PMCCPMCCPMCC

Search tips
Search criteria 

Advanced

 
Logo of actaeInternational Union of Crystallographysearchopen accessarticle submissionjournal home pagethis article
 
Acta Crystallogr Sect E Struct Rep Online. 2009 December 1; 65(Pt 12): m1704–m1705.
Published online 2009 November 28. doi:  10.1107/S1600536809050570
PMCID: PMC2971803

Poly[μ-aqua-diaqua­(μ2-pyrazine-2,3-dicarboxyl­ato)dilithium(I)]

Abstract

The asymmetric unit of the title compound, [Li2(C6H2N2O4)(H2O)3]n, consists of two independent Li+ cations, one pyrazine-2,3-dicarboxyl­ate dianion and three water mol­ecules. One of the Li+ cations has a distorted tetra­hedral geometry, coordinated by one of the carboxyl­ate O atoms of the pyrazine-2,3-dicarboxyl­ate ligand and three O atoms from three water mol­ecules, whereas the other Li+ cation has a distorted trigonal-bipyramidal geometry, coordinated by a carboxyl­ate O atom of a symmetry-related pyrazine-2,3-dicarboxyl­ate ligand, two water mol­ecules and a chelating pyrazine-2,3-dicarboxyl­ate ligand (by utilizing both N and O atoms) of an adjacent mol­ecule. The synthesis of a hydrated polymeric dinuclear lithium complex formed with two pyrazine-2,3-dicarboxylic acid ligands has been reported previously [Tombul et al. (2008a [triangle]). Acta Cryst. E64, m491–m492]. By comparision to the complex reported here, the dinuclear complex formed with two pyrazine-2,3-dicarboxylic acid ligands differs in the coordination geometry of both Li atoms. The crystal structure further features O—H(...)O and O—H(...)N hydrogen-bonding inter­actions involving the water mol­ecules and carboxyl­ate O atoms.

Related literature

For a general background to multidendate carboxylic acids, see: Erxleben (2003 [triangle]); Ye et al. (2005 [triangle]); Fei et al. (2006 [triangle]). For further information on pyrazine-2,3-dicarboxylic acid, see: Takusagawa & Shimada (1973 [triangle]); Richard et al. (1973 [triangle]); Nepveu et al. (1993 [triangle]). For further information on the synthesis of metal complexes with pyrazine-2,3-dicarboxylic acid ligand, see: Tombul & Güven (2009 [triangle]); Tombul et al. (2006 [triangle], 2007 [triangle], 2008b [triangle]). For a related structure of lithium with pyrazine-2,3-dicarb­oxylic acid ligand, see: Tombul et al. (2008a [triangle]). For Li—O bond distances, see: Chen et al. (2007 [triangle]); Kim et al. (2007 [triangle]). For Li—N bond lengths, see: Grossie et al. (2006 [triangle]); Boyd et al. (2002 [triangle]).

An external file that holds a picture, illustration, etc.
Object name is e-65-m1704-scheme1.jpg

Experimental

Crystal data

  • [Li2(C6H2N2O4)(H2O)3]
  • M r = 234.02
  • Monoclinic, An external file that holds a picture, illustration, etc.
Object name is e-65-m1704-efi3.jpg
  • a = 7.487 (3) Å
  • b = 16.409 (8) Å
  • c = 7.958 (2) Å
  • β = 92.92 (3)°
  • V = 976.4 (7) Å3
  • Z = 4
  • Mo Kα radiation
  • μ = 0.14 mm−1
  • T = 298 K
  • 0.40 × 0.20 × 0.06 mm

Data collection

  • Rigaku AFC-7S diffractometer
  • Absorption correction: ψ scan (North et al., 1968 [triangle]) T min = 0.948, T max = 0.994
  • 6366 measured reflections
  • 6045 independent reflections
  • 2427 reflections with I > 2σ(I)
  • R int = 0.120
  • 3 standard reflections frequency: 150 reflections intensity decay: none

Refinement

  • R[F 2 > 2σ(F 2)] = 0.062
  • wR(F 2) = 0.211
  • S = 0.96
  • 6045 reflections
  • 178 parameters
  • H atoms treated by a mixture of independent and constrained refinement
  • Δρmax = 0.49 e Å−3
  • Δρmin = −0.54 e Å−3

Data collection: MSC/AFC Diffractometer Control Software (Molecular Structure Corporation, 1989 [triangle]); cell refinement: MSC/AFC Diffractometer Control Software; data reduction: TEXSAN (Molec­ular Structure Corporation, 1993 [triangle]); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 [triangle]); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 [triangle]); molecular graphics: Mercury (Macrae et al., 2008 [triangle]); software used to prepare material for publication: publCIF (Westrip, 2009 [triangle]).

