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The title compound, poly­[[aqua­zinc(II)]-μ-benzene-1,3-di­carboxyl­ato-O1:O1′:O2], [Zn(C8H4O4)(H2O)]n, forms a metal–organic coordination network that consists of tetrahedral Zn atoms bonded to one water mol­ecule and three carboxyl­ate groups. Isophthalate groups bridge the four-coordinate Zn centers to generate two-dimensional architectures in the ac plane. These planar zinc isophthalate motifs are linked by infinite C=O...H—O—H interactions along the a axis to form a chiral framework. The observed polar structural pattern originates due to the distorted tetrahedral Zn centers [O—Zn—O 100.7 (2)–136.0 (1)°] and the alignment of the water mol­ecules. Bridging isophthalate groups align to form approximate centrosymmetric motifs.

Supporting information

cif

Crystallographic Information File (CIF) https://doi.org/10.1107/S0108270101004772/bk1593sup1.cif
Contains datablocks global, I

hkl

Structure factor file (CIF format) https://doi.org/10.1107/S0108270101004772/bk1593Isup2.hkl
Contains datablock I

CCDC reference: 166971

Comment top

A considerable number of reports based on metal-organic coordination polymers have appeared over the past few decades. Constructed of catenary ligands bonded to metal centers, these materials have successfully been used to generate desired crystalline architectures with bulk functions (Biradha et al., 1999; Evans & Lin, 2000; Mori & Takamizawa, 2000). The use of metal centers with relatively robust coordination environments and conformationally rigid ligands often produces frameworks with structural preferences. ZnII carboxylates are one such example that form predictable metal center geometries which can be linked through multidentate bridging ligands (Li et al., 1998; Lin et al., 1999; Robl, 1987a). The development of new materials based on metal-organic frameworks requires an understanding of structural biases resulting from the self-assembly of the fundamental components. While many of the principles responsible for the construction of coordination polymers have been exposed (Aakeröy et al., 2000; Guilera & Steed, 1999; Saalfrank et al., 1999), a unified set of criteria that describes specific crystal-packing arrangements remains undiscovered. Since steps towards clarifying structural principles often follow a rational study of the extant crystallographic data, the addition of new structures to this database serve to support or challenge existing structural principles. Here, we describe the synthetic and structural chemistry of the title compound, (I), a coordination polymer comprised of an isophthalic acid complex of ZnII. \sch

The asymmetric unit of (I) contains a Zn atom, one isophthalato group, and one coordinated H2O molecule. Fig. 1 shows the local coordination environment around the Zn center as a distorted tetrahedron (Table 1) comprised of one water molecule and three bridging isophthalato carboxylate O atoms. This geometric pattern is consistent with other ZnII coordination frameworks reported in the literature (Mehrota & Bohra, 1983; Robl, 1987b). Each Zn atom coordinates to six adjacent Zn centers [shortest distance is Zn—Znvi = 4.3323 (3) Å; symmetry code: (vi) 1/2 + x, 1 - y, z] through bridging isophthalato atoms O1, O2, and O3 to give a planar polymeric network in the ac plane (Fig. 2). The two-dimensional architecture is constructed of Zn atoms linked by bidentate carboxylate groups, O1 and O2, along the a axis. This motif is extended along the c axis by unidentate chelation of the remaining carboxylate group to adjacent Zn centers via O3—Zn interactions.

A noteworthy feature is that the noncoordinated carboxylate atom O4 forms infinite chains of undulating O5—H···O4 hydrogen bonds with neighboring chelated water molecules (Fig. 2 and Table 2). This pattern extends along the a axis and links the two-dimensional isophthalato-ZnII coordination networks. The resulting three-dimensional assemblage, constructed from polymeric Zn centers and catemeric hydrogen bonds, lacks residual solvent-accessible regions as determined from examination of the structure with PLATON (Spek, 1990).

The chiral framework of the structure originates from the distorted tetrahedral Zn centers and polar alignment of chelated H2O molecules. Inspection of Table 1 reveals Zn—O bonds that differ by only 0.030 (3) Å, with significant variations in the O—Zn—O angles [100.7 (2)–136.0 (1)°]. The skewed coordination environment of each Zn atom generates a stereogenic metal center with vector properties that are not cancelled by the orientation of neighboring symmetry-related Zn centers. In contrast with these polar structural components, the assemblage of bridging isophthalato groups forms motifs that closely resemble centrosymmetric alignment.

