as p-metal elements". Solid State Sciences. 10 (4): 444–449. Bibcode:2008SSSci..10..444K. doi:10.1016/j.solidstatesciences.2007.12.001. and Changhoon Lee; Myung-Hwan Whangbo; Jürgen Köhler (2010). "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. 636 (1): 36–40. doi:10.1002/zaac.200900421.
Zn(I) has been reported in decamethyldizincocene; see Resa, I.; Carmona, E.; Gutierrez-Puebla, E.; Monge, A. (2004). "Decamethyldizincocene, a Stable Compound of Zn(I) with a Zn-Zn Bond". Science. 305 (5687): 1136–8. Bibcode:2004Sci...305.1136R. doi:10.1126/science.1101356. PMID 15326350. S2CID 38990338.
Colarusso, P.; Guo, B.; Zhang, K.-Q.; Bernath, P. F. (1996). "High-Resolution Infrared Emission Spectrum of Strontium Monofluoride" (PDF). J. Molecular Spectroscopy. 175 (1): 158. Bibcode:1996JMoSp.175..158C. doi:10.1006/jmsp.1996.0019.
Ma, Wen; Herbert, F. William; Senanayake, Sanjaya D.; Yildiz, Bilge (2015-03-09). "Non-equilibrium oxidation states of zirconium during early stages of metal oxidation". Applied Physics Letters. 106 (10). Bibcode:2015ApPhL.106j1603M. doi:10.1063/1.4914180. hdl:1721.1/104888. ISSN 0003-6951.
Pd(III) has been observed; see Powers, D. C.; Ritter, T. (2011). "Palladium(III) in Synthesis and Catalysis" (PDF). Higher Oxidation State Organopalladium and Platinum Chemistry. Topics in Organometallic Chemistry. Vol. 35. pp. 129–156. Bibcode:2011hoso.book..129P. doi:10.1007/978-3-642-17429-2_6. ISBN 978-3-642-17428-5. PMC 3066514. PMID 21461129. Archived from the original (PDF) on June 12, 2013.
Palladium(V) has been identified in complexes with organosilicon compounds containing pentacoordinate palladium; see Shimada, Shigeru; Li, Yong-Hua; Choe, Yoong-Kee; Tanaka, Masato; Bao, Ming; Uchimaru, Tadafumi (2007). "Multinuclear palladium compounds containing palladium centers ligated by five silicon atoms". Proceedings of the National Academy of Sciences. 104 (19): 7758–7763. Bibcode:2007PNAS..104.7758S. doi:10.1073/pnas.0700450104. PMC 1876520. PMID 17470819.
Ag(0) has been observed in carbonyl complexes in low-temperature matrices: see McIntosh, D.; Ozin, G. A. (1976). "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. 98 (11): 3167–75. Bibcode:1976JAChS..98.3167M. doi:10.1021/ja00427a018.
I(II) is known to exist in monoxide (IO); see Nikitin, I V (31 August 2008). "Halogen monoxides". Russian Chemical Reviews. 77 (8): 739–749. Bibcode:2008RuCRv..77..739N. doi:10.1070/RC2008v077n08ABEH003788. S2CID 250898175.
La(I), Pr(I), Tb(I), Tm(I), and Yb(I) have been observed in MB₈⁻ clusters; see Li, Wan-Lu; Chen, Teng-Teng; Chen, Wei-Jia; Li, Jun; Wang, Lai-Sheng (2021). "Monovalent lanthanide(I) in borozene complexes". Nature Communications. 12 (1): 6467. Bibcode:2021NatCo..12.6467L. doi:10.1038/s41467-021-26785-9. PMC 8578558. PMID 34753931.
SmB₆⁻ cluster anion has been reported and contains Sm in rare oxidation state of +1; see Paul, J. Robinson; Xinxing, Zhang; Tyrel, McQueen; Kit, H. Bowen; Anastassia, N. Alexandrova (2017). "SmB₆^– Cluster Anion: Covalency Involving f Orbitals". J. Phys. Chem. A 2017,^? 121,^? 8,^? 1849–1854. 121 (8): 1849–1854. Bibcode:2017JPCA..121.1849R. doi:10.1021/acs.jpca.7b00247. PMID 28182423. S2CID 3723987..
Wang, Guanjun; Zhou, Mingfei; Goettel, James T.; Schrobilgen, Gary G.; Su, Jing; Li, Jun; Schlöder, Tobias; Riedel, Sebastian (2014). "Identification of an iridium-containing compound with a formal oxidation state of IX". Nature. 514 (7523): 475–477. Bibcode:2014Natur.514..475W. doi:10.1038/nature13795. PMID 25341786. S2CID 4463905.
Pb(0) carbonyls have been observered in reaction between lead atoms and carbon monoxide; see Ling, Jiang; Qiang, Xu (2005). "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. 122 (3): 34505. Bibcode:2005JChPh.122c4505J. doi:10.1063/1.1834915. ISSN 0021-9606. PMID 15740207.
Preparation of plutonium(VIII) compounds has been claimed, see Zaitsevskii, Andréi; Mosyagin, Nikolai S.; Titov, Anatoly V.; Kiselev, Yuri M. (July 21, 2013). "Relativistic density functional theory modeling of plutonium and americium higher oxide molecules". The Journal of Chemical Physics. 139 (3): 034307. Bibcode:2013JChPh.139c4307Z. doi:10.1063/1.4813284. PMID 23883027. and Kiselev, Yu. M.; Nikonov, M. V.; Dolzhenko, V. D.; Ermilov, A. Yu.; Tananaev, I. G.; Myasoedov, B. F. (January 17, 2014). "On existence and properties of plutonium(VIII) derivatives". Radiochimica Acta. 102 (3): 227–237. doi:10.1515/ract-2014-2146. S2CID 100915090. But their existence has been partially disproven, see Fedosseev, Alexander M.; Bessonov, Alexi A.; Shilov, Vladimir P. (September 5, 2022). "Is octavalent plutonium really formed during oxidation in alkaline aqueous solutions?". Radiochimica Acta. 110 (12): 955–959. doi:10.1515/ract-2022-0056.
Domanov, V. P.; Lobanov, Yu. V. (October 2011). "Formation of volatile curium(VI) trioxide CmO₃". Radiochemistry. 53 (5). SP MAIK Nauka/Interperiodica: 453–6. Bibcode:2011Radch..53..453D. doi:10.1134/S1066362211050018. S2CID 98052484.
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chem.harvard.edu

