metal-organic compounds
Monoclinic polymorph of poly[[di-μ-aqua-triaquadi-μ-oxalato-barium(II)copper(II)] monohydrate]
aDepartment of Inorganic Chemistry, University of Yaounde I, POB 812 Yaounde, Cameroon, and bInstitut für Anorganische Chemie, RWTH Aachen University, D-52056 Aachen, Germany
*Correspondence e-mail: belombe2000@yahoo.fr
A monoclinic polymorph of the title compound, {[BaCu(C2O4)2(H2O)5]·H2O}n, is reported. The structure is best described as a coordination polymer where the CuII and BaII centers are coordinated by five and nine O atoms, respectively, in capped quadratic antiprismatic and tetragonal pyramidal geometries. The polymerization arises due to the presence of bridging mono- and bidentate oxalate ligands as well as bridging water molecules. The is consolidated by a three-dimensional network of hydrogen bonding.
Related literature
For related literature, see: Bélombé et al. (2003, 2006); Belombe, Nenwa, Bebga et al. (2007); Bélombé, Nenwa, Mbiangué et al. (2007); Bouayad et al. (1995); Nenwa (2004). For synthesis, see: Kirschner (1960).
Experimental
Crystal data
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Refinement
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Data collection: SMART (Bruker, 1998); cell SAINT (Bruker, 2000); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: DIAMOND (Brandenburg, 1999); software used to prepare material for publication: WinGX (Farrugia, 1999).
Supporting information
https://doi.org/10.1107/S1600536807064525/tk2219sup1.cif
contains datablocks I, global. DOI:Structure factors: contains datablock I. DOI: https://doi.org/10.1107/S1600536807064525/tk2219Isup2.hkl
Compound (I) was obtained by mixing Ba(NO3)2 (0.31 g, 1.2 mmol, Riedel-de Haën, pure) and K2[Cu(C2O4)2].2H2O (0.18 g, 0.51 mmol), freshly prepared according to the method of Kirschner (1960), in warm water (60 °C; 100 ml). A solid precipitated immediately. The mixture was stirred for about 1 h at the same temperature and left to stand undisturbed over three days at ambient temperature. The blue prismatic crystals that formed were isolated by filtration, dried in air and one of these was used in the X-ray diffraction analysis.
All water-bound H atoms were first located in a difference Fourier map and then refined with distance restraints of O–H = 0.83 (3) Å with all Uiso(H) freely refined. The highest peak and deepest hole in the final difference Fourier map are, respectively, 0.49 Å from atom H13B and 1.00 Å from Cu.
Bouayad et al. (1995) reported the structure of the title compound, (I), in the triclinic
P-1. Herein, a new polymorph of (I) is reported which crystallizes in the monoclinic C2/c. It was obtained unintentionally from aqueous solution during an on-going study of oxalate-based multifunctional materials (Bélombé et al., 2003, 2006; Belombe, Nenwa, Bebga et al., 2007; Bélombé, Nenwa, Mbiangué et al., 2007; Nenwa, 2004), and is formulated as {[Ba(H2O)4][Cu(C2O4)2(H2O)].H2O}n. The two polymorphs structurally differ with respect to their crystal systems as well as in their coordination modes around the metal centers and in the formation of their lattice networks in the bulk.The lattice network reported by Bouayad et al. (1995) was shown to be a coordination polymer where each oxalate ion acts as a bidentate ligand, coordinating the metal centers in three different modes: first with the "internal", then with the "external" O atoms linked, respectively to CuII and BaII centers (thus generating pentacyclic rings) and, finally, with one "internal" and one "external" oxalato-O atoms bound to a neighboring Ba atom (thus forming a tetracyclic ring). In that structure, each CuII ion is hexa-coordinated by six O atoms that define a highly distorted octahedral geometry. By contrast, in the monoclinic polymorph, the CuII atom is penta-coordinated in an approximately square pyramidal geometry defined by five O atoms, with the Cu site slightly displaced from the least-squares plane through the O1–O4 atoms towards the axial water-O10 atom (Fig. 1). Therein, the coordination sphere around each BaII center which assumes
nine, as opposed to eleven in the triclinic polymorph, is emphasized. In the monoclinic form, the Ba site is located approximately at the center of a capped tetragonal antiprism, reminiscent of the geometry around the K+site in the salt K[Cr(C2O4)2(H2O)2] (Bélombé et al., 2006). Selected geometric parameters for the monoclinic polymorph are listed in Table 1 and compare very well with the published data for the triclinic polymorph (Bouayad et al., 1995).Taken individually, the [Cu(C2O4)2(H2O)]2- complex anions are virtually the same but are connected differently in the triclinic and monoclinic polymorphs. In the monoclinic polymorph, these ions are interconnected into layers parallel to the (101) plane via O–H···O bridges which involve the uncoordinated water molecules (Fig. 2). The 3-D polymerization arises from the linkage of "external" oxalato-O atoms to neighboring Ba centers via mono- or bi-dentate coordination modes, and by single and double water bridges across the O10 and O15/O15i atoms, respectively (Table 2). The latter double bridge interconnects the next two neighboring Ba atoms, related by a center of inversion, with a Ba···Ba separation of 4.788 (2) Å.
