Natural logarithm of the reaction efficiencies for hydrogen-atom abstraction from fourteen different hydrogen-atom donors by N-(3-chloro-5-dehydrophenyl)pyridinium cation (l) versus the vertical ionization energies (eV) of the hydrogen-atom donors. The data are fit to a linear trend line (R2 = 0.95). The hydrogen-atom donors are: tributyltin hydride (Tri), benzeneselenol (Ben), proline (Pro), 2-deoxy-D-ribose (2-Deoxy), 1-O-methyl-2-deoxy-D-ribose (1-O-Meth), ribose (Rib), valine (Val), tetrahydrofuran (THF), L-alanine (Ala), glycine (gly), cyclohexane (cyclo), isopropanol (Iso) and ethanol (Eth).