宝塔烷电子结构与张力的ab initio研究

利用MNDO程序优化出宝塔烷、宝塔烷双正离子及宝塔二烯的构型参数。从头算的电荷分布及分子轨道均表明: 宝塔烷与其价键异构体宝塔二烯性质相近。双正离子的中间四个碳原子则形成了一种与环丁烷双正离子类似的四中心双电子大π键。张力研究表明, 宝塔烷的键张力要比不能稳定存在的小螺桨烷小得多, 说明了宝塔烷骨架的刚性及稳定性。

Ab initio studies on the electronic structure and strains of pagodanes

The geometries of pagodanes were optimized by the MNDO procedure. The anal. of atomic charges and MO compns. obtained from ab initio calcns. shows that the properties of pagodane are similar to those of its diene valence isomer and that the 4 central C atoms in pagodanes may be more active in chem. reactions. A 4-center/2-electron delocalized system is formed in the plane of the 4 central carbons in pagodane dication, which resembles the cyclobutane dication. Bond strain in pagodanes is much less than in small propellanes, which are not stable. This can explain the rigidity and stability of pagodane framework.