Synthesis and Crystal Structure of Cobalt(III) Chelate with Tridentate Azomethine Ligand Containing a Benzimidazole Moiety

Azomethine HL was synthesized by the reaction of o- aminophenol with 2-acetylbenzimidazole and used to prepare the cobalt(III) complex [CoL 2 ] 2 (ClO 4 ) 2 ⋅3H 2 O ( I ). The structure of complex I was established by NMR spectroscopy in solution and by single crystal X-ray diffraction (CIF file CCDC no. 2051279). The cobalt ion in the +3 oxidation state has an octahedral environment. The crystals are monoclinic, space group C 2/ c , a = 12.405(7), b = 13.946(11), c = 18.907(13) Å, α = 109.87(3)°, β = 94.534(12)°, γ = 104.564(19)°, V = 2928(3) Å 3 , ρ(calcd.) = 1.521 g/cm 3 , Z = 2. The complex is diamagnetic. Study of the electrochemical behavior of I in acetonitrile showed that it can be reduced to neutral and radical anion forms.