organic compounds
1-(2-Azaniumylethyl)piperazine-1,4-diium trinitrate
aDepartment of Chemistry, University of Pretoria, Pretoria, 0002, South Africa
*Correspondence e-mail: melanie.rademeyer@up.ac.za
In the title salt, C6H18N33+·3NO3−, the piperazine ring adopts a chair conformation and the ethylammonium group is equatorial relative to the piperazine ring, and in an all-trans conformation. In the crystal, strong charge-assisted N—H⋯O hydrogen bonds link the piperazinediium trications and the nitrate anions into a three-dimensional network
Related literature
The structure of a related salt, bis(1-(2-ammoniumethyl)piperazinium) cyclohexaphosphate hexahydrate, has been reported (Charfi & Jouini, 1996).
Experimental
Crystal data
|
Refinement
|
Data collection: CrysAlis CCD (Oxford Diffraction, 2006); cell CrysAlis RED (Oxford Diffraction, 2006); data reduction: CrysAlis RED; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: Mercury (Macrae et al., 2008); software used to prepare material for publication: PLATON (Spek, 2009) and WinGX (Farrugia, 1999).
Supporting information
https://doi.org/10.1107/S1600536811047507/bt5713sup1.cif
contains datablocks I, global. DOI:Structure factors: contains datablock I. DOI: https://doi.org/10.1107/S1600536811047507/bt5713Isup2.hkl
Supporting information file. DOI: https://doi.org/10.1107/S1600536811047507/bt5713Isup3.cml
1-(2-Ammoniumethyl)piperazinium trinitrate was prepared by the dropwise addition of excess concentrated nitric acid (3.0 ml, 0.047 mol, 70%, Saarchem) to a solution of 1-(2-aminoethyl)piperazine (1.5 ml, 0.011 mol 99%, Aldrich) in 40 ml chloroform (99%, Saarchem). The resulting precipitate was filtered, dried in air and re-crystallized from distilled water. Colourless crystals formed on evaporation, open to the air, at room temperature.
All H atoms were refined using a riding model, with C—H distances of 0.97 Å and N—H distances of 0.89 Å, and Uiso(H) = 1.5Ueq(C) or 1.2Ueq(C) or 1.2Ueq(N). The highest residual peak (0.24eÅ-3) is 0.83 Å from atom O1.
In the field of crystal engineering, an understanding of the role of the anion geometry on the molecular packing and non-covalent interactions in salt crystal structures is central to the area of molecular recognition. The current structure was determined as part of a wider study that considers this role of anion geometry on a crystal structure.
The molecular geometry and labelling scheme of 1-(2-ammoniumethyl)piperazinium) trinitrate, I, is illustrated in Fig. 1. In this structure, the
consists of one 1-(2-ammoniumethyl)piperazinium cation and three isolated, trigonal planar nitrate anions, with four asymmetric units in the In the cation the piperazine ring adopts the chair conformation, and the ethylammonium group is equatorial relative to the piperazine ring, and in the all-trans conformation.Fig. 2 shows the molecular packing of I, viewed down the a-axis, with double rows of cations alternating in orientation along the c-axis. Each cation is hydrogen bonded to six different surrounding nitrate anions, and strong N—H+···-O—N hydrogen bonds link the cations and the anions. The ammonium group on the cation froms one conventional and two bifurcated hydrogen bonds to three different nitrate anions, while the –NH2+ group is involved in two bifurcated hydrogen bonds to two nitrate anions, and the –NH+ group forms one bifurcated hydrogen bond to one nitrate anion. Hydrogen bonding interactions are listed in Table 1, and the resulting, complex, three-dimensional hydrogen bonding network is shown in Fig. 3.
The structure of a related salt, bis(1-(2-ammoniumethyl)piperazinium) cyclohexaphosphate hexahydrate, has been reported (Charfi & Jouini, 1996).