In conclusion, the present study reveals that the
symmetry in both structural polymorphs is basically dictated by the differing spatial orientations of the common anionic complexes, [Cu(C2O4)2(H2O)]2-, and variable coordination modes of the BaII centers.For related literature, see: Bélombé et al. (2003, 2006); Belombe, Nenwa, Bebga et al. (2007); Bélombé, Nenwa, Mbiangué et al. (2007); Bouayad et al. (1995); Nenwa (2004). For synthesis, see: Kirschner (1960).
Data collection: SMART (Bruker, 1998); cell
SMART (Bruker, 1998); data reduction: SAINT (Bruker, 2000); program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: DIAMOND (Brandenburg, 1999); software used to prepare material for publication: WinGX (Farrugia, 1999).Fig. 1. A view of the molecular structure of (I), expanded to show the coordination geometry around the BaII center, showing atom-numbering scheme and 50% probability displacement ellipsoids. Symmetry codes: (i) -x, y, -z + 1/2; (ii) x, -y + 1, z + 1/2; (iii) x - 1/2, y - 1/2, z; (iv) x, -y + 1, z - 1/2; (v) x + 1/2, y + 1/2, z. | |
Fig. 2. A view of the crystal packing in (I) projected down the b axis. Hydrogen bonds are drawn as dashed lines and coordinate bonds to the Ba centers are omitted for clarity. |
[BaCu(C2O4)2(H2O)5]·H2O | F(000) = 1864 |
Mr = 485.02 | Dx = 2.500 Mg m−3 |
Monoclinic, C2/c | Mo Kα radiation, λ = 0.71073 Å |
Hall symbol: -C 2yc | Cell parameters from 3213 reflections |
a = 15.744 (2) Å | θ = 2.3–28.3° |
b = 10.7565 (15) Å | µ = 4.76 mm−1 |
c = 15.345 (2) Å | T = 293 K |
β = 97.331 (2)° | Prism, blue |
V = 2577.5 (6) Å3 | 0.28 × 0.14 × 0.10 mm |
Z = 8 |
Bruker APEX CCD area detector diffractometer | 3213 independent reflections |
Radiation source: fine-focus sealed tube | 3180 reflections with I > 2σ(I) |
Graphite monochromator | Rint = 0.022 |
ω & φ scans | θmax = 28.3°, θmin = 2.3° |
Absorption correction: multi-scan (SADABS; Bruker, 2001) | h = −20→20 |
Tmin = 0.462, Tmax = 0.631 | k = −14→14 |
17321 measured reflections | l = −20→20 |
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)] = 0.020 | Hydrogen site location: inferred from neighbouring sites |
wR(F2) = 0.050 | All H-atom parameters refined |
S = 1.32 | w = 1/[σ2(Fo2) + (0.0219P)2 + 2.8035P] where P = (Fo2 + 2Fc2)/3 |
3213 reflections | (Δ/σ)max < 0.001 |
228 parameters | Δρmax = 0.49 e Å−3 |
