organic compounds
4-Acetylpiperazinium picrate
aDepartment of Studies in Chemistry, University of Mysore, Manasagangotri, Mysore 570 006, India, and bDepartment of Chemistry, Keene State College, 229 Main Street, Keene, NH 03435-2001, USA
*Correspondence e-mail: jjasinski@keene.edu
In the title salt, C6H13N2O+·C6H2N3O7− (systematic name: 4-acetylpiperazin-1-ium 2,4,6-trinitrophenolate), the piperazin-1-ium ring has a slightly distorted chair conformation. In the picrate anion, the mean planes of the two o-NO2 and p-NO2 groups are twisted with respect to the benzene ring by 15.0 (2), 68.9 (4) and 4.4 (3)°, respectively. In the crystal, N—H⋯O hydrogen bonds are observed, linking the ions into an infinite chain along [010]. In addition, weak cation–anion C—H⋯O intermolecular interactions and a weak π–π stacking interaction between the benzene rings of the anions, with an inter-centroid distance of 3.771 (8) Å, help to stabilize the crystal packing, giving an overall sheet structure lying parallel to (100). Disorder was modelled for one of the O atoms in one of the o-NO2 groups over two sites with an occupancy ratio of 0.57 (6):0.43 (6).
CCDC reference: 1004370
Related literature
Piperazines and substituted piperazines are important pharmacophores that can be found in many biologically active compounds across a number of different therapeutic areas, see: Berkheij (2005); Choudhary et al. (2006); Kharb et al. (2012); Upadhayaya et al. (2004). For picric acid salts, see: Hundal et al. (1997); Szumna et al. (2000); Colquhoun et al. (1986). For related structures, see: Kavitha et al. (2013, 2014); Loughlin et al. (2003); Wang & Jia (2008); Song et al. (2012). For puckering parameters, see Cremer & Pople (1975). For standard bond lengths, see: Allen et al. (1987).
Experimental
Crystal data
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Data collection: CrysAlis PRO (Agilent, 2014); cell CrysAlis PRO; data reduction: CrysAlis PRO; program(s) used to solve structure: SUPERFLIP (Palatinus & Chapuis, 2007); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: OLEX2 (Dolomanov et al., 2009); software used to prepare material for publication: OLEX2.
Supporting information
CCDC reference: 1004370
10.1107/S1600536814011726/zs2300sup1.cif
contains datablock I. DOI:Structure factors: contains datablock I. DOI: 10.1107/S1600536814011726/zs2300Isup2.hkl
Supporting information file. DOI: 10.1107/S1600536814011726/zs2300Isup3.cml
Picric acid (1.14 g, 0.005 mol) was dissolved in methanol and acetyl piperazine (0.63 ml, 0.005 mol) was added to it with stirring. A yellow precipitate was obtained instantaneously. The precipitate was recrystallized from ethanol by slow evaporation (m.p.: 443–448 K).
All of the H atoms were placed in their calculated positions and then refined using the riding model with atom—H lengths of 0.93 Å(CH); 0.97 Å (CH2); 0.96 Å (CH3) or 0.97 Å (NH). Isotropic displacement parameters for these atoms were set to 1.2 (CH, CH2, NH) or 1.5 (CH3) times Ueq of the parent atom. The methyl group was refined as a rotating group. Disorder was modelled for O2B in one of the o-NO2 groups over two sites with an occupancy ratio of 0.57 (6):0.43 (6). The incorrect orthorhombic β = 90.000 (4)°, which prompted the checkCIF/PLATON B-ALERT (SYMMS 02).
