Download citation
Download citation
link to html
The molecule of the title compound, [Zn(C2H3O2)2(H2O)2], is located on a twofold axis in the crystal structure. The displacement parameters and the thermal expansion of the crystal show significant anisotropy. This is explained by the two-dimensional hydrogen-bonded structure, with only very weak inter­actions perpendicular to it. Besides the overall mol­ecular motion, there are inter­nal vibrations, which cause the Zn—O(carboxyl­ate) bonds to fail the Hirshfeld rigid-bond test. It is shown that this can be inter­preted in terms of the steric strain in the four-membered chelate ring due to the bidentate carboxyl­ate coordination.

Supporting information

cif

Crystallographic Information File (CIF) https://doi.org/10.1107/S0108270108043242/gz3157sup1.cif
Contains datablocks Ia, Ib, global

hkl

Structure factor file (CIF format) https://doi.org/10.1107/S0108270108043242/gz3157Iasup2.hkl
Contains datablock Ia

hkl

Structure factor file (CIF format) https://doi.org/10.1107/S0108270108043242/gz3157Ibsup3.hkl
Contains datablock Ib

CCDC references: 724184; 724185

Comment top

The room-temperature structure of the title compound, (I), is known from the literature (van Niekerk et al., 1953; Semenenko & Kurdyumov, 1958; Kaduk & Chen, 1996; Ishioka et al., 1997) to form a two-dimensional network by hydrogen bonding, with only very weak interactions in the third direction. The displacement ellipsoids show a large anisotropy and the Zn—O2 bond (Ishioka et al., 1997) fails the Hirshfeld rigid-bond test (Hirshfeld, 1976) by 11σ, as calculated using PLATON (Spek, 2003). To investigate further the anisotropy of this compound, we performed temperature-dependent cell determinations and two complete crystal structure determinations at 110 and 250 K, (Ia) and (Ib), respectively.

The Zn atom is located on a twofold rotation axis and has a distorted octahedral coordination environment, which is formed by four carboxylate O atoms and two water molecules (Fig. 1). The plane of the water molecule has an angle of 33 (2)° with the Zn1—O1 bond in (Ia). This is in contrast with the trigonal coordination with an angle of 0.2 (6)° reported in the literature (Ishioka et al., 1997, 1998). The Zn1—O1 bond to the coordinated water molecule is about 0.15 Å shorter than the Zn1—O2 and Zn1—O3 bonds to the carboxylate group (Tables 1 and 3). At 250 K, the latter Zn—O distances appear similar [(Ib) data set], but at 110 K the difference of about 0.03 Å is significant [(Ia) data set]. A large distortion from an ideal octahedron is found in the O—Zn—O angles, leading to angular distortions (Robinson et al., 1971) of 248.4 (4) and 260.1 (5)°2 for (Ia) and (Ib), respectively.

The bidentate mode, in which both carboxylate O atoms coordinate to the same Zn centre and form a four-membered Zn—O—C—O ring, thus leads to an extremely strained situation, with Zn—O—C angles close to 90° instead of the optimal 120° and O—Zn—O angles close to 60° instead of the octahedral 90° (Tables 1 and 3). The Cambridge Structural Database (CSD, August 2008 update; Allen, 2002) contains 1052 carboxylate complexes of six-coordinated Zn. Only 241 of them have this bidentate coordination mode, of which 225 are not additionally bridging between different metals. The range of Zn—O distances is between 1.9359 (16) Å (Dietzel et al., 2006) and 2.639 (4) Å (Tao et al., 2000). Crystal structures of bidentate carboxylate groups with tetrahedral Zn centres are unknown.

The coordinated water molecule acts as a donor of two intermolecular hydrogen bonds with the carboxylate atoms O2 and O3 as acceptors (Tables 2 and 4). This hydrogen bonding results in an infinite two-dimensional network in the crystallographic bc plane. Between the planes no strong interactions can be detected (van Niekerk et al., 1953). The hydrogen-bonded sheet-like structure is also reflected in the morphology of the crystals, which are shaped as plates where the form {100} has the smallest dimension.

A rigid-body analysis of the displacement parameters using the program THMA11 (Schomaker & Trueblood, 1998) results in a TLS model with weighted R values of 0.112 and 0.113 for (Ia) and (Ib) (R = {[Σ(wΔU)2]/[Σ(wUobs)2]}1/2). The main axes of the L and T tensors are in the ac plane (Fig. 2). In particular, the T tensor is very anisotropic and the T1 axis is close to the a axis. Translational motion in the b and c directions is restricted due to the hydrogen-bonding network, while no such restriction exists in the a direction. Consistent with the rigid-body analysis, the displacement parameters of the individual atoms have their largest components in the direction of the a axis. For Zn1, the anisotropicity, defined as the ratio of the main axes U3obs/U1obs, is 2.57 in (Ia) and 2.32 in (Ib). The average anisotropicity of the whole molecule is 2.15 in (Ia) and 1.94 in (Ib).

