Knowledge Bank

The photochemical reaction pathways following the promotion of CF$2$I$2$ and CH$2$I$2$ into their lowest lying electronically excited states are reported. The pathways are mapped using the complete active space self-consistent field (CASSCF) method. The S$0$ to S$1$ transitions in both molecules are found to be n to sigma* type transitions. The relaxation of the electronically excited CF$2$I$2$* and CH$2$I$2$* molecules from the initially excited Frank-Condon (FC) region to the product wells on the ground-state potential energy surface are found to occur via conical intersections. The results from our computational investigations explain the selectivity of photoproduct formation previously observed in gas-phase experiments on one hand, where some obvious conclusions about the condensed-phase photochemistry of these molecules can also be drawn.