Synthesis, Structure, and Bonding of the Cation [{(C₆H₅)₃PAu}₅C]⊕

An AuC bond order of 0.8 characterizes the pentaauriomethyl cation 1, so that the central carbon atom cannot be regarded as hypervalent. Compound 1 is formed from CH2[B(OMe)2]2 and [Ph3PAuCl] in the presence of CsF as BF salt in 84% yield. The trigonal-bipyramidal coordination of the carbon center is slightly distorted. This may be due to a reduction in energy upon lowering the symmetry or to ligand–ligand repulsion or packing effects.