Synthesis and charge density determination of 4,4-difluoro-3,5-diphenyl-4H-pyrazole and a hydrate derivative

We describe the synthesis of the title gem-difluoropyrazole and hydrate derivative by reaction of 3,5-diphenylpyrazole with the NF reagent Selectfluor. In addition to spectral characterization of the two products, X-ray crystal structures were determined and an analysis of the charge densities of each compound was carried out. It is proposed that a weakened NN bond in the parent pyrazole, perhaps a result of the gem-difluoro substitution, promotes formation of the hydrate. The title gem-difluoropyrazole is a potential precursor to gem-difluorinated cyclopropanes.