EFFECTS OF NEUTRAL LIGANDS IN THE REDUCTIVE CARBONYLATION OF NITROBENZENE CATALYZED BY RU3(CO)12 AND RH6(CO)16

The reductive carbonylation of nitrobenzene to give PhNHCO2Me is catalysed by Ru3(CO)12 in toluene-methanol at 170 °C and 60 atm, in the presence of chelating ligands such as diphenylphosphinomethane (DPPM), 1,2-diphenylphosphinoethane (DPPE), 1,3-diphenylphosphinopropane (DPPP), and 2,2'-bipyridine. Preformed complexes such as Ru3- (CO)10(μ-DPPM) and Ru3(CO)10(μ-DPPE) (already known) and Ru3(CO)10-(μ-DPPP) and a mixture of Ru3(CO)11(η1-DPPP)with [Ru3(CO)112(μ-DPPP) (synthesized in the present work) have also been used as catalysts. Even the systems Rh6(CO)16/chelating ligands are good catalysts for the reductive carbonylation of nitrobenzene. However we always observed a partial decomposition of the rhodium catalyst at the end of the catalytic reactions.