Rates of the halide ion cleavage from halo-9,10-diphenylanthracene anion radicals in DMF

The rate constants k for the cleavage of the carbon-halogen bond in anion radicals of 1- and 2-chloro-9,10-diphenylanthracene, 9,10-dichloroanthracene and 2-bromo-9,10-diphenylanthracene have been determined and compared with the literature data for other anthracenyl halides. There is no significant correlation between log k and the formal potentials of the anion radical formation. However, linear relationships of the experimental RT In k vs. the relative thermodynamic contribution to the activation barrier as well as the relative intrinsic activation energy (calculated on the basis of the recent Savéant model and using the ionic component of the bond enthalpy estimated from the absolute electronegativity and hardness) have been found.