{"title":"51V-NMR investigation on the formation of peroxo vanadium complexes in aqueous solution: Some novel observations","authors":"Valeria Conte, Fulvio Di Furia, Stefano Moro","doi":"10.1016/0304-5102(94)00149-9","DOIUrl":null,"url":null,"abstract":"<div><p>Depending on the experimental conditions either monoperoxo or diperoxo vanadium complexes are formed in acid aqueous solutions by addition of H<sub>2</sub>O<sub>2</sub> to NH<sub>4</sub>VO<sub>3</sub>. The <sup>51</sup>V-NMR spectra of both species have been registered at different pH values. While the signal of the monoperoxo derivative is unchanged in the pH range 0–4, the chemical shift of the diperoxo species shows a continuous variation in the same interval thus suggesting the occurrence of a protonation equilibrium leading to a neutral diperoxo vanadium complex. In the presence of bidentate ligands L, e.g., picolinic or pyrazinic acid, under otherwise identical experimental conditions, complexed peroxo vanadium species are formed. The association equilibria can be conveniently studied by <sup>51</sup>V-NMR spectroscopy. Thus, different species, e.g., VO(O<sub>2</sub>)L, [VO(O<sub>2</sub>)L<sub>2</sub>]<sup>−</sup>, [VO(O<sub>2</sub>)<sub>2</sub>L]<sup>2−</sup> as a function of the pH has been detected and the corresponding association constants have been measured.</p></div>","PeriodicalId":16567,"journal":{"name":"分子催化","volume":null,"pages":null},"PeriodicalIF":0.0000,"publicationDate":"1994-12-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/0304-5102(94)00149-9","citationCount":"51","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"分子催化","FirstCategoryId":"1089","ListUrlMain":"https://www.sciencedirect.com/science/article/pii/0304510294001499","RegionNum":0,"RegionCategory":null,"ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q4","JCRName":"Chemical Engineering","Score":null,"Total":0}
引用次数: 51
Abstract
Depending on the experimental conditions either monoperoxo or diperoxo vanadium complexes are formed in acid aqueous solutions by addition of H2O2 to NH4VO3. The 51V-NMR spectra of both species have been registered at different pH values. While the signal of the monoperoxo derivative is unchanged in the pH range 0–4, the chemical shift of the diperoxo species shows a continuous variation in the same interval thus suggesting the occurrence of a protonation equilibrium leading to a neutral diperoxo vanadium complex. In the presence of bidentate ligands L, e.g., picolinic or pyrazinic acid, under otherwise identical experimental conditions, complexed peroxo vanadium species are formed. The association equilibria can be conveniently studied by 51V-NMR spectroscopy. Thus, different species, e.g., VO(O2)L, [VO(O2)L2]−, [VO(O2)2L]2− as a function of the pH has been detected and the corresponding association constants have been measured.