Synthesis and characterization of IPr(Me)-containing silver(I), gold(I) and gold(III) complexes.

The compounds 4,5-dimethyl-N,N'-bis(2,6-diisopropylphenyl)imidazol-2-ylidene silver chloride [AgCl(IPr(Me))] and 4,5-dimethyl-N,N'-bis(2,6-diisopropylphenyl)imidazol-2-ylidene gold(I) chloride [AuCl(IPr(Me))] have been synthesized. The attempted synthesis of the corresponding 4,5-dimethyl-N,N'-bis(2,6-diisopropylphenyl)imidazol-2-ylidene gold(III) chloride by oxidative addition of chlorine gas on allowed for the formation of the expected complex, concomitantly with , resulting from a chlorination of a methyl group situated in the backbone of the NHC (N-heterocyclic carbene). Additionally, the buried volume %V(bur) of the IPr(Me) ligand in [AgCl(IPr(Me))] and [AuCl(IPr(Me))] complexes was calculated and compared to %V(bur) of more classical NHCs. This quantification of the steric hinderance of the IPr(Me) ligand reveals the influence of the substituent modulation in the backbone of NHCs.