Supporting information
Crystallographic Information File (CIF) https://doi.org/10.1107/S0108270105007493/sq1196sup1.cif | |
Structure factor file (CIF format) https://doi.org/10.1107/S0108270105007493/sq1196Isup2.hkl |
Single crystals of Ag3.5Bi7.5S13 were obtained as a by-product of a solid-state reaction involving AgI and Bi2S3 in the molar ratio 1:1. The mixture of the starting materials was thoroughly ground and loaded into a silica tube, which was flame-sealed under a pressure of 10 −2 Torr (1 Torr = 133.322 Pa). The tube was placed in a tubular oven, heated at 850 K for 7 d and then rapidly cooled to room temperature. The product consisted of a mixture of black plate crystals of AgBiS2 (Geller & Wernick, 1959), Ag2Bi6S10 (Makovicky et al., 1977) and Ag3.5Bi7.5S13 (about 30% of the product), together with grey needle-like crystals of (Bi2S3)9BiI3 (Miehe & Kup~cik, 1971). Qualitative energy-dispersive X-ray analysis performed on the single-crystal of Ag3.5Bi7.5S13 used for this study revealed an average composition Ag3.43 (2)Bi7.48 (2)S13. No indication of iodine in the crystal was detected.
In the first stage of the refinement, the Bi positions M3, M4 and M6 showed temperature factors larger than that of M1 = Bi1. This suggested that, in addition to bismuth, these positions are partly occupied by the lighter element Ag. On the other hand, the thermal parameters of the Ag positions M2 and M5 were smaller than that of Bi1 and mixed occupancy with the heavier element Bi was also considered for these positions. The SUMP restraint was used to ensure the electroneutrality of the compound. The final occupancies of these positions obtained from the refinement were: M2 = 79% Ag + 21% Bi, M3 = 22% Ag + 78% Bi, M4 = 16% Ag + 84% Bi, M5 = 64% Ag + 36% Bi and M6 = 33% Ag + 67% Bi.
Data collection: EXPOSE (Stoe & Cie, 2000); cell refinement: CELL (Stoe & Cie, 2000); data reduction: INTEGRATE (Stoe & Cie, 2000); program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: DIAMOND (Brandenburg, 1999); software used to prepare material for publication: SHELXL97 and DIAMOND.
Ag3.5Bi7.5S13 | F(000) = 1990 |
Mr = 2361.81 | Dx = 6.782 Mg m−3 |
Monoclinic, C2/m | Mo Kα radiation, λ = 0.71073 Å |
Hall symbol: -C2y | Cell parameters from 1295 reflections |
a = 13.3237 (2) Å | θ = 2.9–26.0° |
