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)(2)O](2-) and [FeCl4](-) anions. DFT calculation at the BP86/TZVP level showed that relative stability of enamine tautomer versus ketimine tautomer increases with the protonation 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
MILIONE, Stefano;
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)(2)O](2-) and [FeCl4](-) anions. DFT calculation at the BP86/TZVP level showed that relative stability of enamine tautomer versus ketimine tautomer increases with the protonation 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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