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).