Preparation of bis(diazo) compounds incorporated into butadiyne and thiophene units and generation and characterization of their photoproducts
作者:Fumika Morisaki、Masakuni Kurono、Katsuyuki Hirai、Hideo Tomioka
DOI:10.1039/b409095k
日期:——
remarkable increase in the lifetime of bis(carbenes), as opposed to that of the monocarbene (2), was noted and was interpreted to indicate that bis(carbenes) are thermodynamically stabilized as a result of delocalization of unpaired electrons throughout the pi net framework. In spite of the stability, both bis(carbenes) are readily trapped by molecular oxygen to afford bis(ketones). Presumably, the reaction
发现(2,6-二甲基-4-叔丁基苯基)(2,4,6-三溴苯基)重氮甲烷(-N(2))足够稳定,可以在Sonogashira偶联反应条件下生存,并在10,000℃处引入了芳基重氮甲基取代基丁二炔(4-2N(2))的1,4-位和噻吩(5-2N(2))的2,5-位。辐照这些双(重氮)化合物可生成双(卡宾),其特征是在低温下在基质中使用ESR和UV / vis光谱技术以及在室温下在溶液中使用时间分辨UV / vis光谱。这些研究表明,双(碳烯)4和5均具有单重态醌双自由基基态,其单重态-三重态的能隙非常小,小于1 kcal mol(-1)。与单碳烯(2)相比,双(碳烯)的寿命显着增加,注意到并解释为指出,由于整个π构架中未配对电子的离域作用,双(卡宾)在热力学上稳定了。尽管具有稳定性,两种双(卡宾)仍容易被分子氧捕获而得到双(酮)。据推测,位于较高处的局部五重态与氧气的反应要比位于较低处的五重态的反应快得多。