Indenyl- and Fluorenyl-Functionalized N-Heterocyclic Carbene Complexes of Rhodium and Iridium - Synthetic, Structural and Catalytic Studies

Rhodium. and iridium. complexes with N-heterocyclic carbenes (NHC) functionalized with neutral or anionic indenyl and fluorenyl groups are reported. In the complexes the ligands adopt monodentate, bidentate or bridging bonding modes with the NHC group sigma-bonded and the fluorenyl or indenyl functionalities either dangling or coordinated to the metal with various hapticities (eta(1), eta(3) and eta(5)). Metallation of the C-H bond of the alkylene linker in the ligand has also been observed. Catalytic studies on the bidentate Rh-I complex 6 show that it is weakly active for the hydroformylation of 1-octene with poor linear selectivity, but it shows slightly lower activity than the standard Monsanto system for the carbonylation of methanol. ((c) Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)