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The synthesis of BaC
2O
4·0.5H
2O and its thermal decomposition to α-BaC
2O
4 and β-BaC
2O
4 was investigated. BaC
2O
4·0.5H
2O is precipitated at room temperature from aqueous solutions of barium chloride and ammonium oxalate. The deuterated compound BaC
2O
4·0.5D
2O was made in analogy with D
2O as the solvent. The compounds were characterized by X-ray and neutron diffraction analysis. Single-crystal X-ray diffraction of BaC
2O
4·0.5H
2O measured at 120 K gave the triclinic cell
a = 8.692 (1),
b = 9.216 (1),
c = 6.146 (1) Å, α = 95.094 (3), β = 95.492 (3), γ = 64.500 (3)°, space group
P,
Z = 4. Two independent Ba atoms are each coordinated to nine O atoms at distances from 2.73 (1) to 2.99 (1) Å. One of the two oxalate ions deviates significantly from planarity. The water molecule does form weak hydrogen bonds.
In situ X-ray powder diffraction was used to study the thermal decomposition of BaC
2O
4·0.5H
2O and the formation of α-BaC
2O
4. The X-ray powder pattern of α-BaC
2O
4 measured at 473 K was indexed on a triclinic cell with
a = 5.137 (3),
b = 8.764 (6),
c = 9.006 (4) Å, α = 83.57 (4), β = 98.68 (5), γ = 99.53 (5)°, and the space group
P with
Z = 4.
Supporting information
CCDC reference: 195793
Data collection: SMART (Siemens, 1995); cell refinement: SAINT (Siemens, 1995); data reduction: SAINT (Siemens, 1995); program(s) used to solve structure: SIR97 (Altomare et al., 1997 ), KRYSTAL; program(s) used to refine structure: modified ORFLS(1962), KRYSTAL; molecular graphics: ORTEP-III (Burnett & Johnson, 1996), KRYSTAL; software used to prepare material for publication: KRYSTAL.
Crystal data top
C4H2Ba2O9 | Z = 2 |
Mr = 468.72 | F(000) = 420 |
Triclinic, P1 | Dx = 3.524 Mg m−3 |
Hall symbol: -P 1 | Mo Kα radiation, λ = 0.71073 Å |
a = 8.692 (1) Å | Cell parameters from 1438 reflections |
b = 9.216 (1) Å | θ = 2.5–30.5° |
c = 6.146 (1) Å | µ = 8.89 mm−1 |
α = 95.094 (3)° | T = 120 K |
β = 95.492 (3)° | Plate, colourless |
γ = 64.500 (3)° | 0.15 × 0.06 × 0.01 mm |
V = 441.7 (1) Å3 | |
Data collection top
Siemens SMART CCD diffractometer | 2584 independent reflections |
Radiation source: x-ray tube | 1339 reflections with I > 3σ(I) |
Graphite monochromator | Rint = 0.075 |
ω rotation scans with narrow frames | θmax = 30.5°, θmin = 2.5° |
Absorption correction: integration XPREP,1995 | h = −12→12 |
Tmin = 0.28, Tmax = 0.84 | k = −13→13 |
12950 measured reflections | l = −8→8 |
Refinement top
Refinement on F | 0 constraints |
Least-squares matrix: full | H-atom parameters constrained |
R[F2 > 2σ(F2)] = 0.050 | w = 1/{[σcs(F2) + 1.03F2]1/2- |F|}2 |
wR(F2) = 0.054 | (Δ/σ)max = 0.00013 |
