M.V. Sangaranarayanan

The title compound, C6H2BrCl2I, crystallizes in space group P21/c with two molecules in the asymmetric unit. The molecules stack in two different directions, with their plane normals approximately parallel to [110] and [11̄0]. The molecules of the asymmetric unit are held together by π-π interactions. © 2004 International Union of Crystallography Printed in Great Britain - all rights reserved.

Electrochemical reduction of 4′-bromomethylbiphenyl-2-carbonitrile at glassy carbon electrodes is studied wherein the cleavage of carbon-bromine bond occurs in a single step in general. With increase in the driving force of the reaction, an unusual bell-shaped variation of the transfer coefficient with logarithmic scan rate has been observed, indicating the possibility of radical anion of 4′-bromomethylbiphenyl-2-carbonitrile as the intermediate. The finer details of the reduction have been studied by the convolution analysis of the voltammetric data and the reorganization energy of the reaction obtained at higher scan rates establishes the formation of radical anion of 4′-bromomethylbiphenyl-2-carbonitrile. © 2005 Elsevier B.V. All rights reserved.

A simple analytical expression for the current function has been formulated for irreversible electron transfer processes in linear sweep voltammetry (LSV). The equations pertaining to the surface concentrations of the reactants and products have been obtained using the current function. The parametric dependence of the diffusion layer thickness has also been derived and its significance pointed out. The reductive cleavage of carbon tetrachloride in N,N′-dimethylformamide (DMF) at glassy carbon electrodes is investigated for verifying the theoretical expressions. © 2004 Elsevier Ltd. All rights reserved.

Electrochemical reductive cleavage of carbon tetrachloride at glassy carbon electrodes in various non-aqueous solvents follows a quadratic activation-driving force dynamics whereas the Butler-Volmer kinetics is observed in the case of benzonitrile. A relatively higher transfer coefficient value has been noticed in benzonitrile, while in rest of the solvents, the transfer coefficients are less than 0.5. In benzonitrile, both the electron transfer and bond cleavage occur in a single step with a linear activation-driving force relationship, as deduced from the low temperature voltammetric studies in conjunction with the convolution analysis. © 2004 Elsevier B.V. All rights reserved.

The electrochemical reduction of carbon-halogen bonds in 5-bromo-1,3-dichloro-2-iodobenzene follows quadratic activation-driving force relationship except in one of the carbon-chlorine bonds. The variation of the transfer coefficient with the electrode potential has been estimated using the voltammetric data coupled with the convolution analysis. The standard potentials pertaining to the reduction of carbon-halogen bonds are evaluated using the Marcus theory of outer sphere electron transfer. © 2004 Elsevier Ltd. All rights reserved.

The electrochemical reductive cleavage of the carbon-iodine bond in 5-bromo-1,3-dichloro-2-iodobenzene has been analyzed from the mechanistic point of view employing the Marcus theory of heterogeneous outer sphere electron transfer. The variation of the electrochemical transfer coefficient with potential has been estimated from the cyclic and convolution voltammetric studies. The comparison of the experimental reorganization energy with the theoretical predictions has revealed the existence of the radical anion of 5-bromo-1,3-dichloro-2-iodobenzene as a transient species. © 2004 Elsevier Ltd. All rights reserved.

The title compound, C6H4BrCl2N, crystallizes in the space group P21/c with two molecules in the asymmetric unit. Molecules related by an a-axis translation are slacked over each other, bound by π-π interactions. Molecules in adjacent stacks are linked to each other through weak N - H⋯N hydrogen bonds. © 2005 International Union of Crystallography Printed in Great Britain - all rights reserved.

The electrochemical reductive cleavage of carbon-chlorine bond in 1-chloro-2,4-dinitrobenzene at gold electrodes is analyzed from a mechanistic point of view. The initial electron transfer forms the radical anion of 1-chloro-2,4-dinitrobenzene which subsequently undergoes bond cleavage following an EC mechanism. At low scan rates, the reduction is under the kinetic control by the chemical step, while the voltammetric wave becomes reversible at high scan rates and a mixed chemical-diffusion control is observed at intermediate scan rates. The cleavage rate constant of the carbon-chlorine bond has been deduced using the voltammetric data in conjunction with convolution analysis and the results have been verified by simulating the experimental voltammogram under the frame work of EC mechanism. © 2005 Elsevier Ltd. All rights reserved.

A concerted dissociative electron transfer mechanism has been observed in the electrochemical reduction of carbon tetrachloride in N,N′-dimethyl formamide (DMF) - water binary solvent. The kinetics of the process deviate from Butler-Volmer kinetics with a linear dependence of the transfer coefficient on the potential. The standard electrode potentials of the process in various compositions of the binary mixture have been estimated using the voltammetric data coupled with convolution analysis and are in agreement with independent theoretical calculations. The variation of the transfer coefficient with the composition of the binary mixture has led to the investigation of the problem based on Marcus-Savéant dissociative electron transfer theory and the solvent reorganization energies for various compositions of the binary mixture have been evaluated using the above analysis. © 2004 Elsevier B.V. All rights reserved.