Bimetallic clusters of the general formula [PPN]2[MRh4(CO)15] (M = Fe, Ru, or Os; PPN+ = (PPh3)2N+) are active catalysts in the presence of methanol for the carbonylation of nitrobenzene to methyl phenylcarbamate. The clusters are active even without co-catalyst, but the addition of bipy (2,2'-bipyridine) greatly enhances both rates and selectivities. In the absence of methanol the conversion was much lower, with a low selectivity in phenyl isocyanate. Interchanging Fe, Ru, and Os has a negligible effect on the activity and a moderate effect on the selectivity, with ruthenium being best. However, the monometallic rhodium cluster [Rh5(CO)15]- proved to be both more active and selective, and the monomer [Rh(CO)4]- was found to be even better. This last catalytic system has been optimized with respect to temperature, CO pressure and the bipy/Rh ratio. The influence of solvent was also examined.
|Titolo:||[RH(CO)4]-, [RH5(CO)15]-, AND BIMETALLIC CLUSTERS AS CATALYSTS FOR THE CARBONYLATION OF NITROBENZENE TO METHYL PHENYLCARBAMATE|
RAGAINI, FABIO ATTILIO CIRILLO (Primo)
CENINI, SERGIO (Secondo)
|Settore Scientifico Disciplinare:||Settore CHIM/03 - Chimica Generale e Inorganica|
|Data di pubblicazione:||1992|
|Digital Object Identifier (DOI):||10.1016/0022-328X(92)83101-M|
|Appare nelle tipologie:||01 - Articolo su periodico|