Diaqua­bis­(4-carb­oxy-2-ethyl-1H-imidazole-5-carboxyl­ato-κ2N3,O4)cadmium dihydrate

Zhang, G.; Wang, Y.

doi:10.1107/S1600536811021428

metal-organic compounds

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ISSN: 2056-9890

Volume 67| Part 7| July 2011| Page m890

doi:10.1107/S1600536811021428

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Diaquabis(4-carboxy-2-ethyl-1H-imidazole-5-carboxylato-κ²N³,O⁴)cadmium dihydrate

Gang Zhang ^a ^* and Yong Wang ^b

^aDepartment of Chemistry and Chemical Engineering, Henan University of Urban Construction, Pingdingshan, Henan, People's Republic of China, and ^bDepartment of Chemical Engineering, Henan Polytechnic Institute, Nanyang 473009, People's Republic of China
^*Correspondence e-mail: zhanghn1010@163.com

(Received 18 May 2011; accepted 3 June 2011; online 11 June 2011)

The asymmetric unit of the title compound, [Cd(C₇H₇N₂O₄)₂(H₂O)₂]·2H₂O, consists of one Cd^II ion, one 4-carboxy-2-ethyl-1H-imidazole-5-carboxylate anion, one coordinated water molecule and one lattice water molecule. The Cd^II ion lies on a twofold axis, and is hexacoordinated by four O atoms from water molecules and carboxylate groups and two N atoms from two imidazole rings, in a distorted octahedral arrangement. An extensive framework of N—H⋯O and O—H⋯O hydrogen bonds with the participation of coordinated and free water molecules is found in the crystal structure, which contributes to the formation of a three-dimensional structure.

Related literature

For coordination polymers built up from related imidazole–carboxylate ligands, see: Li et al. (2011 ); Wang et al. (2008 ); Zhang et al. (2010 ); Tian et al. (2010 ). For a related Cd^II complex based on the ligand 5-carboxy-2-methyl-1H-imidazole-4-carboxylate, see: Nie et al. (2007 ).

Experimental

Crystal data

[Cd(C₇H₇N₂O₄)₂(H₂O)₂]·2H₂O
M_r = 550.76
Monoclinic, C 2/c
a = 9.844 (2) Å
b = 17.084 (3) Å
c = 12.855 (3) Å
β = 102.21 (3)°
V = 2113.0 (8) Å³
Z = 4
Mo Kα radiation
μ = 1.10 mm⁻¹
T = 293 K
0.30 × 0.25 × 0.18 mm

Data collection

Bruker SMART 1000 CCD area-detector diffractometer
Absorption correction: multi-scan (SADABS; Bruker, 2004 ) T_min = 0.733, T_max = 0.826
8379 measured reflections
1898 independent reflections
1560 reflections with I > 2σ(I)
R_int = 0.042

Refinement

R[F² > 2σ(F²)] = 0.028
wR(F²) = 0.072
S = 1.23
1898 reflections
142 parameters
6 restraints
H-atom parameters constrained
Δρ_max = 0.77 e Å⁻³
Δρ_min = −0.78 e Å⁻³

Table 1
Hydrogen-bond geometry (Å, °)

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
O3—H3⋯O2	0.81	1.66	2.468 (4)	172
O2W—H4W⋯O4	0.84	2.16	2.904 (4)	147
O2W—H3W⋯O1ⁱ	0.84	2.08	2.874 (4)	157
O1W—H1W⋯O2ⁱ	0.84	1.97	2.788 (4)	165
O1W—H2W⋯O1ⁱⁱ	0.84	2.01	2.768 (3)	150
N1—H9⋯O2Wⁱⁱⁱ	0.91	1.86	2.771 (4)	177
Symmetry codes: (i) $[-x+{\script{1\over 2}}, -y+{\script{1\over 2}}, -z]$ ; (ii) x-1, y, z; (iii) $[x+{\script{1\over 2}}, y-{\script{1\over 2}}, z]$ .

