metal-organic compounds
A second modification of poly[diaquadi-μ-citrato(3−)-trizinc(II)]
aDepartment of Chemistry, Northeast Normal University, Changchun 130024, People's Republic of China
*Correspondence e-mail: wangenbo@public.cc.jl.cn
A second modification of the zinc(II) coordination polymer with citric acid, [Zn3(C6H5O7)2(H2O)2]n or [Zn(citrate)2(H2O)2], has been synthesized under hydrothermal conditions by reacting zinc acetate with citric acid. The structure contains two unique Zn atoms, one with a distorted octahedral coordination and located on an inversion centre, and one with a distorted tetrahedral coordination. The ZnO6 and ZnO4 units are linked into layers extending parallel to (010).
Related literature
For the structure of the first polymorph, see: Wu (2008). For general background, see Bourne et al. (2001); Yaghi et al. (1996). Biologically relevant transition-metal citrate compounds have bee reported by Liu et al. (2005) and Xie et al. (2005).
Experimental
Crystal data
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Refinement
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Data collection: RAPID-AUTO (Rigaku, 1998); cell RAPID-AUTO; data reduction: RAPID-AUTO; 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.
Supporting information
10.1107/S1600536808028456/rk2084sup1.cif
contains datablocks I, global. DOI:Structure factors: contains datablock I. DOI: 10.1107/S1600536808028456/rk2084Isup2.hkl
Compound (1) was prepared from a weak acidic mixture of zinc acetate (0.255 g, 1 mmol), citric acid (0.49 g, 1.5 mmol) and a 15 ml alcohol/water mixture, which was sealed in a 30 ml Teflon-lined steel vessel and kept at 433 K under autogenously pressure for three d. After cooling, yellow crystals were isolated and air-dried with a yield of approximately 63%.
All H-atoms bound to carbon were refined using a riding model with d(C—H) = 0.97 Å and Uiso(H) = 1.5Ueq(C). H atoms of the water molecule were located in difference maps and refined isotropically with d(O—H) = 0.85 Å and Uiso(H) = 1.5Ueq(O).
Data collection: RAPID-AUTO (Rigaku, 1998); cell
RAPID-AUTO (Rigaku, 1998); data reduction: RAPID-AUTO (Rigaku, 1998); 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).[Zn3(C6H5O7)2(H2O)2] | Z = 1 |
Mr = 610.34 | F(000) = 304 |
Triclinic, P1 | Dx = 2.312 Mg m−3 |
Hall symbol: -P 1 | Mo Kα radiation, λ = 0.71073 Å |
a = 6.4649 (13) Å | Cell parameters from 2026 reflections |
b = 7.2666 (15) Å | θ = 3.3–27.5° |
c = 9.6951 (19) Å | µ = 4.16 mm−1 |
α = 85.27 (3)° | T = 298 K |
β = 77.31 (3)° | Block, yellow |
γ = 80.99 (3)° | 0.28 × 0.26 × 0.22 mm |
V = 438.29 (15) Å3 |
Rigaku R-AXIS RAPID IP diffractometer | 2004 independent reflections |
Radiation source: fine-focus sealed tube | 1763 reflections with I > 2σ(I) |
Graphite monochromator | Rint = 0.029 |
ω–scans | θmax = 27.5°, θmin = 3.3° |
Absorption correction: multi-scan ABSCOR (Higashi, 1995) | h = −8→8 |
Tmin = 0.389, Tmax = 0.461 | k = −9→9 |
4339 measured reflections | l = −12→12 |
Refinement on F2 | Primary atom site location: structure-invariant direct methods |
Least-squares matrix: full | Secondary atom site location: difference Fourier map |
