Azobased iminopyridine ligands and their rhenium metal complexes: Syntheses, spectroscopic, trans-cis photoisomerization and theoretical studies

The reaction of rhenium(I) pentacarbonyl chloride Re(CO)(5)Cl with N,N-dimethyl-4-((E)-(pyridin-2-ylmethylene) amino)phenyl) diazenyl) aniline L and (E)-4-((E)-(4-nitrophenyl)diazenyl)-N-(pyridin-2-ylmethylene) aniline L2 affords two rhenium metal complexes [ReL1(CO)(3)Cl] (ReL1) and [ReL2(CO)(3)Cl] (ReL2), respectively. These Re(I) complexes were characterized in detail, including their single crystal structures, absorption spectra and electronic structures using DFT calculations. Trans to cis photoisomerization of the free ligands and complexes was investigated experimentally and rationalized theoretically. Interestingly, light-induced photoisomerization of the azo fragment is observed for free ligand Ll while inhibition of this process is produced upon coordination to Re metal cation.