trans-Diaqua­bis[5-carb­oxy-4-carboxyl­ato-2-(4-pyridinio)-1H-imidazol-1-ido-κ2N3,O4]iron(II)

Li, X.; Liu, W.; Wu, B.-L.; Zhang, H.-Y.

doi:10.1107/S160053680902337X

metal-organic compounds

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ISSN: 2056-9890

Volume 65| Part 7| July 2009| Pages m820-m821

doi:10.1107/S160053680902337X

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trans-Diaquabis[5-carboxy-4-carboxylato-2-(4-pyridinio)-1H-imidazol-1-ido-κ²N³,O⁴]iron(II)

Xia Li,^a Wei Liu,^a Ben-Lai Wu ^b and Hong-Yun Zhang ^b ^*

^aDepartment of Chemistry and Chemical Engineering, Pingdingshan Engineering College, Pingdingshan, Henan, 467001, People's Republic of China, and ^bDepartment of Chemistry, Zhengzhou University, Zhengzhou, Henan, 450052, People's Republic of China
^*Correspondence e-mail: lixia@zzu.edu.cn, wzhy917@zzu.edu.cn

(Received 28 April 2009; accepted 17 June 2009; online 24 June 2009)

In the title complex, [Fe(C₁₀H₆N₃O₄)₂(H₂O)₂], the Fe^II atom is located on a twofold rotation axis and is coordinated by two trans-positioned N,O-bidentate and zwitterionic 5-carboxy-2-(pyridinium-4-yl)-1H-imidazol-1-ide-4-carboxylate H₂PIDC⁻ ligands and two water molecules in a distorted environment. In the crystal packing, a three-dimensional network is constructed via hydrogen-bonding involving the water molecules, uncoordinated imidazole N atom, protonated pyridine N and carboxylate O atoms.

Related literature

For the use of the multifunctional connector 4,5-imidazoledicarboxylic acid (H₃IDC) in coordination chemistry, see: Liu et al. (2004 ); Maji et al. (2005 ); Plieger et al. (2005 ); Rajendiran et al. (2003 ); Zou et al. (2005 ). For the preparation of 2-(pyridin-4-yl)-1H-imidazole-4,5-dicarboxylic acid, see: Sun et al. (2006 ).

Experimental

Crystal data

[Fe(C₁₀H₆N₃O₄)₂(H₂O)₂]
M_r = 556.24
Monoclinic, C 2/c
a = 21.344 (4) Å
b = 7.3900 (15) Å
c = 13.768 (3) Å
β = 104.70 (3)°
V = 2100.6 (7) Å³
Z = 4
Mo Kα radiation
μ = 0.80 mm⁻¹
T = 173 K
0.25 × 0.15 × 0.12 mm

Data collection

Rigaku Mercury CCD diffractometer
Absorption correction: multi-scan (CrystalClear; Rigaku, 2000 ) T_min = 0.870, T_max = 0.921
8952 measured reflections
2386 independent reflections
2083 reflections with I > 2σ(I)
R_int = 0.021

Refinement

R[F² > 2σ(F²)] = 0.029
wR(F²) = 0.079
S = 1.04
2386 reflections
175 parameters
H atoms treated by a mixture of independent and constrained refinement
Δρ_max = 0.37 e Å⁻³
Δρ_min = −0.25 e Å⁻³

Table 1
Selected bond lengths (Å)

Fe1—O6	2.081 (2)
Fe1—O1	2.1087 (13)
Fe1—O7	2.121 (2)
Fe1—N1	2.2311 (14)

Table 2
Hydrogen-bond geometry (Å, °)

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
O6—H6⋯N2ⁱ	0.86 (2)	2.04 (2)	2.8806 (18)	169 (3)
N3—H3⋯O2ⁱⁱ	0.88	1.99	2.707 (2)	138
O3—H3B⋯O2	0.99	1.53	2.4959 (19)	166
Symmetry codes: (i) $[x, -y, z-{\script{1\over 2}}]$ ; (ii) $[x+{\script{1\over 2}}, -y+{\script{1\over 2}}, z+{\script{1\over 2}}]$ .

Data collection: CrystalClear (Rigaku, 2000); cell refinement: CrystalClear; data reduction: CrystalClear; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 ); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: SHELXTL (Sheldrick, 2008); software used to prepare material for publication: SHELXTL.