12 restraints | Δρmin = −1.00 e Å−3 |
[BaCu(C2O4)2(H2O)5]·H2O | V = 2577.5 (6) Å3 |
Mr = 485.02 | Z = 8 |
Monoclinic, C2/c | Mo Kα radiation |
a = 15.744 (2) Å | µ = 4.76 mm−1 |
b = 10.7565 (15) Å | T = 293 K |
c = 15.345 (2) Å | 0.28 × 0.14 × 0.10 mm |
β = 97.331 (2)° |
Bruker APEX CCD area detector diffractometer | 3213 independent reflections |
Absorption correction: multi-scan (SADABS; Bruker, 2001) | 3180 reflections with I > 2σ(I) |
Tmin = 0.462, Tmax = 0.631 | Rint = 0.022 |
17321 measured reflections |
R[F2 > 2σ(F2)] = 0.020 | 12 restraints |
wR(F2) = 0.050 | All H-atom parameters refined |
S = 1.32 | Δρmax = 0.49 e Å−3 |
3213 reflections | Δρmin = −1.00 e Å−3 |
228 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. |
x | y | z | Uiso*/Ueq | ||
Ba | 0.141583 (8) | 0.466998 (11) | 0.208698 (8) | 0.01861 (5) | |
Cu | 0.392694 (18) | 0.57358 (3) | 0.044543 (18) | 0.02206 (7) | |
O1 | 0.32532 (11) | 0.68548 (15) | −0.03636 (11) | 0.0259 (3) | |
O2 | 0.32797 (11) | 0.44372 (15) | −0.02082 (11) | 0.0246 (3) | |
O3 | 0.46519 (11) | 0.70211 (15) | 0.10073 (11) | 0.0253 (3) | |
O4 | 0.47712 (11) | 0.45898 (14) | 0.10183 (12) | 0.0265 (4) | |
O5 | 0.59239 (11) | 0.46396 (15) | 0.20210 (12) | 0.0269 (4) | |
O6 | 0.23179 (11) | 0.57822 (15) | 0.36098 (11) | 0.0266 (3) | |
O7 | 0.23098 (12) | 0.32494 (15) | 0.34220 (12) | 0.0297 (4) | |
O8 | 0.08384 (11) | 0.22003 (16) | 0.19560 (12) | 0.0286 (4) | |
C1 | 0.27787 (14) | 0.4853 (2) | −0.08588 (15) | 0.0191 (4) | |
C2 | 0.52919 (14) | 0.6586 (2) | 0.15113 (14) | 0.0201 (4) | |
C3 | 0.53447 (14) | 0.5145 (2) | 0.15330 (15) | 0.0195 (4) | |
C4 | 0.27694 (14) | 0.6281 (2) | −0.09552 (15) | 0.0201 (4) | |
O10 | 0.29911 (11) | 0.57403 (16) | 0.16050 (12) | 0.0251 (3) | |
O11 | 0.21699 (14) | 0.32422 (18) | 0.09118 (15) | 0.0383 (5) | |
O12 | 0.09995 (15) | 0.58277 (19) | 0.04541 (13) | 0.0363 (4) | |
O13 | 0.09098 (17) | 0.7070 (2) | 0.24223 (18) | 0.0485 (6) | |
O14 | −0.06779 (16) | 0.6935 (2) | 0.05515 (17) | 0.0482 (5) | |
O15 | 0.03947 (12) | 0.45626 (19) | 0.34874 (13) | 0.0290 (4) | |
H10A | 0.287 (2) | 0.648 (2) | 0.166 (2) | 0.041 (9)* | |
H10B | 0.332 (2) | 0.557 (3) | 0.2032 (19) | 0.042 (10)* | |
H11A | 0.257 (2) | 0.351 (4) | 0.069 (2) | 0.053 (11)* | |
H11B | 0.237 (2) | 0.254 (3) | 0.106 (3) | 0.061 (12)* | |
H12A | 0.129 (2) | 0.643 (3) | 0.040 (2) | 0.046 (10)* | |
