3,3',5,5'-tetramethyl-4,4'-bipyrazole-pentafluorophenol (2/3).

In the title compound, 2C10H14N4.3C6HF5O, one of the pentafluorophenol molecules resides on a mirror plane bisecting the O...F axis. The components aggregate by N-H...N, N-H...O and O-H...N hydrogen bonds involving equal disordering of the H atoms into molecular ensembles based on a 2:1 pyrazole-phenol cyclic pattern [O...N = 2.7768 (16) A and N...N = 2.859 (2) A], crosslinked into one-dimensional columns via hydrogen bonding between the outer pyrazole groups and additional pentafluorophenol molecules. The latter yields a 1:1 pyrazole-phenol catemer with alternating strong O-H...N [2.5975 (16) A] and weaker N-H...O [2.8719 (17) A] hydrogen bonds. This is the first reported molecular adduct of a pentafluorinated phenol and a nitrogen base, and suggests the utility of highly acidic phenols and pyrazoles for developing hydrogen-bonded cocrystals.