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Acta Crystallographica Section E: Structure Reports Online logoLink to Acta Crystallographica Section E: Structure Reports Online
. 2011 Aug 27;67(Pt 9):m1282. doi: 10.1107/S1600536811032351

8-Hy­droxy-2-methyl­quinolinium diiodido(2-methyl­quinolin-8-olato-κ2 N,O)zincate

Ezzatollah Najafi a, Mostafa M Amini a, Seik Weng Ng b,c,*
PMCID: PMC3200965  PMID: 22064767

Abstract

The reaction of 2-methyl-8-hy­droxy­quinoline and zinc iodide in acetonitrile affords the title salt, (C10H10NO)[Zn(C10H8NO)I2], in which the ZnII ion is coordinated by a N,O-chelating 2-methyl­quinolin-8-olate ligand and two iodide ligands in a distorted tetra­hedral geometry. The cation is linked to the anion by an O—H⋯O hydrogen bond.

Related literature

For the crystal structures of two related 8-hy­droxy-2-methyl­quinolinium dihalo(2-methyl­quinolin-8-olato)zincate aceto­nitrile solvates, see: Najafi et al. (2011a ▶,b ▶). For the crystal structures of related methanol solvates, see: Najafi et al. (2010a ▶,b ▶); Sattarzadeh et al. (2009 ▶).graphic file with name e-67-m1282-scheme1.jpg

Experimental

Crystal data

  • (C10H10NO)[Zn(C10H8NO)I2]

  • M r = 637.53

  • Monoclinic, Inline graphic

  • a = 8.1794 (2) Å

  • b = 13.9441 (3) Å

  • c = 9.1838 (2) Å

  • β = 102.503 (3)°

  • V = 1022.61 (4) Å3

  • Z = 2

  • Mo Kα radiation

  • μ = 4.24 mm−1

  • T = 100 K

  • 0.40 × 0.30 × 0.20 mm

Data collection

  • Agilent SuperNova Dual diffractometer with an Atlas detector

  • Absorption correction: multi-scan (CrysAlis PRO; Agilent, 2010 ▶) T min = 0.282, T max = 0.485

  • 4995 measured reflections

  • 3765 independent reflections

  • 3692 reflections with I > 2σ(I)

  • R int = 0.025

Refinement

  • R[F 2 > 2σ(F 2)] = 0.034

  • wR(F 2) = 0.087

  • S = 1.04

  • 3765 reflections

  • 247 parameters

  • 1 restraint

  • H-atom parameters constrained

  • Δρmax = 0.99 e Å−3

  • Δρmin = −1.53 e Å−3

  • Absolute structure: Flack (1983 ▶) 1389 Friedel pairs

  • Flack parameter: 0.01 (2)

Data collection: CrysAlis PRO (Agilent, 2010 ▶); cell refinement: CrysAlis PRO; data reduction: CrysAlis PRO; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 ▶); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 ▶); molecular graphics: X-SEED (Barbour, 2001 ▶); software used to prepare material for publication: publCIF (Westrip, 2010 ▶).

Supplementary Material

Crystal structure: contains datablock(s) global, I. DOI: 10.1107/S1600536811032351/lh5307sup1.cif

e-67-m1282-sup1.cif (19.6KB, cif)

Structure factors: contains datablock(s) I. DOI: 10.1107/S1600536811032351/lh5307Isup2.hkl

e-67-m1282-Isup2.hkl (184.6KB, hkl)

Additional supplementary materials: crystallographic information; 3D view; checkCIF report

Table 1. Hydrogen-bond geometry (Å, °).

D—H⋯A D—H H⋯A D⋯A D—H⋯A
O2—H2o⋯O1 0.84 1.71 2.542 (6) 170
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Acknowledgments

We thank Shahid Beheshti University and the University of Malaya for supporting this study.

