Rhodium(iii) complexes containing C4-bound N-heterocyclic carbenes: synthesis, coordination chemistry, and catalytic activity in transfer hydrogenation

Yang, Liangru; Krüger, Anneke; Neels, Antonia; Albrecht, Martin

doi:10.1021/om800110c

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Rhodium(iii) complexes containing C4-bound N-heterocyclic carbenes: synthesis, coordination chemistry, and catalytic activity in transfer hydrogenation

Yang, Liangru Department of Chemistry, University of Fribourg, Switzerland - School of Chemistry and Chemical Engineering, Henan University of Techology, P. R. China.
Krüger, Anneke Department of Chemistry, University of Fribourg, Switzerland
Neels, Antonia Institute of Microtechnology, University of Neuchâtel, Switzerland
Albrecht, Martin Department of Chemistry, University of Fribourg, Switzerland

28.05.2008

Published in:

Organometallics. - 2008, vol. 27, no. 13, p. 3161–3171

English Direct metalation of C2-protected diimidozolium salts with RhCl₃ or [RhCl(cod)]₂ and KI afforded a series of new rhodium(III) complexes with abnormally C4-bound, cis-chelating NHC ligands. The complexes were isolated as dimetallic species containing two (μ²-I)₃-bridged rhodium(III) centers. In the presence of coordinating ligands such as CH₃CN, PPh₃, or dppe, the dimeric structure is readily cleaved and yields monometallic complexes. Crystallographic analysis of representative structures indicates a higher trans influence of abnormally C4-bound carbenes as compared to normal NHCs. The exceptionally strong donor ability of carbenes in such a C4 coordination mode increases the catalytic activity of the rhodium center and allows for efficient transfer hydrogenation of ketones in iPrOH/KOH.

Faculty

Faculté des sciences et de médecine

Department

Département de Chimie

Language