H12B | 0.0539 (18) | 0.611 (4) | 0.043 (3) | 0.056 (12)* | |
H13A | 0.097 (4) | 0.779 (3) | 0.226 (4) | 0.104 (14)* | |
H13B | 0.078 (3) | 0.721 (5) | 0.291 (2) | 0.104 (14)* | |
H14A | −0.106 (2) | 0.697 (4) | 0.016 (2) | 0.069 (14)* | |
H14B | −0.047 (3) | 0.764 (3) | 0.061 (3) | 0.091 (17)* | |
H15A | 0.047 (2) | 0.386 (3) | 0.368 (2) | 0.051 (11)* | |
H15B | 0.059 (3) | 0.506 (4) | 0.381 (3) | 0.066 (14)* |
U11 | U22 | U33 | U12 | U13 | U23 | |
Ba | 0.01904 (8) | 0.01779 (7) | 0.01834 (8) | −0.00038 (4) | −0.00019 (5) | 0.00062 (4) |
Cu | 0.02429 (14) | 0.01650 (13) | 0.02248 (14) | −0.00159 (10) | −0.00821 (10) | −0.00040 (10) |
O1 | 0.0300 (8) | 0.0164 (7) | 0.0279 (8) | −0.0009 (6) | −0.0089 (7) | −0.0011 (6) |
O2 | 0.0303 (9) | 0.0172 (7) | 0.0234 (8) | −0.0024 (6) | −0.0086 (7) | 0.0024 (6) |
O3 | 0.0263 (8) | 0.0181 (7) | 0.0286 (8) | −0.0022 (6) | −0.0071 (6) | −0.0001 (6) |
O4 | 0.0285 (9) | 0.0182 (7) | 0.0294 (9) | 0.0000 (6) | −0.0090 (7) | −0.0023 (6) |
O5 | 0.0244 (8) | 0.0235 (8) | 0.0302 (9) | 0.0007 (6) | −0.0059 (7) | 0.0022 (6) |
O6 | 0.0294 (8) | 0.0197 (8) | 0.0275 (8) | 0.0049 (6) | −0.0090 (7) | 0.0004 (6) |
O7 | 0.0349 (9) | 0.0191 (8) | 0.0307 (9) | −0.0022 (7) | −0.0132 (7) | −0.0014 (7) |
O8 | 0.0256 (8) | 0.0252 (8) | 0.0328 (9) | −0.0071 (7) | −0.0053 (7) | −0.0035 (7) |
C1 | 0.0189 (9) | 0.0173 (9) | 0.0208 (10) | −0.0010 (7) | 0.0009 (8) | 0.0002 (8) |
C2 | 0.0215 (10) | 0.0193 (10) | 0.0194 (10) | −0.0025 (8) | 0.0023 (8) | −0.0002 (8) |
C3 | 0.0206 (10) | 0.0189 (10) | 0.0190 (10) | −0.0006 (8) | 0.0026 (8) | 0.0001 (8) |
C4 | 0.0204 (10) | 0.0162 (9) | 0.0228 (10) | 0.0003 (7) | −0.0003 (8) | 0.0008 (8) |
O10 | 0.0253 (8) | 0.0215 (8) | 0.0266 (8) | 0.0002 (7) | −0.0044 (7) | −0.0004 (7) |
O11 | 0.0501 (12) | 0.0192 (8) | 0.0503 (12) | −0.0010 (8) | 0.0250 (10) | −0.0001 (8) |
O12 | 0.0451 (12) | 0.0278 (10) | 0.0344 (10) | −0.0054 (9) | −0.0014 (9) | 0.0072 (8) |
O13 | 0.0605 (15) | 0.0242 (10) | 0.0625 (15) | 0.0077 (10) | 0.0139 (12) | 0.0060 (10) |
O14 | 0.0460 (13) | 0.0465 (13) | 0.0501 (14) | −0.0039 (11) | −0.0018 (11) | 0.0160 (11) |
O15 | 0.0263 (9) | 0.0353 (10) | 0.0245 (9) | −0.0004 (7) | −0.0005 (7) | 0.0006 (8) |
Ba—O11 | 2.751 (2) | O7—C4ii | 1.231 (3) |
Ba—O13 | 2.770 (2) | O8—C2iii | 1.222 (3) |
Ba—O7 | 2.7888 (17) | C1—O6iv | 1.228 (3) |
