catena-Poly[[bis­(4-carboxy­cyclo­hexane­carboxyl­ato-κ²O¹,O^1′)cadmium(II)]-μ-1,4-bis­(imidazol-1-ylmeth­yl)benzene-κ²N³:N^3′]

In the title coordination polymer, [Cd(C₈H₁₁O₄)₂(C₁₄H₁₄N₄)]_n, the Cd atom (site symmetry 2) is six-coordin­ated by two O,O′-bidentate 4-carboxy­cyclo­hexa­necarboxyl­ate (Hchdc) ligands and two N atoms from two different 1,4-bis­(imidazol-1-ylmeth­yl)benzene (1,4-bix) mol­ecules in a very distorted cis-CdN₂O₄ octa­hedral environment. The 1,4-bix mol­ecules act as bridging ligands that bind two Cd^II atoms, thus forming an infinite chain propagating in [100], which is decorated by the Hchdc anions. The structure is completed by O—H...O hydrogen bonds, which link the chains together.

Key indicators

• Single-crystal X-ray study
• T = 292 K
• Mean [sigma](C-C) = 0.009 Å
• R factor = 0.052
• wR factor = 0.120
• Data-to-parameter ratio = 16.4

checkCIF/PLATON results

No syntax errors found



Alert level B
PLAT242_ALERT_2_B Check Low       Ueq as Compared to Neighbors for        C14

Alert level C
PLAT094_ALERT_2_C Ratio of Maximum / Minimum Residual Density ....       2.06
PLAT220_ALERT_2_C Large Non-Solvent    C     Ueq(max)/Ueq(min) ...       2.60 Ratio
PLAT230_ALERT_2_C Hirshfeld Test Diff for    C3     --  C4      ..       5.90 su
PLAT241_ALERT_2_C Check High      Ueq as Compared to Neighbors for         O1
PLAT241_ALERT_2_C Check High      Ueq as Compared to Neighbors for         O2
PLAT241_ALERT_2_C Check High      Ueq as Compared to Neighbors for         C4
PLAT242_ALERT_2_C Check Low       Ueq as Compared to Neighbors for         C8
PLAT334_ALERT_2_C Small Average Benzene C-C Dist.  C13    -C13_b         1.36 Ang.
PLAT342_ALERT_3_C Low Bond Precision on C-C Bonds (x 1000) Ang ...          9
PLAT234_ALERT_4_C Large Hirshfeld Difference C4     --  C5      ..       0.19 Ang.

   0 ALERT level A = In general: serious problem
   1 ALERT level B = Potentially serious problem
  10 ALERT level C = Check and explain
   0 ALERT level G = General alerts; check

   0 ALERT type 1 CIF construction/syntax error, inconsistent or missing data
   9 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
   1 ALERT type 4 Improvement, methodology, query or suggestion
   0 ALERT type 5 Informative message, check

---

S1. Comment

The rational design and synthesis of metal-organic coordination polymers have received intense interest due to their fascinating structural topologies and potential applications as functional materials (e.g. Fang et al., 2006). These coordination polymers can be specially designed by the careful selection of metal cations with preferred coordination geometries, the nature of the anions, the structure of the connecting ligands, and the reaction conditions (Kim & Jung, 2002). The selection of ligand is extremely important because changing the structures of the ligands can control and adjust the topologies of coordination frameworks. Among these mentioned above, chain structures have received much attention in coordination chemistry and life sciecnce (Lehn, 1990). So far, many chain complexes have been generated by self-assembly processes (Chen & Liu, 2002). In this regard, metal 1,4-benzenedicarboxylates (1,4-bdc) have been widely studied (Qi et al., 2003). However, so far, less attention has been given to the 1,4-cyclohexanedicarboxylic acid ligand (H₂chdc). The H₂chdc as an important analogues of 1,4-bdc may be a good candidate for the construction of metal-organic architectures. On the other hand, 4,4'-byridine is a rigid rod-like spacer, well known in the construction of metal-organic polymers, and it has adopted numerous interesting supramolecular architectures (Batten & Robson, 1998). However, flexible ligands such as 1,4-bis(imidazole-1-ylmethyl)-benzene (1,4-bix) have not been so well explored to date (Yang et al., 2008). In this work, the combination of 1,4-bix with H₂chdc and Cd^II cations resulted in the title compound [Cd(1,4-bix)(Hchdc)₂], (I), a new one-dimensional chain coordination polymer.

