NMR and theoretical study on interactions between diperoxovanadate complex and pyrazole-like ligands |
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| Authors: | Xianyong Yu Ronghua Liu Hongliang Peng Haowen Huang Xiaofang Li Baishu Zheng Pinggui Yi Zhong Chen |
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| Institution: | 1. Key Laboratory of Theoretical Chemistry and Molecular Simulation of Ministry of Education, Hunan Province College Key Laboratory of QSAR/QSPR, School of Chemistry and Chemical Engineering, Hunan University of Science and Technology, Taoyuan Road, Xiangtan, Hunan 411201, China;2. State Key Laboratory of Physical Chemistry of Solid Surface, Fujian Key Lab of Plasma and Magnetic Resonance, Department of Physics, Xiamen University, Xiamen 361005, China |
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| Abstract: | To understand the effects of pyrazole substitution on reaction equilibrium, the interactions between a series of pyrazole-like ligands and OV(O2)2(D2O)]?/OV(O2)2(HOD)]? were explored by using multinuclear (1H, 13C, and 51V) magnetic resonance, HSQC, and variable temperature NMR in 0.15 mol/L NaCl ionic medium mimicking physiological conditions. These results show that the relative reactivities among the pyrazole-like ligands are 3-methyl-1H-pyrazole ≈ 4-methyl-1H-pyrazole ≈ 1H-pyrazole > 1-methyl-1H-pyrazole. As a result, the main factor which affects the reaction equilibrium is the steric effect instead of the electronic effect of the methyl group of these ligands. A pair of isomers has been formed resulting from the coordination of 3-methyl-1H-pyrazole and a vanadium complex, which is attributed to different types of coordination between the vanadium atom and the ligands. Thus, the competitive coordination leads to the formation of a series of six-coordinate peroxovanadate species OV(O2)2L]? (L, pyrazole-like ligands). Moreover, the results of density functional calculations provided a reasonable explanation on the relative reactivity of the pyrazole-like ligands as well as the important role of solvation in these reactions. |
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