Pd(III) has been observed; see Powers, D. C.; Ritter, T. (2011). "Palladium(III) in Synthesis and Catalysis" (PDF). Higher Oxidation State Organopalladium and Platinum Chemistry. Topics in Organometallic Chemistry. Vol. 35. pp. 129–156. Bibcode:2011hoso.book..129P. doi:10.1007/978-3-642-17429-2_6. ISBN 978-3-642-17428-5. PMC 3066514. PMID 21461129. Archived from the original (PDF) on June 12, 2013.

iaea.org

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Hf(I) has been observed in hafnium monobromide (HfBr), see Marek, G.S.; Troyanov, S.I.; Tsirel'nikov, V.I. (1979). "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 (in Russian). 24 (4): 890–893.

iupac.org

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old.iupac.org

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Wang, G.; Zhou, M.; Goettel, G. T.; Schrobilgen, G. J.; Su, J.; Li, J.; Schlöder, T.; Riedel, S. (2014). "Identification of an iridium-containing compound with a formal oxidation state of IX". Nature. 514 (7523): 475–477. Bibcode:2014Natur.514..475W. doi:10.1038/nature13795. PMID 25341786. S2CID 4463905.
Yu, Haoyu S.; Truhlar, Donald G. (2016). "Oxidation State 10 Exists". Angewandte Chemie International Edition. 55 (31): 9004–9006. doi:10.1002/anie.201604670. PMID 27273799.
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Disodium helide, (Na⁺)₂He(e⁻)₂, has been synthesized at high pressure, see 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 (6 February 2017). "A stable compound of helium and sodium at high pressure". Nature Chemistry. 9 (5): 440–445. arXiv:1309.3827. Bibcode:2017NatCh...9..440D. doi:10.1038/nchem.2716. PMID 28430195. S2CID 20459726.
Boronski, Josef T.; Crumpton, Agamemnon E.; Wales, Lewis L.; Aldridge, Simon (2023-06-16). "Diberyllocene, a stable compound of Be(I) with a Be–Be bond". Science. 380 (6650): 1147–1149. Bibcode:2023Sci...380.1147B. doi:10.1126/science.adh4419. ISSN 0036-8075. PMID 37319227. S2CID 259166086.
Braunschweig, H.; Dewhurst, R. D.; Hammond, K.; Mies, J.; Radacki, K.; Vargas, A. (2012). "Ambient-Temperature Isolation of a Compound with a Boron-Boron Triple Bond". Science. 336 (6087): 1420–2. Bibcode:2012Sci...336.1420B. doi:10.1126/science.1221138. PMID 22700924. S2CID 206540959.
Gold heptafluoride, synthesized at low temperature, is calculated to be a complex of molecular fluorine with gold pentafluoride, with F-F bonding in the F₂ evidenced by IR spectroscopy; see Himmel, Daniel; Riedel, Sebastian (2007-05-31). "After 20 Years, Theoretical Evidence That "AuF₇" Is Actually AuF₅·F₂". Inorganic Chemistry. 46 (13): 5338–5342. doi:10.1021/ic700431s. PMID 17511450.
Mg(0) has been synthesized in a compound containing a Na₂Mg₂²⁺ cluster coordinated to a bulky organic ligand; see Rösch, B.; Gentner, T. X.; Eyselein, J.; Langer, J.; Elsen, H.; Li, W.; Harder, S. (2021). "Strongly reducing magnesium(0) complexes". Nature. 592 (7856): 717–721. Bibcode:2021Natur.592..717R. doi:10.1038/s41586-021-03401-w. PMID 33911274. S2CID 233447380
Ram, R. S.; et al. (1998). "Fourier Transform Emission Spectroscopy of the A2D–X2P Transition of SiH and SiD" (PDF). J. Mol. Spectr. 190 (2): 341–352. doi:10.1006/jmsp.1998.7582. PMID 9668026.
Wang, Yuzhong; Xie, Yaoming; Wei, Pingrong; King, R. Bruce; Schaefer, Iii; Schleyer, Paul v. R.; Robinson, Gregory H. (2008). "Carbene-Stabilized Diphosphorus". Journal of the American Chemical Society. 130 (45): 14970–1. Bibcode:2008JAChS.13014970W. doi:10.1021/ja807828t. PMID 18937460.
Ellis, Bobby D.; MacDonald, Charles L. B. (2006). "Phosphorus(I) Iodide: A Versatile Metathesis Reagent for the Synthesis of Low Oxidation State Phosphorus Compounds". Inorganic Chemistry. 45 (17): 6864–74. doi:10.1021/ic060186o. PMID 16903744.
