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

Journal logoCRYSTALLOGRAPHIC
COMMUNICATIONS
ISSN: 2056-9890
Volume 69| Part 6| June 2013| Pages o981-o982

4-Cyano-1-methyl­pyridinium nitrate

aDepartment of Physics, Loyola University, New Orleans, LA 70118, USA, bDepartment of Chemistry, Loyola University, New Orleans, LA 70118, USA, and cDepartment of Chemistry, Tulane University, New Orleans, LA 70118, USA
*Correspondence e-mail: joelt@tulane.edu

(Received 29 April 2013; accepted 20 May 2013; online 31 May 2013)

The title mol­ecular salt, C7H7N2+·NO3, displays an inter­penetrating sheet structure parallel to a with each sheet containing nearly coplanar cations and anions, each ion being bis­ected by a crystallographic mirror plane. C—H⋯O hydrogen bonds involving both ring and methyl H atoms in addition to cation–cation C—H⋯N hydrogen bonds (ring H to cyano N) serve to link the sheets together. In each set of parallel layers, the cations and anions stack with short distances of 3.094 (2) (between aligned nitrate N and pyridine N atoms) and 3.057 (2) Å (between a nitrate O atom and the ring centroid). This motif is strikingly similar to the one that features in the isomeric salt 2-cyano-1-methyl­pyridinium nitrate.

Related literature

For structures of other 4-cyano-1-methyl­pyridinium salts, see: Bockman & Kochi (1989[Bockman, T. M. & Kochi, J. A. (1989). J. Am. Chem. Soc. 111, 4669-4683.]); Bockman & Kochi (1992[Bockman, T. M. & Kochi, J. K. (1992). New J. Chem. 16, 39-49.]); Hardacre et al. (2008[Hardacre, C., Holbrey, J. D., Mullan, C. L., Nieuwenhuyzen, M., Reichert, W. M., Seddon, K. R. & Teat, S. J. (2008). New J. Chem. 32, 1953-1967.], 2010[Hardacre, C., Holbrey, J. D., Mullan, C. L., Nieuwenhuyzen, M., Youngs, T. G. A., Bowron, D. T. & Teat, S. J. (2010). Phys. Chem. Chem. Phys. 12, 1842-1853.]); Kammer et al. (2012a[Kammer, M. N., Mague, J. T. & Koplitz, L. V. (2012a). Acta Cryst. E68, o2409.],b[Kammer, M. N., Koplitz, L. V. & Mague, J. T. (2012b). Acta Cryst. E68, o2514.]. For the structure of 2-cyano-1-methyl­pyridinium nitrate, see: Koplitz et al. (2012[Koplitz, L. V., Mague, J. T., Kammer, M. N., McCormick, C. A., Renfro, H. E. & Vumbaco, D. J. (2012). Acta Cryst. E68, o1653.]), of 3-cyano-1-methyl­pyridinium chloride, see: Koplitz et al. (2003[Koplitz, L. V., Bay, K. D., DiGiovanni, N. & Mague, J. T. (2003). J. Chem. Crystallogr. 33, 391-402.]) and of 3-cyano-N-methyl­pyridinium bromide, see: Mague et al. (2005[Mague, J. T., Ivie, R. M., Hartsock, R. W., Koplitz, L. V. & Spulak, M. (2005). Acta Cryst. E61, o851-o853.]). For a discussion of anion–π inter­actions, see: Frontera et al. (2011[Frontera, A., Gamez, P., Mascal, M., Mooibroeck, T. J. & Reedijk, J. (2011). Angew. Chem. Int. Ed. 50, 9564-9583.]). For the structure of 2-cyano­anilinium nitrate, see: Cui & Wen (2008[Cui, L.-J. & Wen, X.-C. (2008). Acta Cryst. E64, o1620.]) and of 3-cyano­anilinium nitrate, see: Wang (2009[Wang, B. (2009). Acta Cryst. E65, o2395.]).

