Conformations of silicon-containing rings. Part 3. Relative conformational energies of alkylated 1,3,5-trisilacyclohexanes as calculated from quantum chemical and molecular mechanics methods

I. Arnason*, E. Matern

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

Abstract

The relative energies of the basic conformations for five series of Si-alkylated derivatives of 1,3,5-trisilacyclohexane 1 with methyl, ethyl, i-propyl and t-butyl alkyl groups have been calculated using quantum chemical (QC) methods (HF and RI-DFT) and the MM3 force field. The results were compared to those from previous NMR investigations. It was found that the QC methods predict for all 1-mono-, cis-1,3-di and cis-cis-1,3,5-tri-alkylated 1 the chair(eq) to be the lowest energy conformation. The QC methods also predict a preference for twisted conformation in the cases of trans-1,3-di- and cis-trans-1,3,5-tri-t-butylated 1. The QC results confirm earlier predictions from the NMR data. In contrast, MM3 fails to calculate relative conformational energies properly. The reason for its failure is discussed.

Original languageEnglish
Pages (from-to)61-68
Number of pages8
JournalJournal of Molecular Structure: THEOCHEM
Volume544
Issue number1-3
DOIs
Publication statusPublished - 2 Jul 2001

Other keywords

  • 1,3,5-Trisilacyclohexane
  • Ab initio calculations
  • Conformational energies
  • Density functional calculations
  • Molecular mechanics

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