Jilek, Robert E.; Tripepi, Giovanna; Urnezius, Eugenijus; Brennessel, William W.; Young, Victor G. Jr.; Ellis, John E. (2007). "Zerovalent titanium–sulfur complexes. Novel dithiocarbamato derivatives of Ti(CO)₆:[Ti(CO)₄(S₂CNR₂)]⁻". Chem. Commun. (25): 2639–2641. doi:10.1039/B700808B. PMID 17579764.
Lu, J.; Jian, J.; Huang, W.; Lin, H.; Li, J; Zhou, M. (2016). "Experimental and theoretical identification of the Fe(VII) oxidation state in FeO₄⁻". Physical Chemistry Chemical Physics. 18 (45): 31125–31131. Bibcode:2016PCCP...1831125L. doi:10.1039/C6CP06753K. PMID 27812577.
Pfirrmann, Stefan; Limberg, Christian; Herwig, Christian; Stößer, Reinhard; Ziemer, Burkhard (2009). "A Dinuclear Nickel(I) Dinitrogen Complex and its Reduction in Single-Electron Steps". Angewandte Chemie International Edition. 48 (18): 3357–61. doi:10.1002/anie.200805862. PMID 19322853.
Carnes, Matthew; Buccella, Daniela; Chen, Judy Y.-C.; Ramirez, Arthur P.; Turro, Nicholas J.; Nuckolls, Colin; Steigerwald, Michael (2009). "A Stable Tetraalkyl Complex of Nickel(IV)". Angewandte Chemie International Edition. 48 (2): 290–4. doi:10.1002/anie.200804435. PMID 19021174.
Jackson, Ross A.; Evans, Nicholas J.; Babula, Dawid J.; Horsley Downie, Thomas M.; Charman, Rex S. C.; Neale, Samuel E.; Mahon, Mary F.; Liptrot, David J. (2025-01-28). "Nucleophilicity at copper(-I) in a compound with a Cu–Mg bond". Nature Communications. 16 (1): 1101. Bibcode:2025NatCo..16.1101J. doi:10.1038/s41467-025-56544-z. ISSN 2041-1723. PMC 11775243. PMID 39875432.
Moret, Marc-Etienne; Zhang, Limei; Peters, Jonas C. (2013). "A Polar Copper–Boron One-Electron σ-Bond". J. Am. Chem. Soc. 135 (10): 3792–3795. Bibcode:2013JAChS.135.3792M. doi:10.1021/ja4006578. PMID 23418750.
Zn(I) has been reported in decamethyldizincocene; see Resa, I.; Carmona, E.; Gutierrez-Puebla, E.; Monge, A. (2004). "Decamethyldizincocene, a Stable Compound of Zn(I) with a Zn-Zn Bond". Science. 305 (5687): 1136–8. Bibcode:2004Sci...305.1136R. doi:10.1126/science.1101356. PMID 15326350. S2CID 38990338.
Abraham, Mariham Y.; Wang, Yuzhong; Xie, Yaoming; Wei, Pingrong; Shaefer III, Henry F.; Schleyer, P. von R.; Robinson, Gregory H. (2010). "Carbene Stabilization of Diarsenic: From Hypervalency to Allotropy". Chemistry: A European Journal. 16 (2): 432–5. doi:10.1002/chem.200902840. PMID 19937872.
Ellis, Bobby D.; MacDonald, Charles L. B. (2004). "Stabilized Arsenic(I) Iodide: A Ready Source of Arsenic Iodide Fragments and a Useful Reagent for the Generation of Clusters". Inorganic Chemistry. 43 (19): 5981–6. doi:10.1021/ic049281s. PMID 15360247.
Ru(0) is present in the carbonyl-phosphine complex Ru(CO)₂(PPh₃)₃, see Stephane Sentets, Maria del Carmen Rodriguez Martinez, Laure Vendier, Bruno Donnadieu, Vincent Huc, Noël Lugan, and Guy Lavigne (2005). "Instant "Base-Promoted" Generation of Roper's-type Ru(0) Complexes Ru(CO)₂(PR₃)₃ from a Simple Carbonylchlororuthenium(II) Precursor". J. Am. Chem. Soc. 127 (42): 14554–14555. doi:10.1021/ja055066e. PMID 16231891.{{cite journal}}: CS1 maint: multiple names: authors list (link)
Rh(VII) is known in the RhO₃⁺ cation, see Da Silva Santos, Mayara; Stüker, Tony; Flach, Max; Ablyasova, Olesya S.; Timm, Martin; von Issendorff, Bernd; Hirsch, Konstantin; Zamudio-Bayer, Vicente; Riedel, Sebastian; Lau, J. Tobias (2022). "The Highest Oxidation State of Rhodium: Rhodium(VII) in [RhO3]+". Angew. Chem. Int. Ed. 61 (38): e202207688. doi:10.1002/anie.202207688. PMC 9544489. PMID 35818987.
Pd(I) is known in [Pd₂]²⁺ compounds; see Christoph Fricke; Theresa Sperger; Marvin Mendel; Franziska Schoenebeck (2020). "Catalysis with Palladium(I) Dimers". Angewandte Chemie International Edition. 60 (7): 3355–3366. doi:10.1002/anie.202011825. PMC 7898807. PMID 33058375.
