Energy decomposition analysis of the metal-oxime bond in [M{RC(NOH)C(NO)R}2] (M = Ni(II), Pd(II), Pt(II), R = CH3, H, F, Cl, Br, Ph, CF3)

Quantum chemical calculations using gradient-corrected DFT at the BP86/TZ2P+ level were carried out for the metal-dioxime complexes [M{RC(NOH)C(NO)R}(2)] with M = Ni, Pd, Pt, R = CH3, H, F, Cl, Br, Ph, CF3. The nature of the metal-ligand bond was investigated with an energy decomposition analysis (EDA). The complexes with electron donating substituents R = H, CH3 have the strongest metal-ligand interaction energies Delta E-int, as well as the largest bond dissociation energies. The analysis of the bonding situation revealed that the metal <- ligand sigma donation is much stronger than the metal -> ligand pi backdonation. The breakdown of the orbital interactions into the contributions of orbitals with different symmetry indicates that the donation from the in-plane lone-pair donor-orbitals of nitrogen into the d(xy) AO of the metal provides about one half of the stabilization which comes from Delta E-orb. Inspection of the EDA data indicates that the electrostatic term Delta E-elstat is more important for the trend of the metal-oxime interactions in [M{RC(NOH)C(NO)R}(2)] than the orbital term Delta E-orb. (C) 2011 Elsevier B. V. All rights reserved.