Synthesis, characterization, and crystal structures of new 3,5-diaryl-1H-pyrazoles

Seven new 3,5-diaryl-1H-pyrazoles were synthesized by the condensation of 1,3-diketones with hydrazine in ethanol, and characterized. The crystal structures for 3(5)-(4-tert-butylphenyl)-5(3)-(4-fluorphenyl)-1H-pyrazole (5) and 3-(4-tert-butylphenyl)-5-(6-methoxy-naphthalen-2-yl)-1H-pyrazole (7) have been determined by X-ray crystal structure analysis. The N–H…N intermolecular hydrogen bonds join the molecules into dimers. The NH proton of 5 is disordered, and its dimer is formed by the tautomers 5a5b or 5b5a. Compound 7 only exists as a 7a tautomer, and its dimer consists of the tautomers 7a7a.