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organic compounds\(\def\hfill{\hskip 5em}\def\hfil{\hskip 3em}\def\eqno#1{\hfil {#1}}\)

Journal logoCRYSTALLOGRAPHIC
COMMUNICATIONS
ISSN: 2056-9890
Volume 68| Part 7| July 2012| Pages o2228-o2229
https://doi.org/10.1107/S1600536812028103

Ammonium 4-meth­­oxy­benzene­sulfonate

Sebastián Suarez,a* Fabio Doctorovicha‡ and Ricardo Baggiob

aDepartamento de Química Inorgánica, Analítica y Química, Física/INQUIMAE–CONICET, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Buenos Aires, Argentina, and bGerencia de Investigación y Aplicaciones, Centro Atómico Constituyentes, Comisión Nacional de Energía Atómica, Buenos Aires, Argentina
*Correspondence e-mail: seba@qi.fcen.uba.ar

(Received 14 June 2012; accepted 20 June 2012; online 27 June 2012)

The mol­ecular structure of the title compound, NH4+·C7H7O4S−, is featureless [the methoxy C atom deviating 0.173 (6) Å from the phenyl mean plane] with inter­atomic distances and angles in the expected ranges. The main feature of inter­est is the packing mode. Hydro­philic (SO3 and NH4) and hydro­phobic (PhOCH3) parts in the structure segregate, the former inter­acting through a dense hydrogen-bonding scheme, leading to a well connected two-dimensional structure parallel to (100) and the latter hydro­phobic groups acting as spacers for an inter­planar separation of c/2 = 10.205 (2) Å. In spite of being aligned along [110], the benzene rings stack in a far from parallel fashion [viz. consecutive ring centers determine a broken line with a 164.72 (12)° zigzag angle], thus preventing any possible π–π inter­action.

Related literature

For literature on the role of weak inter­actions in supra­molecular structures, see: Desiraju (2007[Desiraju, G. R. P. (2007). Angew. Chem. Int. Ed. 46, 8342-8356.]). For related structures, see: Fewings et al. (2001[Fewings, K. R., Junk, P. C., Georganopoulou, D., Prince, P. D. & Steed, J. W. (2001). Polyhedron, 20, 643-649.]); Wang et al. (2007[Wang, K.-W., Feng, W.-J., Li, H.-Y., Ma, L.-L. & Jin, Z.-M. (2007). Acta Cryst. E63, o3481.]). For the Cambridge Structural Database, see: Allen (2002[Allen, F. H. (2002). Acta Cryst. B58, 380-388.]). For the synthesis, see: Porcheddu et al. (2009[Porcheddu, A., De Luca, L. & Giacomelli, G. (2009). Synlett, 13, 2149-2153.]).

[Scheme 1]

Experimental

Crystal data

  • NH4+·C7H7O4S−

  • Mr = 205.23

  • Orthorhombic, P 21 21 21

  • a = 6.2664 (12) Å

  • b = 7.1342 (12) Å

  • c = 20.410 (2) Å

  • V = 912.4 (2) Å3

  • Z = 4

  • Mo Kα radiation

  • μ = 0.34 mm−1

  • T = 298 K

  • 0.20 × 0.10 × 0.10 mm
Data collection

  • Oxford Diffraction Gemini CCD S Ultra diffractometer

  • Absorption correction: multi-scan (CrysAlis PRO; Oxford Diffraction, 2009[Oxford Diffraction (2009). CrysAlis PRO. Oxford Diffraction Ltd, Yarnton, Oxfordshire, England.]) Tmin = 0.958, Tmax = 0.965

  • 4265 measured reflections

  • 1732 independent reflections

  • 1548 reflections with I > 2σ(I)

  • Rint = 0.050
Refinement

  • R[F2 > 2σ(F2)] = 0.042

  • wR(F2) = 0.119

  • S = 1.04

  • 1732 reflections

  • 135 parameters

  • 21 restraints

  • H atoms treated by a mixture of independent and constrained refinement

  • Δρmax = 0.47 e Å−3

  • Δρmin = −0.36 e Å−3

  • Absolute structure: Flack (1983[Flack, H. D. (1983). Acta Cryst. A39, 876-881.]), 637 Friedel pairs

