Szilard-Chalmers Reactions in the Hexahalocomplexes of Iridium

Abstract

Thermal and radiation annealing have been studied in several hexahalocomplexes of tri-and tetravalent iridium. Moreover, transfer annealing experiments after recrystallization of irradiated samples were carried out. In all irradiated compounds a post-irradiation thermal treatment results in an increase of the retention. Heating of recrystallized irradiated samples produces effects which are similar to the thermal annealing effects. Hydration or dehydration of irradiated complexes affects the product spectra but does not result in an increase of the retention. The results are discussed in terms of a model which assumes that the annealing of some of the fragments present in the anhydrous complexes is triggered by an oxidation reaction with radiation-induced electron holes or V-centres. In a second step the fragments recombine with free ligands or they acquire ligands from IrCl e -2 ions by ligand transfer reactions. In hydrated and in recrystallized samples the annealing may largely be interpreted as exchange reactions which proceed via a ligand vacancy diffusion mechanism.Radiochim. Acta 17, 73 (1972). 12. W. J. VAN OOIJ and P. LIEBERMAN, unpublished results.