Crystal structure of catena-poly[[di­aqua­cadmium(II)]-μ-3,3′-(1,3-phenyl­ene)diacrylato]

In the crystal of the title polymeric complex, [Cd(C₁₂H₈O₄)(H₂O)₂]_n, the Cd^II cation, located on a twofold rotation axis, is coordinated by two water mol­ecules and chelated by two phenyl­enediacrylate anions (mpda) in a distorted octa­hedral geometry. The mpda anions bridge the Cd^II cations, forming helical chains propagating along the c-axis direction. The mpba anion has twofold symmetry with two benzene C atoms located on the twofold rotation axis. In the crystal, O—H⋯O hydrogen bonds link the polymeric helical chains into a three-dimensional supra­molecular architecture.

1. Related literature

For V-shaped metal complexes coordinated by the phenyl­enediacrylate anion, see: Liu et al. (2013). For related metal-organic coordination polymers with an m-phenyl­enedi­carboxyl­ate ligand, see: Yang et al. (2014).

2. Experimental

2.1. Crystal data

• [Cd(C₁₂H₈O₄)(H₂O)₂]

• M_r = 364.62

• Orthorhombic, C 222₁

• a = 5.3145 (12) Å

• b = 11.991 (3) Å

• c = 19.767 (5) Å

• V = 1259.7 (5) ų

• Z = 4

• Mo Kα radiation

• μ = 1.75 mm⁻¹

• T = 293 K

• 0.35 × 0.32 × 0.25 mm

2.2. Data collection

• Bruker SMART APEXII CCD diffractometer

• Absorption correction: multi-scan (SADABS; Bruker, 2008) T_min = 0.59, T_max = 0.68

• 3205 measured reflections

• 1107 independent reflections

• 950 reflections with I > 2σ(I)

• R_int = 0.036

2.3. Refinement

• R[F² > 2σ(F²)] = 0.039

• wR(F²) = 0.155

• S = 1.08

• 1107 reflections

• 96 parameters

• 2 restraints

• H atoms treated by a mixture of independent and constrained refinement

• Δρ_max = 0.93 e Å⁻³

• Δρ_min = −0.64 e Å⁻³

• Absolute structure: Flack (1983), 1035 Friedel pairs

• Absolute structure parameter: 0.07 (19)

Table 1
Selected bond lengths (Å)

Cd1—O1	2.329 (6)
Cd1—O2	2.380 (6)
Cd1—O3W	2.199 (7)

Table 2
Hydrogen-bond geometry (Å, °)

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
O3W—H1A⋯O1^i	0.85 (2)	1.88 (4)	2.695 (9)	160 (8)
O3W—H1B⋯O2^ii	0.84 (2)	1.92 (3)	2.736 (8)	162 (8)
Symmetry codes: (i) x-1, -y+2, -z+2; (ii) .

Data collection: APEX2 (Bruker, 2008); cell refinement: SAINT (Bruker, 2008); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: DIAMOND (Brandenburg, 2008)); software used to prepare material for publication: PLATON (Spek, 2009).

Supporting information

S1. Introduction

In crystal engineering, a great inter­est is focused on the supra­molecular self-assembly of helical or chiral coordination polymers from appropriately bridging ligands and metallic tectons through either coordinate bonds and hydrogen bonds. Although much effort has been devoted to the assembly of helical or chiral coordination polymers based on chiral or achiral ligands, the design and construction of chiral coordination polymer based on helical topology is still a great challenge for chemists.

S2. Experimental

All reagents and solvents employed were commercially available and were used as received without further purification.

S2.1. Synthesis and crystallization

A mixture of Cd(NO₃)₂·4H₂O (62 mg, 0.25 mmol), m-phenyl­enediacrylic acid (H₂mpda, 44 mg, 0.2 mmol) and H₂O (10 mL) was sealed in a 25 mL stainless steel reactor with a Teflon liner, heated to 413 K for 3 d and then cooled to room temperature. The crystals were washed with methanol to give the title complex in about 35% yield (based on the H₂mpda ligand).

S2.2. Refinement

All non-hydrogen atoms are easily found from the different Fourier maps and refined anisotropically. All H atoms of H₂O molecules are found in the difference Fourier map. The C-bound H atoms of aromatic rings were refined using a riding model [0.93 Å (CH) and U_iso(H) = 1.2U_eq(C)].

