Protonated paramagnetic redox forms of di-o-quinone bridged with p-phenylene-extended TTF: A EPR spectroscopy study
Nikolay O Chalkov1, Vladimir K Cherkasov1, Gleb A Abakumov2
1Laboratory of Organoelement Compounds, G.A. Razuvaev Institute of Organometallic Chemistry of RAS, 603950, GSP-445, Tropinina str., 49, Nizhny Novgorod, Russia; N. I. Lobachevsky Nizhny Novgorod State University, Gagarina av., 23, Nizhny Novgorod, Russia.
Abstract:
The chemical oxidation and reduction processes of deprotonated, direduced o-quinone-exTTF-o-quinone in protic solvents were studied by EPR spectroscopy. The formation of relatively stable paramagnetic protonated redox forms of the parent triad was very surprising. The character of spin-density distribution in the semiquinone-quinone and semiquinone-catechol redox forms indicates that the p-phenylene-extended tetrathiafulvalene connector provides a quite effective electronic communication channel between dioxolene coordination sites. It was found that the deprotonated, direduced o-quinone-exTTF-o-quinone is capable to reduction of the metal copper in solution. The radical anion species formed in this reaction exists in solution as a solvent-separated ion pair with a copper cation. A character of spin-density distribution in a radical anion species leads to the conclusion that the ligand corresponds to type III of the Robin-Day classification.
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