  • Flack parameter: −0.11 (14)

Table 1
Hydrogen-bond geometry (Å, °)

D—H⋯A D—H H⋯A D⋯A D—H⋯A
N1—H1N⋯O1i 0.88 (2) 1.99 (2) 2.851 (3) 170 (3)
N1—H4N⋯O2ii 0.86 (2) 1.98 (2) 2.797 (3) 160 (3)
N1—H2N⋯O3iii 0.88 (2) 1.98 (2) 2.824 (3) 162 (3)
N1—H3N⋯O3 0.87 (2) 2.04 (2) 2.890 (3) 164 (3)
Symmetry codes: (i) x-1, y, z; (ii) [x-{\script{1\over 2}}, -y+{\script{1\over 2}}, -z+1]; (iii) [x-{\script{1\over 2}}, -y+{\script{3\over 2}}, -z+1].

Data collection: CrysAlis PRO (Oxford Diffraction, 2009[Oxford Diffraction (2009). CrysAlis PRO. Oxford Diffraction Ltd, Yarnton, Oxfordshire, England.]); cell refinement: CrysAlis PRO; data reduction: CrysAlis PRO; program(s) used to solve structure: SHELXS97 (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: SHELXTL (Sheldrick, 2008[Sheldrick, G. M. (2008). Acta Cryst. A64, 112-122.]); software used to prepare material for publication: SHELXL97 and PLATON (Spek, 2009[Spek, A. L. (2009). Acta Cryst. D65, 148-155.]).

Supporting information

Crystal structure: contains datablocks I, global. DOI: https://doi.org/10.1107/S1600536812028103/qm2074sup1.cif

Structure factors: contains datablock I. DOI: https://doi.org/10.1107/S1600536812028103/qm2074Isup2.hkl

Supporting information file. DOI: https://doi.org/10.1107/S1600536812028103/qm2074Isup3.cml

checkCIF report


Comment top

The study of supramolecular systems determined by weak interactions such as hydrogen bonding, π-π stacking or dipole- dipole interactions have been, and currently are, active fields of structural research due to their implications in crystal engineering, self-assembly and, above all, biological systems (Desiraju, 2007). Derivatives of the benzenesulfonate anion are extremely suited to this end due to the possibility of π-interactions between arene rings, as well as hydrogen bonding between the sulphonate groups and any H donor eventualy available (Water, ammonium, etc). With this latter NH4 partner a number a structures of the sort have been published (among many others, ammonium p-toluenesulfonate, Fewings et al., 2001, (II); ammonium 4-hydroxybenzenesulfonate, Wang et al., 2007, (III), etc), the vast majority displaying, as expected, an extremely complex non-bonding interactions scheme. We present herein one further member in this family, ammonium 4-methoxybenzenesulfonate, C7H7O4S.H4N (I), which ended up being isotructural to (II) but different from (III), in spite of the very similar formulations.

The molecular structure in (I) (Fig 1) is featureless, with interatomic bond and angles in the expected ranges, and its main interest resides in the packing mode. Hydrophilic (SO3, NH4) and hydrophobic (PhOCH3) parts in the structure segregate, the former one interacting through a dense H-bonding scheme (Table 1) leading to a well connected two-dimensional structure, parallell to (100) (Fig 2a) and the latter hydrophobic groups acting as spacers (Figs 2 b, 2c), for an interplanar separation of C/2 = 10.205 (2) Å. In spite of the deceiving views in Figs 2 b/2c, Ph groups stack in a far from paralell fashion, defining dihedral angles of 37° and thus preventing any possible π–π interaction.

Related literature top

For literature on the role of weak interactions in supramolecular structures, see: Desiraju (2007). For related structures see: Fewings et al. (2001); Wang et al. (2007). For the Cambridge Structural Database, see: Allen (2002). For the synthesis, see: Porcheddu et al. (2009).

Experimental top

The title compound was obtained as a byproduct in the synthesis of N-hydroxy-4-methoxybenzenesulfonamide, following the procedure described in Porcheddu et al., 2009. A few light yellow crystals were obtained after evaporating an acetonitrile solution.

