Are 1,4-Dihydropyrazines Antiaromatic? Ab initio Study of 1,4-Dihydropyrazines and Their Tetrahydro Derivatives

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Title:Are 1,4-Dihydropyrazines Antiaromatic? Ab initio Study of 1,4-Dihydropyrazines and Their Tetrahydro Derivatives
Creators:
Vlček, Pavel
Havlas, Zdeněk
Pavlíček, Zdeněk
Journal or Publication Title:
Collection of Czechoslovak Chemical Communications, 64, 4, pp. 633-648
Uncontrolled Keywords:<i>Ab initio</i> calculations, Isodesmic energy, Aromaticity, Pyrazines, Antiaromaticity, DFT calculations

Abstract

A set of twenty molecules containing 1,4-dihydro- or tetrahydropyrazine ring was calculated using <i>ab initio</i> methods. This set also includes previously prepared diacetyl- or disilyldihydropyrazines. Structures of 1,4-dihydropyrazine derivatives are strongly dependent on ring substituents and change from planar to heavily distorted boat conformations. In the planar and near-planar structures of some 1,4-diacyl- or 1,4-diformyl-1,4-dihydropyrazines, conjugation of nitrogen lone pairs and ring bond π electrons is small. Structures, bond lengths and bond orders of 1,4-dihydropyrazines and their tetrahydro derivatives are similar. The isodesmic energy shows tendency rather to aromatic then to antiaromatic conjugation. On the basis of structural, electronic and energy arguments it is proposed to classify 1,4-dihydropyrazines as nonaromatic compounds. <p>

Title:Are 1,4-Dihydropyrazines Antiaromatic? Ab initio Study of 1,4-Dihydropyrazines and Their Tetrahydro Derivatives
Creators:
Vlček, Pavel
Havlas, Zdeněk
Pavlíček, Zdeněk
Uncontrolled Keywords:<i>Ab initio</i> calculations, Isodesmic energy, Aromaticity, Pyrazines, Antiaromaticity, DFT calculations
Divisions:Life and Chemical Sciences > Institute of Organic Chemistry and Biochemistry > Collection of Czechoslovak Chemical Communications
Journal or Publication Title:Collection of Czechoslovak Chemical Communications
Volume:64
Number:4
Page Range:pp. 633-648
ISSN:0010-0765
E-ISSN:1212-6950
Publisher:Institute of Organic Chemistry and Biochemistry
Related URLs:
URLURL Type
http://dx.doi.org/10.1135/cccc19990633UNSPECIFIED
ID Code:1505
Item Type:Article
Deposited On:06 Feb 2009 17:10
Last Modified:06 Feb 2009 16:10

Citation

Vlček, Pavel; Havlas, Zdeněk; Pavlíček, Zdeněk (1999) Are 1,4-Dihydropyrazines Antiaromatic? Ab initio Study of 1,4-Dihydropyrazines and Their Tetrahydro Derivatives. Collection of Czechoslovak Chemical Communications, 64 (4). pp. 633-648. ISSN 0010-0765

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