The temperature dependence of the triplet lifetimes of some aryl iodides and bromides

Abstract

A variable temperature pulse radiolysis study of the triplet state of iodonaphthalene and iodobiphenyl indicates that an intramolecular energy relocation process is inhibited as the temperature is lowered from 20°C, resulting in a lengthening of the lifetime of the triplet state. It is postulated that the triplet state energy of these aryl iodides is channeled into the C-I bond, causing bond dissociation. The activation energies for this process, in toluene, have been measured to be 5.9, 4.8, and 3.4 kcal/mole for 1-iodonaphthalene, 2-iodonaphthalene and 4-iodobiphenyl, respectively. Similar experiments with aryl bromides in toluene, at temperatures greater than 20°C, are also interpreted as..