Synthesis of Symmetric Binuclear 5,6-Dihydro-1,2,4,5-tetrazinium Perchlorates

A series of 3,3′-(1,4-phenylene)bis(1-4-R-phenyl)-5-phenyl-5,6-dihydro-1,2,4,5-tetrazinium) perchlorates (R = H, Me, Cl, OMe, CN, NO 2 ) were obtained as a result of a three-stage synthesis from terephthalic aldehyde. The synthesis of tetrazinium salts was carried out by reaction of the corresponding formazans with formalin in the presence of perchloric acid in dioxane. Formazans and tetrazinium perchlorates were isolated in individual state and characterized by elemental analysis, IR, UV, 1 H, and 13 C NMR spectroscopy data. The process of electrochemical reduction of tetrazinium perchlorates was studied using the method of cyclic voltammetry (CV). It has been shown that these compounds are perspective precursors of symmetric biradical systems based on verdazyl radicals.