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

Journal logoCRYSTALLOGRAPHIC
COMMUNICATIONS
ISSN: 2056-9890

4-(4-Meth­oxy­phen­yl)piperazin-1-ium chloride

aDepartment of Chemistry, Quaid-i-Azam University, Islamabad 45320, Pakistan, bUniversity of Sargodha, Department of Physics, Sargodha, Pakistan, and cUniversity of Sargodha, Department of Chemistry, Sargodha, Pakistan
*Correspondence e-mail: dmntahir_uos@yahoo.com

(Received 2 February 2009; accepted 5 February 2009; online 11 February 2009)

In the title compound, C11H17N2O+·Cl, the dihedral angle between the benzene ring and the basal plane of piperazine ring is 39.20 (8)°. In the crystal, intermolecular N—H⋯Cl hydrogen bonds occur. There is also a C—H⋯π inter­action between the benzene rings.

Related literature

The title compound was obtained as a by-product in a contin­uation of work on the synthesis of tin complexes containing piperazine, see: Zia-ur-Rahman et al. (2006[Zia-ur-Rahman, Ali, S., Muhammad, N. & Meetsma, A. (2006). Acta Cryst. E62, m3560-m3561.], 2007[Zia-ur-Rahman, Ali, S., Muhammed, N. & Meetsma, A. (2007). Acta Cryst. E63, m89-m90.]). For related structures, see: Lu (2007[Lu, Y.-X. (2007). Acta Cryst. E63, o3611.]); Sadiq-ur-Rehman et al. (2007[Sadiq-ur-Rehman, Saeed, S., Ali, S., Shahzadi, S. & Helliwell, M. (2007). Acta Cryst. E63, o4526.]).

[Scheme 1]

Experimental

Crystal data
  • C11H17N2O+·Cl

  • Mr = 228.72

  • Orthorhombic, I b a 2

  • a = 10.2890 (7) Å

  • b = 31.5218 (18) Å

  • c = 7.5909 (5) Å

  • V = 2461.9 (3) Å3

  • Z = 8

  • Mo Kα radiation

  • μ = 0.29 mm−1

  • T = 296 (2) K

  • 0.28 × 0.22 × 0.15 mm

Data collection
  • Bruker KAPPA APEXII CCD diffractometer

  • Absorption correction: multi-scan (SADABS; Bruker, 2005[Bruker (2005). SADABS. Bruker AXS Inc. Madison, Wisconsin, USA.]) Tmin = 0.922, Tmax = 0.950

  • 7605 measured reflections

  • 3073 independent reflections

  • 2327 reflections with I > 2σ(I)

  • Rint = 0.026

Refinement
  • R[F2 > 2σ(F2)] = 0.044

  • wR(F2) = 0.139

  • S = 1.01

  • 3073 reflections

  • 137 parameters

  • 1 restraint

  • H-atom parameters constrained

  • Δρmax = 0.35 e Å−3

  • Δρmin = −0.29 e Å−3

  • Absolute structure: Flack (1983[Flack, H. D. (1983). Acta Cryst. A39, 876-881.]), 1076 Friedel pairs

  • Flack parameter: 0.05 (9)

Table 1
Hydrogen-bond geometry (Å, °)

D—H⋯A D—H H⋯A DA D—H⋯A
N2—H2A⋯Cl1i 0.90 2.20 3.082 (2) 168
N2—H2B⋯Cl1 0.90 2.24 3.134 (3) 177
C3—H3⋯CgAii 0.93 2.88 3.573 (2) 133
Symmetry codes: (i) [x, -y, z+{\script{1\over 2}}]; (ii) [-x+{\script{1\over 2}}, -y+{\script{1\over 2}}, z-{\script{1\over 2}}]. CgA is the centroid of the benzene ring.

Data collection: APEX2 (Bruker, 2007[Bruker (2007). APEX2 and SAINT. Bruker AXS Inc. Madison, Wisconsin, USA.]); cell refinement: SAINT (Bruker, 2007[Bruker (2007). APEX2 and SAINT. Bruker AXS Inc. Madison, Wisconsin, USA.]); data reduction: SAINT; 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: ORTEP-3 for Windows (Farrugia, 1997[Farrugia, L. J. (1997). J. Appl. Cryst. 30, 565.]) and PLATON (Spek, 2009[Spek, A. L. (2009). Acta Cryst. D65, 148-155.]); software used to prepare material for publication: WinGX publication routines (Farrugia, 1999[Farrugia, L. J. (1999). J. Appl. Cryst. 32, 837-838.]) and PLATON.

