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We present the first example of a compound containing Ba2+, C2O42-, water and some additional halide or pseudo-halide anions, viz. hexa-[mu]2-aqua-[mu]6-oxalato-dibarium(II) diiso­thio­cyanate, {[Ba2(C2O4)(H2O)6](NCS)2}n. The structure consists of positively charged planar covalent layers of Ba2+ cations, oxalate anions and water mol­ecules. The first coordination sphere of the Ba2+ cation contains six water mol­ecules and four O atoms from two planar oxalate anions. The oxalate anion lies on an inversion centre and is coordinated to six Ba2+ cations, each donor O atom being bonded to two cations. Pairs of water mol­ecules are coordinated by two Ba2+ cations. The layers are interspersed with non-coordinated NCS- anions.

Supporting information

cif

Crystallographic Information File (CIF) https://doi.org/10.1107/S0108270104010339/tr1090sup1.cif
Contains datablocks I, global

hkl

Structure factor file (CIF format) https://doi.org/10.1107/S0108270104010339/tr1090Isup2.hkl
Contains datablock I

CCDC reference: 245870

Comment top

By varying the experimental conditions, different barium oxalate salts can be obtained. The structures of [Ba(C2O4)(H2C2O4)(H2O)2] (Chaix-Pluchery et al., 1989), [Ba(C2O4)(H2C2O4)] (Mutin et al., 1979), [Ba2(C2O4)2(H2O)] (Mutin et al., 1981), [Ba(C2O4)(H2O)2] (Christensen et al., 1995), [Ba(C2O4)(H2O)] (Mutin et al., 1974; Huang & Mak, 1990), [Ba2(C2O4)2(H2O)7] (Neder et al., 1997) and [Ba2(C2O4)2(H2C2O4)(H2O)2] (Mutin & Dusausoy, 1981) have been determined by single-crystal and powder diffraction. In addition, various complexes containing transition metal cations, Ba2+ and oxalate are known. However, there are no structurally characterized compounds containing Ba2+, C2O42−, water and anions such as halide, pseudo-halide, chalcogenide, etc. In this article, we present the first example of such a compound, [Ba2(C2O4)(H2O)6](NCS)2, (I) (Fig. 1). \sch

The connectivity and dimensionality of barium oxalate structures have been analysed with the program package TOPOS using algorithms based on Voronoi-Dirichlet partition (Blatov et al., 2000), without assumption of any atomic radii. We have found that the structure of (I) is layered, in contrast with all previously known barium oxalates which have a three-dimensional polymeric structure, with the sole exception of [Ba2(C2O4)2(H2O)7] (Neder et al., 1997), which is also layered.

In the structure of (I), positively charged planar covalent layers of Ba2+ cations, oxalate anions and water molecules are interspersed with NCS anions (Fig. 2). Ten O atoms are coordinated to a Ba2+ cation, four of them belonging to oxalates and six to water molecules. The oxalate anion sits on a centre of inversion and is planar, with each O atom being bonded to two Ba2+ cations. Each water molecule is coordinated to two Ba2+ cations. Therefore, the structure of the layer can be described as [Ba(C2O4)3/6(H2O)6/2]n+ or [Ba26,η4-C2O4)(µ2-H2O)6]2+, or A2K42M62 (Porai-Koshits & Serezhkin, 1994).

Both the oxalate anion and Ba2+ cation centres form their own distorted triangular nets. Such motifs are typical for oxalates, according to Naumov et al. (1996). The topology of the layer is different from that found in [Ba2(C2O4)2(H2O)7], where Ba2+ forms regular hexagonal nets and the oxalate anion centres form distorted rectangular nets.

Weak hydrogen bonds between water molecules and the N atoms of the isothiocyanate anions join the layers together in (I). The O(water)···N distances are in the range 2.927 (12)–3.08 (2) Å. There is also a weak O(water)···S(CN) interaction, with an S···H distance of 2.51 (11) Å, between the isothiocyanate anion and one of the µ2-H2O molecules.

