Anhydrous barium strontium oxalate

In the title compound, (Ba_0.741Sr_0.259)C₂O₄ or C₂Ba_0.741O₄Sr_0.259, the asymmetric unit consists of one disordered barium/strontium ion lying on a crystallographic twofold rotation axis and half of a centrosymmetric oxalate ion (one C and two O atoms). The crystal structure can be described as double parallel zigzag chains runnning along the c axis and linked together by additional monodentate oxalate-metal bonding. The distance between two chains is b/2. Each metal ion has six O-atom neighbours and they are linked together via the different coordination modes of the oxalate groups, resulting in the formation of a three-dimensional network.

Key indicators

• Single-crystal X-ray study
• T = 296 K
• Mean [sigma](C-C) = 0.008 Å
• Disorder in main residue
• R factor = 0.026
• wR factor = 0.077
• Data-to-parameter ratio = 16.0

checkCIF/PLATON results

No syntax errors found



Datablock: I


Alert level C
PLAT040_ALERT_1_C No H-atoms in this Carbon Containing Compound ..          ?
PLAT041_ALERT_1_C Calc. and Rep. SumFormula Strings    Differ ....          ?
PLAT042_ALERT_1_C Calc. and Rep. MoietyFormula Strings Differ ....          ?
PLAT045_ALERT_1_C Calculated and Reported Z Differ by ............       0.25 Ratio
PLAT068_ALERT_1_C Reported F000 Differs from Calcd (or Missing)...          ?
PLAT077_ALERT_4_C Unitcell contains non-integer number of atoms ..          ?
PLAT094_ALERT_2_C Ratio of Maximum / Minimum Residual Density ....       2.70
PLAT153_ALERT_1_C The su's on the Cell Axes are Equal (x 100000) .        500 Ang.
PLAT301_ALERT_3_C Main Residue  Disorder .........................      13.00 Perc.
PLAT711_ALERT_1_C BOND    Unknown or Inconsistent Label ..........          M
                    M      O2
PLAT711_ALERT_1_C BOND    Unknown or Inconsistent Label ..........          M
                    M      O2
PLAT711_ALERT_1_C BOND    Unknown or Inconsistent Label ..........          M
                    M      O1
PLAT711_ALERT_1_C BOND    Unknown or Inconsistent Label ..........          M
                    M      O1
PLAT711_ALERT_1_C BOND    Unknown or Inconsistent Label ..........          M
                    M      O2
PLAT711_ALERT_1_C BOND    Unknown or Inconsistent Label ..........          M
                    M      O2
PLAT711_ALERT_1_C BOND    Unknown or Inconsistent Label ..........          M
                    O1     M
PLAT711_ALERT_1_C BOND    Unknown or Inconsistent Label ..........          M
                    O2     M
PLAT712_ALERT_1_C ANGLE   Unknown or Inconsistent Label ..........          M
                    O2     M      O2
PLAT712_ALERT_1_C ANGLE   Unknown or Inconsistent Label ..........          M
                    O2     M      O1
PLAT712_ALERT_1_C ANGLE   Unknown or Inconsistent Label ..........          M
                    O2     M      O1
PLAT712_ALERT_1_C ANGLE   Unknown or Inconsistent Label ..........          M
                    O2     M      O1
PLAT712_ALERT_1_C ANGLE   Unknown or Inconsistent Label ..........          M
                    O2     M      O1
PLAT712_ALERT_1_C ANGLE   Unknown or Inconsistent Label ..........          M
                    O1     M      O1
PLAT712_ALERT_1_C ANGLE   Unknown or Inconsistent Label ..........          M
                    O2     M      O2
PLAT712_ALERT_1_C ANGLE   Unknown or Inconsistent Label ..........          M
                    O2     M      O2
PLAT712_ALERT_1_C ANGLE   Unknown or Inconsistent Label ..........          M
                    O1     M      O2
PLAT712_ALERT_1_C ANGLE   Unknown or Inconsistent Label ..........          M
                    O1     M      O2
PLAT712_ALERT_1_C ANGLE   Unknown or Inconsistent Label ..........          M
                    O2     M      O2
PLAT712_ALERT_1_C ANGLE   Unknown or Inconsistent Label ..........          M
                    O2     M      O2
PLAT712_ALERT_1_C ANGLE   Unknown or Inconsistent Label ..........          M
                    O1     M      O2
PLAT712_ALERT_1_C ANGLE   Unknown or Inconsistent Label ..........          M
                    O1     M      O2
PLAT712_ALERT_1_C ANGLE   Unknown or Inconsistent Label ..........          M
                    O2     M      O2
PLAT712_ALERT_1_C ANGLE   Unknown or Inconsistent Label ..........          M
                    O2     M      C
PLAT712_ALERT_1_C ANGLE   Unknown or Inconsistent Label ..........          M
                    O2     M      C
PLAT712_ALERT_1_C ANGLE   Unknown or Inconsistent Label ..........          M
                    O1     M      C
PLAT712_ALERT_1_C ANGLE   Unknown or Inconsistent Label ..........          M
                    O1     M      C
PLAT712_ALERT_1_C ANGLE   Unknown or Inconsistent Label ..........          M
                    O2     M      C
PLAT712_ALERT_1_C ANGLE   Unknown or Inconsistent Label ..........          M
                    O2     M      C
PLAT712_ALERT_1_C ANGLE   Unknown or Inconsistent Label ..........          M
                    O2     M      C
PLAT712_ALERT_1_C ANGLE   Unknown or Inconsistent Label ..........          M
                    O2     M      C
PLAT712_ALERT_1_C ANGLE   Unknown or Inconsistent Label ..........          M
                    O1     M      C
PLAT712_ALERT_1_C ANGLE   Unknown or Inconsistent Label ..........          M
                    O1     M      C
PLAT712_ALERT_1_C ANGLE   Unknown or Inconsistent Label ..........          M
                    O2     M      C
PLAT712_ALERT_1_C ANGLE   Unknown or Inconsistent Label ..........          M
                    O2     M      C

