Cobalt-thioalkylazoimidazole complexes: Structures, spectra and redox properties

1-Alkyl-2-{(o-thioalkyl)phenylazo}imidazole (SRaaiNR', 1) reacts with Co(ClO4)(2)center dot 6H(2)O to form [Co(SRaaiNR')(2)](ClO4)(2) (2). The single crystal X-ray structure of one of the complexes of 2 shows a tridentate chelation N(imidazole), N(azo), S(thioether) system. In the structure one of ClO4- anions shows disorder and forms an (imidazole)C-H center dot center dot center dot O(ClO3) interaction leading to a 1-D chain. Co(OAc)(2)center dot 4H(2)O and SRaaiNR' react in the presence of NH4SCN (1:1:2 mole ratio) in methanol and the complex [Co(SRaaiNR')(2)(SCN)(2)](3) has been separated. The single crystal X-ray structure determination has established the structure of the complexes in which the ligand SRaaiNR' acts in a bidentate N(imidazole), N(azo) chelation mode. A cyclic voltammogram shows a Co(III)/Co(II) oxidative response at 0.6-0.8 V and azo reductions. DFT computation using optimized geometry support the electronic spectral and redox properties of the complexes. (c) 2009 Elsevier Ltd. All rights reserved.