Data collection: CrysAlis CCD (Oxford Diffraction, 2006); cell
CrysAlis RED (Oxford Diffraction, 2006); data reduction: CrysAlis RED (Oxford Diffraction, 2006); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: Mercury (Macrae et al., 2008); software used to prepare material for publication: PLATON (Spek, 2009) and WinGX (Farrugia, 1999).Fig. 1. The asymmetric unit of I, showing the atomic numbering scheme. Displacement ellipsoids are shown at the 50% probability level and H atoms are shown as small spheres of arbitrary radii. | |
Fig. 2. Packing diagram of I viewed down the a-axis. | |
Fig. 3. Hydrogen bonding network in I. |
C6H18N33+·3NO3− | F(000) = 672 |
Mr = 318.26 | Dx = 1.552 Mg m−3 |
Monoclinic, P21/c | Mo Kα radiation, λ = 0.71073 Å |
Hall symbol: -P 2ybc | Cell parameters from 5277 reflections |
a = 7.7946 (6) Å | θ = 3.7–32.0° |
b = 8.9320 (6) Å | µ = 0.14 mm−1 |
c = 19.6910 (13) Å | T = 293 K |
β = 96.635 (6)° | Block, colourless |
V = 1361.73 (17) Å3 | 0.35 × 0.30 × 0.20 mm |
Z = 4 |
Oxford Xcalibur2 diffractometer | 4319 independent reflections |
Radiation source: fine-focus sealed tube | 2517 reflections with I > 2σ(I) |
Graphite monochromator | Rint = 0.022 |
ω–2θ scans | θmax = 32.0°, θmin = 3.7° |
Absorption correction: multi-scan (CrysAlis RED; Oxford Diffraction, 2006) | h = −11→6 |
Tmin = 0.966, Tmax = 1.043 | k = −12→12 |
13603 measured reflections | l = −28→29 |
Refinement on F2 | Secondary atom site location: difference Fourier map |
Least-squares matrix: full | Hydrogen site location: inferred from neighbouring sites |
R[F2 > 2σ(F2)] = 0.042 | H-atom parameters constrained |
wR(F2) = 0.129 | w = 1/[σ2(Fo2) + (0.074P)2] where P = (Fo2 + 2Fc2)/3 |
S = 1.01 | (Δ/σ)max = 0.001 |
4319 reflections | Δρmax = 0.24 e Å−3 |
192 parameters | Δρmin = −0.21 e Å−3 |
0 restraints | Extinction correction: SHELXL97 (Sheldrick, 2008), Fc*=kFc[1+0.001xFc2λ3/sin(2θ)]-1/4 |
Primary atom site location: structure-invariant direct methods | Extinction coefficient: 0.033 (3) |
C6H18N33+·3NO3− | V = 1361.73 (17) Å3 |
Mr = 318.26 | Z = 4 |
Monoclinic, P21/c | Mo Kα radiation |
a = 7.7946 (6) Å | µ = 0.14 mm−1 |
b = 8.9320 (6) Å | T = 293 K |
c = 19.6910 (13) Å | 0.35 × 0.30 × 0.20 mm |
β = 96.635 (6)° |
Oxford Xcalibur2 diffractometer | 4319 independent reflections |
