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ISSN: 2056-9890

2-Amino-3-nitro­pyridinium perchlorate

aLaboratoire de Chimie des Matériaux, Faculté des Sciences de Bizerte, 7021 Zarzouna Bizerte, Tunisia, and bChemistry Department, Faculty of Science, King Saud University, PO Box 2455, Riyadh 11451, Saudi Arabia
*Correspondence e-mail: toumiakriche@yahoo.fr

(Received 14 December 2009; accepted 5 January 2010; online 9 January 2010)

The title compound, C5H6N3O2+·ClO4, is comprised of discrete perchlorate anions and 2-amino-3-nitro­pyridinium cations. The anion has a typical tetra­hedral geometry while the cation presents a nearly planar [maximum deviation = 0.007 (8) Å] pyridinium ring. Undulating [C5H6N3O2+]n chains extending along the c-axis direction are linked via N—H⋯O hydrogen bonds. The cations are further connected to the anions by N—H⋯O hydrogen bonds and weak C—H⋯O inter­actions, leading to the formation of a three-dimensional network.

Related literature

For related structures, see: Akriche & Rzaigui (2000[Akriche, S. & Rzaigui, M. (2000). Z. Kristallogr. New Cryst. Struct. 215, 617-618.], 2009a[Akriche, S. & Rzaigui, M. (2009a). Acta Cryst. E65, m123.],b[Akriche, S. & Rzaigui, M. (2009b). Acta Cryst. E65, o1648.],c[Akriche, S. & Rzaigui, M. (2009c). Acta Cryst. E65, o793.]); Nicoud et al. (1997[Nicoud, J. F., Masse, R., Bourgogne, C. & Evans, C. (1997). J. Mater. Chem. 7, 35-39.]). For details of hydrogen bonding, see: Steiner & Saenger (1994[Steiner, T. & Saenger, W. (1994). Acta Cryst. B50, 348-357.]). For bond lengths in related structures, see: Aakeröy et al. (1998[Aakeröy, C. B., Beatty, A. M., Nieuwenhuyzen, M. & Zou, M. (1998). J. Mater. Chem. pp. 1385-1389.]); Messai et al. (2009[Messai, A., Direm, A., Benali-Cherif, N., Luneau, D. & Jeanneau, E. (2009). Acta Cryst. E65, o460.]).

[Scheme 1]

Experimental

Crystal data
  • C5H6N3O2+·ClO4

  • Mr = 239.58

  • Monoclinic, P 21 /c

  • a = 5.888 (2) Å

  • b = 18.342 (6) Å

  • c = 9.170 (4) Å

  • β = 116.61 (3)°

  • V = 885.3 (6) Å3

  • Z = 4

  • Mo Kα radiation

  • μ = 0.45 mm−1

  • T = 293 K

  • 0.29 × 0.25 × 0.21 mm

Data collection
  • Enraf–Nonius TurboCAD-4 diffractometer

  • Absorption correction: multi-scan (Blessing, 1995[Blessing, R. H. (1995). Acta Cryst. A51, 33-38.]) Tmin = 0.725, Tmax = 0.912

  • 3574 measured reflections

  • 2130 independent reflections

  • 1109 reflections with I > 2σ(I)

  • Rint = 0.046

  • 2 standard reflections every 120 min intensity decay: 1%

Refinement
  • R[F2 > 2σ(F2)] = 0.062

  • wR(F2) = 0.189

  • S = 1.00

  • 2130 reflections

  • 136 parameters

  • 66 restraints

  • H-atom parameters constrained

  • Δρmax = 0.52 e Å−3

  • Δρmin = −0.30 e Å−3

Table 1
Hydrogen-bond geometry (Å, °)

D—H⋯A D—H H⋯A DA D—H⋯A
N1—H1⋯O1 0.86 2.28 2.927 (5) 133
N1—H1⋯O1i 0.86 2.44 2.969 (5) 121
N2—H2A⋯O2ii 0.86 2.03 2.886 (5) 173
N2—H2B⋯O5 0.86 2.04 2.633 (5) 126
N2—H2B⋯O6iii 0.86 2.32 2.917 (5) 126
C5—H5⋯O3iv 0.93 2.57 3.270 (5) 133
Symmetry codes: (i) -x+1, -y+1, -z+2; (ii) -x+2, -y+1, -z+2; (iii) [x+1, -y+{\script{3\over 2}}, z+{\script{1\over 2}}]; (iv) x-1, y, z.