b = 4.0455 (4) Å | µ = 60.9 mm−1 |
c = 21.484 (3) Å | T = 297 K |
β = 92.90 (1)° | Plate, black |
V = 1156.5 (2) Å3 | 0.14 × 0.04 × 0.02 mm |
Z = 2 |
Stoe IPDS I diffractometer | 1295 independent reflections |
Radiation source: fine-focus sealed tube | 980 reflections with I > 2σ(I) |
Graphite monochromator | Rint = 0.040 |
ϕ oscillation scans | θmax = 26.0°, θmin = 2.9° |
Absorption correction: numerical [X-RED32 (Stoe & Cie, 2001); crystal description using FACEIT (Stoe & Cie, 1999), optimization using equivalent reflections (X-SHAPE; Stoe & Cie, 1999)] | h = −16→16 |
Tmin = 0.067, Tmax = 0.343 | k = −4→4 |
3944 measured reflections | l = −26→26 |
Refinement on F2 | Primary atom site location: structure-invariant direct methods |
Least-squares matrix: full | Secondary atom site location: difference Fourier map |
R[F2 > 2σ(F2)] = 0.044 | w = 1/[σ2(Fo2) + (0.041P)2 + 88.7342P] where P = (Fo2 + 2Fc2)/3 |
wR(F2) = 0.104 | (Δ/σ)max = 0.009 |
S = 1.07 | Δρmax = 1.90 e Å−3 |
1295 reflections | Δρmin = −1.47 e Å−3 |
81 parameters | Extinction correction: SHELXL97, Fc*=kFc[1+0.001xFc2λ3/sin(2θ)]-1/4 |
1 restraint | Extinction coefficient: 0.00038 (6) |
Ag3.5Bi7.5S13 | V = 1156.5 (2) Å3 |
Mr = 2361.81 | Z = 2 |
Monoclinic, C2/m | Mo Kα radiation |
a = 13.3237 (2) Å | µ = 60.9 mm−1 |
b = 4.0455 (4) Å | T = 297 K |
c = 21.484 (3) Å | 0.14 × 0.04 × 0.02 mm |
β = 92.90 (1)° |
Stoe IPDS I diffractometer | 1295 independent reflections |
Absorption correction: numerical [X-RED32 (Stoe & Cie, 2001); crystal description using FACEIT (Stoe & Cie, 1999), optimization using equivalent reflections (X-SHAPE; Stoe & Cie, 1999)] | 980 reflections with I > 2σ(I) |
Tmin = 0.067, Tmax = 0.343 | Rint = 0.040 |
3944 measured reflections |
R[F2 > 2σ(F2)] = 0.044 | 1 restraint |
wR(F2) = 0.104 | w = 1/[σ2(Fo2) + (0.041P)2 + 88.7342P] where P = (Fo2 + 2Fc2)/3 |
S = 1.07 | Δρmax = 1.90 e Å−3 |
1295 reflections | Δρmin = −1.47 e Å−3 |
81 parameters |
Experimental. collection of intensity data: phi movement mode (oscillation), crystal to detector distance (70 mm), lattice parameters from Stoe IPDS-I diffraction data using Mo Kα radiation |
