THERMODYNAMIC STUDY OF THE COMPLEXATION OF SOME THIACROWN ETHERS AND IODINE MONOBROMIDE IN CARBON TETRACHLORIDE SOLUTION

摘要

Complexation of TT9C3, TT12C4 and HT18C6 as n-donor, with IBr as a-acceptor has been studied at different temperatures in carbon tetrachloride solution. Spectrophotometric measurements have been carried out to obtain the stoichiometry, the equilibrium constants and thermodynamic parameters. The equilibrium constants of the resulting 1: 1 complexes are calculated from the fitting of the absorbance mole ratio data in MATLAB software and found to vary in the order: HT18C6>TT9C3>TT12C4. The Delta H degrees, Delta S degrees and Delta G degrees values are obtained by the logK(f) vs. 1/T plots. All of the complexes are enthalpy stabilized and entropy destabilized. The contribution of various factors on Delta H degrees and Delta S degrees are discussed. The plot of T Delta S degrees vs. Delta H degrees is linear. The possible reasons for such linearity are discussed.