88211-52-3Relevant articles and documents
Molecular Hydrogen Complexes of the Transition Metals. 4. Preparation and Characterization of M(CO)3(PR3)2(η2-H2)(M = Mo, W) and Evidence for Equilibrium Dissociation of the H-H bond To Give MH2(CO)3(PR3)2
Kubas, Gregory J.,Unkefer, Clifford J.,Swanson, Basil I.,Fukushima, Eiichi
, p. 7000 - 7009 (2007/10/02)
The syntheses, properties, and spectral characterization of the first examples of molecular hydrogen complexes, M(CO)3(PR3)2(H2) (M = Mo, W; R3 = Cy3, i-Pr3, Cy2-i-Pr), are reported in full.All six of the expected fundamental vibrational modes for η2-H2 binding, including ν(HH) at 2690 cm-1, have been located.The hydrogen atoms of the H2 ligand, but not of the phosphines, undergo exchange with D2 to give HD, even in the solid state.Solid-state 2H NMR of W(CO)3(P-i-Pr3)2(D2) shows rapid rotation of the D2 about the metal-D2 axis.IR and variable-temperature 1H and 31P NMR of solutions of the H2 complexes reveal the presence of equilibrium amounts (10-30percent) of a species that the data indicate is a 7-coordinate dihydride, MH2(CO)3(PR3)2.The latter is presumably formed by dissociation of the H-H bond, thus completing oxidative addition of H2 to the metal.The dihydride is fluctional, but low-temperature NMR spectroscopy shows that both the hydride and phosphorus ligands are inequivalent.At -80 deg C the T1 value for the 1H NMR signal of the H2 ligand is 0.004 s, almost three orders of magnitude less than that of the hydride protons (1.7 s) in WH2(CO)3(P-i-Pr3)2.