Table 1
Selected bond lengths (Å)
Table 2
Hydrogen-bond geometry (Å, °)

Supplementary Material

Crystal structure: contains datablocks global, I. DOI: 10.1107/S1600536809050570/om2293sup1.cif

Structure factors: contains datablocks I. DOI: 10.1107/S1600536809050570/om2293Isup2.hkl

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

Acknowledgments

The authors are grateful to Kirikkale University Scientific Research Centre, (BAP-Kirikkale), Turkey, for their generous support.

supplementary crystallographic information

Comment

Multidendate carboxylic acids are found to be excellent ligands for the synthesis of coordination polymers, giving structures with a diverse range of topologies and conformations, owing to the carboxylate groups being able to coordinate to a metal centre as a mono-, bi-, or multidentate ligand (Erxleben, 2003; Ye et al., 2005; Fei et al., 2006). Pyrazine-2,3-dicarboxylic acid (Takusagawa & Shimada, 1973) and its dianion (Richard et al., 1973; Nepveu et al., 1993) have been reported to be well suited for the construction of multidimentional frameworks (nD, n = 1–3), due to the presence of two adjacent carboxylate groups (O donor atoms) as substituents on the N-heterocyclic pyrazine ring (N donor atoms). In recent years, metal complexes with pyrazine-2,3-dicarboxylic acid ligand have been extensively studied because of their wide applications and growing interest in supramolecular chemistry. Examples include sodium (Tombul et al., 2006), caesium (Tombul et al., 2007), potassium (Tombul et al., 2008b), lithium (Tombul et al., 2008a) and rubidium (Tombul & Guven, 2009) complexes. As a continuation of our ongoing research on Group I dicarboxylates, we report here the synthesis and crystal structure of the hydrated polymeric dinuclear lithium complex formed with one molar equivalent of pyrazine-2,3-dicarboxylic acid.

As shown in Fig. 1, the title compound is a polymeric dinuclear complex with two kinds of Li atoms, one pyrazine-2,3-dicarboxylate ligand and three water molecules in the asymmetric unit. The geometries of the two independent Li atoms are different and the coordination modes of the pyrazine-2,3-dicarboxylate towards the cations are dissimilar. The Li1 ion has a distorted four-coordinate geometry and achieves the coordination number by bonding to one of the carboxylate O atom of pyrazine-2,3-dicarboxylate ligand, three O atoms from three water molecules, one of which is a symmetry-related bridging O atom. The Li2 ion has a distorted trigonal bipyramidal geometry, with one water molecule in bridging mode that connects the two distinct Li ions, one symmetry related carboxylate O atom of pyrazine-2,3-dicarboxylate ligand and a chelated pyrazine-2,3-dicarboxylate ligand (through the interactions of both N and O atoms) of the adjacent molecule. It should be emphasized that, depending on the starting material and stoichiometric ratio utilized, the synthesis of dinuclear lithium complexes formed with one or two pyrazine-2,3-dicarboxylic acid ligands can be accessible (Tombul et al., 2008a). The Li–O distances are in the range 1.918 (4)Å to 2.046 (4)Å (for Li1) and 1.942 (3)Å to 2.129 (4)Å (for Li2), in good agreement with the corresponding values reported for other lithium complexes (Chen et al., 2007; Kim et al., 2007). It is interesting to note that Li–N bond lengths are in accord with the normal ranges reported for the dinuclear bis-structure (Tombul et al., 2008a), however, the Li–N distances are notably longer than similar bond lengths reported in the literature (Grossie et al., 2006; Boyd et al., 2002). The dinuclear complex is linked in a three-dimensional manner by further intra- and intermolecular O—H–O and O—H–N hydrogen bonds (Figure 2 and Table 2).

