Diaqua­bis­(5-carb­oxy-1H-imidazole-4-carboxyl­ato-κ² N ³,O ⁴)iron(II)

Abstract

In the title compound, [Fe(C₅H₃N₂O₄)₂(H₂O)₂], the Fe^II ion lies on an inversion centre and is coordinated by two N and two O atoms from two 5-carb­oxy-1H-imidazole-4-carboxyl­ate ligands and two water mol­ecules in a distorted octa­hedral geometry. An intra­molecular O—H⋯O hydrogen bond occurs. In the crystal, inter­molecular N—H⋯O and O—H⋯O hydrogen bonds form a three-dimensional network, which consolidates the packing.

Related literature

For the diversity of coordination architectures of the metal atom in complexes with 4,5-dicarb­oxy­imidazole, see: Shimizu et al. (2004 ▶); Fang & Zhang (2006 ▶). For the closely related crystal structures of the Zn, Mg and Cd complexes, see: Ma et al. (2003 ▶), Liu et al. (2004 ▶) and Zhang et al. (2004 ▶), respectively.

Experimental

Crystal data

• [Fe(C₅H₃N₂O₄)₂(H₂O)₂]

• M _r = 402.07

• Monoclinic,

• a = 5.0676 (9) Å

• b = 22.769 (4) Å

• c = 6.6725 (9) Å

• β = 113.733 (10)°

• V = 704.8 (2) ų

• Z = 2

• Mo Kα radiation

• μ = 1.14 mm⁻¹

• T = 298 K

• 0.32 × 0.28 × 0.25 mm

Data collection

• Bruker SMART APEXII CCD area-detector diffractometer

• Absorption correction: multi-scan (SADABS; Bruker, 2005 ▶) T _min = 0.712, T _max = 0.764

• 2872 measured reflections

• 1240 independent reflections

• 976 reflections with I > 2σ(I)

• R _int = 0.027

Refinement

• R[F ² > 2σ(F ²)] = 0.034

• wR(F ²) = 0.080

• S = 1.05

• 1240 reflections

• 116 parameters

• H-atom parameters constrained

• Δρ_max = 0.25 e Å⁻³

• Δρ_min = −0.25 e Å⁻³

Data collection: APEX2 (Bruker, 2005 ▶); cell refinement: SAINT (Bruker, 2005 ▶); data reduction: SAINT; program(s) used to solve structure: SHELXTL (Sheldrick, 2008 ▶); program(s) used to refine structure: SHELXTL; molecular graphics: SHELXTL; software used to prepare material for publication: SHELXTL.

Supplementary Material

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
N2—H2⋯O3i	0.86	2.05	2.897 (3)	169
O3—H3⋯O2	0.82	1.74	2.525 (3)	160
O1W—H1W⋯O2ii	0.85	1.94	2.744 (3)	157
O1W—H2W⋯O1iii	0.85	1.92	2.710 (3)	155

Symmetry codes: (i) ; (ii) ; (iii) .

supplementary crystallographic information

Comment

In recent years, the construction of metal complexes based on 1H-imidazole-4,5-dicarboxylic acid ligand has been investigated in terms of their intriguing topologies. The diversity of coordination architecture of metal 4,5-dicarboxyimidazole has been described by Shimizu et al. (2004) and Fang et al. (2006). In order to search for new metal complexes based on 1H-imidazole-4,5-dicarboxylic acid ligand, the title complex (I) has been synthesized and its crystal determined.

The crystal structure of (I) is isostructural with the previously reported Zn (Ma et al., 2003), Mg (Zhang et al., 2004) and Cd (Liu et al., 2004) 4,5-dicarboxyimidazole complexes. In the four isostructural complexes, all metal ions lie on an inversion centre being coordinated by two N,O-bidentate 1H-imidazole-4,5-dicarboxylate monoanionic ligands and two water molecules in a distorted octahedral geometry.

In the crystal structure of (I), intermolecular N—H···O and O—H···O hydrogen bonds (Table 1) form three-dimensional hydrogen-bonding network, which consolidate the crystal packing.

Experimental

A mixture of FeSO₄^.7H₂O (0.10 mmol), 1H-imidazole-4,5-dicarboxylic acid (0.10 mmol), Et₃N (0.1 ml), EtOH (2 ml) and H₂O (2 ml) was sealed in a 10 ml Tefon-lined stainless-steel reactor and then heated to 393 K for 48 h under autogenous pressure, and then slowly cooled to room temperature at a rate of 5 K/h. Pale-yellow block crystals of the title complex were isolated, washed with distilled water, and dried in air (yield: 48%).

Refinement

H atoms attached to C and N atoms were placed in calculated positions (C—H = 0.93 Å, N—H = 0.86 Å) and refined as riding atoms and with U_iso(H) = 1.2 U_eq(C, N),respectively. The carboxy and water H atoms were located in a difference map, but placed in idealized positions (O—H = 0.82, 0.85 Å), and refined as riding with U_iso(H) = 1.5 U_eq(O).

Figures

Fig. 1.

The molecular structure of (I), with displacement ellipsoids drawn at the 40% probability level [symmetry code: (A) 2 - x, 2 - y, 1 - z].

