Chemistry of polynuclear metal complexes with bridging carbene or carbyne ligands. Part 50. Synthesis and crystal structures of the complexes [RuW3(µ-CO)(µ3-η-CO)(µ-CPh)2(µ3-CPh)(CO)2(η-C5H5)3] and [RuW3(µ-CO)(µ3-η-CO){µ-C(Ph)C(O)}(µ-CPh)(µ3-CPh)(CO)(PMePh2)(η-C5H5)3]
Abstract
The zero-valent ruthenium compounds [Ru(η6-C8H10)(cod)](C8H10= cycle-octa-1,3,5-triene, cod = cyclo-octa-1,5-diene) or [Ru(η6-C10H8)(cod)](C10H8= naphthalene) react at room temperature in light petroleum with the alkylidynetungsten complexes [W(![[triple bond, length half m-dash]](https://www.rsc.org/images/entities/char_e007.gif)
CR)(CO)2(η-C5H5)](R = C6H4Me-4 or Ph) to give a chromatographically separable mixture of the cluster compounds [RuW2(µ3-C2R2)(CO)7(η-C5H5)2] and [RuW3(µ-CO)(µ3-η-CO)(µ-CR)2(µ3-CR)(CO)2(η-C5H5)3]. A single-crystal X-ray diffraction study established the molecular structure of the rutheniumtritungsten species containing phenylmethylidyne ligands. The metal-atom core consists of a RuW2 triangle [W–Ru 2.775(2) and 2.847(2), W–W 2.610(l)Å] to which a third tungsten atom is attached via the ruthenium [W–Ru 2.735(2)Å]. The ‘exo- ligated’ tungsten atom carries a terminal CO ligand and a C5H5 group, with the Ru–W bond asymmetrically bridged by CPh and CO groups. The latter is also η-co-ordinated to one of the tungsten atoms in the RuW2 triangle [W–C 2.43(1), W–O 2.05( 1)Å] so that it occupies a triply-bridging site. The tungsten atoms in the triangle are ligated by C5H5 groups, and the ruthenium atom carries a terminal CO ligand. A phenylmethylidyne group symmetrically caps the triangle, and a similar fragment edge-bridges the W–W bond. A carbonyl group bridges the Ru–W edge of the triangle. The compounds [RuW3(µ-CO)(µ3-η-CO)(µ-CR)2(µ3-CR)(CO)2(η-C5H5)3] react with tertiary phosphines to afford complexes [RuW3(µ-CO)(µ3-η-CO){µ-C(R)C(O)}(µ-CR)(µ3-CR)(CO)(PR′3)(η-C5H5)3](R = C6H4Me-4,PR′3= PMe3; R = Ph, PR′3= PMe3 or PMePh2) containing ketenyl groups. An X-ray diffraction study on the complex with R = Ph and PR′3= PMe2Ph established the structure of this class of compound. The core structure of the molecule is remarkably similar to that of its precursor, with the RuW2 triangle ‘spiked’ by a tungsten atom, and with bridging µ-CR, µ3-CR, µ-CO, and µ3-η-CO groups. The important difference is associated with the exo-ligated tungsten which now carries a PMePh2 ligand instead of a terminal CO group, and the W–Ru vector is edge-bridged by a µ-C(Ph)C(O) fragment [W–Ru 2.771 (1), µ-C–Ru 2.19(1), µ-C–W 2.15(1), µ-C(O)–W 2.14(1), µ-C–C 1.39(2)Å]. The i.r. and n.m.r. (1H and 13C-{1H}) spectra of the new compounds are discussed in relation to their structures.
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