Cyanobenzyl and chlorobenzyl radicals via anion photoelectron imaging spectroscopy

We report the adiabatic electron affinity of the cyanobenzyl radical, EA(PhCHCN) = 1.90 ± 0.01 eV, determined from a combination of the experiment and theory, and assign an upper limit of the EA for the chlorobenzyl radical, EA(PhCHCl) ≤ 1.12 eV. From these results, the C-H bond dissociation energies at the benzyl-α sites of the corresponding closed-shell parent molecules are determined: 80.9 ± 2.3 kcal mol^-1 for benzyl nitrile and an upper limit of 84.2 kcal mol^-1 for benzyl chloride. These results are discussed in terms of substituent interactions and in relation to other similar molecules.