Publication
588
J. Phys.
Chem. A, 109 (12), 2984-2990,
2005
DOI: 10.1021/jp0442549 S1089-5639(04)04254-9
|
|
|
Sticky Dissociative Electron Transfer to
Polychloroacetamides. In-Cage Ion-Dipole Interaction Control through the Dipole
Moment and Intramolecular Hydrogen Bond
|
Cyrille Costentin, Cyril Louault, Marc Robert, and Anne-Lucie Teillout
Laboratoire d'Electrochimie
Moléculaire,
UMR 7591, Université Paris 7-CNRS, 2 place Jussieu, F-75251 Paris Cedex
05, France
The reductive cleavage of chloro- and polychloroacetamides in
N,N-dimethylformamide gives new insights into the nature of the
in-cage ion radical cluster formed upon dissociative electron transfer. Within
the family of compounds investigated, the electrochemical reduction leads to the
successive expulsion of chloride ions. At each stage the electron transfer is
concerted with the breaking of the C-Cl bond and acts as the rate-determining
step. The reduction further leads to the formation of the corresponding
carbanion with the injection of a second electron, which is in turn protonated
by a weak acid added to the solution. From the joint use of cyclic voltammetric
data, the sticky dissociative electron-transfer model and quantum ab initio
calculations, the interaction energies within the cluster fragments ( R,
Cl-) resulting from the first electron transfer to the parent RCl
molecule are obtained. It is shown that the stability of these adducts, which
should be viewed as an essentially electrostatic radical-ion pair, is mainly
controlled by the intensity of the dipole moment of the remaining radical part
and may eventually be strengthened by the formation of an intramolecular
hydrogen bond, as is the case with 2-chloroacetamide. |
