metal-organic compounds\(\def\hfill{\hskip 5em}\def\hfil{\hskip 3em}\def\eqno#1{\hfil {#1}}\)

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ISSN: 2056-9890

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

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 CdII ion, one 4-carb­oxy-2-ethyl-1H-imidazole-5-carboxyl­ate anion, one coordinated water mol­ecule and one lattice water mol­ecule. The CdII 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[Li, S.-J., Ma, X.-T., Song, W.-D., Li, X.-F. & Liu, J.-H. (2011). Acta Cryst. E67, m295-m296.]); Wang et al. (2008[Wang, S., Zhang, L. R., Li, G. H., Huo, Q. S. & Liu, Y. L. (2008). CrystEngComm, 10, 1662-1666.]); Zhang et al. (2010[Zhang, F. W., Li, Z. F., Ge, T. Z., Yao, H. C., Li, G., Lu, H. J. & Zhu, Y. Y. (2010). Inorg. Chem. 49, 3776-3788.]); Tian et al. (2010[Tian, D.-M., Li, Y.-F. & Hao, C.-J. (2010). Z. Kristallogr. New Cryst. Struct. 225, 403-404.]). For a related CdII complex based on the ligand 5-carb­oxy-2-methyl-1H-imidazole-4-carboxyl­ate, see: Nie et al. (2007[Nie, X.-L., Wen, H.-L., Wu, Z.-S., Liu, D.-B. & Liu, C.-B. (2007). Acta Cryst. E63, m753-m755.]).

[Scheme 1]

Experimental

Crystal data
  • [Cd(C7H7N2O4)2(H2O)2]·2H2O

  • Mr = 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[Bruker (2004). SMART, SAINT and SADABS. Bruker AXS Inc., Madison, Wisconsin, USA.]) Tmin = 0.733, Tmax = 0.826

  • 8379 measured reflections

  • 1898 independent reflections

  • 1560 reflections with I > 2σ(I)

  • Rint = 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

  • Δρmax = 0.77 e Å−3

  • Δρmin = −0.78 e Å−3

Table 1
Hydrogen-bond geometry (Å, °)

D—H⋯A D—H H⋯A DA 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[Bruker (2004). SMART, SAINT and SADABS. Bruker AXS Inc., Madison, Wisconsin, USA.]); cell refinement: SAINT (Bruker, 2004[Bruker (2004). SMART, SAINT and SADABS. Bruker AXS Inc., Madison, Wisconsin, USA.]); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008[Sheldrick, G. M. (2008). Acta Cryst. A64, 112-122.]); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008[Sheldrick, G. M. (2008). Acta Cryst. A64, 112-122.]); molecular graphics: SHELXTL (Sheldrick, 2008[Sheldrick, G. M. (2008). Acta Cryst. A64, 112-122.]); software used to prepare material for publication: SHELXTL.

Supporting information


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 CdII 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.

Refinement top

The carboxyl H atom H3 was located in a difference map but refined as riding on the parent O atom with O3—H3 = 0.81 Å and Uiso(H3) = 1.5 Ueq(O3). Carbon and nitrogen bound H atoms were placed at calculated positions and were treated as riding on the parent C or N atoms with C—H = 0.96 (methyl), 0.97 (methylene) and N—H = 0.91 Å, Uiso(H) = 1.2 or 1.5 Ueq(C, N). H atoms of the water molecules were located in a difference Fourier map and refined as riding with the O—H bond lengths fixed to their as-found values and Uiso(H) = 1.5 Ueq(carrier O).

