Synthesis, structural characterization and DFT study of a cobalt(III)/cobalt(II) complex derived from N,O donor reduced Schiff base ligand

The present work descries the strategic design and synthesis of a dinuclear mixed-valence Co(III)/Co(II) complex, [(N₃)Co^IIIL^r(μ-O₂CR¹)Co^II(N₃)]·CH₃OH, which has been synthesized using an N₂O₄ donor compartmental ligand, H₂L^r {(2,2-dimethyl-1,3-propanediyl)bis(iminomethylene)bis(6-ethoxyphenol)}, CoCl₂·6H₂O, benzoic acid (R¹CO₂H) and NaN₃ in 1: 2: 1: 2 ratio. Single crystal X-ray diffraction structure confirms the presence of a Co₂O₂ core in the complex. Co(III) center is present in the inner N₂O₂ donor pocket and cobalt(II) center is trapped in the outer O₂O′₂ donor pocket, as confirmed by bond length consideration and BVS calculation. Experimental effective magnetic moment supports the presence of three unpaired electron in the complex. DFT calculation is performed to confirm th oxidation state of The high spin configuration is 28.2 kcal/mol more stable than the low spin configuration at the CAM-B3LYP/Lanl2DZ/6-31G(d) level of theory, thus supporting the quadruplet nature of the complex.