Cobalt-thioalkylazoimidazole complexes: Structures, spectra and redox properties

Abstract

1-Alkyl-2-{( o-thioalkyl)phenylazo}imidazole (SRaaiNR /, 1) reacts with Co(ClO 4) 2·6H 2O to form [Co(SRaaiNR /) 2](ClO 4) 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 ClO 4 − anions shows disorder and forms an (imidazole)C–H···O(ClO 3) interaction leading to a 1-D chain. Co(OAc) 2.4H 2O and SRaaiNR / react in the presence of NH 4SCN (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.