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In the title compound, [Cd(C6H6N4)2(H2O)2](C8H4O4), the CdII atom (site symmetry \overline{1}) is chelated by two 2,2′-bi­imidazole (H2biim) ligands in the equatorial plane and two axial water mol­ecules to result in a trans-CdN4O2 octa­hedral geometry. The complex dication and centrosymmetric benzene-1,4-dicarboxyl­ate (bdc) dianion inter­act via O—H...O and N—H...O hydrogen bonds. Centrosymmetric aromatic π–π stacking involving one of the C3N2 rings of the H2biim species also occurs with a short centroid–centroid separation of 3.4164 (14) Å.

Supporting information

cif

Crystallographic Information File (CIF) https://doi.org/10.1107/S160053680703067X/hb2453sup1.cif
Contains datablocks I, global

hkl

Structure factor file (CIF format) https://doi.org/10.1107/S160053680703067X/hb2453Isup2.hkl
Contains datablock I

CCDC reference: 654832

Key indicators

  • Single-crystal X-ray study
  • T = 293 K
  • Mean [sigma](C-C) = 0.002 Å
  • R factor = 0.018
  • wR factor = 0.049
  • Data-to-parameter ratio = 14.2

checkCIF/PLATON results

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Alert level C PLAT250_ALERT_2_C Large U3/U1 Ratio for Average U(i,j) Tensor .... 2.71 PLAT720_ALERT_4_C Number of Unusual/Non-Standard Label(s) ........ 3 PLAT790_ALERT_4_C Centre of Gravity not Within Unit Cell: Resd. # 2 C8 H4 O4
Alert level G PLAT199_ALERT_1_G Check the Reported _cell_measurement_temperature 293 K PLAT200_ALERT_1_G Check the Reported _diffrn_ambient_temperature . 293 K PLAT794_ALERT_5_G Check Predicted Bond Valency for Cd1 (2) 2.13 PLAT860_ALERT_3_G Note: Number of Least-Squares Restraints ....... 4
0 ALERT level A = In general: serious problem 0 ALERT level B = Potentially serious problem 3 ALERT level C = Check and explain 4 ALERT level G = General alerts; check 2 ALERT type 1 CIF construction/syntax error, inconsistent or missing data 1 ALERT type 2 Indicator that the structure model may be wrong or deficient 1 ALERT type 3 Indicator that the structure quality may be low 2 ALERT type 4 Improvement, methodology, query or suggestion 1 ALERT type 5 Informative message, check

Comment top

As part of the ongoing study of complexes containing 2,2'-biimidazole (H2biim) as a ligand (Ding et al.,2005), we now report the title compound, (I), which contains Cd2+-containing complex ions, charge balanced by benzene-1,4-dicarboxylate dianions.

The Cd atom (site symmetry 1) in (I) is coordinated by four N atoms of two H2biim ligands and two O atoms from two water molecules, in a octahedral geometry (Table 1, Fig. 1). The cation and anion interact by way of N—H···O and O—H···O hydrogen bonds (Table 2).

The plane-to-plane distance of 3.26 Å between the C1 imidazol ring and its symmetry equivalent partner at (3 - x, -y, 2 - z), in an offset fashion (slippage = 1.10 Å) indicates a strong ππ interaction (Fig. 2).

Related literature top

For a related structure, see: Ding et al. (2005). For the ligand synthesis, see: Fieselmann et al. (1978). For reference geometrical data, see: Allen et al. (1987).

Experimental top

2,2'-Biimidazole was synthesized according to the literature method (Fieselmann et al., 1978). Benzene-1,4-dicarboxylic acid, 2,2'-biimidazole and cadmium acetate dihydrate were reacted in a molar ratio of 1:2:1. The mixture was stirred for 30 min, then the pH was adjusted to 6.5 with an aqueous solution of NaOH (0.1 M). The mixture with a total volume of 21 ml was heated at 433 K for 5 d in a sealed 25 ml Teflon-lined stainless steel vessel under autogenous pressure. After the reaction mixture was slowly cooled to room temperature at a rate of 5 K h-1, colourless blocks of (I) were obtained.