Ba—O12 | 2.800 (2) | C1—C4 | 1.542 (3) |
Ba—O8 | 2.8066 (17) | C2—O8v | 1.222 (3) |
Ba—O6 | 2.8393 (17) | C2—C3 | 1.552 (3) |
Ba—O15 | 2.846 (2) | C4—O7iv | 1.231 (3) |
Ba—O15i | 2.8765 (19) | O10—H10A | 0.82 (2) |
Ba—O10 | 2.9140 (18) | O10—H10B | 0.80 (2) |
Ba—Bai | 4.7880 (7) | O11—H11A | 0.80 (2) |
Cu—O3 | 1.9252 (16) | O11—H11B | 0.84 (3) |
Cu—O2 | 1.9326 (16) | O12—H12A | 0.80 (2) |
Cu—O4 | 1.9393 (17) | O12—H12B | 0.78 (2) |
Cu—O1 | 1.9440 (16) | O13—H13A | 0.82 (3) |
Cu—O10 | 2.451 (3) | O13—H13B | 0.81 (3) |
O1—C4 | 1.269 (3) | O14—H14A | 0.80 (3) |
O2—C1 | 1.272 (3) | O14—H14B | 0.83 (3) |
O3—C2 | 1.278 (3) | O15—Bai | 2.8765 (19) |
O4—C3 | 1.270 (3) | O15—H15A | 0.81 (2) |
O5—C3 | 1.230 (3) | O15—H15B | 0.76 (3) |
O6—C1ii | 1.228 (3) | ||
O11—Ba—O13 | 143.20 (7) | O3—Cu—O2 | 174.10 (8) |
O11—Ba—O7 | 87.48 (6) | O3—Cu—O4 | 85.44 (7) |
O13—Ba—O7 | 120.30 (7) | O2—Cu—O4 | 93.52 (7) |
O11—Ba—O12 | 74.52 (7) | O3—Cu—O1 | 94.90 (7) |
O13—Ba—O12 | 73.24 (7) | O2—Cu—O1 | 84.69 (7) |
O7—Ba—O12 | 160.00 (6) | O4—Cu—O1 | 165.84 (8) |
O11—Ba—O8 | 65.64 (6) | O4—Cu—O10 | 96.48 (7) |
O13—Ba—O8 | 142.89 (7) | C4—O1—Cu | 112.60 (14) |
O7—Ba—O8 | 70.27 (5) | C1—O2—Cu | 112.70 (14) |
O12—Ba—O8 | 108.68 (6) | C2—O3—Cu | 112.62 (14) |
O11—Ba—O6 | 124.22 (6) | C3—O4—Cu | 112.01 (14) |
O13—Ba—O6 | 65.15 (7) | C1ii—O6—Ba | 120.20 (14) |
O7—Ba—O6 | 58.25 (5) | C4ii—O7—Ba | 122.45 (14) |
O12—Ba—O6 | 125.77 (6) | C2iii—O8—Ba | 138.63 (15) |
O8—Ba—O6 | 125.53 (5) | O6iv—C1—O2 | 125.4 (2) |
O11—Ba—O15 | 143.62 (6) | O6iv—C1—C4 | 119.5 (2) |
O13—Ba—O15 | 72.18 (7) | O2—C1—C4 | 115.03 (19) |
O7—Ba—O15 | 72.77 (6) | O8v—C2—O3 | 125.8 (2) |
O12—Ba—O15 | 127.12 (6) | O8v—C2—C3 | 119.7 (2) |
O8—Ba—O15 | 78.85 (6) | O3—C2—C3 | 114.49 (18) |
O6—Ba—O15 | 70.55 (6) | O5—C3—O4 | 125.7 (2) |
O11—Ba—O15i | 105.69 (6) | O5—C3—C2 | 119.2 (2) |
O13—Ba—O15i | 78.29 (7) | O4—C3—C2 | 115.09 (19) |
O7—Ba—O15i | 126.20 (6) | O7iv—C4—O1 | 126.5 (2) |
O12—Ba—O15i | 68.53 (6) | O7iv—C4—C1 | 118.73 (19) |
O8—Ba—O15i | 68.95 (5) | O1—C4—C1 | 114.74 (19) |
O6—Ba—O15i | 129.88 (5) | Ba—O10—H10A | 98 (2) |
O15—Ba—O15i | 66.20 (6) | Ba—O10—H10B | 101 (3) |
O11—Ba—O10 | 66.53 (6) | H10A—O10—H10B | 105 (3) |
O13—Ba—O10 | 87.32 (6) | Ba—O11—H11A | 120 (3) |
O7—Ba—O10 | 92.11 (5) | Ba—O11—H11B | 120 (3) |
O12—Ba—O10 | 72.95 (6) | H11A—O11—H11B | 98 (4) |
