Stabilization of electrons

Olofsson-Martensson, M., U. Haussermann, J. Tomkinson, and D. Noreus, Stabilization of electron-dense palladium-hydrido complexes in solid-state hydrides, /. Am. Chem. Soc., 122, 6960,2000. 

In summary, the space strain is indicative of the stability of electron-transfer products. Electrode reactions fail to reveal such an effect. In liquid-phase processes, this effect, however, plays a decisive role. As Baizer and Lund s book (1983, p. 907) underlines... 

Because ionic liquids are in general weakly coordinating, they display low nu-cleophilicity. Such an environment favors the stabilization of electron-deficient intermediates (7). This unique property allows ionic liquids to be used as nonsolvating media for the stabilization of strongly acidic species. It is this property that has given rise to the superacidity of non-solvated protons in acidic [AMIM]Al2Clv 103). 

Thus, nanosecond techniques are usually limited to a few nanoseconds on the short end, presently related to the pulse duration (2-20 ns) of typical nanosecond lasers. Long times are frequently limited by either the stability of electronic-optical components, or by the fact that in the absence of other processes many reaction intermediates (e.g., free radicals and carbenes) can undergo rapid self-reactions. Nanosecond techniques rarely extend beyond a few tens of milliseconds. 

A number of papers have appeared recently in which semiempirical quantum mechanical methods, such as the complete neglect of differential overlap (CNDO), incomplete neglect of differential overlap (INDO), or Hiickel methods, have been applied to electron-deficient systems in an attempt to calculate their properties (31, 49, 64, 75, 77, 78, 89, 90, 92). Although the quantitative results of these calculations must be treated with great care, they do provide an indication of some of the parameters that determine formation and stability of electron-deficient bonded systems. 

Solvent Effects on the Stabilization of Electronic Isomers of Mixed-Valence Ions... 

The electron patterns are the primal shapes of nature. Fundamentally, all of nature s shapes can be traced to such patterns. Even the properties of living substances are based on them—in particular, the properties of the molecules that carry the hereditary code. In the final scientific analysis, the stability of electron wave patterns causes the same flowers to bloom every spring and makes children similar to their parents. 

In the case of adiabatic electron transfer reactions, it is found that the potential energy profiles of the reactant and product sub-systems merge smoothly in the vicinity of the activated complex, due to the resonance stabilization of electrons in the activated complex. Resonance stabilization occurs because the electrons have sufficient time to explore all the available superposed states. The net result is the attainment of a steady, high, probability of electron transfer. By contrast, in the case of -> nonadiabatic (diabatic) electron transfer reactions, resonance stabilization of the activated complex does not occur to any great extent. The result is a transient, low, probability of electron transfer. Compared with the adiabatic case, the visualization of nonadiabatic electron transfer in terms of potential energy profiles is more complex, and may be achieved in several different ways. However, in the most widely used conceptualization, potential energy profiles of the reactant and product states... 

Thermal Stability of Electron-Irradiated Poly(tetrafluoroethylene)... 

Cationic sandwich complexes of the type CpCo(arene) + were first prepared by hydride abstraction from cyclohexadi-enyl cations (Section 7.1). They are accessible in broader variation from the reaction of CpCoX half-sandwich complexes with arene in the presence of AICI3. Their electrochemical reductions to the corresponding 19-electron monocations and to 20-electron neutral complexes have been studied. The stability of electron-rich sandwich complexes increases with increasing alkyl substitution in either ring despite the more negative redox potential mass spectrometry studies of bond dissociation energies of (arene)Co+ complexes corroborate these results. However, neutral sandwich complexes are not very stable in the polar solvents necessary for the reduction of mono- or dications and have been isolated only from alkyne trimerization with CpCo precursors in nonpolar solvents (Section 5.1.4). 

We observe that the equilibrium in Eq. (113) is most stable (i.e., the change in / and nv needed to reestablish equilibrium is minimal) when r i and qv are large. Similarly, large values of the chemical hardness are associated with the stability of electronic systems [80]. 

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