Data collection: CAD-4 EXPRESS (Enraf–Nonius, 1994[Enraf-Nonius (1994). CAD-4 EXPRESS. Enraf-Nonius, Delft, The Netherlands.]); cell refinement: CAD-4 EXPRESS; data reduction: XCAD4 (Harms & Wocadlo, 1995[Harms, K. & Wocadlo, S. (1995). XCAD4. University of Marburg, Germany.]); program(s) used to solve structure: SHELXS86 (Sheldrick, 2008[Sheldrick, G. M. (2008). Acta Cryst. A64, 112-122.]); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008[Sheldrick, G. M. (2008). Acta Cryst. A64, 112-122.]); molecular graphics: ORTEP-3 for Windows (Farrugia, 1997[Farrugia, L. J. (1997). J. Appl. Cryst. 30, 565.]) and DIAMOND (Brandenburg & Putz, 2005[Brandenburg, K. & Putz, H. (2005). DIAMOND. Crystal impact GbR, Bonn, Germany.]); software used to prepare material for publication: WinGX (Farrugia, 1999[Farrugia, L. J. (1999). J. Appl. Cryst. 32, 837-838.]).

Supporting information


Comment top

Salts of 2-amino-3-nitropyridine attracted more attention as non linear optical (NLO) materials after discovering the promising properties of 2-amino-3-nitropyridinium chloride (Nicoud et al.,1997). With the purpose of obtaining non-centrosymmetric crystals of 2-amino-3-nitropyridine salts, its interaction with various acids has been studied and we have elaborated a serie of new materials with this organic molecule (Akriche & Rzaigui, 2000; Akriche & Rzaigui, 2009a; 2009b; 2009c). In this paper, we describe the crystal structure of the title compound (I).

The asymmetric unit of (I) is composed of a perchlorate anion and a 2-amino-3-nitropyridinium (2 A3NP) cation (Fig. 1). The anions are surrounded by two cations via hydrogen bonds which play an important role in stabilizing the crystal structure (Fig. 2). In the crystal structure, one can distinguish the ondulated chains of the cations extending along the c axis. The adjacent cations are joined by the N2—H2B···O6 (Table 1) hydrogen bond with N···O distance of 2.917 (5) Å. The cations are also connected to the chlorate anions by hydrogen bonds, of the type N—H···O with N···O distances in the range 2.886 (5) - 2.969 (5) Å, and weak C5—H5···O3 interaction with C5···O3 separation 3.270 (5) Å (Fig. 2, Table 1). The C—H···O bonds have already been evidenced by several authors in molecular crystals (Steiner et al., 1994).

The anion displays a typical tetrahedral geometry around Cl atom and the Cl···O distances compare well with previously reported values (Messai et al., 2009). The Cl—O bond distances and O—Cl—O bond angles (Table: Geometric parameters) confirm a tetrahedral conformation, similar to other perchlorates quoted above.

The pyridinium ring of the cation is nearly planar, with maximum deviation from planarity being 0.007 (8) Å for C1 atom. The diedral angle between the planes of the NO2 group and the pyridinium ring is 9.7 (2) ° indicating a deviation of the NO2 group from being co-planar with the ring since its oxygen atoms are involved in various types of inter- and intramolecular hydrogen bonds. Moreover, the C—NH2 (1.313 (5) Å) and C—NO2 (1.448 (5) Å) distances in the 2 A3NP cation are respectively shortened and lengthened with respect to the C—NH2 (1.337 (4) Å) and C—NO2 (1.429 (4) Å) observed in the crystal structure of 2-amino-3-nitropyridine (Aakeröy et al., 1998). All the 2-amino-3-nitropyridinium cations hosted in various organic or inorganic matrices show the same changes in C—NH2 and C—NO2 distances, revealing a weak increase of π bond character in C—NH2 and a decrease in C—NO2. The bond lengths of cation in (I) are normal and comparable with the corresponding values observed in the related structure (Akriche & Rzaigui, 2000; Akriche & Rzaigui, 2009a; 2009b, 2009c).

