pH-metric, UV-Vis and 51V NMR study of vanadium(V) coordination to α-aminohydroxamic acids in aqueous solutions

被引：12
作者：
Miranda, C. T. [1 ]
Carvalho, S. [1 ]
Yamaki, R. T. [2 ]
Paniago, E. B. [1 ]
Borges, R. H. U. [1 ]
De Bellis, V. M. [1 ]
机构：
[1] Univ Fed Minas Gerais, Dept Chem, ICEx, Belo Horizonte, MG, Brazil
[2] Univ Estadual Sudoeste Bahia, Dept Chem, Jequie, BA, Brazil
来源：
POLYHEDRON | 2010年 / 29卷 / 02期
关键词：
Vanadium(V); alpha-Aminohydroxamic acid; NMR; Potentiometry; V-51; Speciation; SUBSTITUTED HYDROXAMIC ACIDS; DISSOCIATION-CONSTANTS KA; N-HYDROXYACETAMIDE; DELTA-HA; COMPLEXES; VANADATE; SPECTROSCOPY; DIPEPTIDES; CHEMISTRY; LIGAND;
D O I：
10.1016/j.poly.2009.10.020
中图分类号：
O61 [无机化学];
学科分类号：
070301 ; 081704 ;
摘要：
The full speciation of vanadium(V) complexation systems with glycinehydroxamic acid and three alpha-aminohydroxamic acids (alpha-alanine-, alpha-threonine- and alpha-lysine-) has been achieved using potentiometric and spectroscopic techniques. Formation constants were calculated in a systematic study at different concentrations and ligand-to-metal molar ratios. In each case, in a neutral medium, two complexes were identified with 1:1 and 1:2 metal-to-ligand ratios, both of which can either be protonated or deprotonated depending on the acidity or basicity of the medium. Structures are proposed based on V-51 NMR results. The 1:1 complex, VO2L (VO2+ = dioxovanadium(V) ion and L- = alpha-aminohydroxaniate ligand), has a distorted trigonal bipyramidal structure in neutral medium and it exists as VO2HL+ in acidic and as VO2(OH)L- in basic medium. The 1:2 complex, VO2H2L2+, which is formed in neutral medium, has an octahedral structure and also exists as VO2H3L22+ and VO2HL2, in acidic and basic media, respectively. In all cases, only the hydroxamate group appears to be coordinated to the VO2+ group. (c) 2009 Published by Elsevier Ltd.
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页码：897 / 903
页数：7
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