catena-Poly[[diaqua­cadmium(II)]-μ-3,3′-(p-phenyl­ene)diacrylato]

In the title compound, [Cd(C₁₂H₁₀O₄)(H₂O)₂], each Cd^II atom lies on a crystallographic twofold rotation axis and is six-coordinated by four carboxyl­ate O atoms from two different 3,3′-(p-phenyl­ene)diacrylate ligands, and two cis water mol­ecules in a very distorted octa­hedral CdO₆ environment. Each 3,3′-(p-phenyl­ene)diacrylate dianion is centrosymmetric and acts as a bis-chelating ligand that binds two Cd^II atoms, thus forming a zigzag chain. The chain is decorated with water mol­ecules and O—H...O hydrogen bonds link the chains together, forming a three-dimensional supra­molecular structure.

Key indicators

• Single-crystal X-ray study
• T = 293 K
• Mean [sigma](C-C) = 0.003 Å
• R factor = 0.020
• wR factor = 0.046
• Data-to-parameter ratio = 13.0

checkCIF/PLATON results

No syntax errors found



Alert level C
PLAT720_ALERT_4_C Number of Unusual/Non-Standard Label(s) ........          2

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)       2.08

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

   2 ALERT type 1 CIF construction/syntax error, inconsistent or missing data
   0 ALERT type 2 Indicator that the structure model may be wrong or deficient
   0 ALERT type 3 Indicator that the structure quality may be low
   1 ALERT type 4 Improvement, methodology, query or suggestion
   1 ALERT type 5 Informative message, check

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S1. Comment

The supramolecular networks formed by 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 participation of p-phenylenediacrylic acid (H₂pda) in such networks. The pda dianion, as an important analogue of 1,4-bdc may be a good candidate for the construction of metal–organic helical architectures. We selected pda as a bridging ligand and Cd^II as a central metal, generating a new zigzag chain coordination polymer, [Cd(pda)(H₂O)₂], (I), which is reported here.

In compound (I), the Cd^II atom is six-coordinated by four carboxylate atoms from two different pda ligands, and two water molecules in a very distorted octahedral environment (Fig. 1). The O1, O2, O2ⁱ and O1Wⁱ atoms comprise the basal plane, whereas O1W and O1ⁱ occupy the axial positions of the octahedron. The Cd—O(carboxylate) distances range from 2.3251 (16) to 2.3846 (16) Å (Table 1).

As shown in Fig. 2, each pda acts as a bis-chelating ligand that binds two Cd^II atoms, forming a zigzag chain. The chain is decorated with water molecules which participate in O—H···O hydrogen bonds (Table 2) to link the chains together, thus forming a three-dimensional supramolecular structure (Fig. 3).

Related literature

For a related structure, see: Fang et al. (2006). For background, see: Qi et al. (2003).

S2. Experimental

A mixture of CdCl₂.2H₂O (0.5 mmol), H₂pda (0.5 mmol), and H₂O (500 mmol) was adjusted to pH = 7 by addition of aqueous NaOH solution, and heated at 453 K for 6 days. After the mixture was slowly cooled to room temperature, colorless blocks of (I) resulted (38% yield).

S3. Refinement

All the C-bound H atoms were positioned geometrically (C—H = 0.93 Å) and refined as riding, with U_iso(H) = 1.2U_eq(C). The water H-atoms were located in a difference Fourier map, and were refined freely.

Computing details

Data collection: SMART (Bruker, 1998); cell refinement: SAINT (Bruker, 1998); data reduction: SAINT (Bruker, 1998); program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: SHELXTL (Bruker, 1998); software used to prepare material for publication: SHELXTL (Bruker, 1998).

Figures

	Fig. 1. The structure of (I), with displacement ellipsoids drawn at the 30% probability level. (H atoms have been omitted). Symmetry codes: (i) 2 - x, y, 1.5 - z; (ii) 2.5 - x, 0.5 - y, 2 - z.
	Fig. 2. View of the chain structure of (I).
	Fig. 3. View of the three-dimensional supramolecular structure of (I).

catena-Poly[[diaquacadmium(II)]-µ-3,3'-(p-phenylene)diacrylato]

Crystal data

[Cd(C12H10O4)(H2O)2]	F(000) = 720
Mr = 364.62	Dx = 1.921 Mg m^−3
Monoclinic, C2/c	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -C 2yc	Cell parameters from 1235 reflections
a = 11.857 (3) Å	θ = 2.0–26.1°
b = 5.3296 (14) Å	µ = 1.75 mm^−1
c = 20.030 (5) Å	T = 293 K
β = 94.983 (4)°	Block, colourless
V = 1261.0 (6) Å^3	0.31 × 0.21 × 0.19 mm
Z = 4

Data collection

Bruker APEX CCD diffractometer	1235 independent reflections
Radiation source: fine-focus sealed tube	1199 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.016
ω scans	θmax = 26.1°, θmin = 2.0°
Absorption correction: multi-scan (SADABS; Bruker, 1998)	h = −14→11
Tmin = 0.574, Tmax = 0.716	k = −6→5
3315 measured reflections	l = −24→21

