PMCCPMCCPMCC

Search tips
Search criteria 

Advanced

 
Logo of actaeInternational Union of Crystallographysearchopen accessarticle submissionjournal home pagethis article
 
Acta Crystallogr Sect E Struct Rep Online. 2010 July 1; 66(Pt 7): o1522.
Published online 2010 June 5. doi:  10.1107/S1600536810020039
PMCID: PMC3007085

(E)-N′-(4-Nitro­benzyl­idene)-4-(8-quinol­yloxy)butano­hydrazide

Abstract

In the title compound, C20H18N4O4, conformation along the bond sequence linking the benzene and quinoline rings, which have a mean inter­planar dihedral angle of 2.7 (5)°, is trans–(+)gauche–trans–trans–(−)gauche–trans–trans. In the crystal structure, a pair of inter­molecular N—H(...)O hydrogen bonds links the mol­ecules into centrosymmetric cyclic R 2 2(8) dimers, which are aggregated via π–π inter­actions into parallel sheets [quinoline–benzene ring centroid separation = 3.6173 (16)–3.6511 (16) Å]. The sheets are further connected through weak C—H(...)O inter­actions, giving a supra­molecular two-dimensional network.

Related literature

For general background to Schiff bases in coordination chemistry, see: Calligaris & Randaccio (1987 [triangle]). For related structures, see: Zheng, Li et al. (2008 [triangle]); Zheng, Qiu et al. (2006 [triangle]); Zheng, Wu, Lu et al. (2006 [triangle]); Zheng (2006 [triangle]); Zheng, Wu, Li et al. (2006 [triangle], 2007 [triangle]); Xie et al. (2008 [triangle]); Chen & Li (2009 [triangle]); Zhang et al. (2009 [triangle]). For bond-length data, see: Allen et al. (1987 [triangle]). For hydrogen-bond motifs, see: Bernstein et al. (1995 [triangle]).

An external file that holds a picture, illustration, etc.
Object name is e-66-o1522-scheme1.jpg

Experimental

Crystal data

  • C20H18N4O4
  • M r = 378.38
  • Monoclinic, An external file that holds a picture, illustration, etc.
Object name is e-66-o1522-efi1.jpg
  • a = 9.836 (3) Å
  • b = 10.633 (3) Å
  • c = 17.566 (5) Å
  • β = 92.365 (7)°
  • V = 1835.6 (9) Å3
  • Z = 4
  • Mo Kα radiation
  • μ = 0.10 mm−1
  • T = 296 K
  • 0.22 × 0.17 × 0.15 mm

Data collection

  • Bruker SMART CCD area-detector diffractometer
  • Absorption correction: multi-scan (SADABS; Sheldrick, 1996 [triangle]) T min = 0.979, T max = 0.986
  • 9957 measured reflections
  • 3256 independent reflections
  • 2345 reflections with I > 2σ(I)
  • R int = 0.036

Refinement

  • R[F 2 > 2σ(F 2)] = 0.044
  • wR(F 2) = 0.146
  • S = 1.07
  • 3256 reflections
  • 253 parameters
  • H-atom parameters constrained
  • Δρmax = 0.22 e Å−3
  • Δρmin = −0.23 e Å−3

Data collection: SMART (Bruker, 2007 [triangle]); cell refinement: SAINT (Bruker, 2007 [triangle]); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 [triangle]); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 [triangle]); molecular graphics: SHELXTL (Sheldrick, 2008 [triangle]); software used to prepare material for publication: SHELXTL.

Table 1
Hydrogen-bond geometry (Å, °)

Supplementary Material

Crystal structure: contains datablocks global, I. DOI: 10.1107/S1600536810020039/zs2040sup1.cif

Structure factors: contains datablocks I. DOI: 10.1107/S1600536810020039/zs2040Isup2.hkl

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

Acknowledgments

The authors thank the Key Lab of Natural Medicine Research and Development in Jiangxi for financial support.

supplementary crystallographic information

Comment

Schiff bases are one of the most prevalent mixed-donor ligands in the field of coordination chemistry, playing an important role in the development of the chemistry related to catalysis and enzymatic reactions, magnetism, and supramolecular architectures (Calligaris & Randaccio, 1987). Structures of Schiff bases derived from substituted 4-(quinolin-8-yloxy)butanehydrazide and closely related to the title compound have been reported earlier (Zheng, Li et al., 2008; Zheng, Wu, Lu et al., 2006; Zheng, 2006; Zheng, Wu, Li et al., 2006, 2007; Xie et al., 2008; Chen & Li, 2009; Zhang et al., 2009). In this contribution, we present the synthesis and crystal structure of a new ligand C20H18N4O4 (I), which contains oxygen and nitrogen donors and a flexible aliphatic spacer.

