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The title compound, dicaesium gold(I) gold(III) hexa­bromide or dicaesium dibromo­aurate(I) tetra­bromo­aurate(III), Cs2[AuIBr2][AuIIIBr4], has a distorted perovskite-type structure which is isotypic with its chloride and iodide analogues, Cs2AuIAuIIIX6 (X is Cl or I). The structure contains compressed and elongated [AuBr6] octa­hedra stacked alternately along the [001] and [110] directions by sharing all the corner Br ions. The compound is also characterized by the assembly of the gold complex ions [AuIBr2] and [AuIIIBr4]. Structural parameters indicating the mixed-valence distortion of AuI and AuIII due to displacement of two crystallographically independent halide (X) ions from the mid-point between the two adjacent Au ions, expressed by (Au—X)/(Au...X), are 0.738 (2) along the c axis and 0.799 (1) in the ab plane. These values show that the mixed-valence distortion of the title bromide is inter­mediate between those of the chloride and the iodide. The distortion of the title bromide from the cubic system to the tetra­gonal system, expressed by 21/2a/c = 0.9704 (1), is also inter­mediate between those of the chloride and the iodide.

Supporting information

cif

Crystallographic Information File (CIF) https://doi.org/10.1107/S1600536805016594/wm6065sup1.cif
Contains datablocks global, I

hkl

Structure factor file (CIF format) https://doi.org/10.1107/S1600536805016594/wm6065Isup2.hkl
Contains datablock I

Key indicators

  • Single-crystal X-ray study
  • T = 296 K
  • Mean [sigma](u-Br) = 0.002 Å
  • R factor = 0.064
  • wR factor = 0.170
  • Data-to-parameter ratio = 31.6

checkCIF/PLATON results

No syntax errors found



Alert level C DIFMN02_ALERT_2_C The minimum difference density is < -0.1*ZMAX*0.75 _refine_diff_density_min given = -6.006 Test value = -5.925 DIFMN03_ALERT_1_C The minimum difference density is < -0.1*ZMAX*0.75 The relevant atom site should be identified. 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 ............ 2.00 Ratio PLAT098_ALERT_2_C Minimum (Negative) Residual Density ............ -6.01 e/A   3 PLAT241_ALERT_2_C Check High Ueq as Compared to Neighbors for Br1 PLAT242_ALERT_2_C Check Low Ueq as Compared to Neighbors for Au2
Alert level G ABSTM02_ALERT_3_G The ratio of expected to reported Tmax/Tmin(RR) is > 2.00 Tmin and Tmax reported: 0.011 0.088 Tmin and Tmax expected: 0.000 0.029 RR = 7.019 Please check that your absorption correction is appropriate. REFLT03_ALERT_1_G ALERT: Expected hkl max differ from CIF values From the CIF: _diffrn_reflns_theta_max 34.99 From the CIF: _reflns_number_total 474 From the CIF: _diffrn_reflns_limit_ max hkl 12. 8. 18. From the CIF: _diffrn_reflns_limit_ min hkl 0. 0. 0. TEST1: Expected hkl limits for theta max Calculated maximum hkl 12. 12. 18. Calculated minimum hkl -12. -12. -18.
0 ALERT level A = In general: serious problem 0 ALERT level B = Potentially serious problem 8 ALERT level C = Check and explain 2 ALERT level G = General alerts; check 5 ALERT type 1 CIF construction/syntax error, inconsistent or missing data 4 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 0 ALERT type 4 Improvement, methodology, query or suggestion

Computing details top

Data collection: MSC/AFC Diffractometer Control Software (Molecular Structure Corporation, 1988); cell refinement: MSC/AFC Diffractometer Control Software; data reduction: local program F2-AFC (Matsushita, 1998); program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: ORTEP-3 (Farrugia, 1997) and DIAMOND (Brandenburg, 2005); software used to prepare material for publication: SHELXL97.

Dicaesium dibromoaurate(I) tetrabromoaurate(III) top
Crystal data top
Cs2[AuBr2][AuBr4]Dx = 5.56 Mg m3
Mr = 1139.17Melting point: not measured K
Tetragonal, I4/mmmMo Kα radiation, λ = 0.71069 Å
Hall symbol: -I 4 2Cell parameters from 25 reflections
a = 7.7592 (8) Åθ = 10.4–14.6°
c = 11.3079 (13) ŵ = 44.35 mm1
V = 680.79 (13) Å3T = 296 K
Z = 2Plate, gold
F(000) = 9560.23 × 0.18 × 0.08 mm
Data collection top
Rigaku AFC-5S
diffractometer
335 reflections with I > 2σ(I)
Radiation source: X-ray tubeRint = 0.003
Graphite monochromatorθmax = 35.0°, θmin = 3.2°
θ/2θ scansh = 012
Absorption correction: gaussian
(Coppens et al., 1965)
k = 08
Tmin = 0.011, Tmax = 0.088l = 018
949 measured reflections3 standard reflections every 100 reflections
474 independent reflections intensity decay: none
Refinement top
Refinement on F2Primary atom site location: heavy-atom method
Least-squares matrix: full w = 1/[σ2(Fo2) + (0.1105P)2]
where P = (Fo2 + 2Fc2)/3
R[F2 > 2σ(F2)] = 0.064(Δ/σ)max < 0.001
wR(F2) = 0.170Δρmax = 5.19 e Å3
S = 1.04Δρmin = 6.01 e Å3
474 reflectionsExtinction correction: SHELXL97 (Sheldrick, 1997), Fc*=kFc[1+0.001xFc2λ3/sin(2θ)]-1/4
15 parametersExtinction coefficient: 0.0014 (4)
0 restraints
Special details top

