Superspace description of the modulated structure of the metal-salt-hybrid Bi_7 − δNi₂Br_{5 − 2δ} (δ = 1/9)

The compound Bi_7 − δNi₂Br_{5 − 2δ} = (Bi₃Ni)₂[Bi_1 − δBr₄]Br_1 −2δ (δ = 1/9) is a sub-bromide of the intermetallic phase Bi₃Ni. Its crystal structure contains metallic rods, [Bi₃Ni], which are embedded in a salt-like matrix of bromido-bismuthate(III) and bromide anions. The non-stoichiometry originates from the variation of the number n of trans edge-sharing octahedra in the [Bi_nBr_4n + 2]^{(n + 2)−} oligomers (3 ≤ n ≤ 5), as well as from vacancies on the sites of the isolated Br atoms. The simplified structure is described in the orthorhombic space group Cmcm with a = 4.0660 (4), b = 23.305 (3), c = 17.130 (2) Å. It shows a statistical distribution of vacancies and orientational disorder of the concatenated octahedra. By choosing the modulation vector q = a*/9 + b*/2, the additional weak reflections of the diffraction pattern can be indexed. In the [3 + 1]-dimensional superspace group Pmnm(α½0)000, an ordered structure model is achieved. The modulated crystal structure bears a strong resemblance to the somewhat higher oxidized sub-bromide Bi_7 − δNi₂Br₅ (δ = 1/9).

Computing details

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

Figures

(Bi7Ni2Br5average)

Crystal data

Bi6.889Br4.778Ni2	F(000) = 3183
Mr = 1938.8	Dx = 7.941 Mg m^−3
Orthorhombic, Pmnm	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -P -2yca;-2zc	Cell parameters from 14269 reflections
a = 4.0660 (4) Å	θ = 1.8–24.5°
b = 23.305 (3) Å	µ = 88.43 mm^−1
c = 17.130 (2) Å	T = 293 K
V = 1623.2 (3) Å^3	Needle, black
Z = 4	0.6 × 0.08 × 0.02 mm

Data collection

Imaging plate diffractometer STOE IPDS II	1631 independent reflections
Radiation source: fine-focus sealed tube	1075 reflections with I > 3σ(I)
Graphite monochromator	Rint = 0.114
incremental rotation scans	θmax = 24.6°, θmin = 1.5°
Absorption correction: numerical microscopic crystal description optimized with X-SHAPE 1.06 (Stoe, 1999)	h = −4→4
Tmin = 0.02, Tmax = 0.204	k = −27→27
17051 measured reflections	l = −20→20

Refinement

Refinement on F^2	105 parameters
R[F^2 > 2σ(F^2)] = 0.060	Weighting scheme based on measured s.u.'s w = 1/(σ^2(I) + 0.000025I^2)
wR(F^2) = 0.085	(Δ/σ)max = 0.0002
S = 6.06	Δρmax = 2.17 e Å^−3
1631 reflections	Δρmin = −2.30 e Å^−3

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

	x	y	z	Uiso*/Ueq	Occ. (<1)
Bi11	0.75	0.07204 (13)	0.58899 (11)	0.0222 (9)	0.5
Bi21	0.75	0.05552 (13)	0.39189 (10)	0.0218 (8)	0.5
Bi31	0.25	0.14575 (15)	0.47422 (14)	0.0349 (10)	0.5
Ni11	0.25	0.0320 (4)	0.4977 (3)	0.021 (3)	0.5
Bi12	0.75	0.42826 (13)	0.41255 (11)	0.0260 (9)	0.5
Bi22	0.75	0.44695 (15)	0.61086 (12)	0.0324 (10)	0.5
Bi32	0.25	0.35592 (16)	0.52982 (16)	0.0486 (13)	0.5
Ni12	0.25	0.4688 (4)	0.5050 (4)	0.022 (3)	0.5
Br11	0.25	0.0023 (6)	0.25	0.0468 (16)	0.5
Bi41a	0.75	0.2635 (4)	0.25	0.044 (4)	0.273 (11)
Bi41b	0.25	0.2677 (6)	0.25	0.044 (5)	0.169 (9)
Br21a	0.25	0.1759 (11)	0.25	0.042 (2)	0.282 (12)
Br21b	0.25	0.1529 (15)	0.25	0.042 (2)	0.218 (12)
Br31a	0.25	0.3538 (10)	0.25	0.039 (2)	0.282 (12)
Br31b	0.25	0.3995 (10)	0.25	0.039 (2)	0.1652
Br41a	0.75	0.2662 (9)	0.4205 (7)	0.0414 (13)	0.218 (10)
Br41b	0.75	0.2638 (6)	0.3789 (7)	0.0414 (13)	0.267
Br12	0.75	0.5024 (10)	0.25	0.0468 (16)	0.312 (12)
Bi42a	0.25	0.7614 (4)	0.25	0.042 (5)	0.219 (11)
Bi42b	0.75	0.7574 (4)	0.25	0.043 (3)	0.225 (9)
Br22a	0.75	0.6691 (8)	0.25	0.042 (2)	0.312 (11)
Br22b	0.75	0.6297 (11)	0.25	0.042 (2)	0.19 (2)
Br32a	0.75	0.8506 (12)	0.25	0.039 (2)	0.312 (11)
Br32b	0.75	0.8754 (9)	0.25	0.039 (2)	0.271 (16)
Br42a	0.25	0.7612 (7)	0.4116 (7)	0.0414 (13)	0.270 (9)
Br42b	0.25	0.7585 (7)	0.3669 (6)	0.0414 (13)	0.245 (13)

