9307956 Maslak A study of mesolysis will be undertaken, which is the cleavage of radical ions to radicals and ions. The relationship between activation energy for mesolytic reactions and the free energy change for different modes of bond rupture and electron apportionment to products will be explored. The project will include probing solvent effects and ion pairing as well as a search for a Marcus-type inverted region for highly exergonic reactions. Redox potentials of radicals, ions, and radical ions will be measured by several methods and used to develop an empirical relation to evaluate redox potentials that are necessary to calculate thermodynamic quantities of mesolytic reactions. A unifying theoretical treatment of unimolecular dissociation reactions in solution will be developed from these results, where the goal is a master equation that governs these reactions. Mesolysis will also be studied by semiempirical and ab initio molecular calculations in order to evaluate pertinent stereoelectronic and charge delocalization aspects. %%% This grant from the Organic Dynamics Program supports the continuing work of Professor Przemyslaw B. Maslak at Pennsylvania State University. Bond breaking in molecules that contain either a positive or negative charge and a radical center (an unpaired electron on an atom) will be studied. The effect of solvent and pairing of these radical ions will be considered in this study as well as special effects when the reaction is highly favored. The energetics of transferring an electron to or from radical ions, radicals, and ions will be determined and these data will be correlated with the rate of bond breaking of the radical ions to give a master equation that governs these reactions. ***