S3. Results and discussion

The m-phenyl­enediacrylate (mpda) has various conformations for the rotation of carbon-carbon bonds, such as the C—C single bonds between aromatic rings and C=C bonds. The V-shaped mpda coordinated with metal ions have been documented (Liu et al., 2013). But the mpda has not been well exploited in constructing metal-organic coordination polymers in comparison with the m-phenyl­enedi­carboxyl­ate ligand (Yang et al., 2014). Herein, we report a poly[(m-phenyl­enediacrylate)(water)cadmium] with the formulae [Cd(mpda)(H₂O)₂]_n (1). The title compound crystallizes in the chiral C222 (1) space group, and contains a homochiral left-handed single-stranded helical chain.

In the structure of 1 (Fig. 1), the Cd²⁺ centre adopts a six-coordinated mode with a distorted o­cta­hedral geometry (CdO₆) via binding to two water O atoms and four O atoms from two different CO₂^- groups of mpda ligands [O1, O2, O1ⁱ, O2ⁱ; symmetry code: (i) x,-y+2,-z+2]. The Cd—O distances range from 2.199 (7) to 2.380 (6) Å. Taking account of the O3W—Cd1—O3Wⁱ angle of 92.1 (4)°, the coordination mode of Cd²⁺ ion may play an determining role in the formation of the Cd1ⁱ···Cd1···Cd1ⁱ angle of 85.65°. Each mpda ligand with a monodentate mode bridges two different Cd²⁺ ions, via carboxyl­ate groups at each end of the ligand molecule. Of the structure of the mpda, two acrylate groups (CH=CH-COO^-) are located at the benzene ring in a trans-position fashion. The dihedral angles of the CH=CH-COO^- and C₆H₄—CH=CH group are ca.11.4° and 7.9°, respectively, while that of C1···C7···C6···C1ⁱ is 180°. These dihedral angle data indicate that the mpda ligand is nearly coplanar and there exist intra­molecular π-π electronic conjugations.

The mpda ligands serve as V-shaped bridges to link the metal ions into infinite helical coordination chains running along the c-axis, with the Cd···Cd distance separated by mpda being 14.54 Å. The helical pitch of 19.767 (5) Å is equal to the c dimension of the unit cell. There has the one and only left-handed single-stranded chain in 1, which reveals that this work presents a new unusual example of homochiral architecture based on the helical topology. In 1, the packing of the helical chains is sustained by complicated hydrogen bonds and π–π stacking involving all the coordinated water molecules, and the C=C double bonds and phenyl­ene rings of the mpda ligands. Each phenyl­ene ring from one chain inter­acts with a C=C double bond from another chain, with the inter­plane distances being 3.53 Å. Careful examination of the structure indicates that strong inter­chain hydrogen bonds of O3W—H1A···O1ⁱⁱⁱ [2.695 (6) Å; Symmetry code: (iii) x-1, -y+2, -z+2] exist between the two independent chains. It is clear that the hydrogen (H1A) atoms of one coordinated water molecule serve as the acceptors, while the oxygen (O1ⁱⁱⁱ) atoms of the mpda ligands serve as the donors in each self-recognition site. The above-mentioned π–π and O3W—H1A···O1ⁱⁱⁱ inter­actions bring the helical coordination chains into wave-shaped two-dimensional layers. Further a three-dimensional supra­molecular architecture is result from wave-shaped motifs through the inter­layer hydrogen bonds of O3W—H1B···O2^iv [2.736 (8) Å; Symmetry code: (iv) x-1/2, -y+3/2, -z+2].

Related literature

For V-shaped metal complexes coordinated by the phenylenediacrylate anion, see: Liu et al. (2013). For related metal-organic coordination polymers with an m-phenylenedicarboxylate ligand, see: Yang et al. (2014).

Structure description

In crystal engineering, a great inter­est is focused on the supra­molecular self-assembly of helical or chiral coordination polymers from appropriately bridging ligands and metallic tectons through either coordinate bonds and hydrogen bonds. Although much effort has been devoted to the assembly of helical or chiral coordination polymers based on chiral or achiral ligands, the design and construction of chiral coordination polymer based on helical topology is still a great challenge for chemists.

All reagents and solvents employed were commercially available and were used as received without further purification.