Supporting information


Comment top

In continuation to synthesizing the tin complexes containing piperazine (Zia-ur-Rahman et al., 2006, 2007), the title compound (I), (Fig 1) has been obtained as a byproduct.

The crystal structures of (II) 4-nitrophenylpiperazinium chloride monohydrate (Lu, 2007) and 4-(2-pyridyl)piperazin-1-ium chloride (Sadiq-ur-Rehman et al., 2007) has been reported. The title compound have a replacement of nitro group in (II) with methoxy at the same position. Due to this change it is observed that (I) does not contain water molecule although the aquas medium was present during crystallization. In the title compound the benzene ring A(C1—C6) is planar along with the methoxy group. The piperazinium is in chair form with the basal plane B(C8—C11) and the N–atoms are at a distance of 0.6680 (37) and -0.6620 (46) Å. The dihedral angle between the groups A and B is 39.20 (8)°. The molecules are linked each other through intra and intermolecular H–bonding (Table 1, Fig 2). There exists a π interaction between the C3–H3 and the centroid of the benzene ring.

Related literature top

For the synthesis of tin complexes containing piperazine, see: Zia-ur-Rahman et al. (2006, 2007). For related structures, see: Lu (2007); Sadiq-ur-Rehman et al. (2007). CgA is the centroid of the benzene ring.

Experimental top

Me2SnCl2 (0.24 g, 1.08 mmol) in methanol (30 ml) was added dropwise to 4-(4-methoxyphenyl)piperazinium 4-(4-methoxyphenyl)piperazine-1-carbodithioate (0.5 g, 1.08 mmol) in methanol (30 ml) and the mixture was refluxed for 3 h with constant stirring. The 4-(4-methoxyphenyl)piperazinium chloride thus formed, was filtered off and recrystallized from water-ethanol (1:4) to give colourless crystals.

Refinement top

All H atoms were positioned geometrically and refined using a riding model, with N–H = 0.90Å and with Uiso(H) = 1.2Ueq(C), and with C–H = 0.93–0.97Å and with Uiso(H) = 1.2Ueq(C) [C–H = 0.96Å and Uiso(H) = 1.5Ueq(C) for the methyl group].

Computing details top

Data collection: APEX2 (Bruker, 2007); cell refinement: SAINT (Bruker, 2007); data reduction: SAINT (Bruker, 2007); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: ORTEP-3 for Windows (Farrugia, 1997) and PLATON (Spek, 2009); software used to prepare material for publication: WinGX publication routines (Farrugia, 1999) and PLATON (Spek, 2009).

