Thermal electron transfer in donor-acceptor complexes
An important distinctive feature of charge-transfer complexes (CTC) is their ability to generate radical ions as a result of thermal or photo excitation. The nature of electron phototransfer, it has been suggested, is determined by the properties of the excited electronic state of the complex. We have suggested that thermal reactions, including electron transfer, be considered as proceeding via excited states of CTC. Here we report a study of some general features of thermal electron transfer as exemplified by systems containing aromatic amines and anhydrides that act as models of the acylation reaction. Ionization of CTC forming radical cations and anions normally occurs only in polar media with strong donor-acceptor pairs. This is an activated process, i.e., it is accelerated by increase in solution temperature. We have examined several donor-acceptor systems (in dimethylformamide) in which the chemical structures of electron donor and acceptor were varied. At low temperatures, where thermal electron transfer is retarded, the electronic spectra of the complexes contain charge-transfer bands. With increase in temperature we detected the formation of a significant quantity of the amine radical. There are several important factors that markedly accelerate the charge-transfer process - the presence of oxygen, peroxides, or added proton-donating compounds.
- Research Organization:
- Inst. of High-Molecular-Weight Compounds, Leningrad, USSR
- OSTI ID:
- 5541791
- Journal Information:
- Dokl. Phys. Chem. (Engl. Transl.); (United States), Journal Name: Dokl. Phys. Chem. (Engl. Transl.); (United States) Vol. 244:1-3; ISSN DKPCA
- Country of Publication:
- United States
- Language:
- English
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