Dinuclear Pentacarbonyl Tungsten Complex Bridged by Bis (3,5-dimethylpyrazol-1-yl) methane

A new bis (pyrazol-1-yl) methane ligand, [Ph2 (HO) CCH (3,5-Me2Pz)2, Pz= pyrazole] (1), with a bulky substituent on the methine carbon atom has been successfully synthesized by the reaction of bis(3,5-dimethylpyrazol-1-yl) methyllithium with benzophenone. Treatment of this ligand with W(CO)6 under UV-irradiation in THF at room temperature afforded a novel dinuclear complex CH2[3,5-Me2PzW(CO)5]2 (2) with loss of the Ph2CO fragment, which was characterized by IR, 1H NMR spectra and elemental analyses as well as the X-ray single crystal diffraction analysis. This compound crystallizes in the or-thorhombic space group Pbcn, with a = 1.7690(3) nm, b = 1.4460 (3) nm, c = 1.2994 (2) nm, Z = 4, V = 3.3239 (10) nm3, Dc = 1.775 g · m−3, μ = 6.967 mm−1, F (000) = 1672, R1 = 0.0414 and wR2 = 0.0988. Bis(3,5-dimethylpyrazol-l-yl) methane acts as a bridging bidentate ligand in this complex, which links two W(CO)5 fragments. In addition, heating this complex under reflux in 1,2-dimethoxyethane (DME) gives the known chelated mononuclear complex CH2(3,5-Me2Pz)2-W(CO)4 (3).