Experimental

To an aqueous solution (30 ml) of pyrazine 2,3-dicarboxylic acid (1681 mg, 1 mmol), LiOH (479 mg, 2 mmol) was carefully added. The reaction mixture gave a colourless and clear solution which was stirred at 303 K for 4 h. After solvent removal in vacuo, the white solid product was then redissolved in water (5 ml) and allowed to stand for 15 d at ambient temperature, after which transparent fine crystals were harvested from the mother liquor.

Refinement

H atoms associated with water molecules were located in the difference map and freely refined during subsequent cycles of least squares. H atoms of carbons were repositioned geometrically. They were initially refined with soft restraints on the bond lengths and angles to regularize their geometry (C—H = 0.93 Å) and Uĩso~(H) (in the range 1.2–1.5 times U~eq~ of the parent atom) ,after which the positions were refined with riding constraints.

Figures

Fig. 1.
Showing the atom-labelling scheme with symmetry codes: ii = -x, y + 1/2, -z + 1/2; iii = -x, -y + 1, -z + 1.)] Atoms were drawn with 50% thermal ellipsoid probability contours.
Fig. 2.
A view of the hydrogen bonding interactions in the structure. Symmetry codes: iv = -x + 1, -y + 1, -z + 1; v = -x, -y + 1, -z; vi = x - 1, y, z]. Atoms were drawn with 50% thermal ellipsoid probability contours.

Crystal data

[Li2(C6H2N2O4)(H2O)3]F(000) = 480
Mr = 234.02Dx = 1.592 Mg m3
Monoclinic, P21/cMo Kα radiation, λ = 0.71069 Å
Hall symbol: -P 2ybcCell parameters from 25 reflections
a = 7.487 (3) Åθ = 3.0–7.9°
b = 16.409 (8) ŵ = 0.14 mm1
c = 7.958 (2) ÅT = 298 K
β = 92.92 (3)°Prism, yellow
V = 976.4 (7) Å30.4 × 0.2 × 0.06 mm
Z = 4

Data collection

Rigaku diffractometer2427 reflections with I > 2σ(I)
Radiation source: fine-focus sealed tubeRint = 0.120
graphiteθmax = 40.0°, θmin = 2.7°
ω–2θ scansh = 0→13
Absorption correction: ψ scan (North et al., 1968)k = 0→29
Tmin = 0.948, Tmax = 0.994l = −14→14
6366 measured reflections3 standard reflections every 150 reflections
6045 independent reflections intensity decay: none

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)] = 0.062Hydrogen site location: inferred from neighbouring sites
wR(F2) = 0.211H atoms treated by a mixture of independent and constrained refinement
S = 0.96w = 1/[σ2(Fo2) + (0.0977P)2] where P = (Fo2 + 2Fc2)/3
6045 reflections(Δ/σ)max < 0.001
178 parametersΔρmax = 0.49 e Å3
0 restraintsΔρmin = −0.54 e Å3

Special details

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.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2)

xyzUiso*/Ueq
O1−0.01123 (18)0.24672 (8)0.0505 (2)0.0341 (3)
O20.06063 (17)0.37715 (7)0.09640 (16)0.0236 (3)
O30.20616 (17)0.43281 (7)0.43623 (16)0.0238 (3)
O40.39167 (18)0.47554 (7)0.24601 (18)0.0277 (3)
O50.03262 (19)0.56609 (8)0.21735 (17)0.0252 (3)
H5A0.004 (4)0.5875 (17)0.129 (4)0.043 (8)*
H5B0.147 (5)0.558 (2)0.222 (4)0.069 (10)*
O60.17467 (17)0.58515 (8)0.56590 (16)0.0224 (2)
H6A0.272 (4)0.613 (2)0.581 (4)0.058 (9)*
H6B0.206 (4)0.5391 (19)0.519 (3)0.048 (8)*
O7−0.2951 (2)0.46974 (13)0.0850 (2)0.0479 (5)
H7A−0.316 (5)0.501 (2)−0.004 (5)0.082 (12)*
H7B−0.394 (5)0.465 (2)0.139 (4)0.064 (10)*
N10.29092 (19)0.19673 (8)0.21499 (19)0.0228 (3)
N20.52735 (19)0.30911 (9)0.3651 (2)0.0246 (3)
C10.0838 (2)0.30153 (9)0.1146 (2)0.0195 (3)
C20.2524 (2)0.27631 (9)0.2158 (2)0.0172 (3)
C30.4472 (3)0.17365 (11)0.2881 (3)0.0296 (4)
H30.47610.11850.29200.036*
C40.5669 (2)0.22967 (11)0.3582 (3)0.0300 (4)
H40.67770.21180.40170.036*
C50.3672 (2)0.33240 (9)0.2984 (2)0.0171 (3)
C60.31766 (19)0.42055 (9)0.3264 (2)0.0168 (3)
Li1−0.0795 (5)0.4524 (2)0.2209 (4)0.0289 (7)
Li2−0.0490 (4)0.63229 (18)0.4210 (4)0.0252 (6)

