Charge density distribution and bond characterization of metal dialkyldithiocarbamate complexes (M=Co, Ni)

Abstract

Electron density distribution of metal dithiocarbamate complexes, Co(S 2CNMe 2) 3 and Ni(S 2CNEt 2) 2, are studied both by single X-ray diffraction method and by theoretical quantum molecular orbital calculation. Bond characterization is made in terms of deformation density, topological analysis on total electron density and Fermi hole distribution. The cobalt(III) ion is coordinated with three ‘chemically equivalent’ planar bidentate ligands. The structure of the complex is like a ‘three-bladed propeller’. The Ni(II) ion is coordinated with two ligands in a square planar fashion. Deformation density distribution and topological analysis based on multipole model and molecular orbital calculations (DFT) are performed. The asphericity in electron density around the metal ion is clearly demonstrated; where local electron density accumulation is found at d π directions but local electron density depletion is found at d σ direction. The agreement between experiment and theory is good. The comparison between ligand dimer (S 2CNEt 2) 2, and metal complexes are made. With the topological analysis, the shape of valence shell charge concentration (VSCC) of each atom is illustrated. The bond characterization is made through topological properties associated with bond critical point (BCP). The linear relationship between the electron density at the bond critical point, ρ( r c), and the bond length leads to the conclusion that ρ( r c) is a good indicator of bond strength. The bond type is determined by the Laplacian at BCP, the total energy density at BCP and the Fermi-hole function.