   0 ALERT level A = In general: serious problem
   0 ALERT level B = Potentially serious problem
  44 ALERT level C = Check and explain
   0 ALERT level G = General alerts; check

  41 ALERT type 1 CIF construction/syntax error, inconsistent or missing data
   1 ALERT type 2 Indicator that the structure model may be wrong or deficient
   1 ALERT type 3 Indicator that the structure quality may be low
   1 ALERT type 4 Improvement, methodology, query or suggestion
   0 ALERT type 5 Informative message, check

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Computing details

Data collection: CAD-4 EXPRESS (Enraf–Nonius, 1994); cell refinement: CAD-4 EXPRESS; data reduction: XCAD4 (Harms & Wocadlo, 1995); program(s) used to solve structure: SIR2002 (Burla et al., 2003); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: DIAMOND (Brandenburg & Berndt, 2001) and PLATON (Spek, 2003); software used to prepare material for publication: WinGX (Farrugia, 1999).

Anhydrous Barium strontium oxalate

Crystal data

C2Ba0.741O4Sr0.259	F(000) = 381.0
Mr = 212.43	Dx = 3.694 Mg m^−3
Monoclinic, C2/c	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -C 2yc	Cell parameters from 1137 reflections
a = 10.348 (5) Å	θ = 4.4–30.0°
b = 5.489 (5) Å	µ = 11.23 mm^−1
c = 8.218 (5) Å	T = 296 K
β = 125.09 (5)°	Cube, colourless
V = 382.0 (5) Å^3	0.13 × 0.13 × 0.13 mm
Z = 4

Data collection

Enraf–Nonius MACH3 diffractometer	Rint = 0.053
Radiation source: X-ray_tube	θmax = 30.0°, θmin = 4.4°
Graphite monochromator	h = −14→14
ω/2θ scans	k = −7→7
1137 measured reflections	l = −8→11
559 independent reflections	3 standard reflections every 200 reflections
509 reflections with I > 2σ(I)	intensity decay: 1.2%

Refinement

Refinement on F^2	Primary atom site location: structure-invariant direct methods
Least-squares matrix: full	Secondary atom site location: difference Fourier map
R[F^2 > 2σ(F^2)] = 0.026	w = 1/[σ^2(Fo^2) + (0.0367P)^2] where P = (Fo^2 + 2Fc^2)/3
wR(F^2) = 0.077	(Δ/σ)max < 0.001
S = 1.31	Δρmax = 1.72 e Å^−3
559 reflections	Δρmin = −0.64 e Å^−3
35 parameters	Extinction correction: SHELXL97
1 restraint	Extinction coefficient: none

Special details

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 (Ų)

	x	y	z	Uiso*/Ueq	Occ. (<1)
Ba	0.5000	0.12007 (7)	0.2500	0.02160 (16)	0.741 (7)
Sr	0.5000	0.12007 (7)	0.2500	0.02160 (16)	0.259 (7)
O1	0.2545 (4)	−0.4748 (7)	−0.1459 (6)	0.0263 (7)
O2	0.4326 (4)	−0.1896 (6)	0.0406 (5)	0.0214 (6)
C	0.3032 (5)	−0.2978 (8)	−0.0302 (7)	0.0179 (7)

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Ba	0.0150 (2)	0.0200 (2)	0.0225 (2)	0.000	0.00661 (18)	0.000
Sr	0.0150 (2)	0.0200 (2)	0.0225 (2)	0.000	0.00661 (18)	0.000
O1	0.0170 (15)	0.0279 (16)	0.0313 (18)	−0.0032 (15)	0.0124 (15)	−0.0110 (17)
O2	0.0138 (13)	0.0269 (15)	0.0223 (15)	−0.0049 (14)	0.0097 (13)	−0.0077 (14)
C	0.0113 (16)	0.0201 (17)	0.0164 (17)	0.0016 (16)	0.0046 (14)	0.0010 (16)

Geometric parameters (Å, º)