was transformed into the correct monoclinic P21/n cell havingData collection: CrysAlis PRO (Agilent, 2014); cell
CrysAlis PRO (Agilent, 2014); data reduction: CrysAlis PRO (Agilent, 2014); program(s) used to solve structure: SUPERFLIP (Palatinus & Chapuis, 2007); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: OLEX2 (Dolomanov et al., 2009); software used to prepare material for publication: OLEX2 (Dolomanov et al., 2009).Fig. 1. ORTEP drawing of the title compound showing the labeling scheme with 30% probability displacement ellipsoids. | |
Fig. 2. Molecular packing viewed along the a axis. Dashed lines indicate N—H···O intermolecular hydrogen bonds forming infinite one-dimensional chains along [0 1 0] and further supported by weak C—H···O intermolecular interactions. H atoms not involved in hydrogen bonding have been removed for clarity. The disordered component of the C2 o-NO2 group is also omitted. |
C6H13N2O+·C6H2N3O7− | Dx = 1.521 Mg m−3 |
Mr = 357.29 | Melting point = 443–448 K |
Monoclinic, P21/n | Cu Kα radiation, λ = 1.54184 Å |
a = 6.6843 (7) Å | Cell parameters from 4582 reflections |
b = 11.5971 (12) Å | θ = 4.4–71.6° |
c = 20.131 (2) Å | µ = 1.12 mm−1 |
β = 90.000 (4)° | T = 173 K |
V = 1560.5 (3) Å3 | Block, yellow |
Z = 4 | 0.32 × 0.28 × 0.06 mm |
F(000) = 744 |
Agilent Eos Gemini diffractometer | 2993 independent reflections |
Radiation source: Enhance (Cu) X-ray Source | 2690 reflections with I > 2σ(I) |
Detector resolution: 16.0416 pixels mm-1 | Rint = 0.036 |
ω scans | θmax = 72.0°, θmin = 4.4° |
Absorption correction: multi-scan (CrysAlis PRO; Agilent, 2014) | h = −8→7 |
Tmin = 0.631, Tmax = 1.000 | k = −14→11 |
9739 measured reflections | l = −24→24 |
Refinement on F2 | Hydrogen site location: inferred from neighbouring sites |
Least-squares matrix: full | H-atom parameters constrained |
R[F2 > 2σ(F2)] = 0.045 | w = 1/[σ2(Fo2) + (0.0624P)2 + 0.6066P] where P = (Fo2 + 2Fc2)/3 |
wR(F2) = 0.126 | (Δ/σ)max < 0.001 |
S = 1.10 | Δρmax = 0.27 e Å−3 |
2993 reflections | Δρmin = −0.20 e Å−3 |
238 parameters | Extinction correction: SHELXL97 (Sheldrick, 2008), Fc*=kFc[1+0.001xFc2λ3/sin(2θ)]-1/4 |
0 restraints | Extinction coefficient: 0.0018 (3) |
Primary atom site location: structure-invariant direct methods |
C6H13N2O+·C6H2N3O7− | V = 1560.5 (3) Å3 |
Mr = 357.29 | Z = 4 |
Monoclinic, P21/n | Cu Kα radiation |
a = 6.6843 (7) Å | µ = 1.12 mm−1 |
b = 11.5971 (12) Å | T = 173 K |
c = 20.131 (2) Å | 0.32 × 0.28 × 0.06 mm |
β = 90.000 (4)° |
Agilent Eos Gemini diffractometer | 2993 independent reflections |
Absorption correction: multi-scan (CrysAlis PRO; Agilent, 2014) | 2690 reflections with I > 2σ(I) |