Related literature top

For related literature, see: Aakeröy et al. (2000); Biradha et al. (1999); Evans & Lin (2000); Flack (1983); Guilera & Steed (1999); Li et al. (1998); Lin et al. (1999); Mori & Takamizawa (2000); Robl (1987a, 1987b); Saalfrank et al. (1999); Sheldrick (1997); Spek (1990).

Experimental top

Compound (I) was prepared using a modification of the gel-assisted slow diffusion technique described by Robl (1987b) for the preparation of metal carboxylates. HNO3 (2M) was added dropwise to a solution of Na2H2SiO4 (10 ml, 2 M) and disodium isophthalate (10 ml, 0.01 M). At the appropriate pH, typically 5.0–5.5, the viscosity of the mixture rapidly increased. The silicate mixture was promptly distributed into test tubes and allowed to stiffen to form translucent gels. Each gel was layered with Zn(NO3)2 (2 ml, 0.5 M) and allowed to stand. After 5–6 weeks, transparent colorless plates of (I) grew, with crystal dimensions of up to 2 mm. A crystal suitable for X-ray analysis was fixed to the tip of a glass fiber with cyanoacrylate adhesive.

Refinement top

OH hydrogen positions were located on a difference density map, and the remaining aryl H-atom positions were calculated using a C—H distance of 0.93 Å. Water H atoms were refined isotropically and the remaining H atoms were refined using a riding model with fixed displacement parameters [Uij = 1.2Uij(eq) for the atom to which they were bonded]. The absolute configuration was determined by refinement of the TWIN and BASF commands in SHELXL97 (Sheldrick, 1997) to give an estimated Flack (1983) parameter.

Computing details top

Data collection: XSCANS (Bruker, 1999); cell refinement: XSCANS; data reduction: XSCANS; program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: SHELXTL/PC (Sheldrick, 1994); software used to prepare material for publication: X-SEED (Barbour, 1999).

