Chemistry of polynuclear metal complexes with bridging carbene or carbyne ligands. Part 93. Synthesis of heteropolynuclear metal compounds with chains of seven to eleven metal atoms; crystal structure of [Mo2W3Pt6(µ3-CMe)3(µ3-CC6H4Me-4)2(CO)10(PMe2Ph)4(η-C5H5)5]

Abstract

Addition of [Pt(cod)₂](cod = cyclo-octa-1,5-diene) in ethylene-saturated thf (tetrahydrofuran) to the compound [Mo₂WPt₃(µ-CMe)(µ₃-CC₆H₄Me-4)₂(CO)₆(cod)(η-C₅H₅)₃] in the same solvent affords the heptanuclear metal complex [Mo₂WPt₄(µ₃-CMe)(µ₃-CC₆H₄Me-4)₂(CO)₆(cod)₂(η-C₅H₅)₃]. The cod ligands in the latter species were displaced upon treatment with the reagents [W(CR)(CO)₂(η-C₅H₅)](R = C₆H₄Me-4 or Me) to give the nonanuclear metal compounds [Mo₂W₃Pt₄(µ-CC₆H₄Me-4)₂(µ₃-CMe)(µ₃-CC₆H₄Me-4)₂(CO)₁₀(η-C₅H₅)₅] and [Mo₂W₃Pt₄(µ-CMe)2(µ₃-CMe)(µ₃-CC₆H₄Me-4)₂(CO)₁₀(η-C₅H₅)₅], respectively. Complexes containing chains of ten or eleven metal atoms have also been prepared. Thus [Mo₂W₃Pt₄(µ-CC₆H₄Me-4)₂(µ₃-CMe)(µ₃-CC₆H₄Me-4)₂(CO)₁₀(η-C₅H₅)₅] reacts with an excess of [Pt(cod)₂] to yield a mixture of [Mo₂W₃Pt₅(µ-CC₆H₄Me-4)(µ₃-CMe)(µ₃-CC₆H₄Me-4)₃(CO)₁₀(cod)(η-C₅H₅)₅], and [Mo₂W₃Pt₆(µ₃-CMe)(µ₃-CC₆H₄Me-4)₄(CO)₁₀(cod)₂(η-C₅H₅)₅]; and [Mo₂W₃Pt₆(µ₃-CMe)₃(µ₃-CC₆H₄Me-4),(CO)₁₀(cod)₂(η-C₅H₅)₅] is obtained by treating [Mo₂W₃Pt₄(µ-CMe)₂(µ₃-CMe)(µ₃-CC₆H₄Me-4)₂(CO)₁₀(η-C₅H₅)₅] with an excess of [Pt(cod)₂]. Displacement of the cod ligands from [Mo₂W₃Pt₆(µ₃-CMe)₃(µ₃-CC₆H₄Me-4)₂(CO)₁₀(cod)₂(η-C₅H₅)₅] by PMe₂Ph yields the complex [Mo₂W₃Pt₆(µ₃-CMe)₃(µ₃-CC₆H₄Me-4)₂(CO)₁₀(PMe₂Ph)₄(η-C₅H₅)₅], structurally characterised by an X-ray diffraction study. The latter established that the spine of the molecule consisted of eleven metal atoms arranged in the sequence PtWPtMoPtMoPtWPtWPt. Each PtMPt (M = Mo or W) triangle (mean distances: Pt–W 2.751, Pt–Mo 2.745, and Pt ⋯ Pt 3.040 Å) is capped by an alkylidyne fragment (mean distances: µ₃-C–Pt 2.05, µ₃-C–W 2.04, and µ₃-C–Mo 1.98 Å), and the terminal platinum atoms are each ligated by two PMe₂Ph groups.