Ligand exchange at a gold(I) carbene complex

摘要

Gold complex [AuCl(NHC)] (NHC=N,N′-dipropylbenzimidazolin-2-ylidene) 1 undergoes facile substitution reactions at the gold(I) center. Treatment of 1 with anionic phenylacetylide or thiophenolate led to the neutral gold complexes 2 and 3, respectively. The cationic gold complexes [Au(NHC)(pyridine)](BF _4) [4]BF_4 and [Au_2(NHC)_2(4,4′- bipyridine)](BF_4)_2 [5](BF_4)_2 were obtained via abstraction of the chloro ligand from 1 and reaction with the appropriate amine. Reaction of 1 with AgBF_4 in the presence of PPh_3 instead of an amine led to an inseparable product mixture of the mixed NHC=PPh_3 complex [6]BF_4, the dicarbene complex [Au(NHC)_2]BF_4, [7]BF_4, and [Au(PPh _3)_2]BF_4, [8]BF_4. Crystals of 2 and [6]BF_4 were obtained, and X-ray diffraction structure analyses revealed that the gold(I) atoms are coordinated in a linear fashion by the NHC and the co-ligand.