Pd(III) has been observed; see Powers, D. C.; Ritter, T. (2011). "Palladium(III) in Synthesis and Catalysis" (PDF). Higher Oxidation State Organopalladium and Platinum Chemistry. Topics in Organometallic Chemistry. Vol. 35. pp. 129–156. Bibcode:2011hoso.book..129P. doi:10.1007/978-3-642-17429-2_6. ISBN 978-3-642-17428-5. PMC 3066514. PMID 21461129. Archived from the original (PDF) on June 12, 2013.
Palladium(V) has been identified in complexes with organosilicon compounds containing pentacoordinate palladium; see Shimada, Shigeru; Li, Yong-Hua; Choe, Yoong-Kee; Tanaka, Masato; Bao, Ming; Uchimaru, Tadafumi (2007). "Multinuclear palladium compounds containing palladium centers ligated by five silicon atoms". Proceedings of the National Academy of Sciences. 104 (19): 7758–7763. Bibcode:2007PNAS..104.7758S. doi:10.1073/pnas.0700450104. PMC 1876520. PMID 17470819.
Guloy, A. M.; Corbett, J. D. (1996). "Synthesis, Structure, and Bonding of Two Lanthanum Indium Germanides with Novel Structures and Properties". Inorganic Chemistry. 35 (9): 2616–22. doi:10.1021/ic951378e. PMID 11666477.
Sn(−3) has been observed in [Sn₂]⁶⁻, e.g. in (Ba₂)⁴⁺(Mg₄)⁸⁺Sn⁴⁻(Sn₂)⁶⁻Sn²⁻ (with square (Sn²⁻)_n sheets), see Papoian, Garegin A.; Hoffmann, Roald (2000). "Hypervalent Bonding in One, Two, and Three Dimensions: Extending the Zintl–Klemm Concept to Nonclassical Electron-Rich Networks". Angew. Chem. Int. Ed. 2000 (39): 2408–2448. doi:10.1002/1521-3773(20000717)39:14<2408::aid-anie2408>3.0.co;2-u. PMID 10941096. Retrieved 2015-02-23.
Sb(I) have been observed in organoantimony compounds; see Šimon, Petr; de Proft, Frank; Jambor, Roman; Růžička, Aleš; Dostál, Libor (2010). "Monomeric Organoantimony(I) and Organobismuth(I) Compounds Stabilized by an NCN Chelating Ligand: Syntheses and Structures". Angewandte Chemie International Edition. 49 (32): 5468–5471. doi:10.1002/anie.201002209. PMID 20602393.
La(I), Pr(I), Tb(I), Tm(I), and Yb(I) have been observed in MB₈⁻ clusters; see Li, Wan-Lu; Chen, Teng-Teng; Chen, Wei-Jia; Li, Jun; Wang, Lai-Sheng (2021). "Monovalent lanthanide(I) in borozene complexes". Nature Communications. 12 (1): 6467. Bibcode:2021NatCo..12.6467L. doi:10.1038/s41467-021-26785-9. PMC 8578558. PMID 34753931.
Chen, Xin; et al. (2019-12-13). "Lanthanides with Unusually Low Oxidation States in the PrB₃^– and PrB₄^– Boride Clusters". Inorganic Chemistry. 58 (1): 411–418. doi:10.1021/acs.inorgchem.8b02572. PMID 30543295. S2CID 56148031.
All the lanthanides, except Pm, in the +2 oxidation state have been observed in organometallic molecular complexes, see Lanthanides Topple Assumptions and Meyer, G. (2014). "All the Lanthanides Do It and Even Uranium Does Oxidation State +2". Angewandte Chemie International Edition. 53 (14): 3550–51. doi:10.1002/anie.201311325. PMID 24616202.. Additionally, all the lanthanides (La–Lu) form dihydrides (LnH₂), dicarbides (LnC₂), monosulfides (LnS), monoselenides (LnSe), and monotellurides (LnTe), but for most elements these compounds have Ln³⁺ ions with electrons delocalized into conduction bands, e. g. Ln³⁺(H⁻)₂(e⁻).
SmB₆⁻ cluster anion has been reported and contains Sm in rare oxidation state of +1; see Paul, J. Robinson; Xinxing, Zhang; Tyrel, McQueen; Kit, H. Bowen; Anastassia, N. Alexandrova (2017). "SmB₆^– Cluster Anion: Covalency Involving f Orbitals". J. Phys. Chem. A 2017,^? 121,^? 8,^? 1849–1854. 121 (8): 1849–1854. Bibcode:2017JPCA..121.1849R. doi:10.1021/acs.jpca.7b00247. PMID 28182423. S2CID 3723987..
Ta(0) is known in Ta(CNDipp)₆; see Khetpakorn Chakarawet; Zachary W. Davis-Gilbert; Stephanie R. Harstad; Victor G. Young Jr.; Jeffrey R. Long; John E. Ellis (2017). "Ta(CNDipp)6: An Isocyanide Analogue of Hexacarbonyltantalum(0)". Angewandte Chemie International Edition. 56 (35): 10577–10581. doi:10.1002/anie.201706323. PMID 28697283. Additionally, Ta(0) has also been previously reported in Ta(bipy)₃, but this has been proven to contain Ta(V).