Absorption correction: multi-scan (CrysAlis RED; Oxford Diffraction, 2006) | 2517 reflections with I > 2σ(I) |
Tmin = 0.966, Tmax = 1.043 | Rint = 0.022 |
13603 measured reflections |
R[F2 > 2σ(F2)] = 0.042 | 0 restraints |
wR(F2) = 0.129 | H-atom parameters constrained |
S = 1.01 | Δρmax = 0.24 e Å−3 |
4319 reflections | Δρmin = −0.21 e Å−3 |
192 parameters |
Experimental. CrysAlis RED (Oxford Diffraction, 2006) Version 1.171.29.9 Empirical absorption correction using spherical harmonics, implemented in SCALE3 ABSPACK scaling algorithm. |
Geometry. All e.s.d.'s (except the e.s.d. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell e.s.d.'s are taken into account individually in the estimation of e.s.d.'s in distances, angles and torsion angles; correlations between e.s.d.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell e.s.d.'s is used for estimating e.s.d.'s involving l.s. planes. |
Refinement. Refinement of F2 against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F2, conventional R-factors R are based on F, with F set to zero for negative F2. The threshold expression of F2 > σ(F2) is used only for calculating R-factors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F2 are statistically about twice as large as those based on F, and R- factors based on ALL data will be even larger. |
x | y | z | Uiso*/Ueq | ||
O8 | −0.12932 (14) | 0.16141 (11) | 0.10385 (6) | 0.0633 (3) | |
O9 | −0.14426 (14) | 0.36595 (11) | 0.16044 (5) | 0.0567 (3) | |
N5 | 0.25593 (12) | 0.88408 (10) | 0.10913 (5) | 0.0323 (2) | |
H5 | 0.3465 | 0.8265 | 0.0997 | 0.039* | |
N4 | 0.02701 (14) | 0.65031 (12) | 0.14525 (6) | 0.0448 (3) | |
H4A | 0.0034 | 0.5530 | 0.1515 | 0.054* | |
H4B | −0.0651 | 0.7043 | 0.1544 | 0.054* | |
N6 | 0.49105 (14) | 1.25521 (12) | 0.11758 (5) | 0.0432 (3) | |
H7A | 0.4563 | 1.2789 | 0.0743 | 0.065* | |
H7B | 0.6012 | 1.2814 | 0.1278 | 0.065* | |
H7C | 0.4265 | 1.3035 | 0.1449 | 0.065* | |
C4 | 0.22499 (17) | 0.85655 (14) | 0.18187 (6) | 0.0387 (3) | |
H4C | 0.1312 | 0.9198 | 0.1932 | 0.046* | |
H4D | 0.3278 | 0.8830 | 0.2120 | 0.046* | |
C1 | 0.09846 (17) | 0.83708 (15) | 0.06264 (6) | 0.0428 (3) | |
H1A | 0.0008 | 0.8981 | 0.0718 | 0.051* | |
H1B | 0.1182 | 0.8531 | 0.0154 | 0.051* | |
C5 | 0.29617 (16) | 1.04353 (13) | 0.09492 (6) | 0.0398 (3) | |
H5A | 0.2098 | 1.1071 | 0.1120 | 0.048* | |
H5B | 0.2890 | 1.0580 | 0.0458 | 0.048* | |
