Switching on molecular iodine elimination through isomerization: The F2C–I–I isomer of difluorodiiodomethane

We report a UMP2/LANL2MB computational investigation of the ground-state pathways involved in the 350-nm photoinduced formation of molecular iodine from difluorodiiodomethane. Formation of I2 from the conventional CF2I2 isomer is highly endothermic proceeding through a cyclic-skewed transition state at 62.4 kcal mol−1 above CF2I2. A minimum corresponding to iso-difluorodiiodomethane (F2C–I–I) is calculated at 24.8 kcal mol−1 above CF2I2. The formation of CF2 + I2 from F2C–I–I is endothermic by only 18.8 kcal mol−1. The results suggest that solvent-induced geminate recombination of CF2I and I photofragments leads to hot F2C–I–I, which dissociates to form I2 on a picosecond time scale.