Wydział Chemii

Aleksander Filarowski

Aleksander Koll

Maria Rospenk

Iwona Król-Starzomska

Poul Erik Hansen

2005

Journal of Physical Chemistry A

109

4464-4473

10.1021/jp0445977

Naukowa

Angielski

Artykuł

A series of sterically hindered o-hydroxy Schiff bases derived from o-hydroxyaceto- and benzophenones with very short intramolecular hydrogen bonds were described qualitative and quantitatively by deuterium isotope effects on ¹³C chemical shift, ⁿΔC(XD), ⁿΔF(XD), ¹J(N,H) coupling constants, δNCH₃ chemical shifts and UV spectra. All the investigated compounds are found to be tautomeric. The tautomeric character is described by the signs of the deuterium isotope effects on the ¹³C chemical shifts. For the 3-nitro-5-chloro derivatives at low temperature, the equilibrium is shifted almost fully toward the proton transferred form in CD₂Cl₂. Intrinsic deuterium isotope effects on chemical shifts of these compounds as well as ¹J(N,H) coupling constants suggest that a zwitterionic resonance form is dominant for the proton transferred form. Structures, ¹H, ¹⁹F, and ¹³C chemical shifts, and deuterium isotope effects on ¹³C chemical shifts are calculated by ab initio methods. The potential energy functions and the total deuterium isotope effects are calculated, and they are shown to correspond well with the experimental findings.

Equilibrium, Hydrogen isotopes, Isotope effects, Reaction mechanisms, Solvents

https://doi.org/10.1021/jp0445977

https://www.acs.org/content/acs/en.html