Synthesis and characterization of rhenium polyhydrides stabilized by the tripodal ligand MeC(CH2PPh2)3

Article abstract of DOI:10.1016/0022-328X(93)83013-L

The reaction of CH3C(CH2PPh2)3 (triphos) with in THF at reflux temperature yields <(η²-triphos)Re(O)Cl3> (3).Compound 3 is transformed into <(η²-triphos)ReH7> (4) by treatment with LiAlH4 in refluxing THF.The reaction of with triphos in refluxing toluene gives fac-<(η³-triphos)ReCl3> (5) in excellent yield.Complex 5 is converted to the classical pentahydride <(η³-triphos)ReH5> (6) by treatment with NaBH4 at room temperature.The reductve elimination of H2 from 6 is promoted by monodentate ligands such as PPh3 and CO, giving substitution products of the formula <(η³-triphos)ReH3(L)> (L = PPh3 (7) or CO (8)).All the rhenium polyhydrides obtained have been characterized by spectroscopic techniques including IR and multinuclear variable-temperature NMR analysis.A detailed study of the spin-lattice relaxation time (T₁) at variable temperature has shown that T₁ cannot be used unambiguously to discriminate between classical and non-classical structures of rhenium polyhydrides.