Group-6 metal carbonyl complexes of pyridylbenzoxazole and pyridylbenzothiazole: Synthesis, structure, electrochemistry, photophysical property and DFT calculations

Cr, Mo and W tetracarbonyl complexes of 2-(2-pyridyl)benzoxazole (PBO) and 2-(2-pyridyl)benzothiazole (PBT) are spectroscopically characterised. The confirmatory structure of [Mo(CO)4(PBO)] has been determined by X-ray crystallography. The complexes show negative solvatochromic effect, with increasing solvent polarity the MLCT band is shifted to longer wavelength region. Cyclic voltammetry shows M(I)/M(0) redox response and also exhibit fluorescence spectra at room temperature. The electronic structures of the complexes are calculated by density functional theory (DFT) and time dependent-DFT calculated results are used to explain redox property and electronic transitions.

Graphical abstractGroup-6 tetracarbonyl complexes of pyridylbenzoxazole and pyridylbenzothiazole have been reported. X-ray structure of [Mo(CO)4(PBO)] (PBO = 2-(2-pyridyl)benzoxazole) showed distorted octahedral geometry. The complexes exhibit negative solvatochromic property and fluorescence spectra at room temperature. Cyclic voltammetry shows M(I)/M(0) oxidation couple and ligand reduction. DFT and TDDFT calculation explain absorption and redox properties.Figure optionsDownload full-size imageDownload as PowerPoint slide