Dogonadze

The Chemical Phy.dcs of Solvation Part A Theory of Solvation R. R. Dogonadze, E. Kalman, a. A. Koiiiyshev, J. Ulstrup, Eds., Elsevier, Amsterdam (1985). 

While being very similar in the general description, the RLT and electron-transfer processes differ in the vibration types they involve. In the first case, those are the high-frequency intramolecular modes, while in the second case the major role is played by the continuous spectrum of polarization phonons in condensed 3D media [Dogonadze and Kuznetsov 1975]. The localization effects mentioned in the previous section, connected with the low-frequency part of the phonon spectrum, still do not show up in electron-transfer reactions because of the asymmetry of the potential. 

R. Dogonadze and Yu. Chizmadjev, Dokl. Akad. Nauk. SSSR 157 (1964) 944. 

The second important point is common for all charge-transfer reactions. The proton is a charged particle, and as such, interacts strongly with solvent polarization. The first model taking into account botfi tfiese points was proposed by Dogonadze et al. (1967). 

Figure 2.1 (Plate 2.1) shows a classification of the processes that we consider they aU involve interaction of the reactants both with the solvent and with the metal electrode. In simple outer sphere electron transfer, the reactant is separated from the electrode by at least one layer of solvent hence, the interaction with the metal is comparatively weak. This is the realm of the classical theories of Marcus [1956], Hush [1958], Levich [1970], and German and Dogonadze [1974]. Outer sphere transfer can also involve the breaking of a bond (Fig. 2. lb), although the reactant is not in direct contact with the metal. In inner sphere processes (Fig. 2. Ic, d) the reactant is in contact with the electrode depending on the electronic structure of the system, the electronic interaction can be weak or strong. Naturally, catalysis involves a strong...

German ED, Dogonadze RR. 1974. The kinetics of nucleophilic substitution processes in the alkyl halides. Part A—theory. Int J Chem Kin 6 457-466, and references therein. 

Attempts were made to quantitatively treat the elementary process in electrode reactions since the 1920s by J. A. V. Butler (the transfer of a metal ion from the solution into a metal lattice) and by J. Horiuti and M. Polanyi (the reduction of the oxonium ion with formation of a hydrogen atom adsorbed on the electrode). In its initial form, the theory of the elementary process of electron transfer was presented by R. Gurney, J. B. E. Randles, and H. Gerischer. Fundamental work on electron transfer in polar media, namely, in a homogeneous redox reaction as well as in the elementary step in the electrode reaction was made by R. A. Marcus (Nobel Prize for Chemistry, 1992), R. R. Dogonadze, and V. G. Levich. 

Dogonadze, R. R., Theory of molecular electrode kinetics, in Reactions of Molecules at Electrodes, p. 135, see page 253. 

Dogonadze, R. R., L. I. Krishtalik, and V. G. Levich, Present state of the theory of the elementary step of electrode reactions (in Russian), Zh. Vsesoyuz. Khim. Obsh., 16, 613 (1971). 

Equation (77) shows that if ph lp(R )/4 1 at an optimum distance R between the reactants, proton transfer occurs by means of tunneling between the unexcited states. However, the distance of the proton jump, 2r0(R ), is not equal to the distance between the points of minima of the potential wells of the proton in the equilibrium nuclear configuration. This case is a generalization of the results obtained in an earlier model by Dogonadze, Kuznetsov, and Levich36 (DKL model). 

E D German and R R Dogonadze, Dokl Akad Nauk SSSR 210 (1973) 377... 

German ED, Kuznetsov AM, Dogonadze RR (1980) Theory of the kinetic isotope effect in proton transfer reactions in a polar medium. J Chem Soc, Faraday Trans 2 76 1128-1146... 

Table 6.6 lists some reactions of the electron in water, ammonia, and alcohols. These are not exhaustive, but have been chosen for the sake of analyzing reaction mechanisms. Only three alcohols—methanol, ethanol, and 2-propanol—are included where intercomparison can be effected. On the theoretical side, Marcus (1965a, b) applied his electron transfer concept (Marcus, 1964) to reactions of es. The Russian school simultaneously pursued the topic vigorously (Levich, 1966 Dogonadze et al, 1969 Dogonadze, 1971 Vorotyntsev et al, 1970 see also Schmidt, 1973). Kestner and Logan (1972) pointed out the similarity between the Marcus theory and the theories of the Russian school. The experimental features of eh reactions have been detailed by Hart and Anbar (1970), and a review of various es reactions has been presented by Matheson (1975). Bolton and Freeman (1976) have discussed solvent effects on es reaction rates in water and in alcohols. 

The Russian school of ETR (Levich, 1966 Dogonadze, 1971 Vorotyntsev et al, 1970) treats the medium polarization by a second-quantized Hamiltonian, written as... 

The theory of electron-transfer reactions presented in Chapter 6 was mainly based on classical statistical mechanics. While this treatment is reasonable for the reorganization of the outer sphere, the inner-sphere modes must strictly be treated by quantum mechanics. It is well known from infrared spectroscopy that molecular vibrational modes possess a discrete energy spectrum, and that at room temperature the spacing of these levels is usually larger than the thermal energy kT. Therefore we will reconsider electron-transfer reactions from a quantum-mechanical viewpoint that was first advanced by Levich and Dogonadze [1]. In this course we will rederive several of, the results of Chapter 6, show under which conditions they are valid, and obtain generalizations that account for the quantum nature of the inner-sphere modes. By necessity this chapter contains more mathematics than the others, but the calculations axe not particularly difficult. Readers who are not interested in the mathematical details can turn to the summary presented in Section 6. 

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