Refinement top

The water H atoms were located in a difference map and refined as riding in their as-found relative positions with free refinement for their Uiso values. The other H atoms were positioned geometrically (C—H = 0.93 Å, N—H = 0.86 Å) and refined as riding with Uiso(H) = 1.2Ueq(C).

Structure description top

As part of the ongoing study of complexes containing 2,2'-biimidazole (H2biim) as a ligand (Ding et al.,2005), we now report the title compound, (I), which contains Cd2+-containing complex ions, charge balanced by benzene-1,4-dicarboxylate dianions.

The Cd atom (site symmetry 1) in (I) is coordinated by four N atoms of two H2biim ligands and two O atoms from two water molecules, in a octahedral geometry (Table 1, Fig. 1). The cation and anion interact by way of N—H···O and O—H···O hydrogen bonds (Table 2).

The plane-to-plane distance of 3.26 Å between the C1 imidazol ring and its symmetry equivalent partner at (3 - x, -y, 2 - z), in an offset fashion (slippage = 1.10 Å) indicates a strong ππ interaction (Fig. 2).

For a related structure, see: Ding et al. (2005). For the ligand synthesis, see: Fieselmann et al. (1978). For reference geometrical data, see: Allen et al. (1987).

Computing details top

Data collection: SMART (Bruker, 1997); cell refinement: SAINT (Bruker, 1997); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: SHELXTL (Bruker, 1997); software used to prepare material for publication: SHELXL97 and local programs.