S = 1.20 | Δρmax = 4.0 (5) e Å−3 |
1339 reflections | Δρmin = −3.8 (5) e Å−3 |
72 parameters | Extinction correction: Type 1 Lorentzian isotropic (Becker and Coppens, 1974) |
0 restraints | Extinction coefficient: 7 (1) |
Crystal data top
C4H2Ba2O9 | γ = 64.500 (3)° |
Mr = 468.72 | V = 441.7 (1) Å3 |
Triclinic, P1 | Z = 2 |
a = 8.692 (1) Å | Mo Kα radiation |
b = 9.216 (1) Å | µ = 8.89 mm−1 |
c = 6.146 (1) Å | T = 120 K |
α = 95.094 (3)° | 0.15 × 0.06 × 0.01 mm |
β = 95.492 (3)° | |
Data collection top
Siemens SMART CCD diffractometer | 2584 independent reflections |
Absorption correction: integration XPREP,1995 | 1339 reflections with I > 3σ(I) |
Tmin = 0.28, Tmax = 0.84 | Rint = 0.075 |
12950 measured reflections | |
Refinement top
R[F2 > 2σ(F2)] = 0.050 | 0 restraints |
wR(F2) = 0.054 | H-atom parameters constrained |
S = 1.20 | Δρmax = 4.0 (5) e Å−3 |
1339 reflections | Δρmin = −3.8 (5) e Å−3 |
72 parameters | |
Special details top
Refinement. Because of heavy Ba atoms and weak dataset anisotropic refinement of carbon and
oxygen was not possible. |
Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top | x | y | z | Uiso*/Ueq | Occ. (<1) |
Ba1 | 0.9558 (1) | 0.2093 (1) | 0.2782 (2) | 0.0088 (7) | |
Ba2 | 0.3635 (1) | 0.4185 (1) | 0.2133 (2) | 0.0080 (7) | |
C1 | 0.924 (2) | 0.677 (2) | 0.176 (3) | 0.011 (3)* | |
C2 | 0.820 (2) | 0.627 (2) | 0.325 (3) | 0.012 (3)* | |
O1 | 0.875 (1) | 0.686 (1) | −0.019 (2) | 0.016 (3)* | |
O2 | 1.047 (1) | 0.696 (1) | 0.267 (2) | 0.013 (2)* | |
O3 | 0.747 (1) | 0.540 (1) | 0.238 (2) | 0.009 (2)* | |
O4 | 0.819 (2) | 0.673 (1) | 0.524 (2) | 0.020 (3)* | |
C3 | 0.276 (2) | 0.820 (2) | 0.136 (2) | 0.005 (3)* | |
C4 | 0.287 (2) | 0.817 (2) | 0.385 (3) | 0.013 (3)* | |
O5 | 0.356 (1) | 0.689 (1) | 0.029 (2) | 0.010 (2)* | |
O6 | 0.185 (1) | 0.950 (1) | 0.050 (2) | 0.014 (2)* | |
O7 | 0.370 (1) | 0.685 (1) | 0.475 (2) | 0.010 (2)* | |
O8 | 0.199 (1) | 0.947 (1) | 0.486 (2) | 0.015 (2)* | |
O9 | 0.516 (2) | 0.070 (1) | 0.220 (2) | 0.023 (3)* | |
H1 | 0.648 | 0.024 | 0.302 | 0.03* | |
H2 | 0.413 | 0.101 | 0.306 | 0.04* | 0.5 |
H3 | 0.457 | 0.082 | 0.132 | 0.04* | 0.5 |
Atomic displacement parameters (Å2) top | U11 | U22 | U33 | U12 | U13 | U23 |
Ba1 | 0.0104 (6) | 0.0060 (6) | 0.0123 (6) | −0.0053 (5) | 0.0014 (5) | 0.0025 (4) |
Ba2 | 0.0080 (6) | 0.0070 (6) | 0.0116 (6) | −0.0053 (5) | 0.0011 (4) | 0.0020 (4) |
Geometric parameters (Å, º) top
Ba1—O6i | 2.735 (11) | Ba2v—O4 | 2.776 (12) |
Ba1—O8i | 2.752 (11) | C1—O1 | 1.231 (18) |
Ba1—O1ii | 2.754 (11) | C1—O2 | 1.239 (19) |
Ba1—O4iii | 2.763 (12) | C1—C2 | 1.57 (2) |
Ba1—O3 | 2.819 (10) | C2—O3 | 1.267 (18) |
Ba1—O2iii | 2.855 (10) | C2—O4 | 1.260 (18) |
