The First Complexes of Tetragoldmethane CAu4

Abstract

Treatment of C[B(OMe)2]4 with four equivalents of a (tert-phosphine)gold(I) chloride LAuCl with L = P(c-C6H11)3 or (2-MeC6H4)3P in the presence of CsF in hexamethylphosphoric triamide (HMPT) affords the first complexes of the type (LAu)4C. The product is formed together with salts (LAu)5C+BF4- as the by-product for L = tricyclohexylphosphine, from which it can be separated by fractional crystallisation. With Ph2(2-MeCH4)P only the hexacoordinate species (LAu)6C2+2 BF4- is obtained, while with Ph(2-MeC6H4)2P a mixture of (LAu)6C2+ and (LAu)5C+ salts is generated. The title compounds are stable, colourless solids readily identified by standard analytical and spectroscopic techniques, including 13C NMR of 13C-enriched material.