Tmin = 0.631, Tmax = 1.000 | Rint = 0.036 |
9739 measured reflections |
R[F2 > 2σ(F2)] = 0.045 | 0 restraints |
wR(F2) = 0.126 | H-atom parameters constrained |
S = 1.10 | Δρmax = 0.27 e Å−3 |
2993 reflections | Δρmin = −0.20 e Å−3 |
238 parameters |
Experimental. Absorption correction: CrysAlis PRO (Agilent, 2014), Version 1.171.37.31 (release 14-01-2014 CrysAlis171 .NET) (compiled Jan 14 2014,18:38:05) Empirical absorption correction using spherical harmonics, implemented in SCALE3 ABSPACK scaling algorithm. |
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. |
x | y | z | Uiso*/Ueq | Occ. (<1) | |
O1B | 0.10430 (19) | 0.26818 (11) | 0.61927 (6) | 0.0352 (3) | |
O2B | 0.175 (7) | 0.1019 (8) | 0.7106 (4) | 0.076 (5) | 0.57 (6) |
O2BA | 0.082 (4) | 0.0947 (14) | 0.7071 (7) | 0.051 (4) | 0.43 (6) |
O3B | 0.1631 (3) | −0.07329 (14) | 0.67738 (7) | 0.0541 (4) | |
O4B | 0.3371 (2) | −0.17212 (11) | 0.45759 (7) | 0.0395 (3) | |
O5B | 0.3065 (2) | −0.04833 (12) | 0.37818 (6) | 0.0434 (3) | |
O6B | −0.0003 (2) | 0.34623 (15) | 0.45462 (9) | 0.0573 (4) | |
O7B | 0.2665 (3) | 0.39977 (12) | 0.50421 (8) | 0.0551 (4) | |
N1B | 0.1575 (2) | 0.02945 (14) | 0.66573 (7) | 0.0378 (4) | |
N2B | 0.3023 (2) | −0.07436 (12) | 0.43751 (7) | 0.0291 (3) | |
N3B | 0.1445 (2) | 0.32723 (12) | 0.48878 (7) | 0.0304 (3) | |
C1B | 0.1524 (2) | 0.18809 (14) | 0.58083 (8) | 0.0255 (3) | |
C2B | 0.1827 (2) | 0.06833 (15) | 0.59752 (8) | 0.0274 (4) | |
C3B | 0.2322 (2) | −0.01538 (14) | 0.55123 (8) | 0.0259 (3) | |
H3B | 0.2513 | −0.0913 | 0.5646 | 0.031* | |
C4B | 0.2531 (2) | 0.01431 (14) | 0.48536 (8) | 0.0247 (3) | |
C5B | 0.2228 (2) | 0.12757 (14) | 0.46350 (7) | 0.0249 (3) | |
H5B | 0.2332 | 0.1469 | 0.4188 | 0.030* | |
C6B | 0.1776 (2) | 0.20831 (13) | 0.51029 (8) | 0.0244 (3) | |
O1A | 0.31825 (19) | 0.29011 (10) | 0.33233 (6) | 0.0341 (3) | |
N1A | 0.3133 (2) | 0.48149 (12) | 0.34934 (7) | 0.0290 (3) | |
N2A | 0.1899 (2) | 0.69006 (13) | 0.28906 (7) | 0.0359 (4) | |
H2AA | 0.1923 | 0.7422 | 0.2514 | 0.043* | |
H2AB | 0.1046 | 0.7237 | 0.3229 | 0.043* | |
C1A | 0.4034 (2) | 0.37845 (14) | 0.35166 (8) | 0.0282 (4) | |
C2A | 0.1095 (3) | 0.49259 (15) | 0.32500 (9) | 0.0328 (4) | |
H2AC | 0.0231 | 0.5196 | 0.3605 | 0.039* | |
H2AD | 0.0609 | 0.4180 | 0.3103 | 0.039* | |
C3A | 0.1047 (3) | 0.57715 (17) | 0.26784 (9) | 0.0389 (4) | |
H3AA | 0.1816 | 0.5468 | 0.2309 | 0.047* | |
H3AB | −0.0322 | 0.5878 | 0.2531 | 0.047* | |
C4A | 0.3952 (3) | 0.67764 (15) | 0.31576 (9) | 0.0365 (4) | |
H4AA | 0.4425 | 0.7516 | 0.3318 | 0.044* | |
H4AB | 0.4845 | 0.6520 | 0.2808 | 0.044* | |
C5A | 0.3959 (3) | 0.59116 (15) | 0.37192 (9) | 0.0361 (4) | |