Experimental top

Compound (I) was obtained during investigation of the Ba(NCS)2—UO2(C2O4)-H2O system. Solid UO2(C2O4) was added to a hot aqueous solution of barium isothiocyanate with the molar ratio 1.5:1, giving a clear orange solution. After slow evaporation at room temperature, orange lath-shaped crystals precipitated which were identified as Ba3UO2(C2O4)2(NCS)2·8H2O (Markov & Sergeeva, 1961). These were filtered off and the solution was left for some time, resulting in a light-yellow crystalline precipitate, which appeared as a mixture of a fine yellow crystalline powder and colourless opaque plate-shaped crystals of (I).

Refinement top

After being located from a difference electron-density map, the positions of the water H atoms were refined with the O—H and H···H distances restrained to 0.82(s.u.?) and 1.36(s.u.?)Å, respectively, to give reasonable H—O—H angles, and with a Uiso value of 0.05 Å2.

Computing details top

Data collection: CAD-4 Software (Enraf-Nonius, 1988); cell refinement: CAD-4 Software; data reduction: CAD-4 Software; program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: TOPOS4.0 (Blatov et al., 2000); software used to prepare material for publication: local programs.

Figures top
[Figure 1] Fig. 1. The coordination spheres of the Ba2+ and oxalate ions in (I). Displacement ellipsoids are drawn at the 50% probability level. [Symmetry codes: (i) −x, 1 − y, 1 − z; (ii) x, 1 + y, z; (iii) 1 − x, 1 − y, 1 − z; (iv) −x, 2 − y, 1 − z; (v) 1 − x, −y, 1 − z; (vi) x, y − 1, z; (vii) 1 + x, y − 1, z.]
[Figure 2] Fig. 2. The crystal packing in (I). Short interlayer N···H and S···H contacts are shown with dashed lines.
hexa-µ2-aqua-µ6oxalato-dibarium(II) diisothiocyanate diisothiocyanate top
Crystal data top
[Ba2(C2O4)(H2O)6](NCS)2Z = 1
Mr = 586.96F(000) = 274
Triclinic, P1Dx = 2.421 Mg m3
Hall symbol: -P 1Mo Kα radiation, λ = 0.71073 Å
a = 6.8990 (9) ÅCell parameters from 24 reflections
b = 6.9441 (6) Åθ = 9–15°
c = 9.6383 (10) ŵ = 5.16 mm1
α = 85.517 (8)°T = 293 K
β = 71.498 (9)°Plate, colourless
γ = 67.037 (8)°0.11 × 0.11 × 0.06 mm
V = 402.63 (8) Å3
Data collection top
Enraf-Nonius CAD-4
diffractometer
1291 reflections with I > 2σ(I)
Radiation source: fine-focus sealed tubeRint = 0.025
Graphite monochromatorθmax = 25.0°, θmin = 2.2°
ω/2θ scansh = 78
Absorption correction: integration
(SHELX76; Sheldrick, 1986)
k = 88
Tmin = 0.428, Tmax = 0.819l = 011
1539 measured reflections3 standard reflections every 60 min
1411 independent reflections intensity decay: none
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)] = 0.040Hydrogen site location: inferred from neighbouring sites
wR(F2) = 0.157Only H-atom coordinates refined
S = 1.19 w = 1/[σ2(Fo2) + (0.0979P)2 + 5.3664P]
where P = (Fo2 + 2Fc2)/3
1411 reflections(Δ/σ)max < 0.001
109 parametersΔρmax = 1.70 e Å3
9 restraintsΔρmin = 1.81 e Å3
Crystal data top
[Ba2(C2O4)(H2O)6](NCS)2γ = 67.037 (8)°
Mr = 586.96V = 402.63 (8) Å3
Triclinic, P1Z = 1
a = 6.8990 (9) ÅMo Kα radiation
b = 6.9441 (6) ŵ = 5.16 mm1
c = 9.6383 (10) ÅT = 293 K
α = 85.517 (8)°0.11 × 0.11 × 0.06 mm
β = 71.498 (9)°
Data collection top
Enraf-Nonius CAD-4
diffractometer
1291 reflections with I > 2σ(I)
Absorption correction: integration
(SHELX76; Sheldrick, 1986)
Rint = 0.025
Tmin = 0.428, Tmax = 0.8193 standard reflections every 60 min
1539 measured reflections intensity decay: none
1411 independent reflections
Refinement top
R[F2 > 2σ(F2)] = 0.0409 restraints
wR(F2) = 0.157Only H-atom coordinates refined
S = 1.19Δρmax = 1.70 e Å3
1411 reflectionsΔρmin = 1.81 e Å3
109 parameters
Special details top

