5，6，9，10—四脱氢苯并环辛烯结构和性质的理论研究

Theoretical Studies on the Structures and Properties of 5,6,9,10 - Tetradehydrobenzocyclooctene

在RHF/6-31G**,MP2/6-31G**,B3LYP/6-31G**水平下优化了5,6,9,10-四脱氢苯并环辛烯的平衡几何构型.用的LYP/6-31G**方法计算了该化合物的红外光谱、拉曼光谱、核磁共振谱.计算结果与实验结果吻合很好,从而在理论上证实了它的存在.用等键反应分析,自然键轨道方法对它的稳定性和共轭性分别进行了讨论.结果表明5,6,9,10-四脱氢苯并环辛烯分子为平面刚性结构,可能稳定存在.但由于苯环共轭性的削弱和较高的张力,使得它易于分解.

The structures of 5,6,9,10 - tetradehydrobenzocyclooctene have been optimized at the RHF/6 - 31G**, MP2/6 - 31G**, B3LYP/6-31G** levels. At the B3LYP/6 - 31G** level, the IR spectrum, the Raman spectrum and the NMR spectrum have been calculated. The calculated results are well consistent with the experimental data, theoretically proving the existence of 5,6, 9, 10 - tetradehydrobenzocyclooctene. The isodesmic reaction and natural bond orbital analysis for 5,6, 9, 10 - tetradehydrobenzocyclooctene have been obtained at the B3LYP/6 - 31G** level. The results show that 5,6,9,10 - tetradehydrobenzocyclooctene has a relatively rigid planar structure. Because of the weakened conjugated actions between the carbon - carbon double bonds in the benzene ring and its strong strain in molecule, 5,6,9, 10 - tetradehydrobenzocyclooctene decomposes easily.