文摘
1-Alkynyl-dimethyl(triorganophosphine)gold(III) complexes of the type cis-Me2(Ph3P)AuaaaCCaaaR with R=H, Me, Ph (1aaa3) have been prepared from the cis-Me2(Ph3P)AuX (X=Cl, I) complexes and lithium alkynyls. The crystal structures of 1 and 2 have been determined together with those of the reference compounds cis-Me2(Ph3P)AuX (X=Cl, I) and cis-Me2(Me3P)AuI. The molecules have a standard square planar geometry and are not associated into oligomers. Due to the different hybridization of the carbon orbitals, the AuaaaC(CR) bonds are found significantly shorter than the AuaaaCH3 bonds. Compounds 1aaa3 are stable colourless, crystalline solids at 20 aaC but decompose on heating with selective (cis) reductive elimination of ethane and formation of the gold(I) alkynyls (Ph3P)AuaaaCCaaaR thus retaining the stronger gold-alkynyl bonds. Two complexes of this type have also been prepared by conventional routes from (R3P)AuX complexes and the crystal structures of (Me3P)AuaaaCCaaaPh and [(p-Tol)3P]AuaaaCCaaaH have been determined. The former with the small Me3P ligand is associated into two different trimers via aurophilic bonding and further aggregated into chains via weak inter-trimer contacts, while the latter is a monomer owing to the steric bulk of the (p-Tol)3P ligand.