Spectroscopic evidence for medium controlled hydrogen bond inhibition of resonance delocalization of charge in complexes of tetrabutylammonium fluoride with phenols
✍ Scribed by James H. Clark; David G. Cork; Julie A. Tinsdale
- Publisher
- Elsevier Science
- Year
- 1986
- Tongue
- English
- Weight
- 275 KB
- Volume
- 42
- Category
- Article
- ISSN
- 1386-1425
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✦ Synopsis
Infrared spectra of tetrabutylammonium fluoride complexes of both 4-cyanophenol and methyl-4-hydroxybenzoate but not 3-cyanophenoi reveal the presence of two distinct types of hydrogen bond corresponding to charge localized and partially charge delocalized forms. The latter only occur in polar aprotic protophilic solvents at low temperatures. The activation energies for the interconversion of the two forms reflect the relative abilities of the two groups to delocalize charge through resonance. The chemical shifts of the aromatic protons of the complexes are also medium dependent although the precise nature of this medium dependence is less easily understood.