三线态二苯基卡宾的动力学稳定效应  

Kinetic Effect on Stability of the Triplet Diphenylcarbene

作　　者：胡应模[1] 平井克幸 富冈秀雄 

机构地区：[1]日本国津市三重大学工学部

出　　处：《Chinese Journal of Chemical Physics》2001年第4期397-402,共6页化学物理学报（英文）

摘　　要：通过对二苯基重氮甲烷进行光照射产生了一系列于邻位和对位具有不同大小取代基的三线态二苯基卡宾。用紫外可见光谱对其进行了直接观察 ,并利用激光闪光光解法测定了三线态二苯基卡宾在室温脱氧苯溶液中的寿命 。Carbene is a very important reactive intermediate to explain organic reaction mechanism that cannot be considered by generally; on the other hand, the triplet carbene has been considered to the unite of organic magnetic materials owing to its special electronic structure that has a parallel electronic configuration described as σ 1ρ 1. However the triplet carbene is too reactive to trap, for instance, the lifetime of triplet diphenylcarbene is only 0.002ms. For this reason the stabilization of carbene would be necessary for organ chemistry and advance organic materials. Two basic strategies, i.e., thermodynamic and kinetic stabilization, are possible for the stabilization of reactive species. Studies examining the relationship between structure and reactivity have shown that thermodynamic stabilization (electronic conjugation effect) usually play an important role in stabilizing the singlet state and that the singlet state undergoing the stabilization becomes less reactive due to the contribution of the conjugation to such an extent that the species can be isolated under ambient condition. On the other hand, kinetic stabilization (steric protection) is more effective in stabilizing the triplet counterpart since the introduction of sterically bulky groups around the carbenic center results in an increase in the carbene bond angle and protection the carbenic center attacked by minor impurities in the surrounding medium, i.e., a trace of oxygen. To explorer the stable effect of substituents on the triplet diphenylcarbene, in the preceding paper, we had generated a series of triplet diphenylcarbenes, in which have various substituents at the para- or ortho-position by photolysis of the corresponding diphenyldiazomethane at room temperature, and studied their reactivities with oxygen by laser flash technique. And revealed that the substituents whether para- or ortho-position can cause the stable effect on the triplet diphenylcarbenes, and the steric protective effect in ortho-position is more effective. In order t

关 键 词：三线态二苯基卡宾 紫外可见光谱 取代基效应 激光闪光光解法 游离基化学 动力学稳定效应 

分 类 号：O644[理学—物理化学]