Ba1—O6iv | 2.878 (11) | C3—O6 | 1.248 (17) |
Ba1—O8v | 2.896 (11) | C3—O5 | 1.265 (16) |
Ba1—O5iv | 2.989 (11) | C3—C4 | 1.53 (2) |
Ba2—O5iv | 2.736 (10) | C4—O8 | 1.258 (18) |
Ba2—O7v | 2.744 (11) | C4—O7 | 1.261 (18) |
Ba2—O1iv | 2.769 (12) | Ba2iv—O5 | 2.736 (10) |
Ba2—O4v | 2.776 (12) | Ba2—O5 | 2.806 (10) |
Ba2—O5 | 2.806 (10) | Ba1iv—O5 | 2.989 (11) |
Ba2—O7 | 2.830 (10) | Ba1viii—O6 | 2.735 (11) |
Ba2—O3iv | 2.852 (10) | O6—H1iv | 2.796 (11) |
Ba2—O2vi | 2.859 (11) | Ba1iv—O6 | 2.878 (11) |
Ba2—O9 | 2.905 (12) | Ba2v—O7 | 2.744 (11) |
C1—O1 | 1.231 (18) | Ba2—O7 | 2.830 (10) |
Ba1ii—O1 | 2.754 (11) | O8—H1v | 1.857 (11) |
Ba2iv—O1 | 2.769 (12) | Ba1viii—O8 | 2.752 (11) |
C1—O2 | 1.239 (19) | O8—O9v | 2.880 (17) |
Ba1iii—O2 | 2.855 (10) | Ba1v—O8 | 2.896 (11) |
Ba2vii—O2 | 2.859 (11) | O9—H1 | 1.123 (13) |
C2—O3 | 1.267 (18) | O9—H3 | 0.690 (13) |
Ba1—O3 | 2.819 (10) | O9—H2 | 1.000 (13) |
Ba2iv—O3 | 2.852 (10) | O9—H3ix | 2.445 (12) |
C2—O4 | 1.260 (18) | Ba2—O9 | 2.905 (12) |
O4—H2v | 2.429 (12) | O9—O9ix | 2.93 (2) |
Ba1iii—O4 | 2.763 (12) | | |
| | | |
O6i—Ba1—O8i | 58.4 (3) | O5—Ba2—O7 | 58.0 (3) |
O1ii—Ba1—O6i | 70.9 (3) | O3iv—Ba2—O5 | 62.9 (3) |
O4iii—Ba1—O6i | 98.0 (3) | O2vi—Ba2—O5 | 67.6 (3) |
O3—Ba1—O6i | 140.4 (3) | O5—Ba2—O9 | 147.0 (3) |
O2iii—Ba1—O6i | 131.0 (3) | O3iv—Ba2—O7 | 118.7 (3) |
O6i—Ba1—O6iv | 63.6 (4) | O2vi—Ba2—O7 | 62.0 (3) |
O6i—Ba1—O8v | 100.6 (3) | O7—Ba2—O9 | 138.7 (3) |
O5iv—Ba1—O6i | 101.9 (3) | O2vi—Ba2—O3iv | 82.2 (3) |
O1ii—Ba1—O8i | 107.1 (3) | O3iv—Ba2—O9 | 100.4 (3) |
O4iii—Ba1—O8i | 77.4 (3) | O2vi—Ba2—O9 | 141.9 (3) |
O3—Ba1—O8i | 154.2 (3) | O2vi—Ba2—O9 | 141.9 (3) |
O2iii—Ba1—O8i | 73.9 (3) | Ba1ii—O1—C1 | 115.4 (10) |
O6iv—Ba1—O8i | 100.0 (3) | Ba2iv—O1—C1 | 124.9 (10) |
O8i—Ba1—O8v | 68.4 (4) | Ba1iii—O2—C1 | 119.1 (9) |
O5iv—Ba1—O8i | 142.5 (3) | Ba2vii—O2—C1 | 112.6 (10) |
O1ii—Ba1—O4iii | 61.0 (3) | Ba1—O3—C2 | 112.0 (9) |
O1ii—Ba1—O3 | 74.6 (3) | Ba2iv—O3—C2 | 116.5 (9) |
O1ii—Ba1—O2iii | 117.4 (3) | Ba1iii—O4—C2 | 123.1 (10) |
O1ii—Ba1—O6iv | 100.2 (3) | Ba2v—O4—C2 | 116.4 (10) |
O1ii—Ba1—O8v | 171.4 (3) | O1—C1—O2 | 128.3 (15) |
O1ii—Ba1—O5iv | 93.3 (3) | C2—C1—O1 | 115.2 (14) |
O3—Ba1—O4iii | 81.6 (3) | C2—C1—O2 | 116.4 (13) |
O2iii—Ba1—O4iii | 58.4 (3) | O3—C2—O4 | 125.2 (14) |
O4iii—Ba1—O6iv | 158.3 (3) | C1—C2—O3 | 118.1 (13) |
O4iii—Ba1—O8v | 123.2 (3) | C1—C2—O4 | 116.7 (13) |
O4iii—Ba1—O5iv | 139.9 (3) | O5—C3—O6 | 123.9 (13) |
O2iii—Ba1—O3 | 82.5 (3) | C4—C3—O6 | 118.5 (13) |
O3—Ba1—O6iv | 105.0 (3) | C4—C3—O5 | 117.6 (13) |
O3—Ba1—O8v | 112.8 (3) | O7—C4—O8 | 124.1 (14) |
O3—Ba1—O5iv | 61.0 (3) | C3—C4—O8 | 116.2 (13) |
O2iii—Ba1—O6iv | 142.2 (3) | C3—C4—O7 | 119.4 (13) |
