“Pincer” N-heterocyclic carbene complexes of rhodium functionalised with pyridyl and bipyridyl donors

The “pincer”-type carbene complexes Rh(C–N–C)Cl and Rh(C–N–N)Cl [C–N–C = 3,3′-diaryl-1,1′-pyridine-2,6-diylbis(imidazol-2-ylidene), C–N–N = 1-aryl-3-(2,2′-bipyridin-6-yl)imidazol-2-ylidene] have been prepared and characterised by spectroscopic and diffraction methods. They bind CO to give cationic complexes but are inert to H2. Both oxidatively add CH2Cl2 to give octahedral RhIII complexes. Theoretical calculations provide insight into the bonding of the Rh(C–N–C)Cl and Rh(C–N–N)Cl complexes.