The title compound, dicaesium gold(I) gold(III) hexabromide or dicaesium dibromoaurate(I) tetrabromoaurate(III), Cs
2[Au
IBr
2][Au
IIIBr
4], has a distorted perovskite-type structure which is isotypic with its chloride and iodide analogues, Cs
2Au
IAu
IIIX6 (
X is Cl or I). The structure contains compressed and elongated [AuBr
6] 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 [Au
IBr
2]
− and [Au
IIIBr
4]
−. Structural parameters indicating the mixed-valence distortion of Au
I and Au
III 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 2
1/2a/
c = 0.9704 (1), is also intermediate between those of the chloride and the iodide.
Supporting information
Key indicators
- Single-crystal X-ray study
- T = 296 K
- Mean (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
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 m−3 |
Mr = 1139.17 | Melting point: not measured K |
Tetragonal, I4/mmm | Mo Kα radiation, λ = 0.71069 Å |
Hall symbol: -I 4 2 | Cell parameters from 25 reflections |
a = 7.7592 (8) Å | θ = 10.4–14.6° |
c = 11.3079 (13) Å | µ = 44.35 mm−1 |
V = 680.79 (13) Å3 | T = 296 K |
Z = 2 | Plate, gold |
F(000) = 956 | 0.23 × 0.18 × 0.08 mm |
Data collection top
Rigaku AFC-5S diffractometer | 335 reflections with I > 2σ(I) |
Radiation source: X-ray tube | Rint = 0.003 |
Graphite monochromator | θmax = 35.0°, θmin = 3.2° |
θ/2θ scans | h = 0→12 |
Absorption correction: gaussian (Coppens et al., 1965) | k = 0→8 |
Tmin = 0.011, Tmax = 0.088 | l = 0→18 |
949 measured reflections | 3 standard reflections every 100 reflections |
474 independent reflections | intensity decay: none |
Refinement top
Refinement on F2 | Primary 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) = 0.170 | Δρmax = 5.19 e Å−3 |
S = 1.04 | Δρmin = −6.01 e Å−3 |
474 reflections | Extinction correction: SHELXL97 (Sheldrick, 1997), Fc*=kFc[1+0.001xFc2λ3/sin(2θ)]-1/4 |
15 parameters | Extinction 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 | x | y | z | Uiso*/Ueq | |
Au1 | 0.0000 | 0.0000 | 0.0000 | 0.0225 (4) | |
Au2 | 0.5000 | 0.5000 | 0.0000 | 0.0252 (4) | |
Br1 | 0.2220 (2) | 0.2220 (2) | 0.0000 | 0.0421 (7) | |
Br2 | 0.5000 | 0.5000 | 0.2122 (4) | 0.0445 (10) | |
Cs | 0.0000 | 0.5000 | 0.2500 | 0.0475 (6) | |
Atomic displacement parameters (Å2) top | U11 | U22 | U33 | U12 | U13 | U23 |
Au1 | 0.0211 (5) | 0.0211 (5) | 0.0253 (7) | 0.000 | 0.000 | 0.000 |
Au2 | 0.0256 (5) | 0.0256 (5) | 0.0245 (8) | 0.000 | 0.000 | 0.000 |
Br1 | 0.0355 (8) | 0.0355 (8) | 0.0553 (15) | −0.0132 (10) | 0.000 | 0.000 |
Br2 | 0.0526 (15) | 0.0526 (15) | 0.0285 (14) | 0.000 | 0.000 | 0.000 |
Cs | 0.0466 (8) | 0.0466 (8) | 0.0494 (12) | 0.000 | 0.000 | 0.000 |
Geometric parameters (Å, º) top
Au1—Br1 | 2.436 (3) | Br1—Br2 | 3.881 (3) |
Au1—Br1i | 2.436 (3) | Br1—Br2vi | 3.881 (3) |
Au1—Br1ii | 2.436 (3) | Br1—Br2v | 4.065 (4) |
Au1—Br1iii | 2.436 (3) | Br1—Br2iv | 4.065 (4) |
Au1—Br2iv | 3.254 (4) | Br1—Br1viii | 4.314 (4) |
Au1—Br2v | 3.254 (4) | Br1—Br1vii | 4.314 (4) |
Au2—Br2vi | 2.400 (4) | Br2—Au1ix | 3.254 (4) |
Au2—Br2 | 2.400 (4) | Br2—Br1viii | 3.881 (3) |
Au2—Br1vi | 3.050 (3) | Br2—Br1vii | 3.881 (3) |
Au2—Br1 | 3.050 (3) | Br2—Br1vi | 3.881 (3) |
Au2—Br1vii | 3.050 (3) | Br2—Br1ix | 4.065 (4) |
Au2—Br1viii | 3.050 (3) | Br2—Br1x | 4.065 (4) |
Br1—Br1ii | 3.446 (4) | Br2—Br1xi | 4.065 (4) |
Br1—Br1iii | 3.446 (4) | Br2—Br1iv | 4.065 (4) |
| | | |
Br1—Au1—Br1i | 180.00 (6) | Br2vi—Au2—Br1vi | 90.0 |
Br1—Au1—Br1ii | 90.0 | Br2—Au2—Br1vi | 90.0 |
Br1i—Au1—Br1ii | 90.0 | Br2vi—Au2—Br1 | 90.0 |
Br1—Au1—Br1iii | 90.0 | Br2—Au2—Br1 | 90.0 |
Br1i—Au1—Br1iii | 90.0 | Br1vi—Au2—Br1 | 180.0 |
Br1ii—Au1—Br1iii | 180.00 (6) | Br2vi—Au2—Br1vii | 90.0 |
Br1—Au1—Br2iv | 90.0 | Br2—Au2—Br1vii | 90.0 |
Br1i—Au1—Br2iv | 90.0 | Br1vi—Au2—Br1vii | 90.0 |
Br1ii—Au1—Br2iv | 90.0 | Br1—Au2—Br1vii | 90.0 |
Br1iii—Au1—Br2iv | 90.0 | Br2vi—Au2—Br1viii | 90.0 |
Br1—Au1—Br2v | 90.0 | Br2—Au2—Br1viii | 90.0 |
Br1i—Au1—Br2v | 90.0 | Br1vi—Au2—Br1viii | 90.0 |
Br1ii—Au1—Br2v | 90.0 | Br1—Au2—Br1viii | 90.0 |
Br1iii—Au1—Br2v | 90.0 | Br1vii—Au2—Br1viii | 180.0 |
Br2iv—Au1—Br2v | 180.0 | Au1—Br1—Au2 | 180.0 |
Br2vi—Au2—Br2 | 180.0 | Au2—Br2—Au1ix | 180.0 |
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) x−1/2, y−1/2, z−1/2; (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. |