While the average anisotropicity is covered by the calculated rigid-body model with U3calc/U1calc of 2.11 in (Ia) and 1.87 in (Ib), the displacement parameters of the individual atoms deviate significantly from this overall model. In other words, there is clearly additional internal motion (Fig. 3). Most affected is atom O2 of the carboxylate group and the O2—Zn1 bonds, which have large differences of mean-square displacement amplitudes (Δ m.s.d.a.'s) along the bond (Hirshfeld, 1976) of 0.0080 (5) and 0.0221 (7) Å2 for (Ia) and (Ib). Internal motion also affects atom O3, but the effect is smaller than for atom O2, with Δ m.s.d.a.'s of 0.0026 (5) and 0.0017 (7) Å2 for (Ia) and (Ib), respectively. These values can be compared with recent bidentate carboxylate complexes of octahedral Zn extracted from Acta Crystallographica (Table 5). Interestingly, all structures have at least one Zn—O(carboxylate) bond where the Hirshfeld rigid-bond test fails, with Δ m.s.d.a. larger than 0.01 Å2 and/or Δ m.s.d.a./σ larger than 5. The similar bond lengths Zn1—O2 and Zn1—O3 observed by Ishioka et al. (1997) and also seen in (Ib) should therefore be considered as an effect of vibrational smearing. It should also be noted that the standard uncertainties for atomic positions and displacement parameters are much higher in Ishioka et al. (1997) compared with (Ia) and (Ib). If (Ia) is compared with (Ib), it can easily be seen that cooling of the crystal does considerably reduce the effect of vibrational smearing, but even the 110 K structure of (Ia) still fails the Hirshfeld test. This might be attributed to the severe strain in the four-membered chelate ring, with bond angles deviating from ideal values (see above). An inspection of the internal movements in the four-membered ring (Fig. 3) suggests that these motions tend to release the strain. In anhydrous zinc acetate (Clegg et al., 1986), there is no failure of the Hirshfeld test because the carboxylate group is bridging, with C—O—Zn angles in the normal range [113.0 (2)–134.6 (2)°], and the Zn is tetrahedral, with O—Zn—O angles also in the normal range [100.8 (1)–117.8 (1)]. The latter conclusion can be generalized on the basis of 25 recently published crystal structures: bridging carboxylate groups usually fulfil the Hirshfeld test for Zn—O bonds in zinc complexes.

The large difference in the intermolecular bonding situation should result in a large anisotropy of the thermal expansion tensor (Salud et al., 1998). We therefore performed a temperature-dependent study of the cell parameters by cooling the crystal from 290 to 110 K in steps of 20 K (Fig. 4). To minimize diffractometer errors in the cell determinations, we used the Phi/Phi-Chi routine (Duisenberg et al., 2000) and kept the position of the detector fixed. The largest change is found for the a axis, which is the direction of the weakest intermolecular interactions. More details are obtained from an analysis of the thermal expansion tensor. Usually, the thermal expansion tensor is expressed in a Cartesian coordinate system, resulting in a symmetric second-rank tensor. With monoclinic symmetry, two off-diagonal terms of this tensor become zero, with one eigenvector parallel to the crystallographic twofold axis. The program STRAIN (Ohashi, 1982) was used for the calculation of the tensors and the results are shown in Tables 6 and 7. The eigenvalue of α1 has the largest magnitude and is positive over the whole temperature range. α1 is nearly collinear with the a axis. This can also be graphically visualized by a plot of the strain ellipsoid of the thermal expansion (Fig. 5). α2 and α3 have much smaller magnitudes. α3 is parallel to the b axis by symmetry (see above) and has a negative sign over the whole temperature range. α2 is also negative for most temperature changes. We can therefore conclude that the crystal has a biaxial negative thermal expansion as a consequence of the hydrogen-bonding pattern.

An alternative explanation for large displacement parameters is the choice of a too high space group symmetry. The structure is then refined as an average and the corresponding increased displacement parameters are artefacts. Therefore, we performed a careful analysis of the symmetry. The crystal structure of (I) is best described in the centrosymmetric space group C2/c. In the literature there is a report of a refinement in Cc, which was unsuccessful due to abnormalities in the temperature factors and the bond distances, which caused the authors to choose C2/c (Ishioka et al., 1998). If the structure is solved in P1, the routine ADDSYM in PLATON (Spek, 2003) and the space group algorithm of SUPERFLIP (Palatinus & van der Lee, 2008) strongly suggest a transformation to C2/c. The correctness of C2/c is further proven by the least-squares refinement. The weakest reflections, which are most sensitive to the choice of the correct space group (Walker et al., 1999), have a scale factor K = [mean(Fo2)/mean(Fc2)] close to 1.0 (Table 8). If the real space group were noncentrosymmetric, a much higher value of K would be expected.

Nevertheless, the intensity statistics are noncentrosymmetric. <|E2-1|> for all reflections in (Ia), as calculated with SIR97 (Altomare et al., 1999), is 0.798, with theoretical values of 0.968 for centrosymmetric and 0.736 for noncentrosymmetric structures. A cumulative n(z) distribution is also indicative of a noncentrosymmetric structure (Fig. 6). A closer look shows that the Zn atoms on the special positions are the cause of the noncentrosymmetric intensity statistics. If <|E2-1|> is determined from calculated structure factors based only on Zn atoms, the result is 0.553, while calculated structure factors from only the C, H and O atoms lead to <|E2-1|> of 0.930.