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)] = 0.020	Hydrogen site location: difmap (O-H) and geom (C-H)
wR(F^2) = 0.046	H atoms treated by a mixture of independent and constrained refinement
S = 1.11	w = 1/[σ^2(Fo^2) + (0.0216P)^2 + 1.4532P] where P = (Fo^2 + 2Fc^2)/3
1235 reflections	(Δ/σ)max < 0.001
95 parameters	Δρmax = 0.31 e Å^−3
0 restraints	Δρmin = −0.35 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	1.12499 (19)	−0.4749 (4)	0.83239 (11)	0.0287 (5)
C2	1.1910 (2)	−0.2843 (4)	0.87299 (13)	0.0362 (6)
H2	1.2691	−0.2784	0.8712	0.043*
C3	1.1430 (2)	−0.1220 (5)	0.91177 (11)	0.0320 (5)
H3	1.0646	−0.1300	0.9113	0.038*
C4	1.1997 (2)	0.0689 (4)	0.95542 (11)	0.0302 (5)
C5	1.1344 (2)	0.2195 (5)	0.99437 (13)	0.0359 (6)
H5	1.0562	0.2002	0.9906	0.043*
C6	1.1833 (2)	0.3962 (5)	1.03827 (12)	0.0356 (5)
H6	1.1379	0.4927	1.0638	0.043*
O1	1.01914 (13)	−0.4967 (3)	0.83570 (8)	0.0305 (4)
O2	1.17575 (13)	−0.6158 (3)	0.79418 (8)	0.0360 (4)
O1W	0.90126 (17)	−1.0774 (4)	0.79925 (11)	0.0429 (5)
Cd1	1.0000	−0.79192 (4)	0.7500	0.02670 (9)
HW11	0.832 (3)	−1.093 (6)	0.7946 (15)	0.057 (9)*
HW12	0.928 (3)	−1.205 (5)	0.8085 (15)	0.035 (8)*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
C1	0.0313 (12)	0.0234 (11)	0.0303 (11)	−0.0003 (9)	−0.0036 (9)	−0.0007 (9)
C2	0.0289 (13)	0.0363 (13)	0.0426 (14)	−0.0034 (10)	−0.0014 (11)	−0.0108 (11)
C3	0.0330 (12)	0.0327 (12)	0.0299 (12)	−0.0052 (10)	0.0008 (9)	−0.0040 (10)
C4	0.0365 (13)	0.0274 (12)	0.0263 (11)	−0.0041 (10)	0.0010 (9)	−0.0029 (9)
C5	0.0310 (12)	0.0379 (14)	0.0391 (13)	−0.0065 (10)	0.0043 (10)	−0.0091 (10)
C6	0.0360 (13)	0.0378 (13)	0.0333 (12)	−0.0020 (11)	0.0055 (10)	−0.0115 (10)
O1	0.0277 (8)	0.0273 (8)	0.0361 (9)	−0.0020 (7)	−0.0002 (7)	−0.0048 (6)
O2	0.0280 (8)	0.0336 (9)	0.0458 (10)	−0.0003 (7)	−0.0008 (7)	−0.0144 (8)
O1W	0.0250 (10)	0.0301 (11)	0.0739 (13)	0.0023 (8)	0.0060 (9)	0.0139 (9)
Cd1	0.02628 (14)	0.02161 (13)	0.03127 (14)	0.000	−0.00282 (9)	0.000

Geometric parameters (Å, º)

Cd1—O1	2.3251 (16)	C3—C4	1.466 (3)
Cd1—O2	2.3846 (16)	C3—H3	0.9300
Cd1—O1W	2.2044 (18)	C4—C6^ii	1.394 (3)
Cd1—O1W^i	2.2044 (18)	C4—C5	1.399 (3)
Cd1—O1^i	2.3251 (16)	C5—C6	1.381 (3)
Cd1—O2^i	2.3846 (16)	C5—H5	0.9300
C1—O2	1.262 (3)	C6—C4^ii	1.394 (3)
C1—O1	1.268 (3)	C6—H6	0.9300
C1—C2	1.482 (3)	O1W—HW11	0.83 (4)
C2—C3	1.324 (3)	O1W—HW12	0.77 (3)
C2—H2	0.9300
O1W^i—Cd1—O1W	92.72 (11)	C3—C2—C1	122.4 (2)
O1W^i—Cd1—O1	140.88 (7)	C3—C2—H2	118.8
O1W—Cd1—O1	99.10 (7)	C1—C2—H2	118.8
O1W^i—Cd1—O1^i	99.10 (7)	C2—C3—C4	127.2 (2)
O1W—Cd1—O1^i	140.88 (7)	C2—C3—H3	116.4
O1—Cd1—O1^i	94.82 (8)	C4—C3—H3	116.4
O1W^i—Cd1—O2	87.52 (7)	C6^ii—C4—C5	117.9 (2)
O1W—Cd1—O2	125.91 (7)	C6^ii—C4—C3	123.2 (2)
O1—Cd1—O2	55.50 (5)	C5—C4—C3	118.9 (2)
O1^i—Cd1—O2	91.93 (6)	C6—C5—C4	121.6 (2)
O1W^i—Cd1—O2^i	125.91 (7)	C6—C5—H5	119.2
O1W—Cd1—O2^i	87.52 (7)	C4—C5—H5	119.2
O1—Cd1—O2^i	91.93 (6)	C5—C6—C4^ii	120.5 (2)
O1^i—Cd1—O2^i	55.50 (5)	C5—C6—H6	119.7
O2—Cd1—O2^i	133.64 (9)	C4^ii—C6—H6	119.7
O2—C1—O1	120.3 (2)	C1—O1—Cd1	93.27 (13)
O2—C1—C2	118.9 (2)	C1—O2—Cd1	90.68 (13)
O1—C1—C2	120.8 (2)	Cd1—O1W—HW11	126 (2)
O2—C1—Cd1	61.59 (11)	Cd1—O1W—HW12	120 (2)
O1—C1—Cd1	58.90 (11)	HW11—O1W—HW12	109 (3)
C2—C1—Cd1	174.99 (17)

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

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
O1W—HW12···O1^iii	0.77 (3)	1.95 (3)	2.703 (3)	170 (3)
O1W—HW11···O2^iv	0.83 (4)	1.85 (4)	2.675 (3)	174 (3)

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