Intramolecular Charge-Transfer Interactions in Triplet Keto Sulfides

Article abstract of DOI:10.1021/ja00244a031

The photochemistry of β-,γ-and δ-phenacyl sulfides, sulfoxides, and sulfones has been studied.The first group undergoes no irreversible reaction.The other two undergo type II photoelimination but in low quantum efficiency.Analysis of triplet lifetimes and product quantum yields indicates that all undergo rapid internal quenching, which is ascribed to a charge-transfer (CT) process.The positional dependence of rate constants for this CT reaction is β > γ > α >> δ > ε .Some rate constants (units of 1E8 s^-1) for PhCO(CH2)_nSBu are as follows: n = 1, 16; n = 2, 55; n = 3, 29; n = 4 ,1.7; n = 5, PhS <*> BuS(O) >> BuS, BuSO2, CH3CO-S and range from 1E9-3*1E5 s^-1.Rate constants for triplet state γ-hydrogen abstraction were found to correlate well with the ?₁ values of the various sulfur groups, except for δ-sulfinyl, which apparently participates in the reaction.