Marcus formalism

The origin of Groups I and II is otherwise rationalized in terms of the Marcus formalism (54) as in the case of HRP-catalyzed oxidation of phenols (125,126). The data in Fig. 11 are plotted to highlight the inverted Marcus region in reaction (37). The following standard assumptions have been made in the calculations (53,54) ... 

Marcus formalism has been applied to understanding the strategies by which active sites stabilize the transition states for proton transfer to and from carbon [12, 13]. This is based on the usual assumption that the equation for an inverted parabola can be used to describe the dependence of the free energy, G, on the reaction coordinate, X, where x = 0 for carbon acid substrate/general base and x = 1 for the enolate anion intermediate/conjugate acid of the general base. 

According to Marcus formalism, the value of the activation energy barrier, AG, is specified by the following equation ... 

It needs to be emphasized that the intrinsic rate constants obtained via equations (99) and (100) are subject to significant uncertainty, especially those for which log A or log AT differ substantially from zero. This is because equations (99) and (100) are based on the simplest form of the Marcus" formalism (first two terms in equation 101) which may be a good approximation when AG° is close to zero but less so when IAG°I becomes large (third term in equation 101). The log k, values for these latter cases are identified by italics in the table. 

One aspect of the problems encountered in the description of outer-sphere electron transfer reactions within the Marcus formalism is that the self-exchange rate of Eu(III)/Eu(II) has not been measured. Therefore, estimates have been calculated for this rate from measurements of the rates of reactions of systems that are well characterized, i.e. the equihbrium constant is known. In addition, there is substantiating evidence that the reaction is outer-sphere, and the value for self-exchange... 

C. How Well Does the Butler-Volmer Expression Approximate the Marcus Formalism 118... 

An important contribution from the field of intramolecular organic electron-transfer is the discovery of some reactions that clearly show the inverted region indicated by the Marcus formalism [23]. As we noted earlier (Section 9.1.2.6), the Marcus model predicts that, in... 

In this section we summarize developments in kinetics which are closely related to the standard Marcus formalism. That is, for a general electron transfer reaction (1),... 

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