Triplet complex

A typical special feature of the melts of ionic crystals (ionic liquids) are their high concentrations of free ions, of about 25 M. Because of the short interionic distances, considerable electrostatic forces act between the ions, so that melts exhibit pronounced tendencies for the formation of different ionic aggregates ion pairs, triplets, complex ions, and so on. 

A thermal oxidation of 2,3-dimethyl-2-butene, 16, occurs in NaY when the temperature of the oxygen-loaded zeolite in raised above — 20°C [35], Similar thermally initiated oxidations were not observed for the less electron rich tram-or cix-2-butene. Remarkably, pinacolone was conclusively identified as one of the products of the reaction of 16, This ketone is not a product of the photochemical Frei oxidation (vide supra) and underscores the very different character of these two reactions and the complexity of the oxygen/16 potential energy surface, A rationale for the different behavior could lie in the different electronic states of the reactive oxygen-CT complex in the thermal and photochemical reactions. Irradiation could produce an excited triplet-state CT complex ( [16 O2] ) and/ or ion pair ( [16 02 ] ) with different accessible reaction channels than those available to a vibrationally excited ground-state triplet complex ( [16 "02]) and/... 

If they are different. These complexes only exist in the excited state and they dissociate into monomers upon deactivation. While the existence of singlet excimers and exciplexes has been proved by many investigators, only a few reports deal with triplet complexes. 

Spin Selectivity. As a consequence of the preceding, reaction rates depend on the electron spin multiplicity. In many cases, the difference is so large that it practically amounts to a yes-no decision. As a typical example, consider an encounter complex, at the reaction distance, of two radicals, which can have either triplet or singlet multiplicity. In most cases, reaction will be impossible for the triplet complex because it would lead to an electronically excited product. For reaction of the singlet complex, there is no such restriction. 

Ketone Triplet Complex -CD x(ns) Triplet Radical Pair ... 

Small periodic AUst values were obtained for Ca203 (Table 20.6). A decrease of the energy differences AUst between the singlet and triplet complexes containing O2 species was already discussed in the literature [55, 65]. A precise value of small... 

Figure 3.13 Gibbs free energy profile at 298.15 K for the spin crossover at lEa. The quintet parts are shown in black, while the triplet complexes are in gray. The MECPs are marked with solid cycle. Energies are in kcal/mol and relative to 1C plus the corresponding number of methylacetylenes.

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