Supporting information

Crystal structure: contains datablocks I, global. DOI: 10.1107/S160053680902337X/kp2221sup1.cif

Structure factors: contains datablock I. DOI: 10.1107/S160053680902337X/kp2221Isup2.hkl

checkCIF report

Comment top

Multifunctional connector 4,5-imidazoledicarboxylic acid (H₃IDC), adjusting its existing forms and coordination modes through pH or temperature in assembly reaction systems, shows more interesting traits in the construction of nano-structures and MOFs, and thus has been extensively investigated in coordination chemistry (Maji et al., 2005; Liu et al., 2004; Zou et al., 2005; Rajendiran et al., 2003; Plieger et al., 2005). 2-(Pyridin-4-yl)-1H-imidazole-4,5-dicarboxylate acid (H₃PIDC), a close analogue of H₃IDC, is endowed a promising building block H₃IDC and the additional pyridine group modulate coordination ability to give more potential coordination modes and enlarge conjugation system. In order to explore the coordination chemistry of this ligand, we have isolated a new Fe^II complex, [Fe(H₂PIDC)₂(H₂O)₂], (I), by the reaction of H₃PIDC and Fe^II sulfate under the hydrothermal condition. We report here the single-crystal structure of this complex.

The molecule of (I) is a discrete neutral monomer (Fig. 1) in which the Fe atom resides on a twofold rotation axes and the asymmetric unit comprises a half of the [Fe(H₂PIDC)₂(H₂O)₂] formula unit. Each Fe atom is hexacoordinated by N₂O₄ with two chelating rings from two H₂PIDC ligands arranged symmetrically in the equatorial plane and two water molecules occupying the apical sites, defining an octahedral coordination (Table 1). In this complex, a carboxyl group and imidazole group are deprotonated and the pyridyl group is protonated, and the ligand bears a formal charge of -1. The free carboxylate atoms O3 and O2 form an intramolecular hydrogen bond (Table 2). All non-H atoms in the imidazole-4,5-dicarboxyl group are nearly coplanar [the mean deviation is 0.025 (4) Å], and the dihedral angle between imidazole group and pyridine group is 10.3 (2)°.

The hydrogen bonding involves the water molecules, uncoordinated imidazole N atom, protonated pyridine N and carboxylate O atoms (Table 2 and Fig. 2).

Related literature top

For the use of the multifunctional connector 4,5-imidazoledicarboxylic acid (H₃IDC) in coordination chemistry, see: Liu et al. (2004); Maji et al. (2005); Plieger et al. (2005); Rajendiran et al. (2003);Zou et al. (2005). For the preparation of 2-(pyridin-4-yl)-1H-imidazole-4,5-dicarboxylic acid, see: Sun et al. (2006).

Experimental top

A mixture of Fe^II sulfate (0.028 g, 0.1 mmol), 2-(pyridin-4-yl)-1H-imidazole-4,5-dicarboxylic acid (0.024 g, 0.1 mmol) (Sun et al., 2006), NaOH (0.004 g, 0.1 mmol) and H2O (10 ml) was sealed into a Teflon-lined stainless autoclave and heated at 423 K for 3 d, then cooled to room temperature gradually and red block crystals of (I) were obtained.

Computing details top

Data collection: CrystalClear (Rigaku, 2000); cell refinement: CrystalClear (Rigaku, 2000); data reduction: CrystalClear (Rigaku, 2000); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: SHELXL97 (Sheldrick, 2008); software used to prepare material for publication: SHELXTL (Sheldrick, 2008).

