Moreover, path C and path D also branch off from D, in the presence of a hydroxyl radical (generated in path B). Depending on the orientation of the two radicals in the encounter structure, path C can be followed, through the F1 MECP spin crossover point (second HAT). This presents a barrier of ΔG ‡ = 10.8 kcal/mol and results in the F1 product, as it transitions into the singlet spin state. Alternatively (path D), a different orientation of the hydroxyl radical pushes the structure into forming a diol. The spin transition barrier for Diol MECP is ΔG ‡ = 11.5 kcal/mol. Once on the singlet surface, Diol is created (ΔG = -36.7 kcal/mol). This is subsequently followed by a scrambling reaction with a barrier of ΔG ‡ = 18.5 kcal/mol, that has an equal probability of resulting in F1 (labelled benzaldehyde) or F2 (non-labelled benzaldehyde). The cumulative barrier for this path is ΔG ‡ = 25.4 kcal/mol.