In (I) (Fig.1) the asymmetric unit contains a crystallographically independent molecule with a trans-(+)gauche-trans-trans-(-)gauche-trans-trans conformation along the quinoline ring–benzene ring bond sequence [torsion angles (°): C8–O1–C10–C11, 179.83 (18); O1–C10–C11–C12, 65.1 (3); C10–C11–C12–C13, -178.24; C11–C12–C13–N2, 114.1 (2); C12–C13–N2–N3, -0.1 (3); C13–N2–N3–C14, -178.96 (7); N2–N3–C14–C15, -179.17 (16)]. The bond lengths and angles in (I) are in good agreement with the expected values (Allen et al., 1987) and are comparable to those in the related compounds (Zheng, Wu, Lu et al., 2006; Zheng, 2006; Zheng, Wu, Li et al., 2006, 2007; Xie et al., 2008; Chen et al., 2009; Zhang, XiaHou et al., 2009). The C14—N3 and C13—O2 bond lengths [1.269 (3) and 1.235 (2) Å, respectively] indicate the presence of a typical C═N and C═O. The C═N—N angle of 115.79 (18)° is significantly smaller than the ideal value of 120° expected for sp2-hybridized N atoms, probably due to repulsion between the nitrogen lone pairs and the adjacent N atom (Zheng, Qiu et al., 2006). The benzene and quinoline ring systems are close to coplanar [dihedral angle, 2.7 (5)°]. In the crystal structure, intramolecular C—H···N and C—H···O interactions (Table 1, Fig. 1) produce two edge-sharing S(5) ring motifs (Bernstein et al., 1995) and a pair of intermolecular N—H···O hydrogen bonds link the molecules into centrosymmetric cyclic R22(8) dimers (Fig. 2), which are aggregated viaπ–π interactions into parallel sheets [quinoline–benzene ring centroid separation: 3.6173 (16)–3.6511 (16) Å], which are further connected through weak C—H···O interactions, giving a supramolecular two-dimensional network (Fig. 3).

Experimental

Reagents and solvents used were of commercially available quality. The title compound (I) was synthesized according to the method of Zheng, Li et al., 2008. 4-(Quinolin-8-yloxy)butanehydrazide (0.01 mol), p-formylnitrobenzene (0.01 mol), ethanol (40 ml) and some drops of acetic acid were added to a 100 ml flask and refluxed for 6 h. After cooling to room temperature, the solid product was separated by filtration. Yellow single crystals of (I) suitable for the X-ray diffraction study were obtained by slow evaporation of a tetrahydrofuran solution over a period of four days.

Refinement

All H atoms were placed in idealized positions (C—H = 0.93–0.97 Å, N—H = 0.86 Å) and refined as riding atoms with Uiso(H) = 1.2Ueq(C or N).

Figures

Fig. 1.
The molecular structure of (I), with displacement ellipsoids at the 30% probability level. Intramolecular C–H···N and C–H···O interactions are shown as dashed lines.
Fig. 2.
The cyclic hydrogen-bonded dimer with hydrogen bonds shown as dashed lines. H atoms, except for those involved in hydrogen bonds, are not included.
Fig. 3.
Part of the crystal structure showing hydrogen bonds as dashed lines. H atoms, except for those involved in hydrogen bonds, are not included.

