Hydrogen-bonded chains in 3,5-bis(4-fluorophenyl)-1-phenyl-1H-pyrazole and complex hydrogen-bonded sheets in (5RS,6SR)-6-(4-fluorobenzoyl)-5-(4-fluorophenyl)-2-(4-hydroxyphenyl)-5,6-dihydro-4H-1,3,4-oxadiazine N,N-dimethylformamide monosolvate.

Two different heterocycles, a pyrazole and an oxadiazine, are formed by the reactions of a common precursor, (2RS,3SR)-2,3-dibromo-1,3-bis(4-fluorophenyl)propan-1-one, with different simple hydrazines. In 3,5-bis(4-fluorophenyl)-1-phenyl-1H-pyrazole, C(21)H(14)F(2)N(2), (I), formed using phenylhydrazine, there is some aromatic-type delocalization in the pyrazole ring, and the molecules are linked into simple chains by a single C-H...π(arene) hydrogen bond. The reaction with 4-hydroxybenzohydrazide gives (5RS,6SR)-6-(4-fluorobenzoyl)-5-(4-fluorophenyl)-2-(4-hydroxyphenyl)-5,6-dihydro-4H-1,3,4-oxadiazine, which was crystallized from N,N-dimethylformamide to give the monosolvate, C(22)H(16)F(2)N(2)O(3) · C(3)H(7)NO, (II), in which the solvent molecule is disordered over two sets of atomic sites having occupancies of 0.557 (10) and 0.443 (10). The oxadiazine molecules in (II) are linked by a combination of N-H...N and C-H...O hydrogen bonds to form complex sheets, having the hydrogen bonds in the central layer and with the solvent molecules attached at the outer faces by O-H...O hydrogen bonds.