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 I-2 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 + I-2 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 I-2 on a picosecond time scale. (c) 2008 Elsevier B. V. All rights reserved.