Is C50 a superaromat? Evidence from electronic structure and ring current calculations.
Is C50 a superaromat? Evidence from electronic structure and ring current calculations.
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DOI：
10.1039/c5cp04970a
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发表时间：
2016-04
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影响因子：
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通讯作者：
A. Matías;R. Havenith;M. Alcamí;A. Ceulemans
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文献类型：
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作者：
A. Matías;R. Havenith;M. Alcamí;A. Ceulemans
根据 2(N + 1)(2) 规则，富勒烯-50 是一个“幻数”笼。对于具有三角和五角对称性的 C50 的三种最低异构体，我们计算了球形指数、占据的 π 轨道的球形母体以及外加磁场中的电流密度。具有 D3 对称性的最小能量异构体最接近球形芳香剂或超级芳香剂。在 D5h 键伸缩异构体中，电子结构显示出与理想球壳的较大偏差，具有杂化甚至球形谱系的逆转。结果表明，富勒烯笼的相对稳定性与芳香性没有很好的相关性，这与磁性是球形芳香性非常敏感的指标不同。 D3 笼中的超芳香抗磁性的特征是围绕整个笼的整体反变流。 D5h 笼中球形度的破坏导致局部顺向逆流。
The fullerene-50 is a 'magic number' cage according to the 2(N + 1)(2) rule. For the three lowest isomers of C50 with trigonal and pentagonal symmetries, we calculate the sphericity index, the spherical parentage of the occupied π-orbitals, and the current density in an applied magnetic field. The minimal energy isomer, with D3 symmetry, comes closest to a spherical aromat or a superaromat. In the D5h bond-stretch isomers the electronic structure shows larger deviations from the ideal spherical shells, with hybridisation or even reversal of spherical parentages. It is shown that relative stabilities of fullerene cages do not correlate well with aromaticity, unlike the magnetic properties which are very sensitive indicators of spherical aromaticity. Superaromatic diamagnetism in the D3 cage is characterized by global diatropic currents, which encircle the whole cage. The breakdown of sphericity in the D5h cages gives rise to local paratropic countercurrents.