title: On substituted pyrazole derivatives. I. 3-Methyl-4-[(Z)-2-(4-methylphenyl)hydrazin-1-ylidene]-1-(3-nitrophenyl)-1H-pyrazol-5(4H)-one and 3-methyl-4-[(Z)-2-(4-methylphenyl)hydrazin-1-ylidene]-1-[4-(trifluoromethyl)phenyl]-1H-pyrazol-5(4H)-one.
abstract: The title substituted pyrazole derivatives, C17H15N5O3 and C18H15F3N4O, share most of their molecular features, in particular the hydrazinylidene (-HN-N=) rather than the diazene (-N=N-) tautomeric form, and differ only in the substituents (NO2 and CF3) on one of the outer phenyl rings. The molecular units are basically planar, with the rotation of the phenyl rings being hindered by the presence of two intramolecular hydrogen bonds having the keto O atom as acceptor. In both structures, the packing is governed by weak C-H...O, C-H...π and π-π interactions. The subtle way in which minor structural differences lead to rather different supramolecular structures is analysed.
authors.affiliation: Departamento de Ciencias Físicas, Universidad Andrés Bello, República 220, Santiago de Chile, Chile.
authors.forename: Luis
authors.initials: L
authors.lastname: Alvarez-Thon
authors.affiliation: Instituto de Ciencias Químicas, Universidad Austral de Chile, Avenida Los Robles s/n, Campus Isla Teja, Casilla 567, Valdivia, Chile.
authors.forename: Carlos
authors.initials: C
authors.lastname: Bustos
authors.affiliation: Institut de Ciència de Materials de Barcelona (ICMAB-CSIC), Campus UAB, 08193 Bellaterra, Spain.
authors.forename: Elies
authors.initials: E
authors.lastname: Molins
authors.affiliation: Departamento de Física, Facultad de Ciencias Físicas y Matemáticas, Universidad de Chile, Santiago de Chile, Chile.
authors.forename: Maria Teresa
authors.initials: MT
authors.lastname: Garland
authors.affiliation: Gerencia de Investigación y Aplicaciones, Centro Atómico Constituyentes, Comisión Nacional de Energía Atómica, Buenos Aires, Argentina.
authors.forename: Ricardo
authors.initials: R
authors.lastname: Baggio
mesh_terms: D018360:Crystallography, X-Ray; D006860:Hydrogen Bonding; D007094:Imides / Q000737:chemistry*; D015394:Molecular Structure; D009574:Nitro Compounds / Q000737:chemistry*; D011720:Pyrazoles / Q000737:chemistry*; D047069:Pyrazolones / Q000737:chemistry*
chemical_list: C000593276:3-methyl-4-((Z)-2-(4-methylphenyl)hydrazin-1-ylidene)-1-(3-nitrophenyl)-1H-pyrazol-5(4H)-one; D007094:Imides; D009574:Nitro Compounds; D011720:Pyrazoles; D047069:Pyrazolones; C038867:diazene
keywords: crystal structure; pharmaceutical compounds; resonance-assisted hydrogen bond (RAHB); substituted pyrazoles; weakly bound supramolecular structures