Stabilisation of vinylic intermediate in the addition, cylisation, and oligomerisation reactions of alkynes by co-ordination to molybdenum and tungsten. The crystal and molecular structure of [W(SC6H4Me-p){η2-C(CF3)·C(CF3)PEt3}(η2-CF3CCCF3)(η-C5H5)] and [WCl{η2-C(CF3)·C(CF3)CNBut}(η2-CF3CCCF3)(η-C5H5)]

Abstract

Nucleophilic atteck of phosphines, phosphites, and t-butyl isocyanide (L) on the bis-hexafluorobut-2-yne complexes [WBr₂CO(CF₃CCCF₃)₂] and [MX(CF₃CCCF₃)₂(η-C₅H₅)](M = Mo, W; X = Cl, SC₆F₅: M = W; X = SC₆H₆Me-p) occurs at an acetylenic carbon atom to give 1:1 adducts shown by X-ray deffraction studies to contain a metal-stabilised 1–3 dipolar vinyl ligand LC(CF₃)·C(CF₃) co-ordinated in an η² manner to the metal centre.