Figures top
[Figure 1] Fig. 1. The ZnII coordination environment in (I) and the atom-labeling scheme. Displacement ellipsoids are shown at the 60% probability level and H atoms are drawn as small spheres of arbitrary radii [symmetry codes: (i) 3/2 - x, y, 1/2 + z; (ii) 1 - x, 1 - y, 1/2 + z].
[Figure 2] Fig. 2. The projection of the structure of (I) down the b axis, showing the layered coordination polymer linked by infinite arrays of O5—H.·O4 hydrogen-bond interactions.
poly[[aquazinc(II)]-µ-benzene-1,3-dicarboxylato] top
Crystal data top
[Zn(C8H4O4)(H2O)]Dx = 1.907 Mg m3
Mr = 247.50Mo Kα radiation, λ = 0.71073 Å
Orthorhombic, Pca21Cell parameters from 37 reflections
a = 8.3887 (6) Åθ = 20.8–25.0°
b = 6.0883 (5) ŵ = 2.84 mm1
c = 16.8795 (10) ÅT = 298 K
V = 862.09 (11) Å3Plate, colorless
Z = 40.68 × 0.42 × 0.19 mm
F(000) = 496
Data collection top
Siemens P4
diffractometer
1288 reflections with I > 2σ(I)
Radiation source: fine-focus sealed tubeRint = 0.016
Graphite monochromatorθmax = 30.0°, θmin = 2.4°
θ/2θ scansh = 111
Absorption correction: integration
(SHELXTL; Bruker, 1998)
k = 18
Tmin = 0.33, Tmax = 0.59l = 231
1797 measured reflections3 standard reflections every 97 reflections
1377 independent reflections intensity decay: <2.5%
Refinement top
Refinement on F2Secondary atom site location: difference Fourier map
Least-squares matrix: fullHydrogen site location: inferred from neighbouring sites
R[F2 > 2σ(F2)] = 0.034H atoms treated by a mixture of independent and constrained refinement
wR(F2) = 0.085 w = 1/[σ2(Fo2) + (0.0551P)2]
where P = (Fo2 + 2Fc2)/3
S = 1.18(Δ/σ)max = 0.07
1377 reflectionsΔρmax = 0.44 e Å3
135 parametersΔρmin = 1.07 e Å3
1 restraintAbsolute structure: Flack (1983)
Primary atom site location: structure-invariant direct methodsAbsolute structure parameter: 0.02 (2)
Crystal data top
[Zn(C8H4O4)(H2O)]V = 862.09 (11) Å3
Mr = 247.50Z = 4
Orthorhombic, Pca21Mo Kα radiation
a = 8.3887 (6) ŵ = 2.84 mm1
b = 6.0883 (5) ÅT = 298 K
c = 16.8795 (10) Å0.68 × 0.42 × 0.19 mm
Data collection top
Siemens P4
diffractometer
1288 reflections with I > 2σ(I)
Absorption correction: integration
(SHELXTL; Bruker, 1998)
Rint = 0.016
Tmin = 0.33, Tmax = 0.593 standard reflections every 97 reflections
1797 measured reflections intensity decay: <2.5%
1377 independent reflections
Refinement top
R[F2 > 2σ(F2)] = 0.034H atoms treated by a mixture of independent and constrained refinement
wR(F2) = 0.085Δρmax = 0.44 e Å3
S = 1.18Δρmin = 1.07 e Å3
1377 reflectionsAbsolute structure: Flack (1983)
135 parametersAbsolute structure parameter: 0.02 (2)
1 restraint
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
Zn0.64004 (4)0.41094 (6)0.31489 (4)0.02211 (12)
O10.7852 (4)0.5435 (5)0.08640 (17)0.0297 (6)
O20.5858 (3)0.6531 (5)0.16047 (16)0.0289 (5)
O30.6372 (4)0.4945 (6)0.20320 (19)0.0347 (7)
O40.5517 (3)0.7991 (5)0.25925 (17)0.0292 (5)
O50.7496 (3)0.1227 (4)0.3088 (3)0.0315 (6)
C10.6557 (4)0.6439 (6)0.0942 (2)0.0225 (6)
C20.5907 (4)0.7590 (6)0.02366 (19)0.0214 (6)
C30.6135 (4)0.6697 (6)0.0511 (2)0.0218 (6)
H30.66200.53330.05670.026*
C40.5632 (4)0.7854 (6)0.1179 (2)0.0226 (6)
C50.4972 (5)0.9944 (7)0.1101 (2)0.0288 (7)
H50.46791.07400.15480.035*
C60.4755 (6)1.0835 (6)0.0347 (3)0.0321 (9)
H60.43111.22250.02900.039*
C70.5201 (5)0.9644 (7)0.0319 (2)0.0277 (7)
H70.50281.02220.08210.033*
C80.5844 (4)0.6885 (6)0.1986 (2)0.0245 (7)
HAO50.692 (8)0.014 (9)0.290 (3)0.042 (14)*
HBO50.839 (10)0.107 (11)0.276 (6)0.07 (3)*
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
Zn0.02421 (18)0.02674 (18)0.01536 (17)0.00126 (12)0.0005 (2)0.0010 (2)
O10.0317 (15)0.0376 (14)0.0199 (12)0.0112 (11)0.0008 (11)0.0068 (12)
O20.0247 (11)0.0469 (14)0.0151 (10)0.0083 (12)0.0004 (10)0.0003 (12)
O30.0504 (18)0.0351 (17)0.0185 (14)0.0067 (14)0.0039 (11)0.0028 (13)
O40.0306 (12)0.0400 (14)0.0169 (10)0.0033 (11)0.0052 (10)0.0063 (12)
O50.0284 (11)0.0297 (11)0.0364 (16)0.0024 (9)0.0028 (16)0.0015 (17)
C10.0229 (15)0.0265 (14)0.0179 (15)0.0036 (12)0.0005 (13)0.0021 (15)
C20.0210 (14)0.0276 (16)0.0155 (14)0.0005 (13)0.0011 (11)0.0013 (13)
C30.0235 (14)0.0243 (16)0.0174 (15)0.0001 (12)0.0024 (12)0.0006 (14)
C40.0246 (16)0.0251 (16)0.0182 (14)0.0011 (13)0.0013 (12)0.0016 (13)
C50.0337 (18)0.0271 (18)0.0256 (18)0.0059 (16)0.0050 (15)0.0038 (17)
C60.038 (2)0.028 (2)0.031 (2)0.0109 (15)0.0036 (18)0.0016 (16)
C70.0290 (17)0.0329 (17)0.0211 (17)0.0059 (15)0.0000 (14)0.0026 (16)
C80.0233 (14)0.0336 (17)0.0165 (14)0.0016 (13)0.0005 (13)0.0007 (14)
Geometric parameters (Å, º) top
Zn—O31.953 (3)O3—C81.264 (5)
Zn—O1i1.955 (3)C1—C21.485 (5)
Zn—O2ii1.978 (3)C2—C31.388 (5)
Zn—O51.983 (3)C2—C71.390 (5)
O1—C11.254 (5)C3—C41.394 (5)
O1—Zniii1.955 (3)C4—C51.394 (6)
O2—C11.264 (5)C4—C81.495 (5)
O2—Zniv1.978 (3)C5—C61.395 (6)
O4—C81.255 (4)C6—C71.388 (6)
O3—Zn—O1i135.99 (14)C3—C2—C1119.6 (3)
O2ii—Zn—O5106.27 (13)C7—C2—C1120.0 (3)
O1i—Zn—O5105.13 (16)C2—C3—C4119.8 (3)
O3—Zn—O2ii104.04 (13)C5—C4—C3120.2 (3)
O1i—Zn—O2ii102.09 (12)C5—C4—C8119.6 (3)
O3—Zn—O5100.71 (16)C3—C4—C8120.1 (3)
C1—O2—Zniv128.4 (2)C4—C5—C6119.6 (4)
C1—O1—Zniii112.9 (2)C7—C6—C5120.0 (4)
C8—O3—Zn107.9 (2)C6—C7—C2120.3 (4)
O1—C1—O2121.1 (4)O4—C8—O3121.8 (3)
O1—C1—C2117.6 (3)O4—C8—C4120.4 (3)
O2—C1—C2121.2 (3)O3—C8—C4117.8 (3)
C3—C2—C7120.1 (3)
Symmetry codes: (i) x+3/2, y, z+1/2; (ii) x+1, y+1, z+1/2; (iii) x+3/2, y, z1/2; (iv) x+1, y+1, z1/2.
Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
O5—HAO5···O4v0.88 (6)1.83 (6)2.708 (4)173 (6)
O5—HBO5···O4vi0.92 (9)1.90 (9)2.711 (4)145 (8)
Symmetry codes: (v) x, y1, z; (vi) x+1/2, y+1, z.

