ESR Study of the Mechanism of an Intermolecular Cation-Exchange Reaction between 3,5-Dinitrobenzonitrile-Sodium Ion Pair and Sodium Tetraphenylborate

Analysis of the ESR spectra of 3,5-dinitrobenzonitrile-sodium in THF containing sodium tetraphenylborate indicates the formation of triple ions, which are the intermediates of an intermolecular cation-exchange reaction in which the incoming cation goes to the uncomplexed nitro group. The corresponding kinetic and thermodynamic parameters have been derived through a nonlinear least-squares line-shape fitting of the experimental ESR spectra followed by an accurate analysis of their temperature and concentration dependence. The spin distribution in both the ion pair and the triple ion has been computed by the McLachlan method modified according to McClelland. The transport properties of the system 3,5-dinitrobenzonitrile-sodium/THF/sodium tetraphenylborate have also been investigated. The possible use of the ionic aggregates of aromatic radical anions as spin probes in the study of concentrated solutions of electrolytes is investigated.