Dispersion interactions with density functional theory: Bonding description of V-NS bond in vanadium-thionitrosyl complex [(nacnac)(OAr)V(NS)]

摘要

Dispersion corrected quantum chemical calculations of the complex [(nacnac)(OAr)V(NS)] were investigated at DFT, DFT-D3 and DFT-D3(BJ) level using BP86, PBE, revPBE, PW91 and TPSS functionals. The V-NS bond has essentially multiple bond character. The V-NS bond is relatively stronger than the calculated V-NO bond in the complex [(nacnac)(OAr)V(NO)]. The thionitrosyl ligand is stable in doublet state while [V(nacnac)(OAr)] fragment is stable in quartet state. The V-NS bond dissociation energies considering either doublet or quartet states of the interacting fragments vary in the order 77.2(revPBE)<82.1(BP86)<87.1 (PW91). The dispersion interaction energy has significant contribution to the V-NS bond dissociation energy. The dispersion corrections with DFT-D3 methods are smaller than the corresponding DFT-D3(BJ). The V-NS bond has a larger covalent character than the ionic character.