Related literature top

For related structures, see: Akriche & Rzaigui (2000, 2009a,b,c); Nicoud et al. (1997). For hydrogen bonds, see: Steiner & Saenger (1994). For bond lengths in related structures, see: Aakeröy et al. (1998); Messai et al. (2009).

Experimental top

2-Amino-3-nitropyridine (4 mmol, 354 mg) was dissolved in a solution of perchloride acid (4 mmol in 20 ml water). The mixture was stirred for about 30 min at 333 K and evaporated in the air giving colorless block crystals of the title compound suitable for X-ray analysis.

Refinement top

H atoms were treated as riding, with C—H = 0.93 A ° and N—H = 0.86 A ° and with Uiso(H) = 1.2Ueq(C or N). The atoms of the chlorate ion were refined using isotropic Uij restraints.

Structure description top

Salts of 2-amino-3-nitropyridine attracted more attention as non linear optical (NLO) materials after discovering the promising properties of 2-amino-3-nitropyridinium chloride (Nicoud et al.,1997). With the purpose of obtaining non-centrosymmetric crystals of 2-amino-3-nitropyridine salts, its interaction with various acids has been studied and we have elaborated a serie of new materials with this organic molecule (Akriche & Rzaigui, 2000; Akriche & Rzaigui, 2009a; 2009b; 2009c). In this paper, we describe the crystal structure of the title compound (I).

The asymmetric unit of (I) is composed of a perchlorate anion and a 2-amino-3-nitropyridinium (2 A3NP) cation (Fig. 1). The anions are surrounded by two cations via hydrogen bonds which play an important role in stabilizing the crystal structure (Fig. 2). In the crystal structure, one can distinguish the ondulated chains of the cations extending along the c axis. The adjacent cations are joined by the N2—H2B···O6 (Table 1) hydrogen bond with N···O distance of 2.917 (5) Å. The cations are also connected to the chlorate anions by hydrogen bonds, of the type N—H···O with N···O distances in the range 2.886 (5) - 2.969 (5) Å, and weak C5—H5···O3 interaction with C5···O3 separation 3.270 (5) Å (Fig. 2, Table 1). The C—H···O bonds have already been evidenced by several authors in molecular crystals (Steiner et al., 1994).

The anion displays a typical tetrahedral geometry around Cl atom and the Cl···O distances compare well with previously reported values (Messai et al., 2009). The Cl—O bond distances and O—Cl—O bond angles (Table: Geometric parameters) confirm a tetrahedral conformation, similar to other perchlorates quoted above.

The pyridinium ring of the cation is nearly planar, with maximum deviation from planarity being 0.007 (8) Å for C1 atom. The diedral angle between the planes of the NO2 group and the pyridinium ring is 9.7 (2) ° indicating a deviation of the NO2 group from being co-planar with the ring since its oxygen atoms are involved in various types of inter- and intramolecular hydrogen bonds. Moreover, the C—NH2 (1.313 (5) Å) and C—NO2 (1.448 (5) Å) distances in the 2 A3NP cation are respectively shortened and lengthened with respect to the C—NH2 (1.337 (4) Å) and C—NO2 (1.429 (4) Å) observed in the crystal structure of 2-amino-3-nitropyridine (Aakeröy et al., 1998). All the 2-amino-3-nitropyridinium cations hosted in various organic or inorganic matrices show the same changes in C—NH2 and C—NO2 distances, revealing a weak increase of π bond character in C—NH2 and a decrease in C—NO2. The bond lengths of cation in (I) are normal and comparable with the corresponding values observed in the related structure (Akriche & Rzaigui, 2000; Akriche & Rzaigui, 2009a; 2009b, 2009c).

