Nature of the metal-ligand bond in trivalent neodymium complexes with neutral pi-donor ligands. A theoretical study

The nature of bonding and energetics in trivalent rare earth pi -donor liga nd complexes [NdCl3-piL] and [NdCp2-piL](+) have been investigated theoreti cally by employing Hartree-Fock (HF) and density functional theory (DFT) ba sed methods. Acetylene, ethylene, butadiene, and benzene served as model pi -ligands. Geometries and binding energies are reported. The analysis prese nted in this study clearly indicates the essentially electrostatic characte r of that binding interaction in terms of a cation-pi -ligand interaction. The lanthanide to pi -ligand bonding was predicted to be weak, accompanied with a slight distortion of the ligand's geometry upon coordination. The ro le of electron correlation does not appear to be crucial in correctly predi cting the metal-ligand interaction energy and the ligand distortion. (C) 20 01 Elsevier Science B.V. All rights reserved.