M—O2	2.226 (4)	Ba—Sr^iv	4.315 (2)
M—O2^i	2.226 (4)	Ba—Ba^iv	4.315 (2)
M—O1^ii	2.390 (4)	O1—C	1.245 (6)
M—O1^iii	2.390 (4)	O1—M^ii	2.390 (4)
M—O2^iv	2.872 (3)	O2—C	1.261 (5)
M—O2^v	2.872 (3)	O2—M^iv	2.872 (3)
Ba—C	3.053 (5)	C—C^ii	1.536 (8)
Ba—C^i	3.053 (5)	C—Ba^ii	3.117 (5)
Ba—C^ii	3.117 (5)	C—Sr^ii	3.117 (5)
Ba—C^iii	3.117 (5)
O2—M—O2^i	80.47 (2)	O2^v—Ba—C^iii	103.77 (10)
O2—M—O1^ii	71.18 (12)	C—Ba—C^iii	91.35 (6)
O2^i—M—O1^ii	79.23 (13)	C^i—Ba—C^iii	28.81 (14)
O2—M—O1^iii	79.23 (13)	C^ii—Ba—C^iii	110.86 (17)
O2^i—M—O1^iii	71.18 (12)	O2—Ba—Sr^iv	37.08 (8)
O1^ii—M—O1^iii	141.02 (18)	O2^i—Ba—Sr^iv	109.35 (10)
O2—M—O2^iv	64.95 (14)	O1^ii—Ba—Sr^iv	99.22 (8)
O2^i—M—O2^iv	128.78 (9)	O1^iii—Ba—Sr^iv	68.65 (9)
O1^ii—M—O2^iv	119.39 (11)	O2^v—Ba—Sr^iv	164.84 (7)
O1^iii—M—O2^iv	66.29 (11)	C—Ba—Sr^iv	54.37 (7)
O2—M—O2^v	128.78 (9)	C^i—Ba—Sr^iv	97.09 (9)
O2^i—M—O2^v	64.95 (14)	C^ii—Ba—Sr^iv	79.96 (8)
O1^ii—M—O2^v	66.29 (11)	C^iii—Ba—Sr^iv	80.07 (8)
O1^iii—M—O2^v	119.39 (11)	O2—Ba—Ba^iv	37.08 (8)
O2^iv—M—O2^v	164.73 (14)	O2^i—Ba—Ba^iv	109.35 (10)
O2—M—C	21.05 (11)	O1^ii—Ba—Ba^iv	99.22 (8)
O2^i—M—C	77.65 (14)	O1^iii—Ba—Ba^iv	68.65 (9)
O1^ii—M—C	50.14 (11)	O2^v—Ba—Ba^iv	164.84 (7)
O1^iii—M—C	98.01 (13)	C—Ba—Ba^iv	54.37 (7)
O2^iv—M—C	81.27 (11)	C^i—Ba—Ba^iv	97.09 (9)
O2^v—M—C	110.57 (11)	C^ii—Ba—Ba^iv	79.96 (8)
O2—M—C^i	77.65 (14)	C^iii—Ba—Ba^iv	80.07 (8)
O2^i—M—C^i	21.05 (11)	Sr^iv—Ba—Ba^iv	0.0
O1^ii—M—C^i	98.01 (13)	C—O1—Sr^ii	114.4 (3)
O1^iii—M—C^i	50.14 (11)	C—O1—Ba^ii	114.4 (3)
O2^iv—M—C^i	110.57 (10)	C—O2—Ba	119.6 (3)
O2^v—M—C^i	81.27 (11)	C—O2—Sr^iv	112.4 (3)
C—Ba—C^i	82.58 (18)	Ba—O2—Sr^iv	115.06 (14)
O2—Ba—C^ii	49.86 (11)	C—O2—Ba^iv	112.4 (3)
O2^i—Ba—C^ii	77.20 (13)	Ba—O2—Ba^iv	115.05 (14)
O1^ii—Ba—C^ii	21.33 (11)	O1—C—O2	125.2 (4)
O1^iii—Ba—C^ii	123.56 (13)	O1—C—C^ii	117.5 (5)
O2^iv—Ba—C^ii	103.77 (11)	O2—C—C^ii	117.3 (5)
O2^v—Ba—C^ii	84.99 (11)	O1—C—Ba	164.5 (3)
C—Ba—C^ii	28.81 (14)	C^ii—C—Ba	77.9 (3)
C^i—Ba—C^ii	91.35 (6)	O2—C—Ba^ii	169.4 (3)
O2—Ba—C^iii	77.20 (13)	C^ii—C—Ba^ii	73.3 (3)
O2^i—Ba—C^iii	49.86 (11)	Ba—C—Ba^ii	151.19 (14)
O1^ii—Ba—C^iii	123.56 (13)	O2—C—Sr^ii	169.4 (3)
O1^iii—Ba—C^iii	21.33 (11)	C^ii—C—Sr^ii	73.3 (3)
O2^iv—Ba—C^iii	84.99 (11)	Ba—C—Sr^ii	151.19 (14)

Symmetry codes: (i) −x+1, y, −z+1/2; (ii) −x+1/2, −y−1/2, −z; (iii) x+1/2, −y−1/2, z+1/2; (iv) −x+1, −y, −z; (v) x, −y, z+1/2.