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https://hdl.handle.net/10316/5233
Título: | Peroxovanadium(V) complexes of glycolic acid as studied by NMR spectroscopy | Autor: | Justino, Licínia L. G. Ramos, M. Luísa Caldeira, M. Madalena Gil, Victor M. S. |
Palavras-chave: | Peroxovanadium(V) complexes; Glycolic acid; Multinuclear NMR | Data: | 2000 | Citação: | Inorganica Chimica Acta. 311:1-2 (2000) 119-125 | Resumo: | Multinuclear (1H, 13C, 17O, 51V) 1D and 2D NMR spectroscopy has been used to characterize the peroxovanadium(V) complexes of glycolic acid in aqueous solution. One 2:2:2 (metal:ligand:peroxo) complex, together with a 1:1:1 and a 2:2:1 species, are found in the pH range 1-7. The 2:2:2 complex is a monoperoxo (one peroxide unit per vanadium atom) dinuclear species having a V2O3 4+ seven-coordinated metal centre. In this structure, the two vanadium atoms are triple bridged, two of those bridges being formed by oxygen atoms of the hydroxyl group of the acid. The 1:1:1 species has a seven-coordinated VO3+ metal centre. Glycolic acid bonds to the vanadium atoms in a bidentate way, through both the carboxylic and the hydroxyl groups. The peroxo groups are bound in the equatorial plane relative to the apical V=O and the geometry around each vanadium atom is close to pentagonal bipyramidal. The 2:2:1 complex is similar to the 2:2:2 species, except for one of the vanadium centres, which is now a five-coordinated oxovanadium centre. Three additional complexes are found in very small amounts for some pH and concentration conditions. Further support for the proposal of monoperoxovanadium species is given by UV-visible spectroscopy results. | URI: | https://hdl.handle.net/10316/5233 | Direitos: | openAccess |
Aparece nas coleções: | FCTUC Química - Artigos em Revistas Internacionais |
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