Substituent effect on the aromaticity of the silolide anion

Csaba Fekete, Ilona Kovács, László Könczöl, Zoltán Benkő, László Nyulászi

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Abstract

The effect of the substituents on the planarity and aromaticity of the silolide anion was studied computationally. It was revealed that π-electron acceptor groups (e.g., silyl or trimethylsilyl) at the α position of the ring reduce substantially the inversion barrier about the central silicon increasing the aromaticity according to isomeric stabilization energy (ISE) and NICS values. In the planar and highly aromatic silolide anions, the mesomeric structures with the largest weight exhibit a Si=C double bond and a negative charge which is located at the α or β carbons based on NRT calculations. 2,5-disilylsilacyclopentadienides coordinated by naked Li + have planar minima, however, further coordination by THF molecules (as in a solution) reduces somewhat the flattening of the silicon pyramid. NMR calculations were carried out to understand the connection between the 29 Si chemical shift and the aromaticity of the ring. It was revealed that the commonly accepted charge transfer-chemical shift relationship is strongly influenced by the substituents and the counter cation. THF complexation of the Li counter cation has a small influence on the NMR shift.

Original languageEnglish
Pages (from-to)377-387
Number of pages11
JournalStructural Chemistry
Volume25
Issue number1
DOIs
Publication statusPublished - Feb 2014

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Keywords

  • Aromaticity
  • Density functional calculations
  • Silolide
  • Silyl substitution
  • Solvent effect

ASJC Scopus subject areas

  • Condensed Matter Physics
  • Physical and Theoretical Chemistry

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