For related structures, see: Akriche & Rzaigui (2000, 2009a,b,c); Nicoud et al. (1997). For hydrogen bonds, see: Steiner & Saenger (1994). For bond lengths in related structures, see: Aakeröy et al. (1998); Messai et al. (2009).

Computing details top

Data collection: CAD-4 EXPRESS (Enraf–Nonius, 1994); cell refinement: CAD-4 EXPRESS (Enraf–Nonius, 1994); data reduction: XCAD4 (Harms & Wocadlo, 1995); program(s) used to solve structure: SHELXS86 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: ORTEP-3 for Windows (Farrugia, 1997) and DIAMOND (Brandenburg & Putz, 2005); software used to prepare material for publication: WinGX (Farrugia, 1999).

Figures top
[Figure 1] 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 by spheres of arbitrary radii. Hydrogen bonds are represented as dashed lines.
[Figure 2] Fig. 2. Projection of (I) down the a axis. The H-atoms not involved in H-bonding are omitted.
2-Amino-3-nitropyridinium perchlorate top
Crystal data top
C5H6N3O2+·ClO4F(000) = 488
Mr = 239.58Dx = 1.797 Mg m3
Monoclinic, P21/cMo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ybcCell parameters from 25 reflections
a = 5.888 (2) Åθ = 9–11°
b = 18.342 (6) ŵ = 0.45 mm1
c = 9.170 (4) ÅT = 293 K
β = 116.61 (3)°Prism, colorless
V = 885.3 (6) Å30.29 × 0.25 × 0.21 mm
Z = 4
Data collection top
Enraf–Nonius TurboCAD-4
diffractometer
1109 reflections with I > 2σ(I)
Radiation source: fine-focus sealed tubeRint = 0.046
Graphite monochromatorθmax = 28.0°, θmin = 2.2°
Non–profiled ω scansh = 77
Absorption correction: multi-scan
(Blessing, 1995)
k = 240
Tmin = 0.725, Tmax = 1.101l = 1112
3574 measured reflections2 standard reflections every 120 min
2130 independent reflections intensity decay: 1%
Refinement top
Refinement on F2Primary atom site location: structure-invariant direct methods
Least-squares matrix: fullSecondary atom site location: difference Fourier map
R[F2 > 2σ(F2)] = 0.062Hydrogen site location: inferred from neighbouring sites
wR(F2) = 0.189H-atom parameters constrained
S = 1.00 w = 1/[σ2(Fo2) + (0.096P)2]
where P = (Fo2 + 2Fc2)/3
2130 reflections(Δ/σ)max < 0.001
136 parametersΔρmax = 0.52 e Å3
66 restraintsΔρmin = 0.30 e Å3
Crystal data top
C5H6N3O2+·ClO4V = 885.3 (6) Å3
Mr = 239.58Z = 4
Monoclinic, P21/cMo Kα radiation
a = 5.888 (2) ŵ = 0.45 mm1
b = 18.342 (6) ÅT = 293 K
c = 9.170 (4) Å0.29 × 0.25 × 0.21 mm
β = 116.61 (3)°
Data collection top
Enraf–Nonius TurboCAD-4
diffractometer
1109 reflections with I > 2σ(I)
Absorption correction: multi-scan
(Blessing, 1995)
Rint = 0.046
Tmin = 0.725, Tmax = 1.1012 standard reflections every 120 min
3574 measured reflections intensity decay: 1%
2130 independent reflections
Refinement top
R[F2 > 2σ(F2)] = 0.06266 restraints
wR(F2) = 0.189H-atom parameters constrained
S = 1.00Δρmax = 0.52 e Å3
2130 reflectionsΔρmin = 0.30 e Å3
136 parameters
Special details top

