Structural elucidation, DFT calculations and catalytic activity of dioxomolybdenum(VI) complexes with N-N donor ligand: Role of halogen atom coordinated to the molybdenum centre

Two new isostructural mononuclear dioxomolybdenum(VI) complexes of the formula MoO2X2L [where, X = Cl (1), Br (2)] have been synthesized with a N-N donor 2-(3-methyl-5-phenyl pyrazol-1-yl) benzthiazole ligand (L). The reaction is carried out in open air and the (MoO3+)-O-V centre in the precursor molecule, MoOX3L undergoes spontaneous aerial oxidation, leading to the formation of molybdenum(VI) complexes 1 and 2. The complexes are characterized by a wide range of spectroscopic techniques (IR, UVVis and H-1 NMR) and elemental analyses. Crystal structures of the ligand and complexes 1 and 2 have been determined by single crystal X-ray diffraction which reveal a distorted octahedral geometry around the molybdenum(VI) centre in both the complexes. The ligand and the complexes build up fascinating supramolecular assembly via several non-covalent interactions including hydrogen bonding, C-H center dot center dot center dot pi and pi center dot center dot center dot pi interactions. Further, a detailed study of Hirshfeld surface analysis and fingerprint plots of complexes 1 and 2 are presented for understanding the intermolecular interactions involved in building selfassembled frameworks. Supportive DFT and TD-DFT calculations have also been carried out. Electrochemical properties of the complexes have been examined by cyclic voltammetry. Catalytic performance of the synthesized complexes has been evaluated for the oxidation of different olefins in the presence of hydrogen peroxide. (C) 2021 Elsevier Ltd. All rights reserved.

Automated summary

Two new isostructural mononuclear dioxomolybdenum(VI) complexes MoO2X2L (X = Cl, Br) with a N-N donor ligand have been synthesized. The complexes were characterized by various spectroscopic techniques and elemental analyses, with crystal structures determined by single crystal X-ray diffraction. The complexes exhibit a distorted octahedral geometry and form fascinating supramolecular assemblies via non-covalent interactions. Extensive studies on intermolecular interactions, DFT calculations, electrochemical properties, and catalytic performance have been conducted.