PREPARATION, CHARACTERIZATION AND REACTIVITY OF A SERIES OF CLASSICALAND NONCLASSICAL RHENIUM HYDRIDE COMPLEXES

Hydride complexes [ReH(CO)(4)L] 1, [ReH(CO)(3)L-2] 2, [ReH(CO)(2)L-3] 3 and [ReH(CO)L-4] 4 [L = P(OEt)(3) a, PPh(OEt)(2) b, PPh2(OEt) c or P Ph2(OMe) d] were prepared by treating [ReH(CO)(5)] with the appropriat e phosphite under UV irradiation or reflux. The complexes were charact erised by IR, H-1, C-13 arid P-31 NMR spectroscopy and by crystal stru cture determinations of Id and 2d. Protonation of the monocarbonyls I [ReH(CO)L-4] 4 in CD2Cl2 with HBF4.Et2O resulted in an equilibrium mix ture of the classical dihydride complexes [ReH2(CO)L-4]+BF4- and their non-classical tautomers [Re(eta(2)-H-2)(CO)L-4]+BF4-. The dihydride [ ReH2(CO){PPh(OEt)(2)}(4)]BPh4 was also isolated as a solid by protonat ion of [ReH(CO){PPh(OEt)(2)}(4)] in ethanol. Thermally unstable [Re(et a(2)-H-2)(CO)(4)L](+), [Re(eta(2)-H-2)(CO)(3)L-2](+) and [Re(eta(2)-H- 2)(CO)(2)L-3](+) 7 cations were also prepared by protonation of the co rresponding monohydrides 1, 2 and 3 and fully characterised in solutio n. The unsaturated complexes [Re(CO)(2)L-3]BPh4 and [Re(CO)L-4]BPh4 11 and the triflate [Re(eta(1)-OSO2CF3)(CO)(3)L-2] were obtained from th e eta(2)-H-2, derivatives by evolution of H-2,. The new complexes [Re( C=CPh)(CO)(3)L-2], [Re(C=CPh)(CO)L-4] 13, [Re(4-MeC6H4CN)(CO)(2)L-3]BP h4, [Re(4-MeC6H4NC)(CO)(2)L-3]BPh4 and [Re(4-MeC6H4NC)(CO)L-3]BPh4 wer e prepared by treating the triflate compounds or the unsaturated compo unds [Re(CO)(2)L-3]BPh4 and [Re(CO)L-4]BPh4 with Li+C=CPh- or with the appropriate ligand.