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.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top
xyzUiso*/Ueq
O10.6409 (9)0.45343 (19)0.9234 (4)0.0967 (12)
O20.9810 (6)0.4058 (2)0.8940 (5)0.1130 (15)
O30.6657 (6)0.46634 (17)0.6814 (4)0.0750 (9)
O40.5876 (7)0.35339 (19)0.7581 (5)0.0970 (12)
N10.3798 (6)0.58877 (17)0.7702 (4)0.0563 (8)
H10.48360.56860.86020.068*
N20.7098 (6)0.6608 (2)0.7939 (4)0.0663 (10)
H2A0.80510.63810.88260.080*
H2B0.77200.69530.75920.080*
N30.3603 (7)0.73452 (18)0.4915 (4)0.0562 (9)
C10.4694 (7)0.6428 (2)0.7117 (4)0.0453 (9)
C20.2906 (7)0.67427 (18)0.5653 (4)0.0419 (8)
C30.0457 (7)0.6493 (2)0.4903 (5)0.0498 (9)
H30.07020.67050.39320.060*
C40.0302 (7)0.5927 (2)0.5582 (5)0.0544 (10)
H40.19570.57500.50770.065*
C50.1418 (9)0.5641 (2)0.6989 (5)0.0591 (11)
H50.09440.52650.74750.071*
O50.5840 (6)0.75060 (17)0.5457 (4)0.0767 (9)
O60.1928 (6)0.76632 (17)0.3776 (4)0.0757 (9)
Cl10.71827 (18)0.41956 (5)0.81544 (11)0.0530 (3)
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
O10.161 (4)0.083 (2)0.076 (2)0.040 (2)0.079 (2)0.0169 (19)
O20.057 (2)0.133 (4)0.119 (3)0.022 (2)0.013 (2)0.029 (3)
O30.090 (2)0.078 (2)0.0663 (19)0.0100 (17)0.0439 (17)0.0197 (16)
O40.116 (3)0.066 (2)0.111 (3)0.024 (2)0.052 (2)0.009 (2)
N10.068 (2)0.0509 (19)0.0523 (19)0.0097 (18)0.0286 (17)0.0124 (16)
N20.048 (2)0.077 (3)0.065 (2)0.0020 (18)0.0174 (17)0.003 (2)
N30.064 (2)0.0459 (19)0.070 (2)0.0006 (18)0.040 (2)0.0018 (17)
C10.052 (2)0.044 (2)0.044 (2)0.0093 (17)0.0256 (18)0.0033 (16)
C20.054 (2)0.0345 (17)0.048 (2)0.0019 (16)0.0320 (18)0.0017 (15)
C30.051 (2)0.052 (2)0.046 (2)0.0064 (18)0.0219 (18)0.0028 (18)
C40.053 (2)0.055 (2)0.062 (3)0.0066 (19)0.032 (2)0.004 (2)
C50.078 (3)0.049 (2)0.065 (3)0.006 (2)0.045 (2)0.000 (2)
O50.073 (2)0.067 (2)0.103 (2)0.0138 (18)0.0520 (19)0.0072 (18)
O60.085 (2)0.064 (2)0.086 (2)0.0191 (18)0.0458 (19)0.0309 (18)
Cl10.0554 (6)0.0519 (6)0.0498 (6)0.0047 (5)0.0219 (4)0.0041 (5)
Geometric parameters (Å, º) top
O1—Cl11.406 (3)N3—O61.216 (4)
O2—Cl11.406 (3)N3—O51.218 (4)
O3—Cl11.415 (3)N3—C21.448 (5)
O4—Cl11.407 (3)C1—C21.406 (5)
N1—C51.332 (5)C2—C31.369 (5)
N1—C11.343 (5)C3—C41.384 (5)
N1—H10.8600C3—H30.9300
N2—C11.313 (5)C4—C51.339 (6)
N2—H2A0.8600C4—H40.9300
N2—H2B0.8600C5—H50.9300
C5—N1—C1124.8 (3)C2—C3—C4120.3 (4)
C5—N1—H1117.6C2—C3—H3119.8
C1—N1—H1117.6C4—C3—H3119.8
C1—N2—H2A120.0C5—C4—C3118.0 (4)
C1—N2—H2B120.0C5—C4—H4121.0
H2A—N2—H2B120.0C3—C4—H4121.0
O6—N3—O5123.1 (3)N1—C5—C4121.0 (4)
O6—N3—C2118.5 (3)N1—C5—H5119.5
O5—N3—C2118.4 (3)C4—C5—H5119.5
N2—C1—N1118.1 (4)O2—Cl1—O1110.3 (3)
N2—C1—C2126.8 (4)O2—Cl1—O4109.2 (3)
N1—C1—C2115.1 (3)O1—Cl1—O4110.4 (2)
C3—C2—C1120.8 (3)O2—Cl1—O3108.4 (2)
C3—C2—N3118.4 (3)O1—Cl1—O3109.26 (19)
C1—C2—N3120.8 (4)O4—Cl1—O3109.2 (2)
C5—N1—C1—N2179.1 (4)O6—N3—C2—C1170.3 (3)
C5—N1—C1—C20.9 (5)O5—N3—C2—C110.0 (5)
N2—C1—C2—C3178.9 (3)C1—C2—C3—C40.3 (5)
N1—C1—C2—C31.1 (5)N3—C2—C3—C4179.0 (3)
N2—C1—C2—N31.8 (6)C2—C3—C4—C50.7 (6)
N1—C1—C2—N3178.3 (3)C1—N1—C5—C40.1 (6)
O6—N3—C2—C39.0 (5)C3—C4—C5—N10.9 (6)
O5—N3—C2—C3170.7 (3)
Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
N1—H1···O10.862.282.927 (5)133
N1—H1···O1i0.862.442.969 (5)121
N2—H2A···O2ii0.862.032.886 (5)173
N2—H2B···O50.862.042.633 (5)126
N2—H2B···O6iii0.862.322.917 (5)126
C5—H5···O3iv0.932.573.270 (5)133
Symmetry codes: (i) x+1, y+1, z+2; (ii) x+2, y+1, z+2; (iii) x+1, y+3/2, z+1/2; (iv) x1, y, z.