R[F2 > 2σ(F2)] = 0.027 | Hydrogen site location: inferred from neighbouring sites |
wR(F2) = 0.066 | H atoms treated by a mixture of independent and constrained refinement |
S = 1.04 | w = 1/[σ2(Fo2) + (0.0291P)2 + 0.3186P] where P = (Fo2 + 2Fc2)/3 |
2004 reflections | (Δ/σ)max < 0.001 |
146 parameters | Δρmax = 0.87 e Å−3 |
0 restraints | Δρmin = −0.60 e Å−3 |
[Zn3(C6H5O7)2(H2O)2] | γ = 80.99 (3)° |
Mr = 610.34 | V = 438.29 (15) Å3 |
Triclinic, P1 | Z = 1 |
a = 6.4649 (13) Å | Mo Kα radiation |
b = 7.2666 (15) Å | µ = 4.16 mm−1 |
c = 9.6951 (19) Å | T = 298 K |
α = 85.27 (3)° | 0.28 × 0.26 × 0.22 mm |
β = 77.31 (3)° |
Rigaku R-AXIS RAPID IP diffractometer | 2004 independent reflections |
Absorption correction: multi-scan ABSCOR (Higashi, 1995) | 1763 reflections with I > 2σ(I) |
Tmin = 0.389, Tmax = 0.461 | Rint = 0.029 |
4339 measured reflections |
R[F2 > 2σ(F2)] = 0.027 | 0 restraints |
wR(F2) = 0.066 | H atoms treated by a mixture of independent and constrained refinement |
S = 1.04 | Δρmax = 0.87 e Å−3 |
2004 reflections | Δρmin = −0.60 e Å−3 |
146 parameters |
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. The highest residual peak, 0.871 e A3, is close to O (1) (with the distance of ca 0.967 A), to C(1) with the distance of ca 1.296 A, but featureless. The deepest hole is -0.604 e A3. |
x | y | z | Uiso*/Ueq | ||
Zn1 | 0.0000 | 0.0000 | 0.0000 | 0.02280 (11) | |
Zn2 | 0.43151 (4) | −0.21372 (4) | 0.32805 (3) | 0.02389 (10) | |
C1 | −0.1926 (4) | 0.3065 (4) | 0.4125 (2) | 0.0263 (5) | |
C2 | −0.0112 (4) | 0.3838 (3) | 0.3087 (2) | 0.0220 (5) | |
H2A | 0.1033 | 0.3924 | 0.3569 | 0.026* | |
H2B | −0.0624 | 0.5087 | 0.2756 | 0.026* | |
C3 | 0.0768 (3) | 0.2625 (3) | 0.1818 (2) | 0.0179 (4) | |
C4 | 0.2481 (4) | 0.3533 (3) | 0.0755 (2) | 0.0224 (5) | |
H4A | 0.1908 | 0.4827 | 0.0582 | 0.027* | |
H4B | 0.3698 | 0.3527 | 0.1189 | 0.027* | |
C5 | 0.3282 (4) | 0.2647 (3) | −0.0660 (2) | 0.0213 (5) | |
C6 | 0.1701 (4) | 0.0658 (3) | 0.2287 (2) | 0.0198 (4) | |
O1 | −0.2934 (4) | 0.1977 (5) | 0.3701 (2) | 0.0669 (9) | |
O2 | −0.2314 (3) | 0.3509 (3) | 0.53876 (18) | 0.0344 (5) | |
O3 | 0.2747 (3) | 0.1149 (3) | −0.09162 (18) | 0.0300 (4) | |
O4 | 0.4538 (3) | 0.3523 (3) | −0.15702 (18) | 0.0300 (4) | |
O5 | 0.2952 (3) | 0.0518 (3) | 0.31332 (18) | 0.0260 (4) | |
O6 | 0.1257 (3) | −0.0737 (2) | 0.17968 (19) | 0.0324 (4) | |
O7 | −0.0943 (3) | 0.2466 (2) | 0.11071 (17) | 0.0210 (3) | |
O8 | 0.6828 (3) | −0.1961 (3) | 0.41525 (19) | 0.0334 (4) | |
H2 | 0.7285 | −0.0927 | 0.3885 | 0.050* | |
H1 | 0.6486 | −0.2004 | 0.5051 | 0.050* | |
H1A | −0.191 (6) | 0.237 (5) | 0.173 (4) | 0.049 (11)* |
U11 | U22 | U33 | U12 | U13 | U23 | |
Zn1 | 0.0297 (2) | 0.0247 (2) | 0.01762 (18) | −0.01201 (16) | −0.00723 (15) | −0.00034 (15) |
Zn2 | 0.02577 (16) | 0.02446 (16) | 0.01887 (15) | −0.00433 (11) | 0.00168 (10) | −0.00202 (11) |
C1 | 0.0259 (12) | 0.0329 (13) | 0.0189 (10) | −0.0080 (10) | 0.0010 (9) | −0.0016 (10) |
C2 | 0.0240 (11) | 0.0246 (12) | 0.0160 (10) | −0.0050 (9) | 0.0003 (8) | −0.0023 (9) |
C3 | 0.0198 (10) | 0.0219 (11) | 0.0130 (9) | −0.0066 (9) | −0.0025 (8) | −0.0018 (8) |
