L. Crocker et al., ELECTRON-AFFINITIES OF SOME POLYCYCLIC AROMATIC-HYDROCARBONS, OBTAINED FROM ELECTRON-TRANSFER EQUILIBRIA, Journal of the American Chemical Society, 115(17), 1993, pp. 7818-7822
The gas-phase electron attachment free energies DELTAG(a)degrees, wher
e-DELTAG(a)degrees almost-equal-to EA, were measured for several polyc
yclic aromatic hydrocarbons with the electron-transfer equilibria tech
nique. The EA values in kcal/mol are as follow: anthracene, 13.2; benz
[a]pyrene, 18.2; perylene, 22.3; tetracene, 23.9; and pentacene, 31.2.
These results, when combined with the literature value for naphthalen
e, -4.4 kcal/mol, based on electron transmission spectroscopy, lead to
an approximately linear correlation with the one-electron (polarograp
hic) reduction potentials determined in solution. However, the slope o
f the line is not equal to 1 as previously assumed. The deviation from
unity is probably due to decreases of the solvation exothermicity of
the radical anions, expected because of the increasing charge delocali
zation for the negative ion with increasing electron affinity of the n
eutral precursor.