Figures top
[Figure 1] Fig. 1. ORTEP drawing of the title compound, with the atom numbering scheme. The thermal ellipsoids are drawn at the 50% probability level. H-atoms are shown by small circles of arbitrary radii.
[Figure 2] Fig. 2. The partial packing figure (PLATON: Spek, 2009) which shows the dimeric nature of the compound.
4-(4-Methoxyphenyl)piperazin-1-ium chloride top
Crystal data top
C11H17N2O+·ClF(000) = 976
Mr = 228.72Dx = 1.234 Mg m3
Orthorhombic, Iba2Mo Kα radiation, λ = 0.71073 Å
Hall symbol: I 2 -2cCell parameters from 3073 reflections
a = 10.2890 (7) Åθ = 1.2–30.5°
b = 31.5218 (18) ŵ = 0.29 mm1
c = 7.5909 (5) ÅT = 296 K
V = 2461.9 (3) Å3Prismatic, colourless
Z = 80.28 × 0.22 × 0.15 mm
Data collection top
Bruker KAPPA APEXII CCD
diffractometer
3073 independent reflections
Radiation source: fine-focus sealed tube2327 reflections with I > 2σ(I)
Graphite monochromatorRint = 0.026
Detector resolution: 7.3 pixels mm-1θmax = 30.5°, θmin = 1.3°
ω scansh = 1412
Absorption correction: multi-scan
(SADABS; Bruker, 2005)
k = 4244
Tmin = 0.922, Tmax = 0.950l = 510
7605 measured reflections
Refinement top
Refinement on F2Hydrogen site location: inferred from neighbouring sites
Least-squares matrix: fullH-atom parameters constrained
R[F2 > 2σ(F2)] = 0.044 w = 1/[σ2(Fo2) + (0.0883P)2 + 0.0737P]
where P = (Fo2 + 2Fc2)/3
wR(F2) = 0.139(Δ/σ)max < 0.001
S = 1.01Δρmax = 0.35 e Å3
3073 reflectionsΔρmin = 0.29 e Å3
137 parametersExtinction correction: SHELXL, Fc*=kFc[1+0.001xFc2λ3/sin(2θ)]-1/4
1 restraintExtinction coefficient: 0.0136 (13)
Primary atom site location: structure-invariant direct methodsAbsolute structure: Flack (1983), 1076 Friedel pairs
Secondary atom site location: difference Fourier mapAbsolute structure parameter: 0.05 (9)
Crystal data top
C11H17N2O+·ClV = 2461.9 (3) Å3
Mr = 228.72Z = 8
Orthorhombic, Iba2Mo Kα radiation
a = 10.2890 (7) ŵ = 0.29 mm1
b = 31.5218 (18) ÅT = 296 K
c = 7.5909 (5) Å0.28 × 0.22 × 0.15 mm
Data collection top
Bruker KAPPA APEXII CCD
diffractometer
3073 independent reflections
Absorption correction: multi-scan
(SADABS; Bruker, 2005)
2327 reflections with I > 2σ(I)
Tmin = 0.922, Tmax = 0.950Rint = 0.026
7605 measured reflections
Refinement top
R[F2 > 2σ(F2)] = 0.044H-atom parameters constrained
wR(F2) = 0.139Δρmax = 0.35 e Å3
S = 1.01Δρmin = 0.29 e Å3
3073 reflectionsAbsolute structure: Flack (1983), 1076 Friedel pairs
137 parametersAbsolute structure parameter: 0.05 (9)
1 restraint
Special details top

Geometry. Bond distances, angles etc. have been calculated using the rounded fractional coordinates. All su's are estimated from the variances of the (full) variance-covariance matrix. The cell e.s.d.'s are taken into account in the estimation of distances, angles and torsion angles