C4 | 0.0256 (12) | 0.0246 (12) | 0.0168 (10) | −0.0103 (9) | 0.0010 (9) | −0.0011 (9) |
C5 | 0.0185 (11) | 0.0260 (12) | 0.0182 (10) | −0.0029 (9) | −0.0011 (8) | −0.0014 (9) |
C6 | 0.0210 (11) | 0.0242 (11) | 0.0140 (9) | −0.0064 (9) | −0.0011 (8) | −0.0010 (9) |
O1 | 0.0598 (15) | 0.119 (2) | 0.0318 (11) | −0.0641 (17) | 0.0145 (10) | −0.0292 (14) |
O2 | 0.0445 (11) | 0.0434 (11) | 0.0162 (8) | −0.0231 (9) | 0.0056 (7) | −0.0072 (8) |
O3 | 0.0324 (10) | 0.0317 (10) | 0.0256 (9) | −0.0144 (8) | 0.0045 (7) | −0.0106 (8) |
O4 | 0.0338 (10) | 0.0315 (10) | 0.0215 (8) | −0.0144 (8) | 0.0094 (7) | −0.0056 (7) |
O5 | 0.0269 (9) | 0.0278 (9) | 0.0254 (8) | −0.0009 (7) | −0.0118 (7) | −0.0031 (7) |
O6 | 0.0510 (12) | 0.0192 (9) | 0.0351 (10) | −0.0106 (8) | −0.0243 (9) | 0.0041 (7) |
O7 | 0.0204 (8) | 0.0277 (9) | 0.0157 (7) | −0.0045 (7) | −0.0047 (6) | −0.0013 (6) |
O8 | 0.0377 (11) | 0.0377 (11) | 0.0253 (9) | −0.0043 (8) | −0.0086 (8) | −0.0020 (8) |
Zn1—O3 | 2.0707 (18) | C3—O7 | 1.449 (3) |
Zn1—O3i | 2.0707 (18) | C3—C4 | 1.529 (3) |
Zn1—O6i | 2.0768 (18) | C3—C6 | 1.535 (3) |
Zn1—O6 | 2.0768 (18) | C4—C5 | 1.515 (3) |
Zn1—O7i | 2.1029 (18) | C4—H4A | 0.9700 |
Zn1—O7 | 2.1029 (18) | C4—H4B | 0.9700 |
Zn2—O2ii | 1.9475 (19) | C5—O3 | 1.252 (3) |
Zn2—O4iii | 1.9528 (18) | C5—O4 | 1.264 (3) |
Zn2—O5 | 1.9992 (19) | C6—O6 | 1.252 (3) |
Zn2—O8 | 2.0141 (19) | C6—O5 | 1.261 (3) |
C1—O1 | 1.245 (3) | O2—Zn2ii | 1.9475 (19) |
C1—O2 | 1.254 (3) | O4—Zn2iii | 1.9528 (18) |
C1—C2 | 1.516 (3) | O7—H1A | 0.78 (4) |
C2—C3 | 1.526 (3) | O8—H2 | 0.8500 |
C2—H2A | 0.9700 | O8—H1 | 0.8500 |
C2—H2B | 0.9700 | ||
O3—Zn1—O3i | 180.00 (9) | O7—C3—C2 | 109.47 (18) |
O3—Zn1—O6i | 91.13 (8) | O7—C3—C4 | 107.60 (17) |
O3i—Zn1—O6i | 88.87 (8) | C2—C3—C4 | 110.10 (18) |
O3—Zn1—O6 | 88.87 (8) | O7—C3—C6 | 108.42 (17) |
O3i—Zn1—O6 | 91.13 (8) | C2—C3—C6 | 110.98 (18) |
O6i—Zn1—O6 | 180.00 (11) | C4—C3—C6 | 110.19 (19) |
O3—Zn1—O7i | 94.73 (7) | C5—C4—C3 | 116.49 (18) |
O3i—Zn1—O7i | 85.27 (7) | C5—C4—H4A | 108.2 |
O6i—Zn1—O7i | 78.62 (7) | C3—C4—H4A | 108.2 |
O6—Zn1—O7i | 101.38 (7) | C5—C4—H4B | 108.2 |
O3—Zn1—O7 | 85.27 (7) | C3—C4—H4B | 108.2 |
O3i—Zn1—O7 | 94.73 (7) | H4A—C4—H4B | 107.3 |
O6i—Zn1—O7 | 101.38 (7) | O3—C5—O4 | 122.0 (2) |
O6—Zn1—O7 | 78.62 (7) | O3—C5—C4 | 122.6 (2) |
O7i—Zn1—O7 | 180.00 (8) | O4—C5—C4 | 115.4 (2) |
O2ii—Zn2—O4iii | 109.95 (8) | O6—C6—O5 | 122.3 (2) |
O2ii—Zn2—O5 | 108.17 (9) | O6—C6—C3 | 119.8 (2) |
O4iii—Zn2—O5 | 119.97 (8) | O5—C6—C3 | 117.8 (2) |
O2ii—Zn2—O8 | 108.62 (8) | C1—O2—Zn2ii | 116.04 (16) |
O4iii—Zn2—O8 | 106.38 (8) | C5—O3—Zn1 | 128.61 (16) |
O5—Zn2—O8 | 103.11 (8) | C5—O4—Zn2iii | 111.81 (15) |
O1—C1—O2 | 122.6 (2) | C6—O5—Zn2 | 108.96 (16) |
O1—C1—C2 | 118.9 (2) | C6—O6—Zn1 | 111.25 (16) |
O2—C1—C2 | 118.5 (2) | C3—O7—Zn1 | 106.24 (13) |
C1—C2—C3 | 112.11 (19) | C3—O7—H1A | 103 (3) |
C1—C2—H2A | 109.2 | Zn1—O7—H1A | 111 (3) |
C3—C2—H2A | 109.2 | Zn2—O8—H2 | 109.3 |
C1—C2—H2B | 109.2 | Zn2—O8—H1 | 111.9 |
C3—C2—H2B | 109.2 | H2—O8—H1 | 107.6 |
H2A—C2—H2B | 107.9 |
Symmetry codes: (i) −x, −y, −z; (ii) −x, −y, −z+1; (iii) −x+1, −y, −z. |
Experimental details
Crystal data | |
Chemical formula | [Zn3(C6H5O7)2(H2O)2] |
