Synthesis of the hexakis[(triphenylphosphane)gold(I)]methanium(2+) cation from trimethylsilyldiazomethane; crystal structure determination of the tetrafluoroborate salt

A new synthetic route to the bis(tetrafluoroborate) salt of the hexakis[(triphenylphosphane)gold(I)]methanium dication has been opened up through the reaction of trimethylsilyldiazomethane and tris[(triphenylphosphane)gold(I)]oxonium tetrafluoroborate in dichloromethane. Yields are close to 65 % if the reaction is carried out in the presence of triethylamine as a base. The process is a sequence of desilylation, deprotonation and deazotation reactions at the carbon function of the diazomethane, as shown by the detection of intermediates. The crystal structure of the title compound (with three equivalents of crystal dichloromethane) has been determined in a single-crystal X-ray study. The dication has no crystallographically imposed symmetry, but the core is a distorted, carbon-centered octahedron of gold atoms. This result confirms the data from previous structural studies of salts with other anions and interstitial solvents.