The selected bond lengthes and angles are listed in Table 1. In compound (I), the Cd^II atom is is six-coordinated by four carboxylate O atoms from two different Hchdc ligands, and two N atoms from two different 1,4-bix molecules in a distorted octahedral environment (Fig. 1). The O1, O2, O2ⁱ and N1ⁱ atoms comprise the basal plane, whereas the N1 and O1ⁱ occupy the axial positions of the octahedron. As shown in Fig. 2, each 1,4-bix acts as a bridging ligand that binds two Cd^II atoms, thus forming a unique chain. The chain is decorated with Hchdc molecules alternately at two sides. Furthermore, the O—H···O hydrogen bonds link the chains together, stablizing the structure of (I).

Related literature

For related structures, see: Qi et al. (2003). For background to coordination polymers, see: Chen & Liu (2002); Fang et al. (2006); Kim & Jung (2002); Lehn (1990); Batten & Robson (1998); Yang et al. (2008).

S2. Experimental

A mixture of CdCl₂^.2H₂O (0.5 mmol), H₂chdc acid (0.5 mmol), 1,4-bix (0.5 mmol), and H₂O (500 mmol) was adjusted to pH = 5.8 by addition of aqueous NaOH solution, and heated at 453 K for 5 days. After the mixture was slowly cooled to room temperature, colorless blocks of (I) were recovered in a 28% yield.

S3. Refinement

The H atoms were positioned geometrically (C—H = 0.93–0.97 Å, O—H = 0.82Å) and refined as riding, with U_iso(H)=1.2U_eq(carrier).

Computing details

Data collection: CrysAlis CCD (Oxford Diffraction, 2006); cell refinement: CrysAlis CCD (Oxford Diffraction, 2006); data reduction: CrysAlis RED (Oxford Diffraction, 2006); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: SHELXTL-Plus (Sheldrick, 2008); software used to prepare material for publication: SHELXL97 (Sheldrick, 2008).

Figures

	Fig. 1. The structure of (I), showing displacement ellipsoids drawn at the 20% probability level. Symmetry code: (i) 3/2 - x, 1/2 - y, z; (ii) 5/2 - x, -1/2 - y, z.
	Fig. 2. View of the chain structure of (I).

catena-Poly[[bis(4-carboxycyclohexanecarboxylato- κ²O¹,O^1')cadmium(II)]-µ-1,4-bis(imidazol-1- ylmethyl)benzene-κ²N³:N^3']

Crystal data

[Cd(C8H11O4)2(C14H14N4)]	F(000) = 1424
Mr = 693.03	Dx = 1.475 Mg m^−3
Orthorhombic, Pccn	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ab 2ac	Cell parameters from 3190 reflections
a = 12.6317 (5) Å	θ = 3.0–26.5°
b = 19.9697 (12) Å	µ = 0.75 mm^−1
c = 12.3703 (7) Å	T = 292 K
V = 3120.4 (3) Å^3	Block, colorless
Z = 4	0.26 × 0.22 × 0.17 mm

Data collection

Oxford Diffraction Gemini R Ultra diffractometer	3190 independent reflections
Radiation source: fine-focus sealed tube	1658 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.116
Detector resolution: 10.0 pixels mm^-1	θmax = 26.5°, θmin = 4.7°
ω scans	h = −15→15
Absorption correction: multi-scan (CrysAlis RED; Oxford Diffraction, 2006)	k = −24→24
Tmin = 0.816, Tmax = 0.882	l = −15→15
26676 measured reflections

