Determination of thermodynamic formation values for some solid charge-transfer complexes of iodine

Abstract

The standard Gibbs free energy, enthalpy, and entropy of complex formation of five solid molecular complexes of iodine have been determined by comparing the e.m.f.'s of galvanic cells having either solid iodine or the iodine complex as cathode. All of the complexes were found to have a negative enthalpy of formation, which was in the range −5 to −14 kJ mol −1, except for one very weak complex. The relative stability of the complexes was largely determined by the standard entropy of formation which varied from +18 J K −1 mol −1, for the most stable of the complexes studied, to −21 J K −1 mol −1.