Figures top
[Figure 1] Fig. 1. The molecular structure of (I) with displacement ellipsoids drawn at the 30% probability level (arbitrary spheres for the H atoms). Symmetry codes: (i) 2 - x, -y, 2 - z; (ii) 2 - x, -y, 3 - z.
[Figure 2] Fig. 2. The packing diagrame for (I). The dotted lines indicate the hydrogen bonds.
Diaquabis(2,2'-biimidazole)cadmium(II) benzene-1,4-dicarboxylate top
Crystal data top
[Cd(C6H6N4)2(H2O)2](C8H4O4)F(000) = 584
Mr = 580.84Dx = 1.660 Mg m3
Monoclinic, P21/nMo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ynCell parameters from 903 reflections
a = 8.336 (2) Åθ = 2.6–25.8°
b = 11.009 (3) ŵ = 0.99 mm1
c = 12.688 (4) ÅT = 293 K
β = 93.674 (3)°Block, colourless
V = 1161.9 (6) Å30.58 × 0.53 × 0.25 mm
Z = 2
Data collection top
Bruker SMART CCD
diffractometer
2294 independent reflections
Radiation source: fine-focus sealed tube2139 reflections with I > 2σ(I)
Graphite monochromatorRint = 0.014
ω scansθmax = 26.1°, θmin = 2.5°
Absorption correction: multi-scan
(SADABS; Sheldrick, 1996) or Bruker (1997)?
h = 1010
Tmin = 0.596, Tmax = 0.786k = 1313
9682 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)] = 0.018Hydrogen site location: inferred from neighbouring sites
wR(F2) = 0.049H-atom parameters constrained
S = 1.04 w = 1/[σ2(Fo2) + (0.0258P)2 + 0.5043P]
where P = (Fo2 + 2Fc2)/3
2294 reflections(Δ/σ)max = 0.003
162 parametersΔρmax = 0.30 e Å3
4 restraintsΔρmin = 0.26 e Å3
Crystal data top
[Cd(C6H6N4)2(H2O)2](C8H4O4)V = 1161.9 (6) Å3
Mr = 580.84Z = 2
Monoclinic, P21/nMo Kα radiation
a = 8.336 (2) ŵ = 0.99 mm1
b = 11.009 (3) ÅT = 293 K
c = 12.688 (4) Å0.58 × 0.53 × 0.25 mm
β = 93.674 (3)°
Data collection top
Bruker SMART CCD
diffractometer
2294 independent reflections
Absorption correction: multi-scan
(SADABS; Sheldrick, 1996) or Bruker (1997)?
2139 reflections with I > 2σ(I)
Tmin = 0.596, Tmax = 0.786Rint = 0.014
9682 measured reflections
Refinement top
R[F2 > 2σ(F2)] = 0.0184 restraints
wR(F2) = 0.049H-atom parameters constrained
S = 1.04Δρmax = 0.30 e Å3
2294 reflectionsΔρmin = 0.26 e Å3
162 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
xyzUiso*/Ueq
Cd11.00000.00001.00000.02922 (7)
OW11.08556 (16)0.14916 (12)0.87749 (10)0.0465 (3)
HW1A1.13760.12330.82720.058 (7)*
HW1B1.10150.22830.88700.061 (7)*
O20.62681 (16)0.09753 (13)1.35814 (11)0.0526 (4)
O10.72382 (15)0.05438 (15)1.26778 (11)0.0510 (4)
N11.25379 (15)0.08664 (12)1.01642 (10)0.0272 (3)
N21.48489 (15)0.08867 (12)1.11125 (10)0.0289 (3)
H2A1.55910.06981.15870.035*
N31.34980 (16)0.12255 (13)1.23815 (11)0.0352 (3)
H3A1.44480.10881.26610.042*
N41.13014 (16)0.10607 (13)1.13365 (10)0.0321 (3)
C80.8710 (2)0.00788 (13)1.42460 (14)0.0297 (4)
C70.7303 (2)0.01824 (15)1.34368 (14)0.0340 (4)
C91.0192 (2)0.03370 (17)1.39653 (14)0.0342 (4)
H91.03260.05671.32710.041*
C31.33955 (18)0.03673 (14)1.09696 (12)0.0249 (3)
C11.3500 (2)0.17504 (15)0.97813 (13)0.0322 (3)
H11.32220.22570.92120.039*
C101.1479 (2)0.04125 (17)1.47141 (13)0.0340 (4)
H101.24710.06881.45180.041*
C41.27572 (18)0.06208 (14)1.15733 (12)0.0264 (3)
C21.4928 (2)0.17705 (15)1.03637 (14)0.0336 (4)
H21.57910.22861.02700.040*
C61.1112 (2)0.19951 (17)1.20294 (15)0.0414 (4)
H61.02020.24811.20520.050*
C51.2461 (2)0.20980 (19)1.26767 (15)0.0436 (4)
H51.26440.26581.32200.052*
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
Cd10.02300 (10)0.03417 (11)0.02907 (10)0.00073 (6)0.00917 (7)0.00343 (6)
OW10.0536 (8)0.0415 (8)0.0455 (8)0.0030 (6)0.0117 (6)0.0052 (6)
O20.0464 (8)0.0513 (8)0.0563 (8)0.0186 (7)0.0271 (7)0.0148 (7)
O10.0353 (7)0.0740 (10)0.0412 (8)0.0118 (7)0.0167 (6)0.0207 (7)
N10.0257 (6)0.0282 (7)0.0270 (6)0.0006 (5)0.0036 (5)0.0018 (5)
N20.0227 (6)0.0315 (7)0.0316 (7)0.0014 (5)0.0058 (5)0.0000 (5)