Refinement

Refinement on F^2	Primary atom site location: structure-invariant direct methods
Least-squares matrix: full	Secondary atom site location: difference Fourier map
R[F^2 > 2σ(F^2)] = 0.052	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.120	H-atom parameters constrained
S = 0.95	w = 1/[σ^2(Fo^2) + (0.0575P)^2] where P = (Fo^2 + 2Fc^2)/3
3190 reflections	(Δ/σ)max < 0.001
195 parameters	Δρmax = 0.62 e Å^−3
0 restraints	Δρmin = −0.30 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	0.7200 (5)	0.1255 (3)	0.1946 (5)	0.0556 (16)
C2	0.7134 (5)	0.0551 (3)	0.1562 (5)	0.0703 (18)
H2	0.6472	0.0495	0.1158	0.084*
C3	0.8075 (6)	0.0347 (3)	0.0813 (6)	0.089 (2)
H3A	0.8072	0.0627	0.0172	0.107*
H3B	0.8738	0.0420	0.1190	0.107*
C4	0.7998 (7)	−0.0363 (4)	0.0488 (6)	0.106 (3)
H4A	0.8606	−0.0478	0.0045	0.127*
H4B	0.7367	−0.0427	0.0054	0.127*
C5	0.7956 (5)	−0.0833 (3)	0.1467 (6)	0.082 (2)
H5	0.7788	−0.1281	0.1192	0.099*
C6	0.7065 (7)	−0.0639 (4)	0.2243 (7)	0.098 (2)
H6A	0.6387	−0.0729	0.1905	0.118*
H6B	0.7113	−0.0910	0.2891	0.118*
C7	0.7123 (6)	0.0065 (3)	0.2537 (6)	0.089 (2)
H7A	0.7758	0.0137	0.2961	0.107*
H7B	0.6521	0.0172	0.2992	0.107*
C8	0.9032 (6)	−0.0881 (3)	0.2022 (7)	0.078 (2)
C9	0.9060 (3)	0.2554 (3)	0.4765 (4)	0.0524 (13)
H9	0.8851	0.2997	0.4856	0.063*
C10	0.9221 (4)	0.1567 (3)	0.4138 (5)	0.0657 (16)
H10	0.9152	0.1192	0.3699	0.079*
C11	0.9818 (5)	0.1601 (3)	0.5038 (5)	0.0665 (18)
H11	1.0218	0.1258	0.5339	0.080*
C12	1.0206 (3)	0.2510 (3)	0.6389 (4)	0.0612 (14)
H12A	0.9962	0.2257	0.7010	0.073*
H12B	0.9972	0.2969	0.6481	0.073*
C13	1.1951 (4)	0.2506 (5)	0.5441 (5)	0.125 (4)
H13	1.1592	0.2521	0.4785	0.150*
C14	1.1390 (3)	0.2497 (3)	0.6368 (4)	0.0479 (11)
C15	1.1954 (4)	0.2499 (4)	0.7277 (5)	0.0693 (15)
H15	1.1599	0.2498	0.7936	0.083*
N1	0.8735 (3)	0.2166 (2)	0.3967 (4)	0.0527 (11)
N2	0.9721 (3)	0.2237 (2)	0.5420 (4)	0.0515 (12)
O1	0.7903 (3)	0.1640 (2)	0.1601 (3)	0.0683 (11)
O2	0.6563 (3)	0.1466 (2)	0.2657 (4)	0.0700 (12)
O3	0.9194 (5)	−0.0730 (3)	0.2950 (5)	0.120 (2)
O4	0.9764 (4)	−0.1119 (2)	0.1406 (4)	0.0951 (15)
H4	1.0323	−0.1134	0.1741	0.143*
Cd1	0.7500	0.2500	0.27740 (4)	0.04487 (19)

