New oxybromide cobaltites with layered perovskite-related structures: 18R-Ba₆Co₅BrO₁₄ and 14H-Ba₇Co₆BrO₁₇

Single crystals of the title compounds were prepared by solid–solid reaction using BaBr₂ flux at 1373 K. The structures of these two new cobaltites were solved and refined. The two compounds are built from a close-packing of [BaO₃] and [BaOBr] layers with stacking sequences (c′chhcc′)₃ and (c′chhhcc′)₂ for the 18R and 14H structures, respectively, which create Co₃O₁₂ trimers or Co₄O₁₅ tetramers of face-sharing octahedra connected at their extremities to isolated tetrahedra by corner-sharing. These new materials are strongly related to the 5H-Ba₅Co₅O₁₄/12H-Ba_0.9CoO_2.6 and 10H-Ba₅Co₅ClO₁₃/6H-Ba₆Co₆ClO₁₆ materials, with the existence of common blocks. In Ba₆Co₅BrO₁₄ and Ba₇Co₆BrO₁₇, all the atoms in the vicinity of the [BaOBr] layers are disordered, whereas the rest of the structure is perfectly ordered.

Computing details

For both compounds, program(s) used to refine structure: (Jana2000; Petricek and Dusek, 2000); software used to prepare material for publication: (Jana2000; Petricek and Dusek, 2000).

(I)

Crystal data

Ba7BrCo6O17	F(000) = 1450
Mr = 1666.9	Dx = 5.940 Mg m^−3
Hexagonal, P63/mmc	Mo Kα radiation, λ = 0.71069 Å
Hall symbol: -P 6c;-2c	µ = 21.93 mm^−1
a = 5.6611 (1) Å	T = 293 K
c = 33.5672 (8) Å	Hexagonal platelets, black
V = 931.64 (3) Å^3	0.12 × 0.09 × 0.06 mm
Z = 2

Data collection

Bruker APEX 11, CCD 4K diffractometer	1045 reflections with I > 3σ(I)
φ and ω scans	Rint = 0.045
Absorption correction: multi-scan	θmax = 39.9°, θmin = 1.2°
Tmin = 0.139, Tmax = 0.518	h = −10→10
11909 measured reflections	k = −5→8
1158 independent reflections	l = −60→60

Refinement

Refinement on F	Weighting scheme based on measured s.u.'s w = 1/σ^2(F)
R[F^2 > 2σ(F^2)] = 0.048	(Δ/σ)max = 0.001
wR(F^2) = 0.066	Δρmax = 7.98 e Å^−3
S = 4.70	Δρmin = −5.50 e Å^−3
1158 reflections	Extinction correction: B-C type 1 Gaussian isotropic (Becker & Coppens, 1974)
53 parameters	Extinction coefficient: 0.028 (8)

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Ų)

	x	y	z	Uiso*/Ueq	Occ. (<1)
Ba1	0	0	0.12114 (2)	0.00937 (16)
Ba2	0.333333	0.666667	0.186738 (18)	0.00824 (15)
Ba3	0	0	0.25	0.0115 (2)
Ba4	0.30479 (11)	0.6096 (2)	0.96009 (3)	0.0134 (5)	0.3333
Co1	0.333333	0.666667	0.85919 (4)	0.0063 (3)
Co2	0.333333	0.666667	0.78574 (4)	0.0057 (3)
Co3	0.333333	0.666667	0.08606 (5)	0.0089 (3)
Br1	0	0	0.4804 (4)	0.035 (2)	0.437 (15)
Br2	0	0	0.5	0.023 (6)	0.13 (3)
O1	0.4955 (4)	0.9911 (9)	0.89323 (17)	0.0139 (13)
O2	0.1872 (4)	0.3744 (8)	0.82175 (13)	0.0080 (11)
O3	0.5170 (6)	0.0339 (12)	0.25	0.0092 (17)
O4	0.2798 (17)	0.560 (3)	0.0343 (5)	0.036 (7)	0.3333