[Scheme 1]

Experimental

Crystal data
  • C7H7N2+·NO3

  • Mr = 181.16

  • Orthorhombic, P m n 21

  • a = 8.195 (3) Å

  • b = 7.289 (3) Å

  • c = 6.721 (3) Å

  • V = 401.5 (3) Å3

  • Z = 2

  • Mo Kα radiation

  • μ = 0.12 mm−1

  • T = 100 K

  • 0.33 × 0.23 × 0.13 mm

Data collection
  • Bruker SMART APEX CCD diffractometer

  • Absorption correction: multi-scan (TWINABS; Sheldrick, 2009[Sheldrick, G. M. (2009). TWINABS. University of Göttingen, Germany.]) Tmin = 0.860, Tmax = 0.985

  • 6751 measured reflections

  • 1116 independent reflections

  • 1089 reflections with I > 2σ(I)

  • Rint = 0.091

Refinement
  • R[F2 > 2σ(F2)] = 0.038

  • wR(F2) = 0.092

  • S = 1.09

  • 1116 reflections

  • 71 parameters

  • 1 restraint

  • H-atom parameters constrained

  • Δρmax = 0.40 e Å−3

  • Δρmin = −0.43 e Å−3

Table 1
Hydrogen-bond geometry (Å, °)

D—H⋯A D—H H⋯A DA D—H⋯A
C1—H1A⋯O1i 0.96 2.71 3.3826 (19) 127
C1—H1A⋯O1ii 0.96 2.71 3.3826 (19) 127
C1—H1B⋯O1iii 0.90 2.60 3.4485 (15) 159
C2—H2⋯O1iv 0.95 2.65 3.3763 (17) 134
C2—H2⋯O2iv 0.95 2.29 3.2379 (15) 172
C3—H3⋯N2iv 0.95 2.51 3.2272 (15) 132
C3—H3⋯O1v 0.95 2.56 3.2568 (17) 131
Symmetry codes: (i) x, y-1, z; (ii) -x+1, y-1, z; (iii) [x-{\script{1\over 2}}, -y+1, z+{\script{1\over 2}}]; (iv) [-x+{\script{3\over 2}}, -y+1, z+{\script{1\over 2}}]; (v) [-x+{\script{3\over 2}}, -y+1, z-{\script{1\over 2}}].

Data collection: APEX2 (Bruker, 2010[Bruker (2010). APEX2. Bruker AXS Inc., Madison, Wisconsin, USA.]); cell refinement: SAINT (Bruker, 2009[Bruker (2009). SAINT. Bruker AXS Inc., Madison, Wisconsin, USA.]); data reduction: SAINT; program(s) used to solve structure: FLIPPER option in PLATON (Spek, 2009[Spek, A. L. (2009). Acta Cryst. D65, 148-155.]); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008[Sheldrick, G. M. (2008). Acta Cryst. A64, 112-122.]); molecular graphics: DIAMOND (Brandenburg & Putz, 2012[Brandenburg, K. & Putz, H. (2012). DIAMOND. Crystal Impact GbR, Bonn, Germany.]); software used to prepare material for publication: SHELXTL (Sheldrick, 2008[Sheldrick, G. M. (2008). Acta Cryst. A64, 112-122.]).

Supporting information


Comment top

A perspective view of the title compound appears in Fig. 1 while Fig. 2 illustrates the interpenetrating sets of parallel cation/anion sheets. Within each layer, the dihedral angle between mean cation and anion planes is 1.63 (3)° while the two sets of layers are inclined at an angle of 60.05 (4)°. The majority of the interionic interactions are C—H···O hydrogen bonds between cations in one set of layers and anions in the other set. Additionally there are C—H···N interactions between ring H atoms of cations in one set of layers and the cyano groups of cations in the other set (Table 1 and Fig. 3). A notable feature is the close interlayer cation-anion contact which is strikingly similar to the motif that dominates the structure of 2-cyano-1-methylpyridinium nitrate. (Koplitz et al., 2012). Thus, the N3—O2 bond of one anion is oriented with O2 lying directly over the centroid of the nearest parallel pyridinium ring at a distance of 3.057 (2) Å and N3 lying directly over the pyridinium nitrogen (N1) at a distance of 3.094 (2) Å. These close contacts are likely the result of electrostatic cation-anion attraction with the orientation possibly reinforced by an anion-π interaction (Frontera et al., 2011). In contrast to the structure found for the title compound, the structures of the isomeric salts 2-cyano-1-methylpyridinium nitrate (Koplitz et al., 2012) and 2-cyanoanilinium nitrate (Cui & Wen, 2008) crystallize in flat layers of two-dimensional networks with only a few atoms protruding from the mirror plane while 3-cyanoanilinium nitrate (Wang, 2009) forms a more open structure.