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
O10.41690 (13)0.30736 (4)0.7357 (3)0.0454 (4)
N10.30676 (15)0.13295 (5)0.7320 (3)0.0407 (5)
N20.25384 (18)0.04631 (6)0.6512 (4)0.0561 (8)
C10.33328 (16)0.17757 (5)0.7214 (3)0.0334 (5)
C20.25085 (17)0.20603 (6)0.6364 (3)0.0368 (6)
C30.27578 (17)0.24960 (7)0.6389 (3)0.0362 (6)
C40.38456 (16)0.26505 (6)0.7235 (3)0.0329 (5)
C50.46885 (18)0.23669 (6)0.8075 (3)0.0371 (5)
C60.44271 (18)0.19397 (6)0.8060 (3)0.0386 (6)
C70.3309 (3)0.33675 (8)0.6540 (4)0.0641 (9)
C80.1772 (2)0.11964 (7)0.6751 (3)0.0486 (7)
C90.1533 (2)0.07386 (7)0.7291 (4)0.0563 (7)
C100.3855 (3)0.06000 (7)0.7054 (4)0.0617 (9)
C110.4071 (2)0.10588 (7)0.6540 (4)0.0513 (7)
Cl10.24567 (7)0.04913 (2)0.23863 (13)0.0710 (3)
H20.178150.195870.577010.0442*
H2A0.240590.019350.685850.0673*
H2B0.247700.047180.532990.0673*
H30.218880.268230.583420.0435*
H50.542650.246780.864510.0446*
H60.499370.175490.862770.0464*
H7A0.362810.365070.671130.0962*
H7B0.325770.330800.530140.0962*
H7C0.246050.334210.705560.0962*
H8A0.112080.137830.728280.0583*
H8B0.170190.122260.548110.0583*
H9A0.068040.064930.689060.0675*
H9B0.155570.071510.856490.0675*
H10A0.394860.056910.831950.0742*
H10B0.450210.042220.648930.0742*
H11A0.404740.108520.526700.0615*
H11B0.492120.115030.694200.0615*
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
O10.0468 (7)0.0384 (7)0.0510 (9)0.0060 (5)0.0035 (8)0.0000 (8)
N10.0415 (8)0.0359 (7)0.0447 (9)0.0009 (6)0.0001 (9)0.0004 (8)
N20.0814 (15)0.0327 (10)0.0542 (14)0.0018 (8)0.0042 (10)0.0048 (9)
C10.0351 (8)0.0346 (8)0.0306 (9)0.0019 (6)0.0006 (9)0.0009 (8)
C20.0353 (9)0.0401 (10)0.0351 (11)0.0007 (7)0.0065 (8)0.0002 (8)
C30.0345 (9)0.0382 (10)0.0359 (10)0.0024 (7)0.0041 (8)0.0011 (8)
C40.0340 (8)0.0373 (8)0.0273 (8)0.0021 (6)0.0038 (8)0.0019 (8)
C50.0320 (8)0.0467 (10)0.0327 (9)0.0036 (8)0.0052 (8)0.0020 (8)
C60.0352 (9)0.0458 (10)0.0349 (10)0.0064 (8)0.0030 (8)0.0038 (8)
C70.0701 (16)0.0391 (12)0.083 (2)0.0030 (11)0.0173 (15)0.0059 (12)
C80.0468 (11)0.0391 (11)0.0599 (16)0.0038 (9)0.0042 (10)0.0035 (9)
C90.0571 (12)0.0463 (11)0.0654 (15)0.0088 (9)0.0005 (14)0.0007 (13)
C100.0658 (14)0.0392 (11)0.080 (2)0.0088 (10)0.0024 (14)0.0063 (12)
C110.0502 (12)0.0381 (10)0.0655 (15)0.0066 (9)0.0077 (11)0.0001 (10)
Cl10.1167 (6)0.0368 (3)0.0596 (4)0.0072 (3)0.0038 (4)0.0031 (3)
Geometric parameters (Å, º) top
O1—C41.378 (2)C10—C111.514 (3)
O1—C71.423 (3)C2—H20.9300
N1—C11.435 (2)C3—H30.9300
N1—C81.463 (3)C5—H50.9300
N1—C111.464 (3)C6—H60.9300
N2—C91.474 (3)C7—H7A0.9600
N2—C101.480 (4)C7—H7B0.9600
N2—H2A0.9000C7—H7C0.9600
N2—H2B0.9000C8—H8A0.9700
C1—C21.393 (3)C8—H8B0.9700
C1—C61.396 (3)C9—H9A0.9700
C2—C31.397 (3)C9—H9B0.9700
C3—C41.379 (3)C10—H10A0.9700
C4—C51.399 (3)C10—H10B0.9700
C5—C61.373 (3)C11—H11A0.9700
C8—C91.520 (3)C11—H11B0.9700
Cl1···N23.134 (3)H2···H8A2.2600
Cl1···N2i3.082 (2)H2···H8B2.3300
Cl1···H2Ai2.2000H2A···Cl1vi2.2000
Cl1···H9Bii3.1300H2B···H11A2.5200
Cl1···H2B2.2400H2B···Cl12.2400
Cl1···H7Aiii2.9700H2B···H8B2.5000
O1···H2iv2.7700H3···C5iii2.8500