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
C1	0.062 (4)	0.045 (3)	0.059 (4)	0.007 (3)	−0.007 (3)	0.005 (3)
C2	0.096 (5)	0.045 (3)	0.069 (4)	0.000 (3)	0.000 (4)	0.002 (3)
C3	0.149 (6)	0.058 (4)	0.061 (4)	−0.006 (4)	0.036 (5)	0.000 (4)
C4	0.118 (6)	0.103 (6)	0.096 (6)	0.048 (5)	−0.013 (5)	−0.008 (5)
C5	0.085 (4)	0.068 (4)	0.093 (6)	0.022 (4)	−0.020 (4)	0.014 (4)
C6	0.095 (5)	0.078 (5)	0.123 (7)	0.020 (4)	0.014 (5)	0.016 (5)
C7	0.111 (6)	0.065 (4)	0.092 (6)	−0.013 (4)	0.027 (4)	0.005 (4)
C8	0.089 (5)	0.058 (4)	0.087 (6)	0.029 (4)	−0.001 (4)	0.002 (4)
C9	0.036 (2)	0.060 (3)	0.062 (3)	0.015 (3)	−0.002 (3)	0.001 (4)
C10	0.067 (4)	0.055 (4)	0.075 (5)	0.009 (3)	−0.018 (3)	0.002 (3)
C11	0.060 (4)	0.062 (4)	0.077 (5)	0.014 (3)	−0.018 (3)	0.006 (3)
C12	0.037 (2)	0.094 (4)	0.052 (3)	0.009 (4)	−0.006 (2)	0.000 (4)
C13	0.042 (3)	0.291 (12)	0.042 (4)	−0.020 (7)	−0.008 (3)	−0.003 (6)
C14	0.040 (2)	0.062 (3)	0.042 (3)	−0.002 (3)	0.001 (2)	−0.009 (4)
C15	0.048 (3)	0.119 (5)	0.041 (3)	−0.006 (5)	0.004 (2)	−0.004 (5)
N1	0.039 (2)	0.056 (3)	0.064 (3)	0.000 (2)	−0.007 (2)	0.006 (3)
N2	0.030 (2)	0.069 (3)	0.056 (3)	−0.0009 (19)	−0.002 (2)	0.006 (2)
O1	0.083 (3)	0.058 (2)	0.064 (3)	0.001 (2)	0.021 (2)	−0.004 (2)
O2	0.051 (2)	0.059 (2)	0.100 (3)	−0.0010 (18)	0.015 (2)	−0.025 (2)
O3	0.143 (5)	0.130 (5)	0.088 (4)	0.059 (4)	−0.019 (4)	−0.005 (4)
O4	0.077 (3)	0.099 (4)	0.110 (4)	0.027 (3)	−0.007 (3)	−0.027 (3)
Cd1	0.0318 (2)	0.0523 (3)	0.0505 (3)	0.0036 (3)	0.000	0.000

Geometric parameters (Å, º)

