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 A) is capped by an alkylidyne fragment (mean distances: µ3-C–Pt 2.05, µ3-C–W 2.04, and µ3-C–Mo 1.98 A), and the terminal platinum atoms are each ligated by two PMe2Ph groups.