DFT study on CH⋯O, CH···SCN and S···π interaction energies in three dinuclear mixed valence cobalt(III/II) complexes with secondary diamine ligands having inner N2O2 and outer O4 compartments

Abstract

Three dinuclear cobalt(III/II) mixed valence reduced Schiff base complexes, [(N3)CoIIIL(μ-O2CR1)CoII(N3)] (1), [(SCN)CoIIIL(μ-O2CR2)CoII(NCS)] (2) and [(SCN)CoIIIL(μ-O2CR3)CoII(NCS)] (3) {H2L= (2,2-dimethyl-1,3-propanediyl)bis(iminomethylene)bis(6-ethoxyphenol); R1CO2H = 4-methyl-3-nitrobenzoic acid; R2CO2H = benzoic acid; R3CO2H = 3-methyl-4-nitrobenzoic acid} have been synthesized and characterized by elemental analysis and spectral study. X-ray diffraction analysis was used to determine the structures of all three complexes. Spin density calculations have been used to determine the location of the paramagnetic cobalt(II) center in each of the dinuclear complexes. Moreover, several supramolecular assemblies (formed by CH⋯O, CH···SCN and S··· π and other interactions) observed in the solid state of the three complexes involving the pseudohalide as electron donors have been analysed using DFT calculations, molecular electrostatic potential (MEP) surfaces and characterized using the noncovalent interaction plot (NCI Plot) index.