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

Tombul, M.; Guven, K.

doi:10.1107/S1600536809050570

metal-organic compounds

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ISSN: 2056-9890

Volume 65| Part 12| December 2009| Pages m1704-m1705

doi:10.1107/S1600536809050570

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

Mustafa Tombul ^a ^* and Kutalmis Guven ^b

^aDepartment of Chemistry, Faculty of Art and Science, University of Kirikkale, Campus, Yahsihan, Kirikkale, 71450 Kirikkale, Turkey, and ^bDepartment of Physics, Faculty of Art and Science, University of Kirikkale, Campus, Yahsihan, Kirikkale, 71450 Kirikkale, Turkey
^*Correspondence e-mail: mustafatombul38@gmail.com

(Received 20 October 2009; accepted 24 November 2009; online 28 November 2009)

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

Experimental

Crystal data

[Li₂(C₆H₂N₂O₄)(H₂O)₃]
M_r = 234.02
Monoclinic, P 2₁ /c
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 ) 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[F² > 2σ(F²)] = 0.062
wR(F²) = 0.211
S = 0.96
6045 reflections
178 parameters
H atoms treated by a mixture of independent and constrained refinement
Δρ_max = 0.49 e Å⁻³
Δρ_min = −0.54 e Å⁻³

Table 1
Selected bond lengths (Å)

O5—Li1	2.046 (4)
O5—Li2	2.069 (4)
O6—Li2	2.129 (4)
O2—Li1	1.927 (3)
N1—Li2ⁱ	2.317 (4)
Li2—O1ⁱⁱ	1.942 (3)
Li2—O3ⁱⁱⁱ	1.988 (3)
Li1—O7	1.918 (4)
Li1—O6ⁱⁱⁱ	1.973 (4)
Symmetry codes: (i) $[-x, y-{\script{1\over 2}}, -z+{\script{1\over 2}}]$ ; (ii) $[-x, y+{\script{1\over 2}}, -z+{\script{1\over 2}}]$ ; (iii) -x, -y+1, -z+1.

Table 2
Hydrogen-bond geometry (Å, °)

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
O5—H5A⋯O2^iv	0.81 (3)	1.92 (3)	2.723 (3)	172.60 (3)
O5—H5B⋯O4	0.87 (4)	2.28 (4)	3.068 (3)	152 (3)
O6—H6A⋯N2^v	0.86 (3)	2.00 (3)	2.857 (3)	169.66 (4)
O6—H6B⋯O3	0.88 (3)	1.86 (3)	2.719 (3)	163 (3)
O7—H7A⋯O4^iv	0.88 (4)	2.02 (4)	2.841 (3)	154.89 (6)
O7—H7B⋯O4^vi	0.88 (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.

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

Supporting information

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

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

checkCIF report

Comment top

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).

Related literature top

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

Experimental top

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.

Computing details top

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

Figures top

	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.

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

Crystal data top

[Li₂(C₆H₂N₂O₄)(H₂O)₃]	F(000) = 480
M_r = 234.02	D_x = 1.592 Mg m⁻³
Monoclinic, P2₁/c	Mo Kα radiation, λ = 0.71069 Å
Hall symbol: -P 2ybc	Cell parameters from 25 reflections
a = 7.487 (3) Å	θ = 3.0–7.9°
b = 16.409 (8) Å	µ = 0.14 mm⁻¹
c = 7.958 (2) Å	T = 298 K
β = 92.92 (3)°	Prism, yellow
V = 976.4 (7) Å³	0.4 × 0.2 × 0.06 mm
Z = 4

Data collection top

Rigaku diffractometer	2427 reflections with I > 2σ(I)
Radiation source: fine-focus sealed tube	R_int = 0.120
Graphite monochromator	θ_max = 40.0°, θ_min = 2.7°
ω–2θ scans	h = 0→13
Absorption correction: ψ scan (North et al., 1968)	k = 0→29
T_min = 0.948, T_max = 0.994	l = −14→14
6366 measured reflections	3 standard reflections every 150 reflections
6045 independent reflections	intensity decay: none

