Acceptor substituted N-heterocyclic carbenes and their Rh(I) complexes:: Synthesis, structure and properties

Rhodium(I) complexes of acceptor substituted N-heterocyclic carbenes were obtained either by transmetalation from the corresponding Ag(I) complexes or by thermal decomposition of corresponding pentafluorobenzene carbene adducts. All complexes were fully characterized by means of NMR- and mass spectroscopy. Compounds 5, 6, 7 and 11 were although characterized by single-crystal X-ray analysis. The relative sigma-donor/pi-acceptor strength of the NHC ligands was determined by means of IR spectroscopy. Dimerisation behaviour of Rh carbonyl complexes was studied. (C) 2008 Elsevier B.V. All rights reserved.