Abstract
Two binucelar oxidovanadium complexes, [(VO2)2(µ-Hpydn)2] (1) and [(VO)2(µ-pydn)2(bpy)2]·5H2O (2), where pydn = pyridoxine and bpy = 2,2’-bipyridine, were synthesized and characterized by elemental analysis and infrared (IR), electron paramagnetic resonance (EPR), and electronic (UV-vis) spectroscopies. The structure of 2 was determined by single-crystal X-ray diffraction analysis. It is comprised of two distorted octahedral oxidovanadium(IV) centers with a terminal bpy ligand and bridged by the methoxido group of the pydn ligands, forming the {VIVO(µ-OR)2}2+ core with anti-orthogonal configuration. Density functional theory (DFT) calculations at the B3LYP/LANL2DZ level were used to obtain the optimized geometries and to study the electronic structure of 1 and 2. For 2, EPR analysis in the solid state, magnetic susceptibility measurements and the theoretical magnetic exchange coupling constant (J) of 20.1 cm−1 indicate a weak ferromagnetic coupling. 51V NMR and EPR spectroscopies suggest partial breakage of both binuclear structures in solution. Both complexes act as pre-catalysts for the bromination of phenol red to phenol blue in the presence of KBr, H2O2 and perchloric acid.
Graphical Abstract
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Supplementary information
The supplementary material associated with this article can be found in the online version. Crystallographic data for both products have been deposited as CIF files at the Cambridge Crystallographic Data Center with deposition numbers 2129316 for 1 and 2129317 for 2. The files can be obtained free at http://www.ccdc.cam.ac.uk/structures.
Acknowledgements
Authors thank LAMAQ/UTFPR for the ICP-OES analyses. E. L. S. is grateful to the Laboratório Central de Processamento de Alto Desempenho (LCPAD/UFPR) for providing access to computational infrastructure. Authors gratefully thank Dr Jaisa Fernandes Soares and Dr Ronny Rocha Ribeiro for discussions and helpful suggestions. J.M.M., R.C.R.B., G.B.B., F.S.S., D.S., E.L.S and G.G.N. thank CNPq, CAPES-PrInt (Finance Code 001) and pesquisa/PRPPG/UFPR for research grants and scholarships.
Disclosure statement
No potential conflict of interest was reported by the author(s).