The m-phenyl­enediacrylate (mpda) has various conformations for the rotation of carbon-carbon bonds, such as the C—C single bonds between aromatic rings and C=C bonds. The V-shaped mpda coordinated with metal ions have been documented (Liu et al., 2013). But the mpda has not been well exploited in constructing metal-organic coordination polymers in comparison with the m-phenyl­enedi­carboxyl­ate ligand (Yang et al., 2014). Herein, we report a poly[(m-phenyl­enediacrylate)(water)cadmium] with the formulae [Cd(mpda)(H₂O)₂]_n (1). The title compound crystallizes in the chiral C222 (1) space group, and contains a homochiral left-handed single-stranded helical chain.

In the structure of 1 (Fig. 1), the Cd²⁺ centre adopts a six-coordinated mode with a distorted o­cta­hedral geometry (CdO₆) via binding to two water O atoms and four O atoms from two different CO₂^- groups of mpda ligands [O1, O2, O1ⁱ, O2ⁱ; symmetry code: (i) x,-y+2,-z+2]. The Cd—O distances range from 2.199 (7) to 2.380 (6) Å. Taking account of the O3W—Cd1—O3Wⁱ angle of 92.1 (4)°, the coordination mode of Cd²⁺ ion may play an determining role in the formation of the Cd1ⁱ···Cd1···Cd1ⁱ angle of 85.65°. Each mpda ligand with a monodentate mode bridges two different Cd²⁺ ions, via carboxyl­ate groups at each end of the ligand molecule. Of the structure of the mpda, two acrylate groups (CH=CH-COO^-) are located at the benzene ring in a trans-position fashion. The dihedral angles of the CH=CH-COO^- and C₆H₄—CH=CH group are ca.11.4° and 7.9°, respectively, while that of C1···C7···C6···C1ⁱ is 180°. These dihedral angle data indicate that the mpda ligand is nearly coplanar and there exist intra­molecular π-π electronic conjugations.

The mpda ligands serve as V-shaped bridges to link the metal ions into infinite helical coordination chains running along the c-axis, with the Cd···Cd distance separated by mpda being 14.54 Å. The helical pitch of 19.767 (5) Å is equal to the c dimension of the unit cell. There has the one and only left-handed single-stranded chain in 1, which reveals that this work presents a new unusual example of homochiral architecture based on the helical topology. In 1, the packing of the helical chains is sustained by complicated hydrogen bonds and π–π stacking involving all the coordinated water molecules, and the C=C double bonds and phenyl­ene rings of the mpda ligands. Each phenyl­ene ring from one chain inter­acts with a C=C double bond from another chain, with the inter­plane distances being 3.53 Å. Careful examination of the structure indicates that strong inter­chain hydrogen bonds of O3W—H1A···O1ⁱⁱⁱ [2.695 (6) Å; Symmetry code: (iii) x-1, -y+2, -z+2] exist between the two independent chains. It is clear that the hydrogen (H1A) atoms of one coordinated water molecule serve as the acceptors, while the oxygen (O1ⁱⁱⁱ) atoms of the mpda ligands serve as the donors in each self-recognition site. The above-mentioned π–π and O3W—H1A···O1ⁱⁱⁱ inter­actions bring the helical coordination chains into wave-shaped two-dimensional layers. Further a three-dimensional supra­molecular architecture is result from wave-shaped motifs through the inter­layer hydrogen bonds of O3W—H1B···O2^iv [2.736 (8) Å; Symmetry code: (iv) x-1/2, -y+3/2, -z+2].

For V-shaped metal complexes coordinated by the phenylenediacrylate anion, see: Liu et al. (2013). For related metal-organic coordination polymers with an m-phenylenedicarboxylate ligand, see: Yang et al. (2014).

Synthesis and crystallization

A mixture of Cd(NO₃)₂·4H₂O (62 mg, 0.25 mmol), m-phenyl­enediacrylic acid (H₂mpda, 44 mg, 0.2 mmol) and H₂O (10 mL) was sealed in a 25 mL stainless steel reactor with a Teflon liner, heated to 413 K for 3 d and then cooled to room temperature. The crystals were washed with methanol to give the title complex in about 35% yield (based on the H₂mpda ligand).

Refinement details

All non-hydrogen atoms are easily found from the different Fourier maps and refined anisotropically. All H atoms of H₂O molecules are found in the difference Fourier map. The C-bound H atoms of aromatic rings were refined using a riding model [0.93 Å (CH) and U_iso(H) = 1.2U_eq(C)].