Figures top

	Fig. 1. A view of the complex of (I) showing the atom-labelling scheme and displacement ellipsoids at the 30% probability level.
	Fig. 2. The crystal packing of (I) showing the three-dimensional hydrogen-bonding network; H atoms not involved in hydrogen bonding have been omited.

trans-Diaquabis[5-carboxy-4-carboxylato-2-(4-pyridinio)-1H- imidazol-1-ido-κ²N³,O⁴]iron(II) top

Crystal data top

[Fe(C₁₀H₆N₃O₄)₂(H₂O)₂]	F(000) = 1136
M_r = 556.24	D_x = 1.759 Mg m⁻³
Monoclinic, C2/c	Mo Kα radiation, λ = 0.71073 Å
a = 21.344 (4) Å	θ = 2.9–28.3°
b = 7.3900 (15) Å	µ = 0.80 mm⁻¹
c = 13.768 (3) Å	T = 173 K
β = 104.70 (3)°	Block, red
V = 2100.6 (7) Å³	0.25 × 0.15 × 0.12 mm
Z = 4

Data collection top

Mercury CCD diffractometer	2386 independent reflections
Radiation source: fine-focus sealed tube	2083 reflections with I > 2σ(I)
Graphite monochromator	R_int = 0.021
ω scans	θ_max = 27.5°, θ_min = 2.9°
Absorption correction: multi-scan (CrystalClear; Rigaku, 2000)	h = −27→27
T_min = 0.870, T_max = 0.921	k = −9→9
8952 measured reflections	l = −17→17

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)] = 0.029	Hydrogen site location: inferred from neighbouring sites
wR(F²) = 0.079	H atoms treated by a mixture of independent and constrained refinement
S = 1.04	w = 1/[σ²(F_o²) + (0.0388P)² + 2.1264P] where P = (F_o² + 2F_c²)/3
2386 reflections	(Δ/σ)_max < 0.001
175 parameters	Δρ_max = 0.37 e Å⁻³
0 restraints	Δρ_min = −0.25 e Å⁻³

Crystal data top

[Fe(C₁₀H₆N₃O₄)₂(H₂O)₂]	V = 2100.6 (7) Å³
M_r = 556.24	Z = 4
Monoclinic, C2/c	Mo Kα radiation
a = 21.344 (4) Å	µ = 0.80 mm⁻¹
b = 7.3900 (15) Å	T = 173 K
c = 13.768 (3) Å	0.25 × 0.15 × 0.12 mm
β = 104.70 (3)°

Data collection top

Mercury CCD diffractometer	2386 independent reflections
Absorption correction: multi-scan (CrystalClear; Rigaku, 2000)	2083 reflections with I > 2σ(I)
T_min = 0.870, T_max = 0.921	R_int = 0.021
8952 measured reflections

Refinement top

R[F² > 2σ(F²)] = 0.029	0 restraints
wR(F²) = 0.079	H atoms treated by a mixture of independent and constrained refinement
S = 1.04	Δρ_max = 0.37 e Å⁻³
2386 reflections	Δρ_min = −0.25 e Å⁻³
175 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
Fe1	0.0000	0.19391 (5)	0.2500	0.02067 (11)
O1	−0.10126 (6)	0.20613 (19)	0.22910 (9)	0.0309 (3)
O2	−0.17764 (6)	0.3056 (2)	0.29923 (10)	0.0391 (4)
O3	−0.18924 (6)	0.3890 (2)	0.46949 (10)	0.0406 (4)
H3B	−0.1867	0.3754	0.3994	0.061*
O4	−0.12932 (7)	0.3875 (2)	0.62503 (10)	0.0452 (4)
O6	0.0000	−0.0877 (3)	0.2500	0.0352 (5)
N1	−0.00912 (6)	0.21688 (19)	0.40741 (10)	0.0203 (3)
N2	−0.01854 (7)	0.2842 (2)	0.56415 (10)	0.0236 (3)
N3	0.21933 (7)	0.1542 (2)	0.63905 (12)	0.0341 (4)
H3	0.2608	0.1397	0.6677	0.051*
C1	0.19580 (9)	0.1005 (3)	0.54346 (14)	0.0334 (4)
H1	0.2237	0.0464	0.5079	0.040*
C2	0.18128 (9)	0.2296 (3)	0.69186 (14)	0.0360 (5)
H2	0.1994	0.2653	0.7595	0.043*
C3	0.11686 (9)	0.2556 (3)	0.64969 (13)	0.0308 (4)
H3A	0.0903	0.3092	0.6877	0.037*
C4	0.13117 (8)	0.1242 (3)	0.49733 (13)	0.0281 (4)
H4	0.1144	0.0871	0.4296	0.034*
C5	0.09009 (8)	0.2030 (2)	0.55010 (12)	0.0220 (3)
C6	0.02077 (8)	0.2333 (2)	0.50603 (12)	0.0210 (3)
C7	−0.07755 (8)	0.3048 (2)	0.49880 (12)	0.0215 (3)
C8	−0.13379 (8)	0.3626 (3)	0.53665 (13)	0.0272 (4)
C9	−0.07183 (7)	0.2631 (2)	0.40239 (12)	0.0205 (3)
C10	−0.11994 (8)	0.2578 (2)	0.30365 (12)	0.0244 (4)
O7	0.0000	0.4810 (3)	0.2500	0.0340 (4)
H6	−0.0101 (12)	−0.153 (3)	0.1969 (18)	0.051*
H7	0.0223 (11)	0.530 (4)	0.2972 (17)	0.051*

