The conformational analysis of push-pull enaminones using Fourier transform IR and NMR spectroscopy, and quantum chemical calculations. V. alpha-Methyl-, fluorine-beta-N,N-dimethylaminovinyl trifluoromethyl ketones

作者：Vdovenko Sergey I^*; Gerus Igor I; Zhuk Yuri I; Kukhar Valery P; Roeschenthaler Gerd Volker

来源：Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy , 2014, 131: 94-101.

DOI：10.1016/j.saa.2014.04.053

• NMR and IR-spectra
• Conformational analysis
• Enaminoketones
• DFT calculations

IR Fourier spectra of two enaminoketones with general formula F3C-CO-CR=CH-N(CH3)(2), R = F (DMTFBN); R = CH3, (DMTMBN) were studied in various pure solvents. For comparison results of earlier investigated enaminoketone R = H (DMTBN) was also presented. On the basis of NMR and IR spectra it was shown that enaminoketones DMTBN, DMTFBN and DMTMBN presented in solutions as equilibrium of two conformers, (E-s-Z)reversible arrow (E-s-E) (for DMTFBN these conformers are denoted as (Z-s-Z) and (Z-s-E), respectively). DFT calculations were carried out to evaluate relative energy and dipole moment of each spatial form. It was shown that %26apos;closed-ring%26apos; complex formation between (E-s-Z) and (E-s-E) conformers of DMTBN accounts for discrepancies between DFT calculations of conformer relative energies and experimentally evaluated enthalpies of (E-s-Z) (E-s-E) equilibrium. In a-substituted DMTFBN and DMTMBN, where formation of %26apos;closed-ring%26apos; complex was impossible we did not observe such discrepancies. For both (E-s-Z) and (E-s-E) conformers of the DMTBN and DMTMBN the main influence on the (v) over tilde (C=0) vibrations has the solvent%26apos;s hydrogen bond donor (HBD) acidity, whereas for the DMTFBN an influence of the solvent%26apos;s polarity/polarizability dominated.

• 出版日期2014-10-15