Related literature top

For structures of other 4-cyano-1-methylpyridinium salts, see: Bockman & Kochi (1989); Bockman & Kochi (1992); Hardacre et al. (2008, 2010); Kammer et al. (2012a,b. For the structure of 2-cyano-1-methylpyridinium nitrate, see: Koplitz et al. (2012), of 3-cyano-1-methylpyridinium chloride, see: Koplitz et al. (2003) and of 3-cyano-N-methylpyridinium bromide, see: Mague et al. (2005). For a discussion of anion–π interactions, see: Frontera et al. (2011). For the structure of 2-cyanoanilinium nitrate, see: Cui & Wen (2008) and of 3-cyanoanilinium nitrate, see: Wang (2009).

Experimental top

4-Cyanopyridine (10.55 g) was dissolved in benzene (40 ml). Iodomethane (9.5 ml) was added to this solution slowly with stirring and the solution was refluxed for 75 minutes. Yellow solid 4-cyano-N-methylpyridinium iodide (m.p. 189–193° C) was collected by vacuum filtration. This solid (0.226 g) was then dissolved in ethanol (20.3 ml) along with an equimolar amount lead(II) nitrate (0.1487 g). Precipitated PbI2 was removed by vacuum filtration and the filtrate containing 4-cyano-N-methylpyridinium nitrate was slowly evaporated to dryness to form colourless blocks of the title compound.

Refinement top

H-atoms were placed in calculated positions (C—H = 0.95 - 0.98 Å) and included as riding contributions with isotropic displacement parameters 1.2 - 1.5 times those of the attached carbon atoms. Because both ions sit on the mirror plane, the methyl group H atoms are disordered across the mirror. Trial refinements with both the one-component reflection file extracted from the full data set with TWINABS and with the full two-component file showed that use of the former provided a better refinement.

Computing details top

Data collection: APEX2 (Bruker, 2010); cell refinement: SAINT (Bruker, 2009); data reduction: SAINT (Bruker, 2009); program(s) used to solve structure: PLATON (Spek, 2009); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: DIAMOND (Brandenburg & Putz, 2012); software used to prepare material for publication: SHELXTL (Sheldrick, 2008).