H5AA | 0.5318 | 0.5797 | 0.3875 | 0.043* | |
H5AB | 0.3168 | 0.6204 | 0.4086 | 0.043* | |
C6A | 0.6101 (3) | 0.37046 (19) | 0.37903 (12) | 0.0475 (5) | |
H6AA | 0.6105 | 0.3967 | 0.4242 | 0.071* | |
H6AB | 0.6984 | 0.4177 | 0.3531 | 0.071* | |
H6AC | 0.6545 | 0.2918 | 0.3774 | 0.071* |
U11 | U22 | U33 | U12 | U13 | U23 | |
O1B | 0.0435 (7) | 0.0337 (7) | 0.0286 (6) | 0.0049 (5) | 0.0062 (5) | −0.0059 (5) |
O2B | 0.143 (15) | 0.062 (3) | 0.0223 (16) | −0.009 (4) | −0.002 (4) | −0.0016 (14) |
O2BA | 0.089 (9) | 0.044 (4) | 0.021 (3) | 0.014 (3) | 0.014 (3) | 0.002 (2) |
O3B | 0.0824 (11) | 0.0453 (9) | 0.0347 (7) | 0.0073 (7) | 0.0086 (7) | 0.0161 (6) |
O4B | 0.0513 (8) | 0.0266 (6) | 0.0406 (7) | 0.0050 (5) | 0.0031 (6) | −0.0035 (5) |
O5B | 0.0643 (9) | 0.0419 (7) | 0.0241 (6) | 0.0098 (6) | 0.0067 (6) | −0.0033 (5) |
O6B | 0.0440 (8) | 0.0534 (9) | 0.0744 (11) | 0.0097 (7) | −0.0153 (7) | 0.0236 (8) |
O7B | 0.0842 (11) | 0.0311 (7) | 0.0501 (9) | −0.0127 (7) | −0.0205 (8) | 0.0036 (6) |
N1B | 0.0489 (9) | 0.0413 (9) | 0.0232 (7) | 0.0041 (7) | 0.0007 (6) | 0.0058 (6) |
N2B | 0.0293 (7) | 0.0285 (7) | 0.0295 (7) | 0.0008 (5) | 0.0022 (5) | −0.0038 (6) |
N3B | 0.0381 (8) | 0.0290 (7) | 0.0240 (7) | 0.0052 (6) | 0.0020 (6) | 0.0007 (5) |
C1B | 0.0222 (7) | 0.0325 (8) | 0.0218 (7) | 0.0007 (6) | −0.0001 (5) | −0.0021 (6) |
C2B | 0.0287 (8) | 0.0327 (9) | 0.0206 (8) | −0.0008 (6) | 0.0002 (6) | 0.0029 (6) |
C3B | 0.0238 (7) | 0.0260 (8) | 0.0280 (8) | 0.0007 (6) | −0.0008 (6) | 0.0035 (6) |
C4B | 0.0213 (7) | 0.0276 (8) | 0.0252 (8) | 0.0005 (6) | 0.0013 (6) | −0.0022 (6) |
C5B | 0.0248 (7) | 0.0295 (8) | 0.0206 (7) | 0.0000 (6) | −0.0001 (5) | 0.0014 (6) |
C6B | 0.0229 (7) | 0.0257 (8) | 0.0244 (8) | 0.0014 (6) | −0.0007 (5) | 0.0016 (6) |
O1A | 0.0473 (7) | 0.0235 (6) | 0.0315 (6) | −0.0022 (5) | 0.0039 (5) | −0.0024 (5) |
N1A | 0.0326 (7) | 0.0235 (7) | 0.0308 (7) | −0.0001 (5) | −0.0057 (6) | −0.0032 (5) |
N2A | 0.0523 (9) | 0.0291 (7) | 0.0263 (7) | 0.0109 (6) | 0.0108 (6) | 0.0039 (6) |
C1A | 0.0353 (9) | 0.0263 (8) | 0.0229 (7) | 0.0008 (6) | 0.0029 (6) | 0.0005 (6) |
C2A | 0.0310 (8) | 0.0300 (8) | 0.0375 (9) | 0.0006 (6) | −0.0050 (7) | −0.0014 (7) |
C3A | 0.0435 (10) | 0.0408 (10) | 0.0323 (9) | 0.0081 (8) | −0.0078 (7) | −0.0026 (7) |
C4A | 0.0464 (10) | 0.0240 (8) | 0.0391 (10) | −0.0024 (7) | 0.0085 (8) | −0.0068 (7) |
C5A | 0.0462 (10) | 0.0276 (9) | 0.0345 (9) | −0.0033 (7) | −0.0084 (7) | −0.0076 (7) |
C6A | 0.0388 (11) | 0.0455 (11) | 0.0582 (13) | 0.0096 (8) | −0.0082 (9) | −0.0002 (9) |
O1B—C1B | 1.251 (2) | N1A—C2A | 1.453 (2) |
O2B—N1B | 1.239 (7) | N1A—C5A | 1.459 (2) |
