Chemistry of di- and tri-metal complexes with bridging carbene or carbyne ligands. Part 1. Synthesis of platinum–chromium, –molybdenum, and –tungsten compounds; crystal structure of [(OC)5W{µ-C(OMe)Ph}Pt(PMe3)2]

Abstract

The compounds [M{C(OMe)Ph}(CO)₅](M = Cr or W) react with [Pt(cod)₂](cod = cyclo-octa-1,5-diene) to give metal—metal-bonded complexes [(OC)₅[graphic omitted]t(cod)]. Ethylene-saturated light petroleum solutions of [Pt(cod)₂], treated with 2 mol of tertiary phosphine, react with the mononuclear metal compounds [M{C(OMe)Ph}(CO)₅](M = Cr, Mo, or W) and [W{C(OMe)Me}(CO)₅] to afford the carbene-bridged dimetal complexes [(OC)₅[graphic omitted]t(PR₃)₂](M = Cr or Mo, PR₃= PMe₃ or PMe₂Ph; M = W, PR₃= PMe₃) and [(OC)₅[graphic omitted]t(PMe₃)₂]. Phosphorus-31, ¹H and ¹³C n.m.r. studies support the structures proposed, and for [(OC)₅[graphic omitted]t(PMe₃)₂] the structure has been confirmed by a single-crystal X-ray diffraction study. Crystals are triclinic, with space group P and Z= 2 in a unit cell of dimensions a= 9.728(5), b= 16.002(13), c= 9.611(6)Åα= 109.86(6), β= 116,34(4), and γ= 83.77(6)°. The structure has been determined by heavy-atom methods from automated diffractometer data for 2.9 ⩽ 2θ⩽ 50° and refined to R 0.049 (R′ 0.048) for 3 735 independent reflections. A tungsten–platinum bond (2.861 (1)Å] is asymmetrically bridged by a C(OMe)Ph group [C–Pt 2.04(1), C–W 2.48(1)Å]. Reaction of the compounds [(OC)₅[graphic omitted]t(PMe₃)₂](M = Cr or W) with trimethylphosphine gives the complexes [(Me₃P)(OC)₄[graphic omitted]t(PMe₃)₂], while the chromium compound with Bu^tNC yields [(Bu^tNC)₂(OC)₃[graphic omitted]t(CNBu^t)(PMe₃)]. The n.m.r. data for these products are discussed.