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Bi11	0.0176 (19)	0.0290 (16)	0.0200 (8)	0	0	−0.0049 (10)
Bi21	0.0207 (18)	0.0306 (15)	0.0141 (7)	0	0	0.0029 (9)
Bi31	0.040 (2)	0.0227 (15)	0.0424 (11)	0	0	0.0025 (11)
Ni11	0.029 (6)	0.022 (5)	0.014 (2)	0	0	0.003 (3)
Bi12	0.023 (2)	0.0329 (17)	0.0221 (8)	0	0	−0.0037 (11)
Bi22	0.0177 (19)	0.052 (2)	0.0280 (9)	0	0	0.0106 (12)
Bi32	0.062 (3)	0.0292 (18)	0.0545 (14)	0	0	0.0126 (14)
Ni12	0.005 (5)	0.023 (5)	0.040 (3)	0	0	−0.003 (3)
Br11	0.047 (3)	0.068 (3)	0.0250 (18)	0	0	0
Bi41a	0.073 (10)	0.040 (6)	0.020 (4)	0	0	0
Bi41b	0.088 (13)	0.029 (6)	0.017 (5)	0	0	0
Br21a	0.048 (3)	0.032 (6)	0.0465 (19)	0	0	0
Br21b	0.048 (3)	0.032 (6)	0.0465 (19)	0	0	0
Br31a	0.039 (3)	0.036 (6)	0.0430 (18)	0	0	0
Br31b	0.039 (3)	0.036 (6)	0.0430 (18)	0	0	0
Br41a	0.050 (2)	0.055 (2)	0.019 (2)	0	0	−0.003 (3)
Br41b	0.050 (2)	0.055 (2)	0.019 (2)	0	0	−0.003 (3)
Br12	0.047 (3)	0.068 (3)	0.0250 (18)	0	0	0
Bi42a	0.085 (14)	0.015 (6)	0.026 (5)	0	0	0
Bi42b	0.065 (8)	0.037 (5)	0.028 (4)	0	0	0
Br22a	0.048 (3)	0.032 (6)	0.0465 (19)	0	0	0
Br22b	0.048 (3)	0.032 (6)	0.0465 (19)	0	0	0
Br32a	0.039 (3)	0.036 (6)	0.0430 (18)	0	0	0
Br32b	0.039 (3)	0.036 (6)	0.0430 (18)	0	0	0
Br42a	0.050 (2)	0.055 (2)	0.019 (2)	0	0	−0.003 (3)
Br42b	0.050 (2)	0.055 (2)	0.019 (2)	0	0	−0.003 (3)

Bond lengths (Å)

