Comparative relativistic effective core potential ab initio calculations for both Th(IV) and U(IV) Cp3AnL (Cp = η5-C5H5; L = CH3, BH4) complexes are reported. The Cp-An bonding appears to be dominated by metal 6d orbitals interacting with ligand π2 orbitals. Metal 5f orbitals provide a smaller contribution but are crucial for stabilization of the Cp3An cluster. The stability of the An-CH3 bonding depends upon interactions involving metal 6dz2-based orbitals directed along the An-CH3 vector. The L = BH4 ligand interactions are mediated by dxz and dyz atomic orbitals, which are even better suited for favorable overlap and, hence, for greater metal-ligand π covalency. Ground 3A2 states have been found to be the most stable for the U(IV) complexes. The experimental He I/He II photoelectron data are consistent with the quantum chemical calculations and indicate a close similarity between ground-state properties of the present Th(IV) and U(IV) complexes.
ASJC Scopus subject areas
- Physical and Theoretical Chemistry