A rare cobalt(III) paramagnetic derivative incorporating 1-alkyl-2-[(o-thioalkyl)phenylazo]imidazole (SMeaaiNEt): EPR, redox and magnetic interpretation

The condensation of 1-alkyl-2-{(o-thioalkyl)phenylazo}imidazole (SMeaaiNEt), Co(ClO₄)₂, 6H₂O and NaN₃ in methanol affords a rare Co(III) paramagnetic complex [Co(SMeaaiNEt)(N₃)₃] (1). Single crystal X-ray diffraction study of complex 1 reveals that the Co(III) possesses a distorted octahedral environment. The EPR study interprets an unusual high-spin Co(III) species with configuration t_2g⁴e_g² and S = 2. The temperature dependent magnetic interpretation agrees with the existence of intermolecular antiferromagnetic coupling on the paramagnetic Co(III) center. A cyclic voltammetry study displays for complex 1 two quasi-reversible and one irreversible responses at the negative direction which may be assigned to different reduction systems. DFT computation using optimized geometry is governed to explain the electronic nature of cobalt derivative which is in accordance with the experimental evidence.