The serendipitous isolation of an unusual protonated bis(oxazoline) prompted us to discuss the role of H+ on the kinetics and thermodynamics of the equilibrium between its ketimine and enamine forms. X-ray diffraction analysis revealed that the protonated bis(oxazoline) is in the Z-enamine form, the unipositive charge is counterbalanced by [(FeCl3)2O]2- and [FeCl4]- anions. DFT calculation at the BP86/TZVP level showed that relative stability of enamine tautomer versus ketimine tautomer increases with the proton- ation of the nitrogen atom of the oxazolidine ring. At the same time, the barrier energy of tautomerism decreases.
Tautomerism in bis(oxazolines): an experimental and theoretical study of proton transfer in 1,1-bis(4,4-dimethyl-1,3-oxazolin-2-yl)-ethane
BERTOLASI, Valerio
2011
Abstract
The serendipitous isolation of an unusual protonated bis(oxazoline) prompted us to discuss the role of H+ on the kinetics and thermodynamics of the equilibrium between its ketimine and enamine forms. X-ray diffraction analysis revealed that the protonated bis(oxazoline) is in the Z-enamine form, the unipositive charge is counterbalanced by [(FeCl3)2O]2- and [FeCl4]- anions. DFT calculation at the BP86/TZVP level showed that relative stability of enamine tautomer versus ketimine tautomer increases with the proton- ation of the nitrogen atom of the oxazolidine ring. At the same time, the barrier energy of tautomerism decreases.File in questo prodotto:
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