the electron-withdrawing character of the para substituent increases. In addition, the rate ascribed to the interconversion of neutral cis rotamers through hindered rotation around the nitrogen-nitrogen single bond is found to decrease as the electron-withdrawing character of the para substituent increases. Rates of interconversion of neutral cis rotamers are also found to decrease with decreasing solvent
通过激光闪光光解技术研究了一些对称的p,p'-二取代的1,3-二苯基
三氮烯的顺式-反式异构化。由于酸/碱促进的1,3-质子重排,一般的酸和一般的碱可催化几何异构化。随着对位取代基的给电子性的增加,酸催化变得更加突出,而随着对位取代基的吸电子性的增强,碱催化变得更加重要。另外,发现由于对位取代基的吸电子特性的增加,归因于中性顺式旋转异构体通过围绕氮-氮单键的阻碍旋转而相互转化的速率降低。还发现中性顺式旋转异构体的相互转化率随着溶剂极性的降低而降低,这表明涉及极性过渡态。另一方面,目标
三氮烯的酸催化分解的动力学研究与A1机理是一致的。