Mixed-valence complexes Hush model

Humulene complexes with silver, 12 343, 346 Hund s rule, 13 162 HupU protein, 47 289 HupUV proteins, 47 190 Hush model, 41 274-280 class II mixed-valence complexes, parameters, 41 293... 

The intellectual push to study mixed-valence complexes was provided by the publication in 1967 of two review articles, by Allen and Hush (2) and Robin and Day (3), on the physical properties of mixed-valence systems. These were followed by Hush s publication (4) of his theoretical model of intervalence transitions, which provided a link between the properties of mixed-valence complexes in solution and the Marcus theory of intermolecular electron transfer (5, 6). The review by Robin and Day classified mixed-valence complexes into three types class I,... 

From Eq. (19), Eop should be linearly proportional to the solvent term (1 IDop - 1 IDa). This relationship has been demonstrated for weakly coupled mixed valence complexes (see Section (II.C.2.c) and this gives qualitative support to the Hush model. 

In a recent study, Curtis and coworkers (34) developed an analysis of electronic coupling in mixed-valence complexes that combines electrochemical results with an extension of Mulliken s theory of donor-acceptor interactions. The approach was applied to class II and near class III complexes. It was found that the degree of electronic coupling in these systems is at least three times that which would be predicted based solely on spectroscopic measurements (Eq. 15 of the Hush model). However, the electronic coupling determined for complexes that were very close to, if not of, class III character was significantly smaller than that predicted by Eq. (16). 

Hush Model Calculated Parameters of Class II Mixed-Valence Complexes... 

An extended MuUiken-Hush treatment of mixed-valence complexes can be found in Chapter 2.45. In other studies, the effect of bridging ligand topology on metal-metal coupling was analyzed in terms of quantum interference. Ferretti et al have proposed a model for the study of the optical properties of mixed-valence complexes, and Coronado et have developed a general... 

Expressions (1) and (2) are the basis for the Hush-Marcus model. They allow the construction of potential energy curves of parabolic shapes, when the energy is plotted as a function of a composite reaction coordinate. These curves in turn are the basis for an elementary description of the thermal and optical processes in mixed valences complexes. In principle, it is possible to compute a rate constant from this model, using the total reorganization energy as an activation energy and introducing an electronic transmission factor calculated by the Landau-Zener formula. However this procedure is now supplanted by the quantum models. 

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