Using the routine WTANAL of the WinGX package (Farrugia, 1999), it is possible to plot the mean intensities for the three principal directions of the crystal (Fig. 7). While similar behaviour is found for the b* and c* directions, the intensity decay with resolution is significantly stronger in the a* direction. This finding is consistent with the directions of the T tensor of the rigid-body analysis (see above). In accordance with this decay of Bragg intensities in the a* direction, we expect the presence of diffuse intensity in this direction. This diffuse intensity can indeed be detected, but the effect is very weak; it was necessary to collect overexposed diffraction images at 250 K, different from the images of (Ib), to make the streaks visible.

Experimental top

Crystals of (I) were unintentionally obtained by slow evaporation of an aqueous solution of zinc acetate in the presence of urea in a molar ratio of 1:2 at room temperature.

Refinement top

Because many effects discussed in this paper might be influenced by the correctness of the absorption correction, special care was taken to index the crystal faces and measure their distances. This information was used for the numerical absorption correction in the program SADABS (Sheldrick, 2008a), which additionally refines spherical harmonics functions based on multiple measured reflections to improve further the reliability of the data.

The O-bound H atoms of the water molecule were located in a difference Fourier map and refined freely with isotropic displacement parameters. The difference density map in the plane of the methyl H atoms does not show distinct maxima. The methyl H atoms were therefore introduced in calculated positions and refined with an AFIX 137 card (SHELXL97; Sheldrick, 1998b) using a large number of refinement cycles [Please give specific constraints used].

Computing details top

For both compounds, data collection: COLLECT (Nonius, 1999); cell refinement: PEAKREF (Schreurs, 2008); data reduction: PIXEL15 (Xian et al., 2006) and SADABS (Sheldrick, 2008a); program(s) used to solve structure: initial coordinates from Ishioka et al. (1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008b); molecular graphics: PLATON (Spek, 2003); software used to prepare material for publication: manual editing of SHELXL97 (Sheldrick, 2008b) output.

