The rate of back electron transfer following photoexcitation of ground-state complexes between ClO and aromatic molecules in nitrile solvents is examined. Both solvent effects on a single molecular complex and a series of complexes within a single solvent are analyzed in terms of commonly used theoretical models, For a single molecular complex (ClO-benzene), the rate of back electron transfer decreases with decreasing solvent dielectric constant and is temperature independent. This indicates that the reaction rate decreases with increasing exothermicity, behavior consistent with that expected for reactions in the Marcus inverted region. Investigation of the dependence of the reaction rate on exothermicity using a series of substituted benzenes as acceptor molecules in a single solvent revealed increasing reaction rates with increasing driving force, opposite to that observed upon varying solvent. Studies of deuteration effects on the reaction rate constant suggest that the origin of these disparate predictions arises from the assumptions made in carrying out the data analysis on the series of donor-acceptor complexes studied. In particular, both the inner-sphere and outer-sphere contributions to the reorganization energy are not constant for the set of molecules studied. This study demonstrates the difficulty in extracting accurate information on the reaction exothermicity, reorganization energy, and electronic coupling from measured rate constants.