Experimental details

Crystal data
Chemical formula[Zn(C8H4O4)(H2O)]
Mr247.50
Crystal system, space groupOrthorhombic, Pca21
Temperature (K)298
a, b, c (Å)8.3887 (6), 6.0883 (5), 16.8795 (10)
V3)862.09 (11)
Z4
Radiation typeMo Kα
µ (mm1)2.84
Crystal size (mm)0.68 × 0.42 × 0.19
Data collection
DiffractometerSiemens P4
diffractometer
Absorption correctionIntegration
(SHELXTL; Bruker, 1998)
Tmin, Tmax0.33, 0.59
No. of measured, independent and
observed [I > 2σ(I)] reflections
1797, 1377, 1288
Rint0.016
(sin θ/λ)max1)0.703
Refinement
R[F2 > 2σ(F2)], wR(F2), S 0.034, 0.085, 1.18
No. of reflections1377
No. of parameters135
No. of restraints1
H-atom treatmentH atoms treated by a mixture of independent and constrained refinement
Δρmax, Δρmin (e Å3)0.44, 1.07
Absolute structureFlack (1983)
Absolute structure parameter0.02 (2)

Computer programs: XSCANS (Bruker, 1999), XSCANS, SHELXS97 (Sheldrick, 1997), SHELXL97 (Sheldrick, 1997), SHELXTL/PC (Sheldrick, 1994), X-SEED (Barbour, 1999).

Selected geometric parameters (Å, º) top
Zn—O31.953 (3)O1—C11.254 (5)
Zn—O1i1.955 (3)O2—C11.264 (5)
Zn—O2ii1.978 (3)O4—C81.255 (4)
Zn—O51.983 (3)O3—C81.264 (5)
O3—Zn—O1i135.99 (14)O1i—Zn—O2ii102.09 (12)
O2ii—Zn—O5106.27 (13)O3—Zn—O5100.71 (16)
O1i—Zn—O5105.13 (16)C1—O2—Zniii128.4 (2)
O3—Zn—O2ii104.04 (13)C1—O1—Zniv112.9 (2)
Symmetry codes: (i) x+3/2, y, z+1/2; (ii) x+1, y+1, z+1/2; (iii) x+1, y+1, z1/2; (iv) x+3/2, y, z1/2.
Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
O5—HAO5···O4v0.88 (6)1.83 (6)2.708 (4)173 (6)
O5—HBO5···O4vi0.92 (9)1.90 (9)2.711 (4)145 (8)
Symmetry codes: (v) x, y1, z; (vi) x+1/2, y+1, z.
 

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