Portal de Periódicos da CAPES

Reactions involving alkynes and tungsten-tungsten triple bonds supported by alkoxide ligands

1987; Elsevier BV; Volume: 6; Issue: 4 Linguagem: Inglês

10.1016/s0277-5387(00)86884-9

1873-3719

Malcolm H. Chisholm, Brian K. Conroy, Bryan W. Eichhorn, Kirsten Folting, David M. Hoffman, John C. Huffman, Nancy S. Marchant,

Synthesis and characterization of novel inorganic/organometallic compounds

W2(OR)6Ln compounds [R = But n = 0; R = Pri or Np (Np = neopentyl), L = py (py = pyridine) or HNMe2, n = 2] react with alkynes (R′C-CR′) under mild conditions (hexane solutions, room temperature or below) to yield a variety of products depending upon the nature of the alkoxide, the alkyne and the mole ratio of the reactants. The products include alkylidyne complexes Ln(RO)3W CR′ (n = 1 or 0) (Schrock et al., Organometallics 1985, 4, 74), alkyne adducts, W2(OR)6(py)n(μ-C2R′2), alkylidyne-capped tritungsten complexes, W3(μ3-CR′)(OR)9, and W2(OR)6(L)(μ-C4R′4) or W2(OR)6(μ-C4R′4) (μ2-C2R′2) compounds. Evidence for equilibria involving alkyne adducts and alkylidyne species is found for certain combinations of R and R′. (1) The alkylidyne complexes (ButO)3 WCMe and (py)2(PriO)3 W CNMe2 react with CO (1 atm 22°C, in hexane) to yield alkyne adducts W2(OBut)6(μ-C2Me2)(CO) and W2[(OPri)6(CO)2(η2-C2(NMe2)2], respectively. (2) The alkylidyne complexes [PriO)2(HNMe2)(R′C)W(μ-OPri)]2 react with alkynes R′CCR′ (> 2 equiv, hexane, 22°C) to give W2(OPri)6(μ-C4R′4)(η2-C2R′2) compound (R′ = Me or Et). (3) The alkyne adducts W2(ONp)6(py)n(μ-C2R′2) (R′ = Et or Ph, n = 1; R′ = Me, n = 2) react with W2(ONp)6(py)2 in a 1:2 mole ratio at 22°C in hexane to yield W3(μ3-CR′)(ONp)(9 compounds. In related reactions involving 1,2-bishydrocarbyl-tetraalkoxides, W2(CH2R″)2(OR)4, and alkynes (R′CCR′) (2 equiv), alkyne adducts of formula W2(CH2R″)2(η2-C2R′2)2(OPri)4 and W2(CH3)2(μ-C2R′2)(OBut)4(py), alkylidyne-bridged complexes HW2(μ-CR″)(μ-C4R′4)(OPri)4 and products of WW and CC metathesis have been isolated for various combinations of R, R′ and R″.