Crystal data

[Fe(C5H3N2O4)2(H2O)2]	F(000) = 408
Mr = 402.07	Dx = 1.895 Mg m−3
Monoclinic, P21/c	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ybc	Cell parameters from 1102 reflections
a = 5.0676 (9) Å	θ = 3.5–23.7°
b = 22.769 (4) Å	µ = 1.14 mm−1
c = 6.6725 (9) Å	T = 298 K
β = 113.733 (10)°	Block, pale-yellow
V = 704.8 (2) Å3	0.32 × 0.28 × 0.25 mm
Z = 2

Data collection

Bruker SMART APEXII CCD area-detector diffractometer	1240 independent reflections
Radiation source: fine-focus sealed tube	976 reflections with I > 2σ(I)
graphite	Rint = 0.027
φ and ω scans	θmax = 25.2°, θmin = 3.5°
Absorption correction: multi-scan (SADABS; Bruker, 2005)	h = −6→5
Tmin = 0.712, Tmax = 0.764	k = −26→26
2872 measured reflections	l = −4→7

Refinement

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)] = 0.034	Hydrogen site location: inferred from neighbouring sites
wR(F2) = 0.080	H-atom parameters constrained
S = 1.05	w = 1/[σ2(Fo2) + (0.0375P)2 + 0.0621P] where P = (Fo2 + 2Fc2)/3
1240 reflections	(Δ/σ)max < 0.001
116 parameters	Δρmax = 0.25 e Å−3
0 restraints	Δρmin = −0.25 e Å−3

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 (Ų)

	x	y	z	Uiso*/Ueq
C1	1.2587 (6)	0.86826 (13)	0.4808 (4)	0.0322 (7)
H1	1.4476	0.8718	0.5837	0.039*
C2	0.8201 (6)	0.88774 (11)	0.2661 (4)	0.0265 (6)
C3	0.8639 (6)	0.82984 (12)	0.2373 (4)	0.0279 (6)
C4	0.5611 (5)	0.92523 (12)	0.1742 (4)	0.0268 (6)
C5	0.6789 (7)	0.78182 (14)	0.1066 (5)	0.0369 (7)
Fe1	1.0000	1.0000	0.5000	0.0278 (2)
N1	1.0693 (5)	0.91158 (10)	0.4203 (3)	0.0289 (6)
N2	1.1435 (5)	0.81868 (10)	0.3749 (4)	0.0335 (6)
H2	1.2302	0.7855	0.3906	0.040*
O1	0.5823 (4)	0.97682 (8)	0.2452 (3)	0.0313 (5)
O2	0.3337 (4)	0.90334 (9)	0.0295 (3)	0.0370 (5)
O3	0.4133 (4)	0.79590 (9)	−0.0221 (3)	0.0462 (6)
H3	0.3975	0.8318	−0.0301	0.069*
O4	0.7646 (5)	0.73195 (9)	0.1211 (4)	0.0515 (6)
O1W	0.8685 (4)	0.96305 (9)	0.7355 (3)	0.0392 (5)
H1W	1.0038	0.9508	0.8520	0.059*
H2W	0.7663	0.9851	0.7785	0.059*

Atomic displacement parameters (Ų)

	U11	U22	U33	U12	U13	U23
C1	0.0267 (15)	0.0259 (17)	0.0363 (16)	0.0013 (13)	0.0045 (12)	−0.0015 (13)
C2	0.0257 (15)	0.0223 (16)	0.0300 (14)	−0.0002 (12)	0.0098 (12)	0.0011 (12)
C3	0.0274 (16)	0.0224 (16)	0.0320 (15)	0.0013 (13)	0.0101 (12)	0.0011 (12)
C4	0.0259 (16)	0.0258 (18)	0.0268 (14)	0.0010 (12)	0.0088 (12)	0.0022 (12)
C5	0.0379 (18)	0.0283 (18)	0.0430 (18)	−0.0011 (15)	0.0144 (14)	−0.0057 (14)
Fe1	0.0267 (3)	0.0203 (3)	0.0314 (3)	0.0024 (3)	0.0067 (2)	−0.0026 (2)
N1	0.0271 (13)	0.0217 (13)	0.0331 (12)	0.0008 (11)	0.0073 (10)	−0.0030 (10)
N2	0.0316 (14)	0.0218 (14)	0.0432 (14)	0.0079 (11)	0.0110 (11)	0.0020 (11)
O1	0.0282 (11)	0.0220 (11)	0.0375 (11)	0.0047 (9)	0.0068 (9)	−0.0019 (9)
O2	0.0277 (11)	0.0317 (12)	0.0402 (11)	0.0007 (10)	0.0018 (9)	0.0000 (9)
O3	0.0367 (12)	0.0286 (13)	0.0570 (14)	−0.0070 (10)	0.0019 (10)	−0.0073 (11)
O4	0.0512 (15)	0.0258 (13)	0.0703 (16)	−0.0008 (11)	0.0169 (12)	−0.0131 (11)
O1W	0.0346 (12)	0.0437 (14)	0.0385 (11)	0.0168 (10)	0.0140 (9)	0.0092 (10)