N30.0281 (7)0.0417 (8)0.0340 (7)0.0040 (6)0.0115 (6)0.0114 (6)
N40.0261 (7)0.0364 (8)0.0326 (7)0.0045 (6)0.0061 (5)0.0080 (6)
C80.0278 (8)0.0277 (8)0.0321 (9)0.0017 (6)0.0102 (7)0.0019 (6)
C70.0297 (9)0.0391 (9)0.0317 (9)0.0003 (7)0.0104 (7)0.0007 (7)
C90.0327 (9)0.0412 (9)0.0277 (8)0.0006 (7)0.0057 (7)0.0021 (7)
C30.0231 (7)0.0254 (7)0.0258 (7)0.0006 (6)0.0023 (6)0.0019 (6)
C10.0343 (8)0.0297 (8)0.0322 (8)0.0014 (7)0.0002 (7)0.0057 (6)
C100.0265 (8)0.0398 (9)0.0346 (9)0.0031 (7)0.0052 (7)0.0013 (7)
C40.0244 (7)0.0290 (8)0.0251 (7)0.0000 (6)0.0043 (6)0.0017 (6)
C20.0315 (8)0.0297 (8)0.0397 (9)0.0055 (6)0.0023 (7)0.0025 (7)
C60.0348 (9)0.0444 (10)0.0440 (10)0.0117 (8)0.0062 (8)0.0160 (8)
C50.0415 (10)0.0463 (10)0.0412 (10)0.0083 (8)0.0100 (8)0.0216 (8)
Geometric parameters (Å, º) top
Cd1—N42.2759 (14)N3—H3A0.8600
Cd1—N4i2.2759 (14)N4—C41.323 (2)
Cd1—N1i2.3178 (14)N4—C61.369 (2)
Cd1—N12.3178 (14)C8—C91.385 (3)
Cd1—OW12.4007 (14)C8—C10ii1.388 (3)
Cd1—OW1i2.4007 (14)C8—C71.513 (2)
OW1—HW1A0.8438C9—C101.389 (2)
OW1—HW1B0.8879C9—H90.9300
O2—C71.249 (2)C3—C41.451 (2)
O1—C71.250 (2)C1—C21.360 (2)
N1—C31.328 (2)C1—H10.9300
N1—C11.370 (2)C10—C8ii1.388 (3)
N2—C31.341 (2)C10—H100.9300
N2—C21.364 (2)C2—H20.9300
N2—H2A0.8600C6—C51.354 (2)
N3—C41.340 (2)C6—H60.9300
N3—C51.361 (2)C5—H50.9300
N4—Cd1—N4i180.0C9—C8—C10ii119.26 (16)
N4—Cd1—N1i104.16 (5)C9—C8—C7121.05 (16)
N4i—Cd1—N1i75.84 (5)C10ii—C8—C7119.68 (16)
N4—Cd1—N175.84 (5)O2—C7—O1124.34 (16)
N4i—Cd1—N1104.16 (5)O2—C7—C8117.75 (16)
N1i—Cd1—N1180.0O1—C7—C8117.90 (16)
N4—Cd1—OW189.10 (5)C8—C9—C10120.43 (17)
N4i—Cd1—OW190.90 (5)C8—C9—H9119.8
N1i—Cd1—OW188.15 (5)C10—C9—H9119.8
N1—Cd1—OW191.85 (5)N1—C3—N2111.39 (14)
N4—Cd1—OW1i90.90 (5)N1—C3—C4121.26 (13)
N4i—Cd1—OW1i89.10 (5)N2—C3—C4127.35 (14)
N1i—Cd1—OW1i91.85 (5)C2—C1—N1109.33 (14)
N1—Cd1—OW1i88.15 (5)C2—C1—H1125.3
OW1—Cd1—OW1i180.0N1—C1—H1125.3
Cd1—OW1—HW1A116.5C8ii—C10—C9120.31 (17)
Cd1—OW1—HW1B129.1C8ii—C10—H10119.8
HW1A—OW1—HW1B110.8C9—C10—H10119.8
C3—N1—C1105.55 (13)N4—C4—N3111.29 (14)
C3—N1—Cd1110.01 (10)N4—C4—C3121.10 (13)
C1—N1—Cd1144.33 (11)N3—C4—C3127.58 (14)
C3—N2—C2107.07 (13)C1—C2—N2106.66 (14)
C3—N2—H2A126.5C1—C2—H2126.7
C2—N2—H2A126.5N2—C2—H2126.7
C4—N3—C5106.95 (14)C5—C6—N4109.06 (15)
C4—N3—H3A126.5C5—C6—H6125.5
C5—N3—H3A126.5N4—C6—H6125.5
C4—N4—C6105.74 (13)C6—C5—N3106.96 (15)
C4—N4—Cd1111.59 (10)C6—C5—H5126.5
C6—N4—Cd1142.64 (11)N3—C5—H5126.5
N4—Cd1—N1—C33.63 (10)C1—N1—C3—C4179.68 (14)
N4i—Cd1—N1—C3176.37 (10)Cd1—N1—C3—C43.15 (18)
OW1—Cd1—N1—C392.23 (11)C2—N2—C3—N10.33 (18)
OW1i—Cd1—N1—C387.77 (11)C2—N2—C3—C4179.77 (16)
N4—Cd1—N1—C1178.95 (19)C3—N1—C1—C20.00 (19)
N4i—Cd1—N1—C11.05 (19)Cd1—N1—C1—C2175.44 (13)
OW1—Cd1—N1—C192.45 (19)C8—C9—C10—C8ii0.4 (3)
OW1i—Cd1—N1—C187.55 (19)C6—N4—C4—N30.15 (19)
N1i—Cd1—N4—C4176.15 (11)Cd1—N4—C4—N3178.11 (11)
N1—Cd1—N4—C43.85 (11)C6—N4—C4—C3177.99 (15)
OW1—Cd1—N4—C495.99 (11)Cd1—N4—C4—C33.75 (19)
OW1i—Cd1—N4—C484.01 (11)C5—N3—C4—N40.0 (2)
N1i—Cd1—N4—C61.1 (2)C5—N3—C4—C3177.98 (17)
N1—Cd1—N4—C6178.9 (2)N1—C3—C4—N40.4 (2)
OW1—Cd1—N4—C686.8 (2)N2—C3—C4—N4179.02 (15)
OW1i—Cd1—N4—C693.2 (2)N1—C3—C4—N3178.18 (15)
C9—C8—C7—O2151.17 (18)N2—C3—C4—N31.2 (3)
C10ii—C8—C7—O228.4 (2)N1—C1—C2—N20.2 (2)
C9—C8—C7—O130.0 (3)C3—N2—C2—C10.31 (18)
C10ii—C8—C7—O1150.43 (18)C4—N4—C6—C50.2 (2)
C10ii—C8—C9—C100.4 (3)Cd1—N4—C6—C5177.10 (16)
C7—C8—C9—C10179.16 (16)N4—C6—C5—N30.2 (2)
C1—N1—C3—N20.21 (18)C4—N3—C5—C60.1 (2)
Cd1—N1—C3—N2177.38 (10)
Symmetry codes: (i) x+2, y, z+2; (ii) x+2, y, z+3.
Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
OW1—HW1A···O1i0.841.882.718 (2)171
OW1—HW1B···O2iii0.891.972.822 (2)161
N2—H2A···O1iv0.861.892.7471 (18)171
N3—H3A···O2iv0.861.862.6972 (19)165
Symmetry codes: (i) x+2, y, z+2; (iii) x+1/2, y+1/2, z1/2; (iv) x+1, y, z.