C3 | 0.18042 (18) | 0.69465 (15) | 0.19308 (7) | 0.0445 (3) | |
H3A | 0.2779 | 0.6317 | 0.1856 | 0.053* | |
H3B | 0.1561 | 0.6806 | 0.2399 | 0.053* | |
C2 | 0.05773 (17) | 0.67486 (15) | 0.07315 (6) | 0.0445 (3) | |
H2A | −0.0442 | 0.6465 | 0.0429 | 0.053* | |
H2B | 0.1533 | 0.6131 | 0.0624 | 0.053* | |
C6 | 0.47308 (16) | 1.09143 (14) | 0.12711 (7) | 0.0442 (3) | |
H6A | 0.4868 | 1.0674 | 0.1755 | 0.053* | |
H6B | 0.5616 | 1.0388 | 0.1058 | 0.053* | |
O7 | 0.05818 (13) | 0.33529 (11) | 0.09607 (6) | 0.0573 (3) | |
N3 | −0.07066 (14) | 0.28710 (12) | 0.12031 (5) | 0.0409 (3) | |
N2 | 0.26751 (13) | 0.30391 (12) | 0.26544 (5) | 0.0410 (3) | |
O4 | 0.37816 (13) | 0.37345 (12) | 0.23659 (5) | 0.0573 (3) | |
O5 | 0.21779 (16) | 0.35660 (13) | 0.31806 (7) | 0.0743 (4) | |
O6 | 0.20595 (15) | 0.18569 (12) | 0.24225 (5) | 0.0625 (3) | |
N1 | 0.43842 (14) | 0.14691 (14) | 0.44408 (6) | 0.0486 (3) | |
O1 | 0.49718 (18) | 0.26837 (13) | 0.46985 (6) | 0.0719 (3) | |
O2 | 0.49348 (16) | 0.10390 (15) | 0.39153 (6) | 0.0766 (4) | |
O3 | 0.33557 (14) | 0.07557 (17) | 0.47326 (8) | 0.0917 (5) |
U11 | U22 | U33 | U12 | U13 | U23 | |
O8 | 0.0685 (7) | 0.0463 (6) | 0.0767 (7) | −0.0175 (5) | 0.0153 (6) | −0.0120 (5) |
O9 | 0.0719 (7) | 0.0479 (6) | 0.0544 (6) | 0.0080 (5) | 0.0245 (5) | −0.0032 (4) |
N5 | 0.0334 (5) | 0.0314 (5) | 0.0327 (5) | 0.0000 (4) | 0.0066 (4) | 0.0000 (4) |
N4 | 0.0540 (6) | 0.0339 (5) | 0.0495 (6) | −0.0102 (5) | 0.0187 (5) | −0.0043 (4) |
N6 | 0.0467 (6) | 0.0392 (6) | 0.0450 (6) | −0.0089 (4) | 0.0112 (5) | −0.0005 (4) |
C4 | 0.0464 (7) | 0.0388 (6) | 0.0310 (6) | −0.0053 (5) | 0.0050 (5) | −0.0014 (4) |
C1 | 0.0463 (7) | 0.0442 (7) | 0.0363 (6) | −0.0068 (5) | −0.0017 (5) | 0.0017 (5) |
C5 | 0.0439 (6) | 0.0331 (6) | 0.0420 (7) | −0.0028 (5) | 0.0035 (5) | 0.0057 (5) |
C3 | 0.0580 (8) | 0.0391 (7) | 0.0377 (7) | 0.0003 (6) | 0.0109 (6) | 0.0048 (5) |
C2 | 0.0487 (7) | 0.0451 (7) | 0.0401 (7) | −0.0117 (6) | 0.0066 (6) | −0.0092 (5) |
C6 | 0.0389 (6) | 0.0374 (7) | 0.0565 (8) | −0.0016 (5) | 0.0059 (6) | 0.0043 (6) |
O7 | 0.0538 (6) | 0.0439 (5) | 0.0785 (7) | −0.0018 (4) | 0.0255 (5) | 0.0070 (5) |
N3 | 0.0442 (6) | 0.0383 (6) | 0.0402 (6) | 0.0027 (5) | 0.0050 (4) | 0.0053 (4) |
N2 | 0.0399 (5) | 0.0419 (6) | 0.0414 (6) | −0.0011 (4) | 0.0059 (5) | −0.0061 (4) |
O4 | 0.0572 (6) | 0.0620 (7) | 0.0559 (6) | −0.0157 (5) | 0.0205 (5) | −0.0081 (5) |
