4-Nitro-phenol-piperazine (2/1)

In the title adduct, C6H5NO3·0.5C4H10N2, the piperazine ring possesses inversion symmetry and has a chair conformation. Its mean plane makes a dihedral angle of 65.45 (7)° with the 4-nitro-phenol ring. In the crystal, the piperazine ring is linked to two 4-nitro-phenol mol-ecules via O-H⋯N hydrogen bonds. The mol-ecules are also linked via bifurcated N-H⋯(O,O) hydrogen bonds involving the NO2 O atoms, forming a two-dimensional network lying parallel to (102). The networks are linked via C-H⋯O hydrogen bonds, forming a three-dimensional structure.