Crystal data

C20H18N4O4F(000) = 792
Mr = 378.38Dx = 1.369 Mg m3
Monoclinic, P21/cMo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ybcCell parameters from 3279 reflections
a = 9.836 (3) Åθ = 2.2–27.9°
b = 10.633 (3) ŵ = 0.10 mm1
c = 17.566 (5) ÅT = 296 K
β = 92.365 (7)°Prism, yellow
V = 1835.6 (9) Å30.22 × 0.17 × 0.15 mm
Z = 4

Data collection

Bruker SMART CCD area-detector diffractometer3256 independent reflections
Radiation source: fine-focus sealed tube2345 reflections with I > 2σ(I)
graphiteRint = 0.036
[var phi] and ω scansθmax = 25.0°, θmin = 2.1°
Absorption correction: multi-scan (SADABS; Sheldrick, 1996)h = −7→11
Tmin = 0.979, Tmax = 0.986k = −12→12
9957 measured reflectionsl = −20→20

Refinement

Refinement on F2Primary atom site location: structure-invariant direct methods
Least-squares matrix: fullSecondary atom site location: difference Fourier map
R[F2 > 2σ(F2)] = 0.044Hydrogen site location: inferred from neighbouring sites
wR(F2) = 0.146H-atom parameters constrained
S = 1.07w = 1/[σ2(Fo2) + (0.0719P)2 + 0.3873P] where P = (Fo2 + 2Fc2)/3
3256 reflections(Δ/σ)max < 0.001
253 parametersΔρmax = 0.22 e Å3
0 restraintsΔρmin = −0.22 e Å3

Special details

Geometry. All esds (except the esd in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell esds are taken into account individually in the estimation of esds in distances, angles and torsion angles; correlations between esds in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell esds is used for estimating esds 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)

xyzUiso*/Ueq
O10.75513 (15)0.53054 (15)0.16112 (8)0.0599 (4)
O21.05475 (15)0.89991 (18)0.07985 (10)0.0749 (5)
O30.0388 (2)0.8161 (3)−0.16156 (15)0.1302 (10)
O40.04918 (18)0.6940 (2)−0.06516 (13)0.0903 (6)
N10.50202 (18)0.48897 (16)0.10959 (10)0.0542 (5)
N20.85327 (17)0.90258 (17)0.01739 (10)0.0499 (4)
H2A0.88440.9544−0.01520.060*
N30.71999 (16)0.86354 (16)0.00912 (10)0.0466 (4)
N40.0993 (2)0.7717 (2)−0.10668 (13)0.0710 (6)
C10.3767 (2)0.4663 (2)0.08357 (15)0.0651 (7)
H10.34790.50420.03800.078*
C20.2845 (2)0.3894 (2)0.11982 (17)0.0685 (7)
H20.19620.37930.09980.082*
C30.3263 (2)0.3297 (2)0.18475 (15)0.0642 (7)
H30.26650.27770.20970.077*
C40.4606 (2)0.34635 (18)0.21447 (11)0.0472 (5)
C50.5148 (3)0.2828 (2)0.28008 (12)0.0601 (6)
H50.46080.22710.30630.072*
C60.6447 (3)0.3036 (2)0.30424 (12)0.0605 (6)
H60.67930.26100.34710.073*
C70.7296 (2)0.3877 (2)0.26657 (11)0.0521 (5)
H70.81840.40120.28510.063*
C80.6817 (2)0.44914 (18)0.20301 (11)0.0444 (5)
C90.5446 (2)0.42934 (17)0.17467 (10)0.0410 (5)
C100.8940 (2)0.5533 (2)0.18444 (13)0.0587 (6)
H10A0.94540.47550.18420.070*
H10B0.89960.58790.23560.070*
C110.9503 (2)0.6450 (2)0.12900 (15)0.0663 (7)
H11A0.93840.61130.07790.080*
H11B1.04720.65500.14010.080*
C120.8825 (2)0.7721 (2)0.13204 (13)0.0615 (6)
H12A0.78530.76180.12250.074*
H12B0.89690.80700.18270.074*
C130.9360 (2)0.8621 (2)0.07498 (13)0.0561 (6)
C140.6530 (2)0.90707 (19)−0.04826 (11)0.0451 (5)
H140.69490.9608−0.08180.054*
C150.5098 (2)0.87299 (17)−0.06186 (10)0.0422 (5)
C160.4388 (2)0.9199 (2)−0.12587 (12)0.0528 (5)
H160.48250.9730−0.15910.063*
C170.3046 (2)0.8885 (2)−0.14041 (13)0.0581 (6)
H170.25720.9203−0.18310.070*
C180.2416 (2)0.8095 (2)−0.09103 (12)0.0503 (5)
C190.3084 (2)0.7626 (2)−0.02718 (12)0.0518 (5)
H190.26350.71040.00600.062*
C200.4429 (2)0.79389 (19)−0.01275 (11)0.0475 (5)
H200.48920.76180.03020.057*