Data collection: SMART (Bruker, 2004); cell refinement: SAINT (Bruker, 2004); data reduction: SAINT; 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/S1600536811021428/bh2359sup1.cif

Structure factors: contains datablock I. DOI: 10.1107/S1600536811021428/bh2359Isup2.hkl

checkCIF report

Comment top

Self-assembly of supramolecular architectures based on imidazole carboxylate ligands has draw much attention during recent decades. To the best of our knowledge, coordination polymers based on 2-ethyl-4,5-imidazolecarboxylate have been rarely reported so far (Wang et al., 2008; Zhang et al., 2010; Li et al., 2011; Tian et al., 2010). Herein we report the synthesis of the title compound by the reaction of cadmium nitrate with 2-ethyl-4,5-imidazoledicarboxylic acid (H₃EIDC) in an aqueous solution under hydrothermal conditions, and its crystal structure.

The title compound, [Cd(C₇H₇N₂O₄)₂(H₂O)₂].2H₂O, differs from the Cd(II) complex based on the similar ligand 5-carboxy-2- methyl-1H-imidazole-4-carboxylate, where the Cd(II) ion is six-coordinated in a centrosymmetric arrangement (Nie et al., 2007). As depicted in Fig. 1, the title complex has two symmetrical coordination water molecules, two interstitial water molecules and two 4-carboxy-2-ethyl-1H-imidazole-5-carboxylate ligands (H₂EIDC). The Cd(II), placed on a 2-fold axis, is surrounded by two terminal water molecules, two N atoms and two O atoms from two different H₂EIDC ligands, forming a distorted octahedral coordination environment.

One solvent water molecule completes the asymmetric unit, and forms hydrogen bonds with the imidazole N atom (N1), the carboxylic O atom (O4) and the O atom from the coordinated water molecule (O1W), whose distances and angles are shown in Table 1. Each H₂EIDC ligand is bonded to Cd(II) ion in a chelating mode. A three-dimensional supramolecular structure is consolidated by intermolecular hydrogen-bonding (N—H···O and O—H···O) and intramolecular hydrogen-bonding O—H···O.

Related literature top

For coordination polymers built up from related imidazolecarboxylate ligands, see: Li et al. (2011); Wang et al. (2008); Zhang et al. (2010); Tian et al. (2010). For a related Cd^II complex based on the ligand 5-carboxy-2- methyl-1H-imidazole-4-carboxylate, see: Nie et al. (2007).

Experimental top

A mixture of Cd(NO₃)₂ (0.5 mmol, 0.120 g) and 2-ethyl-1H-imidazole-4,5-dicarboxylic acid (0.5 mmol, 0.95 g) in 15 ml of H₂O solution was placed in a 23 ml Teflon-lined reactor, which was heated to 423 K for 2 days, and then cooled to room temperature at a rate of 10 K h^-1. Crystals of the title compound were obtained by slow evaporation of the solvent at room temperature.

Computing details top

Data collection: SMART (Bruker, 2004); cell refinement: SAINT (Bruker, 2004); data reduction: SAINT (Bruker, 2004); 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 (Sheldrick, 2008).

Figures top

Fig. 1. The structure of the title compound, showing the atomic numbering scheme with 30% probability displacement ellipsoids [Symmetry codes i: -x, y, 1/2-z].

Diaquabis(4-carboxy-2-ethyl-1H-imidazole-5-carboxylato- κ²N³,O⁴)cadmium dihydrate top

Crystal data top

[Cd(C₇H₇N₂O₄)₂(H₂O)₂]·2H₂O	F(000) = 1112
M_r = 550.76	D_x = 1.731 Mg m⁻³
Monoclinic, C2/c	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -C 2yc	Cell parameters from 1702 reflections
a = 9.844 (2) Å	θ = 2.5–25.9°
b = 17.084 (3) Å	µ = 1.10 mm⁻¹
c = 12.855 (3) Å	T = 293 K
β = 102.21 (3)°	Block, colourless
V = 2113.0 (8) Å³	0.30 × 0.25 × 0.18 mm
Z = 4

Data collection top

Bruker SMART 1000 CCD area-detector diffractometer	1898 independent reflections
Radiation source: fine-focus sealed tube	1560 reflections with I > 2σ(I)
Graphite monochromator	R_int = 0.042
ϕ and ω scans	θ_max = 25.2°, θ_min = 3.2°
Absorption correction: multi-scan (SADABS; Bruker, 2004)	h = −11→10
T_min = 0.733, T_max = 0.826	k = −20→20
8379 measured reflections	l = −15→15

