Rhenium(I) carbonyl complexes with redox non-innocent 1-alkyl-2-{(o-thioalkyl)phenylazo}imidazole ligands: An experimental and theoretical studies

Abstract The new rhenium(I) carbonyl complexes containing {Re(CO) 3 } + fragment with redox non-innocent ligands L 1 /L 2 (L 1 , 1-methyl-2-{( o -thiomethyl)phenylazo}imidazole and L 2 , 1-ethyl-2-{( o -thioethyl)phenylazo}imidazole) having general formula fac -[ReX(CO) 3 (L 1 /L 2 )] ( 1 / 2 ) (X = Cl ( 1 ) and Br ( 2 )) have been synthesized and characterized by both experimental and theoretical studies. The structural confirmation has been carried out for 1a . The complexes show one irreversible Re I /Re II oxidation and one reversible along with an irreversible ligand reduction in the cyclic voltammetric studies. The electronic structure and the nature of Re–CO bonding has been explained by means of DFT and NBO calculations. The spin allowed singlet–singlet electronic transitions of 1a and 2a have been calculated with TDDFT method, and the experimental spectra of the complexes have been discussed on this basis.