SUPPORTED TRANSITION METALS AND METAL OXIDES AS CATALYSTS FOR THE METAL CARBONYL SUBSTITUTION REACTION

Article abstract of DOI:10.1016/0022-328X(87)87126-7

A range of supported transition metals and metal oxides have been investigated as catalysts for the metal carbonyl substitution reaction M-CO+L->M-L+CO (L=isocyanide (RNC), Group V donor ligand).The use of model substitution reactions reveals the metals Pd, Pt, Ru and Rh and the oxides PdO and PtO2 to be efficient catalysts for substitution reactions of mono-, di- and polynuclear metal carbonyl complexes, and, while there are observable effects which relate to the nature of the catalyst support, catalyst dispersion, catalyst activation and catalyst poisoning, the generally observed orders of activity are Pd>Pt>Ru>Rh and PdO>PtO2.The radical traps hydroquinone and galvinoxyl have an inhibiting effect on catalyst, while light has a mild promotional effect.These observations are consistent with a catalytic mechanism similar to that observed for <<(η⁵-C5H5)Fe(CO)2>2>, namely a radical non-chain process.The metal and metal oxides display considerable potential for the synthesis of substituted metal carbonyl complexes including 5-n(CNR)_n> (n=1-5), 6-n(CNR)_n> (M=Cr, Mo, W; n=1-3), (M3(C)_12-n(CNR)_n> (M=Ru,(n=1-3; M=Os, n=1-4), and (L=Group V donor ligand).Certain catalyst supports (zeolites, activated carbon) have themselves been found to possess mild activity for the catalytic carbonyl substitution reaction.