Refinement top

All H atoms were found in a difference map, though treated differently in refinement: C—H atoms were idealized and allowed to ride, with displacement parameters taken as Uiso(H) = X × Ueq(C) [(C—H)methyl = 0.96 A°, X = 1.5; (C—H)arom = 0.93 A°, X = 1.2] (CH3 groups were also free to rotate as well). Ammonium H's were refined with restrained N—H = 0.85 (1) Å, H···H = 1.35 (2) Å distances and free isotropic displacement factors.

Structure description top

The study of supramolecular systems determined by weak interactions such as hydrogen bonding, π-π stacking or dipole- dipole interactions have been, and currently are, active fields of structural research due to their implications in crystal engineering, self-assembly and, above all, biological systems (Desiraju, 2007). Derivatives of the benzenesulfonate anion are extremely suited to this end due to the possibility of π-interactions between arene rings, as well as hydrogen bonding between the sulphonate groups and any H donor eventualy available (Water, ammonium, etc). With this latter NH4 partner a number a structures of the sort have been published (among many others, ammonium p-toluenesulfonate, Fewings et al., 2001, (II); ammonium 4-hydroxybenzenesulfonate, Wang et al., 2007, (III), etc), the vast majority displaying, as expected, an extremely complex non-bonding interactions scheme. We present herein one further member in this family, ammonium 4-methoxybenzenesulfonate, C7H7O4S.H4N (I), which ended up being isotructural to (II) but different from (III), in spite of the very similar formulations.

The molecular structure in (I) (Fig 1) is featureless, with interatomic bond and angles in the expected ranges, and its main interest resides in the packing mode. Hydrophilic (SO3, NH4) and hydrophobic (PhOCH3) parts in the structure segregate, the former one interacting through a dense H-bonding scheme (Table 1) leading to a well connected two-dimensional structure, parallell to (100) (Fig 2a) and the latter hydrophobic groups acting as spacers (Figs 2 b, 2c), for an interplanar separation of C/2 = 10.205 (2) Å. In spite of the deceiving views in Figs 2 b/2c, Ph groups stack in a far from paralell fashion, defining dihedral angles of 37° and thus preventing any possible π–π interaction.

For literature on the role of weak interactions in supramolecular structures, see: Desiraju (2007). For related structures see: Fewings et al. (2001); Wang et al. (2007). For the Cambridge Structural Database, see: Allen (2002). For the synthesis, see: Porcheddu et al. (2009).

Computing details top

Data collection: CrysAlis PRO (Oxford Diffraction, 2009); cell refinement: CrysAlis PRO (Oxford Diffraction, 2009); data reduction: CrysAlis PRO (Oxford Diffraction, 2009); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: SHELXTL (Sheldrick, 2008); software used to prepare material for publication: SHELXL97 (Sheldrick, 2008) and PLATON (Spek, 2009).