O1···H8Av2.6500H3···C72.5100
N1···N22.852 (3)H3···H7B2.2900
N2···N12.852 (3)H3···H7C2.2900
N2···Cl13.134 (3)H3···C6iii2.9400
N2···Cl1vi3.082 (2)H3···C5vii3.0900
N1···H7Biv2.8800H5···C3ix2.8000
C2···C4iii3.549 (3)H5···C3v2.9500
C3···C5vii3.435 (3)H5···C4ix2.8800
C3···C5iii3.585 (3)H6···C112.8700
C3···C4iii3.589 (3)H6···H11B2.3000
C4···C2iv3.549 (3)H7A···Cl1iv2.9700
C4···C3iv3.589 (3)H7B···C32.7400
C5···C3v3.435 (3)H7B···C1iii2.8700
C5···C3iv3.585 (3)H7B···H32.2900
C1···H7Biv2.8700H7B···N1iii2.8800
C2···H8A2.6700H7B···H8Aiii2.5800
C2···H8B2.8500H7C···H32.2900
C3···H5viii2.8000H7C···C32.7300
C3···H5vii2.9500H8A···C22.6700
C3···H7C2.7300H8A···H7Biv2.5800
C3···H7B2.7400H8A···O1vii2.6500
C4···H2iv3.0200H8A···H22.2600
C4···H5viii2.8800H8A···C7vii3.0500
C5···H3v3.0900H8B···H2B2.5000
C5···H3iv2.8500H8B···H11A2.4600
C6···H11B2.6800H8B···C22.8500
C6···H3iv2.9400H8B···H22.3300
C7···H8Av3.0500H9B···Cl1x3.1300
C7···H32.5100H9B···H10A2.5100
C8···H22.5200H10A···H9B2.5100
C11···H62.8700H11A···H2B2.5200
H2···C82.5200H11A···H8B2.4600
H2···C4iii3.0200H11B···H62.3000
H2···O1iii2.7700H11B···C62.6800
C4—O1—C7116.79 (18)C6—C5—H5120.00
C1—N1—C8115.97 (16)C1—C6—H6119.00
C1—N1—C11114.48 (16)C5—C6—H6119.00
C8—N1—C11110.85 (17)O1—C7—H7A109.00
C9—N2—C10111.0 (2)O1—C7—H7B109.00
C9—N2—H2B109.00O1—C7—H7C109.00
C10—N2—H2A109.00H7A—C7—H7B109.00
C10—N2—H2B109.00H7A—C7—H7C109.00
H2A—N2—H2B108.00H7B—C7—H7C109.00
C9—N2—H2A109.00N1—C8—H8A110.00
N1—C1—C2122.78 (16)N1—C8—H8B110.00
N1—C1—C6119.39 (17)C9—C8—H8A110.00
C2—C1—C6117.76 (16)C9—C8—H8B110.00
C1—C2—C3120.99 (17)H8A—C8—H8B108.00
C2—C3—C4120.16 (18)N2—C9—H9A110.00
O1—C4—C5115.99 (17)N2—C9—H9B110.00
O1—C4—C3124.69 (18)C8—C9—H9A110.00
C3—C4—C5119.31 (18)C8—C9—H9B110.00
C4—C5—C6120.09 (18)H9A—C9—H9B108.00
C1—C6—C5121.68 (18)N2—C10—H10A110.00
N1—C8—C9109.88 (17)N2—C10—H10B110.00
N2—C9—C8109.72 (19)C11—C10—H10A110.00
N2—C10—C11110.0 (2)C11—C10—H10B110.00
N1—C11—C10110.4 (2)H10A—C10—H10B108.00
C1—C2—H2119.00N1—C11—H11A110.00
C3—C2—H2120.00N1—C11—H11B110.00
C2—C3—H3120.00C10—C11—H11A110.00
C4—C3—H3120.00C10—C11—H11B110.00
C4—C5—H5120.00H11A—C11—H11B108.00
C7—O1—C4—C30.2 (3)N1—C1—C2—C3175.8 (2)
C7—O1—C4—C5178.8 (2)C6—C1—C2—C31.2 (3)
C8—N1—C1—C210.2 (3)N1—C1—C6—C5176.6 (2)
C8—N1—C1—C6166.8 (2)C2—C1—C6—C50.5 (3)
C11—N1—C1—C2120.9 (2)C1—C2—C3—C41.2 (3)
C11—N1—C1—C662.2 (3)C2—C3—C4—O1179.0 (2)
C1—N1—C8—C9168.1 (2)C2—C3—C4—C50.4 (3)
C11—N1—C8—C959.1 (3)O1—C4—C5—C6178.4 (2)
C1—N1—C11—C10167.9 (2)C3—C4—C5—C60.3 (3)
C8—N1—C11—C1058.6 (3)C4—C5—C6—C10.3 (3)
C10—N2—C9—C857.6 (3)N1—C8—C9—N258.2 (3)
C9—N2—C10—C1156.9 (3)N2—C10—C11—N156.8 (3)
Symmetry codes: (i) x, y, z1/2; (ii) x, y, z1; (iii) x+1/2, y+1/2, z1/2; (iv) x+1/2, y+1/2, z+1/2; (v) x+1/2, y+1/2, z; (vi) x, y, z+1/2; (vii) x1/2, y+1/2, z; (viii) x+1, y, z1/2; (ix) x+1, y, z+1/2; (x) x, y, z+1.
Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
N2—H2A···Cl1vi0.902.203.082 (2)168
N2—H2B···Cl10.902.243.134 (3)177
C3—H3···CgAiii0.932.883.573 (2)133
Symmetry codes: (iii) x+1/2, y+1/2, z1/2; (vi) x, y, z+1/2.