Figures top
[Figure 1] Fig. 1. Displacement ellipsoid plots and atomic numbering schemes for (Ia) at 110 K and (Ib) at 250 K. Ellipsoids are drawn at the 50% probability level and H atoms are shown as small spheres of arbitrary radii.
[Figure 2] Fig. 2. L and T tensors obtained from a rigid-body analysis for (Ia) at 110 K, and (Ib) at 250 K. Views along the crystallographic b axis (same perspective as in Fig. 1). The eigenvalues of the L tensor are 3.24, 1.84 and 1.82°2 for (Ia), and 7.20, 4.91 and 3.20°2 for (Ib). The eigenvalues of the T tensor are 0.02309, 0.01048 and 0.00954 Å2 for (Ia), and 0.05150, 0.02877 and 0.02329 Å2 for (Ib). The eigenvectors L1 are in the ac plane and have angles to a of 57.93 and 74.25° for (Ia) and (Ib), respectively. The eigenvectors T1 are also in the ac plane and have angles to a of 7.45 and 7.72° for (Ia) and (Ib), respectively. The S tensors in (Ia) and (Ib) are (-0.00092, 0, 0.00037 / 0, 0.00079, 0 / 0.00049, 0, 0.00013) and (-0.00136, 0, 0.00055 / 0, 0.00152, 0 / 0.00090, 0, -0.00016)rad-Å.
[Figure 3] Fig. 3. Peanut plots (Hummel et al., 1990) of (Ia) at 110 K and (Ib) at 250 K, showing the difference between the measured displacement parameters and the TLS model from the program THMA11 (Schomaker & Trueblood, 1998). A scale factor of 3.08 was used for the root-mean-square surfaces. Blue lines indicate positive differences and red lines negative ones [NB Colour will not be visible in the printed version of the journal - please revise].
[Figure 4] Fig. 4. (a) Unit-cell length a (top), b (bottom) and c (middle), (b) cell angle β and (c) cell volume V as a function of temperature during cooling from 290 to 110 K at a cooling rate of 120 K h-1. Each cell determination is based on a post-refinement (Schreurs, 2008) of 147–150 individual reflections. (a = 13.539 + 2.97 × 10 -3 T, b = 5.397 + 0.24 × 10 -3 T, c = 10.879 + 0.29 × 10 -3 T, V = 789.57 + 0.134 T).
[Figure 5] Fig. 5. Strain ellipsoid of the thermal expansion between (Ia) and (Ib). The strain ellipsoid is defined by the equation X12/(1+α1ΔT)2 + X22/(1+α2ΔT)2 + X32/(1+α3ΔT)2 = 1 (Küppers, 2003). View along the crystallographic b axis (same perspective as in Fig. 1). Shown in red is the deviation (greatly exaggerated) from isotropic behaviour (indicated in black). The corresponding eigenvalues α of the strain tensor are 253.9 (19.56° to a), -38.3 (27.51° to c) and -51.1 (parallel to b) 10 -6 K-1. [NB Colour will not be visible in the printed version of the journal - please revise]
[Figure 6] Fig. 6. Cumulative n(z) statistics for (Ia), as calculated with the program SIR97 (Altomare et al., 1999). The experimental values are given as black circles. The theoretical curve for noncentrosymmetric structures is shown as a solid line and that for centrosymmetric structures as a dashed line.
[Figure 7] Fig. 7. Mean intensities versus increasing index h (green), k (red), and l (blue) for (Ia) and (Ib), as calculated using the routine WTANAL in WinGX (Farrugia, 1999). [NB Colour will not be visible in the printed version of the journal - please revise]
(Ia) bis(acetato-κ2O,O')diaquazinc(II) top
Crystal data top
[Zn(C2H3O2)2(H2O)2]F(000) = 448
Mr = 219.49Dx = 1.807 Mg m3
Monoclinic, C2/cMo Kα radiation, λ = 0.71073 Å
Hall symbol: -C 2ycCell parameters from 3489 reflections
a = 13.8556 (2) Åθ = 1.9–27.5°
b = 5.38096 (7) ŵ = 3.03 mm1
c = 10.92487 (14) ÅT = 110 K
β = 97.942 (1)°Plate, colourless
V = 806.71 (2) Å30.42 × 0.30 × 0.06 mm
Z = 4
Data collection top
Nonius KappaCCD area-detector
diffractometer
925 independent reflections
Radiation source: rotating anode898 reflections with I > 2σ(I)
Graphite monochromatorRint = 0.015
ϕ and ω scansθmax = 27.5°, θmin = 3.0°
Absorption correction: numerical
(SADABS; Sheldrick, 2008a)
h = 1818
Tmin = 0.408, Tmax = 0.856k = 66
6788 measured reflectionsl = 1414
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)] = 0.016Hydrogen site location: inferred from neighbouring sites
wR(F2) = 0.045H atoms treated by a mixture of independent and constrained refinement
S = 1.10 w = 1/[σ2(Fo2) + (0.0247P)2 + 1.0186P]
where P = (Fo2 + 2Fc2)/3
925 reflections(Δ/σ)max = 0.004
60 parametersΔρmax = 0.35 e Å3
