J. Sanchiz, S. Domínguez, A. Mederos
Aug 27, 1997
Citations
1
Influential Citations
24
Citations
Journal
Inorganic Chemistry
Abstract
The coordinating ability of the ligands 3,4-toluenediamine-N,N,N‘,N‘-tetraacetic (3,4-TDTA), ortho-phenylenediamine-N,N,N‘,N‘-tetraacetic (o-PhDTA), and 4-chloro-1,2-phenylenediamine-N,N,N‘,N‘-tetraacetic (4-Cl-o-PhDTA) acids, H4L, with Cu(II) and Fe(III) is described. The stability constants and the partial molar enthalpies of the complexes formed (25 °C, I = 0.5 mol dm-3 in KNO3) were respectively determined by means of emf and calorimetry measurements. For the system 3,4-TDTA−Fe(III) (25 °C, I = 0.5 mol dm-3 in NaClO4), the stability constants of the complexes FeL- and [FeL(OH)]2- were also determined spectrophotometrically. The calorimetric measurements show that the complex formation is entropy driven, exothermic for Cu(II) and endothermic for Fe(III). The partial molar entropy of complexation (ΔS°) is much the same as that of the EDTA complexes. X-ray diffraction structural analysis of Na[Fe(4-Cl-o-PhDTA)(H2O)]·1.5H2O revealed that, in [FeL(OH2)]- (monoclinic C2/c, a = 10.693(3) A, b = 13.931(3) A, ...