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. A disorder model M = Bi, Ag was applied for the atomic sites M2, M3, M4, M5 and M6 that were constrained to full occupation. In each mixed position both types of atoms were forced to have the same coordinates and thermal parameters. The mixed occupation in cation positions were restrained to keep the electroneutrality of the compound. 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. |
x | y | z | Uiso*/Ueq | Occ. (<1) | |
Bi1 | 0.23594 (6) | 0.0000 | 0.08464 (4) | 0.0322 (3) | |
Bi2 | 0.5000 | 0.0000 | 0.0000 | 0.0458 (7) | 0.2022 (10) |
Ag2 | 0.5000 | 0.0000 | 0.0000 | 0.0458 (7) | 0.80 |
Bi3 | 0.01767 (7) | 0.5000 | 0.21444 (5) | 0.0313 (4) | 0.777 (4) |
Ag3 | 0.01767 (7) | 0.5000 | 0.21444 (5) | 0.0313 (4) | 0.22 |
Bi4 | 0.30067 (6) | 0.5000 | 0.29459 (5) | 0.0292 (4) | 0.844 (4) |
Ag4 | 0.30067 (6) | 0.5000 | 0.29459 (5) | 0.0292 (4) | 0.16 |
Bi5 | 0.08218 (9) | 0.0000 | 0.37761 (7) | 0.0374 (6) | 0.358 (4) |
Ag5 | 0.08218 (9) | 0.0000 | 0.37761 (7) | 0.0374 (6) | 0.64 |
Bi6 | 0.36005 (7) | 0.0000 | 0.46000 (5) | 0.0323 (4) | 0.670 (4) |
Ag6 | 0.36005 (7) | 0.0000 | 0.46000 (5) | 0.0323 (4) | 0.33 |
S1 | 0.3550 (4) | 0.5000 | 0.0257 (3) | 0.0227 (11) | |
S2 | 0.0975 (4) | 0.5000 | 0.1060 (3) | 0.0301 (13) | |
S3 | 0.3801 (4) | 0.5000 | 0.1850 (3) | 0.0241 (12) | |
S4 | 0.1612 (4) | 0.0000 | 0.2616 (3) | 0.0323 (14) | |
S5 | 0.4389 (4) | 0.0000 | 0.3418 (3) | 0.0298 (13) | |
S6 | 0.2184 (4) | 0.5000 | 0.4222 (3) | 0.0332 (14) | |
S7 | 0.5000 | 0.5000 | 0.5000 | 0.039 (2) |
U11 | U22 | U33 | U12 | U13 | U23 | |
Bi1 | 0.0322 (5) | 0.0330 (6) | 0.0311 (6) | 0.000 | −0.0018 (3) | 0.000 |
Bi2 | 0.0356 (11) | 0.0460 (16) | 0.0551 (16) | 0.000 | −0.0037 (10) | 0.000 |
Ag2 | 0.0356 (11) | 0.0460 (16) | 0.0551 (16) | 0.000 | −0.0037 (10) | 0.000 |
Bi3 | 0.0331 (6) | 0.0303 (7) | 0.0310 (7) | 0.000 | 0.0051 (4) | 0.000 |
Ag3 | 0.0331 (6) | 0.0303 (7) | 0.0310 (7) | 0.000 | 0.0051 (4) | 0.000 |
Bi4 | 0.0273 (5) | 0.0275 (6) | 0.0331 (6) | 0.000 | 0.0048 (4) | 0.000 |
Ag4 | 0.0273 (5) | 0.0275 (6) | 0.0331 (6) | 0.000 | 0.0048 (4) | 0.000 |
Bi5 | 0.0331 (8) | 0.0346 (10) | 0.0444 (10) | 0.000 | −0.0005 (6) | 0.000 |
Ag5 | 0.0331 (8) | 0.0346 (10) | 0.0444 (10) | 0.000 | −0.0005 (6) | 0.000 |
Bi6 | 0.0328 (7) | 0.0309 (7) | 0.0334 (7) | 0.000 | 0.0047 (5) | 0.000 |
Ag6 | 0.0328 (7) | 0.0309 (7) | 0.0334 (7) | 0.000 | 0.0047 (5) | 0.000 |
S1 | 0.019 (2) | 0.021 (3) | 0.029 (3) | 0.000 | 0.0056 (19) | 0.000 |
