Tuning properties of 3,6-disubstituted-s-tetrazine by changing the chemical nature of substituents

Six 3,6-disubstituted-s-tetrazine, symmetrical and unsymmetrical, derivatives have been characterized electrochemically and spectroelectrochemically. Our studies started from 3,6-dichloro-s-tetrazine and afterwards the effect of halogen replacement with the ethoxy and phenoxy group was examined. Then, the influence of heterocyclic substituents was investigated. Finally, the reduction process of compound with two s-tetrazine ring in its structure was analyzed. The systematic EPR investigations of electronic structure of studied anion-radicals are presented. Those studies have revealed an unusual behavior of a compound featuring two connected s-tetrazine rings in its structure. Reduction of this compound proceeds as a two-step process which leads to formation of two radicals with different g-factors: one of them localizes on one s-terazine ring as a result of the first step and the second radical localizes on another ring in the second step of reduction.