Erratum: Dynamics of reversible electron transfer reactions [J. Chem. Phys. 95, 3325 (1991)] (original) (raw)
Kinetics and mechanism of electron transfer reactions
2000
The kinetics of oxidation of ketones by thallium (III) has been studied in acid perchlorate medium. The reaction does not indicate enolization to be the rate controlling step in the reaction mechanism. The kinetic rate law (1) has been observed. Where K h is the hydrolysis constant of the oxidant. A plausible reaction mechanism is suggested conforming to the rate law (1). Activation parameters were evaluated.
Diffusion, spin and reaction control in geminate reverse electron transfer
Physical Chemistry Chemical Physics, 2001
Kinetic analyses of geminate radical escape yields in terms of a simple ("" exponential ÏÏ) reaction scheme with Ðrst-order rate constants of separation and geminate recombination have been widely used in the literature, e.g. to evaluate rate constants of reverse electron transfer
An integral equation approximation for the dynamics of reversible electron-transfer reactions
The Journal of Chemical Physics, 1993
The solution to an integral equation [J. Zhu and J. C. Rasaiah, J. Chem. Phys. 96, 1435 (1992)] for the survival probabilities in the Sumi–Marcus model of reversible electron-transfer (ET) reactions, in which ligand vibrations and fluctuations in the solvent polarization play important roles, is obtained numerically using a simple computer program suitable for use on a PC. The solutions depend on the time correlation function Δ(t) of the reacting intermediates along the reaction coordinate which is shown to be equal to the time correlation function of the Born free energy of solvation of these intermediates even in discrete molecular solvents provided its response is linear. This enables Δ(t) to be determined accurately from time-delayed fluorescence Stokes shift experiments or from dynamical theories of ion solvation; it is usually an exponential (Debye solvent) function of time or a sum of such exponentials (non-Debye solvent). The solutions to the integral equation, which can be ...
Aquatic Geochemistry, 2010
In the aquatic geochemical literature, a redox half-reaction is normally written for a multi-electron process (n [ 2); e.g., sulfide oxidation to sulfate. When coupling two multi-electron half-reactions, thermodynamic calculations indicate possible reactivity, and the coupled half-reactions are considered favorable even when there is a known barrier to reactivity. Thermodynamic calculations should be done for one or two-electron transfer steps and then compared with known reactivity to determine the rate controlling step in a reaction pathway. Here, thermodynamic calculations are presented for selected reactions for compounds of C, O, N, S, Fe, Mn and Cu. Calculations predict reactivity barriers and agree with one previous analysis showing the first step in reducing O 2 to O 2 with Fe 2? and Mn 2? is rate limiting. Similar problems occur for the first electron transfer step in these metals reducing NO 3 -, but if reactive oxygen species form or if two-electron transfer steps with O atom transfer occur, reactivity becomes favorable. H 2 S and NH 4
Reaction coordinates for electron transfer reactions
The Journal of Chemical Physics, 2008
The polarization fluctuation and energy gap formulations of the reaction coordinate for outer sphere electron transfer are linearly related to the constant energy constraint Lagrangian multiplier m in Marcus’ theory of electron transfer. The quadratic dependence of the free energies of the reactant and product intermediates on m and m+1, respectively, leads to similar dependence of the free energies on the reaction coordinates and to the same dependence of the activation energy on the reorganization energy and the standard reaction free energy. Within the approximations of a continuum model of the solvent and linear response of the longitudinal polarization to the electric field in Marcus’ theory, both formulations of the reaction coordinate are expected to lead to the same results.
