The 2-hydroxybenzaldehyde [(1E)-1-pyridin-2-ylethylidene] hydrazone (HL2) ligand was prepared and its rhenium(I) complexes [ReX(CO) 3(HL2)] were obtained by reaction with fac-[ReX(CO) 3(CH3CN)2] (X = Cl, Br) in chloroform. The compounds were characterized by elemental analysis, mass spectrometry, and IR, UV/Vis, and 1H NMR spectroscopy. Furthermore, the structures were also established by X-ray diffraction. The aromatic rings are almost coplanar in the ligand structure, and the configuration around the hydrazone group is strongly dominated by the presence of an intramolecular hydrogen bond between the OH group and the hydrazinic nitrogen atom N1. The rhenium center is coordinated through the pyridine and hydrazinic nitrogen atoms to give a five-membered chelate ring. In addition, the free ligand shows interesting luminescence properties. The effect of the metal coordination on the photophysical behavior of the resulting complex was also studied.
- Carbonyl ligands