O2BA—N1B | 1.231 (10) | N2A—H2AA | 0.9700 |
O3B—N1B | 1.215 (2) | N2A—H2AB | 0.9700 |
O4B—N2B | 1.2260 (19) | N2A—C3A | 1.490 (2) |
O5B—N2B | 1.232 (2) | N2A—C4A | 1.481 (3) |
O6B—N3B | 1.208 (2) | C1A—C6A | 1.490 (3) |
O7B—N3B | 1.212 (2) | C2A—H2AC | 0.9700 |
N1B—C2B | 1.455 (2) | C2A—H2AD | 0.9700 |
N2B—C4B | 1.447 (2) | C2A—C3A | 1.512 (3) |
N3B—C6B | 1.462 (2) | C3A—H3AA | 0.9700 |
C1B—C2B | 1.443 (2) | C3A—H3AB | 0.9700 |
C1B—C6B | 1.449 (2) | C4A—H4AA | 0.9700 |
C2B—C3B | 1.386 (2) | C4A—H4AB | 0.9700 |
C3B—H3B | 0.9300 | C4A—C5A | 1.511 (3) |
C3B—C4B | 1.377 (2) | C5A—H5AA | 0.9700 |
C4B—C5B | 1.400 (2) | C5A—H5AB | 0.9700 |
C5B—H5B | 0.9300 | C6A—H6AA | 0.9600 |
C5B—C6B | 1.362 (2) | C6A—H6AB | 0.9600 |
O1A—C1A | 1.235 (2) | C6A—H6AC | 0.9600 |
N1A—C1A | 1.339 (2) | ||
O2B—N1B—C2B | 117.9 (5) | C4A—N2A—H2AB | 109.2 |
O2BA—N1B—C2B | 119.6 (4) | C4A—N2A—C3A | 111.88 (13) |
O3B—N1B—O2B | 121.4 (4) | O1A—C1A—N1A | 121.49 (15) |
O3B—N1B—O2BA | 119.0 (6) | O1A—C1A—C6A | 119.48 (16) |
O3B—N1B—C2B | 118.85 (15) | N1A—C1A—C6A | 119.03 (16) |
O4B—N2B—O5B | 122.81 (14) | N1A—C2A—H2AC | 109.8 |
O4B—N2B—C4B | 118.74 (14) | N1A—C2A—H2AD | 109.8 |
O5B—N2B—C4B | 118.45 (14) | N1A—C2A—C3A | 109.51 (15) |
O6B—N3B—O7B | 123.95 (16) | H2AC—C2A—H2AD | 108.2 |
O6B—N3B—C6B | 117.50 (15) | C3A—C2A—H2AC | 109.8 |
O7B—N3B—C6B | 118.50 (14) | C3A—C2A—H2AD | 109.8 |
O1B—C1B—C2B | 127.34 (15) | N2A—C3A—C2A | 110.09 (15) |
O1B—C1B—C6B | 121.06 (15) | N2A—C3A—H3AA | 109.6 |
C2B—C1B—C6B | 111.57 (14) | N2A—C3A—H3AB | 109.6 |
C1B—C2B—N1B | 120.12 (14) | C2A—C3A—H3AA | 109.6 |
C3B—C2B—N1B | 116.43 (15) | C2A—C3A—H3AB | 109.6 |
C3B—C2B—C1B | 123.44 (14) | H3AA—C3A—H3AB | 108.2 |
C2B—C3B—H3B | 120.1 | N2A—C4A—H4AA | 109.7 |
C4B—C3B—C2B | 119.78 (15) | N2A—C4A—H4AB | 109.7 |
C4B—C3B—H3B | 120.1 | N2A—C4A—C5A | 109.82 (15) |
C3B—C4B—N2B | 119.11 (14) | H4AA—C4A—H4AB | 108.2 |
C3B—C4B—C5B | 121.50 (14) | C5A—C4A—H4AA | 109.7 |
C5B—C4B—N2B | 119.36 (14) | C5A—C4A—H4AB | 109.7 |
C4B—C5B—H5B | 121.3 | N1A—C5A—C4A | 110.13 (14) |
C6B—C5B—C4B | 117.37 (14) | N1A—C5A—H5AA | 109.6 |
C6B—C5B—H5B | 121.3 | N1A—C5A—H5AB | 109.6 |
C1B—C6B—N3B | 115.17 (13) | C4A—C5A—H5AA | 109.6 |
C5B—C6B—N3B | 118.50 (14) | C4A—C5A—H5AB | 109.6 |
C5B—C6B—C1B | 126.31 (15) | H5AA—C5A—H5AB | 108.1 |
C1A—N1A—C2A | 120.82 (14) | C1A—C6A—H6AA | 109.5 |
C1A—N1A—C5A | 126.65 (14) | C1A—C6A—H6AB | 109.5 |
C2A—N1A—C5A | 112.49 (14) | C1A—C6A—H6AC | 109.5 |
H2AA—N2A—H2AB | 107.9 | H6AA—C6A—H6AB | 109.5 |
C3A—N2A—H2AA | 109.2 | H6AA—C6A—H6AC | 109.5 |
C3A—N2A—H2AB | 109.2 | H6AB—C6A—H6AC | 109.5 |
C4A—N2A—H2AA | 109.2 | ||
O1B—C1B—C2B—N1B | 0.0 (3) | C2B—C1B—C6B—N3B | 178.55 (13) |
