Tautomerism of pyridinylbutane-1,3-diones: An NMR and DFT study

Poul Erik Hansen*, Vahidreza Darugar, Mohammad Vakili, Fadhil S. Kamounah

*Corresponding author

Publikation: Bidrag til tidsskriftTidsskriftartikelForskningpeer review


The three possible 1-(n-pyridinyl)butane-1,3-diones (nPM) have been synthesized. Structures, tautomerism, and conformations are investigated by means of DFT calculations. 1H and 13C NMR spectra are assigned, and deuterium isotope effects on 13C chemical shifts have been measured. Analysis of the isotope effects leads to the equilibrium constants of the keto–enol tautomers. Some interesting differences are seen between the three compounds and the phenyl analogs. The isotope effects can also rank the hydrogen bonds of the compounds, with the one with nitrogen in the three positions of the pyridine ring as the weakest. Structures, conformers, energies, and NMR nuclear shieldings are calculated using DFT calculations at the B3LYP/6-311++G(d,p) level.

TidsskriftMagnetic Resonance in Chemistry
Udgave nummer6
Sider (fra-til)356-362
StatusUdgivet - jun. 2023


  • DFT calculations
  • hydrogen bonding
  • isotope effects on chemical shifts
  • NMR
  • pyridinylbutane-1,3-diones
  • tautomerism
  • β-diketones

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