Experimental. none

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
Ba10.19564 (9)0.69341 (8)0.49723 (7)0.0203 (3)
C10.3930 (18)0.1007 (19)0.5118 (12)0.025 (2)
O10.4107 (13)0.2747 (12)0.5167 (9)0.0264 (17)
O20.2211 (12)0.0772 (12)0.5164 (9)0.0271 (17)
O30.3841 (16)0.5406 (16)0.7351 (10)0.037 (2)
H310.38 (3)0.640 (15)0.776 (14)0.050*
H320.38 (3)0.445 (16)0.789 (12)0.050*
O40.1388 (18)0.9715 (17)0.2599 (10)0.044 (2)
H410.06 (2)0.97 (3)0.213 (13)0.050*
H420.23 (2)1.02 (3)0.211 (13)0.050*
O50.1047 (14)0.4702 (13)0.3054 (10)0.0303 (18)
H510.218 (16)0.364 (15)0.282 (13)0.050*
H520.07 (2)0.52 (2)0.232 (9)0.050*
N10.478 (2)0.1252 (18)0.8393 (14)0.043 (3)
C20.327 (2)0.0227 (18)0.8799 (14)0.029 (3)
S10.1100 (6)0.2401 (6)0.9390 (4)0.0444 (9)
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
Ba10.0137 (4)0.0126 (4)0.0361 (5)0.0059 (3)0.0086 (3)0.0003 (3)
C10.018 (5)0.032 (6)0.028 (6)0.019 (5)0.003 (4)0.009 (5)
O10.028 (4)0.025 (4)0.036 (4)0.017 (3)0.014 (4)0.005 (3)
O20.014 (4)0.023 (4)0.049 (5)0.011 (3)0.011 (3)0.002 (4)
O30.042 (5)0.037 (5)0.037 (5)0.022 (4)0.007 (4)0.002 (4)
O40.048 (6)0.055 (6)0.037 (5)0.035 (5)0.009 (4)0.011 (5)
O50.024 (4)0.022 (4)0.041 (5)0.003 (3)0.009 (4)0.007 (4)
N10.034 (6)0.027 (6)0.062 (8)0.001 (5)0.016 (6)0.010 (5)
C20.026 (6)0.019 (6)0.039 (6)0.005 (5)0.008 (5)0.004 (5)
S10.0407 (19)0.0367 (19)0.0363 (18)0.0005 (15)0.0062 (15)0.0012 (14)
Geometric parameters (Å, º) top
Ba1—O12.723 (8)C1—O21.246 (13)
Ba1—O1i2.771 (8)N1—C21.122 (17)
Ba1—O2ii2.730 (8)C2—S11.637 (12)
Ba1—O2iii2.762 (8)O1—Ba1i2.771 (8)
Ba1—O32.916 (10)O2—Ba1ii2.730 (8)
Ba1—O3i2.972 (10)O2—Ba1vi2.762 (8)
Ba1—O42.899 (10)O3—Ba1i2.972 (10)
Ba1—O4iv3.074 (11)O3—H310.81 (16)
Ba1—O52.856 (8)O3—H320.81 (11)
Ba1—O5ii2.864 (9)O4—Ba1iv3.074 (11)
Ba1—Ba1i4.0215 (12)O4—H410.81 (15)
Ba1—Ba1iv4.0491 (12)O4—H420.83 (17)
Ba1—Ba1ii4.4777 (11)O5—Ba1ii2.864 (9)
C1—C1v1.55 (2)O5—H510.82 (11)
C1—O11.266 (14)O5—H520.83 (10)
O1—Ba1—O2ii131.4 (2)O3i—Ba1—Ba1i46.35 (19)
O1—Ba1—O2iii143.1 (2)O4iv—Ba1—Ba1i124.4 (2)
O2ii—Ba1—O2iii85.0 (2)O1—Ba1—Ba1iv172.56 (17)
O1—Ba1—O1i85.9 (2)O2ii—Ba1—Ba1iv42.82 (16)
O2ii—Ba1—O1i142.6 (2)O2iii—Ba1—Ba1iv42.20 (16)