Geometric parameters (Å, °)

C1—N1	1.321 (3)	C5—O3	1.312 (3)
C1—N2	1.335 (3)	Fe1—O1Wi	2.1128 (19)
C1—H1	0.9300	Fe1—O1W	2.1128 (19)
C2—C3	1.363 (4)	Fe1—N1	2.147 (2)
C2—N1	1.379 (3)	Fe1—N1i	2.147 (2)
C2—C4	1.476 (4)	Fe1—O1	2.1801 (18)
C3—N2	1.367 (3)	Fe1—O1i	2.1801 (18)
C3—C5	1.475 (4)	N2—H2	0.8600
C4—O1	1.255 (3)	O3—H3	0.8200
C4—O2	1.270 (3)	O1W—H1W	0.8498
C5—O4	1.206 (3)	O1W—H2W	0.8499
N1—C1—N2	111.1 (2)	O1Wi—Fe1—O1	90.82 (7)
N1—C1—H1	124.4	O1W—Fe1—O1	89.18 (7)
N2—C1—H1	124.4	N1—Fe1—O1	77.53 (8)
C3—C2—N1	109.5 (2)	N1i—Fe1—O1	102.47 (8)
C3—C2—C4	132.0 (2)	O1Wi—Fe1—O1i	89.18 (7)
N1—C2—C4	118.4 (2)	O1W—Fe1—O1i	90.82 (7)
C2—C3—N2	105.6 (2)	N1—Fe1—O1i	102.47 (8)
C2—C3—C5	134.4 (2)	N1i—Fe1—O1i	77.53 (7)
N2—C3—C5	120.0 (2)	O1—Fe1—O1i	179.999 (1)
O1—C4—O2	124.6 (2)	C1—N1—C2	105.6 (2)
O1—C4—C2	117.2 (2)	C1—N1—Fe1	142.71 (18)
O2—C4—C2	118.2 (2)	C2—N1—Fe1	111.22 (17)
O4—C5—O3	121.6 (3)	C1—N2—C3	108.2 (2)
O4—C5—C3	121.9 (3)	C1—N2—H2	125.9
O3—C5—C3	116.5 (3)	C3—N2—H2	125.9
O1Wi—Fe1—O1W	179.998 (1)	C4—O1—Fe1	115.45 (16)
O1Wi—Fe1—N1	93.27 (8)	C5—O3—H3	109.5
O1W—Fe1—N1	86.73 (8)	Fe1—O1W—H1W	115.5
O1Wi—Fe1—N1i	86.73 (8)	Fe1—O1W—H2W	115.7
O1W—Fe1—N1i	93.27 (8)	H1W—O1W—H2W	105.2
N1—Fe1—N1i	179.999 (1)
N1—C2—C3—N2	−0.4 (3)	O1Wi—Fe1—N1—C1	96.8 (3)
C4—C2—C3—N2	−176.4 (3)	O1W—Fe1—N1—C1	−83.2 (3)
N1—C2—C3—C5	176.3 (3)	O1—Fe1—N1—C1	−173.1 (3)
C4—C2—C3—C5	0.3 (5)	O1i—Fe1—N1—C1	6.9 (3)
C3—C2—C4—O1	174.6 (3)	O1Wi—Fe1—N1—C2	−93.03 (18)
N1—C2—C4—O1	−1.1 (4)	O1W—Fe1—N1—C2	86.97 (18)
C3—C2—C4—O2	−5.5 (4)	O1—Fe1—N1—C2	−2.91 (16)
N1—C2—C4—O2	178.8 (2)	O1i—Fe1—N1—C2	177.09 (16)
C2—C3—C5—O4	−174.3 (3)	N1—C1—N2—C3	0.1 (3)
N2—C3—C5—O4	1.9 (5)	C2—C3—N2—C1	0.2 (3)
C2—C3—C5—O3	3.9 (5)	C5—C3—N2—C1	−177.1 (3)
N2—C3—C5—O3	−179.8 (3)	O2—C4—O1—Fe1	178.5 (2)
N2—C1—N1—C2	−0.3 (3)	C2—C4—O1—Fe1	−1.6 (3)
N2—C1—N1—Fe1	170.2 (2)	O1Wi—Fe1—O1—C4	95.72 (19)
C3—C2—N1—C1	0.4 (3)	O1W—Fe1—O1—C4	−84.28 (19)
C4—C2—N1—C1	177.0 (2)	N1—Fe1—O1—C4	2.55 (18)
C3—C2—N1—Fe1	−173.45 (18)	N1i—Fe1—O1—C4	−177.45 (18)
C4—C2—N1—Fe1	3.2 (3)

Symmetry codes: (i) −x+2, −y+2, −z+1.

Hydrogen-bond geometry (Å, °)

D—H···A	D—H	H···A	D···A	D—H···A
N2—H2···O3ii	0.86	2.05	2.897 (3)	169
O3—H3···O2	0.82	1.74	2.525 (3)	160
O1W—H1W···O2iii	0.85	1.94	2.744 (3)	157
O1W—H2W···O1iv	0.85	1.92	2.710 (3)	155

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