Aromaticity of the doubly charged [8]circulenes
| Autor: | Rashid R. Valiev, Nataliya N. Karaush, Boris F. Minaev, Gleb V. Baryshnikov, Dage Sundholm |
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| Přispěvatelé: | Department of Chemistry |
| Rok vydání: | 2016 |
| Předmět: |
MAGNETICALLY INDUCED CURRENTS
ORGANIC SEMICONDUCTORS NICS INDEPENDENT CHEMICAL-SHIFTS 116 Chemical sciences General Physics and Astronomy Electronic structure TRANSITION-METAL CLUSTERS циркулены 010402 general chemistry Ring (chemistry) 114 Physical sciences 01 natural sciences MOLECULES Computational chemistry циклены Molecule RING CURRENT Physical and Theoretical Chemistry Ring current ароматичность 010405 organic chemistry Chemistry GIMIC CHARACTERIZATION Chemical shift Aromaticity INDUCED CURRENT DENSITIES 0104 chemical sciences ионы ELECTRONIC-STRUCTURE Proton NMR Antiaromaticity |
| Zdroj: | Physical chemistry chemical physics. 2016. Vol. 18, № 13. P. 8980-8992 |
| ISSN: | 1463-9084 |
| Popis: | Magnetically induced current densities and current pathways have been calculated for a series of fully annelated dicationic and dianionic tetraphenylenes, which are also named [8]circulenes. The gauge including magnetically induced current (GIMIC) method has been employed for calculating the current density susceptibilities. The aromatic character and current pathways are deduced from the calculated current density susceptibilities showing that the neutral [8]circulenes have two concentric pathways with aromatic and antiaromatic character, respectively. The inner octatetraene core (the hub) is found to sustain a paratropic (antiaromatic) ring current, whereas the ring current along the outer part of the macrocycle (the rim) is diatropic (aromatic). The neutral [8]circulenes can be considered nonaromatic, because the sum of the ring-current strengths of the hub and the rim almost vanishes. The aromatic character of the doubly charged [8]circulenes is completely different: the dianionic [8]circulenes and the OC-, CH-, CH2-, SiH-, GeH-, SiH2-, and GeH2-containing dicationic species sustain net diatropic ring currents i.e., they are aromatic, whereas the O-, S-, Se-, NH-, PH- and AsH-containing dicationic [8]circulenes are strongly antiaromatic. The present study also shows that GIMIC calculations on the [8]circulenes provide more accurate information about the aromatic character than that obtained using local indices such as nuclear-independent chemical shifts (NICSs) and H-1 NMR chemical shifts. |
| Databáze: | OpenAIRE |
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