ON CARBOXYLATE AS A LEAVING GROUP AT THE ACTIVE-SITE OF MO NITROGENASE - ELECTROCHEMICAL REACTIONS OF SOME MO AND W CARBOXYLATES, FORMATIONOF MONO-HYDRIDES, DI-HYDRIDES AND TRI-HYDRIDES AND THE DETECTION OF AN MOH2(N2) INTERMEDIATE

A carboxylate ligand can function as a leaving group at a reduced moly bdenum dihydride centre and this exposes a site at which dinitrogen or other small molecules can bind; dihydrogen loss occurs after substrat e binding; protic attack intercepts carboxylate loss affording a trihy dride intermediate which can partake in a hydrogen evolution cycle: it is suggested that carboxylate loss from the reduced Mo centre of nitr ogenase might similarly lead to substrate binding and thence obligator y evolution of H-2.