Effects of neutral ligands in the reductive carbonylation of nitrobenzene catalysed by Ru3(CO)12 and Rh6(CO)16

Abstract The reductive carbonylation of nitrobenzene to give PhNHCO 2 Me is catalysed by Ru 3 (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 Ru 3− (CO) 10 (μ-DPPM) and Ru 3 (CO) 10 (μ-DPPE) (already known) and Ru 3 (CO) 10 -(μ-DPPP) and a mixture of Ru 3 (CO) 11 (η 1 -DPPP)with [Ru 3 (CO) 11 2 (μ-DPPP) (synthesized in the present work) have also been used as catalysts. Even the systems Rh 6 (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.