Atomic displacement parameters (Å2)

U11U22U33U12U13U23
O10.0511 (9)0.0703 (10)0.0573 (9)−0.0236 (8)−0.0086 (7)0.0125 (8)
O20.0459 (9)0.1000 (13)0.0779 (11)−0.0223 (9)−0.0080 (8)0.0215 (10)
O30.0686 (13)0.181 (2)0.1362 (19)0.0046 (16)−0.0528 (14)0.0321 (19)
O40.0516 (10)0.1168 (17)0.1021 (15)−0.0198 (11)−0.0025 (10)−0.0187 (13)
N10.0546 (11)0.0479 (10)0.0592 (11)−0.0031 (9)−0.0103 (9)0.0030 (8)
N20.0389 (9)0.0549 (10)0.0559 (10)−0.0102 (8)0.0021 (8)0.0007 (8)
N30.0387 (9)0.0472 (10)0.0541 (10)−0.0061 (8)0.0047 (8)−0.0070 (8)
N40.0460 (11)0.0887 (16)0.0770 (14)0.0091 (12)−0.0111 (11)−0.0183 (13)
C10.0564 (14)0.0588 (14)0.0781 (16)0.0060 (12)−0.0205 (12)−0.0039 (12)
C20.0432 (12)0.0687 (16)0.0928 (19)0.0000 (12)−0.0065 (13)−0.0211 (14)
C30.0516 (13)0.0623 (14)0.0801 (17)−0.0155 (12)0.0208 (12)−0.0221 (13)
C40.0523 (12)0.0399 (11)0.0505 (11)−0.0051 (10)0.0143 (9)−0.0121 (9)
C50.0829 (17)0.0493 (13)0.0499 (12)−0.0090 (12)0.0230 (12)−0.0003 (10)
C60.0850 (18)0.0582 (13)0.0385 (11)0.0083 (13)0.0041 (11)0.0062 (10)
C70.0559 (12)0.0575 (13)0.0425 (11)0.0029 (11)−0.0035 (9)−0.0026 (10)
C80.0461 (11)0.0435 (10)0.0435 (11)−0.0048 (9)0.0020 (9)−0.0023 (9)
C90.0455 (11)0.0357 (10)0.0416 (10)−0.0021 (9)0.0014 (8)−0.0041 (8)
C100.0422 (12)0.0608 (13)0.0725 (15)−0.0079 (11)−0.0037 (11)−0.0013 (11)
C110.0520 (13)0.0645 (15)0.0831 (16)−0.0131 (12)0.0126 (12)−0.0032 (13)
C120.0461 (12)0.0765 (16)0.0622 (14)−0.0066 (12)0.0054 (10)0.0092 (12)
C130.0434 (12)0.0658 (14)0.0590 (13)−0.0086 (11)0.0026 (10)0.0016 (11)
C140.0462 (11)0.0437 (11)0.0458 (11)−0.0065 (9)0.0059 (9)−0.0052 (9)
C150.0454 (11)0.0391 (10)0.0422 (10)0.0025 (9)0.0026 (9)−0.0075 (8)
C160.0618 (13)0.0492 (12)0.0473 (11)0.0026 (11)0.0006 (10)0.0035 (9)
C170.0603 (14)0.0613 (14)0.0514 (12)0.0178 (12)−0.0125 (11)−0.0031 (11)
C180.0391 (10)0.0548 (12)0.0563 (12)0.0081 (10)−0.0063 (9)−0.0134 (10)
C190.0436 (11)0.0564 (13)0.0555 (12)−0.0039 (10)0.0018 (9)−0.0008 (10)
C200.0430 (11)0.0543 (12)0.0448 (11)−0.0013 (10)−0.0047 (9)0.0012 (9)

Geometric parameters (Å, °)