Refinement top

Refinement on F²	Primary atom site location: structure-invariant direct methods
Least-squares matrix: full	Secondary atom site location: difference Fourier map
R[F² > 2σ(F²)] = 0.062	Hydrogen site location: inferred from neighbouring sites
wR(F²) = 0.211	H atoms treated by a mixture of independent and constrained refinement
S = 0.96	w = 1/[σ²(F_o²) + (0.0977P)²] where P = (F_o² + 2F_c²)/3
6045 reflections	(Δ/σ)_max < 0.001
178 parameters	Δρ_max = 0.49 e Å⁻³
0 restraints	Δρ_min = −0.54 e Å⁻³

Crystal data top

[Li₂(C₆H₂N₂O₄)(H₂O)₃]	V = 976.4 (7) Å³
M_r = 234.02	Z = 4
Monoclinic, P2₁/c	Mo Kα radiation
a = 7.487 (3) Å	µ = 0.14 mm⁻¹
b = 16.409 (8) Å	T = 298 K
c = 7.958 (2) Å	0.4 × 0.2 × 0.06 mm
β = 92.92 (3)°

Data collection top

Rigaku diffractometer	2427 reflections with I > 2σ(I)
Absorption correction: ψ scan (North et al., 1968)	R_int = 0.120
T_min = 0.948, T_max = 0.994	3 standard reflections every 150 reflections
6366 measured reflections	intensity decay: none
6045 independent reflections

Refinement top

R[F² > 2σ(F²)] = 0.062	0 restraints
wR(F²) = 0.211	H atoms treated by a mixture of independent and constrained refinement
S = 0.96	Δρ_max = 0.49 e Å⁻³
6045 reflections	Δρ_min = −0.54 e Å⁻³
178 parameters