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)] = 0.028	Hydrogen site location: inferred from neighbouring sites
wR(F²) = 0.072	H-atom parameters constrained
S = 1.23	w = 1/[σ²(F_o²) + (0.0164P)² + 5.0177P] where P = (F_o² + 2F_c²)/3
1898 reflections	(Δ/σ)_max < 0.001
142 parameters	Δρ_max = 0.77 e Å⁻³
6 restraints	Δρ_min = −0.78 e Å⁻³
0 constraints

Crystal data top

[Cd(C₇H₇N₂O₄)₂(H₂O)₂]·2H₂O	V = 2113.0 (8) Å³
M_r = 550.76	Z = 4
Monoclinic, C2/c	Mo Kα radiation
a = 9.844 (2) Å	µ = 1.10 mm⁻¹
b = 17.084 (3) Å	T = 293 K
c = 12.855 (3) Å	0.30 × 0.25 × 0.18 mm
β = 102.21 (3)°

Data collection top

Bruker SMART 1000 CCD area-detector diffractometer	1898 independent reflections
Absorption correction: multi-scan (SADABS; Bruker, 2004)	1560 reflections with I > 2σ(I)
T_min = 0.733, T_max = 0.826	R_int = 0.042
8379 measured reflections

Refinement top

R[F² > 2σ(F²)] = 0.028	6 restraints
wR(F²) = 0.072	H-atom parameters constrained
S = 1.23	Δρ_max = 0.77 e Å⁻³
1898 reflections	Δρ_min = −0.78 e Å⁻³
142 parameters

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

	x	y	z	U_iso*/U_eq
Cd1	0.0000	0.20278 (3)	0.2500	0.03340 (14)
O1	0.5880 (2)	0.14665 (16)	0.0777 (2)	0.0399 (7)
O2	0.5052 (3)	0.26839 (16)	0.0774 (2)	0.0439 (7)
O3	0.3063 (3)	0.33738 (16)	0.1245 (2)	0.0470 (7)
H3	0.3668	0.3140	0.1034	0.071*
O4	0.1229 (2)	0.30656 (16)	0.1896 (2)	0.0414 (6)
N1	0.3597 (3)	0.08847 (17)	0.1520 (2)	0.0288 (7)
H9	0.4044	0.0442	0.1391	0.035*
N2	0.1837 (3)	0.14937 (18)	0.1946 (2)	0.0287 (7)
C1	0.2678 (3)	0.2036 (2)	0.1605 (2)	0.0244 (7)
C2	0.3782 (3)	0.1654 (2)	0.1332 (3)	0.0266 (8)
C3	0.2420 (3)	0.0805 (2)	0.1895 (3)	0.0311 (8)
C4	0.1894 (4)	0.0046 (3)	0.2202 (4)	0.0506 (11)
H4A	0.2676	−0.0260	0.2578	0.061*
H4B	0.1289	0.0145	0.2693	0.061*
C5	0.1137 (8)	−0.0418 (4)	0.1323 (6)	0.127 (3)
H5A	0.0380	−0.0115	0.0927	0.190*
H5B	0.0780	−0.0880	0.1595	0.190*
H5C	0.1750	−0.0565	0.0867	0.190*
C6	0.5001 (3)	0.1949 (2)	0.0929 (3)	0.0316 (8)
C7	0.2289 (3)	0.2871 (2)	0.1586 (3)	0.0320 (8)
O1W	−0.1380 (3)	0.1871 (2)	0.0846 (2)	0.0691 (11)
H2W	−0.2184	0.1706	0.0594	0.104*
H1W	−0.1026	0.2090	0.0386	0.104*
O2W	−0.0139 (3)	0.45120 (19)	0.1075 (3)	0.0695 (10)
H4W	0.0458	0.4235	0.1478	0.104*
H3W	−0.0307	0.4344	0.0448	0.104*