Figures top
[Figure 1] Fig. 1. Ellipsoid plot of (I), drawn with displacement factors at a 50% probability level. Symmetry codes: (i) x - 1, y, z; (ii) x - 1/2, -y + 1/2, -z + 1; (iii) x - 1/2, -y + 3/2, -z + 1.
[Figure 2] Fig. 2. Packing views of (I). a) Projection paralell to (001) showing the hydrophilic part only and the H-bonding interactions taking place therein. Symmetry codes: as in Fig 1. b) A packing view with the whole structure, projected down [100]. Hydrophilic/hydrophobic parts (seen in projection) drawn in heavy/weak lining, respectively. c) Same as b) viewed along [010].
Ammonium 4-methoxybenzenesulfonate top
Crystal data top
NH4+·C7H7O4S−F(000) = 432
Mr = 205.23Dx = 1.494 Mg m−3
Orthorhombic, P212121Mo Kα radiation, λ = 0.71073 Å
Hall symbol: P 2ac 2abCell parameters from 2823 reflections
a = 6.2664 (12) Åθ = 2.1–25.9°
b = 7.1342 (12) ŵ = 0.34 mm−1
c = 20.410 (2) ÅT = 298 K
V = 912.4 (2) Å3Blocks, yellow
Z = 40.20 × 0.10 × 0.10 mm
Data collection top
Oxford Diffraction Gemini CCD S Ultra
diffractometer		1548 reflections with I > 2σ(I)
Graphite monochromatorRint = 0.050
ω scans, thick slicesθmax = 26.2°, θmin = 2.0°
Absorption correction: multi-scan
(CrysAlis PRO; Oxford Diffraction, 2009)		h = −7→6
Tmin = 0.958, Tmax = 0.965k = −8→8
4265 measured reflectionsl = −20→25
1732 independent reflections
Refinement top
Refinement on F2Secondary atom site location: difference Fourier map
Least-squares matrix: fullHydrogen site location: inferred from neighbouring sites
R[F2 > 2σ(F2)] = 0.042H atoms treated by a mixture of independent and constrained refinement
wR(F2) = 0.119 w = 1/[σ2(Fo2) + (0.0842P)2]
where P = (Fo2 + 2Fc2)/3
S = 1.04(Δ/σ)max < 0.001
1732 reflectionsΔρmax = 0.47 e Å−3
135 parametersΔρmin = −0.36 e Å−3
21 restraintsAbsolute structure: Flack (1983), 637 Friedel pairs
Primary atom site location: structure-invariant direct methodsAbsolute structure parameter: −0.11 (14)
Crystal data top
NH4+·C7H7O4S−V = 912.4 (2) Å3
Mr = 205.23Z = 4
Orthorhombic, P212121Mo Kα radiation
a = 6.2664 (12) ŵ = 0.34 mm−1
b = 7.1342 (12) ÅT = 298 K
c = 20.410 (2) Å0.20 × 0.10 × 0.10 mm
Data collection top
Oxford Diffraction Gemini CCD S Ultra
diffractometer		1732 independent reflections
Absorption correction: multi-scan
(CrysAlis PRO; Oxford Diffraction, 2009)		1548 reflections with I > 2σ(I)
Tmin = 0.958, Tmax = 0.965Rint = 0.050
4265 measured reflections
Refinement top
R[F2 > 2σ(F2)] = 0.042H atoms treated by a mixture of independent and constrained refinement
wR(F2) = 0.119Δρmax = 0.47 e Å−3
S = 1.04Δρmin = −0.36 e Å−3
1732 reflectionsAbsolute structure: Flack (1983), 637 Friedel pairs
135 parametersAbsolute structure parameter: −0.11 (14)
21 restraints
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.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top
xyzUiso*/Ueq
S10.95549 (11)0.47643 (10)0.59811 (3)0.0305 (2)
O11.1864 (3)0.4832 (4)0.59781 (11)0.0483 (6)
O20.8694 (4)0.3085 (3)0.56840 (11)0.0422 (6)
O30.8578 (4)0.6413 (3)0.56824 (11)0.0379 (6)
