Photochemical reaction of W(CO)6 with SnCl4: Part IV - Synthesis of new tungsten alkyne complexes. X-ray crystal structure of [W3(μ3-O) (μ-OH) 2(μ-Cl) 2(O)(η2-PhC≡CPh) 5]

Article abstract of DOI:10.1016/0022-328X(96)06378-4

Reaction of [(CO)₄W(μ-Cl)₃W(SnCl₃)(CO)₃] (1) with alkynes (phenylacetylene, tert-butylacetylene, 3-hexyne and diphenylacetylene at room temperature initially affords the mixture of products [WCl₂(CO)₂(η²-alkyne)₂] (2-5) and [WCl(SnCl₃)(CO)(η₂-alkyne)₂] (2′-5′) in quantitative yields. Tungsten(II) alkyne complexes are very labile in solution and lose CO ligands. After exposure of a mixture of [WCl₂(CO)₂(η²-PhC≡CPh)₂] and [WCl(SnCl₃)(CO)(η²-PhC≡CPh)₂] to moist air the complex [W₃(μ₃-O)(μ-OH)₂(μ-Cl)₂(O)(η²-PhC≡CPh)₅] (6) was isolated and its structure determined by X-ray crystallography. The molecule consists approximately of an isosceles triangle of W atoms joined by triply-bridging oxygen. The longer edge is bridged by two chlorine atoms. The shorter edges are bridged by hydroxy groups. Compound 6 is noteworthy since it is among the first of the trinuclear complexes in which a mixed-valence W^II₂W^IV-(μ₃-O) core has been established. It is also unique in being the first tungsten compound to be isolated containing two different triply-bridged, μ₃-O and μ₃-Cl, ligands.