Chemistry of di- and tri-metal complexes with bridging carbene or carbyne ligands. Part 35. The synthesis and crystal structures of the compounds [N(PPh3)2][W2{µ-C(H)C6H4Me-4}(CO)7(η-C5H5)]·0.5 Et2O and [W{C(H)C6H4Me-4}(SnPh3)(CO)2(η-C5H5)]

Abstract

Treatment of [W(CC₆H₄Me-4)(CO)₂(η-C₅H₅)] with [N(PPh₃)₂][WH(CO)₅] in thf (tetrahydrofuran) affords the salt [N(PPh₃)₂][W₂{µ-C(H)C₆H₄Me-4}(CO)₇(η-C₅H₅)], the structure of which has been established by X-ray diffraction. In the anion, the W–W bond [3.111 (1)Å] is asymmetrically spanned by the C(H)C₆H₄Me-4 group [µ-C–W 2.127(7) and 2.436(8)Å]. One tungsten atom carries five CO groups at octahedral sites around the metal, while the other tungsten atom is ligated by two CO groups and the cyclopentadienyl ring. The latter and the tolyl group are positioned on opposite sides of the µ-CW₂ ring. The reaction between [AsPh₄][WH(CO)₅] and [W(CMe)(CO)₂(η-C₅H₅)] affords [AsPh₄][W₂{C(H)Me}(CO)₇(η-C₅H₅)], and evidence was obtained for the existence in related syntheses of the anions [MW{µ-C(H)C₆H₄Me-4}(CO)₆(L)(η-C₅H₅)]^–[M = Cr, L = CO; M = W, L = P(OMe)₃]. Treatment of [W₂{µ-C(H)C₆H₄Me-4}(CO)₇(η-C₅H₅)] with SnPh₃Cl in thf affords the stable alkylidene complex [W{C(H)C₆H₄Me-4}(SnPh₃)(CO)₂(η-C₅H₅)], the structure of which has been established by a single-crystal X-ray diffraction study. The W–C and W–Sn separations are 2.032(7) and 2.837(1)Å, respectively, with the SnPh₃ and C(H)C₆H₄Me-4 groups in a transoid configuration. The molecule is orientated such that the alkylidene hydrogen substituent is adjacent to the cyclopentadienyl ligand. The n.m.r. data for the new compounds are reported and discussed.