Structure and reactivity of dinitrogen rhodium complexes containing n-heterocyclic carbene ligands

The rhodium bis-carbene complex [Rh(IPr)2(N2)Cl] , whereIPr = 1,3-bis(2,6-diisopropylphenyl)imidazol-2-ylidene, hasbeen synthesized and characterized. The complex is a rareexample of a four-coordinate rhodium complex featuring ni-trogen bound end-on. While quite stable as a solid under in-ert atmosphere, in solution the N2 ligand has been found tobe quite labile. This lability has been exploited in the synthe-sis of complexes with the formula [Rh(IPr)2(XY)Cl] , where XY=O2,H2 and CO. Interestingly, the dihydride coordinationleads to oxidation of the metal centre to RhIII, even thoughprevious studies from our lab have shown that Rh remains inthe +1 oxidation state upon coordination of dioxygen.