Tautomerism of 1-(2′,4′-dinitrophenyl)-3-methyl-2-pyrazolin-5-one: theoretical calculations, solid and solution NMR studies and X-ray crystallography

  title={Tautomerism of 1-(2′,4′-dinitrophenyl)-3-methyl-2-pyrazolin-5-one: theoretical calculations, solid and solution NMR studies and X-ray crystallography},
  author={Christophe Dardonville and Jos{\'e} Elguero and Isabel Rozas and Cristina Fern{\'a}ndez-casta{\~n}o and Concepci{\'o}n Foces-Foces and Isabel Sobrados},
  journal={New Journal of Chemistry},
To gain a better understanding of the tautomerism of 1-(2′,4′-dinitrophenyl)-3-methyl-2-pyrazolin-5-one, 2, different studies were performed. In order to simulate the gas phase, several MO calculations at the semiempirical (AM1 and PM3) and abinitio (HF/6-31G* and B3LYP/6-31G*) levels were carried out on the different tautomers of this compound and on those of the corresponding 1-phenyl derivative 4. The 1H and 13C NMR spectra were recorded in solution for compound 2. Finally, to investigate… Expand
The Condensation of (Chlorocarbonyl)phenyl Ketene with Bisnucleophiles. Synthesis of 4-Hydroxy-5-phenylpyro-[2,3-c]pyrazol-6-ones and Formation of Pyrazolo[1,2-a]pyrazole-triones by Hydrogen Exchange in Unstable Mesoionic Compounds
The addition of (chlorocarbonyl)phenyl ketene 2 to 5-alkylpyrazol-3(4H)-ones 1 led to the formation of 3-hydroxypyrazolo[1,2-a]pyrazole-dione/pyrazolo[1,2-a]pyrazole-trione derivatives 3. This isExpand
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Quantum-chemical investigation of structure and reactivity of pyrazol-5-ones and their thio- and seleno-analogs: X. Solvent effect on the chemical shifts of nuclei in the molecules of 3-methylpyrazol-5-ones and 1-phenyl-3-methylchalcogenepyrazol-5-ones and characteristics of tautomeric equilibrium i
By quantum-chemical DFT/GIAO method chemical shifts of all nuclei in the NMR spectra of 3-methylpyrazol-5-one and 1-phenyl-3-methylchalcogenopyrazol-5-ones in chloroform and dimethyl sulfoxide wereExpand
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Isomeric six- and five-membered (N2)-aromatics, 6-methylpyridazines and 5-vinylpyrazoles, which energetic topological aromaticity is comparable to that of benzene, are shown to be efficientlyExpand
Tautomerism in 4‐substituted 1‐phenyl‐3‐methyl‐pyrazolin‐5‐ones—a theoretical ab initio and 13C NMR study
The tautomeric equilibria between the CH, OH and NH forms in a series of 4-substituted 1-phenyl-3-methyl-pyrazolin-5-ones have been studied using ab initio calculations at various levels of theoryExpand
In the title pyrazolone derivative, C15H12N2O, the five-membered ring is approximately planar (r.m.s. deviation = 0.018 Å), and the N- and C-bound benzene rings are inclined to this plane [dihedralExpand
In the crystal of the title compound, C15H11ClN2O, the molecules are linked by C—H—H⋯O and weak C-H–O interactions and the N—N and C=O bond lengths are comparable to those reported for pyrazolone compounds. Expand
Self-assembly of NH-pyrazoles via intermolecular N-H.N hydrogen bonds.
It is shown that this is due to the internal pi-delocalization of the pyrazole ring, which can be hardly increased by the hydrogen-bond interaction, except in symmetrically 3,5-substituted pyrazoles which display N.N bonds. Expand
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The crystal and molecular structures of two nitrophenylpyrazolines have been determined. The geometries have been used as starting geometries for density functional theory (DFT) calculations. TheExpand
Structural characterization of hydrogen bonding for antipyrine derivatives: Single-crystal X-ray diffraction and theoretical studies
Objectives. The paper is devoted to the crystal structure characterization of 5-methyl-2-phenyl4H-pyrazol-3-one (compound I) and 2-(4-chlorophenyl)-5-methyl-4H-pyrazol-3-one (compound II). Methods .Expand


Crystal and Molecular Structure of Pyrazol-3-one Derivatives. II. 5-Amino-2,4-dihydro-2-phenyl-3H-pyrazol-3-one
The molecular and crystal structure of 5-amino-2, 4-dihydro-2-phenyl-3H-pyrazol-3-one was examined by the X-ray diffraction method to establish the predominant tautomeric form (the CH-form) due toExpand
Density Functional Study of the Radical Reactions of 3-Methyl-1-phenyl-2-pyrazolin-5-one (MCI-186): Implication for the Biological Function of MCI-186 as a Highly Potent Antioxidative Radical Scavenger
The radical reaction intermediates and products from the antioxidative radical scavenger MCI-186, 3-methyl-1-phenyl-2-pyrazolin-5-one (1), and its model system 1,3-dimethyl-2-pyrazolin-5-one (2) areExpand
The tautomerism of 1,2,3‐triazole, 3(5)‐methylpyrazole and their cations
The annular tautomerism of 1,2,3‐triazole and 3(5)‐methylpyrazole is discussed by means of a combination of theoretical calculations and experimental (ICR) gas‐phase basicities and acidities. In theExpand
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The acid/base behavior of above titled compounds is widely recognized for its importance to the life sciences. The gas- and aqueous-phase basicities of pyrimidine (1,3-diazine, I) are known to beExpand
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Abstract. High-level ab initio quantum mechanical methods have been used to analyze the tautomeric preferences in the gas phase and in aqueous solution of three important five-member heterocycles:Expand
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Experimental and theoretical estimates or the tautomeric equilibria in aqueous 3-hydroxypyrazole are discussed. The use or pK a data is shown to be critically dependent upon the inclusion orExpand
Use of crystallographic data in searching for isosteric replacements: Composite crystal-field environments of nitro and carbonyl groups†
(...) The composite environment may show strong systematic features which reflect the preferred interactions of the fonctional group. This is shown by test calculations on structures containing nitroExpand
Density-functional thermochemistry. III. The role of exact exchange
Despite the remarkable thermochemical accuracy of Kohn–Sham density‐functional theories with gradient corrections for exchange‐correlation [see, for example, A. D. Becke, J. Chem. Phys. 96, 2155Expand
Optimization of parameters for semiempirical methods. III Extension of PM3 to Be, Mg, Zn, Ga, Ge, As, Se, Cd, In, Sn, Sb, Te, Hg, Tl, Pb, and Bi
Using a recently developed procedure for optimizing parameters for semiempirical methods,1 PM3 has been extended to a total of 28 elements. Average ΔHf errors for the newly parameterized elements areExpand
Development of the Colle-Salvetti correlation-energy formula into a functional of the electron density.
  • Lee, Yang, Parr
  • Physics, Medicine
  • Physical review. B, Condensed matter
  • 1988
Numerical calculations on a number of atoms, positive ions, and molecules, of both open- and closed-shell type, show that density-functional formulas for the correlation energy and correlation potential give correlation energies within a few percent. Expand