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
[Figure 1] 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]·2H2OF(000) = 1112
Mr = 550.76Dx = 1.731 Mg m3
Monoclinic, C2/cMo Kα radiation, λ = 0.71073 Å
Hall symbol: -C 2ycCell parameters from 1702 reflections
a = 9.844 (2) Åθ = 2.5–25.9°
b = 17.084 (3) ŵ = 1.10 mm1
c = 12.855 (3) ÅT = 293 K
β = 102.21 (3)°Block, colourless
V = 2113.0 (8) Å30.30 × 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 tube1560 reflections with I > 2σ(I)
Graphite monochromatorRint = 0.042
ϕ and ω scansθmax = 25.2°, θmin = 3.2°
Absorption correction: multi-scan
(SADABS; Bruker, 2004)
h = 1110
Tmin = 0.733, Tmax = 0.826k = 2020
8379 measured reflectionsl = 1515
Refinement top
Refinement on F2Primary atom site location: structure-invariant direct methods
Least-squares matrix: fullSecondary atom site location: difference Fourier map
R[F2 > 2σ(F2)] = 0.028Hydrogen site location: inferred from neighbouring sites
wR(F2) = 0.072H-atom parameters constrained
S = 1.23 w = 1/[σ2(Fo2) + (0.0164P)2 + 5.0177P]
where P = (Fo2 + 2Fc2)/3
1898 reflections(Δ/σ)max < 0.001
142 parametersΔρmax = 0.77 e Å3
6 restraintsΔρmin = 0.78 e Å3
0 constraints
Crystal data top
[Cd(C7H7N2O4)2(H2O)2]·2H2OV = 2113.0 (8) Å3
Mr = 550.76Z = 4
Monoclinic, C2/cMo Kα radiation
a = 9.844 (2) ŵ = 1.10 mm1
b = 17.084 (3) ÅT = 293 K
c = 12.855 (3) Å0.30 × 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)
Tmin = 0.733, Tmax = 0.826Rint = 0.042
8379 measured reflections
Refinement top
R[F2 > 2σ(F2)] = 0.0286 restraints
wR(F2) = 0.072H-atom parameters constrained
S = 1.23Δρmax = 0.77 e Å3
1898 reflectionsΔρmin = 0.78 e Å3
142 parameters
Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top
xyzUiso*/Ueq
Cd10.00000.20278 (3)0.25000.03340 (14)
O10.5880 (2)0.14665 (16)0.0777 (2)0.0399 (7)
O20.5052 (3)0.26839 (16)0.0774 (2)0.0439 (7)
O30.3063 (3)0.33738 (16)0.1245 (2)0.0470 (7)
H30.36680.31400.10340.071*
O40.1229 (2)0.30656 (16)0.1896 (2)0.0414 (6)
N10.3597 (3)0.08847 (17)0.1520 (2)0.0288 (7)
H90.40440.04420.13910.035*
N20.1837 (3)0.14937 (18)0.1946 (2)0.0287 (7)
C10.2678 (3)0.2036 (2)0.1605 (2)0.0244 (7)
C20.3782 (3)0.1654 (2)0.1332 (3)0.0266 (8)
C30.2420 (3)0.0805 (2)0.1895 (3)0.0311 (8)
C40.1894 (4)0.0046 (3)0.2202 (4)0.0506 (11)
H4A0.26760.02600.25780.061*
H4B0.12890.01450.26930.061*
C50.1137 (8)0.0418 (4)0.1323 (6)0.127 (3)
H5A0.03800.01150.09270.190*
H5B0.07800.08800.15950.190*
H5C0.17500.05650.08670.190*
C60.5001 (3)0.1949 (2)0.0929 (3)0.0316 (8)
C70.2289 (3)0.2871 (2)0.1586 (3)0.0320 (8)
O1W0.1380 (3)0.1871 (2)0.0846 (2)0.0691 (11)
H2W0.21840.17060.05940.104*
H1W0.10260.20900.03860.104*
O2W0.0139 (3)0.45120 (19)0.1075 (3)0.0695 (10)
H4W0.04580.42350.14780.104*
H3W0.03070.43440.04480.104*
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