Computing details

Data collection: APEX2 (Bruker, 2008); cell refinement: SAINT (Bruker, 2008); data reduction: SAINT (Bruker, 2008); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: DIAMOND (Brandenburg, 2008)); software used to prepare material for publication: PLATON (Spek, 2009).

Figures

Fig. 1. Part of the crystal structure of the mpda ligand and Cd^II centres in (1), showing the atom-numbering scheme. Displacement ellipsoids are drawn at the 30% probability level. [Symmetry codes: (i) x, -y + 2, -z + 2; (ii) -x + 2, y, -z + 3/2].

catena-Poly[[diaquacadmium(II)]-µ-3,3'-(1,3-phenylene)diacrylato]

Crystal data

[Cd(C12H8O4)(H2O)2]	F(000) = 720
Mr = 364.62	Dx = 1.922 Mg m^−3
Orthorhombic, C2221	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: C 2c 2	Cell parameters from 1107 reflections
a = 5.3145 (12) Å	θ = 2.0–25.0°
b = 11.991 (3) Å	µ = 1.75 mm^−1
c = 19.767 (5) Å	T = 293 K
V = 1259.7 (5) Å^3	Block, colorless
Z = 4	0.35 × 0.32 × 0.25 mm

Data collection

Bruker SMART APEXII CCD diffractometer	1107 independent reflections
Radiation source: fine-focus sealed tube	950 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.036
ω scans	θmax = 25.0°, θmin = 2.1°
Absorption correction: multi-scan (SADABS; Bruker, 2008)	h = −5→6
Tmin = 0.59, Tmax = 0.68	k = −13→14
3205 measured reflections	l = −19→23

Refinement

Refinement on F^2	Secondary atom site location: difference Fourier map
Least-squares matrix: full	Hydrogen site location: inferred from neighbouring sites
R[F^2 > 2σ(F^2)] = 0.039	H atoms treated by a mixture of independent and constrained refinement
wR(F^2) = 0.155	w = 1/[σ^2(Fo^2) + (0.1P)^2 + 7.5572P] where P = (Fo^2 + 2Fc^2)/3
S = 1.08	(Δ/σ)max < 0.001
1107 reflections	Δρmax = 0.93 e Å^−3
96 parameters	Δρmin = −0.64 e Å^−3
2 restraints	Absolute structure: Flack (1983), 1035 Friedel pairs
Primary atom site location: structure-invariant direct methods	Absolute structure parameter: 0.07 (19)

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
Cd1	−0.00336 (16)	1.0000	1.0000	0.0311 (3)
O1	0.2947 (11)	0.9898 (5)	0.9139 (3)	0.0332 (13)
O2	0.1598 (11)	0.8310 (5)	0.9546 (3)	0.0335 (14)
O3W	−0.2906 (13)	0.8960 (5)	1.0493 (4)	0.0438 (18)
C1	0.307 (2)	0.8841 (8)	0.9156 (4)	0.040 (2)
C2	0.4734 (19)	0.8224 (7)	0.8726 (5)	0.039 (2)
H2	0.4462	0.7460	0.8689	0.046*
C3	0.6643 (18)	0.8655 (8)	0.8375 (4)	0.0329 (19)
H3	0.6894	0.9420	0.8411	0.040*
C4	0.8387 (19)	0.8040 (7)	0.7936 (4)	0.0297 (19)
C5	0.848 (2)	0.6888 (8)	0.7930 (5)	0.041 (2)
H5	0.7472	0.6494	0.8231	0.049*
C6	1.0000	0.6307 (10)	0.7500	0.042 (3)
H6	1.0000	0.5531	0.7500	0.050*
C7	1.0000	0.8616 (10)	0.7500	0.033 (3)
H7	1.0000	0.9392	0.7500	0.039*
H1A	−0.436 (7)	0.917 (7)	1.062 (4)	0.02 (2)*
H1B	−0.288 (15)	0.826 (2)	1.056 (4)	0.01 (2)*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Cd1	0.0265 (5)	0.0292 (5)	0.0377 (5)	0.000	0.000	−0.0032 (3)
O1	0.029 (3)	0.024 (3)	0.046 (3)	−0.001 (3)	0.007 (3)	−0.001 (3)
O2	0.012 (3)	0.027 (3)	0.062 (4)	−0.006 (3)	0.013 (3)	−0.004 (3)
O3W	0.024 (4)	0.028 (3)	0.079 (5)	−0.002 (3)	0.015 (4)	0.001 (4)
C1	0.053 (6)	0.040 (5)	0.027 (4)	−0.009 (5)	0.000 (5)	−0.009 (4)
C2	0.031 (5)	0.026 (4)	0.059 (6)	−0.015 (5)	0.006 (5)	−0.007 (4)
C3	0.024 (4)	0.037 (5)	0.038 (5)	−0.008 (4)	0.005 (4)	−0.001 (4)
C4	0.030 (4)	0.031 (5)	0.028 (4)	−0.004 (5)	0.004 (4)	0.002 (3)
C5	0.046 (6)	0.030 (5)	0.046 (5)	−0.012 (5)	0.008 (5)	0.004 (4)
C6	0.048 (8)	0.024 (6)	0.054 (7)	0.000	0.008 (8)	0.000
C7	0.041 (7)	0.025 (6)	0.032 (6)	0.000	0.006 (7)	0.000