Atomic displacement parameters (Å2)

U11U22U33U12U13U23
O10.0312 (7)0.0205 (6)0.0488 (9)−0.0017 (5)−0.0159 (6)−0.0045 (6)
O20.0304 (6)0.0161 (5)0.0240 (6)0.0064 (4)−0.0028 (5)−0.0005 (4)
O30.0310 (6)0.0158 (5)0.0257 (6)0.0022 (4)0.0123 (5)0.0002 (4)
O40.0300 (6)0.0176 (5)0.0367 (7)−0.0035 (4)0.0129 (5)0.0050 (5)
O50.0298 (6)0.0255 (6)0.0201 (6)0.0068 (5)0.0016 (5)0.0034 (5)
O60.0224 (5)0.0192 (5)0.0253 (6)−0.0002 (4)−0.0005 (4)−0.0020 (4)
O70.0300 (8)0.0775 (14)0.0371 (9)0.0162 (8)0.0109 (6)0.0208 (9)
N10.0256 (7)0.0129 (5)0.0297 (7)0.0026 (5)−0.0004 (5)−0.0022 (5)
N20.0191 (6)0.0208 (6)0.0334 (8)0.0025 (5)−0.0024 (5)−0.0025 (5)
C10.0225 (7)0.0161 (6)0.0197 (7)0.0025 (5)−0.0008 (5)−0.0017 (5)
C20.0178 (6)0.0133 (5)0.0209 (7)0.0012 (5)0.0024 (5)−0.0005 (5)
C30.0296 (8)0.0169 (7)0.0417 (11)0.0074 (6)−0.0043 (7)−0.0015 (7)
C40.0229 (7)0.0224 (7)0.0438 (11)0.0083 (6)−0.0060 (7)−0.0020 (7)
C50.0180 (6)0.0132 (5)0.0201 (7)0.0007 (5)0.0022 (5)0.0000 (5)
C60.0174 (6)0.0120 (5)0.0212 (7)−0.0002 (4)0.0016 (5)0.0002 (5)
Li10.0367 (17)0.0197 (13)0.0312 (17)0.0031 (12)0.0100 (13)0.0010 (12)
Li20.0300 (15)0.0163 (12)0.0294 (16)0.0004 (11)0.0045 (12)0.0027 (11)

Geometric parameters (Å, °)