Wang, Guanjun; Zhou, Mingfei; Goettel, James T.; Schrobilgen, Gary G.; Su, Jing; Li, Jun; Schlöder, Tobias; Riedel, Sebastian (2014). "Identification of an iridium-containing compound with a formal oxidation state of IX". Nature. 514 (7523): 475–477. Bibcode:2014Natur.514..475W. doi:10.1038/nature13795. PMID 25341786. S2CID 4463905.
Mézaille, Nicolas; Avarvari, Narcis; Maigrot, Nicole; Ricard, Louis; Mathey, François; Le Floch, Pascal; Cataldo, Laurent; Berclaz, Théo; Geoffroy, Michel (1999). "Gold(I) and Gold(0) Complexes of Phosphinine-Based Macrocycles". Angewandte Chemie International Edition. 38 (21): 3194–3197. doi:10.1002/(SICI)1521-3773(19991102)38:21<3194::AID-ANIE3194>3.0.CO;2-O. PMID 10556900.
Dong, Z.-C.; Corbett, J. D. (1996). "Na₂₃K₉Tl_15.3: An Unusual Zintl Compound Containing Apparent Tl₅⁷⁻, Tl₄⁸⁻, Tl₃⁷⁻, and Tl⁵⁻ Anions". Inorganic Chemistry. 35 (11): 3107–12. doi:10.1021/ic960014z. PMID 11666505.
Pb(0) carbonyls have been observered in reaction between lead atoms and carbon monoxide; see Ling, Jiang; Qiang, Xu (2005). "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. 122 (3): 34505. Bibcode:2005JChPh.122c4505J. doi:10.1063/1.1834915. ISSN 0021-9606. PMID 15740207.
Bi(0) state exists in a N-heterocyclic carbene complex of dibismuthene; see Deka, Rajesh; Orthaber, Andreas (May 9, 2022). "Carbene chemistry of arsenic, antimony, and bismuth: origin, evolution and future prospects". Royal Society of Chemistry. 51 (22): 8540–8556. doi:10.1039/d2dt00755j. PMID 35578901. S2CID 248675805.
Th(-I) and U(-I) have been detected in the gas phase as octacarbonyl anions; see Chaoxian, Chi; Sudip, Pan; Jiaye, Jin; Luyan, Meng; Mingbiao, Luo; Lili, Zhao; Mingfei, Zhou; Gernot, Frenking (2019). "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. 25 (50): 11772–11784. doi:10.1002/chem.201902625. ISSN 0947-6539. PMC 6772027. PMID 31276242.
Np(II), (III) and (IV) have been observed, see Dutkiewicz, Michał S.; Apostolidis, Christos; Walter, Olaf; Arnold, Polly L (2017). "Reduction chemistry of neptunium cyclopentadienide complexes: from structure to understanding". Chem. Sci. 8 (4): 2553–2561. doi:10.1039/C7SC00034K. PMC 5431675. PMID 28553487.
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. (2017). "Identification of the Formal +2 Oxidation State of Plutonium: Synthesis and Characterization of {Pu^II[C₅H₃(SiMe₃)₂]₃}⁻". J. Am. Chem. Soc. 139 (11): 3970–3973. doi:10.1021/jacs.7b00706. PMID 28235179.
Preparation of plutonium(VIII) compounds has been claimed, see Zaitsevskii, Andréi; Mosyagin, Nikolai S.; Titov, Anatoly V.; Kiselev, Yuri M. (July 21, 2013). "Relativistic density functional theory modeling of plutonium and americium higher oxide molecules". The Journal of Chemical Physics. 139 (3): 034307. Bibcode:2013JChPh.139c4307Z. doi:10.1063/1.4813284. PMID 23883027. and Kiselev, Yu. M.; Nikonov, M. V.; Dolzhenko, V. D.; Ermilov, A. Yu.; Tananaev, I. G.; Myasoedov, B. F. (January 17, 2014). "On existence and properties of plutonium(VIII) derivatives". Radiochimica Acta. 102 (3): 227–237. doi:10.1515/ract-2014-2146. S2CID 100915090. But their existence has been partially disproven, see Fedosseev, Alexander M.; Bessonov, Alexi A.; Shilov, Vladimir P. (September 5, 2022). "Is octavalent plutonium really formed during oxidation in alkaline aqueous solutions?". Radiochimica Acta. 110 (12): 955–959. doi:10.1515/ract-2022-0056.
Kovács, Attila; Dau, Phuong D.; Marçalo, Joaquim; Gibson, John K. (2018). "Pentavalent Curium, Berkelium, and Californium in Nitrate Complexes: Extending Actinide Chemistry and Oxidation States". Inorg. Chem. 57 (15). American Chemical Society: 9453–9467. doi:10.1021/acs.inorgchem.8b01450. OSTI 1631597. PMID 30040397. S2CID 51717837.
Pauling, L. (1948). "The modern theory of valency". J. Chem. Soc. 1948: 1461–1467. doi:10.1039/JR9480001461. PMID 18893624. Archived from the original on 2021-12-07. Retrieved 2021-11-22.