O2iii—Ba1—O8v | 69.1 (3) | Ba2iv—O5—C3 | 132.7 (9) |
O2iii—Ba1—O5iv | 124.1 (3) | Ba2—O5—C3 | 113.9 (8) |
O6iv—Ba1—O8v | 74.0 (3) | Ba1iv—O5—C3 | 85.8 (8) |
O5iv—Ba1—O6iv | 44.4 (3) | Ba1viii—O6—C3 | 122.2 (9) |
O5iv—Ba1—O8v | 86.8 (3) | Ba1iv—O6—C3 | 91.2 (8) |
O5iv—Ba2—O7v | 77.1 (3) | Ba2v—O7—C4 | 133.4 (10) |
O1iv—Ba2—O5iv | 110.8 (3) | Ba2—O7—C4 | 112.9 (9) |
O4v—Ba2—O5iv | 144.8 (3) | Ba1viii—O8—C4 | 122.6 (10) |
O5iv—Ba2—O5 | 73.5 (3) | Ba1v—O8—C4 | 91.5 (9) |
O5iv—Ba2—O7 | 105.3 (3) | H1—O9—H3 | 154.5 (16) |
O3iv—Ba2—O5iv | 71.0 (3) | H1—O9—H2 | 121.6 (11) |
O2vi—Ba2—O5iv | 139.7 (3) | H1—O9—H3ix | 105.9 (7) |
O5iv—Ba2—O9 | 74.1 (3) | O8v—O9—H1 | 19.3 (5) |
O1iv—Ba2—O7v | 137.2 (3) | Ba2—O9—H1 | 110.5 (8) |
O4v—Ba2—O7v | 88.1 (3) | O9ix—O9—H1 | 116.2 (9) |
O5—Ba2—O7v | 108.5 (3) | H2—O9—H3 | 83.0 (12) |
O7v—Ba2—O7 | 70.1 (3) | H3—O9—H3ix | 50.4 (8) |
O3iv—Ba2—O7v | 148.2 (3) | O8v—O9—H3 | 164.7 (13) |
O2vi—Ba2—O7v | 124.7 (3) | Ba2—O9—H3 | 79.2 (10) |
O7v—Ba2—O9 | 69.7 (3) | O9ix—O9—H3 | 39.9 (7) |
O1iv—Ba2—O4v | 60.7 (3) | H2—O9—H3ix | 121.1 (9) |
O1iv—Ba2—O5 | 114.1 (3) | O8v—O9—H2 | 109.4 (8) |
O1iv—Ba2—O7 | 138.6 (3) | Ba2—O9—H2 | 78.1 (7) |
O1iv—Ba2—O3iv | 58.4 (3) | O9ix—O9—H2 | 113.7 (11) |
O1iv—Ba2—O2vi | 77.2 (3) | O8v—O9—H3ix | 124.0 (5) |
O1iv—Ba2—O9 | 72.4 (3) | Ba2—O9—H3ix | 117.2 (4) |
O4v—Ba2—O5 | 141.7 (3) | O9ix—O9—H3ix | 10.4 (2) |
O4v—Ba2—O7 | 99.2 (3) | Ba2—O9—O8v | 94.2 (4) |
O3iv—Ba2—O4v | 118.0 (3) | O8v—O9—O9ix | 133.9 (7) |
O2vi—Ba2—O4v | 74.5 (3) | Ba2—O9—O9ix | 109.7 (6) |
O4v—Ba2—O9 | 70.8 (3) | | |
Symmetry codes: (i) x+1, y−1, z; (ii) −x+2, −y+1, −z; (iii) −x+2, −y+1, −z+1; (iv) −x+1, −y+1, −z; (v) −x+1, −y+1, −z+1; (vi) x−1, y, z; (vii) x+1, y, z; (viii) x−1, y+1, z; (ix) −x+1, −y, −z. |
Experimental details
Crystal data |
Chemical formula | C4H2Ba2O9 |
Mr | 468.72 |
Crystal system, space group | Triclinic, P1 |
Temperature (K) | 120 |
a, b, c (Å) | 8.692 (1), 9.216 (1), 6.146 (1) |
α, β, γ (°) | 95.094 (3), 95.492 (3), 64.500 (3) |
V (Å3) | 441.7 (1) |
Z | 2 |
Radiation type | Mo Kα |
µ (mm−1) | 8.89 |
Crystal size (mm) | 0.15 × 0.06 × 0.01 |
|
Data collection |
Diffractometer | Siemens SMART CCD diffractometer |
Absorption correction | Integration XPREP,1995 |
Tmin, Tmax | 0.28, 0.84 |
No. of measured, independent and observed [I > 3σ(I)] reflections | 12950, 2584, 1339 |
Rint | 0.075 |
(sin θ/λ)max (Å−1) | 0.714 |
|
Refinement |
R[F2 > 2σ(F2)], wR(F2), S | 0.050, 0.054, 1.20 |
No. of reflections | 1339 |
No. of parameters | 72 |
H-atom treatment | H-atom parameters constrained |
Δρmax, Δρmin (e Å−3) | 4.0 (5), −3.8 (5) |
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