Photoelectron spectroscopy of f element organometallic complexes. 11. An investigation of the electronic structure of some tris(.eta.5-cyclopentadienyl)thorium(IV) and -uranium(IV) complexes by relativistic effect core potential ab initio calculations and gas-phase UV photoelectron spectroscopy

Abstract

Comparative relativistic effective core potential ab initio calculations for both Th(IV) and U(IV) Cp 3 AnL (Cp =η 5 -C 5 H 5 ;L=CH 3 , BH 4 ) complexes are reported. The CP-An bonding appears to be dominated by metal 6d orbitals interacting with ligand π 2 orbitals. Metal 5f orbitals provide a smaller contribution but are crucial for stabilization of the Cp 3 An cluster. The stability of the An-CH 3 bonding depends upon interactions involving metal 6d z2 -based orbitals directed along the An-CH 3 vector. The L=BH 4 ligand interactions are mediated by d xz and d yz atomic orbitals, which are even better suited for favorable overlap and, hence, for greater metal-ligand π covalency