Direct Detection of Ion Pair Formation and Collapse in a Migration Reaction of a β-Phosphate Radical

In solutions of trifluorotoluene or toluene containing 2,2,2-trifluoroethanol, the β-phosphate radical heterolyzed to give a detectable ion pair, identified as a solvent-separated species. Rate constants for the radical fragmentation reaction forming the ion pair, for ion pair collapse, and for diffusive escape to free ions were measured. The kinetics and entropy of activation for fragmentation indicate that the rearrangement reaction occurs by a heterolysis pathway in all solvents.