Bi11—Bi11^i	4.066	Bi41b—Br41b^i	3.003 (9)
Bi11—Bi11^ii	4.066	Bi41b—Br41b	3.003 (9)
Bi11—Bi21	3.398 (3)	Bi41b—Br41b^xii	3.003 (9)
Bi11—Bi21^iii	3.616 (3)	Bi41b—Br41b^xi	3.003 (9)
Bi11—Bi21^iv	3.616 (3)	Br21a—Br21a^i	4.066
Bi11—Bi31	3.309 (3)	Br21a—Br21a^ii	4.066
Bi11—Bi31^ii	3.309 (3)	Br21a—Br21b^i	4.101 (6)
Bi11—Ni11	2.730 (5)	Br21a—Br21b^ii	4.101 (6)
Bi11—Ni11^ii	2.730 (5)	Br21a—Br31a	4.15 (4)
Bi11—Ni11^iii	2.843 (9)	Br21a—Br41a^i	4.135 (19)
Bi11—Br11^iii	3.257 (8)	Br21a—Br41a	4.135 (19)
Bi11—Br32a^v	3.871 (14)	Br21a—Br41a^xii	4.135 (19)
Bi11—Br32a^vi	3.871 (14)	Br21a—Br41a^xi	4.135 (19)
Bi11—Br32b^v	3.639 (7)	Br21a—Br41b^i	3.634 (18)
Bi11—Br32b^vi	3.639 (7)	Br21a—Br41b	3.634 (18)
Bi11—Br42a^v	3.886 (16)	Br21a—Br41b^xii	3.634 (18)
Bi11—Br42b^v	4.020 (16)	Br21a—Br41b^xi	3.634 (18)
Bi21—Bi21^i	4.066	Br21b—Br21b^i	4.066
Bi21—Bi21^ii	4.066	Br21b—Br21b^ii	4.066
Bi21—Bi31	3.247 (3)	Br21b—Br41b^i	3.96 (3)
Bi21—Bi31^ii	3.247 (3)	Br21b—Br41b	3.96 (3)
Bi21—Ni11	2.778 (4)	Br21b—Br41b^xii	3.96 (3)
Bi21—Ni11^ii	2.778 (4)	Br21b—Br41b^xi	3.96 (3)
Bi21—Ni11^iii	2.782 (8)	Br31a—Br31a^i	4.066
Bi21—Br11	3.403 (6)	Br31a—Br31a^ii	4.066
Bi21—Br11^ii	3.403 (6)	Br31a—Br41a^i	4.103 (18)
Bi21—Br21b	3.90 (2)	Br31a—Br41a	4.103 (18)
Bi21—Br21b^ii	3.90 (2)	Br31a—Br41a^xii	4.103 (18)
Bi31—Bi31^i	4.066	Br31a—Br41a^xi	4.103 (18)
Bi31—Bi31^ii	4.066	Br31a—Br41b^i	3.662 (17)
Bi31—Ni11	2.681 (10)	Br31a—Br41b	3.662 (17)
Bi31—Br21a	3.905 (5)	Br31a—Br41b^xii	3.662 (17)
Bi31—Br21b	3.845 (3)	Br31a—Br41b^xi	3.662 (17)
Bi31—Br41a^i	3.586 (16)	Br31a—Br12^i	4.02 (3)
Bi31—Br41a	3.586 (16)	Br31a—Br12	4.02 (3)
Bi31—Br41b^i	3.790 (12)	Br31b—Br31b^i	4.066
Bi31—Br41b	3.790 (12)	Br31b—Br31b^ii	4.066
Bi31—Br42a^vii	3.557 (12)	Br31b—Br12^i	3.14 (3)
Bi31—Br42a^v	3.557 (12)	Br31b—Br12	3.14 (3)
Bi31—Br42b^vii	4.064 (11)	Br41a—Br41a^i	4.066
Bi31—Br42b^v	4.064 (11)	Br41a—Br41a^ii	4.066
Ni11—Ni11^i	4.066	Br41a—Br41b^i	4.128 (3)
Ni11—Ni11^ii	4.066	Br41a—Br41b^ii	4.128 (3)
Ni11—Ni11^viii	2.523 (8)	Br41a—Br42a^v	2.945 (18)
Ni11—Ni11^iii	2.523 (8)	Br41a—Br42b^v	3.687 (16)
Bi12—Bi12^i	4.066	Br41b—Br41b^i	4.066
Bi12—Bi12^ii	4.066	Br41b—Br41b^ii	4.066
Bi12—Bi22	3.425 (3)	Br41b—Br42a^v	3.635 (17)
Bi12—Bi22^v	3.571 (4)	Br12—Br12^i	4.066
Bi12—Bi22^vi	3.571 (4)	Br12—Br12^ii	4.066
Bi12—Bi32	3.318 (3)	Br12—Br22a	3.89 (3)
Bi12—Bi32^ii	3.318 (3)	Br12—Br22b	2.97 (3)
Bi12—Ni12	2.745 (5)	Bi42a—Bi42a^i	4.066
Bi12—Ni12^ii	2.745 (5)	Bi42a—Bi42a^ii	4.066
Bi12—Ni12^v	2.784 (9)	Bi42a—Br22a^i	2.960 (15)
Bi12—Br31a	3.859 (11)	Bi42a—Br22a	2.960 (15)
Bi12—Br31a^ii	3.859 (11)	Bi42a—Br22b^i	3.68 (2)
Bi12—Br31b	3.512 (5)	Bi42a—Br22b	3.68 (2)
Bi12—Br31b^ii	3.512 (5)	Bi42a—Br32a^i	2.91 (2)
Bi12—Br41a	3.78 (2)	Bi42a—Br32a	2.91 (2)
