The mechanism for the catalysis of electron-transfer reactions in systems with weak donor-acceptor properties has been considered. According to this mechanism, the reaction proceeds via the low-lying excited states of the complexes. These states are generated as a result of multiorbital bonds between the molecules of the reagents. The significant p?rt played by hydrogen and other bridge bonds in the stabilization of the excited levels of the complexes is shown. The energetic characteristics of complexation (charge-transfer energy) and hydrogen-atom transfer (activation energy and reaction heat) are compared, taking as an example solid-phase hydrogen-bonded 7r complexes.One of the principal problems of the theory of chemical reactions in polymeric systems is elucidation of the nature of the potential barrier determining the reaction rate and the structure of the product. It is helpful to study the activated (transition) state of the reaction as one of the electronic states of the reacting system, which makes it possible to treat from a general standpoint the analysis of both catalytic and non-catalytic reactions. In ref.(1)-( 4) it has been stated that thermal reaction proceeds via the low-lying electronically excited state of a molecular complex of the reagents. In the framework of these concepts the similar character of photoand thermo-chemical reactions is established and electron excitation (transfer) is considered to be an elementary stage. The important role played by electron transfer in chemical reactions has been confirmed by experimentalThe present work deals with catalysis of the electron-transfer reaction in systems with weak donor-acceptor properties. This catalysis, in the general sense, is understood as the formation, by the multiorbital bonds between the molecules of the reaction system, of low-lying excited states. Thus the elucidation of the physical mechanisms for the stabilization of intermolecular electronic levels and their physical confirmation are important problems. Redox reactions of solid-phase hydrogenbonded 'TT complexes are considered to be suitable for catalytic electron transfer and are used for a comparison of the energetic characteristcs of the reaction and complexat ion.
EXPERIMENTALThe spectral procedure for the investigation of solid complexes has been described previ~usly.~ The reflection spectra of complexes in the visible range were studied using an ATR attachment (fianite, 45") and the absorption spectra were studied in Vaseline oil. Low-temperature electron spectra were obtained using a vacuum quartz cell. For the kinetic measurements samples of the solid complexes were pressed in KBr discs. The kinetic curves were plotted according to the change in the intensity of the i.r. absorption bands corresponding to reagents or products. The e.p.r. spectra of the complexes were obtained using a Bruker
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