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
Cd1	0.02313 (19)	0.0344 (3)	0.0474 (2)	0.000	0.01810 (16)	0.000
O1	0.0283 (13)	0.0410 (18)	0.0557 (16)	−0.0001 (12)	0.0208 (12)	−0.0051 (13)
O2	0.0461 (15)	0.0289 (18)	0.0667 (18)	−0.0072 (12)	0.0345 (14)	0.0007 (13)
O3	0.0492 (16)	0.0276 (16)	0.075 (2)	−0.0021 (13)	0.0379 (15)	0.0003 (14)
O4	0.0338 (13)	0.0300 (16)	0.0671 (17)	0.0057 (12)	0.0261 (13)	0.0010 (14)
N1	0.0266 (14)	0.0189 (17)	0.0439 (17)	0.0022 (12)	0.0143 (13)	−0.0014 (13)
N2	0.0244 (14)	0.0242 (18)	0.0404 (16)	−0.0010 (12)	0.0134 (13)	0.0001 (13)
C1	0.0238 (15)	0.0191 (18)	0.0320 (17)	−0.0039 (15)	0.0098 (14)	−0.0003 (15)
C2	0.0210 (15)	0.030 (2)	0.0307 (18)	−0.0007 (14)	0.0088 (14)	−0.0007 (15)
C3	0.0261 (17)	0.028 (2)	0.041 (2)	0.0000 (15)	0.0115 (16)	0.0016 (16)
C4	0.041 (2)	0.032 (3)	0.084 (3)	0.0013 (18)	0.026 (2)	0.013 (2)
C5	0.173 (7)	0.092 (6)	0.123 (6)	−0.090 (6)	0.049 (5)	−0.033 (5)
C6	0.0250 (17)	0.039 (3)	0.0337 (19)	−0.0047 (17)	0.0123 (15)	−0.0069 (18)
C7	0.0298 (17)	0.030 (2)	0.0383 (19)	−0.0029 (16)	0.0123 (16)	0.0000 (17)
O1W	0.0318 (14)	0.134 (4)	0.0430 (16)	−0.0229 (18)	0.0119 (13)	0.0104 (19)
O2W	0.085 (2)	0.049 (2)	0.068 (2)	0.0309 (18)	0.0014 (18)	−0.0144 (17)

Geometric parameters (Å, º) top

Cd1—N2ⁱ	2.270 (3)	N2—C1	1.375 (4)
Cd1—N2	2.270 (3)	C1—C2	1.375 (5)
Cd1—O1W	2.284 (3)	C1—C7	1.476 (5)
Cd1—O1Wⁱ	2.284 (3)	C2—C6	1.491 (5)
Cd1—O4	2.368 (3)	C3—C4	1.481 (5)
Cd1—O4ⁱ	2.368 (3)	C4—C5	1.450 (7)
O1—C6	1.239 (4)	C4—H4A	0.9700
O2—C6	1.275 (5)	C4—H4B	0.9700
O3—C7	1.284 (4)	C5—H5A	0.9600
O3—H3	0.8096	C5—H5B	0.9600
O4—C7	1.239 (4)	C5—H5C	0.9600
N1—C3	1.353 (4)	O1W—H2W	0.8388
N1—C2	1.356 (5)	O1W—H1W	0.8355
N1—H9	0.9080	O2W—H4W	0.8424
N2—C3	1.317 (5)	O2W—H3W	0.8381