Bi12—Br41b	3.875 (14)	Bi42a—Br32b^i	3.344 (18)
Bi12—Br12	3.277 (13)	Bi42a—Br32b	3.344 (18)
Bi22—Bi22^i	4.066	Bi42a—Br42a	2.769 (12)
Bi22—Bi22^ii	4.066	Bi42a—Br42a^xii	2.769 (12)
Bi22—Bi32	3.250 (4)	Bi42b—Bi42b^i	4.066
Bi22—Bi32^ii	3.250 (4)	Bi42b—Bi42b^ii	4.066
Bi22—Ni12	2.771 (5)	Bi42b—Br22b	2.98 (3)
Bi22—Ni12^ii	2.771 (5)	Bi42b—Br32b	2.75 (2)
Bi22—Ni12^v	2.792 (9)	Bi42b—Br42a	3.436 (10)
Bi22—Br12^v	3.348 (9)	Bi42b—Br42a^ii	3.436 (10)
Bi22—Br12^vi	3.348 (9)	Bi42b—Br42a^xii	3.436 (10)
Bi22—Br22a^v	4.139 (13)	Bi42b—Br42a^xi	3.436 (10)
Bi22—Br22a^vi	4.139 (13)	Bi42b—Br42b	2.854 (7)
Bi22—Br22b^v	3.606 (12)	Bi42b—Br42b^ii	2.854 (7)
Bi22—Br22b^vi	3.606 (12)	Bi42b—Br42b^xii	2.854 (7)
Bi32—Bi32^i	4.066	Bi42b—Br42b^xi	2.854 (7)
Bi32—Bi32^ii	4.066	Br22a—Br22a^i	4.066
Bi32—Ni12	2.665 (10)	Br22a—Br22a^ii	4.066
Bi32—Br41a^i	3.465 (14)	Br22a—Br22b^i	4.169 (7)
Bi32—Br41a	3.465 (14)	Br22a—Br22b^ii	4.169 (7)
Bi32—Br41b^i	3.927 (11)	Br22a—Br42a	4.050 (16)
Bi32—Br41b	3.927 (11)	Br22a—Br42a^ii	4.050 (16)
Bi32—Br22a^v	3.817 (4)	Br22a—Br42a^xii	4.050 (16)
Bi32—Br22b^v	3.787 (4)	Br22a—Br42a^xi	4.050 (16)
Bi32—Br42a^vii	3.549 (13)	Br22a—Br42b	3.533 (16)
Bi32—Br42a^v	3.549 (13)	Br22a—Br42b^ii	3.533 (16)
Bi32—Br42b^vii	3.792 (13)	Br22a—Br42b^xii	3.533 (16)
Bi32—Br42b^v	3.792 (13)	Br22a—Br42b^xi	3.533 (16)
Ni12—Ni12^i	4.066	Br22b—Br22b^i	4.066
Ni12—Ni12^ii	4.066	Br22b—Br22b^ii	4.066
Ni12—Ni12^vii	2.505 (8)	Br22b—Br42b	4.14 (2)
Ni12—Ni12^v	2.505 (8)	Br22b—Br42b^ii	4.14 (2)
Br11—Br11^i	4.066	Br22b—Br42b^xii	4.14 (2)
Br11—Br11^ii	4.066	Br22b—Br42b^xi	4.14 (2)
Br11—Br21a	4.05 (3)	Br32a—Br32a^i	4.066
Br11—Br21b	3.51 (4)	Br32a—Br32a^ii	4.066
Br11—Br32a^ix	4.08 (3)	Br32a—Br32b^i	4.107 (5)
Br11—Br32a^x	4.08 (3)	Br32a—Br32b^ii	4.107 (5)
Br11—Br32b^ix	3.59 (2)	Br32a—Br42a	4.017 (19)
Br11—Br32b^x	3.59 (2)	Br32a—Br42a^ii	4.017 (19)
Bi41a—Bi41a^i	4.066	Br32a—Br42a^xii	4.017 (19)
Bi41a—Bi41a^ii	4.066	Br32a—Br42a^xi	4.017 (19)
Bi41a—Br21a	2.88 (2)	Br32a—Br42b	3.57 (2)
Bi41a—Br21a^ii	2.88 (2)	Br32a—Br42b^ii	3.57 (2)
Bi41a—Br21b	3.28 (3)	Br32a—Br42b^xii	3.57 (2)
Bi41a—Br21b^ii	3.28 (3)	Br32a—Br42b^xi	3.57 (2)
Bi41a—Br31a	2.926 (18)	Br32b—Br32b^i	4.066
Bi41a—Br31a^ii	2.926 (18)	Br32b—Br32b^ii	4.066
Bi41a—Br31b	3.76 (2)	Br32b—Br42b	3.944 (19)
Bi41a—Br31b^ii	3.76 (2)	Br32b—Br42b^ii	3.944 (19)
Bi41a—Br41a	2.922 (13)	Br32b—Br42b^xii	3.944 (19)
Bi41a—Br41a^xi	2.922 (13)	Br32b—Br42b^xi	3.944 (19)
Bi41b—Bi41b^i	4.066	Br42a—Br42a^i	4.066
Bi41b—Bi41b^ii	4.066	Br42a—Br42a^ii	4.066
Bi41b—Br21b	2.67 (4)	Br42a—Br42b^i	4.138 (3)
Bi41b—Br31b	3.07 (3)	Br42a—Br42b^ii	4.138 (3)
Bi41b—Br41a^i	3.559 (10)	Br42b—Br42b^i	4.066
Bi41b—Br41a	3.559 (10)	Br42b—Br42b^ii	4.066
Bi41b—Br41a^xii	3.559 (10)	Br42b—Br42b^xii	4.005 (14)
Bi41b—Br41a^xi	3.559 (10)

