| Abstract
| - A density functional theory study on the LRh“H4”(L = Cp, Tp) systems has been carriedout. When L = Cp, a piano-stool tetrahydride structure has beenfound to be the most stable,and a η2-H2 structure has been found slightlyhigher in energy. Conversely, when L = Tponly an octahedral dihydrogen−dihydride structure has beendetermined. Rotational barrierscorresponding to dihydrogen−dihydride structures when L = Cp and L= Tp are obtainedand their differences are interpreted in terms of the dependence ofπ-back-donation alongthe librational motion of the dihydrogen unit. Finally, a value of9.2 cm-1 has beentheoretically determined for the rotational tunneling splitting of thelibrational ground stateof TpRh(η2-H2)H2, inexcellent accord with experimental measurements obtained bymeansof INS experiments.
- The DFT methodology has been used to studythe structure and dynamics of LRh“H4” (L = Cp, Tp)systems. The most stable structure is found to be a tetrahydridestructure when L = Cp and a dihydride−dihydrogen structure when L= Tp. Energy barriers for the rotation of theη2-H2 unit in the dihydrogen−dihydrideisomers and for hydride exchange processes are determined for systemswith L = Cp, Tp. Finally, rotational tunneling splitting istheoretically determined forTpRhH2(η2-H2).
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