O8—Ba—O10 | 129.36 (5) | Ba—O12—H12A | 113 (3) |
O6—Ba—O10 | 71.93 (5) | Ba—O12—H12B | 109 (3) |
O15—Ba—O10 | 142.08 (5) | H12A—O12—H12B | 103 (4) |
O15i—Ba—O10 | 141.29 (5) | Ba—O13—H13A | 141 (4) |
O11—Ba—Bai | 131.91 (5) | Ba—O13—H13B | 117 (4) |
O13—Ba—Bai | 69.58 (5) | H13A—O13—H13B | 99 (5) |
O7—Ba—Bai | 101.84 (4) | H14A—O14—H14B | 106 (5) |
O12—Ba—Bai | 96.74 (5) | Ba—O15—Bai | 113.60 (6) |
O8—Ba—Bai | 73.44 (4) | Ba—O15—H15A | 104 (3) |
O6—Ba—Bai | 99.61 (4) | Bai—O15—H15A | 104 (3) |
O15—Ba—Bai | 33.40 (4) | Ba—O15—H15B | 104 (4) |
O15i—Ba—Bai | 33.00 (4) | Bai—O15—H15B | 118 (4) |
O10—Ba—Bai | 156.72 (3) | H15A—O15—H15B | 113 (4) |
Symmetry codes: (i) −x, y, −z+1/2; (ii) x, −y+1, z+1/2; (iii) x−1/2, y−1/2, z; (iv) x, −y+1, z−1/2; (v) x+1/2, y+1/2, z. |
D—H···A | D—H | H···A | D···A | D—H···A |
O10—H10A···O7vi | 0.82 (2) | 1.93 (2) | 2.740 (2) | 168 (3) |
O10—H10B···O5vii | 0.80 (2) | 2.02 (3) | 2.801 (2) | 163 (4) |
O10—H10B···O8vi | 0.80 (2) | 2.59 (3) | 3.114 (2) | 125 (3) |
O11—H11A···O2 | 0.80 (2) | 2.13 (3) | 2.903 (3) | 161 (4) |
O11—H11B···O6viii | 0.84 (3) | 2.00 (3) | 2.835 (3) | 172 (4) |
O11—H11B···O2ix | 0.84 (3) | 2.63 (4) | 3.127 (3) | 119 (3) |
O12—H12A···O1x | 0.80 (2) | 1.98 (3) | 2.768 (3) | 165 (4) |
O13—H13A···O5xi | 0.82 (3) | 2.02 (3) | 2.832 (3) | 168 (6) |
O13—H13B···O14i | 0.81 (3) | 2.41 (3) | 3.180 (4) | 159 (6) |
O14—H14A···O11xii | 0.80 (3) | 2.25 (3) | 3.041 (3) | 171 (5) |
O14—H14B···O4xi | 0.83 (3) | 2.21 (3) | 3.007 (3) | 163 (5) |
O15—H15A···O3viii | 0.81 (2) | 2.05 (3) | 2.845 (3) | 165 (4) |
O12—H12B···O14 | 0.78 (2) | 2.14 (3) | 2.918 (3) | 173 (4) |
O15—H15B···O14i | 0.76 (3) | 2.24 (3) | 2.952 (3) | 156 (5) |
Symmetry codes: (i) −x, y, −z+1/2; (vi) −x+1/2, y+1/2, −z+1/2; (vii) −x+1, y, −z+1/2; (viii) −x+1/2, y−1/2, −z+1/2; (ix) −x+1/2, −y+1/2, −z; (x) −x+1/2, −y+3/2, −z; (xi) x−1/2, y+1/2, z; (xii) −x, −y+1, −z. |
Experimental details
Crystal data | |
Chemical formula | [BaCu(C2O4)2(H2O)5]·H2O |
Mr | 485.02 |
Crystal system, space group | Monoclinic, C2/c |
Temperature (K) | 293 |
a, b, c (Å) | 15.744 (2), 10.7565 (15), 15.345 (2) |
β (°) | 97.331 (2) |
V (Å3) | 2577.5 (6) |
Z | 8 |
Radiation type | Mo Kα |
µ (mm−1) | 4.76 |
Crystal size (mm) | 0.28 × 0.14 × 0.10 |
Data collection | |
Diffractometer | Bruker APEX CCD area detector |
