Urumqi Key Laboratory of Green Catalysis and Synthesis Technology, School of Chemistry and Chemical Engineering, Xinjiang University, Urumqi, 830046, China.
J Mol Model. 2013 Sep;19(9):3529-35. doi: 10.1007/s00894-013-1877-x. Epub 2013 May 29.
The relative aromaticity of pyrrole, furan, thiophene, and their aza-derivatives has been examined using TRE (topological resonance energy), MRE (magnetic resonance energy), ring current (RC), and ring current diamagnetic susceptibility (χG) methods. The results obtained were compared with results obtained by others who used the energetic method ASE (aromatic stabilization energy), the geometric method HOMA (harmonic oscillator model of aromaticity), and the magnetic method NICS(1) (nucleus-independent chemical shift). The impact of nitrogen atoms on the aromaticity of the aza-derivatives of pyrrole, furan, and thiophene is discussed. An excellent correlation was found between the energetic (TRE, MRE) and magnetic (RC and χG) criteria of aromaticity for all compounds. It was expected that inclusion of a heteroatom would decrease the aromaticity relative to the cyclopentadienyl anion. Our results show that the type of the first heteroatom, which donates two electrons to the system, as well as the number of nitrogen atoms and their positions in the molecule have a strong effect on aromaticity. In general, aromaticity is enhanced when the nitrogen atom is adjacent to the first heteroatom. The magnitude of aromaticity is related closely with the uniformity of distribution of π-electrons in the molecule.
已经使用 TRE（拓扑共振能）、MRE（磁共振能）、环电流（RC）和环电流抗磁磁化率（χG）方法研究了吡咯、呋喃、噻吩及其氮杂衍生物的相对芳香性。将得到的结果与其他人使用的能量方法 ASE（芳香稳定能）、几何方法 HOMA（芳香性的谐振子模型）和磁方法 NICS(1)（独立核化学位移）得到的结果进行了比较。讨论了氮原子对吡咯、呋喃和噻吩的氮杂衍生物芳香性的影响。对于所有化合物，都发现芳香性的能量（TRE、MRE）和磁（RC 和 χG）标准之间存在极好的相关性。预计包含杂原子会使相对于环戊二烯阴离子的芳香性降低。我们的结果表明，第一个杂原子的类型，它向系统提供两个电子，以及氮原子的数量及其在分子中的位置对芳香性有很强的影响。一般来说，当氮原子与第一个杂原子相邻时，芳香性会增强。芳香性的大小与分子中π 电子的分布均匀性密切相关。
