CATALYTIC REDUCTION OF CIS-DIMETHYLDIAZENE BY THE [MOFE3S4](3- THE 4-ELECTRON REDUCTION OF A N=N BOND BY A NITROGENASE-RELEVANT CLUSTER ANDIMPLICATIONS FOR THE FUNCTION OF NITROGENASE() CLUSTERS )

The catalytic reduction of cis-dimethyldiazene by the (EtN)(2)[(Cl-4-c at)(CH3CN)MoFe3S4Cl3] cluster (Cl-4-cat = tetrachlorocatecholate) is r eported. Unlike the reduction of cis-dimethyldiazene by the Fe/Mo/S ce nter of nitrogenase, which yields methylamine, ammonia, and methane (t he latter from the reduction of the C-N bond), the reduction of cis-di methyldiazene by the synthetic cluster yields exclusively methylamine. In separate experiments, it was shown that the C-N bond of methylamin e is not reduced by the [MoFe3S4](3+) core, perhaps accounting for the differences observed between the biological and abiological systems. 1,2-Dimethylhydrazine, a possible partially reduced intermediate in th e reduction of cis-dimethyldiazene, was also shown to be reduced to me thylamine. Interaction of methylamine with the Mo atom of the cubane w as confirmed through the synthesis and structural characterization of (Et(4)N)(2)[(Cl-4-cat)(CH3NH2)MoFe3S4Cl3]. Phosphine inhibition studie s strongly suggest that the Mo atom of the [MoFe3S4](3+) core, which h as a Mo coordination environment very similar to that in nitrogenase, is responsible for the binding and activation of cis-dimethyldiazene, The reduction of a N=N bond exclusively at the heterometal site of a n itrogenase-relevant synthetic compound may have implications regarding the function of the nitrogenase Fe/Mo/S center, particularly in the l atter stages of dinitrogen reduction.