Itoh Tetsuji, Hirai Katsuyuki, Tomioka Hideo
Chemistry Department for Materials, Faculty of Engineering, Life Science Research Center, Mie University, Tsu, Mie 514-8507 Japan.
J Am Chem Soc. 2004 Feb 4;126(4):1130-40. doi: 10.1021/ja038450p.
9-[10-(4-tert-Butyl-2,6-dimethyl)phenyl]anthryldiazomethane was found to be stable enough to survive under Suzuki coupling conditions and underwent mono-, di-, and trisubstitution with benzene mono-, di-, and triboronic acids to afford benzene derivatives having one, two, and three diazo units, respectively. The products from irradiation of those diazo compounds were characterized by ESR and SQUID measurements, which revealed that triplet, quintet, and septet ground states were formed from mono-, bis-, and tris(diazo) compounds, respectively. The stability of those high-spin species was estimated by temperature-dependent ESR and UV/vis measurements as well as laser flash photolysis, which indicated that all three species are stable up to 160 K and have a half-life of a few seconds in solution at room temperature. The finding unequivocally shows that a precursor diazo unit can basically be handled as a building block to construct ploydiazo compounds and that persistent triplet carbenes, even though they greatly lose typical reactivity as a triplet carbene, still retain electronic properties and act as a spin source when aligned properly in the pi-electron frameworks to generate a high-spin molecule with remarkable thermal stability.
9-[10-(4-叔丁基-2,6-二甲基)苯基]蒽基重氮甲烷被发现具有足够的稳定性，能够在铃木偶联条件下存活，并分别与苯单硼酸、二硼酸和三硼酸发生单取代、二取代和三取代反应，得到分别具有一个、两个和三个重氮单元的苯衍生物。通过电子自旋共振（ESR）和超导量子干涉仪（SQUID）测量对这些重氮化合物辐照后的产物进行了表征，结果表明单重氮、双（重氮）和三重氮化合物分别形成了三重态、五重态和七重态基态。通过温度依赖的ESR和紫外/可见光谱测量以及激光闪光光解对这些高自旋物种的稳定性进行了评估，结果表明所有这三种物种在高达160 K时都是稳定的，并且在室温下的溶液中半衰期为几秒。这一发现明确表明，前体重氮单元基本上可以作为构建多重重氮化合物的构建块来处理，并且持久三重态卡宾尽管大大丧失了作为三重态卡宾的典型反应性，但在π电子框架中正确排列以生成具有显著热稳定性的高自旋分子时，仍保留电子性质并充当自旋源。