O1B—C1B—C2B—C3B | 178.68 (15) | C2B—C1B—C6B—C5B | 0.4 (2) |
O1B—C1B—C6B—N3B | 0.5 (2) | C2B—C3B—C4B—N2B | −179.20 (13) |
O1B—C1B—C6B—C5B | −177.66 (15) | C2B—C3B—C4B—C5B | −0.9 (2) |
O2B—N1B—C2B—C1B | −23 (2) | C3B—C4B—C5B—C6B | 1.9 (2) |
O2B—N1B—C2B—C3B | 158 (2) | C4B—C5B—C6B—N3B | −179.80 (13) |
O2BA—N1B—C2B—C1B | 10.6 (19) | C4B—C5B—C6B—C1B | −1.7 (2) |
O2BA—N1B—C2B—C3B | −168.2 (18) | C6B—C1B—C2B—N1B | −177.95 (14) |
O3B—N1B—C2B—C1B | 172.35 (17) | C6B—C1B—C2B—C3B | 0.8 (2) |
O3B—N1B—C2B—C3B | −6.5 (2) | N1A—C2A—C3A—N2A | −56.25 (19) |
O4B—N2B—C4B—C3B | −4.8 (2) | N2A—C4A—C5A—N1A | 55.87 (19) |
O4B—N2B—C4B—C5B | 176.84 (14) | C1A—N1A—C2A—C3A | −123.25 (17) |
O5B—N2B—C4B—C3B | 174.87 (15) | C1A—N1A—C5A—C4A | 123.37 (18) |
O5B—N2B—C4B—C5B | −3.5 (2) | C2A—N1A—C1A—O1A | 1.2 (2) |
O6B—N3B—C6B—C1B | −111.79 (18) | C2A—N1A—C1A—C6A | −178.04 (17) |
O6B—N3B—C6B—C5B | 66.5 (2) | C2A—N1A—C5A—C4A | −59.09 (19) |
O7B—N3B—C6B—C1B | 70.6 (2) | C3A—N2A—C4A—C5A | −55.55 (18) |
O7B—N3B—C6B—C5B | −111.05 (18) | C4A—N2A—C3A—C2A | 56.01 (19) |
N1B—C2B—C3B—C4B | 178.21 (14) | C5A—N1A—C1A—O1A | 178.54 (16) |
N2B—C4B—C5B—C6B | −179.75 (13) | C5A—N1A—C1A—C6A | −0.7 (3) |
C1B—C2B—C3B—C4B | −0.5 (2) | C5A—N1A—C2A—C3A | 59.05 (19) |
D—H···A | D—H | H···A | D···A | D—H···A |
N2A—H2AA···O1Ai | 0.97 | 1.78 | 2.7057 (19) | 159 |
N2A—H2AB···O1Bii | 0.97 | 1.82 | 2.7401 (19) | 157 |
C3A—H3AA···O5Bi | 0.97 | 2.46 | 3.333 (2) | 150 |
C3A—H3AB···O3Biii | 0.97 | 2.55 | 3.469 (3) | 158 |
C5A—H5AA···O7Biv | 0.97 | 2.57 | 3.365 (2) | 139 |
C5B—H5B···O1A | 0.93 | 2.47 | 3.307 (2) | 149 |
C5A—H5AB···O4Bv | 0.97 | 2.60 | 3.266 (2) | 126 |
Symmetry codes: (i) −x+1/2, y+1/2, −z+1/2; (ii) −x, −y+1, −z+1; (iii) x−1/2, −y+1/2, z−1/2; (iv) −x+1, −y+1, −z+1; (v) x, y+1, z. |
D—H···A | D—H | H···A | D···A | D—H···A |
N2A—H2AA···O1Ai | 0.97 | 1.78 | 2.7057 (19) | 159 |
N2A—H2AB···O1Bii | 0.97 | 1.82 | 2.7401 (19) | 157 |
C3A—H3AA···O5Bi | 0.97 | 2.46 | 3.333 (2) | 150 |
C3A—H3AB···O3Biii | 0.97 | 2.55 | 3.469 (3) | 158 |
C5A—H5AA···O7Biv | 0.97 | 2.57 | 3.365 (2) | 139 |
C5B—H5B···O1A | 0.93 | 2.47 | 3.307 (2) | 149 |
Symmetry codes: (i) −x+1/2, y+1/2, −z+1/2; (ii) −x, −y+1, −z+1; (iii) x−1/2, −y+1/2, z−1/2; (iv) −x+1, −y+1, −z+1. |
Acknowledgements
CNK thanks the University of Mysore for research facilities and also grateful to the Principal, Maharani's Science College for Women, Mysore, for giving permission to undertake research. JPJ acknowledges the NSF–MRI program (grant No. CHE-1039027) for funds to purchase the X-ray diffractometer.
