Crystal structure and NMR study of a bisperoxovanadium complex [NH4][VO(O2)2(ima)] |
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| Authors: | Shaowei Zhang Wen Xia Yueyue Yang |
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| Institution: | Key Laboratory of Theoretical Organic Chemistry and Functional Molecule, Ministry of Education, National Demonstration Center for Experimental Chemical Engineering and Materials, School of Chemistry and Chemical Engineering, Hunan University of Science and Technology, Xiangtan, China |
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| Abstract: | A novel bisperoxovanadium complex, NH4]VO(O2)2(ima)] (1) (ima = imidazole-4-carboxamide), was synthesized by the reaction of NH4VO3 and ima in the presence of H2O2, and the structure was characterized by single-crystal X-ray technology. The adjacent NH4]VO(O2)2(ima)] monomers further constructed a 3-D supramolecular framework through intra- and intermolecular hydrogen bonding interactions. The composition of the title complex solution was explored using a combination of multinuclear (1H, 13C and 51V) magnetic resonance, heteronuclear single quantum coherence (HSQC), and variable temperature NMR in a 0.15 mol L?1 NaCl/D2O solution that mimics physiological conditions. According to NMR experimental results, a pair of isomers (Isomers A and B) are observed in aqueous solution, which are attributed to different types of coordination modes between the metal center and the ligands; Isomer B (the main product) has the same coordination structure as the crystal structure of NH4]VO(O2)2(ima)]. The 51V NMR experiment together with single-crystal X-ray diffraction results indicated that Isomer A is the hexa-coordinated peroxovanadium species while Isomer B is the hepta-coordinated species. |
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| Keywords: | NMR bisperoxovanadium imidazole-4-carboxamide crystal structure supramolecular framework |
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