Experimental details

Crystal data
Chemical formulaC5H6N3O2+·ClO4
Mr239.58
Crystal system, space groupMonoclinic, P21/c
Temperature (K)293
a, b, c (Å)5.888 (2), 18.342 (6), 9.170 (4)
β (°) 116.61 (3)
V3)885.3 (6)
Z4
Radiation typeMo Kα
µ (mm1)0.45
Crystal size (mm)0.29 × 0.25 × 0.21
Data collection
DiffractometerEnraf–Nonius TurboCAD-4
Absorption correctionMulti-scan
(Blessing, 1995)
Tmin, Tmax0.725, 1.101
No. of measured, independent and
observed [I > 2σ(I)] reflections
3574, 2130, 1109
Rint0.046
(sin θ/λ)max1)0.660
Refinement
R[F2 > 2σ(F2)], wR(F2), S 0.062, 0.189, 1.00
No. of reflections2130
No. of parameters136
No. of restraints66
H-atom treatmentH-atom parameters constrained
Δρmax, Δρmin (e Å3)0.52, 0.30

Computer programs: CAD-4 EXPRESS (Enraf–Nonius, 1994), XCAD4 (Harms & Wocadlo, 1995), SHELXS86 (Sheldrick, 2008), SHELXL97 (Sheldrick, 2008), ORTEP-3 for Windows (Farrugia, 1997) and DIAMOND (Brandenburg & Putz, 2005), WinGX (Farrugia, 1999).

Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
N1—H1···O10.862.282.927 (5)132.6
N1—H1···O1i0.862.442.969 (5)120.6
N2—H2A···O2ii0.862.032.886 (5)173.1
N2—H2B···O50.862.042.633 (5)125.7
N2—H2B···O6iii0.862.322.917 (5)126.2
C5—H5···O3iv0.932.573.270 (5)132.9
Symmetry codes: (i) x+1, y+1, z+2; (ii) x+2, y+1, z+2; (iii) x+1, y+3/2, z+1/2; (iv) x1, y, z.
 

References

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First citationAkriche, S. & Rzaigui, M. (2009a). Acta Cryst. E65, m123.  Web of Science CSD CrossRef IUCr Journals Google Scholar
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