C1—O1	1.250 (6)	C9—N2	1.325 (7)
C1—O2	1.265 (6)	C9—H9	0.9300
C1—C2	1.487 (8)	C10—C11	1.347 (8)
C1—Cd1	2.716 (6)	C10—N1	1.361 (6)
C2—C7	1.548 (8)	C10—H10	0.9300
C2—C3	1.561 (8)	C11—N2	1.360 (7)
C2—H2	0.9800	C11—H11	0.9300
C3—C4	1.478 (9)	C12—N2	1.453 (7)
C3—H3A	0.9700	C12—C14	1.496 (6)
C3—H3B	0.9700	C12—H12A	0.9700
C4—C5	1.533 (10)	C12—H12B	0.9700
C4—H4A	0.9700	C13—C14	1.347 (7)
C4—H4B	0.9700	C13—C13^i	1.388 (11)
C5—C8	1.526 (9)	C13—H13	0.9300
C5—C6	1.529 (9)	C14—C15	1.331 (7)
C5—H5	0.9800	C15—C15^i	1.379 (10)
C6—C7	1.453 (9)	C15—H15	0.9300
C6—H6A	0.9700	O4—H4	0.8200
C6—H6B	0.9700	Cd1—N1	2.249 (4)
C7—H7A	0.9700	Cd1—O1	2.306 (4)
C7—H7B	0.9700	Cd1—O2	2.384 (4)
C8—O3	1.205 (8)	Cd1—N1^ii	2.249 (4)
C8—O4	1.288 (8)	Cd1—O1^ii	2.306 (4)
C9—N1	1.320 (7)	Cd1—O2^ii	2.384 (4)
O1—C1—O2	119.0 (5)	C11—C10—N1	109.7 (5)
O1—C1—C2	120.8 (5)	C11—C10—H10	125.2
O2—C1—C2	120.2 (6)	N1—C10—H10	125.2
C1—C2—C7	110.2 (5)	C10—C11—N2	106.5 (5)
C1—C2—C3	113.2 (5)	C10—C11—H11	126.8
C7—C2—C3	107.8 (5)	N2—C11—H11	126.8
C1—C2—H2	108.5	N2—C12—C14	113.6 (4)
C7—C2—H2	108.5	N2—C12—H12A	108.8
C3—C2—H2	108.5	C14—C12—H12A	108.8
C4—C3—C2	111.2 (6)	N2—C12—H12B	108.8
C4—C3—H3A	109.4	C14—C12—H12B	108.8
C2—C3—H3A	109.4	H12A—C12—H12B	107.7
C4—C3—H3B	109.4	C14—C13—C13^i	121.7 (3)
C2—C3—H3B	109.4	C14—C13—H13	119.2
H3A—C3—H3B	108.0	C13^i—C13—H13	119.2
C3—C4—C5	112.0 (6)	C15—C14—C13	115.9 (4)
C3—C4—H4A	109.2	C15—C14—C12	121.3 (4)
C5—C4—H4A	109.2	C13—C14—C12	122.7 (5)
C3—C4—H4B	109.2	C14—C15—C15^i	122.4 (3)
C5—C4—H4B	109.2	C14—C15—H15	118.8
H4A—C4—H4B	107.9	C15^i—C15—H15	118.8
C8—C5—C6	112.9 (6)	C9—N1—C10	105.1 (5)
C8—C5—C4	111.2 (6)	C9—N1—Cd1	122.2 (4)
C6—C5—C4	111.5 (6)	C10—N1—Cd1	132.5 (4)
C8—C5—H5	106.9	C9—N2—C11	106.9 (5)
C6—C5—H5	106.9	C9—N2—C12	126.2 (5)
C4—C5—H5	106.9	C11—N2—C12	126.8 (5)
C7—C6—C5	111.5 (6)	C1—O1—Cd1	94.9 (3)
C7—C6—H6A	109.3	C1—O2—Cd1	90.9 (3)
C5—C6—H6A	109.3	C8—O4—H4	109.5
C7—C6—H6B	109.3	N1—Cd1—N1^ii	97.9 (2)
C5—C6—H6B	109.3	N1—Cd1—O1	92.24 (16)
H6A—C6—H6B	108.0	N1^ii—Cd1—O1	141.92 (15)
C6—C7—C2	114.3 (6)	N1—Cd1—O1^ii	141.92 (15)
C6—C7—H7A	108.7	N1^ii—Cd1—O1^ii	92.24 (16)
C2—C7—H7A	108.7	O1—Cd1—O1^ii	102.0 (2)
C6—C7—H7B	108.7	N1—Cd1—O2	97.33 (15)
C2—C7—H7B	108.7	N1^ii—Cd1—O2	87.24 (15)
H7A—C7—H7B	107.6	O1—Cd1—O2	55.00 (14)
O3—C8—O4	122.2 (7)	O1^ii—Cd1—O2	119.83 (15)
O3—C8—C5	124.4 (7)	N1—Cd1—O2^ii	87.24 (15)
O4—C8—C5	113.3 (7)	N1^ii—Cd1—O2^ii	97.33 (15)
N1—C9—N2	111.8 (6)	O1—Cd1—O2^ii	119.83 (15)
N1—C9—H9	124.1	O1^ii—Cd1—O2^ii	55.00 (14)
N2—C9—H9	124.1	O2—Cd1—O2^ii	173.1 (2)

Symmetry codes: (i) −x+5/2, −y+1/2, z; (ii) −x+3/2, −y+1/2, z.

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
O4—H4···O2^iii	0.82	1.86	2.644 (6)	161

Symmetry code: (iii) x+1/2, −y, −z+1/2.