Solvent dynamical effects on electron transfer reactions
The Journal of Chemical Physics, 1994
An integraI equation [Rasaiah and Zhu, J. Chem. Phys. 98, 1213 (1993)] for the survival probabilities of electron transfer (ET) between thermally equilibrated reactants in solution is extended to include quantum effects on the ligand vibration and ET from a nonequilibrium initial state. We derive the kernel of the integral equation using a Green's function technique and demonstrate that it is determined by the solvent dynamics, the relative contributions of ligand and solvent reorganization energies, and the barrier heights for electron transfer. The extension of the theory to ET from a nonequilibrium initial state modifies the integral equation to provide the survival probabilities for the reactants that are not necessarily kinetically of first order, but can be directly compared with experiment. The long time rate, however, shows a simple exponential time dependence that is analyzed in terms of a rate constant with a diffusive' solvent controlled component and a remainder. .The effect of solvent dynamics on the diffusive part is governed by the same factors that determine the kernel. We find that the fast diffusive mode (small relaxation time) affects the rate of ET reactions with high barriers, while the slow diffusive part (large relaxation times) influences the rate when the barriers are low. Quantum corrections to these effects are calculated using the semiclassical approximation. The theory is used to analyze the ET kinetics of betaine-30 in glycerol triacetate (GTA) over a 100" temperature range and the influence of the details of solvent dynamics on the rates of-electron transfer is elucidated. An appendix discusses improved saddle point approximations for the rates of electron transfer reactions calculated using the golden rule. 0 I994 American Institute of Physics.
Application of electron-transfer theory to excited-state redox processes
Chemical Physics Letters, 1979
Rtxx&& 5 September 1978 @uenchiq mte corutmts have been obtained for oxidative electron transfer quenching of Ru(bpy)z+* by a series of nitroaromxic and bipq ridinium quenchers and reductive qucnchinz by d series of somatic amines. The results are cwsistent r<Ml electron-transfer thtxxy x\hen competing prorrsses 1% hich occur foIIo\\ing the electron-transfer quenching step are taken into zccount. The competing processes arc back4ea_tron-tmmfrr to give the excited state Ru(bpy)z** and net quenchiq b> the sum of r&ox-pioduct-separtion and back-electron-transfer to gixe Ru(bp))z*_
Angewandte Chemie, 1988
The Intersecting-State Model (ISM) is used to calculated the absolute rate constants of self-exchange electron-transfer reactions (ET) of organic species. The systems studied include aromatic hydrocarbons, quinones, nitrobenzene, aromatic nitriles, tetracyanoethylene, aromatic amines, and alkylhydrazines. Ali of the calculated rates are within one order of magnitude of the experimental ones, and the correlation coefficient between the two sets is 0.96. An electron-tunneling model has been developed to calculate distance-dependent nonadiabatic factors of intramolecular ET. This model can be used with ISM to calculate intramolecular ET rates. The system biphenylyl-spacer-naphthyl in tetrahydrofuran, whose distance-dependent intramolecular rates were measured by Closs and Miller, was used to test our calculations, because its ET rates can be calculated without adjustable parameters. Our absolute rate calculations are in an order-of-magnitude agreement with the experimental ones.
Nucleophilic Substitution Reactions by Electron Transfer
Chemical Reviews, 2003
is a Scientist Researcher of CONICET (National Research Council of Argentina) and a member of the National Academy of Science of Argentine. His current research interests include the reaction of radicals with nucleophiles, the chemistry of radical anions, electron transfer, organometallic chemistry, and transition metal catalyzed reactions. Adriana B. Pierini was born in 1953, also in Córdoba, and graduated as Licenciada in Organic Chemistry in 1974 from the Faculty of Chemical Sciences with honors. In 1979 she received the Ph.D. degree in Chemical Sciences from the same university under the supervision of Professor Roberto A. Rossi. She was a postdoctoral fellow from 1979 to 1981 with Professor M. J. S. Dewar at the University of Texas at Austin. Her main field of research is physical organic chemistry and computational organic modeling. Since 1996 she has been a full professor at the National University of Córdoba and a Scientist Researcher of CONICET (National Research Council of Argentina). Alicia B. Peñéñory was born in Córdoba in 1958. She received her undergraduate degree with first class honors from the National University of Córdoba in 1980. She received her Ph.D. degree in Chemical Sciences from the same university in 1986, where she carried out studies on the S RN 1 mechanism under the direction of Professor Roberto A. Rossi. She performed postdoctoral studies at Dortmund University and Würzburg University under the supervision of Professor W. P. Neumann and Professor W. Adam, on radical chemistry and photoinduced electron transfer process, respectively. She joined the National University of Córdoba as assistant professor in 1991, where she is presently associate professor and a Scientist Researcher of CONICET (National Research Council of Argentina). Her research interests include photochemical and chemical electron transfer chemistry, radical ions, reactivity and mechanism studies, and synthetic applications of the ET process and enzymatic oxidation.