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
Fe1	0.01809 (17)	0.0276 (2)	0.01644 (17)	0.000	0.00460 (12)	0.000
O1	0.0218 (6)	0.0513 (8)	0.0176 (6)	−0.0004 (6)	0.0017 (5)	−0.0067 (5)
O2	0.0155 (6)	0.0730 (11)	0.0251 (7)	0.0076 (6)	−0.0012 (5)	−0.0053 (6)
O3	0.0198 (6)	0.0712 (10)	0.0312 (7)	0.0084 (6)	0.0071 (5)	−0.0069 (7)
O4	0.0391 (8)	0.0752 (11)	0.0249 (7)	0.0073 (8)	0.0144 (6)	−0.0062 (7)
O6	0.0571 (13)	0.0273 (10)	0.0212 (9)	0.000	0.0096 (9)	0.000
N1	0.0154 (6)	0.0279 (7)	0.0162 (6)	0.0011 (5)	0.0016 (5)	0.0006 (5)
N2	0.0188 (7)	0.0338 (8)	0.0170 (7)	−0.0013 (6)	0.0023 (5)	0.0005 (6)
N3	0.0156 (7)	0.0524 (10)	0.0296 (8)	0.0029 (7)	−0.0026 (6)	0.0055 (7)
C1	0.0236 (9)	0.0457 (11)	0.0315 (10)	0.0055 (8)	0.0079 (7)	0.0021 (8)
C2	0.0238 (9)	0.0558 (13)	0.0231 (9)	−0.0022 (8)	−0.0038 (7)	−0.0021 (8)
C3	0.0217 (9)	0.0473 (11)	0.0215 (9)	−0.0002 (8)	0.0022 (7)	−0.0035 (8)
C4	0.0224 (8)	0.0391 (10)	0.0212 (8)	0.0019 (7)	0.0025 (7)	0.0008 (7)
C5	0.0173 (8)	0.0277 (9)	0.0190 (8)	−0.0009 (6)	0.0013 (6)	0.0039 (6)
C6	0.0179 (8)	0.0274 (8)	0.0161 (7)	−0.0003 (6)	0.0015 (6)	0.0017 (6)
C7	0.0179 (7)	0.0285 (9)	0.0177 (7)	−0.0015 (6)	0.0035 (6)	−0.0004 (6)
C8	0.0230 (8)	0.0360 (10)	0.0235 (8)	−0.0004 (7)	0.0080 (7)	−0.0019 (7)
C9	0.0151 (7)	0.0280 (8)	0.0174 (8)	0.0003 (6)	0.0020 (6)	0.0005 (6)
C10	0.0173 (8)	0.0347 (9)	0.0189 (8)	−0.0013 (7)	0.0004 (6)	−0.0005 (7)
O7	0.0447 (12)	0.0303 (10)	0.0206 (9)	0.000	−0.0033 (8)	0.000

Geometric parameters (Å, º) top

Fe1—O6	2.081 (2)	N3—C2	1.341 (3)
Fe1—O1	2.1087 (13)	N3—C1	1.344 (2)
Fe1—O1ⁱ	2.1087 (13)	N3—H3	0.8793
Fe1—O7	2.121 (2)	C1—C4	1.376 (2)
Fe1—N1	2.2311 (14)	C1—H1	0.9500
Fe1—N1ⁱ	2.2311 (14)	C2—C3	1.364 (3)
O1—C10	1.251 (2)	C2—H2	0.9500
O2—C10	1.268 (2)	C3—C5	1.400 (2)
O3—C8	1.318 (2)	C3—H3A	0.9500
O3—H3B	0.9857	C4—C5	1.399 (2)
O4—C8	1.210 (2)	C4—H4	0.9500
O6—H6	0.86 (2)	C5—C6	1.467 (2)
N1—C6	1.351 (2)	C7—C9	1.398 (2)
N1—C9	1.366 (2)	C7—C8	1.488 (2)
N2—C6	1.352 (2)	C9—C10	1.482 (2)
N2—C7	1.358 (2)	O7—H7	0.79 (2)

