Based on experimental observations and MO calcns. of the reactants, the SRN1 reactivity depended on the ease with which one electron could be added to RBr-LUMO (R = aryl). Excitation of the ground state charge-transfer complex from RBr and a carbanion might represent a significant fraction of the SRN1 photostimulation.

Key words: PHOTOCHEMICAL REACTION, REACTION MECHANISM, HALIDE, AROMATIC HYDROCARBON, COMPUTER APPLICATIONS, EXCITED STATE, ARGON, MOLECULAR ORBITAL THEORY, NUCLEOPHILIC REACTION, CHARGE TRANSFER COMPLEX