𝔖 Bobbio Scriptorium
✦   LIBER   ✦

Separation of the energetic and geometric contributions to aromaticity. Part VI. Changes of the aromatic character of the rings in naphthalene, anthracene, phenanthrene and pyrene derivatives induced by the charged substituent CH2+

✍ Scribed by Tadeusz M. Krygowski; Michal K. Cyrański; Kazuhide Nakata; Mizue Fujio; Yuho Tsuno

Publisher
Elsevier Science
Year
1997
Tongue
French
Weight
703 KB
Volume
53
Category
Article
ISSN
0040-4020

No coin nor oath required. For personal study only.

✦ Synopsis

Ab initio 6-3 IG* optimised geometries of naphthalene, anthracene, phenanthrene, pyrene and all their CH: + mono-substituted derivatives have been examined in respect to estimate the changes of their aromatic character due to these kinds of substitution. CH2 ÷ substitnent attached to aromatic hydrocarbons causes dramatic changes in their molecular geometry. This implies great changes in both local (i.e. referring to a single ring) and global aromaticity. The substituted rings always lose some part of their original aromatic character, but if the position of the substitution permits formation of the quinoidal structure via a short CC bond which is spread over the larger part of the molecule, the decrease of aromatic character is greater than in the other cases. Formation of quinoidal structures in a molecule leads to a long-range intramolecular charge transfer.

📜 SIMILAR VOLUMES

Separation of the energetic and geometri
Separation of the energetic and geometric contributions to aromaticity. Part VII. Changes of the aromatic character of the rings in naphthalene induced by the charged substituent CH2+. The dependence on the position of the substitution, torsion angle and the exocyclic bond length variation
✍ Tadeusz M. Krygowski; Michal K. Cyrański; Kazuhide Nakata; Mizue Fujio; Yuho Tsu 📂 Article 📅 1998 🏛 Elsevier Science 🌐 French ⚖ 490 KB

The l-and 2-CHz+ derivatives are studied in terms of variation of the C-C exocyclic bond and the torsion around it in order to show the stractural consequences in naphthalene moiety. It results that rotation around and elongation of this bond lead to the fluctuation of the electronic charge at atoms

Separation of the energetic and geometri
Separation of the energetic and geometric contribution to aromaticity. Part X. The case of benzene rings in fused polycyclic benzenoid hydrocarbons
✍ MichałK. Cyrański; Tadeusz M. Krygowski 📂 Article 📅 1998 🏛 Elsevier Science 🌐 French ⚖ 299 KB

Abstraa Eight aromaticity indices were estimated by the application of the bond lengths of 18 benzene tings taken from 10 benzenoid hydrocarbons (benzene, naphthalene, anthraccnc, tetracene, phenanthrenc, clh-ysene, triphenylene, pyrene, perylene and coroncne) computed by ab initio at RHF 6-31G\*\*