Reaction of polynuclear acetylide clusters. Synthesis of pentanuclear heterometallic clusters by addition of [M(CO)3(CCPh)(η-C5H5)] to [MOs3(CO)11(CCPh)(η-C5H5)](M = Mo or W). Crystal structures of [Mo2Os3(CO)11(CCPhCCPh)(η-C5H5)2]·2H2O and [MoWOs3(CO)8(µ4-C)-(µ3-CPh)(CCPh)(η-C5H5)2]·CH2Cl2

Abstract

Both the cluster acetylide complexes [MOs₃(CO)₁₁(CCPh)(η-C₅H₅)][M = Mo, (1); or W, (2)] react with [Mo(CO)₃(CCPh)(η-C₅H₅)] to give in low yield planar pentanuclear complexes [MMoOs₃(CO)₁₁(CCPhCCPh)(η-C₅H₅)₂][M = Mo, (3); or W, (4)] which contain a C₄ hydrocarbon fragment derived from head-to-tail coupling between the two acetylide fragments. The C₄ chain of these complexes also undergoes twisting in solution, indicated by variable-temperature ¹H n.m.r. studies. Reaction of complex (1) with [W(CO)₃(CCPh)(η-C₅H₅)] does not produce the coupling product but induces C–C bond scission of [W(CO)₃(CCPh)(η-C₅H₅)] giving a novel carbide–alkylidyne complex [MoWOs₃(CO)₈(µ₄-C)(µ₃-CPh)(CCPh)(η-C₅H₅)₂](5) in low yield. The structures of complexes (3) and (5) have been determined by single-crystal X-ray diffraction studies. Crystal data for (3): space group P2₁/n, a= 9.583(3), b= 25.175(10), c= 16.300(7)Å, β= 91.26(3)°, Z= 4, R= 0.051, and R′= 0.053. Crystal data for (5): space group P, a= 10.072(6), b= 13.217(3), c= 14.800(3)Å, α= 95.41(2), β= 93.17(4), γ= 109.14(4)°, Z= 2, R= 0.056, and R′= 0.062.