Figures top
[Figure 1] Fig. 1. Perspective view of I with displacement ellipsoids drawn at the 50% probability level and H-atoms as spheres of arbitrary radius. Primed atoms are related to unprimed counterparts by 1-x, y, z.
[Figure 2] Fig. 2. Packing of I viewed down a showing the interpenetrating layers. The C—H···O and C—H···N interactions are shown as dashed lines.
[Figure 3] Fig. 3. Packing of I showing the anion–π interactions as dashed lines.
4-Cyano-1-methylpyridinium nitrate top
Crystal data top
C7H7N2+·NO3F(000) = 188
Mr = 181.16Dx = 1.499 Mg m3
Orthorhombic, Pmn21Mo Kα radiation, λ = 0.71073 Å
Hall symbol: P 2ac -2Cell parameters from 5849 reflections
a = 8.195 (3) Åθ = 2.8–29.1°
b = 7.289 (3) ŵ = 0.12 mm1
c = 6.721 (3) ÅT = 100 K
V = 401.5 (3) Å3Block, colourless
Z = 20.33 × 0.23 × 0.13 mm
Data collection top
Bruker SMART APEX CCD
diffractometer
1116 independent reflections
Radiation source: fine-focus sealed tube1089 reflections with I > 2σ(I)
Graphite monochromatorRint = 0.091
ϕ and ω scansθmax = 29.1°, θmin = 2.8°
Absorption correction: multi-scan
(TWINABS; Sheldrick, 2009)
h = 1111
Tmin = 0.860, Tmax = 0.985k = 99
6751 measured reflectionsl = 98
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)] = 0.038H-atom parameters constrained
wR(F2) = 0.092 w = 1/[σ2(Fo2) + (0.0602P)2 + 0.031P]
where P = (Fo2 + 2Fc2)/3
S = 1.09(Δ/σ)max < 0.001
1116 reflectionsΔρmax = 0.40 e Å3
71 parametersΔρmin = 0.43 e Å3
1 restraintExtinction correction: SHELXL (Sheldrick, 2008), Fc*=kFc[1+0.001xFc2λ3/sin(2θ)]-1/4
Primary atom site location: structure-invariant direct methodsExtinction coefficient: 0.098 (15)
Crystal data top
C7H7N2+·NO3V = 401.5 (3) Å3
Mr = 181.16Z = 2
Orthorhombic, Pmn21Mo Kα radiation
a = 8.195 (3) ŵ = 0.12 mm1
b = 7.289 (3) ÅT = 100 K
c = 6.721 (3) Å0.33 × 0.23 × 0.13 mm
Data collection top
Bruker SMART APEX CCD
diffractometer
1116 independent reflections
Absorption correction: multi-scan
(TWINABS; Sheldrick, 2009)
1089 reflections with I > 2σ(I)
Tmin = 0.860, Tmax = 0.985Rint = 0.091
6751 measured reflections
Refinement top
R[F2 > 2σ(F2)] = 0.0381 restraint
wR(F2) = 0.092H-atom parameters constrained
S = 1.09Δρmax = 0.40 e Å3
1116 reflectionsΔρmin = 0.43 e Å3
71 parameters
Special details top

Experimental. The diffraction data were obtained from 3 sets of 400 frames, each of width 0.5° in ω, collected at ϕ = 0.00, 90.00 and 180.00° and 2 sets of 800 frames, each of width 0.45\5 in ϕ, collected at ω = -30.00 and 210.00°. The scan time was 15 sec/frame. Analysis of 427 reflections chosen from the full data set and having I/σ(I) > 15.0 with CELL_NOW (Sheldrick, 2008a) showed the crystal to belong to the orthorhombic system and to be twinned by a 180° rotation about c. The raw data were processed with SAINT under control of the 2-component orientation file generated by CELL_NOW.