O5 | 0.0777 (7) | 0.0731 (8) | 0.0802 (8) | −0.0278 (6) | 0.0434 (6) | −0.0406 (6) |
O6 | 0.0849 (8) | 0.0474 (6) | 0.0571 (6) | −0.0186 (5) | 0.0162 (6) | −0.0165 (5) |
N1 | 0.0379 (5) | 0.0574 (7) | 0.0515 (7) | 0.0028 (5) | 0.0087 (5) | 0.0133 (5) |
O1 | 0.1058 (9) | 0.0543 (7) | 0.0572 (7) | −0.0008 (6) | 0.0166 (6) | −0.0007 (5) |
O2 | 0.0825 (8) | 0.0947 (10) | 0.0554 (7) | −0.0013 (7) | 0.0206 (6) | −0.0126 (6) |
O3 | 0.0447 (6) | 0.1131 (11) | 0.1208 (11) | −0.0054 (6) | 0.0251 (7) | 0.0587 (9) |
O8—N3 | 1.2411 (14) | C1—H1A | 0.9700 |
O9—N3 | 1.2468 (14) | C1—H1B | 0.9700 |
N5—C5 | 1.4918 (15) | C5—C6 | 1.5114 (18) |
N5—C4 | 1.5000 (15) | C5—H5A | 0.9700 |
N5—C1 | 1.5037 (15) | C5—H5B | 0.9700 |
N5—H5 | 0.9100 | C3—H3A | 0.9700 |
N4—C2 | 1.4831 (16) | C3—H3B | 0.9700 |
N4—C3 | 1.4878 (17) | C2—H2A | 0.9700 |
N4—H4A | 0.9000 | C2—H2B | 0.9700 |
N4—H4B | 0.9000 | C6—H6A | 0.9700 |
N6—C6 | 1.4836 (16) | C6—H6B | 0.9700 |
N6—H7A | 0.8900 | O7—N3 | 1.2379 (14) |
N6—H7B | 0.8900 | N2—O6 | 1.2261 (14) |
N6—H7C | 0.8900 | N2—O5 | 1.2402 (14) |
C4—C3 | 1.5094 (17) | N2—O4 | 1.2512 (14) |
C4—H4C | 0.9700 | N1—O3 | 1.2187 (15) |
C4—H4D | 0.9700 | N1—O2 | 1.2269 (16) |
C1—C2 | 1.5028 (19) | N1—O1 | 1.2611 (16) |
C5—N5—C4 | 113.34 (9) | C6—C5—H5A | 109.0 |
C5—N5—C1 | 109.08 (9) | N5—C5—H5B | 109.0 |
C4—N5—C1 | 109.00 (9) | C6—C5—H5B | 109.0 |
C5—N5—H5 | 108.4 | H5A—C5—H5B | 107.8 |
C4—N5—H5 | 108.4 | N4—C3—C4 | 110.13 (10) |
C1—N5—H5 | 108.4 | N4—C3—H3A | 109.6 |
C2—N4—C3 | 111.09 (9) | C4—C3—H3A | 109.6 |
C2—N4—H4A | 109.4 | N4—C3—H3B | 109.6 |
C3—N4—H4A | 109.4 | C4—C3—H3B | 109.6 |
C2—N4—H4B | 109.4 | H3A—C3—H3B | 108.1 |
C3—N4—H4B | 109.4 | N4—C2—C1 | 109.54 (10) |
H4A—N4—H4B | 108.0 | N4—C2—H2A | 109.8 |
C6—N6—H7A | 109.5 | C1—C2—H2A | 109.8 |
C6—N6—H7B | 109.5 | N4—C2—H2B | 109.8 |
H7A—N6—H7B | 109.5 | C1—C2—H2B | 109.8 |
C6—N6—H7C | 109.5 | H2A—C2—H2B | 108.2 |
H7A—N6—H7C | 109.5 | N6—C6—C5 | 108.72 (10) |
H7B—N6—H7C | 109.5 | N6—C6—H6A | 109.9 |
N5—C4—C3 | 111.21 (10) | C5—C6—H6A | 109.9 |
N5—C4—H4C | 109.4 | N6—C6—H6B | 109.9 |
C3—C4—H4C | 109.4 | C5—C6—H6B | 109.9 |
N5—C4—H4D | 109.4 | H6A—C6—H6B | 108.3 |
C3—C4—H4D | 109.4 | O7—N3—O8 | 120.31 (11) |
H4C—C4—H4D | 108.0 | O7—N3—O9 | 120.08 (11) |
C2—C1—N5 | 110.85 (10) | O8—N3—O9 | 119.59 (11) |
C2—C1—H1A | 109.5 | O6—N2—O5 | 119.43 (11) |
