Catalytic hydrogenation of Cdouble bond; length as m-dashO and Cdouble bond; length as m-dashN 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)](BArF4) (1a: M = Rh; 1b: M = Ir; Dmp = 2,6-(mesityl)2C6H3, ArF = 3,5-(CF3)2C6H3), catalyzed the hydrogenation of benzaldehyde, N-benzylideneaniline, and cyclohexanone, under 1 atm of H2 at low temperatures. In these catalytic reactions, the M–H/S–H complexes [Cp∗M(PMe3)(H)(HSDmp)](BArF4) (2a: M = Rh; 2b: M = Ir) generated via H2 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 H2 atmosphere.