0 restraintsΔρmin = 0.47 e Å3
Crystal data top
[Zn(C2H3O2)2(H2O)2]V = 806.71 (2) Å3
Mr = 219.49Z = 4
Monoclinic, C2/cMo Kα radiation
a = 13.8556 (2) ŵ = 3.03 mm1
b = 5.38096 (7) ÅT = 110 K
c = 10.92487 (14) Å0.42 × 0.30 × 0.06 mm
β = 97.942 (1)°
Data collection top
Nonius KappaCCD area-detector
diffractometer
925 independent reflections
Absorption correction: numerical
(SADABS; Sheldrick, 2008a)
898 reflections with I > 2σ(I)
Tmin = 0.408, Tmax = 0.856Rint = 0.015
6788 measured reflections
Refinement top
R[F2 > 2σ(F2)] = 0.0160 restraints
wR(F2) = 0.045H atoms treated by a mixture of independent and constrained refinement
S = 1.10Δρmax = 0.35 e Å3
925 reflectionsΔρmin = 0.47 e Å3
60 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
Zn10.00000.11907 (4)0.25000.01426 (9)
O10.08735 (8)0.1237 (2)0.14848 (10)0.0180 (2)
H1O0.0966 (15)0.250 (5)0.175 (2)0.029 (6)*
H2O0.0823 (16)0.139 (4)0.081 (2)0.028 (6)*
O20.10704 (8)0.42204 (19)0.26068 (9)0.0191 (2)
O30.06989 (8)0.2111 (2)0.09043 (9)0.0195 (2)
C10.11449 (10)0.3916 (2)0.14763 (13)0.0152 (3)
C20.17317 (11)0.5694 (3)0.08262 (14)0.0209 (3)
H2A0.13340.71530.05590.031*
H2B0.19370.48780.01030.031*
H2C0.23080.62170.13910.031*
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
Zn10.02348 (14)0.00915 (13)0.01049 (12)0.0000.00356 (8)0.000
O10.0309 (6)0.0123 (5)0.0110 (5)0.0039 (4)0.0040 (4)0.0004 (4)
O20.0316 (6)0.0137 (5)0.0124 (5)0.0019 (4)0.0045 (4)0.0004 (4)
O30.0290 (5)0.0159 (5)0.0142 (5)0.0061 (4)0.0048 (4)0.0012 (4)
C10.0189 (6)0.0130 (7)0.0136 (6)0.0028 (5)0.0018 (5)0.0019 (5)
C20.0253 (7)0.0201 (7)0.0176 (7)0.0056 (6)0.0040 (6)0.0016 (6)
Geometric parameters (Å, º) top
Zn1—O12.0076 (11)O1—H1O0.76 (2)
Zn1—O1i2.0076 (11)O1—H2O0.76 (2)
Zn1—O3i2.1653 (10)O2—C11.2641 (18)
Zn1—O32.1653 (10)O3—C11.2685 (17)
Zn1—O22.1962 (11)C1—C21.4970 (19)
Zn1—O2i2.1962 (11)C2—H2A0.9800
Zn1—C1i2.5313 (14)C2—H2B0.9800
Zn1—C12.5313 (14)C2—H2C0.9800
O1—Zn1—O1i98.81 (7)O3i—Zn1—C1126.91 (4)
O1—Zn1—O3i106.92 (4)O3—Zn1—C130.07 (4)
O1i—Zn1—O3i90.37 (4)O2—Zn1—C129.96 (4)
O1—Zn1—O390.37 (4)O2i—Zn1—C190.36 (4)
O1i—Zn1—O3106.92 (4)C1i—Zn1—C1109.20 (6)
O3i—Zn1—O3153.57 (6)Zn1—O1—H1O119.4 (16)
O1—Zn1—O2149.71 (4)Zn1—O1—H2O118.7 (16)
O1i—Zn1—O295.88 (4)H1O—O1—H2O109 (2)
O3i—Zn1—O299.29 (4)C1—O2—Zn189.86 (8)
O3—Zn1—O259.95 (4)C1—O3—Zn191.15 (8)
O1—Zn1—O2i95.88 (4)O2—C1—O3118.73 (13)
O1i—Zn1—O2i149.71 (4)O2—C1—C2120.24 (13)
O3i—Zn1—O2i59.95 (4)O3—C1—C2121.01 (13)
O3—Zn1—O2i99.29 (4)O2—C1—Zn160.18 (7)
O2—Zn1—O2i84.14 (6)O3—C1—Zn158.79 (7)
O1—Zn1—C1i104.73 (4)C2—C1—Zn1174.02 (10)
O1i—Zn1—C1i119.98 (5)C1—C2—H2A109.5
O3i—Zn1—C1i30.07 (4)C1—C2—H2B109.5
O3—Zn1—C1i126.91 (4)H2A—C2—H2B109.5
O2—Zn1—C1i90.36 (4)C1—C2—H2C109.5
O2i—Zn1—C1i29.96 (4)H2A—C2—H2C109.5
O1—Zn1—C1119.98 (5)H2B—C2—H2C109.5
O1i—Zn1—C1104.73 (4)
O1—Zn1—O2—C19.34 (13)Zn1—O3—C1—O25.64 (13)
O1i—Zn1—O2—C1109.46 (8)Zn1—O3—C1—C2173.02 (12)
O3i—Zn1—O2—C1159.20 (8)O1—Zn1—C1—O2174.58 (8)
O3—Zn1—O2—C13.30 (8)O1i—Zn1—C1—O275.88 (9)
O2i—Zn1—O2—C1100.99 (9)O3i—Zn1—C1—O226.00 (10)
C1i—Zn1—O2—C1130.35 (8)O3—Zn1—C1—O2174.30 (13)
O1—Zn1—O3—C1170.38 (9)O2i—Zn1—C1—O277.57 (9)
O1i—Zn1—O3—C190.29 (9)C1i—Zn1—C1—O253.80 (7)
O3i—Zn1—O3—C138.55 (8)O1—Zn1—C1—O311.12 (10)
O2—Zn1—O3—C13.28 (8)O1i—Zn1—C1—O398.42 (9)
O2i—Zn1—O3—C174.35 (8)O3i—Zn1—C1—O3159.70 (6)
C1i—Zn1—O3—C161.54 (12)O2—Zn1—C1—O3174.30 (13)
Zn1—O2—C1—O35.56 (13)O2i—Zn1—C1—O3108.13 (8)
Zn1—O2—C1—C2173.11 (12)C1i—Zn1—C1—O3131.90 (9)
Symmetry code: (i) x, y, z+1/2.
Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
O1—H1O···O2ii0.76 (2)1.91 (3)2.6663 (15)174 (2)
O1—H2O···O3iii0.76 (2)1.94 (2)2.6956 (15)175 (2)
Symmetry codes: (ii) x, y1, z+1/2; (iii) x, y, z.
(Ib) bis(acetato-κ2O,O')diaquazinc(II) top
Crystal data top
[Zn(C2H3O2)2(H2O)2]F(000) = 448
Mr = 219.49Dx = 1.767 Mg m3
Monoclinic, C2/cMo Kα radiation, λ = 0.71073 Å
Hall symbol: -C 2ycCell parameters from 3506 reflections
a = 14.2904 (5) Åθ = 1.9–27.5°
b = 5.34245 (11) ŵ = 2.96 mm1
c = 10.9616 (2) ÅT = 250 K
β = 99.590 (1)°Plate, colourless
V = 825.17 (4) Å30.42 × 0.30 × 0.06 mm
Z = 4
Data collection top
Nonius KappaCCD area-detector
diffractometer
940 independent reflections
Radiation source: rotating anode888 reflections with I > 2σ(I)
