Honeychuck, R. V.; Hersh, W. H. Coordination of “Noncoordinating” Anions: Synthesis, Characterization, and X-ray Crystal Structures of Fluorine-Bridged [SbF6]−, [BF4]−, and [PF6]− Adducts of [R3P(CO)3(NO)W]+. An Unconventional Order of Anion Donor Strength. Inorganic Chemistry. 1989, 28 (14): 2869–2886. doi:10.1021/ic00313a034.
M. Brookhart, B. Grant, A. F. Volpe, Jr. [(3,5-(CF3)2C6H3)4B]-[H(OEt2)2]+: a convenient reagent for generation and stabilization of cationic, highly electrophilic organometallic complexes. Organometallics. 1992, 11: 3920–3922. doi:10.1021/om00059a071.
Kim, K.-C.; Reed, C. A.; Elliott, D. W.; Mueller, L. J.; Tham, F.; Lin, L.; Lambert, J. B. Crystallographic Evidence for a Free Silylium Ion. Science. 2002, 297 (5582): 825–827. PMID 12161650. doi:10.1126/science.1073540.
Kim, K.-C.; Reed, C. A.; Elliott, D. W.; Mueller, L. J.; Tham, F.; Lin, L.; Lambert, J. B. Crystallographic Evidence for a Free Silylium Ion. Science. 2002, 297 (5582): 825–827. PMID 12161650. doi:10.1126/science.1073540.