O6—Fe1—O1	92.45 (4)	N3—C2—C3	120.77 (17)
O6—Fe1—O1ⁱ	92.45 (4)	N3—C2—H2	119.6
O1—Fe1—O1ⁱ	175.09 (8)	C3—C2—H2	119.6
O6—Fe1—O7	180.0	C2—C3—C5	119.65 (18)
O1—Fe1—O7	87.55 (4)	C2—C3—H3A	120.2
O1ⁱ—Fe1—O7	87.55 (4)	C5—C3—H3A	120.2
O6—Fe1—N1	94.36 (4)	C1—C4—C5	120.01 (16)
O1—Fe1—N1	77.89 (5)	C1—C4—H4	120.0
O1ⁱ—Fe1—N1	101.73 (6)	C5—C4—H4	120.0
O7—Fe1—N1	85.64 (4)	C4—C5—C3	118.05 (15)
O6—Fe1—N1ⁱ	94.36 (4)	C4—C5—C6	123.22 (15)
O1—Fe1—N1ⁱ	101.73 (6)	C3—C5—C6	118.73 (15)
O1ⁱ—Fe1—N1ⁱ	77.89 (5)	N1—C6—N2	114.46 (14)
O7—Fe1—N1ⁱ	85.64 (4)	N1—C6—C5	124.85 (15)
N1—Fe1—N1ⁱ	171.27 (7)	N2—C6—C5	120.68 (14)
C10—O1—Fe1	115.47 (11)	N2—C7—C9	108.34 (14)
C8—O3—H3B	114.1	N2—C7—C8	119.69 (14)
Fe1—O6—H6	124.1 (17)	C9—C7—C8	131.97 (15)
C6—N1—C9	103.60 (13)	O4—C8—O3	120.70 (17)
C6—N1—Fe1	147.96 (11)	O4—C8—C7	122.08 (16)
C9—N1—Fe1	107.20 (10)	O3—C8—C7	117.21 (15)
C6—N2—C7	104.46 (13)	N1—C9—C7	109.12 (14)
C2—N3—C1	121.75 (16)	N1—C9—C10	118.80 (14)
C2—N3—H3	119.1	C7—C9—C10	132.06 (15)
C1—N3—H3	119.2	O1—C10—O2	123.61 (15)
N3—C1—C4	119.76 (17)	O1—C10—C9	118.02 (15)
N3—C1—H1	120.1	O2—C10—C9	118.37 (15)
C4—C1—H1	120.1	Fe1—O7—H7	117.2 (19)