S2 | 0.031 (3) | 0.023 (3) | 0.037 (3) | 0.000 | 0.008 (2) | 0.000 |
S3 | 0.020 (2) | 0.024 (3) | 0.028 (3) | 0.000 | −0.001 (2) | 0.000 |
S4 | 0.026 (3) | 0.023 (3) | 0.046 (4) | 0.000 | −0.008 (3) | 0.000 |
S5 | 0.030 (3) | 0.028 (3) | 0.032 (3) | 0.000 | 0.005 (2) | 0.000 |
S6 | 0.029 (3) | 0.033 (4) | 0.037 (4) | 0.000 | 0.000 (2) | 0.000 |
S7 | 0.030 (4) | 0.029 (5) | 0.056 (6) | 0.000 | −0.016 (4) | 0.000 |
Bi1—S1i | 2.608 (6) | Bi6—S5 | 2.797 (6) |
Bi1—S2ii | 2.791 (4) | Bi6—S7 | 2.8539 (7) |
Bi1—S2 | 2.791 (4) | Bi6—S7ii | 2.8539 (7) |
Bi1—S1 | 2.900 (4) | Bi6—S6ii | 2.856 (4) |
Bi1—S1ii | 2.900 (4) | Bi6—S6 | 2.856 (4) |
Bi1—S3 | 3.465 (4) | S1—Bi1i | 2.608 (6) |
Bi1—S3ii | 3.465 (4) | S1—Bi2viii | 2.871 (3) |
Bi2—S2iii | 2.565 (6) | S1—Bi1viii | 2.900 (4) |
Bi2—S2i | 2.565 (6) | S1—S3 | 3.420 (8) |
Bi2—S1ii | 2.871 (3) | S1—S2i | 3.562 (7) |
Bi2—S1 | 2.871 (3) | S1—S2x | 3.562 (7) |
Bi2—S1iv | 2.871 (3) | S2—Bi2vii | 2.565 (6) |
Bi2—S1v | 2.871 (3) | S2—Bi1viii | 2.791 (4) |
Bi3—S2 | 2.609 (6) | S2—S1i | 3.562 (7) |
Bi3—S3vi | 2.781 (3) | S2—S1x | 3.562 (7) |
Bi3—S3vii | 2.781 (3) | S3—Bi3xi | 2.781 (3) |
Bi3—S4viii | 2.929 (4) | S3—Bi3iii | 2.781 (3) |
Bi3—S4 | 2.929 (4) | S3—Bi1viii | 3.465 (4) |
Bi3—S5vii | 2.979 (6) | S4—Bi4ii | 2.813 (4) |
Bi4—S3 | 2.630 (6) | S4—Bi3ii | 2.929 (4) |
Bi4—S4 | 2.813 (4) | S5—Bi5xi | 2.860 (4) |
Bi4—S4viii | 2.813 (4) | S5—Bi5iii | 2.860 (4) |
Bi4—S5viii | 2.885 (4) | S5—Bi4ii | 2.885 (4) |
Bi4—S5 | 2.885 (4) | S5—Bi3iii | 2.979 (6) |
Bi4—S6 | 3.002 (6) | S6—Bi6ix | 2.788 (6) |
Bi5—S4 | 2.753 (7) | S6—Bi5viii | 2.851 (4) |
Bi5—S6 | 2.851 (4) | S6—Bi6viii | 2.856 (4) |
Bi5—S6ii | 2.851 (4) | S7—Bi6xii | 2.8539 (8) |
Bi5—S5vi | 2.860 (4) | S7—Bi6xiii | 2.8539 (7) |
Bi5—S5vii | 2.860 (4) | S7—Bi6viii | 2.8539 (7) |
Bi5—S7vi | 2.8990 (16) | S7—Bi5ix | 2.8990 (16) |
Bi6—S6ix | 2.788 (6) | S7—Bi5xi | 2.8990 (16) |
S1i—Bi1—S2ii | 82.50 (15) | Bi1viii—S1—Bi1 | 88.46 (14) |
S1i—Bi1—S2 | 82.50 (15) | Bi1i—S1—S3 | 157.97 (19) |
S2ii—Bi1—S2 | 92.88 (16) | Bi2viii—S1—S3 | 99.20 (14) |
S1i—Bi1—S1 | 80.93 (13) | Bi2—S1—S3 | 99.20 (14) |
S2ii—Bi1—S1 | 163.30 (17) | Bi1viii—S1—S3 | 65.90 (11) |
S2—Bi1—S1 | 86.96 (11) | Bi1—S1—S3 | 65.90 (11) |
S1i—Bi1—S1ii | 80.93 (13) | Bi1i—S1—S2i | 50.97 (12) |
S2ii—Bi1—S1ii | 86.96 (11) | Bi2viii—S1—S2i | 95.65 (15) |
