Intrinsic Reaction Parameters for Electron Transfer from Aromatic Radical Anions to Vicinal Dibromoalkanes in Alkane Solutions

Intrinsic Reaction Parameters for Electron Transfer from Aromatic Radical Anions to Vicinal Dibromoalkanes in Alkane Solutions Full article

Journal

Journal of Physical Chemistry A
ISSN: 1089-5639

Output data

Year: 2011, Volume: 115, Number: 35, Pages: 9861-9875 Pages count : 15 DOI: 10.1021/jp2040828

Authors

Ivanishko I.S. ¹ , Beregovaya I.V. ² , Hartmann S. ³ , Koehler W. ³ , Borovkov V.I. ^1,4

Affiliations

1	(Данные Web of science) Inst Chem Kinet & Combust SB RAS, Novosibirsk 630090, Russia
2	(Данные Web of science) NN Vorozhtsov Inst Organ Chem, Novosibirsk 630090, Russia
3	(Данные Web of science) Univ Bayreuth, Dept Phys, D-95440 Bayreuth, Germany
4	(Данные Web of science) Novosibirsk State Univ, Novosibirsk 630090, Russia

In diffusion-assisted bimolecular reactions, the elementary reaction mechanism is typically difficult to study, because the kinetics of the intrinsic reaction is masked by the diffusive motion of the reactants. One of the possible experimental approaches to solve the problem is the precise determination of the effective reaction radii, R = k/(4 pi Ds), where k is the stationary value of the reaction rate constant and D(s) is the sum of the diffusion coefficients of the reactants involved. In this work, this approach has been applied to study the reaction between radical anions of aromatic compounds (diphenylacetylene and diphenylsilane) and vicinal dibromoalkanes (1,2-dibromoethane and trans-1,2-dibromocyclohexane) in liquid alkanes. The reaction rates were determined using the effect that the bromoalkanes exert on the decay kinetics of the fluorescence from the irradiated solutions of the aromatics. The effect of the external electric field on the fluorescence decays was exploited to measure aromatic radical ion mobilities. Diffusion coefficients of the bromoalkane molecules were determined by means of the thermal diffusion forced Rayleigh scattering technique. The experimental radii obtained in the temperature range of 273-333 K were compared with those calculated from the diffusion equation with a distance-dependent relative diffusion coefficient and electron-transfer rate. The most important factors that have been taken into account are (i) the ion dipole interaction between the reagents, (ii) the shift of the equilibrium between rotational isomers of dibromoalkanes in the electric field of its charged partner, and (iii) the hydrodynamic interaction. The study shows that the apparent activation energy of the intrinsic electron-transfer rate from the anions to the dibromoalkanes does not exceed a few kilocalories per mole, in agreement with the results of quantum chemical calculations within the DFT aproach. The evaluated electron-transfer rates at: the reagents' contact (intrinsic rate) were estimated to be on the order 5 x 10 s(-1), corresponding to transfer matrix elements of about 30-50 cm(-1).

Ivanishko I.S. , Beregovaya I.V. , Hartmann S. , Koehler W. , Borovkov V.I.
Intrinsic Reaction Parameters for Electron Transfer from Aromatic Radical Anions to Vicinal Dibromoalkanes in Alkane Solutions
Journal of Physical Chemistry A. 2011. V.115. N35. P.9861-9875. DOI: 10.1021/jp2040828 WOS Scopus РИНЦ OpenAlex

Published online:	Aug 8, 2011
Published print:	Sep 8, 2011

Web of science:	WOS:000294385800011
Scopus:	2-s2.0-80052342558
Elibrary:	18003424
OpenAlex:	W2314725312

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