O6—Fe1—O1—C10	108.54 (13)	C7—N2—C6—N1	−0.9 (2)
O1ⁱ—Fe1—O1—C10	−71.46 (13)	C7—N2—C6—C5	178.14 (15)
O7—Fe1—O1—C10	−71.46 (13)	C4—C5—C6—N1	−11.1 (3)
N1—Fe1—O1—C10	14.60 (13)	C3—C5—C6—N1	168.70 (17)
N1ⁱ—Fe1—O1—C10	−156.48 (13)	C4—C5—C6—N2	169.95 (17)
O6—Fe1—N1—C6	92.7 (2)	C3—C5—C6—N2	−10.3 (3)
O1—Fe1—N1—C6	−175.7 (2)	C6—N2—C7—C9	0.63 (19)
O1ⁱ—Fe1—N1—C6	−0.7 (2)	C6—N2—C7—C8	−179.49 (16)
O7—Fe1—N1—C6	−87.3 (2)	N2—C7—C8—O4	−2.2 (3)
N1ⁱ—Fe1—N1—C6	−87.3 (2)	C9—C7—C8—O4	177.7 (2)
O6—Fe1—N1—C9	−103.82 (10)	N2—C7—C8—O3	176.82 (16)
O1—Fe1—N1—C9	−12.24 (11)	C9—C7—C8—O3	−3.3 (3)
O1ⁱ—Fe1—N1—C9	162.76 (11)	C6—N1—C9—C7	−0.38 (18)
O7—Fe1—N1—C9	76.18 (10)	Fe1—N1—C9—C7	−171.43 (11)
N1ⁱ—Fe1—N1—C9	76.18 (10)	C6—N1—C9—C10	−179.12 (15)
C2—N3—C1—C4	0.6 (3)	Fe1—N1—C9—C10	9.83 (18)
C1—N3—C2—C3	−0.4 (3)	N2—C7—C9—N1	−0.2 (2)
N3—C2—C3—C5	0.0 (3)	C8—C7—C9—N1	179.98 (17)
N3—C1—C4—C5	−0.4 (3)	N2—C7—C9—C10	178.35 (17)
C1—C4—C5—C3	0.0 (3)	C8—C7—C9—C10	−1.5 (3)
C1—C4—C5—C6	179.77 (17)	Fe1—O1—C10—O2	166.15 (15)
C2—C3—C5—C4	0.2 (3)	Fe1—O1—C10—C9	−13.9 (2)
C2—C3—C5—C6	−179.60 (18)	N1—C9—C10—O1	1.9 (2)
C9—N1—C6—N2	0.84 (19)	C7—C9—C10—O1	−176.46 (18)
Fe1—N1—C6—N2	164.57 (16)	N1—C9—C10—O2	−178.12 (16)
C9—N1—C6—C5	−178.20 (16)	C7—C9—C10—O2	3.5 (3)
Fe1—N1—C6—C5	−14.5 (3)

Symmetry code: (i) −x, y, −z+1/2.

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
O6—H6···N2ⁱⁱ	0.86 (2)	2.04 (2)	2.8806 (18)	169 (3)
N3—H3···O2ⁱⁱⁱ	0.88	1.99	2.707 (2)	138
O3—H3B···O2	0.99	1.53	2.4959 (19)	166

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

Experimental details

Crystal data
Chemical formula	[Fe(C₁₀H₆N₃O₄)₂(H₂O)₂]
M_r	556.24
Crystal system, space group	Monoclinic, C2/c
Temperature (K)	173
a, b, c (Å)	21.344 (4), 7.3900 (15), 13.768 (3)
β (°)	104.70 (3)
V (Å³)	2100.6 (7)
Z	4
Radiation type	Mo Kα
µ (mm⁻¹)	0.80
Crystal size (mm)	0.25 × 0.15 × 0.12

Data collection
Diffractometer	Mercury CCD diffractometer
Absorption correction	Multi-scan (CrystalClear; Rigaku, 2000)
T_min, T_max	0.870, 0.921
No. of measured, independent and observed [I > 2σ(I)] reflections	8952, 2386, 2083
R_int	0.021
(sin θ/λ)_max (Å⁻¹)	0.649

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.029, 0.079, 1.04
No. of reflections	2386
No. of parameters	175
H-atom treatment	H atoms treated by a mixture of independent and constrained refinement
Δρ_max, Δρ_min (e Å⁻³)	0.37, −0.25

Computer programs: CrystalClear (Rigaku, 2000), SHELXS97 (Sheldrick, 2008), SHELXL97 (Sheldrick, 2008), SHELXTL (Sheldrick, 2008).

Selected bond lengths (Å) top

Fe1—O6	2.081 (2)	Fe1—O7	2.121 (2)
Fe1—O1	2.1087 (13)	Fe1—N1	2.2311 (14)

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
O6—H6···N2ⁱ	0.86 (2)	2.04 (2)	2.8806 (18)	169 (3)
N3—H3···O2ⁱⁱ	0.88	1.99	2.707 (2)	137.8
O3—H3B···O2	0.99	1.53	2.4959 (19)	165.5

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

Acknowledgements

This work was supported by the National Natural Science Foundation of China (20771094, 20671083), the Science and Technology Key Task of Henan Province (0524270061) and the China Postdoctoral Science Foundation (20070410877).

References

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