supplementary crystallographic information

Comment

We have synthesized methanol-solvated 8-hydroxy-2-methylquinolinium dihalo(2-methylquinolin-8-olato)zincates(II) by the direct reaction of the zinc halide and 8-hydroxy-2-methylquinolin in methanol. The salts have the ZnII atom in a tetrahedral geometry, and the ion-pairs are linked to the solvent molecules by hydrogen bonds (Najafi et al., 2010a; Najafi et al., 2010b; Sattarzadeh et al., 2009). These studies have been extended to the use of acetonitrile as a solvent. In a previous study, the reaction of zinc chloride/bromide and the quinoline in acetonitrile yielded the disolvated/monosolvated salts (Najafi et al., 2011a, 2011b). In the present study, using zinc iodide gave a solvent-free (Fig. 1) crystal structure. In (C10H10NO)[ZnI2(C10H8NO)], the metal in the anion is N,O-chelated by the deprotonated ligand and it exists in a distorted tetrahedral geometry. The cation is linked to the anion by an O–H···O hydrogen bond (Table 1).

Experimental

Zinc iodide (0.32 g, 0.75 mmol) and 2-methyl-8-hydroxyquinoline (0.24 g, 1.5 mmol) were loaded into a convection tube and the tube was filled with acetonitrile and kept at 333 K. Yellow crystals were collected from the side arm after several days.

Refinement

Carbon-bound H-atoms were placed in calculated positions [C—H 0.95 to 0.98 Å, Uiso(H) 1.2 to 1.5Ueq(C)] and were included in the refinement in the riding model approximation. The N and O bound H atoms were similarly treated [N–H 0.88, O–H 0.84 Å; Uiso(H) = 1.2Ueq(N) or 1.5Ueq(O) ]. The (-2 8 1), (-2 3 5), (-2 2 5), (-2 4 5) and (-2 5 5) reflections were removed.

Figures

Fig. 1.

Fig. 1.

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Thermal ellipsoid plot (Barbour, 2001) of (C10H10NO)[ZnI2(C10H8NO)] at the 70% probability level. Hydrogen atoms are drawn as spheres of arbitrary radius.

Crystal data

(C10H10NO)[Zn(C10H8NO)I2] F(000) = 608
Mr = 637.53 Dx = 2.070 Mg m−3
Monoclinic, P21 Mo Kα radiation, λ = 0.71073 Å
Hall symbol: P 2yb Cell parameters from 4585 reflections
a = 8.1794 (2) Å θ = 2.6–26.3°
b = 13.9441 (3) Å µ = 4.24 mm−1
c = 9.1838 (2) Å T = 100 K
β = 102.503 (3)° Block, yellow
V = 1022.61 (4) Å3 0.40 × 0.30 × 0.20 mm
Z = 2
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Data collection

Agilent SuperNova Dual diffractometer with an Atlas detector 3765 independent reflections
Radiation source: SuperNova (Mo) X-ray Source 3692 reflections with I > 2σ(I)
Mirror Rint = 0.025
Detector resolution: 10.4041 pixels mm-1 θmax = 27.5°, θmin = 2.6°
ω scans h = −10→10
Absorption correction: multi-scan (CrysAlis PRO; Agilent, 2010) k = −17→18
Tmin = 0.282, Tmax = 0.485 l = −11→7
4995 measured reflections
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Refinement

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)] = 0.034 H-atom parameters constrained
wR(F2) = 0.087 w = 1/[σ2(Fo2) + (0.0676P)2 + 0.3294P] where P = (Fo2 + 2Fc2)/3
S = 1.04 (Δ/σ)max = 0.001
3765 reflections Δρmax = 0.99 e Å−3
247 parameters Δρmin = −1.53 e Å−3
1 restraint Absolute structure: Flack (1983) 1389 Friedel pairs
Primary atom site location: structure-invariant direct methods Flack parameter: 0.01 (2)
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Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2)

