1 H nuclear magnetic resonance and molecular orbital studies of the structure and internal rotations in ethylbenzene
1987; NRC Research Press; Volume: 65; Issue: 4 Linguagem: Inglês
10.1139/v87-147
ISSN1480-3291
AutoresTed Schaefer, Glenn H. Penner, Rudy Sebastian,
Tópico(s)Molecular Spectroscopy and Structure
ResumoRather extensive geometry-optimized computations at the STO-3G, 4-21G, 4-31G, and 6-31G levels of abinitio molecular orbital theory suggest that the fourfold component of the barrier to internal rotation about the C sp 2 —C sp 3 bond in ethylbenzene amounts to about 20% of the twofold component. The 1 H nuclear magnetic resonance spectral parameters, extracted by complete analyses of the spectra arising from the ten protons, are reported for ethylbenzene in acetone-d 6 , CCl 4 , CS 2 , and perfluoromethylcyclohexane solutions. The long-range proton–proton spin–spin coupling constants demonstrate that the internal barrier is insensitive to the polarity of the solvent, in contrast to polar solute molecules such as benzyl fluoride. The coupling constants do not support a dependence of the internal barrier on the internal pressure of the solvent.
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