Halogenocarbonyl complexes of gold

Abstract

Carbonyl gold(I) bromide [AuBr(CO)] was obtained in solutions of halogenated hydrocarbons by (a) absorption of CO by [Au₂Br₆] in the presence of cyclohexene as a halogen abstractor, (b) carbonylation of [Au₂Br₆]; (c) carbonylation of AuBr. The compound has been studied by spectroscopic methods in solution, including NMR measurements at variable temperature. Both [AuCl(CO)] and [AuBr(CO)] undergo a rapid exchange process with dissolved CO. The low stability of [AuBr(CO)] with respect to its decomposition to AuBr(s) prevents the isolation of the carbonyl bromide of gold(I). The present findings confirm the trend to lower stability in the sequence Cl > Br > I already established for the carbonylhalogeno derivatives of palladium(II) and platinum(II).