Syntheses, Structures, and Reactions of Di-μ-hydroxo Dinuclear Complexes of Tungsten(IV) and Molybdenum(IV)

The title compounds have been prepared in good yields by reaction of Cp₂MH₂ (M = W or Mo) with Cp₂M(OTs)₂ (OTs = p-CH₃C₆H₄SO₃) in aqueous acetone. The products were investigated by IR, ¹H NMR, and ¹³C NMR spectroscopy as well as by X-ray crystallography. The molecules of the two compounds are isostructural. The structures comprise a planar four-membered ring consisting of alternating M and O atoms. In methanol solution, ¹H NMR chemical shifts for the cyclopentadienyl units of the complexes are significantly deshielded with respect to those for the parent dihydrides. The reactions between these complexes and tertiary phosphines in alcoholic solvents yield novel alkoxo complexes [Cp₂M(PR₃)(R‘O)]⁺(OTs^-) (2) (R = Et, Buⁿ, and Ph; R‘ = Me, Et, Prⁱ, CF₃CH₂, and Ph). The structure of the complex with (R = Buⁿ and R‘ = CF₃CH₂, determined by a single-crystal X-ray diffraction study, exhibits a distorted tetrahedral geometry with Mo−P = 2.540 Å and internal angle CP1−Mo−CP2 (CP is the centroid of the cyclopentadienyl ligand) = 132.8°.