5,6,9,10-四脱氢苯并环辛烯结构和性质的理论研究

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B3LYP/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。

Theoretical studies on the structures and properties of 5,6,9,10- tetradehydrobenzocyclooctene

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 Rama 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^** leve. 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.