Synthesis of [W(eta(5)-C5H5)(2)H(L)](+) and [W(eta(5)-C5H5)(2)L(2)](2+) cations (L=NCMe, NCPh, C4H8O or CNBu(t)). Crystal and molecular structures of [W(eta(5)-C5H5)(2)H(C4H8O)][CF3SO3] and [W(eta(5)-C5H5)(2)-(NCMe)(2)][CF3SO3](2)

The cationic hydride complexes [W(eta-C5H5)(2)H(L)][CF3SO3] [L = NMCe, NCPh, tetrahydrofuran (thf) or CNBut] have been synthesized by reaction of [W(eta-C5H5)(2)H-2] and methyl trifluoromethanesulfonate in the presence of the sigma-donor ligand L. Kinetic measurements on ligand-substitution reactions in CD3CN solution indicate that L is labile in solution; [W(eta-C5H5)(2)H(L)](+) cations have half-lives of 315(10), 122(6) and 6.68(5) h (L = NCMe, NCPh of thf respectively) at 44-degrees-C. The activation energy E(a) for tetrahydrofuran substitution in [W(eta-C5H5)(2)H(thf)](+) is 132 +/- 1 kJ mol(-1). An X-ray crystallographic determination of the structure of [W(eta-C5H5)(2)H(thf)][CF3SO3] demonstrates that the tetrahydrofuran ligand is oriented 'in-plane' with the centroid-W-centroid plane, indicating that the thf acts as a simple sigma-donor ligand. Reaction of [W(eta-C5H5)(2)H-2] with an excess of CF3SO3Me yields the dicationic tungstenocene complex [W(eta-C5H5)(2)(NCMe)(2)][CF3SO3](2) as demonstrated by IR and NMR spectroscopy and X-ray crystallography