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

A new bis (pyrazol‐1‐yl) methane ligand, [Ph 2 (HO) CCH (3,5‐Me 2 Pz) 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 CH 2 [3,5‐Me 2 PzW(CO) 5 ] 2 (2) with loss of the Ph 2 CO fragment, which was characterized by IR, 1 H 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) nm 3 , D c = 1.775 g · m −3 , μ = 6.967 mm −1 , F (000) = 1672, R 1 = 0.0414 and wR 2 = 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 CH 2 (3,5‐Me 2 Pz) 2 ‐W(CO) 4 (3).