Spectroscopy, Crystal and Molecular Structures of New 4-Acylpyrazolone Dinitrophenylhydrazones

Abstract

Still looking at the development of new materials with unique properties and taking advantage of the nucleophilic properties of amines to form stable azomethines, dinitrophenylhydrazine was reacted with 4-ethyl-5-methyl-2-phenyl-pyrazol-3-one and then with 4-propyl-5-methyl-2-phenyl-pyrazol-3-one to get 4-ethyl-5-methyl-2-phenyl-pyrazol-3-one dinitrophenylhydrazone (Empp-Dh) and 4-propyl-5-methyl-2-phenyl-pyrazol-3-one dinitrophenylhydrazone (Pmpp-Dh), respectively, via a simple condensation reaction in a one-pot synthesis system. Careful interpretations of results from elemental analysis, mass and NMR spectroscopy were in agreement with single-crystal X-ray diffraction data. Reported Schiff bases in their single-crystal solid state exist in imine keto tautomer form, each crystallizing in a monoclinic crystal system, with a space group of C2/c (No. 15) in Empp-Dh and P21/c (No. 14) in Pmpp-Dh. They have extensive intra- and inter-molecular hydrogen as well as C–H···π-ring interactions.

Keywords

• acylpyrazolone
• dinitrophenylhydrazone
• Schiff base
• monoclinic
• single crystal
• spectroscopy
• chemical shift