4-Phenylpiperazin-1-ium dihydrogen phosphate

The title compound, C10H15N2 +·H2PO4 −, is built up from 4-phenylpiperazin-1-ium cations and dihydrogen phosphate anions. The interconnection between two adjacent anions is assured by two strong O—H⋯O hydrogen bonds, which lead to the formation of infinite wave-like chains which spread along the a axis. The organic cations connect these chains via N—H⋯O hydrogen bonds. The crystal cohesion and stability are ensured by electrostatic and van der Waals interactions which, together with N—H⋯O and O—H⋯O hydrogen bonds, build up a two-dimensional network.

The title compound, C 10 H 15 N 2 + ÁH 2 PO 4 À , is built up from 4phenylpiperazin-1-ium cations and dihydrogen phosphate anions. The interconnection between two adjacent anions is assured by two strong O-HÁ Á ÁO hydrogen bonds, which lead to the formation of infinite wave-like chains which spread along the a axis. The organic cations connect these chains via N-HÁ Á ÁO hydrogen bonds. The crystal cohesion and stability are ensured by electrostatic and van der Waals interactions which, together with N-HÁ Á ÁO and O-HÁ Á ÁO hydrogen bonds, build up a two-dimensional network.
In this work, we report the preparation and the structural investigation of the noncentrosymmetric, (C 10 H 15 N 2 )H 2 PO 4 , (I). This compound is built up from the H 2 PO 4 anion and the organic 4-phenylpiperazin-1-ium cation ( (Ferraris, et al., 1984). Nevertheless, the calculated average values of the distortion indices (Baur, 1974 (Blessing, 1986) to form infinite waved chains which spread along the a axis.
The protonation of the phenylpiperazine can be due to the higher basicity and less constraint on this hydrogen. The piperazinium ring has a chair conformation, the most stable chemical conformation, with bond angles of around 109 °. The The aromatic rings are planar with an average deviation of 0.000343 Å show no significant deviation from those obtained in other 4-phenylpiperazin-1-ium salts such as [C 10 H 15 N 2 ]HgCl 3 (Zouari, et al., 1995) and [C 10 H 16 N 2 ] 2 ZnCl 4 (Ben Gharbia, et al., 2005). The phenylpiperazinium cations are organized in opposite direction along the b axis between the inorganic layers. Furthermore, the inorganic anion chains screen the interaction between the organic cations and probably lead to a non-centrosymmetric atomic arrangement. Therefore, the title compound could be an interesting material in the non-linear optics.
supplementary materials sup-2 The interplanar distance between nearby phenyl rings is in the vicinity of 4.870 Å, which is significantly longer than 3.80 Å for the π-π interaction (Janiak, 2000). The organic cations are linked onto the anionic chains, by forming H-bonds with the oxygen atoms with N-H···O distances in the range 2.675 (3) -2.731 (3) Å. These hydrogen bonds contribute to the cohesion and stability of the network of the studied crystal structure.

Experimental
Single crystals of the title compound were prepared at room temperature from a mixture of an aqueous solution of phosphoric acid (2 mmol), 1-phenylpiperazine (2 mmol), ethanol (10 ml) and water (10 ml). The resulting solution was stirred during 1 h then evaporated slowly at room temperature for several days until the formation of good quality of prismatic single crystals.

Refinement
All H atoms attached to C atoms and N atom were fixed geometrically and treated as riding with C-H = 0.93 Å (aromatic) or 0.97 Å (methylene) and N-H = 0.90 Å with U iso (H) = 1.2U eq (C or N).
Owing to the low number of Friedel pairs, the standard deviation on the Flack parameter is large, -0.1 (2). However inverting the structure lead to a value of 1.1 (2) and then it was assumed that the correct absolute structure corresponds to the refined model. Fig. 1. An ORTEP view of (I) with the atom-labelling scheme. Displacement ellipsoids are drawn at the 30% probability level. H atoms are represented as small spheres of arbitrary radii.

Special details
Geometry. All esds (except the esd in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell esds are taken into account individually in the estimation of esds in distances, angles and torsion angles; correlations between esds in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell esds is used for estimating esds involving l.s. planes.