O2iii—Ba1—O1i58.4 (2)O1i—Ba1—Ba1iv100.27 (17)
O1—Ba1—O571.0 (2)O5—Ba1—Ba1iv107.42 (17)
O2ii—Ba1—O571.9 (2)O5ii—Ba1—Ba1iv102.07 (16)
O2iii—Ba1—O5138.3 (3)O4—Ba1—Ba1iv49.2 (2)
O1i—Ba1—O5129.9 (2)O3—Ba1—Ba1iv119.48 (19)
O1—Ba1—O5ii70.5 (2)O3i—Ba1—Ba1iv126.29 (19)
O2ii—Ba1—O5ii71.5 (2)O4iv—Ba1—Ba1iv45.52 (18)
O2iii—Ba1—O5ii128.4 (2)Ba1i—Ba1—Ba1iv142.59 (3)
O1i—Ba1—O5ii136.4 (2)O1—Ba1—Ba1ii65.08 (16)
O5—Ba1—O5ii77.0 (3)O2ii—Ba1—Ba1ii66.32 (16)
O1—Ba1—O4135.3 (3)O2iii—Ba1—Ba1ii150.80 (16)
O2ii—Ba1—O460.5 (3)O1i—Ba1—Ba1ii150.74 (17)
O2iii—Ba1—O461.8 (3)O5—Ba1—Ba1ii38.54 (18)
O1i—Ba1—O492.4 (3)O5ii—Ba1—Ba1ii38.42 (17)
O5—Ba1—O476.5 (3)O4—Ba1—Ba1ii105.3 (2)
O5ii—Ba1—O4130.2 (3)O3—Ba1—Ba1ii104.22 (18)
O1—Ba1—O360.0 (3)O3i—Ba1—Ba1ii100.74 (18)
O2ii—Ba1—O3134.5 (3)O4iv—Ba1—Ba1ii100.27 (18)
O2iii—Ba1—O391.6 (3)Ba1i—Ba1—Ba1ii108.41 (2)
O1i—Ba1—O360.8 (2)Ba1iv—Ba1—Ba1ii108.95 (2)
O5—Ba1—O3129.3 (3)O2—C1—O1125.6 (11)
O5ii—Ba1—O375.6 (3)O2—C1—C1v116.9 (12)
O4—Ba1—O3150.4 (3)O1—C1—C1v117.4 (11)
O1—Ba1—O3i60.5 (3)C1—O1—Ba1142.2 (7)
O2ii—Ba1—O3i131.2 (3)C1—O1—Ba1i122.9 (7)
O2iii—Ba1—O3i102.5 (2)Ba1—O1—Ba1i94.1 (2)
O1i—Ba1—O3i58.8 (2)C1—O2—Ba1ii140.0 (8)
O5—Ba1—O3i71.2 (2)C1—O2—Ba1vi124.3 (7)
O5ii—Ba1—O3i127.8 (2)Ba1ii—O2—Ba1vi95.0 (2)
O4—Ba1—O3i80.6 (3)Ba1—O3—Ba1i86.1 (2)
O3—Ba1—O3i93.9 (2)Ba1—O3—H31109 (10)
O1—Ba1—O4iv129.4 (3)Ba1i—O3—H31116 (10)
O2ii—Ba1—O4iv59.8 (3)Ba1—O3—H32131 (10)
O2iii—Ba1—O4iv58.0 (2)Ba1i—O3—H3299 (10)
O1i—Ba1—O4iv101.3 (3)H31—O3—H32113 (13)
O5—Ba1—O4iv127.9 (3)Ba1—O4—Ba1iv85.3 (3)
O5ii—Ba1—O4iv70.5 (2)Ba1—O4—H41120 (10)
O4—Ba1—O4iv94.7 (3)Ba1iv—O4—H41101 (10)
O3—Ba1—O4iv80.1 (3)Ba1—O4—H42123 (10)
O3i—Ba1—O4iv159.0 (3)Ba1iv—O4—H42108 (10)
O1—Ba1—Ba1i43.42 (16)H41—O4—H42110 (15)
O2ii—Ba1—Ba1i174.36 (16)Ba1—O5—Ba1ii103.0 (3)
O2iii—Ba1—Ba1i100.41 (16)Ba1—O5—H51102 (10)
O1i—Ba1—Ba1i42.49 (16)Ba1ii—O5—H51100 (10)
O5—Ba1—Ba1i102.81 (17)Ba1—O5—H52122 (10)
O5ii—Ba1—Ba1i105.83 (17)Ba1ii—O5—H52116 (10)
O4—Ba1—Ba1i120.7 (2)H51—O5—H52110 (12)
O3—Ba1—Ba1i47.51 (19)N1—C2—S1179.2 (13)
Symmetry codes: (i) x+1, y+1, z+1; (ii) x, y+1, z+1; (iii) x, y+1, z; (iv) x, y+2, z+1; (v) x+1, y, z+1; (vi) x, y1, z.

