Formation and decomposition of alkyl-gold(I) complexes

Abstract

The syntheses of new primary, secondary and tertiary alkyl(triphenylphosphine)gold(I) complexes are described. Isolation of the thermally stable tert-butyl, isopropyl and sec-butylgold(I) complexes is unusual among organotransition metal complexes. All of these alkyl(triphenylphosphine)gold(I) complexes are monomeric in benzene solution. Methyl and primary alkyl derivatives undergo reduction coupling in high yields on thermolysis of the solid or in solution. The more highly branched isopropyl and tert-butyl analogs afford disproportionation products. The decomposition of methyl(triphenylphosphine)gold(I) in decalin follows first-order kinetics and is retarded by added triphenylphosphine. A mechanism for reductive coupling to ethane is proposed, in which a rate-limiting loss of phosphine is followed by a rapid association with an additional methyl(triphenylphosphine)gold(I).