fac-Tricarbonyl rhenium(I) complexes of 2-(alkylthio)-N-((pyridine-2-yl)methylene)benzenamine: Synthesis, spectroscopic characterization, X-ray structure and DFT calculation

The paper presents a combined experimental and computational study of tricarbonyl complexes fac-[Re(CO)3(L1/L2)Cl] (1a/1b) (L1 = 2-(methylthio)-N-((pyridine-2-yl)methylene)benzenamine and L2 = 2-(ethylthio)-N-((pyridine-2-yl)methylene)benzenamine). The Schiff base ligands L1 and L2 have been synthesized and characterized by elemental and spectroscopic analysis. Along with spectral characterizations, the structural confirmation by single crystal X-ray study has been done for complex 1a. The rhenium atom adopts a distorted octahedral geometry and is coordinated by three carbonyl ligands in a fac arrangement. The electronic structure, redox properties, absorption and emission properties of ligands and complexes have been explained based on DFT and TDDFT calculations. The complexes show MLCT bands at 443–448 nm and emitted at 405–410 nm upon excitation at 320–326 nm, characterized as ILCT transitions.