Symmetry codes: (i) x−1, y, z; (ii) x+1, y, z; (iii) −x+1, −y, −z+1; (iv) −x+2, −y, −z+1; (v) −x+1, −y+1, −z+1; (vi) −x+2, −y+1, −z+1; (vii) −x, −y+1, −z+1; (viii) −x, −y, −z+1; (ix) x−1, y−1, z; (x) x, y−1, z; (xi) −x+3/2, y, −z+1/2; (xii) −x+1/2, y, −z+1/2.

(Bi7Ni2Br5mod)

Crystal data

Bi6.889Br4.778Ni2	F(000) = 3183
Mr = 1938.8	Dx = 7.941 Mg m^−3
Orthorhombic, Xmnm(α00)00s†	Mo Kα radiation, λ = 0.71073 Å
q = 0.11111a*	Cell parameters from 14269 reflections
a = 4.0660 (4) Å	θ = 1.8–24.5°
b = 46.610 (5) Å	µ = 88.43 mm^−1
c = 17.1299 (15) Å	T = 293 K
V = 3246.4 (5) Å^3	Needle, black
Z = 8	0.6 × 0.08 × 0.02 mm

† Symmetry operations: (1) x₁, x₂, x₃, x₄; (2) 1/2+x₁, −x₂, 1/2+x₃, x₄; (3) x₁, x₂, 1/2−x₃, x₄; (4) 1/2+x₁, −x₂, −x₃, x₄; (5) −x₁, −x₂, −x₃, −x₄; (6) 1/2−x₁, x₂, 1/2−x₃, −x₄; (7) −x₁, −x₂, 1/2+x₃, −x₄; (8) 1/2−x₁, x₂, x₃, −x₄; (9) x₁, 1/2+x₂, x₃, 1/2+x₄; (10) 1/2+x₁, 1/2−x₂, 1/2+x₃, 1/2+x₄; (11) x₁, 1/2+x₂, 1/2−x₃, 1/2+x₄; (12) 1/2+x₁, 1/2−x₂, −x₃, 1/2+x₄; (13) −x₁, 1/2−x₂, −x₃, 1/2−x₄; (14) 1/2−x₁, 1/2+x₂, 1/2−x₃, 1/2−x₄; (15) −x₁, 1/2−x₂, 1/2+x₃, 1/2−x₄; (16) 1/2−x₁, 1/2+x₂, x₃, 1/2−x₄.

Data collection

Imaging plate diffractometer STOE IPDS II	7264 independent reflections
Radiation source: fine-focus sealed tube	2724 reflections with I > 3σ(I)
Graphite monochromator	Rint = 0.150
incremental rotation scans	θmax = 24.6°, θmin = 1.4°
Absorption correction: numerical (Jana2000; Petricek, Dusek & Palatinus, 2000)	h = −4→4
Tmin = 0.02, Tmax = 0.204	k = −54→54
84857 measured reflections	l = −20→20

Refinement

Refinement on F^2	213 parameters
R[F^2 > 2σ(F^2)] = 0.070	Weighting scheme based on measured s.u.'s w = 1/(σ^2(I) + 0.000025I^2)
wR(F^2) = 0.090	(Δ/σ)max = 0.001
S = 3.18	Δρmax = 9.13 e Å^−3
7264 reflections	Δρmin = −9.18 e Å^−3

Special details

Refinement. The starting model for the refinement of the superstructure is based on crystal chemical considerations. Due to high correlations several restraints were applied in the refinement. The fourier maps show that the electron density is described well by the proposed modulation model.