Absorption correction | Multi-scan (SADABS; Bruker, 2001) |
Tmin, Tmax | 0.462, 0.631 |
No. of measured, independent and observed [I > 2σ(I)] reflections | 17321, 3213, 3180 |
Rint | 0.022 |
(sin θ/λ)max (Å−1) | 0.667 |
Refinement | |
R[F2 > 2σ(F2)], wR(F2), S | 0.020, 0.050, 1.32 |
No. of reflections | 3213 |
No. of parameters | 228 |
No. of restraints | 12 |
H-atom treatment | All H-atom parameters refined |
Δρmax, Δρmin (e Å−3) | 0.49, −1.00 |
Computer programs: SMART (Bruker, 1998), SAINT (Bruker, 2000), SHELXS97 (Sheldrick, 1997), SHELXL97 (Sheldrick, 1997), DIAMOND (Brandenburg, 1999), WinGX (Farrugia, 1999).
Ba—O11 | 2.751 (2) | Ba—O15i | 2.8765 (19) |
Ba—O13 | 2.770 (2) | Ba—O10 | 2.9140 (18) |
Ba—O7 | 2.7888 (17) | Cu—O3 | 1.9252 (16) |
Ba—O12 | 2.800 (2) | Cu—O2 | 1.9326 (16) |
Ba—O8 | 2.8066 (17) | Cu—O4 | 1.9393 (17) |
Ba—O6 | 2.8393 (17) | Cu—O1 | 1.9440 (16) |
Ba—O15 | 2.846 (2) | Cu—O10 | 2.451 (3) |
O3—Cu—O2 | 174.10 (8) | O2—Cu—O1 | 84.69 (7) |
O3—Cu—O4 | 85.44 (7) | O4—Cu—O1 | 165.84 (8) |
O2—Cu—O4 | 93.52 (7) | O4—Cu—O10 | 96.48 (7) |
O3—Cu—O1 | 94.90 (7) |
Symmetry code: (i) −x, y, −z+1/2. |
D—H···A | D—H | H···A | D···A | D—H···A |
O10—H10A···O7ii | 0.82 (2) | 1.93 (2) | 2.740 (2) | 168 (3) |
O10—H10B···O5iii | 0.80 (2) | 2.02 (3) | 2.801 (2) | 163 (4) |
O10—H10B···O8ii | 0.80 (2) | 2.59 (3) | 3.114 (2) | 125 (3) |
O11—H11A···O2 | 0.80 (2) | 2.13 (3) | 2.903 (3) | 161 (4) |
O11—H11B···O6iv | 0.84 (3) | 2.00 (3) | 2.835 (3) | 172 (4) |
O11—H11B···O2v | 0.84 (3) | 2.63 (4) | 3.127 (3) | 119 (3) |
O12—H12A···O1vi | 0.80 (2) | 1.98 (3) | 2.768 (3) | 165 (4) |
O13—H13A···O5vii | 0.82 (3) | 2.02 (3) | 2.832 (3) | 168 (6) |
O13—H13B···O14i | 0.81 (3) | 2.41 (3) | 3.180 (4) | 159 (6) |
O14—H14A···O11viii | 0.80 (3) | 2.25 (3) | 3.041 (3) | 171 (5) |
O14—H14B···O4vii | 0.83 (3) | 2.21 (3) | 3.007 (3) | 163 (5) |
O15—H15A···O3iv | 0.81 (2) | 2.05 (3) | 2.845 (3) | 165 (4) |
O12—H12B···O14 | 0.78 (2) | 2.14 (3) | 2.918 (3) | 173 (4) |
O15—H15B···O14i | 0.76 (3) | 2.24 (3) | 2.952 (3) | 156 (5) |
Symmetry codes: (i) −x, y, −z+1/2; (ii) −x+1/2, y+1/2, −z+1/2; (iii) −x+1, y, −z+1/2; (iv) −x+1/2, y−1/2, −z+1/2; (v) −x+1/2, −y+1/2, −z; (vi) −x+1/2, −y+3/2, −z; (vii) x−1/2, y+1/2, z; (viii) −x, −y+1, −z. |
Acknowledgements
The authors are grateful to Klaus Kruse (RWTH Aachen) for technical support during the X-ray experiments.
