Electron-preceding perspectives

The geometrical relaxations, in response to displacements in the electronic structure of the acid-base (acceptor-donor) reactive system, are also the subject of the intuitive, structural bond-variation rules of Gutmann [62]. They also follow the above Hellmann-Feynman (electron-preceding) perspective of Nakatsuji, who obtained interesting interrelations between changes in the electron density and nuclear configuration in a variety of contexts associated with chemical reactions. He has shown, for example, that the centroid of a... 

The study of organic electron-transfer processes may superficially seem to be a rather futile academic exercise two species collide, an electron is transferred between them, and two new species are formed. Naturally, the story does not begin or end here. It is the preceding and subsequent steps that put electron transfer in its correct perspective and determine its usefulness in chemistry, in science as a whole and in society. The following applications of electron transfer processes speak for themselves ... 

Several methods are available to analyze the electronic structure and discuss the chemical bonding of molecules and solids in a quantitative as well as qualitative way. Various levels of sophistication exist. From the chemist s perspective, electron counting schemes, such as the Zintl-Klemm (Klemm 1958 Schafer and Eisenmann 1981, von Schnering 1985), Mooser-Pearson (Mooser and Pearson 1956, 1960), or the (8 — N) rule (Kjekshus and Rakke 1974), which were frequently applied in the preceding section, are useful tools to understand relationships between composition and structure, structure and bonding, bonding and properties. Molecular orbital... 

This section will selectively summarize concepts and principles governing electron transfer. The selectivity is an obvious necessity in view of the vast amount of material, some of it cited in the preceding section, and the author s experience and bias. The perspective of this chapter is phenomenological. Theoretical studies and concepts will be used as a framework for the consideration of experimental studies. The emphasis is on those theoretical issues and concepts that relate to experimental studies of coordination complexes. A good overview of the theory can be found in a recent chapter by Newton. 

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