Catalytic reduction of hydrazine to ammonia by a high-oxidation state molybdenum complex

[MoO2(acac)(2)] (acac=acetylacetonate) promotes the disproportionation of hydrazine in THF Solutions. The active catalytic species. [(MoO2)-O-VI](2+), are produced according to the reaction: [MoO2(C5H7O2)(2)] + 2N(2)H(4) --> [MoO2](2+) + 2C(5)H(8)N(2) + 2OH(-) + 2H(2)O. The main product of the reduction of hydrazine is ammonia while 3,5-dimethylpyrazole (C5H8N2) was isolated as a side-product. A catalytic cycle was proposed and the probable reaction intermediate is a hydrazido-complex, [Mo-IV=NNH2(OH2)(2)](2+). The intermediate Species, [(MoO2NH3)-O-VI](2+) reacts with hydroxide ion leading to the complex cis-[(MoO2)-O-VI(OH)(2)(NH3)], which was isolated and characterized. (C) 2008 Elsevier B.V. All rights reserved.