Experimental details

Crystal data
Chemical formula[Cd(C6H6N4)2(H2O)2](C8H4O4)
Mr580.84
Crystal system, space groupMonoclinic, P21/n
Temperature (K)293
a, b, c (Å)8.336 (2), 11.009 (3), 12.688 (4)
β (°) 93.674 (3)
V3)1161.9 (6)
Z2
Radiation typeMo Kα
µ (mm1)0.99
Crystal size (mm)0.58 × 0.53 × 0.25
Data collection
DiffractometerBruker SMART CCD
Absorption correctionMulti-scan
(SADABS; Sheldrick, 1996) or Bruker (1997)?
Tmin, Tmax0.596, 0.786
No. of measured, independent and
observed [I > 2σ(I)] reflections
9682, 2294, 2139
Rint0.014
(sin θ/λ)max1)0.618
Refinement
R[F2 > 2σ(F2)], wR(F2), S 0.018, 0.049, 1.04
No. of reflections2294
No. of parameters162
No. of restraints4
H-atom treatmentH-atom parameters constrained
Δρmax, Δρmin (e Å3)0.30, 0.26

Computer programs: SMART (Bruker, 1997), SAINT (Bruker, 1997), SAINT, SHELXS97 (Sheldrick, 1997), SHELXL97 (Sheldrick, 1997), SHELXTL (Bruker, 1997), SHELXL97 and local programs.

Selected bond lengths (Å) top
Cd1—N42.2759 (14)Cd1—OW12.4007 (14)
Cd1—N12.3178 (14)
Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
OW1—HW1A···O1i0.841.882.718 (2)171
OW1—HW1B···O2ii0.891.972.822 (2)161
N2—H2A···O1iii0.861.892.7471 (18)171
N3—H3A···O2iii0.861.862.6972 (19)165
Symmetry codes: (i) x+2, y, z+2; (ii) x+1/2, y+1/2, z1/2; (iii) x+1, y, z.
 

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