O5—Li12.046 (4)N2—C41.338 (2)
O5—Li22.069 (4)N2—C51.342 (2)
O5—H5B0.87 (4)C2—C51.400 (2)
O5—H5A0.80 (3)C2—C11.519 (2)
O4—C61.2517 (19)C5—C61.513 (2)
O6—Li22.129 (4)C4—C31.382 (3)
O6—H6A0.87 (3)C4—H40.9300
O6—H6B0.88 (3)C3—H30.9300
O1—C11.241 (2)Li2—O1ii1.942 (3)
O2—C11.260 (2)Li2—O3iii1.988 (3)
O2—Li11.927 (3)Li2—N1ii2.317 (4)
O3—C61.2552 (19)Li1—O71.918 (4)
N1—C31.335 (2)Li1—O6iii1.973 (4)
N1—C21.337 (2)O7—H7A0.88 (4)
N1—Li2i2.317 (4)O7—H7B0.88 (4)
Li1—O5—Li2109.27 (14)N1—C3—C4121.58 (16)
Li1—O5—H5B105 (2)N1—C3—H3119.2
Li2—O5—H5B112 (2)C4—C3—H3119.2
Li1—O5—H5A109 (2)O1—C1—O2126.41 (15)
Li2—O5—H5A112 (2)O1—C1—C2117.66 (14)
H5B—O5—H5A109 (3)O2—C1—C2115.79 (14)
Li1iii—O6—Li2105.71 (15)O4—C6—O3124.60 (14)
Li1iii—O6—H6A112 (2)O4—C6—C5119.72 (14)
Li2—O6—H6A121 (2)O3—C6—C5115.64 (13)
Li1iii—O6—H6B102.5 (18)O1ii—Li2—O3iii126.42 (18)
Li2—O6—H6B107.5 (18)O1ii—Li2—O5121.53 (17)
H6A—O6—H6B106 (3)O3iii—Li2—O5111.87 (15)
C1—O1—Li2i121.88 (15)O1ii—Li2—O696.70 (15)
C1—O2—Li1130.35 (15)O3iii—Li2—O688.14 (13)
C6—O3—Li2iii138.22 (14)O5—Li2—O688.74 (13)
C3—N1—C2117.34 (14)O1ii—Li2—N1ii77.56 (12)
C3—N1—Li2i136.14 (14)O3iii—Li2—N1ii92.34 (14)
C2—N1—Li2i106.51 (13)O5—Li2—N1ii97.38 (14)
C4—N2—C5117.17 (15)O6—Li2—N1ii173.18 (17)
N1—C2—C5121.12 (14)O7—Li1—O2105.65 (18)
N1—C2—C1115.90 (13)O7—Li1—O6iii101.58 (17)
C5—C2—C1122.89 (13)O2—Li1—O6iii118.14 (18)
N2—C5—C2120.88 (14)O7—Li1—O5101.05 (17)
N2—C5—C6115.78 (13)O2—Li1—O5110.05 (17)
C2—C5—C6123.27 (13)O6iii—Li1—O5117.60 (17)
N2—C4—C3121.58 (16)Li1—O7—H7A130 (3)
N2—C4—H4119.2Li1—O7—H7B115 (2)
C3—C4—H4119.2H7A—O7—H7B109 (3)
C3—N1—C2—C5−3.5 (2)C5—C2—C1—O26.1 (2)
Li2i—N1—C2—C5176.03 (15)Li2iii—O3—C6—O4174.97 (19)
C3—N1—C2—C1173.33 (16)Li2iii—O3—C6—C5−7.5 (3)
Li2i—N1—C2—C1−7.18 (18)N2—C5—C6—O473.8 (2)
C4—N2—C5—C2−4.0 (3)C2—C5—C6—O4−109.25 (19)
C4—N2—C5—C6172.98 (16)N2—C5—C6—O3−103.86 (18)
N1—C2—C5—N26.5 (3)C2—C5—C6—O373.1 (2)
C1—C2—C5—N2−170.03 (15)Li1—O5—Li2—O1ii−174.09 (18)
N1—C2—C5—C6−170.25 (15)Li1—O5—Li2—O3iii1.3 (2)
C1—C2—C5—C613.2 (2)Li1—O5—Li2—O688.83 (16)
C5—N2—C4—C3−1.1 (3)Li1—O5—Li2—N1ii−94.19 (16)
C2—N1—C3—C4−1.6 (3)Li1iii—O6—Li2—O1ii105.93 (16)
Li2i—N1—C3—C4179.05 (19)Li1iii—O6—Li2—O3iii−20.53 (16)
N2—C4—C3—N14.1 (3)Li1iii—O6—Li2—O5−132.46 (14)
Li2i—O1—C1—O2176.24 (17)C1—O2—Li1—O7−101.2 (2)
Li2i—O1—C1—C20.7 (2)C1—O2—Li1—O6iii11.5 (3)
Li1—O2—C1—O187.8 (3)C1—O2—Li1—O5150.45 (16)
Li1—O2—C1—C2−96.7 (2)Li2—O5—Li1—O791.67 (18)
N1—C2—C1—O15.3 (2)Li2—O5—Li1—O2−156.99 (16)
C5—C2—C1—O1−177.97 (16)Li2—O5—Li1—O6iii−17.8 (2)
N1—C2—C1—O2−170.67 (15)