O1—C81.363 (2)C7—C81.361 (3)
O1—C101.430 (2)C7—H70.9300
O2—C131.235 (2)C8—C91.433 (3)
O3—N41.208 (3)C10—C111.500 (3)
O4—N41.220 (3)C10—H10A0.9700
N1—C11.319 (3)C10—H10B0.9700
N1—C91.358 (2)C11—C121.508 (3)
N2—C131.343 (3)C11—H11A0.9700
N2—N31.377 (2)C11—H11B0.9700
N2—H2A0.8600C12—C131.497 (3)
N3—C141.269 (3)C12—H12A0.9700
N4—C181.471 (3)C12—H12B0.9700
C1—C21.394 (4)C14—C151.464 (3)
C1—H10.9300C14—H140.9300
C2—C31.354 (4)C15—C201.390 (3)
C2—H20.9300C15—C161.392 (3)
C3—C41.412 (3)C16—C171.375 (3)
C3—H30.9300C16—H160.9300
C4—C91.413 (3)C17—C181.374 (3)
C4—C51.421 (3)C17—H170.9300
C5—C61.348 (3)C18—C191.370 (3)
C5—H50.9300C19—C201.377 (3)
C6—C71.407 (3)C19—H190.9300
C6—H60.9300C20—H200.9300
C8—O1—C10118.32 (16)O1—C10—H10B110.2
C1—N1—C9117.24 (19)C11—C10—H10B110.2
C13—N2—N3121.83 (18)H10A—C10—H10B108.5
C13—N2—H2A119.1C10—C11—C12112.5 (2)
N3—N2—H2A119.1C10—C11—H11A109.1
C14—N3—N2115.79 (18)C12—C11—H11A109.1
O3—N4—O4123.0 (2)C10—C11—H11B109.1
O3—N4—C18118.4 (3)C12—C11—H11B109.1
O4—N4—C18118.6 (2)H11A—C11—H11B107.8
N1—C1—C2124.4 (2)C13—C12—C11112.35 (19)
N1—C1—H1117.8C13—C12—H12A109.1
C2—C1—H1117.8C11—C12—H12A109.1
C3—C2—C1118.6 (2)C13—C12—H12B109.1
C3—C2—H2120.7C11—C12—H12B109.1
C1—C2—H2120.7H12A—C12—H12B107.9
C2—C3—C4120.0 (2)O2—C13—N2119.3 (2)
C2—C3—H3120.0O2—C13—C12121.3 (2)
C4—C3—H3120.0N2—C13—C12119.38 (19)
C3—C4—C9116.9 (2)N3—C14—C15120.28 (19)
C3—C4—C5123.6 (2)N3—C14—H14119.9
C9—C4—C5119.41 (19)C15—C14—H14119.9
C6—C5—C4119.8 (2)C20—C15—C16118.90 (19)
C6—C5—H5120.1C20—C15—C14121.72 (18)
C4—C5—H5120.1C16—C15—C14119.38 (19)
C5—C6—C7121.9 (2)C17—C16—C15120.6 (2)
C5—C6—H6119.0C17—C16—H16119.7
C7—C6—H6119.0C15—C16—H16119.7
C8—C7—C6119.9 (2)C18—C17—C16119.1 (2)
C8—C7—H7120.0C18—C17—H17120.5
C6—C7—H7120.0C16—C17—H17120.5
C7—C8—O1125.06 (19)C19—C18—C17121.7 (2)
C7—C8—C9120.23 (19)C19—C18—N4118.3 (2)
O1—C8—C9114.71 (16)C17—C18—N4120.0 (2)
N1—C9—C4122.77 (18)C18—C19—C20119.2 (2)
N1—C9—C8118.49 (17)C18—C19—H19120.4
C4—C9—C8118.73 (17)C20—C19—H19120.4
O1—C10—C11107.34 (19)C19—C20—C15120.53 (19)
O1—C10—H10A110.2C19—C20—H20119.7
C11—C10—H10A110.2C15—C20—H20119.7
C13—N2—N3—C14−178.96 (19)C8—O1—C10—C11179.83 (18)
C9—N1—C1—C22.4 (3)O1—C10—C11—C1265.1 (3)
N1—C1—C2—C3−2.5 (4)C10—C11—C12—C13−178.24 (19)
C1—C2—C3—C40.2 (3)N3—N2—C13—O2180.00 (19)
C2—C3—C4—C91.7 (3)N3—N2—C13—C12−0.1 (3)
C2—C3—C4—C5−176.9 (2)C11—C12—C13—O2−66.0 (3)
C3—C4—C5—C6179.5 (2)C11—C12—C13—N2114.1 (2)
C9—C4—C5—C60.9 (3)N2—N3—C14—C15−179.17 (16)
C4—C5—C6—C70.4 (3)N3—C14—C15—C200.6 (3)
C5—C6—C7—C8−1.1 (3)N3—C14—C15—C16−178.84 (18)
C6—C7—C8—O1−178.65 (19)C20—C15—C16—C17−0.1 (3)
C6—C7—C8—C90.5 (3)C14—C15—C16—C17179.41 (18)
C10—O1—C8—C70.7 (3)C15—C16—C17—C18−0.3 (3)
C10—O1—C8—C9−178.53 (17)C16—C17—C18—C190.9 (3)
C1—N1—C9—C4−0.3 (3)C16—C17—C18—N4−178.20 (19)
C1—N1—C9—C8178.11 (19)O3—N4—C18—C19177.6 (2)
C3—C4—C9—N1−1.7 (3)O4—N4—C18—C19−4.7 (3)
C5—C4—C9—N1176.92 (18)O3—N4—C18—C17−3.2 (3)
C3—C4—C9—C8179.88 (18)O4—N4—C18—C17174.4 (2)
C5—C4—C9—C8−1.5 (3)C17—C18—C19—C20−1.1 (3)
C7—C8—C9—N1−177.70 (18)N4—C18—C19—C20178.07 (18)
O1—C8—C9—N11.6 (3)C18—C19—C20—C150.6 (3)
C7—C8—C9—C40.8 (3)C16—C15—C20—C19−0.1 (3)
O1—C8—C9—C4−179.99 (16)C14—C15—C20—C19−179.55 (18)

