Three-dimensional network in piper­azine-1,4-diium–picrate–piperazine (1/2/1)

Zhong-Long Wang; Li-Hui Jia

doi:10.1107/S1600536808005710

. 2008 Mar 5;64(Pt 4):o665–o666. doi: 10.1107/S1600536808005710

Three-dimensional network in piperazine-1,4-diium–picrate–piperazine (1/2/1)

Zhong-Long Wang ^a,^*, Li-Hui Jia ^b

PMCID: PMC2960966 PMID: 21202060

Abstract

In the title compound, C₄H₁₂N₂ ²⁺·2C₆H₂N₃O₇ ⁻·C₄H₁₀N₂, the piperazine-1,4-diium cations and piperazine molecules lie on crystallographic inversion centres. In the crystal structure, intermolecular N—H⋯O and N—H⋯N hydrogen bonds link the components to form two-dimensional layers parallel to the (001) plane. These layers are, in turn, connected by weak intermolecular C—H⋯O hydrogen bonds and π–π stacking interactions [centroid–centroid distance between parallel aryl rings = 3.764 (2) Å, interplanar spacing = 3.500 (2) Å and ring offset = 1.387 (2) Å], forming a three-dimensional framework.

Related literature

For related literature, see: Akutagawa et al. (2003 ▶); Anitha et al. (2006a ▶,b ▶); Arnaud et al. (2007 ▶); Colquhoun et al. (1986 ▶); Hundal et al. (1997 ▶); Kavitha et al. (2005 ▶, 2006 ▶); Ma et al. (2005 ▶); Szumna et al. (2000 ▶); Vembu et al. (2003 ▶).

Experimental

Crystal data

C₄H₁₂N₂ ²⁺·2C₆H₂N₃O₇ ⁻·C₄H₁₀N₂
M _r = 630.50
Triclinic,
a = 7.7150 (6) Å
b = 8.1658 (6) Å
c = 11.3024 (8) Å
α = 98.140 (1)°
β = 98.974 (1)°
γ = 109.250 (1)°
V = 649.62 (8) Å³
Z = 1
Mo Kα radiation
μ = 0.14 mm⁻¹
T = 299 (2) K
0.20 × 0.10 × 0.06 mm

Data collection

Bruker SMART APEX CCD area-detector diffractometer
Absorption correction: multi-scan (SADABS; Sheldrick, 1997 ▶) T _min = 0.963, T _max = 0.992
6131 measured reflections
2258 independent reflections
1917 reflections with I > 2σ(I)
R _int = 0.028

Refinement

R[F ² > 2σ(F ²)] = 0.068
wR(F ²) = 0.169
S = 1.13
2258 reflections
208 parameters
H atoms treated by a mixture of independent and constrained refinement
Δρ_max = 0.27 e Å⁻³
Δρ_min = −0.27 e Å⁻³

Data collection: SMART (Bruker, 2001 ▶); cell refinement: SAINT-Plus (Bruker, 2001 ▶); data reduction: SAINT-Plus; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 ▶); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 ▶); molecular graphics: PLATON (Spek, 2003 ▶); software used to prepare material for publication: PLATON.

Supplementary Material

Crystal structure: contains datablocks global, I. DOI: 10.1107/S1600536808005710/lh2598sup1.cif

e-64-0o665-sup1.cif^{(18.1KB, cif)}

Structure factors: contains datablocks I. DOI: 10.1107/S1600536808005710/lh2598Isup2.hkl

e-64-0o665-Isup2.hkl^{(111KB, hkl)}

Additional supplementary materials: crystallographic information; 3D view; checkCIF report

Table 1. Hydrogen-bond geometry (Å, °).

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
N4—H4A⋯O1	0.86 (4)	1.95 (4)	2.745 (4)	153 (4)
N4—H4A⋯O7	0.86 (4)	2.31 (4)	2.870 (5)	123 (3)
N4—H4B⋯N5	0.86 (4)	1.94 (4)	2.799 (4)	176 (4)
N5—H5A⋯O2ⁱ	0.86 (4)	2.41 (4)	3.153 (5)	145 (4)
C2—H2⋯O6ⁱⁱ	0.93	2.47	3.335 (5)	155
C7—H7B⋯O1ⁱⁱⁱ	0.97	2.52	3.211 (5)	128
C8—H8B⋯O1	0.97	2.60	3.267 (5)	127
C8—H8B⋯O2	0.97	2.52	3.458 (5)	162
C9—H9A⋯O5^iv	0.97	2.60	3.272 (5)	127
C10—H10A⋯O4^v	0.97	2.52	3.310 (5)	138

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Symmetry codes: (i) Inline graphic ; (ii) ; (iii) ; (iv) ; (v) .