Refinement. Refinement of F2 against ALL 474 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>2σ(F2) is used only for calculating R-factors(gt) etc. and is not relevant to the choice of reflections for refinement.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top
xyzUiso*/Ueq
Au10.00000.00000.00000.0225 (4)
Au20.50000.50000.00000.0252 (4)
Br10.2220 (2)0.2220 (2)0.00000.0421 (7)
Br20.50000.50000.2122 (4)0.0445 (10)
Cs0.00000.50000.25000.0475 (6)
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
Au10.0211 (5)0.0211 (5)0.0253 (7)0.0000.0000.000
Au20.0256 (5)0.0256 (5)0.0245 (8)0.0000.0000.000
Br10.0355 (8)0.0355 (8)0.0553 (15)0.0132 (10)0.0000.000
Br20.0526 (15)0.0526 (15)0.0285 (14)0.0000.0000.000
Cs0.0466 (8)0.0466 (8)0.0494 (12)0.0000.0000.000
Geometric parameters (Å, º) top
Au1—Br12.436 (3)Br1—Br23.881 (3)
Au1—Br1i2.436 (3)Br1—Br2vi3.881 (3)
Au1—Br1ii2.436 (3)Br1—Br2v4.065 (4)
Au1—Br1iii2.436 (3)Br1—Br2iv4.065 (4)
Au1—Br2iv3.254 (4)Br1—Br1viii4.314 (4)
Au1—Br2v3.254 (4)Br1—Br1vii4.314 (4)
Au2—Br2vi2.400 (4)Br2—Au1ix3.254 (4)
Au2—Br22.400 (4)Br2—Br1viii3.881 (3)
Au2—Br1vi3.050 (3)Br2—Br1vii3.881 (3)
Au2—Br13.050 (3)Br2—Br1vi3.881 (3)
Au2—Br1vii3.050 (3)Br2—Br1ix4.065 (4)
Au2—Br1viii3.050 (3)Br2—Br1x4.065 (4)
Br1—Br1ii3.446 (4)Br2—Br1xi4.065 (4)
Br1—Br1iii3.446 (4)Br2—Br1iv4.065 (4)
Br1—Au1—Br1i180.00 (6)Br2vi—Au2—Br1vi90.0
Br1—Au1—Br1ii90.0Br2—Au2—Br1vi90.0
Br1i—Au1—Br1ii90.0Br2vi—Au2—Br190.0
Br1—Au1—Br1iii90.0Br2—Au2—Br190.0
Br1i—Au1—Br1iii90.0Br1vi—Au2—Br1180.0
Br1ii—Au1—Br1iii180.00 (6)Br2vi—Au2—Br1vii90.0
Br1—Au1—Br2iv90.0Br2—Au2—Br1vii90.0
Br1i—Au1—Br2iv90.0Br1vi—Au2—Br1vii90.0
Br1ii—Au1—Br2iv90.0Br1—Au2—Br1vii90.0
Br1iii—Au1—Br2iv90.0Br2vi—Au2—Br1viii90.0
Br1—Au1—Br2v90.0Br2—Au2—Br1viii90.0
Br1i—Au1—Br2v90.0Br1vi—Au2—Br1viii90.0
Br1ii—Au1—Br2v90.0Br1—Au2—Br1viii90.0
Br1iii—Au1—Br2v90.0Br1vii—Au2—Br1viii180.0
Br2iv—Au1—Br2v180.0Au1—Br1—Au2180.0
Br2vi—Au2—Br2180.0Au2—Br2—Au1ix180.0
Symmetry codes: (i) x, y, z; (ii) x, y, z; (iii) x, y, z; (iv) x+1/2, y+1/2, z+1/2; (v) x1/2, y1/2, z1/2; (vi) x+1, y+1, z; (vii) x+1, y, z; (viii) x, y+1, z; (ix) x+1/2, y+1/2, z+1/2; (x) x+1/2, y+1/2, z+1/2; (xi) x+1/2, y+1/2, z+1/2.
 

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