References
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This is an open-access article distributed under the terms of the Creative Commons Attribution (CC-BY) Licence, which permits unrestricted use, distribution, and reproduction in any medium, provided the original authors and source are cited.
Bouayad et al. (1995) reported the structure of the title compound, (I), in the triclinic space group P-1. Herein, a new polymorph of (I) is reported which crystallizes in the monoclinic space group C2/c. It was obtained unintentionally from aqueous solution during an on-going study of oxalate-based multifunctional materials (Bélombé et al., 2003, 2006; Belombe, Nenwa, Bebga et al., 2007; Bélombé, Nenwa, Mbiangué et al., 2007; Nenwa, 2004), and is formulated as {[Ba(H2O)4][Cu(C2O4)2(H2O)].H2O}n. The two polymorphs structurally differ with respect to their crystal systems as well as in their coordination modes around the metal centers and in the formation of their lattice networks in the bulk.
The lattice network reported by Bouayad et al. (1995) was shown to be a coordination polymer where each oxalate ion acts as a bidentate ligand, coordinating the metal centers in three different modes: first with the "internal", then with the "external" O atoms linked, respectively to CuII and BaII centers (thus generating pentacyclic rings) and, finally, with one "internal" and one "external" oxalato-O atoms bound to a neighboring Ba atom (thus forming a tetracyclic ring). In that structure, each CuII ion is hexa-coordinated by six O atoms that define a highly distorted octahedral geometry. By contrast, in the monoclinic polymorph, the CuII atom is penta-coordinated in an approximately square pyramidal geometry defined by five O atoms, with the Cu site slightly displaced from the least-squares plane through the O1–O4 atoms towards the axial water-O10 atom (Fig. 1). Therein, the coordination sphere around each BaII center which assumes coordination number nine, as opposed to coordination number eleven in the triclinic polymorph, is emphasized. In the monoclinic form, the Ba site is located approximately at the center of a capped tetragonal antiprism, reminiscent of the geometry around the K+site in the salt K[Cr(C2O4)2(H2O)2] (Bélombé et al., 2006). Selected geometric parameters for the monoclinic polymorph are listed in Table 1 and compare very well with the published data for the triclinic polymorph (Bouayad et al., 1995).
Taken individually, the [Cu(C2O4)2(H2O)]2- complex anions are virtually the same but are connected differently in the triclinic and monoclinic polymorphs. In the monoclinic polymorph, these ions are interconnected into layers parallel to the (101) plane via O–H···O bridges which involve the uncoordinated water molecules (Fig. 2). The 3-D polymerization arises from the linkage of "external" oxalato-O atoms to neighboring Ba centers via mono- or bi-dentate coordination modes, and by single and double water bridges across the O10 and O15/O15i atoms, respectively (Table 2). The latter double bridge interconnects the next two neighboring Ba atoms, related by a center of inversion, with a Ba···Ba separation of 4.788 (2) Å.
In conclusion, the present study reveals that the unit cell symmetry in both structural polymorphs is basically dictated by the differing spatial orientations of the common anionic complexes, [Cu(C2O4)2(H2O)]2-, and variable coordination modes of the BaII centers.