Nature of the Transition Metal−Cycloheptatrienyl Bond. Computational Studies of the Electronic Structure of [M(η7-C7H7)(η5-C5H5)] (M = groups 4−6)

Abstract

The geometric and electronic structures of the title compounds are investigated using relativistic, gradient-corrected density functional theory. The metal−ligand bond lengths in the transactinide compounds are found to be generally larger than for the 3d, 4d, and 5d systems, suggesting that the actinide contraction is not significantly bigger than the lanthanide analogue. Excellent agreement is obtained between computed and experimental valence ionization energies. The localization properties of the key 1e2 electrons are analyzed and suggest that the cycloheptatrienyl ring functions more as a −3 ligand than as a +1 ligand in these mixed ring complexes. Comparisons are made with previous photoelectron spectroscopic determinations of the character of the 1e2 electrons. The metal−cycloheptatrienyl bonding energies are calculated and are found to be weakest for the transactinide molecules.