1,4-Bis[(1H-pyrazol-1-yl)methyl]benzene

In the title compound, C14H14N4, the center of the phenylene group is a crystallographic center of inversion. The compound is composed of three aromatic rings displaying a Z-like conformation. The dihedral angle between the pyrazole rings and the central phenyl ring is 83.84 (9)°.

In the title compound, C 14 H 14 N 4 , the center of the phenylene group is a crystallographic center of inversion. The compound is composed of three aromatic rings displaying a Z-like conformation. The dihedral angle between the pyrazole rings and the central phenyl ring is 83.84 (9) .

Comment
Over the past few years, efforts have been focused on the investigation of coordination polymers with flexible ligands.
Flexbile ligands with two or more pyrazolyl moieties such as 1,4-bis[(1H-pyrazol-1-yl)-methyl]-benzene find numerous applications in constructing metal-organic coordination polymers (Chang et al. 1993;Hou et al. 2010;Liu et al. 2011). The crystal structure of the title compound including two water molecules of hydration has previously been described (Shi et al. 2009). We report here the crystal structure of the title compound without any solvent molecules in the crystal lattice.
In (I), the center of the phenylene group is an inversion centre, so that the asymmetric unit consists of one-half of the title compound ( Fig. 1). 1,4-Bis[(1H-pyrazol-1-yl)-methyl]-benzene is composed of three aromatic rings, displaying a Z shape, with the pyrazole rings on opposite sides of the plane of the phenyl ring. The whole molecule is nonplanar, the dihedral angle of the pyrazoles with respect to the central phenyl group are 83.84 (9)°. The average bond distances and angles for the pyrazole ring are in agreement with those of previously reported related pyrazole complexes and the hydrated title compound (Liu et al.2011;Shi et al. 2009). In contrast to the structure of the same compound with additional water molecules of hydration (Shi et al. 2009), the dihedral angles of the pyrazole units with respect to the central phenyl group are 76.9 (1)° and 74.5 (1)°, respectively. The hydrated compound further forms a two-dimensional supramolecular network by the hydrogen bond interactions including the water molecules.

Refinement
H atoms were placed in calculated positions, with C-H = 0.93 Å or C-H = 0.97 Å and refined with a riding model, with U iso (H) = 1.2U eq (C). Restraints (DELU) were applied to the U ij parameters of atoms C3 and C4. Fig. 1. The molecular structure of (I), showing displacement ellipsoids at the 30% probability level for non-hydrogen atoms.