N5—C1—H1A | 109.5 | O6—N2—O4 | 121.27 (11) |
C2—C1—H1B | 109.5 | O5—N2—O4 | 119.29 (11) |
N5—C1—H1B | 109.5 | O3—N1—O2 | 123.17 (15) |
H1A—C1—H1B | 108.1 | O3—N1—O1 | 119.22 (14) |
N5—C5—C6 | 113.14 (10) | O2—N1—O1 | 117.55 (12) |
N5—C5—H5A | 109.0 | ||
C5—N5—C4—C3 | 178.55 (10) | C2—N4—C3—C4 | 57.49 (14) |
C1—N5—C4—C3 | 56.88 (13) | N5—C4—C3—N4 | −56.80 (14) |
C5—N5—C1—C2 | 177.55 (10) | C3—N4—C2—C1 | −58.69 (14) |
C4—N5—C1—C2 | −58.23 (13) | N5—C1—C2—N4 | 59.29 (14) |
C4—N5—C5—C6 | 71.34 (13) | N5—C5—C6—N6 | −172.78 (10) |
C1—N5—C5—C6 | −167.04 (11) |
D—H···A | D—H | H···A | D···A | D—H···A |
N5—H5···O1i | 0.91 | 2.00 | 2.8074 (16) | 146 |
N5—H5···O2i | 0.91 | 2.34 | 3.1755 (17) | 152 |
N4—H4A···O9 | 0.90 | 2.05 | 2.9008 (15) | 158 |
N4—H4A···O7 | 0.90 | 2.29 | 2.9947 (15) | 135 |
N4—H4B···O5ii | 0.90 | 1.93 | 2.8065 (16) | 165 |
N4—H4B···O6ii | 0.90 | 2.43 | 3.0387 (15) | 125 |
N6—H7A···O1iii | 0.89 | 2.16 | 2.9224 (15) | 144 |
N6—H7A···O3iii | 0.89 | 2.47 | 3.322 (2) | 161 |
N6—H7B···O9iv | 0.89 | 2.15 | 3.0360 (15) | 173 |
N6—H7B···O8iv | 0.89 | 2.45 | 3.1171 (16) | 132 |
N6—H7C···O4v | 0.89 | 1.99 | 2.8033 (14) | 152 |
Symmetry codes: (i) −x+1, y+1/2, −z+1/2; (ii) −x, y+1/2, −z+1/2; (iii) x, −y+3/2, z−1/2; (iv) x+1, y+1, z; (v) x, y+1, z. |
Experimental details
Crystal data | |
Chemical formula | C6H18N33+·3NO3− |
Mr | 318.26 |
Crystal system, space group | Monoclinic, P21/c |
Temperature (K) | 293 |
a, b, c (Å) | 7.7946 (6), 8.9320 (6), 19.6910 (13) |
β (°) | 96.635 (6) |
V (Å3) | 1361.73 (17) |
Z | 4 |
Radiation type | Mo Kα |
µ (mm−1) | 0.14 |
Crystal size (mm) | 0.35 × 0.30 × 0.20 |
Data collection | |
Diffractometer | Oxford Xcalibur2 |
Absorption correction | Multi-scan (CrysAlis RED; Oxford Diffraction, 2006) |
Tmin, Tmax | 0.966, 1.043 |
No. of measured, independent and observed [I > 2σ(I)] reflections | 13603, 4319, 2517 |
Rint | 0.022 |
(sin θ/λ)max (Å−1) | 0.746 |
Refinement | |
R[F2 > 2σ(F2)], wR(F2), S | 0.042, 0.129, 1.01 |
No. of reflections | 4319 |
No. of parameters | 192 |
H-atom treatment | H-atom parameters constrained |
Δρmax, Δρmin (e Å−3) | 0.24, −0.21 |
Computer programs: CrysAlis CCD (Oxford Diffraction, 2006), CrysAlis RED (Oxford Diffraction, 2006), SHELXS97 (Sheldrick, 2008), SHELXL97 (Sheldrick, 2008), Mercury (Macrae et al., 2008), PLATON (Spek, 2009) and WinGX (Farrugia, 1999).