N2ⁱ—Cd1—N2	132.60 (15)	N1—C2—C6	122.5 (3)
N2ⁱ—Cd1—O1W	83.59 (10)	C1—C2—C6	131.7 (3)
N2—Cd1—O1W	91.00 (11)	N2—C3—N1	110.1 (3)
N2ⁱ—Cd1—O1Wⁱ	91.00 (11)	N2—C3—C4	126.1 (3)
N2—Cd1—O1Wⁱ	83.59 (10)	N1—C3—C4	123.9 (3)
O1W—Cd1—O1Wⁱ	166.5 (2)	C5—C4—C3	114.9 (4)
N2ⁱ—Cd1—O4	154.13 (10)	C5—C4—H4A	108.5
N2—Cd1—O4	72.67 (10)	C3—C4—H4A	108.5
O1W—Cd1—O4	91.54 (10)	C5—C4—H4B	108.5
O1Wⁱ—Cd1—O4	98.55 (11)	C3—C4—H4B	108.5
N2ⁱ—Cd1—O4ⁱ	72.67 (10)	H4A—C4—H4B	107.5
N2—Cd1—O4ⁱ	154.13 (10)	C4—C5—H5A	109.5
O1W—Cd1—O4ⁱ	98.55 (11)	C4—C5—H5B	109.5
O1Wⁱ—Cd1—O4ⁱ	91.54 (10)	H5A—C5—H5B	109.5
O4—Cd1—O4ⁱ	83.03 (12)	C4—C5—H5C	109.5
C7—O3—H3	108.4	H5A—C5—H5C	109.5
C7—O4—Cd1	115.4 (2)	H5B—C5—H5C	109.5
C3—N1—C2	108.6 (3)	O1—C6—O2	125.3 (3)
C3—N1—H9	117.7	O1—C6—C2	118.1 (4)
C2—N1—H9	133.5	O2—C6—C2	116.6 (3)
C3—N2—C1	106.7 (3)	O4—C7—O3	122.1 (4)
C3—N2—Cd1	139.4 (2)	O4—C7—C1	119.1 (3)
C1—N2—Cd1	113.7 (2)	O3—C7—C1	118.8 (3)
N2—C1—C2	108.9 (3)	Cd1—O1W—H2W	136.5
N2—C1—C7	119.0 (3)	Cd1—O1W—H1W	110.6
C2—C1—C7	132.1 (3)	H2W—O1W—H1W	112.2
N1—C2—C1	105.8 (3)	H4W—O2W—H3W	111.6

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
O3—H3···O2	0.81	1.66	2.468 (4)	172
O2W—H4W···O4	0.84	2.16	2.904 (4)	147
O2W—H3W···O1ⁱⁱ	0.84	2.08	2.874 (4)	157
O1W—H1W···O2ⁱⁱ	0.84	1.97	2.788 (4)	165
O1W—H2W···O1ⁱⁱⁱ	0.84	2.01	2.768 (3)	150
N1—H9···O2W^iv	0.91	1.86	2.771 (4)	177

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

Experimental details

Crystal data
Chemical formula	[Cd(C₇H₇N₂O₄)₂(H₂O)₂]·2H₂O
M_r	550.76
Crystal system, space group	Monoclinic, C2/c
Temperature (K)	293
a, b, c (Å)	9.844 (2), 17.084 (3), 12.855 (3)
β (°)	102.21 (3)
V (Å³)	2113.0 (8)
Z	4
Radiation type	Mo Kα
µ (mm⁻¹)	1.10
Crystal size (mm)	0.30 × 0.25 × 0.18

Data collection
Diffractometer	Bruker SMART 1000 CCD area-detector diffractometer
Absorption correction	Multi-scan (SADABS; Bruker, 2004)
T_min, T_max	0.733, 0.826
No. of measured, independent and observed [I > 2σ(I)] reflections	8379, 1898, 1560
R_int	0.042
(sin θ/λ)_max (Å⁻¹)	0.599

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.028, 0.072, 1.23
No. of reflections	1898
No. of parameters	142
No. of restraints	6
H-atom treatment	H-atom parameters constrained
Δρ_max, Δρ_min (e Å⁻³)	0.77, −0.78

Computer programs: SMART (Bruker, 2004), SAINT (Bruker, 2004), SHELXS97 (Sheldrick, 2008), SHELXL97 (Sheldrick, 2008), SHELXTL (Sheldrick, 2008).

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
O3—H3···O2	0.81	1.66	2.468 (4)	171.8
O2W—H4W···O4	0.84	2.16	2.904 (4)	146.6
O2W—H3W···O1ⁱ	0.84	2.08	2.874 (4)	157.2
O1W—H1W···O2ⁱ	0.84	1.97	2.788 (4)	164.5
O1W—H2W···O1ⁱⁱ	0.84	2.01	2.768 (3)	149.8
N1—H9···O2Wⁱⁱⁱ	0.91	1.86	2.771 (4)	176.5

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

Acknowledgements

The authors acknowledge Henan University of Urban Construction for supporting this work.

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