Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
1244278 | Talanta | 2007 | 16 Pages |
Abstract
Calorimetric measurements were carried out following similar procedures and in the same experimental conditions as employed for the potentiometric measurements at I = 1.0 mol Lâ1 in NaCl. The stability of UO22+-oxalate2â complexes is fairly high and their main contribution to stability is entropic in nature. Some linear empirical relationships were found which make it possible to calculate (i) the contribution of a single bond: ÎGsb°=â16.6±0.2kJmolâ1 and TÎSsb°=16.2±0.5kJmolâ1; (ii) chelate stabilisation per ring: ÎGr°=â1.30±0.04kJmolâ1 and TÎSr°=1.27±0.23kJmolâ1 and (iii) the mean stability of negatively charged Na+-ion pair complexes: logTK = (0.46 ± 0.02)·|z| (z = charge of complex species), ÎG° = â(2.60 ± 0.1)·|z| kJ molâ1 and TÎS° = 2.5 ± 0.5 kJ molâ1. Both potentiometric and calorimetric results provide evidence of the penta-coordination of the species UO2(ox)34â. SIT parameters were calculated from the data at I = 0 and I = 1.02 mol kgâ1. Comparisons are made with literature data. An insoluble dioxouranium(VI) ternary complex was synthesised (at I = 1.0 mol Lâ1 in NaCl) and characterised by thermoanalysis and elemental analysis.
Related Topics
Physical Sciences and Engineering
Chemistry
Analytical Chemistry
Authors
Francesco Crea, Alessandro De Robertis, Concetta De Stefano, Silvio Sammartano,