Does π−σ−π Through-Bond Coupling Significantly Increase C−C Bond Lengths?
Does π−σ−π Through-Bond Coupling Significantly Increase C−C Bond Lengths?
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π−σ−π 通过键耦合是否会显着增加 C−C 键长？
DOI：
10.1021/ja9622315
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发表时间：
1997
影响因子：
15
通讯作者：
A. Siegel
中科院分区：
文献类型：
--
作者：
A. Battersby;aand Russell VernonClark;A. Siegel
归因于π−σ−π通键耦合的轨道效应主要是不稳定填充的−填充相互作用的结果；反对称π组合与σ*之间很少或没有混合。贯通键耦合的大小与键的延长无关。以往关于直通键耦合导致长键的结论在某些情况下依赖于较差的X射线数据和/或不适当的分子轨道理论来推导几何构型。比较半经验和经验力场数据作为贯通键耦合的测试是不必要的。标准力场低估了苯面的立体体积，但添加所谓的“贯键耦合”项并不能提供通键耦合的物理意义上的量度。
Orbital effects ascribed to π−σ−π through-bond coupling are the result primarily of destabilizing filled−filled interactions; little to no mixing occurs between the antisymmetric π combination and σ*. The magnitude of through-bond coupling does not correlate with bond lengthening. Previous conclusions that through-bond coupling induces long bonds relied in some cases on poor X-ray data and/or inappropriate molecular orbital theories to deduce geometries. Comparison of semiempirical and empirical force field data as a test for through-bond coupling is unwarranted. Standard force fields underestimate the steric bulk of the benzene face, but addition of so-called “through-bond coupling” terms does not provide a physically significant measure of through-bond coupling.