Experimental details

Crystal data
Chemical formula[Ba2(C2O4)(H2O)6](NCS)2
Mr586.96
Crystal system, space groupTriclinic, P1
Temperature (K)293
a, b, c (Å)6.8990 (9), 6.9441 (6), 9.6383 (10)
α, β, γ (°)85.517 (8), 71.498 (9), 67.037 (8)
V3)402.63 (8)
Z1
Radiation typeMo Kα
µ (mm1)5.16
Crystal size (mm)0.11 × 0.11 × 0.06
Data collection
DiffractometerEnraf-Nonius CAD-4
diffractometer
Absorption correctionIntegration
(SHELX76; Sheldrick, 1986)
Tmin, Tmax0.428, 0.819
No. of measured, independent and
observed [I > 2σ(I)] reflections
1539, 1411, 1291
Rint0.025
(sin θ/λ)max1)0.594
Refinement
R[F2 > 2σ(F2)], wR(F2), S 0.040, 0.157, 1.19
No. of reflections1411
No. of parameters109
No. of restraints9
H-atom treatmentOnly H-atom coordinates refined
Δρmax, Δρmin (e Å3)1.70, 1.81

Computer programs: CAD-4 Software (Enraf-Nonius, 1988), CAD-4 Software, SHELXS97 (Sheldrick, 1997), SHELXL97 (Sheldrick, 1997), TOPOS4.0 (Blatov et al., 2000), local programs.

Selected bond lengths (Å) top
Ba1—O12.723 (8)Ba1—O52.856 (8)
Ba1—O1i2.771 (8)Ba1—O5ii2.864 (9)
Ba1—O2ii2.730 (8)C1—C1v1.55 (2)
Ba1—O2iii2.762 (8)C1—O11.266 (14)
Ba1—O32.916 (10)C1—O21.246 (13)
Ba1—O3i2.972 (10)N1—C21.122 (17)
Ba1—O42.899 (10)C2—S11.637 (12)
Ba1—O4iv3.074 (11)
Symmetry codes: (i) x+1, y+1, z+1; (ii) x, y+1, z+1; (iii) x, y+1, z; (iv) x, y+2, z+1; (v) x+1, y, z+1.
 

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