A Theoretical Study of Compounds Containing Heavier Main Group 14 and 15 Atoms

我们对骨架由较重的14族（Si、Ge、Sn和Pb）和14族（P、As、Sb和Bi）原子组成的化合物进行了从头计算，以期获得碳化合物所不具备的新性质。一个主要的问题是比较重原子骨架与碳骨架的特征，并预测在新材料设计中有用的一般规律。双键化合物。由于14族原子形成杂化轨道的倾向较低，它们变重后就不能形成双键。相反，较重的第15族原子在形成双键时并非特别不利。芳香族和反芳香族化合物。在碳化学中建立的芳香性和反芳香性等概念在应用于苯和环丁二烯的较重类似物时价值有限。取代基在设计芳香族或反芳香族化合物中起着重要的作用。多环化合物。当骨架碳被较重的原子取代时，多环碳化合物的应变能大大降低。这一性质对于设计应变较小的多环笼状化合物是有用的。异常短的幻影债券。提出了几个在碳化学中未见的重原子间键合的有趣性质。

We have carried out ab initio calculations of the compounds whose skeletons are made of the heavier main group 14 (Si, Ge, Sn, and Pb) and group 14 (P, As, Sb, and Bi) atoms in the expectation of novel properties which carbon compounds do not have. A primary concern is to characterize the heavier atom skeletons compared with carbon skeletons and predict a general rule which is useful in the design of new material.Doubly Bonded Compounds. The atoms in group 14 are incapable of forming double bonds as they become heavier because of a lower tendency to form hybrid orbitals. In contrast, the tendency of the heavier group 15 atoms is not especially unfavorable in forming double bonds.Aromatic and Antiaromatic Compounds. Concepts such as aromaticity and antiaromaticity established in carbon chemistry are of limited value when they are applied to the heavier analogues of benzene and cyclobutadiene. Substituents play a important role in designing aromatic or antiaromatic compounds.Polycyclic Compounds. The strain energies of polycyclic carbon compounds are greatly decreased when the skeletal carbons are replaced by the heavier atoms. This property is noteworthy since it is useful for designing less strained polycyclic cage compounds.Unusually Short Phantom Bonds. Several interesting properties of bonding between the heavier atoms are suggested which is not seen in carbon chemistry.