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This is an open-access article distributed under the terms of the Creative Commons Attribution (CC-BY) Licence, which permits unrestricted use, distribution, and reproduction in any medium, provided the original authors and source are cited.
Piperazines and substituted piperazines are important pharmacophores that can be found in many biologically active compounds across a number of different therapeutic areas (Berkheij, 2005) such as antifungal (Upadhayaya et al., 2004), anti-bacterial, anti-malarial and anti-psychotic agents (Choudhary et al., 2006). A valuable insight into recent advances on antimicrobial activity of piperazine derivatives has been reported (Kharb et al., 2012). Also picric acid forms salts which exhibit electrostatic forces, multiple hydrogen bonds (Hundal et al., 1997; Szumna et al., 2000) and π–π stacking interactions (Colquhoun et al., 1986), which improve the quality of the crystalline materials. The supra-molecular structure of molecular adducts of picric acid and piperazine have been reported (Wang & Jia, 2008). The crystal structures of some related compounds, viz., 1-[4-(4-hydroxyphenyl)piperazin-1-yl]ethanone (Kavitha et al., 2013), 3-(Z)-isobutylidene-1-acetylpiperazine-2,5-dione (Loughlin et al. , 2003), piperazine-1,4-diium picrate-piperazine (Wang & Jia, 2008), cinnarizinium picrate (Song et al., 2012) and 1-piperonylpiperazinium picrate (Kavitha et al., 2014) have been reported. In view of the importance of the title compound, C6H13N2O+. C6H2N3O7-, this paper reports its crystal structure.
The title salt crystallizes with one piperazinium cation (A) and a picrate anion (B) in the asymmetric unit (Fig. 1). In the cation, the piperazine ring is in a slightly distorted chair conformation (puckering parameters Q, θ, and ϕ = 0.569 (2)Å, 178.3 (5)° and 197 (9)°, respectively (Cremer & Pople, 1975). In the picrate anion, the mean planes of the two o-NO2 groups and the p-NO2 group are twisted with respect to the phenyl ring plane by 15.0 (2)°, 68.9 (4)° and 4.4 (3)°, respectively. Bond lengths are in normal ranges (Allen et al., 1987). Intermolecular N—H···O hydrogen bonds are observed (Table 1) linking the anions with the cations and other anions forming an infinite one-dimensional chain along [010] (Fig. 2). In addition, weak cation-anion intermolecular C—H···O interactions and a weak π–π stacking interaction between the anionic phenyl rings [inter-centroid distance = 3.771 (8) Å] stabilize the crystal packing and generate a overall two-dimensional sheet structure lying parallel to (100). Disorder was modelled for the O2B oxygen atom in one of the o-NO2 groups over two sites with an occupancy ratio of 0.57 (6):0.43 (6).