Preparation of Remote NHC Complexes of Rhodium(I) and Gold(I) by Ligand Transfer

The rNHC complexes (5-butyl-1,2-dimethylpyridin-4(1H)-ylidene)Cr(CO)(5) (1), as well as the novel compounds (1,2-dimethyl-5-phenylpyridin-4(1H)-ylidene)M(CO)(5) (2, M = Cr; 3, M = W) and (1-methylpyridin-4(1H)-ylidene)Cr(CO)(5) (7) were prepared from Fischer carbene complexes. Reaction of 1 with [Rh-2(mu-Cl)(2)(CO)(4)] then afforded the first rNHC Rh-I complex, 4. Transfer of the ligand in 2 to Ph3PAu+ afforded the cationic rNHC gold complex, 5 and reaction of 3 and 7 with [AuCl(tht)] gave the neutral rNHC-AuCl complexes 6 and 8. The compounds were characterised by IR and multinuclear NMR spectroscopy as well as mass spectrometry. The crystal and molecular structures of the remote pyridinylidene complexes 3, 4, 5, 6 and 8 were determined by single-crystal X-ray diffraction. ((c) Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)