x y z Uiso*/Ueq
I1 0.34742 (4) 0.50002 (2) 0.27609 (4) 0.01513 (10)
I2 0.86547 (4) 0.57723 (3) 0.30050 (4) 0.01526 (10)
Zn1 0.65211 (7) 0.50245 (5) 0.42920 (6) 0.01153 (14)
O1 0.7152 (5) 0.3768 (3) 0.5317 (4) 0.0140 (8)
O2 0.7800 (6) 0.2102 (3) 0.4468 (5) 0.0185 (9)
H2O 0.7556 0.2669 0.4645 0.028*
N1 0.6329 (6) 0.5443 (4) 0.6384 (6) 0.0128 (10)
N2 0.8374 (6) 0.0372 (4) 0.3439 (6) 0.0124 (10)
H2N 0.7921 0.0452 0.4217 0.015*
C1 0.6269 (7) 0.4639 (5) 0.7234 (7) 0.0118 (12)
C2 0.6735 (7) 0.3762 (5) 0.6652 (6) 0.0127 (11)
C3 0.6735 (8) 0.2940 (5) 0.7488 (7) 0.0164 (12)
H3 0.7045 0.2344 0.7126 0.020*
C4 0.6277 (7) 0.2983 (5) 0.8879 (7) 0.0180 (12)
H4 0.6277 0.2407 0.9431 0.022*
C5 0.5831 (8) 0.3824 (5) 0.9472 (7) 0.0176 (12)
H5 0.5521 0.3831 1.0411 0.021*
C6 0.5844 (7) 0.4686 (5) 0.8641 (7) 0.0134 (12)
C7 0.5476 (7) 0.5605 (5) 0.9138 (6) 0.0163 (14)
H7 0.5153 0.5670 1.0067 0.020*
C8 0.5583 (8) 0.6396 (5) 0.8297 (7) 0.0156 (12)
H8 0.5373 0.7014 0.8654 0.019*
C9 0.6008 (8) 0.6297 (5) 0.6886 (7) 0.0134 (13)
C10 0.6195 (8) 0.7153 (4) 0.5938 (7) 0.0160 (12)
H10A 0.5744 0.7723 0.6337 0.024*
H10B 0.5580 0.7040 0.4912 0.024*
H10C 0.7383 0.7254 0.5947 0.024*
C11 0.8860 (8) 0.1179 (5) 0.2762 (7) 0.0137 (12)
C12 0.8575 (8) 0.2094 (5) 0.3348 (8) 0.0144 (12)
C13 0.9136 (8) 0.2891 (4) 0.2680 (7) 0.0164 (12)
H13 0.8988 0.3516 0.3043 0.020*
C14 0.9923 (8) 0.2774 (5) 0.1470 (7) 0.0190 (13)
H14 1.0315 0.3328 0.1049 0.023*
C15 1.0147 (8) 0.1899 (5) 0.0878 (7) 0.0179 (12)
H15 1.0655 0.1847 0.0044 0.021*
C16 0.9607 (8) 0.1066 (4) 0.1530 (7) 0.0133 (12)
C17 0.9785 (8) 0.0115 (5) 0.1023 (7) 0.0172 (12)
H17 1.0273 0.0012 0.0187 0.021*
C18 0.9261 (8) −0.0647 (4) 0.1728 (7) 0.0156 (12)
H18 0.9374 −0.1278 0.1372 0.019*
C19 0.8552 (7) −0.0510 (6) 0.2982 (7) 0.0130 (15)
C20 0.8021 (8) −0.1330 (5) 0.3803 (7) 0.0187 (12)
H20A 0.7757 −0.1098 0.4733 0.028*
H20B 0.8930 −0.1800 0.4033 0.028*
H20C 0.7027 −0.1631 0.3186 0.028*
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Atomic displacement parameters (Å2)