O40.7122 (4)0.4778 (4)0.87726 (9)0.0426 (6)
C10.8765 (4)0.4753 (4)0.68155 (13)0.0295 (6)
C20.6702 (4)0.5282 (5)0.69849 (13)0.0324 (6)
H20.57340.56160.66600.039*
C30.6087 (4)0.5311 (5)0.76355 (13)0.0338 (6)
H30.47130.56770.77510.041*
C40.7550 (5)0.4783 (4)0.81175 (13)0.0324 (6)
C50.9583 (6)0.4232 (4)0.79423 (15)0.0375 (7)
H51.05440.38630.82650.045*
C61.0207 (5)0.4223 (4)0.72898 (14)0.0335 (6)
H61.15830.38640.71740.040*
C70.5125 (6)0.5513 (6)0.89746 (15)0.0498 (8)
H7A0.50910.55980.94440.075*
H7B0.40010.47000.88280.075*
H7C0.49310.67370.87890.075*
N10.4879 (3)0.5244 (3)0.49420 (10)0.0264 (5)
H1N0.391 (3)0.526 (4)0.5251 (9)0.034 (8)*
H2N0.463 (5)0.619 (3)0.4678 (12)0.068 (13)*
H3N0.612 (3)0.542 (5)0.5125 (10)0.039 (9)*
H4N0.484 (5)0.421 (3)0.4729 (13)0.069 (14)*
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
S10.0297 (3)0.0358 (3)0.0261 (3)−0.0015 (3)0.0015 (3)−0.0013 (3)
O10.0310 (11)0.0745 (17)0.0394 (12)0.0018 (12)0.0032 (9)−0.0021 (15)
O20.0533 (16)0.0399 (12)0.0336 (12)−0.0030 (10)0.0042 (12)−0.0044 (10)
O30.0454 (13)0.0370 (11)0.0313 (12)−0.0024 (10)−0.0004 (11)0.0042 (10)
O40.0491 (12)0.0521 (13)0.0265 (10)0.0068 (12)−0.0010 (9)0.0003 (11)
C10.0305 (12)0.0307 (13)0.0273 (13)−0.0035 (12)0.0009 (11)−0.0001 (12)
C20.0300 (13)0.0393 (14)0.0279 (13)−0.0026 (13)−0.0045 (11)0.0008 (14)
C30.0286 (13)0.0402 (15)0.0327 (14)0.0001 (12)0.0023 (11)−0.0037 (14)
C40.0390 (14)0.0313 (13)0.0268 (13)−0.0036 (13)−0.0006 (11)−0.0015 (13)
C50.0416 (16)0.0377 (15)0.0331 (15)0.0081 (14)−0.0069 (14)0.0024 (12)
C60.0331 (15)0.0333 (13)0.0342 (14)0.0060 (12)−0.0021 (12)−0.0019 (11)
C70.0438 (17)0.076 (2)0.0292 (15)−0.0005 (18)0.0048 (14)−0.0050 (17)
N10.0247 (10)0.0303 (10)0.0241 (10)0.0038 (9)−0.0026 (9)0.0019 (10)
Geometric parameters (Å, º) top
S1—O21.447 (2)C4—C51.380 (4)
S1—O11.448 (2)C5—C61.388 (4)
S1—O31.459 (2)C5—H50.9300
S1—C11.773 (3)C6—H60.9300
O4—C41.364 (3)C7—H7A0.9600
O4—C71.418 (4)C7—H7B0.9600
C1—C61.377 (4)C7—H7C0.9600
C1—C21.390 (4)N1—H1N0.876 (15)
C2—C31.383 (4)N1—H2N0.877 (16)
C2—H20.9300N1—H3N0.873 (16)
C3—C41.396 (4)N1—H4N0.858 (16)
C3—H30.9300
O2—S1—O1113.48 (17)C4—C5—C6120.7 (3)
O2—S1—O3109.62 (13)C4—C5—H5119.7
O1—S1—O3112.99 (16)C6—C5—H5119.7
O2—S1—C1107.15 (14)C1—C6—C5119.2 (3)
O1—S1—C1106.45 (13)C1—C6—H6120.4
O3—S1—C1106.71 (14)C5—C6—H6120.4
C4—O4—C7117.2 (2)O4—C7—H7A109.5
C6—C1—C2120.6 (3)O4—C7—H7B109.5
C6—C1—S1119.6 (2)H7A—C7—H7B109.5
C2—C1—S1119.8 (2)O4—C7—H7C109.5
C3—C2—C1120.1 (3)H7A—C7—H7C109.5
C3—C2—H2119.9H7B—C7—H7C109.5
C1—C2—H2119.9H1N—N1—H2N108 (3)
C2—C3—C4119.3 (3)H1N—N1—H3N108 (3)
C2—C3—H3120.4H2N—N1—H3N108 (3)
C4—C3—H3120.4H1N—N1—H4N111 (3)
O4—C4—C5115.8 (3)H2N—N1—H4N110 (3)
O4—C4—C3124.2 (3)H3N—N1—H4N111 (3)
C5—C4—C3120.0 (3)
Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
N1—H1N···O1i0.88 (2)1.99 (2)2.851 (3)170 (3)
N1—H4N···O2ii0.86 (2)1.98 (2)2.797 (3)160 (3)
N1—H2N···O3iii0.88 (2)1.98 (2)2.824 (3)162 (3)
N1—H3N···O30.87 (2)2.04 (2)2.890 (3)164 (3)
Symmetry codes: (i) x−1, y, z; (ii) x−1/2, −y+1/2, −z+1; (iii) x−1/2, −y+3/2, −z+1.

