Alcoholysis of gauche-1,2-(η3-Cp)2W2(NMe2)4: Structural evidence for Wtriple bond; length of mdashW bond cleavage and proton transfer to bound cyclopentadiene

1,2-Cp2W2(NMe2)4 undergoes Wtriple bond; length of mdashW bond scission in the presence of excess aliphatic alcohols ROH where R = Me, Et, Prn giving yellow, crystalline Cp2WH2 and presumably W(OR)6. In reactions with excess CF3CH2OH, two crystalline products are obtained from the pentane wash of the crude product. The first product is formulated as 1,1-W2(η5-Cp)(η3-C5H7)(μ-OCH2CF3)2(OCH2CF3)4, (W–W, 2.705(1) Å avg. for two independent molecules) wherein six equivalents of CF3CH2OH have reacted with the amide precursor. The unusual η3-C5H7 ligand present in this compound arises from the transfer of two protons to one of the Cp rings. The second product is formulated as the complex salt [W(OCH2CF3)6] [H2NMe2][Cp2W(H)x(OCH2CF3)] wherein a H2NMe2 cation bridges the neutral W(OR)6 moiety and the Cp2W(H)x(OCH2CF3) (x = 1 or 2) anion through hydrogen bonding. The formation of the alcoholysis products suggests the importance of oxidative addition in the mechanism of alcoholysis of ditungsten dimethylamides.