U11 U22 U33 U12 U13 U23
I1 0.01258 (17) 0.01704 (18) 0.01573 (17) −0.00109 (15) 0.00297 (12) 0.00069 (15)
I2 0.01426 (17) 0.01766 (18) 0.01540 (17) −0.00195 (15) 0.00660 (12) 0.00132 (15)
Zn1 0.0134 (3) 0.0116 (3) 0.0105 (3) 0.0006 (3) 0.0048 (2) 0.0002 (3)
O1 0.021 (2) 0.0107 (18) 0.012 (2) 0.0033 (17) 0.0093 (16) 0.0002 (16)
O2 0.025 (2) 0.0118 (19) 0.022 (2) 0.0044 (18) 0.0115 (18) −0.0004 (17)
N1 0.012 (2) 0.014 (2) 0.013 (2) −0.001 (2) 0.0035 (18) 0.003 (2)
N2 0.013 (2) 0.013 (2) 0.012 (2) 0.003 (2) 0.0051 (19) −0.001 (2)
C1 0.010 (3) 0.013 (3) 0.012 (3) −0.001 (2) 0.002 (2) 0.001 (2)
C2 0.011 (3) 0.017 (3) 0.010 (3) −0.002 (2) 0.003 (2) 0.000 (2)
C3 0.017 (3) 0.011 (3) 0.020 (3) 0.002 (2) 0.003 (2) 0.000 (2)
C4 0.019 (3) 0.016 (3) 0.019 (3) −0.001 (3) 0.006 (2) 0.008 (2)
C5 0.021 (3) 0.021 (3) 0.013 (3) −0.005 (3) 0.007 (2) 0.000 (2)
C6 0.012 (3) 0.013 (3) 0.015 (3) −0.001 (2) 0.002 (2) 0.000 (2)
C7 0.020 (3) 0.022 (4) 0.008 (3) 0.001 (3) 0.005 (2) −0.003 (2)
C8 0.018 (3) 0.012 (3) 0.017 (3) −0.002 (2) 0.004 (2) −0.004 (2)
C9 0.012 (3) 0.012 (3) 0.016 (3) 0.007 (3) 0.004 (2) 0.003 (2)
C10 0.017 (3) 0.013 (3) 0.018 (3) 0.003 (2) 0.004 (2) 0.001 (2)
C11 0.012 (3) 0.013 (3) 0.016 (3) 0.003 (2) 0.002 (2) 0.000 (2)
C12 0.012 (3) 0.015 (3) 0.014 (3) 0.001 (2) −0.001 (2) −0.002 (2)
C13 0.019 (3) 0.013 (3) 0.017 (3) −0.001 (2) 0.005 (2) 0.001 (2)
C14 0.021 (3) 0.018 (3) 0.019 (3) −0.002 (2) 0.004 (2) 0.001 (2)
C15 0.018 (3) 0.023 (3) 0.014 (3) −0.001 (3) 0.008 (2) 0.001 (2)
C16 0.011 (2) 0.013 (3) 0.015 (3) 0.003 (2) 0.002 (2) −0.001 (2)
C17 0.014 (3) 0.020 (3) 0.018 (3) 0.003 (3) 0.005 (2) −0.006 (3)
C18 0.019 (3) 0.011 (3) 0.016 (3) 0.006 (2) 0.005 (2) −0.004 (2)
C19 0.016 (3) 0.013 (3) 0.010 (3) 0.003 (2) 0.002 (2) −0.001 (2)
C20 0.022 (3) 0.016 (3) 0.019 (3) −0.001 (2) 0.006 (2) −0.001 (2)
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Geometric parameters (Å, °)

