Accurate Structure and Bonding Description of the Transition Metal-Disulfur Monoxide Complexes [(PMe3)2M(S2O)] (M= Ni, Pd, Pt): Grimme Dispersion Corrected DFT Study

Abstract

Geometry and bonding energy analysis of M–S2O bonds in the metal-disulfur monoxide complexes [(PMe3)2M(S2O)] of nickel, palladium, and platinum were investigated at DFT, DFT-D3, and DFT-D3(BJ) methods using three different functionals (BP86, PBE, and TPSS). The TPSS/DFT-D3(BJ) yields better geometry, while the BP86 geometry is least accurate for studied complexes. The geometry of platinum complex optimized at TPSS/DFT-D3(BJ) level is in excellent agreement with the available experimental values. The M–S bonds are shorter than the M–S(O) bonds. The Mayer bond orders suggest the presence of M–S and M–S(O) single bonds. Both the M–S and M–S(O) bond lengths vary with the density functionals as TPSS-D3(BJ) < TPSS < PBE < BP86. The Hirshfeld charge distribution indicates that the overall charge flows from metal fragment to [S2O]. The Ni–S2O bond has greater degree of covalent character than the ionic. The contribution of dispersion interactions is large in computing accurate bond dissociation energies between the interacting fragments. The BDEs are largest for the functional TPSS and smallest for the functional BP86. The DFT-D3 dispersion corrections to the BDEs between the metal fragments [(PMe3)2M] and ligand fragment [(S2O)] for the TPSS functional are in the range 7.1–7.3 kcal·mol–1, which are smaller than the corresponding DFT-D3(BJ) dispersion corrections (9.4–10.6 kcal·mol–1).