Cd10.02313 (19)0.0344 (3)0.0474 (2)0.0000.01810 (16)0.000
O10.0283 (13)0.0410 (18)0.0557 (16)0.0001 (12)0.0208 (12)0.0051 (13)
O20.0461 (15)0.0289 (18)0.0667 (18)0.0072 (12)0.0345 (14)0.0007 (13)
O30.0492 (16)0.0276 (16)0.075 (2)0.0021 (13)0.0379 (15)0.0003 (14)
O40.0338 (13)0.0300 (16)0.0671 (17)0.0057 (12)0.0261 (13)0.0010 (14)
N10.0266 (14)0.0189 (17)0.0439 (17)0.0022 (12)0.0143 (13)0.0014 (13)
N20.0244 (14)0.0242 (18)0.0404 (16)0.0010 (12)0.0134 (13)0.0001 (13)
C10.0238 (15)0.0191 (18)0.0320 (17)0.0039 (15)0.0098 (14)0.0003 (15)
C20.0210 (15)0.030 (2)0.0307 (18)0.0007 (14)0.0088 (14)0.0007 (15)
C30.0261 (17)0.028 (2)0.041 (2)0.0000 (15)0.0115 (16)0.0016 (16)
C40.041 (2)0.032 (3)0.084 (3)0.0013 (18)0.026 (2)0.013 (2)
C50.173 (7)0.092 (6)0.123 (6)0.090 (6)0.049 (5)0.033 (5)
C60.0250 (17)0.039 (3)0.0337 (19)0.0047 (17)0.0123 (15)0.0069 (18)
C70.0298 (17)0.030 (2)0.0383 (19)0.0029 (16)0.0123 (16)0.0000 (17)
O1W0.0318 (14)0.134 (4)0.0430 (16)0.0229 (18)0.0119 (13)0.0104 (19)
O2W0.085 (2)0.049 (2)0.068 (2)0.0309 (18)0.0014 (18)0.0144 (17)
Geometric parameters (Å, º) top
Cd1—N2i2.270 (3)N2—C11.375 (4)
Cd1—N22.270 (3)C1—C21.375 (5)
Cd1—O1W2.284 (3)C1—C71.476 (5)
Cd1—O1Wi2.284 (3)C2—C61.491 (5)
Cd1—O42.368 (3)C3—C41.481 (5)
Cd1—O4i2.368 (3)C4—C51.450 (7)
O1—C61.239 (4)C4—H4A0.9700
O2—C61.275 (5)C4—H4B0.9700
O3—C71.284 (4)C5—H5A0.9600
O3—H30.8096C5—H5B0.9600
O4—C71.239 (4)C5—H5C0.9600
N1—C31.353 (4)O1W—H2W0.8388
N1—C21.356 (5)O1W—H1W0.8355
N1—H90.9080O2W—H4W0.8424
N2—C31.317 (5)O2W—H3W0.8381
N2i—Cd1—N2132.60 (15)N1—C2—C6122.5 (3)
N2i—Cd1—O1W83.59 (10)C1—C2—C6131.7 (3)
N2—Cd1—O1W91.00 (11)N2—C3—N1110.1 (3)
N2i—Cd1—O1Wi91.00 (11)N2—C3—C4126.1 (3)
N2—Cd1—O1Wi83.59 (10)N1—C3—C4123.9 (3)
O1W—Cd1—O1Wi166.5 (2)C5—C4—C3114.9 (4)
N2i—Cd1—O4154.13 (10)C5—C4—H4A108.5
N2—Cd1—O472.67 (10)C3—C4—H4A108.5
O1W—Cd1—O491.54 (10)C5—C4—H4B108.5
O1Wi—Cd1—O498.55 (11)C3—C4—H4B108.5
N2i—Cd1—O4i72.67 (10)H4A—C4—H4B107.5
N2—Cd1—O4i154.13 (10)C4—C5—H5A109.5
O1W—Cd1—O4i98.55 (11)C4—C5—H5B109.5
O1Wi—Cd1—O4i91.54 (10)H5A—C5—H5B109.5
O4—Cd1—O4i83.03 (12)C4—C5—H5C109.5
C7—O3—H3108.4H5A—C5—H5C109.5
C7—O4—Cd1115.4 (2)H5B—C5—H5C109.5
C3—N1—C2108.6 (3)O1—C6—O2125.3 (3)
C3—N1—H9117.7O1—C6—C2118.1 (4)
C2—N1—H9133.5O2—C6—C2116.6 (3)
C3—N2—C1106.7 (3)O4—C7—O3122.1 (4)
C3—N2—Cd1139.4 (2)O4—C7—C1119.1 (3)
C1—N2—Cd1113.7 (2)O3—C7—C1118.8 (3)
N2—C1—C2108.9 (3)Cd1—O1W—H2W136.5
N2—C1—C7119.0 (3)Cd1—O1W—H1W110.6
C2—C1—C7132.1 (3)H2W—O1W—H1W112.2
N1—C2—C1105.8 (3)H4W—O2W—H3W111.6
Symmetry code: (i) x, y, z+1/2.
Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
O3—H3···O20.811.662.468 (4)172
O2W—H4W···O40.842.162.904 (4)147
O2W—H3W···O1ii0.842.082.874 (4)157
O1W—H1W···O2ii0.841.972.788 (4)165
O1W—H2W···O1iii0.842.012.768 (3)150
N1—H9···O2Wiv0.911.862.771 (4)177
Symmetry codes: (ii) x+1/2, y+1/2, z; (iii) x1, y, z; (iv) x+1/2, y1/2, z.