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Ba1	0.00775 (19)	0.00775 (19)	0.0126 (3)	0.00387 (10)	0	0
Ba2	0.00653 (19)	0.00653 (19)	0.0117 (3)	0.00326 (10)	0	0
Ba3	0.0070 (2)	0.0070 (2)	0.0205 (4)	0.00348 (12)	0	0
Ba4	0.0134 (4)	0.0184 (8)	0.0100 (3)	0.0092 (4)	−0.00033 (16)	−0.0007 (3)
Co1	0.0058 (3)	0.0058 (3)	0.0072 (5)	0.00292 (17)	0	0
Co2	0.0046 (3)	0.0046 (3)	0.0078 (5)	0.00231 (17)	0	0
Co3	0.0086 (4)	0.0086 (4)	0.0096 (6)	0.0043 (2)	0	0
Br1	0.0261 (12)	0.0261 (12)	0.053 (7)	0.0130 (6)	0	0
Br2	0.033 (7)	0.033 (7)	0.003 (13)	0.017 (3)	0	0
O1	0.0129 (14)	0.0121 (19)	0.016 (2)	0.0061 (10)	−0.0021 (9)	−0.0043 (17)
O2	0.0096 (14)	0.0042 (16)	0.0083 (15)	0.0021 (8)	0.0004 (7)	0.0009 (13)
O3	0.0105 (19)	0.010 (3)	0.007 (2)	0.0049 (13)	0	0
O4	0.053 (9)	0.033 (10)	0.015 (7)	0.017 (5)	0.000 (3)	0.001 (7)

(II)

Crystal data

Ba6BrCo5O14	F(000) = 1854
Mr = 1422.6	Dx = 5.920 Mg m^−3
Trigonal, R3m	Mo Kα radiation, λ = 0.71069 Å
Hall symbol: -R 3;-2"	µ = 22.16 mm^−1
a = 5.6578 (3) Å	T = 293 K
c = 43.166 (4) Å	Hexagonal platelets, black
V = 1196.65 (14) Å^3	0.13 × 0.10 × 0.06 mm
Z = 3

Data collection

Bruker APEX 11, CCD 4K diffractometer	1117 reflections with I > 3σ(I)
φ and ω scans	Rint = 0.045
Absorption correction: multi-scan	θmax = 43.8°, θmin = 1.4°
Tmin = 0.128, Tmax = 0.265	h = −5→10
13868 measured reflections	k = −10→10
1232 independent reflections	l = −80→84

Refinement

Refinement on F	Weighting scheme based on measured s.u.'s w = 1/σ^2(F)
R[F^2 > 2σ(F^2)] = 0.032	(Δ/σ)max = 0.0004
wR(F^2) = 0.047	Δρmax = 4.36 e Å^−3
S = 3.86	Δρmin = −4.12 e Å^−3
1232 reflections	Extinction correction: B-C type 1 Lorentzian isotropic (Becker & Coppens, 1974)
46 parameters	Extinction coefficient: 0.023 (5)

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Ų)

	x	y	z	Uiso*/Ueq	Occ. (<1)
Ba1	0	0	0.093083 (9)	0.00958 (9)
Ba2	0	0	0.810512 (9)	0.00961 (9)
Ba3	0.30796 (8)	−0.30796 (8)	0.031094 (14)	0.0153 (2)	0.3333
Co1	0	0	0.44255 (2)	0.00649 (16)
Co2	0	0	0.5	0.0061 (2)
Co3	0	0	0.73297 (2)	0.00947 (18)
Br1	0	0	0.98409 (11)	0.0225 (19)	0.23 (3)
Br2	0	0	0	0.097 (14)	0.55 (5)
O1	0.4941 (2)	−0.4941 (2)	0.08305 (7)	0.0152 (8)
O2	0.4809 (2)	−0.4809 (2)	0.19494 (6)	0.0091 (6)
O3	0.2800 (10)	−0.2800 (10)	0.9726 (2)	0.031 (3)	0.3333

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Ba1	0.00808 (11)	0.00808 (11)	0.01257 (15)	0.00404 (6)	0	0
Ba2	0.00743 (11)	0.00743 (11)	0.01396 (16)	0.00372 (6)	0	0
Ba3	0.0154 (3)	0.0154 (3)	0.0119 (2)	0.00541 (19)	0.00141 (10)	−0.00141 (10)
Co1	0.00549 (19)	0.00549 (19)	0.0085 (3)	0.00274 (9)	0	0
Co2	0.0053 (2)	0.0053 (2)	0.0077 (4)	0.00266 (12)	0	0
Co3	0.0088 (2)	0.0088 (2)	0.0108 (3)	0.00440 (11)	0	0
Br1	0.022 (2)	0.022 (2)	0.023 (4)	0.0112 (10)	0	0
Br2	0.0425 (19)	0.0425 (19)	0.21 (4)	0.0212 (9)	0	0
O1	0.0137 (9)	0.0137 (9)	0.0217 (12)	0.0096 (9)	0.0014 (5)	−0.0014 (5)
O2	0.0093 (7)	0.0093 (7)	0.0102 (8)	0.0059 (8)	−0.0006 (4)	0.0006 (4)
O3	0.036 (4)	0.036 (4)	0.010 (3)	0.009 (4)	0.0028 (17)	−0.0028 (17)