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

	x	y	z	Uiso*/Ueq
Bi11	0.75	0.03594 (3)	0.58915 (5)	0.0211 (4)
Bi21	0.75	0.02775 (3)	0.39177 (5)	0.0207 (4)
Bi31	0.25	0.07282 (4)	0.47440 (7)	0.0339 (5)
Ni11	0.25	0.01602 (11)	0.49796 (18)	0.0212 (3)
Bi12	0.75	0.21399 (3)	0.41278 (6)	0.0246 (4)
Bi22	0.75	0.22365 (4)	0.61083 (6)	0.0273 (4)
Bi32	0.25	0.17796 (4)	0.53016 (7)	0.0419 (6)
Ni12	0.25	0.23442 (11)	0.50508 (18)	0.0212 (3)
Br11	0.25	0.00132 (14)	0.25	0.0375 (19)
Bi41a	0.75	0.13189 (6)	0.25	0.0279 (9)
Bi41b	0.25	0.13428 (8)	0.25	0.0233 (15)
Br21a	0.25	0.08685 (19)	0.25	0.046 (2)
Br21b	0.25	0.0761 (3)	0.25	0.046 (2)
Br31a	0.25	0.17822 (19)	0.25	0.045 (3)
Br31b	0.25	0.1999 (2)	0.25	0.045 (3)
Br41a	0.75	0.13176 (15)	0.4127 (3)	0.0453 (16)
Br41b	0.75	0.13313 (19)	0.3729 (4)	0.0453 (16)
Br12	0.75	0.2509 (2)	0.25	0.035 (3)
Bi42a	0.25	0.38047 (7)	0.25	0.0251 (12)
Bi42b	0.75	0.37836 (7)	0.25	0.0282 (11)
Br22a	0.75	0.3349 (2)	0.25	0.0330 (19)
Br22b	0.75	0.3156 (2)	0.25	0.0330 (19)
Br32a	0.75	0.42474 (18)	0.25	0.0246 (15)
Br32b	0.75	0.43808 (19)	0.25	0.0246 (15)
Br42a	0.25	0.38159 (17)	0.4170 (3)	0.0362 (15)
Br42b	0.25	0.37878 (13)	0.3726 (3)	0.0362 (15)

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Bi11	0.0173 (8)	0.0283 (8)	0.0176 (4)	0	0	−0.0026 (5)
Bi21	0.0176 (8)	0.0314 (7)	0.0132 (4)	0	0	0.0039 (5)
Bi31	0.0432 (12)	0.0227 (8)	0.0357 (5)	0	0	0.0036 (6)
Ni11	0.0154 (6)	0.0232 (7)	0.0251 (5)	0	0	0.0009 (5)
Bi12	0.0219 (9)	0.0290 (8)	0.0229 (4)	0	0	−0.0054 (5)
Bi22	0.0208 (9)	0.0335 (9)	0.0275 (5)	0	0	0.0059 (6)
Bi32	0.0554 (15)	0.0248 (9)	0.0454 (6)	0	0	0.0044 (7)
Ni12	0.0154 (6)	0.0232 (7)	0.0251 (5)	0	0	0.0009 (5)
Br11	0.047 (4)	0.043 (4)	0.0226 (16)	0	0	0
Bi41a	0.028 (2)	0.0340 (17)	0.0214 (9)	0	0	0
Bi41b	0.026 (4)	0.0248 (19)	0.0194 (13)	0	0	0
Br21a	0.048 (5)	0.023 (4)	0.066 (3)	0	0	0
Br21b	0.048 (5)	0.023 (4)	0.066 (3)	0	0	0
Br31a	0.052 (5)	0.019 (5)	0.065 (3)	0	0	0
Br31b	0.052 (5)	0.019 (5)	0.065 (3)	0	0	0
Br41a	0.052 (3)	0.053 (3)	0.0312 (18)	0	0	0.0013 (17)
Br41b	0.052 (3)	0.053 (3)	0.0312 (18)	0	0	0.0013 (17)
Br12	0.040 (6)	0.042 (5)	0.023 (3)	0	0	0
Bi42a	0.026 (3)	0.0229 (18)	0.0267 (12)	0	0	0
Bi42b	0.031 (3)	0.0301 (16)	0.0234 (11)	0	0	0
Br22a	0.033 (3)	0.039 (4)	0.0272 (17)	0	0	0
Br22b	0.033 (3)	0.039 (4)	0.0272 (17)	0	0	0
Br32a	0.017 (3)	0.034 (3)	0.0230 (15)	0	0	0
Br32b	0.017 (3)	0.034 (3)	0.0230 (15)	0	0	0
Br42a	0.036 (3)	0.052 (3)	0.0207 (17)	0	0	0.0016 (16)
Br42b	0.036 (3)	0.052 (3)	0.0207 (17)	0	0	0.0016 (16)

