Catalytic hydrogenation of C=O and C=N bonds via heterolysis of H2 mediated by metal-sulfur bonds of rhodium and iridium thiolate complexes

Coordinatively unsaturated rhodium and iridium complexes having a bulky thiolate, [Cp*M(PMe3)(SDmp)](BAr4F) (1a: M = Rh; 1b: M = Ir; Dmp = 2,6-(mesityl)(2)C6H3, Ar-F = 3,5-(CF3)(2)C6H3), catalyzed the hydrogenation of benzaldehyde, N-benzylideneaniline, and cyclohexanone, under 1 atm of H-2 at low temperatures. In these catalytic reactions, the M-H/S-H complexes [Cp*M(PMe3)(H)(HSDmp)](BAr4F) (2a: M = Rh; 2b: M = Ir) generated via H-2 heterolysis by 1a or 1b were suggested to transfer both M-H hydride and S-H proton to substrates. The catalytic reactions were terminated by the dissociation of H-SDmp from the metal centers of 2a and 2b that occurs at ambient temperature under H-2 atmosphere. (C) 2009 Elsevier B.V. All rights reserved.