Experimental details

Crystal data
Chemical formula[Cd(C7H7N2O4)2(H2O)2]·2H2O
Mr550.76
Crystal system, space groupMonoclinic, C2/c
Temperature (K)293
a, b, c (Å)9.844 (2), 17.084 (3), 12.855 (3)
β (°) 102.21 (3)
V3)2113.0 (8)
Z4
Radiation typeMo Kα
µ (mm1)1.10
Crystal size (mm)0.30 × 0.25 × 0.18
Data collection
DiffractometerBruker SMART 1000 CCD area-detector
diffractometer
Absorption correctionMulti-scan
(SADABS; Bruker, 2004)
Tmin, Tmax0.733, 0.826
No. of measured, independent and
observed [I > 2σ(I)] reflections
8379, 1898, 1560
Rint0.042
(sin θ/λ)max1)0.599
Refinement
R[F2 > 2σ(F2)], wR(F2), S 0.028, 0.072, 1.23
No. of reflections1898
No. of parameters142
No. of restraints6
H-atom treatmentH-atom parameters constrained
Δρmax, Δρmin (e Å3)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···AD—HH···AD···AD—H···A
O3—H3···O20.811.662.468 (4)171.8
O2W—H4W···O40.842.162.904 (4)146.6
O2W—H3W···O1i0.842.082.874 (4)157.2
O1W—H1W···O2i0.841.972.788 (4)164.5
O1W—H2W···O1ii0.842.012.768 (3)149.8
N1—H9···O2Wiii0.911.862.771 (4)176.5
Symmetry codes: (i) x+1/2, y+1/2, z; (ii) x1, y, z; (iii) x+1/2, y1/2, z.
 

Acknowledgements

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

References

First citationBruker (2004). SMART, SAINT and SADABS. Bruker AXS Inc., Madison, Wisconsin, USA.  Google Scholar
First citationLi, S.-J., Ma, X.-T., Song, W.-D., Li, X.-F. & Liu, J.-H. (2011). Acta Cryst. E67, m295–m296.  Web of Science CSD CrossRef IUCr Journals Google Scholar
First citationNie, X.-L., Wen, H.-L., Wu, Z.-S., Liu, D.-B. & Liu, C.-B. (2007). Acta Cryst. E63, m753–m755.  Web of Science CSD CrossRef IUCr Journals Google Scholar
First citationSheldrick, G. M. (2008). Acta Cryst. A64, 112–122.  Web of Science CrossRef CAS IUCr Journals Google Scholar
First citationTian, D.-M., Li, Y.-F. & Hao, C.-J. (2010). Z. Kristallogr. New Cryst. Struct. 225, 403–404.  CAS Google Scholar
First citationWang, S., Zhang, L. R., Li, G. H., Huo, Q. S. & Liu, Y. L. (2008). CrystEngComm, 10, 1662–1666.  Web of Science CSD CrossRef CAS Google Scholar
First citationZhang, F. W., Li, Z. F., Ge, T. Z., Yao, H. C., Li, G., Lu, H. J. & Zhu, Y. Y. (2010). Inorg. Chem. 49, 3776–3788.  Web of Science CSD CrossRef CAS PubMed Google Scholar

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