A density functional theory study on the LRh"H4" (L = Cp, Tp) systems has been carried out. When L = Cp, a piano-stool tetrahydride structure has been found to be the most stable, and a η2-H2structure has been found slightly higher in energy. Conversely, when L = Tponly an octahedral dihydrogen-dihydride structure has been determined. Rotational barriers corresponding to dihydrogen-dihydride structures when L = Cp and L = Tpare obtained and their differences are interpreted in terms of the dependence of π-back-donation along the librational motion of the dihydrogen unit. Finally, a value of 9.2 cm-1has been theoretically determined for the rotational tunneling splitting of the librational ground state of TpRh(η2-H2)H2, in excellent accord with experimental measurements obtained by means of INS experiments.
|Publication status||Published - 19 Aug 1997|