Chemical reduction of 2,4,6-tricyano-1,3,5-triazine and 1,3,5-tricyanobenzene.: Formation of novel 4,4′,6,6′-tetracyano-2,2′-bitriazine and its radical anion

Chemical reduction of 2,4,6-tricyano-1,3,5-triazine, TCT, results in the formation of an unstable radical anion that undergoes immediate dimerization at a ring carbon to form [Cl2N12](2-), [TCT](2)(2-), characterized by a long 1.570 (4) Angstrom central C-C bond. [TCT](2)(2-) can decompose into the radical anion of 4,4',6;6'-tetracyano-2,2'-bitriazine, [TCBT](.-), the one-electron reduced form of planar (D-2h) TCBT, which is also structurally characterized as the [TMPD] [TCBT] charge-transfer complex (TMPD = N,NN',N'-tetramethyl-p-phenylenediamine) with a 1.492 (2) Angstrom central sp(2)-sp(2) C-C bond. Although crystals could not be obtained for the radical anion [TCBT](.-), the electrochemistry (Edegrees = +0.03 V), EPR (g = 2.003, (2)A(14N) = 3.347 G, and (4)A(14N) = 0.765 G and a line width of 0.24 G), and theoretical calculations support the formation of [TCBT](.-). In addition, thermolysis of [TCT](2)(2-) yields [TCBT](.-). Chemical reduction of 2,4,6-tricyanobenzene, TCB, forms an unstable radical anion that immediately undergoes dimerization at a ring carbon to form [C12H6N6](2-), [TCB](2)(2-), which has a long 1.560 (5) Angstrom central C-C bond. Reaction of TCT with tetrathiafulvalene (TTF) forms structurally characterized [TTF] [TCT], and in the presence of water, TCT hydrolyzes to 2,4-dicyano-6-hydroxy-s-triazine, DCTOH. In contrast, the reaction of TCT with TMPD forms [TMPD][TCT], which in the presence of water forms structurally characterized [HTMPD](+)[DCTO](-).