Special details top

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) top

	x	y	z	U_iso*/U_eq
O1	−0.01123 (18)	0.24672 (8)	0.0505 (2)	0.0341 (3)
O2	0.06063 (17)	0.37715 (7)	0.09640 (16)	0.0236 (3)
O3	0.20616 (17)	0.43281 (7)	0.43623 (16)	0.0238 (3)
O4	0.39167 (18)	0.47554 (7)	0.24601 (18)	0.0277 (3)
O5	0.03262 (19)	0.56609 (8)	0.21735 (17)	0.0252 (3)
H5A	0.004 (4)	0.5875 (17)	0.129 (4)	0.043 (8)*
H5B	0.147 (5)	0.558 (2)	0.222 (4)	0.069 (10)*
O6	0.17467 (17)	0.58515 (8)	0.56590 (16)	0.0224 (2)
H6A	0.272 (4)	0.613 (2)	0.581 (4)	0.058 (9)*
H6B	0.206 (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)*
N1	0.29092 (19)	0.19673 (8)	0.21499 (19)	0.0228 (3)
N2	0.52735 (19)	0.30911 (9)	0.3651 (2)	0.0246 (3)
C1	0.0838 (2)	0.30153 (9)	0.1146 (2)	0.0195 (3)
C2	0.2524 (2)	0.27631 (9)	0.2158 (2)	0.0172 (3)
C3	0.4472 (3)	0.17365 (11)	0.2881 (3)	0.0296 (4)
H3	0.4761	0.1185	0.2920	0.036*
C4	0.5669 (2)	0.22967 (11)	0.3582 (3)	0.0300 (4)
H4	0.6777	0.2118	0.4017	0.036*
C5	0.3672 (2)	0.33240 (9)	0.2984 (2)	0.0171 (3)
C6	0.31766 (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) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
O1	0.0312 (7)	0.0205 (6)	0.0488 (9)	−0.0017 (5)	−0.0159 (6)	−0.0045 (6)
O2	0.0304 (6)	0.0161 (5)	0.0240 (6)	0.0064 (4)	−0.0028 (5)	−0.0005 (4)
O3	0.0310 (6)	0.0158 (5)	0.0257 (6)	0.0022 (4)	0.0123 (5)	0.0002 (4)
O4	0.0300 (6)	0.0176 (5)	0.0367 (7)	−0.0035 (4)	0.0129 (5)	0.0050 (5)
O5	0.0298 (6)	0.0255 (6)	0.0201 (6)	0.0068 (5)	0.0016 (5)	0.0034 (5)
O6	0.0224 (5)	0.0192 (5)	0.0253 (6)	−0.0002 (4)	−0.0005 (4)	−0.0020 (4)
O7	0.0300 (8)	0.0775 (14)	0.0371 (9)	0.0162 (8)	0.0109 (6)	0.0208 (9)
N1	0.0256 (7)	0.0129 (5)	0.0297 (7)	0.0026 (5)	−0.0004 (5)	−0.0022 (5)
N2	0.0191 (6)	0.0208 (6)	0.0334 (8)	0.0025 (5)	−0.0024 (5)	−0.0025 (5)
C1	0.0225 (7)	0.0161 (6)	0.0197 (7)	0.0025 (5)	−0.0008 (5)	−0.0017 (5)
C2	0.0178 (6)	0.0133 (5)	0.0209 (7)	0.0012 (5)	0.0024 (5)	−0.0005 (5)
C3	0.0296 (8)	0.0169 (7)	0.0417 (11)	0.0074 (6)	−0.0043 (7)	−0.0015 (7)
C4	0.0229 (7)	0.0224 (7)	0.0438 (11)	0.0083 (6)	−0.0060 (7)	−0.0020 (7)
C5	0.0180 (6)	0.0132 (5)	0.0201 (7)	0.0007 (5)	0.0022 (5)	0.0000 (5)
C6	0.0174 (6)	0.0120 (5)	0.0212 (7)	−0.0002 (4)	0.0016 (5)	0.0002 (5)
Li1	0.0367 (17)	0.0197 (13)	0.0312 (17)	0.0031 (12)	0.0100 (13)	0.0010 (12)
Li2	0.0300 (15)	0.0163 (12)	0.0294 (16)	0.0004 (11)	0.0045 (12)	0.0027 (11)

Geometric parameters (Å, º) top

O5—Li1	2.046 (4)	N2—C4	1.338 (2)
O5—Li2	2.069 (4)	N2—C5	1.342 (2)
O5—H5B	0.87 (4)	C2—C5	1.400 (2)
O5—H5A	0.80 (3)	C2—C1	1.519 (2)
O4—C6	1.2517 (19)	C5—C6	1.513 (2)
O6—Li2	2.129 (4)	C4—C3	1.382 (3)
O6—H6A	0.87 (3)	C4—H4	0.9300
O6—H6B	0.88 (3)	C3—H3	0.9300
O1—C1	1.241 (2)	Li2—O1ⁱⁱ	1.942 (3)
O2—C1	1.260 (2)	Li2—O3ⁱⁱⁱ	1.988 (3)
O2—Li1	1.927 (3)	Li2—N1ⁱⁱ	2.317 (4)
O3—C6	1.2552 (19)	Li1—O7	1.918 (4)
N1—C3	1.335 (2)	Li1—O6ⁱⁱⁱ	1.973 (4)
N1—C2	1.337 (2)	O7—H7A	0.88 (4)
N1—Li2ⁱ	2.317 (4)	O7—H7B	0.88 (4)