ncbi.nlm.nih.gov

Karen, Pavel (2015). "Oxidation State, A Long-Standing Issue!". Angewandte Chemie International Edition. 54 (16): 4716–4726. doi:10.1002/anie.201407561. PMC 4506524. PMID 25757151.
Jackson, Ross A.; Evans, Nicholas J.; Babula, Dawid J.; Horsley Downie, Thomas M.; Charman, Rex S. C.; Neale, Samuel E.; Mahon, Mary F.; Liptrot, David J. (2025-01-28). "Nucleophilicity at copper(-I) in a compound with a Cu–Mg bond". Nature Communications. 16 (1): 1101. Bibcode:2025NatCo..16.1101J. doi:10.1038/s41467-025-56544-z. ISSN 2041-1723. PMC 11775243. PMID 39875432.
Rh(VII) is known in the RhO₃⁺ cation, see Da Silva Santos, Mayara; Stüker, Tony; Flach, Max; Ablyasova, Olesya S.; Timm, Martin; von Issendorff, Bernd; Hirsch, Konstantin; Zamudio-Bayer, Vicente; Riedel, Sebastian; Lau, J. Tobias (2022). "The Highest Oxidation State of Rhodium: Rhodium(VII) in [RhO3]+". Angew. Chem. Int. Ed. 61 (38): e202207688. doi:10.1002/anie.202207688. PMC 9544489. PMID 35818987.
Pd(I) is known in [Pd₂]²⁺ compounds; see Christoph Fricke; Theresa Sperger; Marvin Mendel; Franziska Schoenebeck (2020). "Catalysis with Palladium(I) Dimers". Angewandte Chemie International Edition. 60 (7): 3355–3366. doi:10.1002/anie.202011825. PMC 7898807. PMID 33058375.
Pd(III) has been observed; see Powers, D. C.; Ritter, T. (2011). "Palladium(III) in Synthesis and Catalysis" (PDF). Higher Oxidation State Organopalladium and Platinum Chemistry. Topics in Organometallic Chemistry. Vol. 35. pp. 129–156. Bibcode:2011hoso.book..129P. doi:10.1007/978-3-642-17429-2_6. ISBN 978-3-642-17428-5. PMC 3066514. PMID 21461129. Archived from the original (PDF) on June 12, 2013.
Palladium(V) has been identified in complexes with organosilicon compounds containing pentacoordinate palladium; see Shimada, Shigeru; Li, Yong-Hua; Choe, Yoong-Kee; Tanaka, Masato; Bao, Ming; Uchimaru, Tadafumi (2007). "Multinuclear palladium compounds containing palladium centers ligated by five silicon atoms". Proceedings of the National Academy of Sciences. 104 (19): 7758–7763. Bibcode:2007PNAS..104.7758S. doi:10.1073/pnas.0700450104. PMC 1876520. PMID 17470819.
La(I), Pr(I), Tb(I), Tm(I), and Yb(I) have been observed in MB₈⁻ clusters; see Li, Wan-Lu; Chen, Teng-Teng; Chen, Wei-Jia; Li, Jun; Wang, Lai-Sheng (2021). "Monovalent lanthanide(I) in borozene complexes". Nature Communications. 12 (1): 6467. Bibcode:2021NatCo..12.6467L. doi:10.1038/s41467-021-26785-9. PMC 8578558. PMID 34753931.
Th(-I) and U(-I) have been detected in the gas phase as octacarbonyl anions; see Chaoxian, Chi; Sudip, Pan; Jiaye, Jin; Luyan, Meng; Mingbiao, Luo; Lili, Zhao; Mingfei, Zhou; Gernot, Frenking (2019). "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. 25 (50): 11772–11784. doi:10.1002/chem.201902625. ISSN 0947-6539. PMC 6772027. PMID 31276242.
Np(II), (III) and (IV) have been observed, see Dutkiewicz, Michał S.; Apostolidis, Christos; Walter, Olaf; Arnold, Polly L (2017). "Reduction chemistry of neptunium cyclopentadienide complexes: from structure to understanding". Chem. Sci. 8 (4): 2553–2561. doi:10.1039/C7SC00034K. PMC 5431675. PMID 28553487.

