Reactions of W-2(H)(OR)(7), W-2(OR)(6)(py)(2) and W-4((OCH2C4H7)-C-c)(12) compounds (R=Pr-i, CH(2)Bu(t), (C5H9)-C-c) with azobenzene, 1,2-diphenylhydrazine and 1,1-dimethylhydrazine

The reaction of W-2(H)(OR)(7), W-2(OR)(6)(py)(2) and W-4((OCH2C4H7)-C-c)(12) compounds (R = Pr-i, CH(2)Bu(t), (C5H9)-C-c) in hydrocarbon solvents with azobenzene, 1,2-diphenylhydrazine and 1,2-dimethylhydrazine have been studied. The tetranuclear cluster proved to be inert while W-2(H)(OR)(7) was the most kinetically labile. In all cases where a reaction was observed the dinuclear center was ultimately oxidized with the formation of imido (NR(2-)) or hydrazido (NNR(2)(2-)) ligands being formed. These were isolated as compounds of W(6+) supported by four OR ligands. These products require alkoxide group scrambling and no compound from which OR groups were lost was detected. Studies of the reactions between W,(H)(OR), compounds and hydrazines by low-temperature NMR spectroscopy indicate the initial formation of 1:1 adducts followed by elimination of H-2 and ROH as the hydrazine is activated. The following compounds were isolated and crystallographically characterized by single crystal studies: [W(OPri)(4)NPh](2), [W-3(mu(3)-H)(OPri)(9)(NPh)(py)], [W(OPri)(4)(NPh)(py)] and [W(OPri)(4)(NNMe(2))(py)]. The trinuclear tungsten compound is noteworthy in being a ran, if not the only, example of a 12-electron triangular metal cluster capped by a hydride ligand. In the other structures the W(6+) center is in a distorted octahedral coordination and the imido or hydrazido(2-) ligand is terminal with significant contribution from the resonance form having a W-N triple bond. (C) 1997 Elsevier Science Ltd.