Rhodium(I), a Carbene-Transfer Transition-Metal Ion and a Synthetic Route to Symmetrical and Asymmetrical Substituted trans-RhCl(CO)(NHC)(NHC) Complexes

Group IX element Rh(I) was shown to be able to transfer N-heterocyclic carbenes. The dimerization process of RhCl(CO)2(NHC) to [RhCl(CO)(NHC)]2, followed by a rearrangement step to trans-RhCl(CO)(NHC)2, is one possible mechanism for the loss of activity of Rh(I) species in various catalytic reactions. Utilizing this methodology symmetrical and asymmetrical trans-RhCl(CO)(NHC)(NHC) complexes were synthesized and characterized.