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"HSn". NIST Chemistry WebBook. National Institute of Standards and Technology. Retrieved 23 January 2013.
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osti.gov

Unstable carbonyl of Al(0) has been detected in reaction of Al₂(CH₃)₆ with carbon monoxide; see Sanchez, Ramiro; Arrington, Caleb; Arrington Jr., C. A. (December 1, 1989). "Reaction of trimethylaluminum with carbon monoxide in low-temperature matrixes". American Chemical Society. 111 (25): 9110-9111. Bibcode:1989JAChS.111.9110S. doi:10.1021/ja00207a023. OSTI 6973516.
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researchgate.net

Unstable In(0) carbonyls and clusters have been detected, see [2], p. 6.
Sn(−3) has been observed in [Sn₂]⁶⁻, e.g. in (Ba₂)⁴⁺(Mg₄)⁸⁺Sn⁴⁻(Sn₂)⁶⁻Sn²⁻ (with square (Sn²⁻)_n sheets), see Papoian, Garegin A.; Hoffmann, Roald (2000). "Hypervalent Bonding in One, Two, and Three Dimensions: Extending the Zintl–Klemm Concept to Nonclassical Electron-Rich Networks". Angew. Chem. Int. Ed. 2000 (39): 2408–2448. doi:10.1002/1521-3773(20000717)39:14<2408::aid-anie2408>3.0.co;2-u. PMID 10941096. Retrieved 2015-02-23.

science.org

Boronski, Josef T.; Crumpton, Agamemnon E.; Wales, Lewis L.; Aldridge, Simon (2023-06-16). "Diberyllocene, a stable compound of Be(I) with a Be–Be bond". Science. 380 (6650): 1147–1149. Bibcode:2023Sci...380.1147B. doi:10.1126/science.adh4419. ISSN 0036-8075. PMID 37319227. S2CID 259166086.

sciencedirect.com

Ga(0) is known in gallium monoiodide; see Widdifield, Cory M.; Jurca, Titel; Richeson, Darrin S.; Bryce, David L. (2012-03-16). "Using 69/71Ga solid-state NMR and 127I NQR as probes to elucidate the composition of "GaI"". Polyhedron. 35 (1): 96–100. doi:10.1016/j.poly.2012.01.003. ISSN 0277-5387.

scitation.org

aip.scitation.org

Pb(0) carbonyls have been observered in reaction between lead atoms and carbon monoxide; see Ling, Jiang; Qiang, Xu (2005). "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. 122 (3): 34505. Bibcode:2005JChPh.122c4505J. doi:10.1063/1.1834915. ISSN 0021-9606. PMID 15740207.

semanticscholar.org

api.semanticscholar.org

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Anastas Sidiropoulos (2019). "Studies of N-heterocyclic Carbene (NHC) Complexes of the Main Group Elements". p. 39. doi:10.4225/03/5B0F4BDF98F60. S2CID 132399530.
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Bi(0) state exists in a N-heterocyclic carbene complex of dibismuthene; see Deka, Rajesh; Orthaber, Andreas (May 9, 2022). "Carbene chemistry of arsenic, antimony, and bismuth: origin, evolution and future prospects". Royal Society of Chemistry. 51 (22): 8540–8556. doi:10.1039/d2dt00755j. PMID 35578901. S2CID 248675805.
Preparation of plutonium(VIII) compounds has been claimed, see Zaitsevskii, Andréi; Mosyagin, Nikolai S.; Titov, Anatoly V.; Kiselev, Yuri M. (July 21, 2013). "Relativistic density functional theory modeling of plutonium and americium higher oxide molecules". The Journal of Chemical Physics. 139 (3): 034307. Bibcode:2013JChPh.139c4307Z. doi:10.1063/1.4813284. PMID 23883027. and Kiselev, Yu. M.; Nikonov, M. V.; Dolzhenko, V. D.; Ermilov, A. Yu.; Tananaev, I. G.; Myasoedov, B. F. (January 17, 2014). "On existence and properties of plutonium(VIII) derivatives". Radiochimica Acta. 102 (3): 227–237. doi:10.1515/ract-2014-2146. S2CID 100915090. But their existence has been partially disproven, see Fedosseev, Alexander M.; Bessonov, Alexi A.; Shilov, Vladimir P. (September 5, 2022). "Is octavalent plutonium really formed during oxidation in alkaline aqueous solutions?". Radiochimica Acta. 110 (12): 955–959. doi:10.1515/ract-2022-0056.
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uni-kassel.de

