The structure and bond nature for the ground state of the UF5 monomer have been investigated by means of relativistic and nonrelativistic discrete-variational (DV) Xα molecular orbital (MO) methods. It is found that the nonrelativistic calculation provides only less than half of the U-F bond overlap population obtained by the relativistic calculation for the monomer with the C4v geometry which was determined experimentally. Comparison of the U-F bond overlap population and valence level structures between the C4v and D3h geometries indicates that the stability of the D3h monomer is almost equal to that of the C4v one. Furthermore, it is confirmed that an intermediate structure (C2v) between the two geometries shows similar values of effective charge, orbital, and bond overlap populations. This suggests that the energy barrier between the D3h and C4v geometries is very small and the geometry of the UF5 monomer is fluxional between the C4v and D3h, symmetries. This is consisted with the previous results reported by the Hartree-Fock method with relativistic effective core potentials [Wadt, W. R.; Hay, P. J. J. Am. Chem. Soc. 1979, 101, 5198]. The flexibility of the UF5 structure originates from the fact that the U 5f atomic orbitals, which play a major role in the U-F bonding interactions, spread with wide angular distributions of the electrons in hybridization with the U 6d atomic orbital.
|Number of pages||5|
|Publication status||Published - Apr 23 1997|
ASJC Scopus subject areas
- Physical and Theoretical Chemistry
- Inorganic Chemistry