INSERTION REACTIONS OF BIS(ETA-5-CYCLOPENTADIENYL)-DIHYDRIDOTUNGSTEN WITH ACTIVATED OLEFINS AND WITH ACETYLENES - TUNGSTENOCENE ALKYL HYDRIDES, OLEFIN AND ACETYLENE COMPLEXES

Tungstenocene dihydride 1 undergoes insertion of activated olefins at 120-degrees-C to give functional alkyl hydrides Cp2WH(eta-1-CHXCH2R) (X = CO2Me, R = H (2), CO2Me (3), Ph (4); X = CN, R = H (5)). In the case of acrylonitrile the olefin complex Cp2W(eta-2-CH2CHCN) (8) may also be formed. Complexes 2 and 3 were oxidized with chloroform to give the corresponding alkyl chloro complexes 17 and 18. The reaction of 1 with activated acetylenes can produce olefin complexes Cp2W(eta-2-CH2 = CHY) (Y = CO2Me (6), COMe (7)), but in the case of CF3C = CH alkenyl complexes Cp2WX[eta-1-C(CF3) = CH2] (X = H (15), F (16)) are formed. Complex 1 also reacts with diphenylacetylene to give an (E)-stilbene complex Cp2WH[eta-2-(E)-CHPhCHPh] (9) and a tolan complex Cp2W(eta-2-C2Ph2) (12); the (Z)-stilbene complex 10 is observed as an intermediate. Phenylacetylene likewise gives a styrene complex 11. Both 12 and 9 can be reversibly protonated at the tungsten centre; the corresponding cations were characterized as PF6- derivatives 13 and 14. In the case of 4 the regiochemistry of the olefin insertion was established by an X-ray structural determination.