D—H···A | D—H | H···A | D···A | D—H···A |
N5—H5···O1i | 0.91 | 2.00 | 2.8074 (16) | 146.4 |
N5—H5···O2i | 0.91 | 2.34 | 3.1755 (17) | 152.1 |
N4—H4A···O9 | 0.90 | 2.05 | 2.9008 (15) | 157.8 |
N4—H4A···O7 | 0.90 | 2.29 | 2.9947 (15) | 134.5 |
N4—H4B···O5ii | 0.90 | 1.93 | 2.8065 (16) | 165.4 |
N4—H4B···O6ii | 0.90 | 2.43 | 3.0387 (15) | 125.4 |
N6—H7A···O1iii | 0.89 | 2.16 | 2.9224 (15) | 143.5 |
N6—H7A···O3iii | 0.89 | 2.47 | 3.322 (2) | 160.5 |
N6—H7B···O9iv | 0.89 | 2.15 | 3.0360 (15) | 172.9 |
N6—H7B···O8iv | 0.89 | 2.45 | 3.1171 (16) | 131.8 |
N6—H7C···O4v | 0.89 | 1.99 | 2.8033 (14) | 151.9 |
Symmetry codes: (i) −x+1, y+1/2, −z+1/2; (ii) −x, y+1/2, −z+1/2; (iii) x, −y+3/2, z−1/2; (iv) x+1, y+1, z; (v) x, y+1, z. |
Acknowledgements
Funding received for this work from the University of Pretoria, the University of KwaZulu-Natal and the National Research Foundation (GUN: 2054350) is acknowledged.
References
Charfi, M. & Jouini, A. (1996). J. Solid State. Chem. 127, 9–18. CSD CrossRef CAS Web of Science Google Scholar
Farrugia, L. J. (1999). J. Appl. Cryst. 32, 837–838. CrossRef CAS IUCr Journals Google Scholar
Macrae, C. F., Bruno, I. J., Chisholm, J. A., Edgington, P. R., McCabe, P., Pidcock, E., Rodriguez-Monge, L., Taylor, R., van de Streek, J. & Wood, P. A. (2008). J. Appl. Cryst. 41, 466–470. Web of Science CSD CrossRef CAS IUCr Journals Google Scholar
Oxford Diffraction (2006). CrysAlis CCD and CrysAlis RED. Oxford Diffraction Ltd, Abingdon, England. Google Scholar
Sheldrick, G. M. (2008). Acta Cryst. A64, 112–122. Web of Science CrossRef CAS IUCr Journals Google Scholar
Spek, A. L. (2009). Acta Cryst. D65, 148–155. Web of Science CrossRef CAS IUCr Journals Google Scholar
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.
In the field of crystal engineering, an understanding of the role of the anion geometry on the molecular packing and non-covalent interactions in salt crystal structures is central to the area of molecular recognition. The current structure was determined as part of a wider study that considers this role of anion geometry on a crystal structure.
The molecular geometry and labelling scheme of 1-(2-ammoniumethyl)piperazinium) trinitrate, I, is illustrated in Fig. 1. In this structure, the asymmetric unit consists of one 1-(2-ammoniumethyl)piperazinium cation and three isolated, trigonal planar nitrate anions, with four asymmetric units in the unit cell. In the cation the piperazine ring adopts the chair conformation, and the ethylammonium group is equatorial relative to the piperazine ring, and in the all-trans conformation.
Fig. 2 shows the molecular packing of I, viewed down the a-axis, with double rows of cations alternating in orientation along the c-axis. Each cation is hydrogen bonded to six different surrounding nitrate anions, and strong N—H+···-O—N hydrogen bonds link the cations and the anions. The ammonium group on the cation froms one conventional and two bifurcated hydrogen bonds to three different nitrate anions, while the –NH2+ group is involved in two bifurcated hydrogen bonds to two nitrate anions, and the –NH+ group forms one bifurcated hydrogen bond to one nitrate anion. Hydrogen bonding interactions are listed in Table 1, and the resulting, complex, three-dimensional hydrogen bonding network is shown in Fig. 3.