Acknowledgments

This work received financial support from the Hubei Province Key Fundamental Project.

supplementary crystallographic information

Comment

Studies of picric acid (abbr. PA, pKa = 0.38) have been carried out for many years due to its formation of salts which involve electrostatic forces, multiple hydrogen bond modes (e.g. Hundal et al., 1997; Szumna et al., 2000) and π–π stacking interactions (Colquhoun et al., 1986) which can improve the quality of the crystalline materials. Recently, picrate anion containing molecular adducts have also been reported frequently in order to probe the competition between various intermolecular forces in crystal engineering (Anitha et al., 2006a, 2006b; Vembu et al., 2003; Ma et al., 2005; Akutagawa et al., 2003, Kavitha et al., 2005; Arnaud et al., 2007). As part of our study on molecular adducts involved with PA and piperazine (abbr. PP), we report here the molecular and supra-molecular structure of the title compound (I).

In (I), the asymmetric unit (atoms labelled without lower case suffixes in Fig.1) consists of one picrate anion, half a PA di-cation and half a neutral PA molecule. In the picrate anion, the nitro group at the 4-position is almost coplanar with the phenyl ring with a dihedral angle of only 4.1 (2)°, however, the nitro groups at the 2- and 6-positions are both significantly twisted out of the plane of the benzene ring, with dihedral angles of 45.2 (2)° and 21.7 (2)°, respectively. The rotations of the nitro groups at the 2- and 6- positions means that the picrate anion retains the approximate mirror symmetry which is also observed in the structure of a recently reported analog (Kavitha et al., 2006).

Analysis of the crystal packing of (I) shows that the component ions and molecules are linked into a simple three-dimensional network by a combination of N–H···O (or N), C–H···O hydrogen bonds and π–π stacking interactions which can be analyzed in terms of several substructures. First, by the co-operative hydrogen-bonding actions, i.e. bifurcated N4···O1(O7), bifurcated C8···O1(O2) and C7···O1 (-x, 2 - y, 1 - z) hydrogen bonds, the PA anions, PP di-cations and PP neutral molecules are linked into a one-dimensional tape structure parallel to the [110] direction generated by translation and inversion operations (Fig.2). Secondly, by a combinative actions of N5—H5A···O2 (x, 1 + y, z) and C2—H2···O6 (x, y - 1, z) hydrogen-bonds, the adjacent [110] 1-D tapes are joined together, forming a two-dimensional layer parallel to the (001) plane lying in domain of -0.299 < z < 1.299 (Fig.3). Finally, the neighbouring (001) layers are joined together by means of C9···O5 (-x + 1, -y + 3, -z + 2), C10···O4 (-x + 1, -y + 2, -z + 2) hydrogen bonds and π–π stacking interactions, which form the simple 3-D network. The geometry details of the π–π stacking interactions are as follows. The C1—C6 aryl rings of the anions at (x, y, z) and (1 - x, 2 - y, 2 - z) are strictly parallel, with an inter-planar spacing of 3.500 (2) Å; the ring-centroid separation is 3.764 (2) Å, corresponding to a ring offset of 1.387 (2) Å.

Experimental

All the reagents and solvents were used as obtained without further purification. 1:2 molar amount of anhydrous piperazine (0.2 mmol, 17.2 mg) and picric acid (0.4 mmol, 91.6 mg) were dissolved in 95% methanol (10 ml). The mixture was stirred for half an hour at ambient temperature and then filtered. The resulting yellow solution was kept in air for several days. Plate yellow crystals of (I) suitable for single-crystal X-ray diffraction analysis were grown by slow evaporation of the solution at the bottom of the vessel (yield: 45%, 56.7 mg, based on 2:1 organic salt; melting point: 512–514 K).