S2—Bi1—S1ii | 163.30 (17) | Bi2—S1—S2i | 45.43 (10) |
S1—Bi1—S1ii | 88.46 (14) | Bi1viii—S1—S2i | 150.0 (2) |
S1i—Bi1—S3 | 141.53 (7) | Bi1—S1—S2i | 94.23 (8) |
S2ii—Bi1—S3 | 132.12 (16) | S3—S1—S2i | 141.50 (11) |
S2—Bi1—S3 | 79.90 (12) | Bi1i—S1—S2x | 50.97 (12) |
S1—Bi1—S3 | 64.28 (13) | Bi2viii—S1—S2x | 45.43 (10) |
S1ii—Bi1—S3 | 112.36 (12) | Bi2—S1—S2x | 95.65 (15) |
S1i—Bi1—S3ii | 141.53 (7) | Bi1viii—S1—S2x | 94.23 (8) |
S2ii—Bi1—S3ii | 79.90 (12) | Bi1—S1—S2x | 150.0 (2) |
S2—Bi1—S3ii | 132.12 (16) | S3—S1—S2x | 141.50 (11) |
S1—Bi1—S3ii | 112.36 (12) | S2i—S1—S2x | 69.19 (15) |
S1ii—Bi1—S3ii | 64.28 (13) | Bi2vii—S2—Bi3 | 125.6 (2) |
S3—Bi1—S3ii | 71.44 (10) | Bi2vii—S2—Bi1viii | 99.37 (17) |
S2iii—Bi2—S2i | 180.00 (14) | Bi3—S2—Bi1viii | 116.73 (17) |
S2iii—Bi2—S1ii | 98.31 (14) | Bi2vii—S2—Bi1 | 99.37 (17) |
S2i—Bi2—S1ii | 81.69 (14) | Bi3—S2—Bi1 | 116.73 (17) |
S2iii—Bi2—S1 | 98.31 (14) | Bi1viii—S2—Bi1 | 92.88 (16) |
S2i—Bi2—S1 | 81.69 (14) | Bi2vii—S2—S1i | 52.88 (12) |
S1ii—Bi2—S1 | 89.60 (13) | Bi3—S2—S1i | 143.75 (9) |
S2iii—Bi2—S1iv | 81.69 (14) | Bi1viii—S2—S1i | 97.75 (17) |
S2i—Bi2—S1iv | 98.31 (14) | Bi1—S2—S1i | 46.53 (10) |
S1ii—Bi2—S1iv | 180.0 (2) | Bi2vii—S2—S1x | 52.88 (12) |
S1—Bi2—S1iv | 90.40 (13) | Bi3—S2—S1x | 143.75 (9) |
S2iii—Bi2—S1v | 81.69 (14) | Bi1viii—S2—S1x | 46.53 (10) |
S2i—Bi2—S1v | 98.31 (14) | Bi1—S2—S1x | 97.75 (17) |
S1ii—Bi2—S1v | 90.40 (13) | S1i—S2—S1x | 69.19 (15) |
S1—Bi2—S1v | 180.0 (2) | Bi4—S3—Bi3xi | 94.96 (15) |
S1iv—Bi2—S1v | 89.60 (13) | Bi4—S3—Bi3iii | 94.96 (15) |
S2—Bi3—S3vi | 95.19 (15) | Bi3xi—S3—Bi3iii | 93.31 (15) |
S2—Bi3—S3vii | 95.19 (15) | Bi4—S3—S1 | 150.71 (19) |
S3vi—Bi3—S3vii | 93.31 (15) | Bi3xi—S3—S1 | 104.94 (14) |
S2—Bi3—S4viii | 91.17 (16) | Bi3iii—S3—S1 | 104.94 (14) |
S3vi—Bi3—S4viii | 172.87 (18) | Bi4—S3—Bi1 | 108.76 (13) |
S3vii—Bi3—S4viii | 89.30 (10) | Bi3xi—S3—Bi1 | 154.74 (19) |
S2—Bi3—S4 | 91.17 (16) | Bi3iii—S3—Bi1 | 93.17 (6) |
S3vi—Bi3—S4 | 89.30 (10) | S1—S3—Bi1 | 49.82 (9) |
S3vii—Bi3—S4 | 172.87 (18) | Bi4—S3—Bi1viii | 108.76 (13) |
S4viii—Bi3—S4 | 87.36 (15) | Bi3xi—S3—Bi1viii | 93.17 (6) |
S2—Bi3—S5vii | 176.57 (18) | Bi3iii—S3—Bi1viii | 154.74 (19) |
S3vi—Bi3—S5vii | 87.16 (14) | S1—S3—Bi1viii | 49.82 (9) |
S3vii—Bi3—S5vii | 87.16 (14) | Bi1—S3—Bi1viii | 71.44 (10) |