Experimental details

Crystal data
Chemical formulaC11H17N2O+·Cl
Mr228.72
Crystal system, space groupOrthorhombic, Iba2
Temperature (K)296
a, b, c (Å)10.2890 (7), 31.5218 (18), 7.5909 (5)
V3)2461.9 (3)
Z8
Radiation typeMo Kα
µ (mm1)0.29
Crystal size (mm)0.28 × 0.22 × 0.15
Data collection
DiffractometerBruker KAPPA APEXII CCD
diffractometer
Absorption correctionMulti-scan
(SADABS; Bruker, 2005)
Tmin, Tmax0.922, 0.950
No. of measured, independent and
observed [I > 2σ(I)] reflections
7605, 3073, 2327
Rint0.026
(sin θ/λ)max1)0.713
Refinement
R[F2 > 2σ(F2)], wR(F2), S 0.044, 0.139, 1.01
No. of reflections3073
No. of parameters137
No. of restraints1
H-atom treatmentH-atom parameters constrained
Δρmax, Δρmin (e Å3)0.35, 0.29
Absolute structureFlack (1983), 1076 Friedel pairs
Absolute structure parameter0.05 (9)

Computer programs: APEX2 (Bruker, 2007), SAINT (Bruker, 2007), SHELXS97 (Sheldrick, 2008), SHELXL97 (Sheldrick, 2008), ORTEP-3 for Windows (Farrugia, 1997) and PLATON (Spek, 2009), WinGX publication routines (Farrugia, 1999) and PLATON (Spek, 2009).

Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
N2—H2A···Cl1i0.902.203.082 (2)168
N2—H2B···Cl10.902.243.134 (3)177
C3—H3···CgAii0.932.883.573 (2)133
Symmetry codes: (i) x, y, z+1/2; (ii) x+1/2, y+1/2, z1/2.
 

Acknowledgements

The authors acknowledge the the Higher Education Commission, Islamabad, Pakistan, for funding the purchase of the diffractometer at GCU, Lahore.

References

First citationBruker (2005). SADABS. Bruker AXS Inc. Madison, Wisconsin, USA.  Google Scholar
First citationBruker (2007). APEX2 and SAINT. Bruker AXS Inc. Madison, Wisconsin, USA.  Google Scholar
First citationFarrugia, L. J. (1997). J. Appl. Cryst. 30, 565.  CrossRef IUCr Journals Google Scholar
First citationFarrugia, L. J. (1999). J. Appl. Cryst. 32, 837–838.  CrossRef CAS IUCr Journals Google Scholar
First citationFlack, H. D. (1983). Acta Cryst. A39, 876–881.  CrossRef CAS Web of Science IUCr Journals Google Scholar
First citationLu, Y.-X. (2007). Acta Cryst. E63, o3611.  Web of Science CSD CrossRef IUCr Journals Google Scholar
First citationSadiq-ur-Rehman, Saeed, S., Ali, S., Shahzadi, S. & Helliwell, M. (2007). Acta Cryst. E63, o4526.  Web of Science CSD CrossRef IUCr Journals 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 citationZia-ur-Rahman, Ali, S., Muhammad, N. & Meetsma, A. (2006). Acta Cryst. E62, m3560–m3561.  Web of Science CSD CrossRef IUCr Journals Google Scholar
First citationZia-ur-Rahman, Ali, S., Muhammed, N. & Meetsma, A. (2007). Acta Cryst. E63, m89–m90.  Web of Science CSD CrossRef 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.

Journal logoCRYSTALLOGRAPHIC
COMMUNICATIONS
ISSN: 2056-9890
Follow Acta Cryst. E
Sign up for e-alerts
Follow Acta Cryst. on Twitter
Follow us on facebook
Sign up for RSS feeds