Mr | 610.34 |
Crystal system, space group | Triclinic, P1 |
Temperature (K) | 298 |
a, b, c (Å) | 6.4649 (13), 7.2666 (15), 9.6951 (19) |
α, β, γ (°) | 85.27 (3), 77.31 (3), 80.99 (3) |
V (Å3) | 438.29 (15) |
Z | 1 |
Radiation type | Mo Kα |
µ (mm−1) | 4.16 |
Crystal size (mm) | 0.28 × 0.26 × 0.22 |
Data collection | |
Diffractometer | Rigaku R-AXIS RAPID IP diffractometer |
Absorption correction | Multi-scan ABSCOR (Higashi, 1995) |
Tmin, Tmax | 0.389, 0.461 |
No. of measured, independent and observed [I > 2σ(I)] reflections | 4339, 2004, 1763 |
Rint | 0.029 |
(sin θ/λ)max (Å−1) | 0.649 |
Refinement | |
R[F2 > 2σ(F2)], wR(F2), S | 0.027, 0.066, 1.04 |
No. of reflections | 2004 |
No. of parameters | 146 |
H-atom treatment | H atoms treated by a mixture of independent and constrained refinement |
Δρmax, Δρmin (e Å−3) | 0.87, −0.60 |
Computer programs: RAPID-AUTO (Rigaku, 1998), SHELXS97 (Sheldrick, 2008), SHELXL97 (Sheldrick, 2008), SHELXTL-Plus (Sheldrick, 2008).
Zn1—O3 | 2.0707 (18) | Zn2—O4ii | 1.9528 (18) |
Zn1—O6 | 2.0768 (18) | Zn2—O5 | 1.9992 (19) |
Zn1—O7 | 2.1029 (18) | Zn2—O8 | 2.0141 (19) |
Zn2—O2i | 1.9475 (19) |
Symmetry codes: (i) −x, −y, −z+1; (ii) −x+1, −y, −z. |
Acknowledgements
This work was supported by the National Natural Science Foundation of China (20701005/20701006), the Analysis and Testing Foundation of Northeast Normal University and the Ph. D Station Foundation of Ministry of Education (20060200002).
References
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The design and synthesis of coordination polymers with extended frameworks has drawn great attention due to their potential applications in catalysis, ligand exchange and their physical properties (Yaghi et al., 1996; Bourne et al., 2001). The coordination chemistry of biologically relevant transition metal ions toward citric acid has been widely investigated (Liu et al., 2005; Xie et al., 2005.) In this work, a new zinc(II) coordination polymer with citric acid (1) has been synthesized. The structure of (1) is reported here, shown in Fig. 1.
In (1) a compact layered structure is evident. An isolated Zn(1) ion is situated on an inversion center and is linked with two symmetry-related citrate ligands. It is surrounded in a distorted octahedral coordination by six oxygen atoms from four carboxylate oxygen atoms and two hydroxyl oxygen atoms from the citrate ligands. The Zn(1)—O distance are in the range of 2.0707 (18) - 2.1029 (18) Å. The Zn(2) ion is coordinated by three oxygen atoms from three carboxylate ligands and an oxygen from a water molecule in a distorted tetrahedral coordination. The Zn(2)—O distances are in the range of 1.9475 (19) - 2.0141 (19) Å. The ZnO6 and ZnO4 units are linked into a layer structure extending parallel to the ac plane (Fig. 2).
Recently, another polymorph of a compound with this composition has been reported by Wu (2008). The main structural difference of (1) and the first polymorph is the coordination of the zinc cations. In the first polymorph solely ZnO6 units are present. However, by linking the structural units, a layered structure is likewise formed in this polymorph.