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

Hydrogen-bond geometry (Å, °)

D—H···AD—HH···AD···AD—H···A
O5—H5A···O2iv0.81 (3)1.92 (3)2.723 (3)172.60 (3)
O5—H5B···O40.87 (4)2.28 (4)3.068 (3)152 (3)
O6—H6A···N2v0.86 (3)2.00 (3)2.857 (3)169.66 (4)
O6—H6B···O30.88 (3)1.86 (3)2.719 (3)163 (3)
O7—H7A···O4iv0.88 (4)2.02 (4)2.841 (3)154.89 (6)
O7—H7B···O4vi0.88 (4)1.86 (4)2.730 (3)169.51 (6)

Symmetry codes: (iv) −x, −y+1, −z; (v) −x+1, −y+1, −z+1; (vi) x−1, y, z.

Footnotes

Supplementary data and figures for this paper are available from the IUCr electronic archives (Reference: OM2293).

References

  • Boyd, C. L., Tyrrell, B. R. & Mountford, P. (2002). Acta Cryst. E58, m597–m598.
  • Chen, Z., Fei, Z., Zhao, D., Feng, Y. & Yu, K. (2007). Inorg. Chem. Commun. 10, 77–79.
  • Erxleben, A. (2003). Coord. Chem. Rev. 246, 203–228.
  • Fei, Z., Geldbach, T. J., Zhao, D. & Dyson, P. J. (2006). Chem. Eur. J. 12, 2122–2130. [PubMed]
  • Grossie, D. A., Feld, W. A., Scanlon, L., Sandi, G. & Wawrzak, Z. (2006). Acta Cryst. E62, m827–m829.
  • Kim, E.-J., Kim, C.-H. & Yun, S.-S. (2007). Acta Cryst. C63, m427–m429. [PubMed]
  • Macrae, C. F., Bruno, I. J., Chisholm, J. A., Edgington, P. R., McCabe, P., Pidcock, E., Rodriguez-Monge, L., Taylor, R., van de Streek, J. & Wood, P. A. (2008). J. Appl. Cryst. 41, 466–470.
  • Molecular Structure Corporation (1989). MSC/AFC Diffractometer Control Software. MSC, The Woodlands, Texas, USA.
  • Molecular Structure Corporation (1993). TEXSAN TEXRAY Structure Analysis Package. MSC, The Woodlands, Texas, USA.
  • Nepveu, F., Berkaoui, M. ’H. & Walz, L. (1993). Acta Cryst. C49, 1465–1466.
  • North, A. C. T., Phillips, D. C. & Mathews, F. S. (1968). Acta Cryst. A24, 351–359.
  • Richard, P., Tran Qui, D. & Bertaut, E. F. (1973). Acta Cryst. B29, 1111–1115.
  • Sheldrick, G. M. (2008). Acta Cryst. A64, 112–122. [PubMed]
  • Takusagawa, T. & Shimada, A. (1973). Chem. Lett. pp. 1121–1126.
  • Tombul, M. & Güven, K. (2009). Acta Cryst. E65, m213–m214. [PMC free article] [PubMed]
  • Tombul, M., Güven, K. & Alkış, N. (2006). Acta Cryst. E62, m945–m947.
  • Tombul, M., Güven, K. & Büyükgüngör, O. (2007). Acta Cryst. E63, m1783–m1784.
  • Tombul, M., Güven, K. & Büyükgüngör, O. (2008a). Acta Cryst. E64, m491–m492. [PMC free article] [PubMed]
  • Tombul, M., Güven, K. & Svoboda, I. (2008b). Acta Cryst. E64, m246–m247. [PMC free article] [PubMed]
  • Westrip, S. P. (2009). publCIF. In preparation.
  • Ye, B.-H., Tong, M.-L. & Chen, X.-M. (2005). Coord. Chem. Rev. 249, 545–565.

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