Oxidation and reduction response of α-diimine complexes with tricarbonylrhenium halides and pseudohalides

Compounds [Re(CO)3X(R-DAB)], X = Cl, Br, CN, NCS and R-DAB = RNdouble bond; length as m-dashCH–CHdouble bond; length as m-dashNR (R = tert-butyl) were obtained, structurally characterized, and studied with regard to their oxidation and reduction behavior using cyclic voltammetry, EPR, IR and UV–vis–NIR spectroelectrochemistry. Whereas the halide compounds exhibit more reversible oxidation processes, the pseudohalide complexes display reversible one-electron reduction but irreversible oxidation. DFT and TD-DFT calculations were employed to confirm the experimentally derived electronic structures and spectral properties.