Li1—O5—Li2	109.27 (14)	N1—C3—C4	121.58 (16)
Li1—O5—H5B	105 (2)	N1—C3—H3	119.2
Li2—O5—H5B	112 (2)	C4—C3—H3	119.2
Li1—O5—H5A	109 (2)	O1—C1—O2	126.41 (15)
Li2—O5—H5A	112 (2)	O1—C1—C2	117.66 (14)
H5B—O5—H5A	109 (3)	O2—C1—C2	115.79 (14)
Li1ⁱⁱⁱ—O6—Li2	105.71 (15)	O4—C6—O3	124.60 (14)
Li1ⁱⁱⁱ—O6—H6A	112 (2)	O4—C6—C5	119.72 (14)
Li2—O6—H6A	121 (2)	O3—C6—C5	115.64 (13)
Li1ⁱⁱⁱ—O6—H6B	102.5 (18)	O1ⁱⁱ—Li2—O3ⁱⁱⁱ	126.42 (18)
Li2—O6—H6B	107.5 (18)	O1ⁱⁱ—Li2—O5	121.53 (17)
H6A—O6—H6B	106 (3)	O3ⁱⁱⁱ—Li2—O5	111.87 (15)
C1—O1—Li2ⁱ	121.88 (15)	O1ⁱⁱ—Li2—O6	96.70 (15)
C1—O2—Li1	130.35 (15)	O3ⁱⁱⁱ—Li2—O6	88.14 (13)
C6—O3—Li2ⁱⁱⁱ	138.22 (14)	O5—Li2—O6	88.74 (13)
C3—N1—C2	117.34 (14)	O1ⁱⁱ—Li2—N1ⁱⁱ	77.56 (12)
C3—N1—Li2ⁱ	136.14 (14)	O3ⁱⁱⁱ—Li2—N1ⁱⁱ	92.34 (14)
C2—N1—Li2ⁱ	106.51 (13)	O5—Li2—N1ⁱⁱ	97.38 (14)
C4—N2—C5	117.17 (15)	O6—Li2—N1ⁱⁱ	173.18 (17)
N1—C2—C5	121.12 (14)	O7—Li1—O2	105.65 (18)
N1—C2—C1	115.90 (13)	O7—Li1—O6ⁱⁱⁱ	101.58 (17)
C5—C2—C1	122.89 (13)	O2—Li1—O6ⁱⁱⁱ	118.14 (18)
N2—C5—C2	120.88 (14)	O7—Li1—O5	101.05 (17)
N2—C5—C6	115.78 (13)	O2—Li1—O5	110.05 (17)
C2—C5—C6	123.27 (13)	O6ⁱⁱⁱ—Li1—O5	117.60 (17)
N2—C4—C3	121.58 (16)	Li1—O7—H7A	130 (3)
N2—C4—H4	119.2	Li1—O7—H7B	115 (2)
C3—C4—H4	119.2	H7A—O7—H7B	109 (3)

C3—N1—C2—C5	−3.5 (2)	C5—C2—C1—O2	6.1 (2)
Li2ⁱ—N1—C2—C5	176.03 (15)	Li2ⁱⁱⁱ—O3—C6—O4	174.97 (19)
C3—N1—C2—C1	173.33 (16)	Li2ⁱⁱⁱ—O3—C6—C5	−7.5 (3)
Li2ⁱ—N1—C2—C1	−7.18 (18)	N2—C5—C6—O4	73.8 (2)
C4—N2—C5—C2	−4.0 (3)	C2—C5—C6—O4	−109.25 (19)
C4—N2—C5—C6	172.98 (16)	N2—C5—C6—O3	−103.86 (18)
N1—C2—C5—N2	6.5 (3)	C2—C5—C6—O3	73.1 (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—O3ⁱⁱⁱ	1.3 (2)
C1—C2—C5—C6	13.2 (2)	Li1—O5—Li2—O6	88.83 (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—O1ⁱⁱ	105.93 (16)
Li2ⁱ—N1—C3—C4	179.05 (19)	Li1ⁱⁱⁱ—O6—Li2—O3ⁱⁱⁱ	−20.53 (16)
N2—C4—C3—N1	4.1 (3)	Li1ⁱⁱⁱ—O6—Li2—O5	−132.46 (14)
Li2ⁱ—O1—C1—O2	176.24 (17)	C1—O2—Li1—O7	−101.2 (2)
Li2ⁱ—O1—C1—C2	0.7 (2)	C1—O2—Li1—O6ⁱⁱⁱ	11.5 (3)
Li1—O2—C1—O1	87.8 (3)	C1—O2—Li1—O5	150.45 (16)
Li1—O2—C1—C2	−96.7 (2)	Li2—O5—Li1—O7	91.67 (18)
N1—C2—C1—O1	5.3 (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, º) top