Graphite monochromatorRint = 0.017
ϕ and ω scansθmax = 27.5°, θmin = 2.9°
Absorption correction: numerical
(SADABS; Sheldrick, 2008a)
h = 1818
Tmin = 0.405, Tmax = 0.864k = 66
6929 measured reflectionsl = 1414
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)] = 0.020Hydrogen site location: inferred from neighbouring sites
wR(F2) = 0.056H atoms treated by a mixture of independent and constrained refinement
S = 1.10 w = 1/[σ2(Fo2) + (0.0338P)2 + 0.4592P]
where P = (Fo2 + 2Fc2)/3
940 reflections(Δ/σ)max = 0.005
60 parametersΔρmax = 0.29 e Å3
0 restraintsΔρmin = 0.30 e Å3
Crystal data top
[Zn(C2H3O2)2(H2O)2]V = 825.17 (4) Å3
Mr = 219.49Z = 4
Monoclinic, C2/cMo Kα radiation
a = 14.2904 (5) ŵ = 2.96 mm1
b = 5.34245 (11) ÅT = 250 K
c = 10.9616 (2) Å0.42 × 0.30 × 0.06 mm
β = 99.590 (1)°
Data collection top
Nonius KappaCCD area-detector
diffractometer
940 independent reflections
Absorption correction: numerical
(SADABS; Sheldrick, 2008a)
888 reflections with I > 2σ(I)
Tmin = 0.405, Tmax = 0.864Rint = 0.017
6929 measured reflections
Refinement top
R[F2 > 2σ(F2)] = 0.0200 restraints
wR(F2) = 0.056H atoms treated by a mixture of independent and constrained refinement
S = 1.10Δρmax = 0.29 e Å3
940 reflectionsΔρmin = 0.30 e Å3
60 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
Zn10.00000.12885 (4)0.25000.03453 (12)
O10.08474 (11)0.1154 (2)0.14588 (13)0.0419 (3)
H1O0.0962 (18)0.229 (5)0.171 (2)0.055 (8)*
H2O0.0805 (17)0.136 (4)0.076 (2)0.051 (7)*
O20.10495 (11)0.4302 (2)0.26044 (11)0.0459 (3)
O30.07017 (10)0.2153 (3)0.09191 (11)0.0464 (3)
C10.11407 (13)0.3949 (3)0.14928 (15)0.0353 (3)
C20.17375 (15)0.5666 (4)0.08771 (18)0.0488 (4)
H2A0.13810.71720.06150.073*
H2B0.19160.48400.01620.073*
H2C0.23050.61050.14540.073*
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
Zn10.05210 (19)0.02247 (16)0.02942 (16)0.0000.00798 (11)0.000
O10.0673 (9)0.0299 (7)0.0291 (6)0.0097 (6)0.0097 (6)0.0005 (5)
O20.0757 (9)0.0321 (6)0.0319 (6)0.0065 (6)0.0151 (6)0.0012 (5)
O30.0667 (8)0.0389 (7)0.0354 (6)0.0148 (6)0.0140 (6)0.0033 (5)
C10.0444 (9)0.0301 (8)0.0316 (8)0.0057 (6)0.0068 (6)0.0032 (6)
C20.0573 (11)0.0470 (10)0.0431 (10)0.0132 (9)0.0114 (8)0.0008 (8)
Geometric parameters (Å, º) top
Zn1—O12.0027 (13)O1—H1O0.69 (3)
Zn1—O1i2.0027 (13)O1—H2O0.78 (3)
Zn1—O2i2.1904 (15)O2—C11.261 (2)
Zn1—O22.1904 (15)O3—C11.257 (2)
Zn1—O3i2.1910 (12)C1—C21.489 (2)
Zn1—O32.1911 (12)C2—H2A0.9700
Zn1—C1i2.5488 (17)C2—H2B0.9700
Zn1—C12.5489 (17)C2—H2C0.9700
O1—Zn1—O1i98.70 (8)O2i—Zn1—C192.82 (5)
O1—Zn1—O3i105.96 (6)O2—Zn1—C129.65 (5)
O1i—Zn1—O3i89.97 (5)O3i—Zn1—C1129.43 (5)
O1—Zn1—O389.97 (5)O3—Zn1—C129.53 (5)
O1i—Zn1—O3105.96 (6)C1i—Zn1—C1112.20 (7)
O3i—Zn1—O3155.68 (8)Zn1—O1—H1O120 (2)
O1—Zn1—O2148.47 (5)Zn1—O1—H2O120.5 (17)
O1i—Zn1—O296.05 (6)H1O—O1—H2O109 (2)
O2i—Zn1—O3101.74 (5)C1—O2—Zn191.13 (11)
O2—Zn1—O359.13 (5)C1—O3—Zn191.22 (10)
O1—Zn1—O2i96.05 (6)O3—C1—O2118.33 (16)
O1i—Zn1—O2i148.48 (5)O3—C1—C2121.31 (16)
O2i—Zn1—O3i59.13 (5)O2—C1—C2120.34 (16)
O2—Zn1—O3i101.74 (5)O3—C1—Zn159.25 (9)
O2i—Zn1—O285.37 (7)O2—C1—Zn159.23 (10)
O1—Zn1—C1i103.92 (6)C2—C1—Zn1174.93 (13)
O1i—Zn1—C1i119.09 (6)C1—C2—H2A109.5
O2i—Zn1—C1i29.65 (5)C1—C2—H2B109.5
O2—Zn1—C1i92.82 (5)H2A—C2—H2B109.5
O3i—Zn1—C1i29.53 (5)C1—C2—H2C109.5
O3—Zn1—C1i129.43 (5)H2A—C2—H2C109.5
O1—Zn1—C1119.08 (6)H2B—C2—H2C109.5
O1i—Zn1—C1103.92 (6)
O1—Zn1—O2—C19.98 (17)Zn1—O2—C1—O34.47 (17)
O1i—Zn1—O2—C1107.63 (11)Zn1—O2—C1—C2174.14 (15)
O2i—Zn1—O2—C1104.00 (11)O1—Zn1—C1—O310.53 (13)
O3i—Zn1—O2—C1161.14 (10)O1i—Zn1—C1—O397.90 (11)
O3—Zn1—O2—C12.63 (10)O2i—Zn1—C1—O3109.05 (11)
C1i—Zn1—O2—C1132.72 (10)O2—Zn1—C1—O3175.42 (17)
O1—Zn1—O3—C1170.81 (11)O3i—Zn1—C1—O3160.39 (8)
O1i—Zn1—O3—C190.15 (11)C1i—Zn1—C1—O3132.16 (12)
O2i—Zn1—O3—C174.64 (11)O1—Zn1—C1—O2174.05 (10)
O2—Zn1—O3—C12.64 (10)O1i—Zn1—C1—O277.52 (11)
O3i—Zn1—O3—C139.01 (10)O2i—Zn1—C1—O275.53 (12)
C1i—Zn1—O3—C162.69 (15)O3i—Zn1—C1—O224.19 (13)
Zn1—O3—C1—O24.47 (17)O3—Zn1—C1—O2175.42 (17)
Zn1—O3—C1—C2174.12 (16)C1i—Zn1—C1—O252.42 (9)
Symmetry code: (i) x, y, z+1/2.
Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
O1—H1O···O2ii0.69 (3)1.98 (3)2.6702 (19)169 (3)
O1—H2O···O3iii0.78 (3)1.92 (3)2.7023 (18)175 (2)
Symmetry codes: (ii) x, y1, z+1/2; (iii) x, y, z.

