Homogeneous catalytic carbonylation of nitroaromatics Part III. Discovery and in situ high pressure FTIR spectral studies of a novel binuclear ruthenium catalyst

The binuclear ruthenium complex, Ru₂(dmpm)₂(CO)₅, where dmpm=1,2-bis-(dimethylphosphino)methane, was found to catalyze the carbonylation of nitroaromatics in the presence of methanol to give N-arylmethylcarbamates in yields ranging from 47 to 60%. In situ FTIR spectral studies established that an equilibrium mixture of Ru₂(dmpm)₂(CO)₅ and [(μ-H)Ru₂(dmpm)₂(CO)₅]⁺ were present following initial mixing under CO (61 atm). Upon heating to 145 °C a new, as yet unidentified, species was observed. When the nitroaromatic was consumed, the spectrum indicated that the starting complex was reformed.