Oxovanadium(IV) complexes of quinic acid. Synthesis, characterization and potentiometric study, Y. Allegretti, E. G. Ferrer, A. C. González Baró and P. A. M. Williams

Y. ALLEGRETTI; E. G. FERRER; A. C. GONZÁLEZ BARO; P. A. M. W ILLIAMS

POLYHEDRON

Año: 2000 vol. 19 p. 2613 - 2619

0277-5387

The synthesis, characterization and speciation of the VO2–quinic acid system is described. Three new solid complexes were obtained: [VO(quin)(H2O)3] (I), Na4[VO(quin)2SO4]·4H2O (II) and Na6[VO(quin)2SO4]·4H2O (III), at pH 3.5, 6 and 12, respectively. They were characterized by elemental analysis, diffuse reflectance, FTIR and Raman spectroscopies, and thermal behavior. Their stability constants were determined at 298 K and at a constant ionic strength of 0.150 M using potentiometric methods. In aqueous solution three different complexes appeared as the main species at the pH values indicated above as shown in the species distribution curves. Up to pH 8 the system behaves as a 2-hydroxyacid:metal-like compound, while at higher pH further deprotonations were observed, which resulted in the formation of sugar–VO2-like complexes. UV–Vis spectra were also reported. reported. further deprotonations were observed, which resulted in the formation of sugar–VO2-like complexes. UV–Vis spectra were also reported. reported. respectively. They were characterized by elemental analysis, diffuse reflectance, FTIR and Raman spectroscopies, and thermal behavior. Their stability constants were determined at 298 K and at a constant ionic strength of 0.150 M using potentiometric methods. In aqueous solution three different complexes appeared as the main species at the pH values indicated above as shown in the species distribution curves. Up to pH 8 the system behaves as a 2-hydroxyacid:metal-like compound, while at higher pH further deprotonations were observed, which resulted in the formation of sugar–VO2-like complexes. UV–Vis spectra were also reported. reported. further deprotonations were observed, which resulted in the formation of sugar–VO2-like complexes. UV–Vis spectra were also reported. reported. obtained: [VO(quin)(H2O)3] (I), Na4[VO(quin)2SO4]·4H2O (II) and Na6[VO(quin)2SO4]·4H2O (III), at pH 3.5, 6 and 12, respectively. They were characterized by elemental analysis, diffuse reflectance, FTIR and Raman spectroscopies, and thermal behavior. Their stability constants were determined at 298 K and at a constant ionic strength of 0.150 M using potentiometric methods. In aqueous solution three different complexes appeared as the main species at the pH values indicated above as shown in the species distribution curves. Up to pH 8 the system behaves as a 2-hydroxyacid:metal-like compound, while at higher pH further deprotonations were observed, which resulted in the formation of sugar–VO2-like complexes. UV–Vis spectra were also reported. reported. further deprotonations were observed, which resulted in the formation of sugar–VO2-like complexes. UV–Vis spectra were also reported. reported. respectively. They were characterized by elemental analysis, diffuse reflectance, FTIR and Raman spectroscopies, and thermal behavior. Their stability constants were determined at 298 K and at a constant ionic strength of 0.150 M using potentiometric methods. In aqueous solution three different complexes appeared as the main species at the pH values indicated above as shown in the species distribution curves. Up to pH 8 the system behaves as a 2-hydroxyacid:metal-like compound, while at higher pH further deprotonations were observed, which resulted in the formation of sugar–VO2-like complexes. UV–Vis spectra were also reported. reported. further deprotonations were observed, which resulted in the formation of sugar–VO2-like complexes. UV–Vis spectra were also reported. reported.