The prototypal 1,5,2,4,6,8-dithiatetrazocine has been synthesized for the first time by two routes: reaction of 1,2,3,5-dithiadiazolium chloride with N,N,N′-tris(trimethylsilyl)formamidine in acetonitrile and reaction of 1,2,3,5-dithiadiazolyl radical with dioxygen in solution. Yields are low but single crystals could be obtained for an X-ray crystal structure determination which shows it to have the planar delocalized structure predicted by B3LYP/6-311+G(2d,p) hybrid DFT calculations. The crystal structure is strongly reminiscent of that of benzene in the same Pbca space group. Aromaticity is demonstrated by a 1H NMR chemical shift of +9.70 ppm indicative of diamagnetic ring shielding and an intense low-energy optical absorption with λmax = 349 nm (MeOH). The voltammetric behaviour of the title compound is compared with that of 1,3λ4δ2,5,2,4-trithiadiazepine; both resist electrochemical oxidation and reduction over a wide potential range as is typical for aromatic heterocycles.
1,5,2,4,6,8-二
硫杂四嗪的原型化合物首次通过两种途径合成:1,2,3,5-二
硫二唑
氯化物与N,N,N′-三(三甲基
硅烷基)
甲脒在
乙腈中的反应,以及1,2,3,5-二
硫二唑基自由基与溶液中的
氧气的反应。产率较低,但可获得单晶用于X射线晶体结构测定,测定结果表明其具有B3LYP/6-311+G(2d,p)混合DFT计算预测的平面非局域结构。该晶体结构与Pbca空间群中苯的晶体结构非常相似。1H NMR
化学位移为+9.70 ppm,表明存在抗磁性环屏蔽效应,且存在强烈的低能光学吸收,λmax = 349 nm (MeOH)。将标题化合物的伏安行为与1,3λ4δ2,5,2,4-三
硫二氮杂卓的伏安行为进行比较,两者在宽电位范围内均能抵抗电
化学氧化和还原,这是芳香杂环的典型特征。