(Bi7Ni2Br5simplified)

Crystal data

Bi6.889Br4.778Ni2	F(000) = 3183
Mr = 1938.8	Dx = 7.941 Mg m^−3
Orthorhombic, Cmcm	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -C -2zc;-2x	Cell parameters from 14269 reflections
a = 4.0660 (4) Å	θ = 1.8–24.5°
b = 23.305 (3) Å	µ = 88.43 mm^−1
c = 17.130 (2) Å	T = 293 K
V = 1623.2 (3) Å^3	Needle, black
Z = 4	0.6 × 0.08 × 0.02 mm

Data collection

Imaging plate diffractometer STOE IPDS II	815 independent reflections
Radiation source: fine-focus sealed tube	752 reflections with I > 3σ(I)
Graphite monochromator	Rint = 0.103
incremental rotation scans	θmax = 24.5°, θmin = 1.8°
Absorption correction: numerical microscopic crystal description optimized with X-SHAPE 1.06 (Stoe, 1999)	h = −4→4
Tmin = 0.02, Tmax = 0.204	k = −26→26
8504 measured reflections	l = −19→19

Refinement

Refinement on F^2	56 parameters
R[F^2 > 2σ(F^2)] = 0.039	Weighting scheme based on measured s.u.'s w = 1/(σ^2(I) + 0.000025I^2)
wR(F^2) = 0.078	(Δ/σ)max = 0.0004
S = 7.85	Δρmax = 2.92 e Å^−3
815 reflections	Δρmin = −3.05 e Å^−3

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

	x	y	z	Uiso*/Ueq	Occ. (<1)
Bi1	0.5	0.32190 (5)	0.41176 (5)	0.0240 (3)
Bi2	0.5	0.30445 (5)	0.60932 (5)	0.0271 (3)
Bi3	0	0.39502 (6)	0.52761 (7)	0.0417 (4)
Ni	0	0.28158 (15)	0.50355 (15)	0.0214 (9)
Br1	0.5	0.2476 (3)	0.25	0.047 (2)	0.82 (2)
Bi4a	0.5	0.48744 (16)	0.25	0.0449 (11)	0.502 (7)
Bi4b	0	0.4880 (2)	0.25	0.0449 (11)	0.381 (6)
Br2a	0	0.3945 (4)	0.25	0.048 (2)	0.732 (10)
Br2b	0	0.3585 (12)	0.25	0.048 (2)	0.268 (10)
Br3a	0	0.5804 (4)	0.25	0.051 (2)	0.732 (10)
Br3b	0	0.6156 (12)	0.25	0.051 (2)	0.268 (10)
Br4a	0.5	0.4866 (3)	0.4150 (4)	0.0456 (15)	0.5
Br4b	0.5	0.4888 (3)	0.3726 (4)	0.0456 (15)	0.5

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Bi1	0.0201 (5)	0.0309 (6)	0.0211 (4)	0	0	0.0041 (4)
Bi2	0.0194 (6)	0.0408 (7)	0.0211 (4)	0	0	−0.0068 (4)
Bi3	0.0496 (8)	0.0262 (6)	0.0493 (6)	0	0	−0.0077 (5)
Ni	0.0158 (16)	0.0222 (17)	0.0261 (13)	0	0	−0.0002 (13)
Br1	0.048 (4)	0.068 (5)	0.026 (3)	0	0	0
Bi4a	0.077 (2)	0.0353 (17)	0.0225 (13)	0	0	0
Bi4b	0.077 (2)	0.0353 (17)	0.0225 (13)	0	0	0
Br2a	0.037 (4)	0.068 (6)	0.040 (2)	0	0	0
Br2b	0.037 (4)	0.068 (6)	0.040 (2)	0	0	0
Br3a	0.047 (4)	0.060 (5)	0.046 (2)	0	0	0
Br3b	0.047 (4)	0.060 (5)	0.046 (2)	0	0	0
Br4a	0.050 (3)	0.058 (3)	0.028 (3)	0	0	−0.003 (3)
Br4b	0.050 (3)	0.058 (3)	0.028 (3)	0	0	−0.003 (3)