Experimental details

Crystal data
Chemical formulaNH4+·C7H7O4S−
Mr205.23
Crystal system, space groupOrthorhombic, P212121
Temperature (K)298
a, b, c (Å)6.2664 (12), 7.1342 (12), 20.410 (2)
V (Å3)912.4 (2)
Z4
Radiation typeMo Kα
µ (mm−1)0.34
Crystal size (mm)0.20 × 0.10 × 0.10
Data collection
DiffractometerOxford Diffraction Gemini CCD S Ultra
Absorption correctionMulti-scan
(CrysAlis PRO; Oxford Diffraction, 2009)
Tmin, Tmax0.958, 0.965
No. of measured, independent and
observed [I > 2σ(I)] reflections		4265, 1732, 1548
Rint0.050
(sin θ/λ)max (Å−1)0.622
Refinement
R[F2 > 2σ(F2)], wR(F2), S 0.042, 0.119, 1.04
No. of reflections1732
No. of parameters135
No. of restraints21
H-atom treatmentH atoms treated by a mixture of independent and constrained refinement
Δρmax, Δρmin (e Å−3)0.47, −0.36
Absolute structureFlack (1983), 637 Friedel pairs
Absolute structure parameter−0.11 (14)

Computer programs: CrysAlis PRO (Oxford Diffraction, 2009), SHELXS97 (Sheldrick, 2008), SHELXTL (Sheldrick, 2008), SHELXL97 (Sheldrick, 2008) and PLATON (Spek, 2009).

Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
N1—H1N···O1i0.876 (15)1.985 (17)2.851 (3)170 (3)
N1—H4N···O2ii0.858 (16)1.977 (18)2.797 (3)160 (3)
N1—H2N···O3iii0.877 (16)1.976 (18)2.824 (3)162 (3)
N1—H3N···O30.873 (16)2.040 (17)2.890 (3)164 (3)
Symmetry codes: (i) x−1, y, z; (ii) x−1/2, −y+1/2, −z+1; (iii) x−1/2, −y+3/2, −z+1.
 

Footnotes

‡Author to whom enquiries should be addressed, e-mail: doctorovich@qi.fcen.uba.ar.

Acknowledgements

The authors acknowledge ANPCyT (project No. PME 2006–01113) for the purchase of the Oxford Gemini CCD diffractometer and the Spanish Research Council (CSIC) for the provision of a free-of-charge licence to the Cambridge Structural Database (Allen, 2002[Allen, F. H. (2002). Acta Cryst. B58, 380-388.]).

References

First citationAllen, F. H. (2002). Acta Cryst. B58, 380–388.  Web of Science CSD CrossRef CAS IUCr Journals Google Scholar
 First citationDesiraju, G. R. P. (2007). Angew. Chem. Int. Ed. 46, 8342–8356.  Web of Science CrossRef CAS Google Scholar
 First citationFewings, K. R., Junk, P. C., Georganopoulou, D., Prince, P. D. & Steed, J. W. (2001). Polyhedron, 20, 643–649.  Web of Science CSD CrossRef CAS Google Scholar
 First citationFlack, H. D. (1983). Acta Cryst. A39, 876–881.  CrossRef CAS Web of Science IUCr Journals Google Scholar
 First citationOxford Diffraction (2009). CrysAlis PRO. Oxford Diffraction Ltd, Yarnton, Oxfordshire, England.  Google Scholar
 First citationPorcheddu, A., De Luca, L. & Giacomelli, G. (2009). Synlett, 13, 2149–2153.  Web of Science CrossRef Google Scholar
 First citationSheldrick, G. M. (2008). Acta Cryst. A64, 112–122.  Web of Science CrossRef CAS IUCr Journals Google Scholar
 First citationSpek, A. L. (2009). Acta Cryst. D65, 148–155.  Web of Science CrossRef CAS IUCr Journals Google Scholar
 First citationWang, K.-W., Feng, W.-J., Li, H.-Y., Ma, L.-L. & Jin, Z.-M. (2007). Acta Cryst. E63, o3481.  Web of Science CSD CrossRef IUCr Journals Google Scholar

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COMMUNICATIONS
ISSN: 2056-9890
Volume 68| Part 7| July 2012| Pages o2228-o2229
https://doi.org/10.1107/S1600536812028103
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