183472-57-3Relevant academic research and scientific papers
Structure and H2-Loss Energies of OsHX(H2)(CO)L2 Complexes (L = P(t-Bu)2Me, P(i-Pr)3; X = Cl, I, H): Attempted Correlation of 1J(H-D), T1min, and ΔG
Gusev, Dmitry G.,Kuhlman, Roger L.,Renkema, Kenton B.,Eisenstein, Odile,Caulton, Kenneth G.
, p. 6775 - 6783 (2008/10/09)
1J(H-D), T1min mm and k1 for H2 dissociation from OsCl2(H2)(CO)L2 have been measured for X = Cl, I, H (L = P(t-Bu)2Me or P(i-Pr)3), as well as for OsCl2(H2)(CO)(P(i-Pr)3)2. For comparison, new data (including previously unobserved coupling constants) have been reported for W(HD)(CO)3(P(i-Pr)3)2. A comprehensive consideration of T1min data for over 20 dihydrogen complexes containing only 1-2 phosphines cis to H2, together with a consideration of the shortest conceivable H-H distance for H2 bound to a d4 or d6 metal, is used to argue that the fast spinning model is not appropriate for determining r(H-H) in such complexes. Regarding OsHX(H2)-(CO)L2, the stronger electron-donor (lighter) halide, when cis to H2, facilitates loss of H2. The complete absence of π-donor ability when X = H renders H2 loss most difficult. However, a π-donor trans to H2 also makes H2 loss unobservable. Within the series of isoelectronic, structurally analogous Os complexes, a longer H-H bond shows a larger ΔG? for H2 loss. However, this correlation does not continue to W(H2)(CO)3(P(i-Pr)3)2, which has r(H-H) comparable to that of OsH(halide)(H2)(CO)(P(i-Pr)3)2, but a significantly higher ΔG?. This may originate from lack of a π-donor ligand to compensate as H2 leaves W.