Bond lengths (Å)

Bi1—Bi2	3.4086 (12)	Br1—Br2a	3.980 (10)
Bi1—Bi2^i	3.5965 (13)	Br1—Br2a^iii	3.980 (10)
Bi1—Bi2^ii	3.5965 (13)	Br1—Br2b	3.29 (2)
Bi1—Bi3	3.3128 (12)	Br1—Br2b^iii	3.29 (2)
Bi1—Bi3^iii	3.3128 (12)	Br1—Br3a^viii	3.897 (12)
Bi1—Ni	2.737 (2)	Br1—Br3b^viii	3.08 (3)
Bi1—Ni^iii	2.737 (2)	Bi4a—Br2a	2.971 (8)
Bi1—Ni^i	2.814 (3)	Bi4a—Br2a^iii	2.971 (8)
Bi1—Br1	3.267 (4)	Bi4a—Br2b	3.63 (2)
Bi1—Br2a	3.830 (4)	Bi4a—Br2b^iii	3.63 (2)
Bi1—Br2a^iii	3.830 (4)	Bi4a—Br3a	2.971 (7)
Bi1—Br2b	3.541 (7)	Bi4a—Br3a^iii	2.971 (7)
Bi1—Br2b^iii	3.541 (7)	Bi4a—Br3b	3.61 (2)
Bi1—Br4a	3.839 (8)	Bi4a—Br3b^iii	3.61 (2)
Bi1—Br4b	3.946 (8)	Bi4a—Br4a	2.826 (7)
Bi2—Bi3	3.2477 (13)	Bi4a—Br4a^ix	2.826 (7)
Bi2—Bi3^iii	3.2477 (13)	Bi4b—Br2b	3.02 (3)
Bi2—Ni	2.7749 (19)	Bi4b—Br3b	2.97 (3)
Bi2—Ni^iii	2.7749 (19)	Bi4b—Br4a^vi	3.481 (5)
Bi2—Ni^i	2.785 (3)	Bi4b—Br4a	3.481 (5)
Bi2—Br1^i	3.378 (3)	Bi4b—Br4a^x	3.481 (5)
Bi2—Br1^ii	3.378 (3)	Bi4b—Br4a^ix	3.481 (5)
Bi2—Br3b^iv	3.663 (14)	Bi4b—Br4b^vi	2.923 (5)
Bi2—Br3b^v	3.663 (14)	Bi4b—Br4b	2.923 (5)
Bi3—Ni	2.676 (4)	Bi4b—Br4b^x	2.923 (5)
Bi3—Br3a^iv	3.8525 (18)	Bi4b—Br4b^ix	2.923 (5)
Bi3—Br3b^iv	3.818 (2)	Br2a—Br4b^vi	3.657 (8)
Bi3—Br4a^vi	3.523 (6)	Br2a—Br4b	3.657 (8)
Bi3—Br4a	3.523 (6)	Br2a—Br4b^x	3.657 (8)
Bi3—Br4a^iv	3.565 (6)	Br2a—Br4b^ix	3.657 (8)
Bi3—Br4a^v	3.565 (6)	Br3a—Br4b^vi	3.620 (8)
Bi3—Br4b^vi	3.994 (6)	Br3a—Br4b	3.620 (8)
Bi3—Br4b	3.994 (6)	Br3a—Br4b^x	3.620 (8)
Bi3—Br4b^iv	3.794 (6)	Br3a—Br4b^ix	3.620 (8)
Bi3—Br4b^v	3.794 (6)	Br4a—Br4a^v	2.979 (9)
Ni—Ni^vii	2.513 (3)	Br4a—Br4b^v	3.684 (9)
Ni—Ni^i	2.513 (3)

Symmetry codes: (i) −x+1/2, −y+1/2, −z+1; (ii) −x+3/2, −y+1/2, −z+1; (iii) x+1, y, z; (iv) −x, −y+1, −z+1; (v) −x+1, −y+1, −z+1; (vi) x−1, y, z; (vii) −x−1/2, −y+1/2, −z+1; (viii) x+1/2, y−1/2, z; (ix) x, y, −z+1/2; (x) x−1, y, −z+1/2.