Mv. Vener et al., THEORETICAL-STUDY OF HOMOGENEOUS ELECTRON SELF-EXCHANGE IN POLAR AROMATIC-MOLECULES - THE ROLE OF THE REACTANT STRUCTURE, Journal of electroanalytical chemistry [1992], 370(1-2), 1994, pp. 33-39
The solvent reorganization energies lambda0 of the electron self-excha
nge reaction between neutral molecules (nitrobenzene, its five para-su
bstituted derivatives and benzonitrile) and the corresponding radical
anions are discussed in terms of the Kirkwood approach combined with a
semi-empirical calculation of the reactant structure (AMI and interme
diate neglect of differential overlap (INDO) methods). The theoretical
values of lambda0 are compared with the experimental reorganization e
nergies lambda calculated from the Marcus equation and the homogeneous
rate constants k(ex). It is found that the values of lambda0 obtained
using the INDO method are approximately equal to the experimental lam
bda, whereas the AMI method gives poor results for para-substituted ni
trobenzenes. The linear correlation of log k(ex) with a(N)2 where a(N)
is a nitrogen coupling constant, established for para-substituted nit
robenzenes is interpreted. A simple criterion for slow electron transf
er of an arbitrary flat polar arene is formulated in terms of the reac
tant structure and the model of the ''specifying group'' suggested ear
lier by some of the authors.