Experimental details

(Ia)(Ib)
Crystal data
Chemical formula[Zn(C2H3O2)2(H2O)2][Zn(C2H3O2)2(H2O)2]
Mr219.49219.49
Crystal system, space groupMonoclinic, C2/cMonoclinic, C2/c
Temperature (K)110250
a, b, c (Å)13.8556 (2), 5.38096 (7), 10.92487 (14)14.2904 (5), 5.34245 (11), 10.9616 (2)
β (°) 97.942 (1) 99.590 (1)
V3)806.71 (2)825.17 (4)
Z44
Radiation typeMo KαMo Kα
µ (mm1)3.032.96
Crystal size (mm)0.42 × 0.30 × 0.060.42 × 0.30 × 0.06
Data collection
DiffractometerNonius KappaCCD area-detector
diffractometer
Nonius KappaCCD area-detector
diffractometer
Absorption correctionNumerical
(SADABS; Sheldrick, 2008a)
Numerical
(SADABS; Sheldrick, 2008a)
Tmin, Tmax0.408, 0.8560.405, 0.864
No. of measured, independent and
observed [I > 2σ(I)] reflections
6788, 925, 898 6929, 940, 888
Rint0.0150.017
(sin θ/λ)max1)0.6500.649
Refinement
R[F2 > 2σ(F2)], wR(F2), S 0.016, 0.045, 1.10 0.020, 0.056, 1.10
No. of reflections925940
No. of parameters6060
H-atom treatmentH atoms treated by a mixture of independent and constrained refinementH atoms treated by a mixture of independent and constrained refinement
Δρmax, Δρmin (e Å3)0.35, 0.470.29, 0.30

Computer programs: COLLECT (Nonius, 1999), PEAKREF (Schreurs, 2008), PIXEL15 (Xian et al., 2006) and SADABS (Sheldrick, 2008a), initial coordinates from Ishioka et al. (1997), PLATON (Spek, 2003), manual editing of SHELXL97 (Sheldrick, 2008b) output.

