1. Solution studies of vanadium(IV) complexes with nitrilotriacetic acid (NTA) and other aminopolycarboxylic acids (NDAP, NDPA, and NTP).
- Author
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Araujo, ML, Brito, F, Cecarello, I, Guilarte, C, Martinez, JD, Monsalve, G, Oliveri, V, Rodriguez, I, and Salazar, A
- Subjects
VANADIUM ,CARBOXYLIC acids ,NITRILOTRIACETIC acid ,IONS ,RARE earth metals - Abstract
Complexes of vanadium(IV) with aminopolycarboxylic acids, nitrilotriacetic (NTA), nitrilodiaceticpropionic (NDAP), nitrilodipropionicacetic (NDPA), and nitrilotripropionic (NTP) acids were studied by electromotrice force measurements [emf(H)] in 3.0 M KCl ionic medium at 25°C. Data analysis using the least-squares program LETAGROP, according to the general reaction p H+ + q VO2+ + r C3- ⇆ Hp(VO)qCrp+2q-3r, indicates that the following complexes are formed (H3C ligands): NTA ([VOC]- and [OHVOC]2-); NDAP ([VOC]- and [OHVOC]2-); NDPA ([VOC]- and [OHVOC]2-); and NTP ([H2VOC]+, HVOC, [VOC]-, and [OHVOC]2-). The following order of coordination capacity NTA > NDAP > NDPA > NTP is suggested, based on values of stability constants and is attributed to the increase in propionic groups in the sequence. The study confirms that five-membered ring chelates are the most stable for VIV, like CuII, NiII, lanthanides, and other heavier elements. [ABSTRACT FROM AUTHOR]
- Published
- 2009
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