How aromatic are large (4n + 2)π annulenes?

Organic Letters

Volumn 5, Issue 6, 2003, Pages 865-868

  Wannere, Chaitanya S ^a   Von Ragué Schleyer, Paul ^a  

^a UNIVERSITY OF GEORGIA   (United States)

Author keywords

[No Author keywords available]

Indexed keywords

ANNULENE DERIVATIVE; AROMATIC COMPOUND;

ARTICLE; CHEMICAL STRUCTURE; ELECTRON; ENERGY; MAGNETISM; PROTON NUCLEAR MAGNETIC RESONANCE; THEORY;

EID: 0042048198     PISSN: 15237060     EISSN: None     Source Type: Journal    
DOI: 10.1021/ol027571b     Document Type: Article

References (39)

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26. Schleyer, P. v. R.; Pühlhofer, F. Org. Lett. 2002, 4, 2873. The ISE method compares the computed energy of a methyl derivative of a given aromatic system with its structurally closely related nonaromatic exocyclic methylene isomer. See Scheme 1. ISEs were computed at three different levels: HF/6-31G*//HF/6-31G*, B3LYP/6-31G*//HF/6-31G*, and B3LYP/6-31G*//B3LYP/6-31G* designated as HF/HF, B3LYP/HF, and B3LYP/B3LYP, respectively, in subsequent text.
27. Geometry optimizations, energy evaluations (with ZPE corrections), and frequency analyses, of all the structures in Scheme 1 and in Table 1, were carried out first at HF/6-31G* and then at B3LYP/6-31G*, using Gaussian 98 (reference in Supporting Information). Planar conformations of methyl annulenes and their respective nonaromatic isomers were forced, in order to compute the ISEs and Λ, since the ISEs using their nonplanar analogues were not different (e.g., ISE of 22.2 for nonplanar vs 27.4 kcal/mol for planar methyl[18]annulene at B3LYP/6-31G*).
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35. A evaluated at CSGT-B3LYP/6-31+G*//B3LYP/6-311+G**.
36. 1H NMR chemical shift employed the PW-91 functional, the IGLO-III TZ2P basis set, and the Pipek - Mezey σ,π-localization available in the demon NMR program.
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