The effect of diamine chain length on the formation of CoIII Schiff base complexes: The unexpected formation of a neutral complex containing a tetradentate ligand

The mononuclear neutral CoIII complex [Co(mdbp)L] (3), [mdbpH = 4-methyl-2,6-dibenzoylphenol, LH2[(6-PhCO)(4-Me)(OH)C6H2-2-{CPhN(CH2)4NCPh}-2-C6H2(OH)(4-Me)(6-COPh)], has been synthesized from CoII chloride, butane-1,4-diamine and mdbpH, and its structure established by X-ray crystallography. The Schiff base LH2 and compound 3 have been characterized by elemental analysis, conductivity measurement, mass spectrometry, IR, electronic, 1H and 13C NMR spectroscopy, thermal analysis (TGA) and cyclic voltammetry. The ligand L is tetradentate, and coordinates via phenolato oxygen and imine nitrogen. The octahedral coordination sphere is completed by the phenolato and one benzoyl oxygen of a 4-methyl-2,6-dibenzoylato ligand.