The tunnel splitting of the librational ground state and the torsional frequencies of the dihydrogen ligand in TpMe2:RhH2 (η2-H2 ) (TpMe2 = hydrotris(3,5-dimethylpyrazolyl)borate) were measured using inelastic neutron scattering spectroscopy. The barrier for the rotation of the H2 ligand and its H-H separation, calculated from these data, are 0.56(2) kcal/mol and 0.94 Å, respectively. These values indicate that π-back-donation from the TpMe2RhH2 fragment to H2 is relatively weak and/or the interaction between the coordinated dihydrogen molecule and the two cis-hydride ligands significantly lowers the barner for H2 rotation.
|Number of pages||3|
|State||Published - 1996|