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首页> 外文期刊>Chemistry: A European journal >Can Substituted Cyclopentadiene Become Aromatic or Antiaromatic?
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Can Substituted Cyclopentadiene Become Aromatic or Antiaromatic?

机译：取代的环戊二烯能否变成芳香族或抗芳香族？

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摘要

Cyclopentadiene derivatives with electronegative(F,Cl)or electropositive(H_3Si,Me_3Si)bis-5,5-substit-uents were studied at the B3LYP/6-311G* level of theory.It was found that there is no special stabilization or destabilization for any of the derivatives;the energetic effects that were previously attributed to aromatic stabilization or antiaromatic destabilization are the result of interactions in the reference systems.A nucleus-independent chemical shift(NICS)scan study at the HF-GIAO/6-311+G* theoretical level of these and similar derivatives suggest that they all show different magnitudes of diamagnetic ring current.None of the derivatives shows a paramagnetic ring current.Thus,cyclopentadienes are neither aromatic nor antiaromatic.It is also concluded that a diamagnetic ring current is perhaps necessary but certainly not a sufficient condition for aromaticity.The NICS scan procedure describes the type of ring current in the system,whereas a single isotropic NICS value(i.e.,NICS(1))may wrongly assign the type of ring current.It is shown that neither NICS(1)nor the NICS scan procedure can be used as a single aromaticity criterion.
机译：在理论水平为B3LYP / 6-311G *的条件下研究了具有负电（F，Cl）或正电（H_3Si，Me_3Si）bis-5,5-取代基的环戊二烯衍生物，发现没有特殊的稳定或去稳定作用。对于任何衍生物;以前归因于芳族稳定或抗芳族去稳定的能量效应是参考系统相互作用的结果.HF-GIAO / 6-311 +上的核独立化学位移（NICS）扫描研究这些衍生物和类似衍生物的G *理论值表明它们都显示出不同的抗磁环电流。这些衍生物都没有显示顺磁环电流。因此，环戊二烯既不是芳族化合物也不是抗芳族化合物。 NICS扫描过程描述了系统中环电流的类型，而单个各向同性NICS值（即，NICS（1） ）可能会错误地分配振铃电流的类型。表明NICS（1）或NICS扫描程序均不能用作单个芳香性标准。

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