Hofmann, Patrick (1997). Colture. Ein Programm zur interaktiven Visualisierung von Festkörperstrukturen sowie Synthese, Struktur und Eigenschaften von binären und ternären Alkali- und Erdalkalimetallgalliden (PDF) (Thesis) (in German). PhD Thesis, ETH Zurich. p. 72. doi:10.3929/ethz-a-001859893. hdl:20.500.11850/143357. ISBN 978-3728125972.

uwaterloo.ca

bernath.uwaterloo.ca

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web.archive.org

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worldcat.org

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Boronski, Josef T.; Crumpton, Agamemnon E.; Wales, Lewis L.; Aldridge, Simon (2023-06-16). "Diberyllocene, a stable compound of Be(I) with a Be–Be bond". Science. 380 (6650): 1147–1149. Bibcode:2023Sci...380.1147B. doi:10.1126/science.adh4419. ISSN 0036-8075. PMID 37319227. S2CID 259166086.
Tetrazoles contain a pair of double-bonded nitrogen atoms with oxidation state 0 in the ring. A Synthesis of the parent 1H-tetrazole, CH₂N₄ (two atoms N(0)) is given in Henry, Ronald A.; Finnegan, William G. (1954). "An Improved Procedure for the Deamination of 5-Aminotetrazole". Journal of the American Chemical Society. 76 (1): 290–291. Bibcode:1954JAChS..76..290H. doi:10.1021/ja01630a086. ISSN 0002-7863.
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Ga(0) is known in gallium monoiodide; see Widdifield, Cory M.; Jurca, Titel; Richeson, Darrin S.; Bryce, David L. (2012-03-16). "Using 69/71Ga solid-state NMR and 127I NQR as probes to elucidate the composition of "GaI"". Polyhedron. 35 (1): 96–100. doi:10.1016/j.poly.2012.01.003. ISSN 0277-5387.
A Se(0) atom has been identified using DFT in [ReOSe(2-pySe)₃]; see Cargnelutti, Roberta; Lang, Ernesto S.; Piquini, Paulo; Abram, Ulrich (2014). "Synthesis and structure of [ReOSe(2-Se-py)3]: A rhenium(V) complex with selenium(0) as a ligand". Inorganic Chemistry Communications. 45: 48–50. doi:10.1016/j.inoche.2014.04.003. ISSN 1387-7003.
Ma, Wen; Herbert, F. William; Senanayake, Sanjaya D.; Yildiz, Bilge (2015-03-09). "Non-equilibrium oxidation states of zirconium during early stages of metal oxidation". Applied Physics Letters. 106 (10). Bibcode:2015ApPhL.106j1603M. doi:10.1063/1.4914180. hdl:1721.1/104888. ISSN 0003-6951.
Brauer, G.; Haucke, W. (1936-06-01). "Kristallstruktur der intermetallischen Phasen MgAu und MgHg". Zeitschrift für Physikalische Chemie. 33B (1): 304–310. doi:10.1515/zpch-1936-3327. ISSN 2196-7156. MgHg then lends itself to an oxidation state of +2 for Mg and -2 for Hg because it consists entirely of these polar bonds with no evidence of electron unpairing. (translated)
Pb(0) carbonyls have been observered in reaction between lead atoms and carbon monoxide; see Ling, Jiang; Qiang, Xu (2005). "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. 122 (3): 34505. Bibcode:2005JChPh.122c4505J. doi:10.1063/1.1834915. ISSN 0021-9606. PMID 15740207.
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yale.edu

chem125-oyc.webspace.yale.edu

"Lavoisier on Elements". Chem125-oyc.webspace.yale.edu. Archived from the original on 13 June 2020. Retrieved 14 July 2018.

zenodo.org

Langmuir, Irving (1919). "The arrangement of electrons in atoms and molecules". J. Am. Chem. Soc. 41 (6): 868–934. Bibcode:1919JAChS..41..868L. doi:10.1021/ja02227a002. Archived from the original on 2019-06-21. Retrieved 2019-07-01.
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znaturforsch.com

Ga(−3) has been observed in LaGa, see Dürr, Ines; Bauer, Britta; Röhr, Caroline (2011). "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. (in German). 66b: 1107–1121.