Cyclopentoxyditungsten compounds and crystal and molecular structures and dynamic solution behavior of W sub 2 (. mu. -H)(O-c-C sub 5 H sub 9 ) sub 7 (HNMe sub 2 )

The reaction between W{sub 2}(NMe{sub 2}){sub 6} and cyclopentanol ({ge}6 equiv) in hexane solvents initially forms the dimethylamine adduct W{sub 2}(O-c-C{sub 5}H{sub 9}){sub 6}(HNMe{sub 2}){sub 2} but with time in the presence of cyclopentanol and dimethylamine the hydrido-bridged compound W{sub 2}({mu}-H)(O-c-C{sub 5}H{sub 9}){sub 7}(HNMe{sub 2}) is formed and may be isolated as green crystals. Crystal data at {minus}155C: a = 13.057 (3) {angstrom}, b = 15.592 (4) {angstrom}, c = 10.376 (2) {angstrom}, {alpha} = 97.72 (1){degree},{beta} = 109.55 (1){degree}, {gamma} = 94.22 (1){degree}, {zeta} = 2,d{sub calcd} = 1.738 g cm{sup {minus}3}, and space group P1. The bridging hydride was not located crystallographically but can be inferred to occupy a position trans to the HNME{sub 2} ligand so as to complete a confacial bioctahedron. In solution, the molecule is fluxional and the dimethylamine is labile and has been replace by PMe{sub 3}. Variable-temperature H and P NMR studies reveal that the (RO){sub 3}W({mu}-H)({mu}-OR){sub 2}W(OR){sub 2}(L) molecules are in a temperature dependent equilibrium with the unligated molecule W{sub 2}({mu}-h)(or){sub 7} and the free ligand. At high temperature, rapid OR group scrambling generates two equivalent (time-averaged) W atoms, but at low temperature the NMR spectra are consistent with expectations based onmore » the solid-state structure of W{sub 2}({mu}-H)(O-c-C{sub 5}H{sub 9}){sub 7}(HNMe{sub 2}).« less