Stabilization of Triplet Polynuclear Aromatic carbene

三线态多核芳香卡宾的稳定化

• 批准号: 14540493
• 负责人: HIRAI Katsuyuki
• 金额: $ 2.24万
• 依托单位: Mie University
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (C)
• 财政年份: 2002
• 资助国家: 日本
• 起止时间: 2002 至 2003
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-14540493/
• 关键词: diazo compound; triplet carbine; laser photolysis; steric protection; anthryl group; electron spin resonance

Triplet di(9-anthryl)carbene has almost completely linear and perpendicular structure, suggesting that unpaired electrons are extensively delocalized and hence the carbene center is protected by four perihydrogens. Thus, the carbene was expected to be persistent. Contrary to this expectation, its lifetime in a degassed benzene at room temperature is only 0.5μs, which is as short as that of triplet diphenylcarbene.This is because it decays by coupling reactions at 10,10'-positions where spin is delocalized. In order to inhibit the coupling reactions, we have generated dianthrylcarbene having two phenyl groups at 10,10'-positions and indicated that it was a dramatically long-lived triplet carbene (t1/2 = 40 min). We found triplet dianthrylcarbene(2a) having 2,6-dimethyl-4-tert-butylphenyl groups at 10,10'-positions was much more persistent with half-life of 50 hours. Since the carbene(2a) decayed by second-order kinetics, it appeared to decay by dimerization at the carbene carbon. In order to inhibit the dimerization, triplet dianthrylcarbene(2b) bearing four bromo groups at 2,7-positions on anthracene rings was generated by photolysis of the corresponding diazo compound and the half-life(t1/2 =6.5 min) of 2b was determined to be shorter than that of dianthrylcarbene(2a).

三重态二（9-蒽基）卡宾具有几乎完全线性和垂直的结构，表明未成对电子广泛离域，因此卡宾中心被四个过氢保护。因此，预期卡宾具有持久性。与预期相反，它在室温下脱气苯中的寿命只有0.5μs，与三重态二苯基卡宾的寿命一样短，这是因为它在10，10 '-位上通过耦合反应衰变，此时自旋离域。为了抑制偶联反应，我们已经生成了在10，10 ′-位上具有两个苯基的二蒽基卡宾，并表明它是一个非常长寿命的三重态卡宾（t1/2 = 40 min）。我们发现在10，10 ′-位具有2，6-二甲基-4-叔丁基苯基的三重态二蒽基卡宾（2a）具有更持久的半衰期，为50小时。由于卡宾（2a）通过二级动力学衰变，因此它似乎通过在卡宾碳处的二聚化衰变。为了抑制二聚反应，通过光解相应的重氮化合物，在蒽环2，7-位上产生了四个溴原子的三重态二蒽基卡宾（2b），其半衰期（t1/2 = 6.5min）比二蒽基卡宾（2a）短。

项目成果

Eri Iwamoto: "A Triplet Carbene Surviving a Week in Solution at Room Temperature"J.Am.Chem.Soc.. 125. 14664-14665 (2003)

Eri Iwamoto：“三重态卡宾在室温溶液中存活一周”J.Am.Chem.Soc.. 125. 14664-14665 (2003)

Eri Iwamoto: "A Triplet Carbene Surviving a Week in Solution at Room Temperature"J.Am.Chem.Soc. 125・48. 14664-14665 (2003)

Eri Iwamoto：“三重态卡宾在室温下在溶液中存活一周”J.Am.Chem.Soc. 125・48 (2003)。

Eri Iwamoto: "A Triplet Carbene Surviving a Week in Solution at Room Temperature"Journal of the American Chemical Society. 125・48. 14664-14665 (2003)

Eri Iwamoto：“三线态卡宾在室温下在溶液中存活一周”美国化学会杂志 125・48（2003 年）。