A different story of π-delocalization - The distortivity of π-electrons and its chemical manifestations

Chemical Reviews

Volumn 101, Issue 5, 2001, Pages 1501-1539

  Shaik, Sason ^a   Shurki, Avital ^a   Danovich, David ^a   Hiberty, Philippe C ^b  

^a HEBREW UNIVERSITY OF JERUSALEM   (Israel)

^b UNIVERSITÉ PARIS SUD   (France)

Author keywords

[No Author keywords available]

Indexed keywords

DENSITY FUNCTIONAL THEORY (DFT); ELECTRONIC DELOCALIZATION;

BUTADIENE; CHEMICAL BONDS; DIAMAGNETISM; ELECTRON RESONANCE; ELECTRON TRANSITIONS; ELECTRONIC STRUCTURE; GROUND STATE; MOLECULAR VIBRATIONS; MOLECULES; NATURAL FREQUENCIES; NUCLEAR MAGNETIC RESONANCE SPECTROSCOPY; QUANTUM THEORY; X RAY DIFFRACTION ANALYSIS;

BENZENE;

EID: 0035353542     PISSN: 00092665     EISSN: None     Source Type: Journal    
DOI: 10.1021/cr990363l     Document Type: Review

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361. ST. The ratio between the gaps is then (2N + 1)/(2N). This ratio is smaller than the ratio (≥2) between the energy difference between the twin states at the symmetric geometry. This is due to the fact that the vertical resonance energy is much larger for the aromatic species. It follows, therefore, that the curvatures of the twin states at the symmetric geometry will be significantly larger for the antiaromatic species.
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367. Using the QC state approach (ref 6), we find that B3LYP calculations of benzene give virtually the same distortivity as the π-CISD level used in ref 6.
368. 1g symmetry, and therefore, the circular flow of the electrons is interrupted. The mixing occurs, however, in the presence of an external magnetic field and induces the paramagnetic ring currents.