Synthesis, characterization, crystal structure and theoretical studies of 4-[( E )-(3-chloro-4-hydroxyphenyl) diazenyl]-1, 5-dimethyl-2-phenyl-1, 2-dihydro-3 H -pyrazol-3-one

Abstract Crystals of new heterocyclic azo compound of 4-aminoantipyrine, 4-[( E )-(3-chloro-4-hydroxyphenyl)diazenyl]-1,5-dimethyl-2-phenyl-1,2-dihydro-3 H -pyrazol-3-one have been grown by slow evaporation method at room temperature and its structural characterization was performed by X- ray diffraction method. The spectroscopic characterization was also performed by FT-IR, UV–Vis, 13 C and 1 H NMR techniques. The compound crystallizes in the monoclinic C C space group with cell dimensions a = 12.4842 (13), b = 16.4492 (16), c = 8.3389 (8) and β = 102.698 (3)°. The phenyl ring attached to the pyrazolone moiety is disordered over two positions with an occupancy ratio 52:48. The components of the disorder were refined. DFT calculations have been performed by using B3LYP/6-311G (d,p) level basis set. The calculated vibrational frequency showed a red shift for C O and OH stretching. The natural bond orbital analysis of monomer, dimer and trimer structures reveals the absence of intramolecular hydrogen bonding; however intermolecular hydrogen bonding is observed. The cationic and anionic reactive sites of compound have been visualized on MEP surface.