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Aromaticity in Group 14 Homologues of the Cyclopropenylium Cation
Author(s) -
Fernández Israel,
Duvall Matthew,
IChia Wu Judy,
Schleyer Paul von Ragué,
Frenking Gernot
Publication year - 2011
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.201001392
Subject(s) - aromaticity , chemistry , isodesmic reaction , computational chemistry , molecule , wave function , ion , group (periodic table) , resonance (particle physics) , decomposition , density functional theory , crystallography , organic chemistry , atomic physics , physics
The nature of the bonding and the aromaticity of the heavy Group 14 homologues of cyclopropenylium cations E 3 H 3 + and E 2 H 2 E′H + (E, E′=C–Pb) have been investigated systematically at the BP86/TZ2P DFT level by using several methods. Aromatic stabilization energies (ASE) were evaluated from the values obtained from energy decomposition analysis (EDA) of charged acyclic reference molecules. The EDA‐ASE results compare well with the extra cyclic resonance energy (ECRE) values given by the block localized wavefunction (BLW) method. Although all compounds investigated are Hückel 4 n +2 π electron species, their ASEs indicate that the inclusion of Group 14 elements heavier than carbon reduces the aromaticity; the parent C 3 H 3 + ion and Si 2 H 2 CH + are the most aromatic, and Pb 3 H 3 + is the least so. The higher energies for the cyclopropenium analogues reported in 1995 employed an isodesmic scheme, and are reinterpreted by using the BLW method. The decrease in the strength of both the π cyclic conjugation and the aromaticity in the order C≫Si>Ge>Sn>Pb agrees reasonably well with the trends given by the refined nucleus‐independent chemical shift NICS(0) π zz index.