Reactivity of the unsaturated hydride [Mo2(η5-C5H5)2(μ-H)(μ-PCy2)(CO)2] toward 17-and 16-electron metal carbonyl fragments:: Rational synthesis of electron-deficient heterometallic clusters

Reactions of the 30-electron hydride [Mo2Cp2(mu-H)(mu-PCy2)(CO)(2)] (Cp = eta(5)-C5H5) with the 17-electron-fragment precursors [M2Cp2(CO)(n)] (M = Mo, W, n = 6; M = Ru, n = 4) or [Mn-2(CO)(10)] lead to the 46-electron clusters [Mo2MCp3(mu-PCy2)(mu(3)-CO)(CO)(4)] (M = Mo, W), [Mo2RuCp3(mu-PCy2)(mu-CO)(CO)(3)], and [MnMo2Cp2(mu-PCy2)(mu-CO)(2)(CO)(5)]. The structure of the trimolybdenum cluster was confirmed by an X-ray diffraction study and displays two long (ca. 3.1 angstrom) and one short Mo-Mo distance (2.743(1) angstrom). The title unsaturated hydride also proved to be highly reactive toward the appropriate precursors of 16-electron fragments such as M(CO)(5) (M = Cr, Mo, W) and MnCp'(CO)(2) (Cp' = eta(5)-C5H4CH3), then leading to the 46-electron hydride clusters [MMo2Cp2(mu(3)-H)(mu-PCy2)(CO)(7)] (M = Cr, Mo, W) and [MnMo2Cp2Cp'(mu(3)-H)(mu-PCy2)(CO)(4)]. The structures of the compounds having Mo2W and Mo2Mn skeletons were also determined by X-ray diffraction methods, both of them displaying Mo-Mo distances (ca. 2.6 angstrom) somewhat shorter than expected for double Mo=Mo bonds and Mo-M distances longer than the corresponding single-bond lengths. A similar reaction takes place with the 12-electron compound CuCl, to give the hydride [CuMo2ClCp2(mu(3)-H)(mu-PCy2)(CO)(2)]. In contrast, the reaction of the title hydride with [Fe-2(CO)(9)], a precursor of the 16-electron fragment Fe(CO)(4), gives the heterodinuclear complex [FeMo(mu-PCy2)(CO)(6)] (Fe-Mo = 2.931(1) angstrom).