Reductive Cleavage of Carbon Tetrachloride in a Polar Solvent. An Example of a Dissociative Electron Transfer with Significant Attractive Interaction between the Caged Product Fragments

Abstract

The electrochemical reduction of carbon tetrachloride in N,N′-dimethylformamide follows a mechanism in which electron transfer and bond cleavage are concerted, at least at low and moderate driving forces. A detailed analysis of the kinetics of the reductive cleavage reveals that a small but significant interaction between the Cland Cl 3 C • fragments exists in the product state and is responsible for a strong acceleration of the reaction. An extension of the theory of dissociative electron transfer is proposed to rationalize the kinetic results and estimate the magnitude of the interaction energy. The model explains how a relatively small interaction energy results in a substantial acceleration of the reaction, caused by both an increase of the driving force and a decrease of the intrinsic barrier. Due to the strong polarization of the CCl 3 radical, the reaction is a particularly clear example of the possibility that attractive interactions between fragments survive in a polar solvent. Another attractive feature of this example is that CCl 4 is small enough a molecule for the application of ab initio techniques, with electron correlation implementation, to be applicable, serving as a complement to the semiempirical model describing the effect of interactions between product fragments on the dynamics of dissociative electron-transfer reactions.

pH dependent kinetic insights of electrocatalytic arsenite oxidation reactions at Pt surface

“…Marcus theory was originally formulated to address outer sphere electron transfer reactions, in which the electron donor and acceptor species only change their charge with an electron jumping (e.g., the oxidation of an ion like Fe 2+ /Fe 3+ ), but do not undergo large structural changes [33][34][35][36][37][38]. However, in agreement with Marcus theory of nonlinear dependency of activation free energy on reaction free energy, in the present case, it could be assumed that arsenite oxidation process occurred following a stepwise mechanism at pH3 and 5.…”

Regioselective electrochemical reduction of 2,4-dichlorobiphenyl – Distinct standard reduction potentials for carbon–chlorine bonds using convolution potential sweep voltammetry

“…The estimation of the standard reduction potentials (E 0 ) of organic compounds can be carried out using (i) thermochemical cycles [15] if concerted mechanism is valid; (ii) by analyzing the reversible anodic peak obtained at ultramicroelectrodes at high scan rates [16] and (iii) from variation of the transfer coefficients. We employ here, the parametric relation governing the transfer coefficient and intrinsic barrier (DG # 0 ) viz.…”

Application of the dissociative electron transfer theory and its extension to the case of in-cage interactions in the electrochemical reduction of arenesulfonyl chlorides

“…[28][29][30][31][32] While the accuracy of this model has been demonstrated through its application to heterogeneous [28][29][30][31][32][33][34] as well as homogeneous 35,36 ET reactions, examples undergoing this type of reduction mechanism are very limited. The examples known so far include carbon tetrachloride, 28,29 4-cyanobenzyl chloride, 29 haloacetonitriles, 30 polychloroacetamides, 31 benzyl thiocyanates, 33 and sulfenyl chlorides. 34 Additional experimental examples involving the intermediate formation of such radical-ion pairs (s--radical ions) would provide more insights into the factors controlling such phenomenon as well as into its consequences on chemical reactions.…”

“…The factors controlling the ET mechanism variation as well as the extend of the in-cage interactions between the reduction fragments are discussed on the basis of the dissociative ET theory and its extension to the case of in-cage interactions (''sticky'' dissociative ET). [28][29][30][31][32][33][34]64 Theoretical calculations help rationalize both the difference in the ET mechanism as well as the cluster formation. Electrochemical measurements were conducted in three electrode glass cells, thermostatted at 25 1C, and under dry nitrogen.…”