Hydrogen-bond geometry (Å, °)

D—H···AD—HH···AD···AD—H···A
N2—H2A···O2i0.862.032.876 (3)170
C12—H12A···O10.972.572.912 (3)101
C12—H12A···N30.972.332.807 (3)109
C10—H10B···O3ii0.972.453.311 (3)148
C2—H2···O4iii0.932.583.496 (3)167

Symmetry codes: (i) −x+2, −y+2, −z; (ii) x+1, −y+3/2, z+1/2; (iii) −x, −y+1, −z.

Footnotes

Supplementary data and figures for this paper are available from the IUCr electronic archives (Reference: ZS2040).

References

  • Allen, F. H., Kennard, O., Watson, D. G., Brammer, L., Orpen, A. G. & Taylor, R. J. (1987). J. Chem. Soc. Perkin Trans. 2, pp. S1–19.
  • Bernstein, J., Davis, R. E., Shimoni, L. & Chang, N.-L. (1995). Angew. Chem. Int. Ed. Engl.34, 1555–1573.
  • Bruker (2007). SMART and SAINT Bruker AXS Inc., Madison, Wisconsin, USA.
  • Calligaris, M. & Randaccio, L. (1987). Comprehensive Coordination Chemistry, Vol. 2, edited by G. Wilkinson, pp. 715–738. London: Pergamon.
  • Chen, M.-E. & Li, J.-M. (2009). Acta Cryst. E65, o295. [PMC free article] [PubMed]
  • Sheldrick, G. M. (1996). SADABS University of Göttingen, Germany.
  • Sheldrick, G. M. (2008). Acta Cryst. A64, 112–122. [PubMed]
  • Xie, H., Meng, S.-M., Fan, Y.-Q. & Yang, G.-C. (2008). Acta Cryst. E64, o2114. [PMC free article] [PubMed]
  • Zhang, J., XiaHou, G.-L., Zhang, S.-S. & Zeng, J. (2009). Acta Cryst. E65, o1695–o1696. [PMC free article] [PubMed]
  • Zheng, Z.-B. (2006). Acta Cryst. E62, o5146–o5147.
  • Zheng, Z.-B., Li, J.-K., Sun, Y.-F. & Wu, R.-T. (2008). Acta Cryst. E64, o297.
  • Zheng, P.-W., Qiu, Q.-M., Lin, Y.-Y. & Liu, K.-F. (2006). Acta Cryst. E62, o1913–o1914.
  • Zheng, Z.-B., Wu, R.-T., Li, J.-K. & Lu, J.-R. (2007). Acta Cryst. E63, o3284.
  • Zheng, Z.-B., Wu, R.-T., Li, J.-K. & Sun, Y.-F. (2006). Acta Cryst. E62, o4882–o4883.
  • Zheng, Z.-B., Wu, R.-T., Lu, J.-R. & Sun, Y.-F. (2006). Acta Cryst. E62, o4293–o4295.

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