Theoretical insights into M-SO bonds in transition metal-sulfur monoxide complexes [{N(SPMe2)2}2M(SO)] (M = Fe, Ru, Os): Assessment of density functionals and dispersion interactions

Geometry, electronic structure and bonding analysis of the sulfur monoxide complexes [{N(SPMe2)(2)}(2)M (SO)] (M = Fe, Ru, Os) have been investigated with the DFT, DFT-D3 and DFT-D3(BJ) methods using density functionals BP86, PW91, BLYP, PBE, revPBE, and TPSS. The BP86 and PBE optimized geometries of complex [{N(SPMe2)(2)}(2)Ru(SO)] are in good agreement with the reported experimental values. The Mayer and Gopinathan-Jug bond orders confirm the presence of M-SO and S-O multiple bond characters. Hirshfeld charge analysis shows transfer of electron density from metal fragments to antibonding pi* orbital of SO ligand. Significant noncovalent interactions between metal fragment and SO ligand are observed in the studied sulfur monoxide complexes. Noncovalent M---O and S---SO interactions have been justified by molecular orbital analysis. The M-SO bond dissociation energies vary in the order Fe < Ru < Os and depends on the choice of density functionals. The BP86/D3(BJ) dispersion corrections add 38% to the bond dissociation energy of Fe-SO bond, while only 22% and 17% to Ru-SO and Os-SO bonds, respectively. The pi-bonding contributions to the total M-SO bonds are relatively smaller (22.6-27.0%) than the sigma-bonding contribution. (C) 2015 Elsevier Ltd. All rights reserved.