Geometric parameters (Å, º)

Cd1—O1^i	2.329 (6)	C2—C3	1.334 (13)
Cd1—O1	2.329 (6)	C2—H2	0.9300
Cd1—O2^i	2.380 (6)	C3—C4	1.468 (12)
Cd1—O2	2.380 (6)	C3—H3	0.9300
Cd1—O3W	2.199 (7)	C4—C5	1.383 (14)
Cd1—O3W^i	2.199 (7)	C4—C7	1.398 (10)
Cd1—C1^i	2.727 (10)	C5—C6	1.363 (12)
O1—C1	1.270 (12)	C5—H5	0.9300
O2—C1	1.269 (12)	C6—C5^ii	1.363 (12)
O3W—H1A	0.85 (2)	C6—H6	0.9300
O3W—H1B	0.84 (2)	C7—C4^ii	1.398 (10)
C1—C2	1.432 (14)	C7—H7	0.9300
O3W—Cd1—O3W^i	92.1 (4)	Cd1—O3W—H1B	128 (6)
O3W—Cd1—O1^i	100.3 (3)	H1A—O3W—H1B	105 (9)
O3W^i—Cd1—O1^i	140.0 (2)	O2—C1—O1	119.0 (9)
O3W—Cd1—O1	140.0 (2)	O2—C1—C2	118.8 (9)
O3W^i—Cd1—O1	100.3 (3)	O1—C1—C2	122.1 (9)
O1^i—Cd1—O1	94.3 (3)	C3—C2—C1	125.3 (9)
O3W—Cd1—O2^i	124.6 (3)	C3—C2—H2	117.3
O3W^i—Cd1—O2^i	86.4 (2)	C1—C2—H2	117.3
O1^i—Cd1—O2^i	55.3 (2)	C2—C3—C4	126.4 (8)
O1—Cd1—O2^i	94.2 (2)	C2—C3—H3	116.8
O3W—Cd1—O2	86.4 (2)	C4—C3—H3	116.8
O3W^i—Cd1—O2	124.6 (3)	C5—C4—C7	117.8 (9)
O1^i—Cd1—O2	94.2 (2)	C5—C4—C3	122.0 (9)
O1—Cd1—O2	55.3 (2)	C7—C4—C3	120.2 (8)
O2^i—Cd1—O2	137.3 (3)	C6—C5—C4	122.6 (10)
O3W—Cd1—C1^i	116.0 (3)	C6—C5—H5	118.7
O3W^i—Cd1—C1^i	113.7 (3)	C4—C5—H5	118.7
O1^i—Cd1—C1^i	27.7 (3)	C5—C6—C5^ii	118.5 (12)
O1—Cd1—C1^i	93.6 (3)	C5—C6—H6	120.7
O2^i—Cd1—C1^i	27.7 (3)	C5^ii—C6—H6	120.7
O2—Cd1—C1^i	116.4 (3)	C4^ii—C7—C4	120.8 (11)
C1—O1—Cd1	93.9 (6)	C4^ii—C7—H7	119.6
C1—O2—Cd1	91.5 (5)	C4—C7—H7	119.6
Cd1—O3W—H1A	127 (6)

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

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
O3W—H1A···O1^iii	0.85 (2)	1.88 (4)	2.695 (9)	160 (8)
O3W—H1B···O2^iv	0.84 (2)	1.92 (3)	2.736 (8)	162 (8)

Symmetry codes: (iii) x−1, −y+2, −z+2; (iv) x−1/2, −y+3/2, −z+2.