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Reaction of [WMe(CO) 3 (η-C 5 H 5 )] with LiBHEt 3 . Formation and reactions of the anionic formyl trans-[W(CHO)Me(CO) 2 (η-C 5 H 5 )] – and the anionic hydrido acyl trans-[WH(COMe)(CO) 2 (η-C 5 H 5 )] –

1991; Royal Society of Chemistry; Issue: 6 Linguagem: Inglês

10.1039/dt9910001427

2050-5671

J. Trevor Gauntlett, Brian E. Mann, Mark J. Winter, Simon Woodward,

Asymmetric Hydrogenation and Catalysis

Addition of LiBHEt3 to [WMe(CO)3(η-C5H5)]5 at –70°C results in the formation of the formyl trans-[W(CHO)Me(CO)2(η-C5H5)]–7. In solution, this species exists as a mixture of two BEt3 adducts and a BEt3-free species. All the formyl species undergo chemical exchange at –50°C. Warming of the reaction mixture to ambient temperature results in solutions containing the anionic hydrido acyl complex trans-[WH(COMe)(CO)2(η-C5H5)]–6 isolable as a boron-free salt [Li(12-crown-4)2][WH(COMe)(CO)2(η-C5H5)](12-crown-4 = 1,4,7,10-tetraoxacyclododecane). This moisturesensitive anion gives [W(CO)3(η-C5H5)]– on exposure to water and undergoes hydride for halide (X) exchange on low-temperature treatment with CCl4, CBr4 or CHI3 forming the reactive anions [WX(COMe)(CO)2(η-C5H5)]–8–10. The major product of warming these halogenoacyl anions is 5. Addition of [Me3O][BF4] to boron-free solutions of [WI(COMe)(CO)2(η-C5H5)]–10 results in the new carbene trans-[WI{C(OMe)Me}(CO)2(η-C5H5)]11, while treatment with SiMe3Cl followed by low-temperature filtration through silica gives the hydroxycarbene trans-[Wl{C(OH)Me}(CO)2(η-C5H5)]12.