S4viii—Bi3—S5vii | 86.34 (15) | Bi5—S4—Bi4 | 92.87 (16) |
S4—Bi3—S5vii | 86.34 (15) | Bi5—S4—Bi4ii | 92.87 (16) |
S3—Bi4—S4 | 93.73 (16) | Bi4—S4—Bi4ii | 91.94 (15) |
S3—Bi4—S4viii | 93.73 (16) | Bi5—S4—Bi3ii | 92.32 (15) |
S4—Bi4—S4viii | 91.94 (15) | Bi4—S4—Bi3ii | 174.3 (3) |
S3—Bi4—S5viii | 92.07 (14) | Bi4ii—S4—Bi3ii | 90.11 (2) |
S4—Bi4—S5viii | 174.00 (19) | Bi5—S4—Bi3 | 92.32 (15) |
S4viii—Bi4—S5viii | 89.22 (10) | Bi4—S4—Bi3 | 90.11 (2) |
S3—Bi4—S5 | 92.07 (14) | Bi4ii—S4—Bi3 | 174.3 (3) |
S4—Bi4—S5 | 89.22 (10) | Bi3ii—S4—Bi3 | 87.36 (15) |
S4viii—Bi4—S5 | 174.00 (19) | Bi6—S5—Bi5xi | 91.83 (15) |
S5viii—Bi4—S5 | 89.03 (16) | Bi6—S5—Bi5iii | 91.83 (15) |
S3—Bi4—S6 | 177.69 (16) | Bi5xi—S5—Bi5iii | 90.03 (16) |
S4—Bi4—S6 | 87.87 (16) | Bi6—S5—Bi4ii | 93.24 (14) |
S4viii—Bi4—S6 | 87.87 (16) | Bi5xi—S5—Bi4ii | 174.9 (2) |
S5viii—Bi4—S6 | 86.29 (14) | Bi5iii—S5—Bi4ii | 90.24 (3) |
S5—Bi4—S6 | 86.29 (14) | Bi6—S5—Bi4 | 93.24 (14) |
S4—Bi5—S6 | 92.16 (15) | Bi5xi—S5—Bi4 | 90.24 (3) |
S4—Bi5—S6ii | 92.16 (15) | Bi5iii—S5—Bi4 | 174.9 (2) |
S6—Bi5—S6ii | 90.39 (16) | Bi4ii—S5—Bi4 | 89.03 (15) |
S4—Bi5—S5vi | 92.11 (14) | Bi6—S5—Bi3iii | 178.6 (2) |
S6—Bi5—S5vi | 175.72 (19) | Bi5xi—S5—Bi3iii | 89.19 (14) |
S6ii—Bi5—S5vi | 89.63 (11) | Bi5iii—S5—Bi3iii | 89.19 (14) |
S4—Bi5—S5vii | 92.11 (14) | Bi4ii—S5—Bi3iii | 85.73 (14) |
S6—Bi5—S5vii | 89.63 (11) | Bi4—S5—Bi3iii | 85.73 (14) |
S6ii—Bi5—S5vii | 175.72 (19) | Bi6ix—S6—Bi5 | 92.47 (15) |
S5vi—Bi5—S5vii | 90.03 (16) | Bi6ix—S6—Bi5viii | 92.47 (15) |
S4—Bi5—S7vi | 179.72 (12) | Bi5—S6—Bi5viii | 90.39 (16) |
S6—Bi5—S7vi | 87.64 (13) | Bi6ix—S6—Bi6viii | 90.82 (16) |
S6ii—Bi5—S7vi | 87.64 (13) | Bi5—S6—Bi6viii | 176.7 (3) |
S5vi—Bi5—S7vi | 88.08 (12) | Bi5viii—S6—Bi6viii | 89.62 (3) |
S5vii—Bi5—S7vi | 88.08 (12) | Bi6ix—S6—Bi6 | 90.82 (16) |
S6ix—Bi6—S5 | 179.97 (16) | Bi5—S6—Bi6 | 89.62 (3) |
S6ix—Bi6—S7 | 89.77 (8) | Bi5viii—S6—Bi6 | 176.7 (3) |
S5—Bi6—S7 | 90.21 (8) | Bi6viii—S6—Bi6 | 90.18 (16) |
S6ix—Bi6—S7ii | 89.77 (8) | Bi6ix—S6—Bi4 | 179.4 (2) |
S5—Bi6—S7ii | 90.21 (8) | Bi5—S6—Bi4 | 87.09 (15) |
S7—Bi6—S7ii | 90.27 (3) | Bi5viii—S6—Bi4 | 87.09 (15) |
S6ix—Bi6—S6ii | 89.18 (16) | Bi6viii—S6—Bi4 | 89.63 (14) |
S5—Bi6—S6ii | 90.84 (15) | Bi6—S6—Bi4 | 89.63 (14) |
S7—Bi6—S6ii | 178.95 (13) | Bi6xii—S7—Bi6 | 180.0 |