Selected geometric parameters (Å, º) for (Ia) top
Zn1—O12.0076 (11)O2—C11.2641 (18)
Zn1—O32.1653 (10)O3—C11.2685 (17)
Zn1—O22.1962 (11)
O1—Zn1—O1i98.81 (7)O1—Zn1—O2i95.88 (4)
O1—Zn1—O3i106.92 (4)O3—Zn1—O2i99.29 (4)
O1—Zn1—O390.37 (4)O2—Zn1—O2i84.14 (6)
O3i—Zn1—O3153.57 (6)C1—O2—Zn189.86 (8)
O1—Zn1—O2149.71 (4)C1—O3—Zn191.15 (8)
O3—Zn1—O259.95 (4)O2—C1—O3118.73 (13)
Symmetry code: (i) x, y, z+1/2.
Hydrogen-bond geometry (Å, º) for (Ia) top
D—H···AD—HH···AD···AD—H···A
O1—H1O···O2ii0.76 (2)1.91 (3)2.6663 (15)174 (2)
O1—H2O···O3iii0.76 (2)1.94 (2)2.6956 (15)175 (2)
Symmetry codes: (ii) x, y1, z+1/2; (iii) x, y, z.
Selected geometric parameters (Å, º) for (Ib) top
Zn1—O12.0027 (13)O2—C11.261 (2)
Zn1—O22.1904 (15)O3—C11.257 (2)
Zn1—O32.1911 (12)
O1—Zn1—O1i98.70 (8)O1—Zn1—O2i96.05 (6)
O1—Zn1—O3i105.96 (6)O2—Zn1—O3i101.74 (5)
O1—Zn1—O389.97 (5)O2i—Zn1—O285.37 (7)
O3i—Zn1—O3155.68 (8)C1—O2—Zn191.13 (11)
O1—Zn1—O2148.47 (5)C1—O3—Zn191.22 (10)
O2—Zn1—O359.13 (5)O3—C1—O2118.33 (16)
Symmetry code: (i) x, y, z+1/2.
Hydrogen-bond geometry (Å, º) for (Ib) top
D—H···AD—HH···AD···AD—H···A
O1—H1O···O2ii0.69 (3)1.98 (3)2.6702 (19)169 (3)
O1—H2O···O3iii0.78 (3)1.92 (3)2.7023 (18)175 (2)
Symmetry codes: (ii) x, y1, z+1/2; (iii) x, y, z.
Hirshfeld rigid-bond test (Hirshfeld, 1976) of the Zn—O(carboxylate) bonds. Comparison of (Ia), (Ib) and ZNAQAC03 (Ishioka et al., 1997) with zinc carboxylate structures extracted from Acta Crystallographica. The structures are identified by their refcode in the Cambridge Structural Database (Allen, 2002). Only the maximum m.s.d.a. values are given. Structures FAXPEA and UMIBIB have been omitted because of disorder top
CSD refcodeSite symmetry ZnT (K)Δ m.s.d.a. (Å2)Δ m.s.d.a./σ
(Ia)21100.0080 (5)16.06
(Ib)22500.0221 (7)31.62
ZNAQAC0322920.0272 (25)10.87
ACOGIJ0112980.0141 (12)11.72
CEHCAT0121600.0047 (9)5.18
CICHOM22930.0276 (12)22.99
EDUNOH22920.0050 (9)5.61
EXOZUM12930.0260 (27)9.62
EYOVOD12930.0276 (19)14.55
EYOVUJ12930.0102 (17)6.01
FERQID12930.0244 (8)30.48
GAVPAV12950.0350 (37)9.47
GETZOV12930.0134 (24)5.58
GIMHUG12630.0133 (30)4.43
HAMMOY12930.0368 (14)26.30
HAYTOR12950.0357 (14)25.49
HAYXIP12340.0120 (14)8.57
HIQDIV12950.0046 (8)5.81
HIQSUW12930.0174 (14)12.44
KIWNOU22940.0109 (27)4.04
KIWNUA12940.0448 (16)27.97
KIYSEQ22990.0151 (17)8.91
JEWDIZ12930.0090 (8)11.19
NEQLIF12980.0122 (34)3.59
NIWNOX12950.0101 (14)7.22
PAHSOH12930.0289 (18)16.03
PESKEE11530.0208 (50)4.16
REHDIS12920.0191 (23)8.29
VAVFUU0212980.0279 (34)8.21
VIQLEN12930.0275 (17)16.20
WEJMOO12920.0103 (17)6.07
WIZRAZ12930.0596 (20)29.80
XIYJAR12980.0104 (18)5.80
XIYJEV12960.0125 (15)8.32
XIYNOJ12960.0251 (14)17.94
YASMOV12950.0211 (16)13.19
Tensor components of the thermal expansion (10 -6 K-1) in the cartesian xyz coordinate system (α12, α23 = 0) top
T (K)α11α22α33α13
290-270171.83-25.0326.38-66.61
270-250169.18-33.1623.65-71.36
250-230174.96-26.4025.26-88.10
230-210177.31-44.7227.88-93.61
210-190178.82-33.6619.71-98.09
190-170174.93-29.9941.78-80.03
170-150189.30-75.0018.95-143.43
150-130199.49-71.5537.89-146.19
130-110228.14-79.437.33-178.73
Eigenvalues (10 -6 K-1) of the thermal expansion tensor and angles of the eigenvectors with the crystallographic axes top
T (K)Principal axisEigenvalueAngle with aAngle with bAngle with c
290-270α1198 (3)11.5 (5)90111.2 (5)
α20(3)78.5 (5)9021.2 (5)
α3-25 (4)9018090
270-250α1198 (3)12.6 (5)90112.2 (5)
α2-6(2)77.4 (5)9022.2 (5)
α3-33 (4)9018090
250-230α1216 (4)15.4 (5)90114.8 (5)
α2-15 (3)74.6 (5)9024.8 (5)
α3-26 (4)9018090
230-210α1222 (4)16.4 (6)90115.7 (6)
α2-17 (4)73.6 (6)9025.7 (6)
α3-44 (4)9018090
210-190α1226 (4)16.4 (5)90115.5 (5)
α2-27 (4)73.6 (5)9025.5 (5)
α3-34 (4)9018090
190-170α1213 (4)16.2 (7)90115.1 (7)
α24(4)73.8 (7)9025.1 (7)
α3-30 (5)9018090
170-150α1271 (3)21.0 (5)90119.7 (5)
α2-62 (4)69.0 (5)9029.7 (5)
α3-75 (4)9018090
150-130α1286 (3)22.2 (5)90120.5 (5)
α2-48 (4)67.8 (5)9030.5 (5)
α3-72 (4)9018090
130-110α1328 (4)21.2 (4)90119.2 (4)
α2-79 (4)90090
α3-92 (4)68.8 (4)9029.2 (4)
Scale factor K = [mean(Fo2)/mean(Fc2)] versus intensity for (Ia) top
Fc/Fc(max)No. refl.K
<0.039941.050
<0.076911.020
<0.110940.996
<0.140910.985
<0.170940.999
<0.200920.999
<0.241911.006
<0.304941.000
<0.413911.004
<1.000931.000
 

Follow Acta Cryst. C
Sign up for e-alerts
Follow Acta Cryst. on Twitter
Follow us on facebook
Sign up for RSS feeds