D—H···A	D—H	H···A	D···A	D—H···A
O5—H5A···O2^iv	0.81 (3)	1.92 (3)	2.723 (3)	172.60 (3)
O5—H5B···O4	0.87 (4)	2.28 (4)	3.068 (3)	152 (3)
O6—H6A···N2^v	0.86 (3)	2.00 (3)	2.857 (3)	169.66 (4)
O6—H6B···O3	0.88 (3)	1.86 (3)	2.719 (3)	163 (3)
O7—H7A···O4^iv	0.88 (4)	2.02 (4)	2.841 (3)	154.89 (6)
O7—H7B···O4^vi	0.88 (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.

Experimental details

Crystal data
Chemical formula	[Li₂(C₆H₂N₂O₄)(H₂O)₃]
M_r	234.02
Crystal system, space group	Monoclinic, P2₁/c
Temperature (K)	298
a, b, c (Å)	7.487 (3), 16.409 (8), 7.958 (2)
β (°)	92.92 (3)
V (Å³)	976.4 (7)
Z	4
Radiation type	Mo Kα
µ (mm⁻¹)	0.14
Crystal size (mm)	0.4 × 0.2 × 0.06

Data collection
Diffractometer	Rigaku diffractometer
Absorption correction	ψ scan (North et al., 1968)
T_min, T_max	0.948, 0.994
No. of measured, independent and observed [I > 2σ(I)] reflections	6366, 6045, 2427
R_int	0.120
(sin θ/λ)_max (Å⁻¹)	0.904

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.062, 0.211, 0.96
No. of reflections	6045
No. of parameters	178
H-atom treatment	H atoms treated by a mixture of independent and constrained refinement
Δρ_max, Δρ_min (e Å⁻³)	0.49, −0.54

Computer programs: MSC/AFC Diffractometer Control Software (Molecular Structure Corporation, 1989), TEXSAN (Molecular Structure Corporation, 1993), SHELXS97 (Sheldrick, 2008), SHELXL97 (Sheldrick, 2008), Mercury (Macrae et al., 2008), publCIF (Westrip, 2009).

Selected bond lengths (Å) top

O5—Li1	2.046 (4)	Li2—O1ⁱⁱ	1.942 (3)
O5—Li2	2.069 (4)	Li2—O3ⁱⁱⁱ	1.988 (3)
O6—Li2	2.129 (4)	Li2—N1ⁱⁱ	2.317 (4)
O2—Li1	1.927 (3)	Li1—O7	1.918 (4)
N1—Li2ⁱ	2.317 (4)	Li1—O6ⁱⁱⁱ	1.973 (4)

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, º) top

D—H···A	D—H	H···A	D···A	D—H···A
O5—H5A···O2^iv	0.81 (3)	1.92 (3)	2.723 (3)	172.60 (3)
O5—H5B···O4	0.87 (4)	2.28 (4)	3.068 (3)	152 (3)
O6—H6A···N2^v	0.86 (3)	2.00 (3)	2.857 (3)	169.66 (4)
O6—H6B···O3	0.88 (3)	1.86 (3)	2.719 (3)	163 (3)
O7—H7A···O4^iv	0.88 (4)	2.02 (4)	2.841 (3)	154.89 (6)
O7—H7B···O4^vi	0.88 (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.

Acknowledgements

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

References

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