I1—Zn1 2.5831 (7) C8—C9 1.420 (9)
I2—Zn1 2.5343 (7) C8—H8 0.9500
Zn1—O1 2.003 (4) C9—C10 1.505 (9)
Zn1—N1 2.046 (5) C10—H10A 0.9800
O1—C2 1.342 (7) C10—H10B 0.9800
O2—C12 1.320 (8) C10—H10C 0.9800
O2—H2O 0.8400 C11—C16 1.406 (9)
N1—C9 1.323 (8) C11—C12 1.423 (9)
N1—C1 1.373 (8) C12—C13 1.394 (9)
N2—C19 1.317 (9) C13—C14 1.409 (8)
N2—C11 1.386 (8) C13—H13 0.9500
N2—H2N 0.8800 C14—C15 1.365 (9)
C1—C6 1.410 (9) C14—H14 0.9500
C1—C2 1.420 (9) C15—C16 1.420 (9)
C2—C3 1.380 (9) C15—H15 0.9500
C3—C4 1.407 (8) C16—C17 1.423 (9)
C3—H3 0.9500 C17—C18 1.362 (9)
C4—C5 1.376 (9) C17—H17 0.9500
C4—H4 0.9500 C18—C19 1.409 (8)
C5—C6 1.424 (9) C18—H18 0.9500
C5—H5 0.9500 C19—C20 1.486 (9)
C6—C7 1.415 (9) C20—H20A 0.9800
C7—C8 1.360 (9) C20—H20B 0.9800
C7—H7 0.9500 C20—H20C 0.9800
O1—Zn1—N1 82.69 (19) C8—C9—C10 121.8 (6)
O1—Zn1—I2 116.46 (12) C9—C10—H10A 109.5
N1—Zn1—I2 121.41 (14) C9—C10—H10B 109.5
O1—Zn1—I1 111.38 (13) H10A—C10—H10B 109.5
N1—Zn1—I1 104.68 (14) C9—C10—H10C 109.5
I2—Zn1—I1 115.60 (3) H10A—C10—H10C 109.5
C2—O1—Zn1 110.1 (3) H10B—C10—H10C 109.5
C12—O2—H2O 109.5 N2—C11—C16 119.1 (6)
C9—N1—C1 120.2 (5) N2—C11—C12 118.2 (6)
C9—N1—Zn1 130.2 (4) C16—C11—C12 122.7 (6)
C1—N1—Zn1 108.7 (4) O2—C12—C13 126.5 (6)
C19—N2—C11 123.5 (5) O2—C12—C11 116.6 (6)
C19—N2—H2N 118.2 C13—C12—C11 116.8 (6)
C11—N2—H2N 118.2 C12—C13—C14 120.3 (6)
N1—C1—C6 122.0 (6) C12—C13—H13 119.8
N1—C1—C2 116.4 (5) C14—C13—H13 119.8
C6—C1—C2 121.6 (6) C15—C14—C13 122.7 (6)
O1—C2—C3 123.0 (6) C15—C14—H14 118.6
O1—C2—C1 118.7 (5) C13—C14—H14 118.6
C3—C2—C1 118.3 (5) C14—C15—C16 118.9 (5)
C2—C3—C4 120.1 (6) C14—C15—H15 120.6
C2—C3—H3 119.9 C16—C15—H15 120.6
C4—C3—H3 119.9 C11—C16—C15 118.4 (6)
C5—C4—C3 122.8 (5) C11—C16—C17 117.5 (6)
C5—C4—H4 118.6 C15—C16—C17 124.1 (5)
C3—C4—H4 118.6 C18—C17—C16 120.4 (5)
C4—C5—C6 118.3 (5) C18—C17—H17 119.8
C4—C5—H5 120.9 C16—C17—H17 119.8
C6—C5—H5 120.9 C17—C18—C19 120.7 (6)
C1—C6—C7 116.7 (6) C17—C18—H18 119.7
C1—C6—C5 119.0 (6) C19—C18—H18 119.7
C7—C6—C5 124.3 (5) N2—C19—C18 118.8 (6)
C8—C7—C6 120.5 (5) N2—C19—C20 119.4 (5)
C8—C7—H7 119.8 C18—C19—C20 121.8 (6)
C6—C7—H7 119.8 C19—C20—H20A 109.5
C7—C8—C9 119.9 (6) C19—C20—H20B 109.5
C7—C8—H8 120.1 H20A—C20—H20B 109.5
C9—C8—H8 120.1 C19—C20—H20C 109.5
N1—C9—C8 120.8 (6) H20A—C20—H20C 109.5
N1—C9—C10 117.3 (5) H20B—C20—H20C 109.5
N1—Zn1—O1—C2 15.2 (4) C6—C7—C8—C9 2.2 (9)
I2—Zn1—O1—C2 136.8 (3) C1—N1—C9—C8 −0.7 (9)
I1—Zn1—O1—C2 −87.7 (4) Zn1—N1—C9—C8 166.6 (4)
O1—Zn1—N1—C9 175.6 (6) C1—N1—C9—C10 176.5 (5)
I2—Zn1—N1—C9 59.0 (6) Zn1—N1—C9—C10 −16.3 (9)
I1—Zn1—N1—C9 −74.1 (6) C7—C8—C9—N1 −1.0 (9)
O1—Zn1—N1—C1 −15.9 (4) C7—C8—C9—C10 −178.0 (6)
I2—Zn1—N1—C1 −132.6 (3) C19—N2—C11—C16 −0.8 (8)
I1—Zn1—N1—C1 94.3 (4) C19—N2—C11—C12 179.0 (6)
C9—N1—C1—C6 1.1 (9) N2—C11—C12—O2 −2.6 (8)
Zn1—N1—C1—C6 −168.6 (5) C16—C11—C12—O2 177.2 (5)
C9—N1—C1—C2 −176.1 (6) N2—C11—C12—C13 177.6 (5)
Zn1—N1—C1—C2 14.1 (6) C16—C11—C12—C13 −2.6 (9)
Zn1—O1—C2—C3 167.8 (5) O2—C12—C13—C14 −178.9 (6)
Zn1—O1—C2—C1 −12.1 (6) C11—C12—C13—C14 0.9 (9)
N1—C1—C2—O1 −1.7 (8) C12—C13—C14—C15 1.3 (10)
C6—C1—C2—O1 −178.9 (6) C13—C14—C15—C16 −1.7 (9)
N1—C1—C2—C3 178.3 (5) N2—C11—C16—C15 −178.0 (5)
C6—C1—C2—C3 1.1 (9) C12—C11—C16—C15 2.2 (9)
O1—C2—C3—C4 −179.8 (5) N2—C11—C16—C17 1.4 (8)
C1—C2—C3—C4 0.2 (9) C12—C11—C16—C17 −178.4 (6)
C2—C3—C4—C5 −0.6 (10) C14—C15—C16—C11 0.0 (9)
C3—C4—C5—C6 −0.3 (9) C14—C15—C16—C17 −179.4 (6)
N1—C1—C6—C7 0.1 (9) C11—C16—C17—C18 −0.6 (9)
C2—C1—C6—C7 177.1 (5) C15—C16—C17—C18 178.8 (6)
N1—C1—C6—C5 −179.1 (5) C16—C17—C18—C19 −0.8 (9)
C2—C1—C6—C5 −2.0 (9) C11—N2—C19—C18 −0.6 (9)
C4—C5—C6—C1 1.6 (9) C11—N2—C19—C20 178.8 (6)
C4—C5—C6—C7 −177.5 (6) C17—C18—C19—N2 1.4 (9)
C1—C6—C7—C8 −1.7 (9) C17—C18—C19—C20 −178.0 (6)
C5—C6—C7—C8 177.4 (6)
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Hydrogen-bond geometry (Å, °)

