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Internet Electronic Journal of Molecular Design - IEJMD, ISSN 1538-6414, CODEN IEJMAT
| ABSTRACT - Internet Electron. J. Mol. Des. November 2002, Volume 1, Number 11, 603-609 |
Aromatization Energy of Cyclopropenyl Cation
Cherumuttathu H. Suresh and Nobuaki Koga
Internet Electron. J. Mol. Des. 2002, 1, 603-609
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Abstract:
A radical based homodesmotic reaction (HDR) is designed for the
accurate calculation of the aromatic stabilization energy of
cyclopropenyl cation. The energy of the HDR (ΔE) accounts for the
energy released when the cyclic 2π electron cationic conjugation is
changed to a linear 2π electron cationic conjugation. In other words,
ΔE corresponds to the aromatic stabilization energy of cyclopropenyl
cation. The value of the aromatic stabilization at G2 level is found to
be 127.0 kJ/mol. This stabilization energy is much smaller as
compared to the value of 247.3 kJ/mol calculated by Glukhovtsev et
al. in 1996 using a reaction falsely described as a homodesmotic
reaction. In fact, their value accounted mainly the total π electron
conjugation energy of (C3H3)+
and not to its aromatic stabilization.
B3LYP/6-31G(d,p) and G2 level calculations on homodesmotic
reaction were used in this study. The aromatic stabilization energy of
cyclopropenyl cation at B3LYP/6-31G(d,p) and G2 levels are,
respectively, 115.4 and 127.0 kJ/mol. A new homodesmotic reaction is
designed for the accurate estimation of the aromatic stabilization
energy of cyclopropenyl cation.
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