(E)-3,5-Dimethyl-1-p-tolyl-4-(p-tolyl-diazen-yl)-1H-pyrazole

A family of substituted hydrazonoisoxazolones with potential biological properties

The synthesis and characterization of a family of isoxazolones were performed. X-Ray diffraction over three structures was performed. All the compounds showed antineoplastic activity.

Structural aspects of two α-dihydrazones displaying a complete survey of intermolecular interactions

The compounds (2′E,2′E)-2,2′-(propane-1,2-diylidene)bis[1-(2-nitrophenyl)hydrazine], C15H14N6O4, (I), and (2Z,3Z)-ethyl 3-[2-(2-nitrophenyl)hydrazinylidene]-2-[2-(4-nitrophenyl)hydrazinylidene]butanoate tetrahydrofuran hemisolvate, C18H18N6O6·0.5C4H8O, (II), are puzzling outliers deviating from a general synthetic route aimed at the preparation of substituted pyrazoles. Possible reasons for this outcome, which is exceptional in an otherwise firmly established synthetic procedure, are analyzed. Compound (I) is unsolvated, while compound (II) crystallizes with a tetrahydrofuran solvent molecule lying on an inversion centre. The ethoxycarbonyl chain of (II), in turn, appears disordered into two equally populated (50%) moieties. In both structures, a plethora of different commonly occurring weak intermolecular interactions [viz. π(phenyl)...π(phenyl), π(C=N)...π(C=N), π(phenyl)...π(C=N), N—H...O and C—H...O] appear responsible for the crystal stability. Much less common are the short O(nitro)...O(nitro) contacts which are observed in the structure of (I), an example of unusual `electron donor–acceptor' (EDA) interactions.

(Z)-1-(2-Chloro-phen-yl)-3-methyl-4-[2-(4-nitro-phen-yl)hydrazin-1-yl-idene]-1H-pyrazol-5(4H)-one

There are two independent mol­ecules, A and B, in the asymmetric unit of the title compound, C₁₆H₁₂ClN₅O₃. The relative orientations of the chloro­phenyl ring with respect to the pyrazole ring in the two crystallographically independent mol­ecules are different, and their corresponding dihedral angles are −53.3 (2) and 114.09 (18)° in mol­ecules A and B, respectively. There are two strong intramolecular N—H⋯O hydrogen bonds, and two weak intramolecular C—H⋯O and C—H⋯Cl hydrogen bonds. The crystal packing is constructed by weak C—H⋯O and N—H⋯O inter­actions, and two π–π stacking inter­actions [centroid–centroid distances = 3.7894 (9) and 3.5719 (10) Å], forming a mol­ecular ladder along the a axis.