D—H···A D—H H···A D···A D—H···A
O2—H2o···O1 0.84 1.71 2.542 (6) 170
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Footnotes

Supplementary data and figures for this paper are available from the IUCr electronic archives (Reference: LH5307).

References

  1. Agilent (2010). CrysAlis PRO Agilent Technologies, Yarnton, England.
  2. Barbour, L. J. (2001). J. Supramol. Chem. 1, 189–191.
  3. Flack, H. D. (1983). Acta Cryst. A39, 876–881.
  4. Najafi, E., Amini, M. M. & Ng, S. W. (2010a). Acta Cryst. E66, m1276. [DOI] [PMC free article] [PubMed]
  5. Najafi, E., Amini, M. M. & Ng, S. W. (2010b). Acta Cryst. E66, m1277. [DOI] [PMC free article] [PubMed]
  6. Najafi, E., Amini, M. M. & Ng, S. W. (2011a). Acta Cryst. E67, m1280. [DOI] [PMC free article] [PubMed]
  7. Najafi, E., Amini, M. M. & Ng, S. W. (2011b). Acta Cryst. E67, m1281. [DOI] [PMC free article] [PubMed]
  8. Sattarzadeh, E., Mohammadnezhad, G., Amini, M. M. & Ng, S. W. (2009). Acta Cryst. E65, m553. [DOI] [PMC free article] [PubMed]
  9. Sheldrick, G. M. (2008). Acta Cryst. A64, 112–122. [DOI] [PubMed]
  10. Westrip, S. P. (2010). J. Appl. Cryst. 43, 920–925.

Associated Data

This section collects any data citations, data availability statements, or supplementary materials included in this article.

Supplementary Materials

Crystal structure: contains datablock(s) global, I. DOI: 10.1107/S1600536811032351/lh5307sup1.cif

e-67-m1282-sup1.cif (19.6KB, cif)

Structure factors: contains datablock(s) I. DOI: 10.1107/S1600536811032351/lh5307Isup2.hkl

e-67-m1282-Isup2.hkl (184.6KB, hkl)

Additional supplementary materials: crystallographic information; 3D view; checkCIF report

Articles from Acta Crystallographica Section E: Structure Reports Online are provided here courtesy of International Union of Crystallography

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