Synthesis of a Square-Planar Rhodium Alkylidene N-Heterocyclic Carbene Complex and its Reactivity Towards Alkenes

Autores: Laura Palacios, Xiaowei Miao, Andrea Di Giuseppe, Simon Pascal, Carmen Cunchillos, Ricardo Castarlenas, Jesús J. Pérez-Torrente, Fernando J. Lahoz, Pierre Dixneuf y Luis A. Oro Ref. revista: Organometallics, 30, 5208-5213 (2011)

The first rhodium alkylidene square-planar complex stabilized by an N-heterocyclic carbene ligand, RhCl-
(dCHPh)(IPr)PPh3 (2; IPr = 1,3-bis(2,6-diisopropylphenyl)imidazol-2-carbene), has been prepared by reaction of RhCl-
(IPr)(PPh3)2 (1) with phenyldiazomethane and its dynamic behavior in solution studied. Treatment of 2 with alkenes
results in the formation of the η2-olefin complexes RhCl(η2-CH2dCHR)(IPr)PPh3 (3, R = H; 4, R = Ph; 5, R = OEt) and
new olefins arising from the coupling of the alkylidene with the alkenes, likely via a metallacyclobutane intermediate.