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. H-atoms were placed in positions derived from a difference map and their coordinates adjusted to give C—H = 0.95 Å (aromatic) and 0.98 Å (aliphatic). All were included as riding contributions with isotropic displacement parameters 1.2 - 1.5 times those of the attached carbon atoms.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top
xyzUiso*/Ueq
N10.50000.16216 (16)0.63902 (16)0.0149 (3)
N20.50000.51281 (19)0.0553 (2)0.0246 (3)
C10.50000.0548 (2)0.8274 (2)0.0191 (3)
H1A0.50000.07460.79800.029*
H1B0.40890.08250.89490.029*
C20.64416 (13)0.20717 (15)0.55473 (14)0.0168 (2)
H20.74340.17530.61920.020*
C30.64799 (13)0.29942 (14)0.37491 (15)0.0163 (2)
H30.74890.33090.31420.020*
C40.50000.34509 (18)0.2849 (2)0.0146 (3)
C50.50000.4394 (2)0.0962 (2)0.0175 (3)
N30.50000.80142 (16)0.39635 (19)0.0154 (3)
O10.63291 (10)0.75855 (13)0.47555 (13)0.0244 (2)
O20.50000.89102 (15)0.23498 (16)0.0202 (3)
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
N10.0165 (7)0.0168 (5)0.0114 (6)0.0000.0000.0014 (5)
N20.0183 (7)0.0289 (7)0.0267 (6)0.0000.0000.0087 (6)
C10.0233 (9)0.0218 (7)0.0121 (6)0.0000.0000.0014 (5)
C20.0139 (5)0.0200 (5)0.0165 (5)0.0001 (3)0.0018 (4)0.0028 (4)
C30.0136 (5)0.0189 (4)0.0164 (5)0.0016 (4)0.0010 (4)0.0009 (4)
C40.0161 (7)0.0140 (6)0.0138 (7)0.0000.0000.0018 (5)
C50.0134 (7)0.0183 (6)0.0209 (7)0.0000.0000.0011 (5)
N30.0177 (7)0.0144 (5)0.0140 (6)0.0000.0000.0026 (5)
O10.0179 (4)0.0329 (4)0.0224 (4)0.0042 (3)0.0036 (3)0.0043 (3)
O20.0205 (6)0.0265 (5)0.0138 (5)0.0000.0000.0035 (4)
Geometric parameters (Å, º) top
N1—C2i1.3506 (12)C3—C41.3955 (13)
N1—C21.3506 (12)C3—H30.9500
N1—C11.4887 (18)C4—C3i1.3955 (13)
N2—C51.150 (2)C4—C51.443 (2)
C1—H1A0.9638N3—O1i1.2519 (11)
C1—H1B0.8964N3—O11.2520 (11)
C2—C31.3834 (15)N3—O21.2660 (17)
C2—H20.9500
C2i—N1—C2122.01 (12)C2—C3—H3120.8
C2i—N1—C1118.98 (6)C4—C3—H3120.8
C2—N1—C1118.98 (6)C3i—C4—C3120.70 (13)
N1—C1—H1A109.9C3i—C4—C5119.65 (7)
N1—C1—H1B108.2C3—C4—C5119.65 (7)
H1A—C1—H1B108.9N2—C5—C4179.23 (15)
N1—C2—C3120.29 (10)O1i—N3—O1120.92 (13)
N1—C2—H2119.9O1i—N3—O2119.54 (6)
C3—C2—H2119.9O1—N3—O2119.54 (6)
C2—C3—C4118.35 (10)
C2i—N1—C2—C31.14 (19)C2—C3—C4—C3i0.29 (18)
C1—N1—C2—C3176.98 (10)C2—C3—C4—C5179.29 (11)
N1—C2—C3—C40.41 (15)
Symmetry code: (i) x+1, y, z.
Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
C1—H1A···O1ii0.962.713.3826 (19)127
C1—H1A···O1iii0.962.713.3826 (19)127
C1—H1B···O1iv0.902.603.4485 (15)159
C2—H2···O1v0.952.653.3763 (17)134
C2—H2···O2v0.952.293.2379 (15)172
C3—H3···N2v0.952.513.2272 (15)132
C3—H3···O1vi0.952.563.2568 (17)131
Symmetry codes: (ii) x, y1, z; (iii) x+1, y1, z; (iv) x1/2, y+1, z+1/2; (v) x+3/2, y+1, z+1/2; (vi) x+3/2, y+1, z1/2.

Experimental details

Crystal data
Chemical formulaC7H7N2+·NO3
Mr181.16
Crystal system, space groupOrthorhombic, Pmn21
Temperature (K)100
a, b, c (Å)8.195 (3), 7.289 (3), 6.721 (3)
V3)401.5 (3)
Z2
Radiation typeMo Kα
µ (mm1)0.12
Crystal size (mm)0.33 × 0.23 × 0.13
Data collection
DiffractometerBruker SMART APEX CCD
diffractometer
Absorption correctionMulti-scan
(TWINABS; Sheldrick, 2009)
Tmin, Tmax0.860, 0.985
No. of measured, independent and
observed [I > 2σ(I)] reflections
6751, 1116, 1089
Rint0.091
(sin θ/λ)max1)0.685
Refinement
R[F2 > 2σ(F2)], wR(F2), S 0.038, 0.092, 1.09
No. of reflections1116
No. of parameters71
No. of restraints1
H-atom treatmentH-atom parameters constrained
Δρmax, Δρmin (e Å3)0.40, 0.43

Computer programs: APEX2 (Bruker, 2010), SAINT (Bruker, 2009), PLATON (Spek, 2009), SHELXL97 (Sheldrick, 2008), DIAMOND (Brandenburg & Putz, 2012), SHELXTL (Sheldrick, 2008).

Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
C1—H1A···O1i0.962.713.3826 (19)127
C1—H1A···O1ii0.962.713.3826 (19)127
C1—H1B···O1iii0.902.603.4485 (15)159
C2—H2···O1iv0.952.653.3763 (17)134
C2—H2···O2iv0.952.293.2379 (15)172
C3—H3···N2iv0.952.513.2272 (15)132
C3—H3···O1v0.952.563.2568 (17)131
Symmetry codes: (i) x, y1, z; (ii) x+1, y1, z; (iii) x1/2, y+1, z+1/2; (iv) x+3/2, y+1, z+1/2; (v) x+3/2, y+1, z1/2.
 

Acknowledgements

We thank the Chemistry Department of Tulane University for support of the X-ray laboratory and the Louisiana Board of Regents through the Louisiana Educational Quality Support Fund [grant LEQSF (2003–2003)-ENH –TR-67] for the purchase of the diffractometer.

References

First citationBockman, T. M. & Kochi, J. A. (1989). J. Am. Chem. Soc. 111, 4669–4683.  CSD CrossRef CAS Web of Science
First citationBockman, T. M. & Kochi, J. K. (1992). New J. Chem. 16, 39–49.  CAS
First citationBrandenburg, K. & Putz, H. (2012). DIAMOND. Crystal Impact GbR, Bonn, Germany.
First citationBruker (2009). SAINT. Bruker AXS Inc., Madison, Wisconsin, USA.
First citationBruker (2010). APEX2. Bruker AXS Inc., Madison, Wisconsin, USA.
First citationCui, L.-J. & Wen, X.-C. (2008). Acta Cryst. E64, o1620.  Web of Science CSD CrossRef IUCr Journals
First citationFrontera, A., Gamez, P., Mascal, M., Mooibroeck, T. J. & Reedijk, J. (2011). Angew. Chem. Int. Ed. 50, 9564–9583.  Web of Science CrossRef CAS
First citationHardacre, C., Holbrey, J. D., Mullan, C. L., Nieuwenhuyzen, M., Reichert, W. M., Seddon, K. R. & Teat, S. J. (2008). New J. Chem. 32, 1953–1967.  Web of Science CSD CrossRef CAS
First citationHardacre, C., Holbrey, J. D., Mullan, C. L., Nieuwenhuyzen, M., Youngs, T. G. A., Bowron, D. T. & Teat, S. J. (2010). Phys. Chem. Chem. Phys. 12, 1842–1853.  Web of Science CSD CrossRef CAS PubMed
First citationKammer, M. N., Koplitz, L. V. & Mague, J. T. (2012b). Acta Cryst. E68, o2514.  CSD CrossRef IUCr Journals
First citationKammer, M. N., Mague, J. T. & Koplitz, L. V. (2012a). Acta Cryst. E68, o2409.  CSD CrossRef IUCr Journals
First citationKoplitz, L. V., Bay, K. D., DiGiovanni, N. & Mague, J. T. (2003). J. Chem. Crystallogr. 33, 391–402.  Web of Science CSD CrossRef CAS
First citationKoplitz, L. V., Mague, J. T., Kammer, M. N., McCormick, C. A., Renfro, H. E. & Vumbaco, D. J. (2012). Acta Cryst. E68, o1653.  CSD CrossRef IUCr Journals
First citationMague, J. T., Ivie, R. M., Hartsock, R. W., Koplitz, L. V. & Spulak, M. (2005). Acta Cryst. E61, o851–o853.  Web of Science CSD CrossRef CAS IUCr Journals
First citationSheldrick, G. M. (2008). Acta Cryst. A64, 112–122.  Web of Science CrossRef CAS IUCr Journals
First citationSheldrick, G. M. (2009). TWINABS. University of Göttingen, Germany.
First citationSpek, A. L. (2009). Acta Cryst. D65, 148–155.  Web of Science CrossRef CAS IUCr Journals
First citationWang, B. (2009). Acta Cryst. E65, o2395.  Web of Science CSD CrossRef IUCr Journals

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.

Journal logoCRYSTALLOGRAPHIC
COMMUNICATIONS
ISSN: 2056-9890
Volume 69| Part 6| June 2013| Pages o981-o982
Follow Acta Cryst. E
Sign up for e-alerts
Follow Acta Cryst. on Twitter
Follow us on facebook
Sign up for RSS feeds