S7ii—Bi6—S6ii | 89.77 (8) | Bi6xii—S7—Bi6xiii | 90.27 (3) |
S6ix—Bi6—S6 | 89.18 (16) | Bi6—S7—Bi6xiii | 89.73 (3) |
S5—Bi6—S6 | 90.84 (15) | Bi6xii—S7—Bi6viii | 89.73 (3) |
S7—Bi6—S6 | 89.77 (8) | Bi6—S7—Bi6viii | 90.27 (3) |
S7ii—Bi6—S6 | 178.95 (13) | Bi6xiii—S7—Bi6viii | 180.00 (4) |
S6ii—Bi6—S6 | 90.18 (16) | Bi6xii—S7—Bi5ix | 89.88 (3) |
Bi1i—S1—Bi2viii | 96.37 (14) | Bi6—S7—Bi5ix | 90.12 (3) |
Bi1i—S1—Bi2 | 96.37 (14) | Bi6xiii—S7—Bi5ix | 89.88 (3) |
Bi2viii—S1—Bi2 | 89.60 (13) | Bi6viii—S7—Bi5ix | 90.12 (3) |
Bi1i—S1—Bi1viii | 99.07 (13) | Bi6xii—S7—Bi5xi | 90.12 (3) |
Bi2viii—S1—Bi1viii | 88.90 (3) | Bi6—S7—Bi5xi | 89.88 (3) |
Bi2—S1—Bi1viii | 164.6 (2) | Bi6xiii—S7—Bi5xi | 90.12 (3) |
Bi1i—S1—Bi1 | 99.07 (13) | Bi6viii—S7—Bi5xi | 89.88 (3) |
Bi2viii—S1—Bi1 | 164.6 (2) | Bi5ix—S7—Bi5xi | 180.0 |
Bi2—S1—Bi1 | 88.90 (3) |
Symmetry codes: (i) −x+1/2, −y+1/2, −z; (ii) x, y−1, z; (iii) x+1/2, y−1/2, z; (iv) −x+1, −y+1, −z; (v) −x+1, −y, −z; (vi) x−1/2, y−1/2, z; (vii) x−1/2, y+1/2, z; (viii) x, y+1, z; (ix) −x+1/2, −y+1/2, −z+1; (x) −x+1/2, −y+3/2, −z; (xi) x+1/2, y+1/2, z; (xii) −x+1, −y+1, −z+1; (xiii) −x+1, −y, −z+1. |
Experimental details
Crystal data | |
Chemical formula | Ag3.5Bi7.5S13 |
Mr | 2361.81 |
Crystal system, space group | Monoclinic, C2/m |
Temperature (K) | 297 |
a, b, c (Å) | 13.3237 (2), 4.0455 (4), 21.484 (3) |
β (°) | 92.90 (1) |
V (Å3) | 1156.5 (2) |
Z | 2 |
Radiation type | Mo Kα |
µ (mm−1) | 60.9 |
Crystal size (mm) | 0.14 × 0.04 × 0.02 |
Data collection | |
Diffractometer | Stoe IPDS I diffractometer |
Absorption correction | Numerical [X-RED32 (Stoe & Cie, 2001); crystal description using FACEIT (Stoe & Cie, 1999), optimization using equivalent reflections (X-SHAPE; Stoe & Cie, 1999)] |
Tmin, Tmax | 0.067, 0.343 |
No. of measured, independent and observed [I > 2σ(I)] reflections | 3944, 1295, 980 |
Rint | 0.040 |
(sin θ/λ)max (Å−1) | 0.616 |
Refinement | |
R[F2 > 2σ(F2)], wR(F2), S | 0.044, 0.104, 1.07 |
No. of reflections | 1295 |
No. of parameters | 81 |
No. of restraints | 1 |
w = 1/[σ2(Fo2) + (0.041P)2 + 88.7342P] where P = (Fo2 + 2Fc2)/3 | |
Δρmax, Δρmin (e Å−3) | 1.90, −1.47 |
Computer programs: EXPOSE (Stoe & Cie, 2000), CELL (Stoe & Cie, 2000), INTEGRATE (Stoe & Cie, 2000), SHELXS97 (Sheldrick, 1997), SHELXL97 (Sheldrick, 1997), DIAMOND (Brandenburg, 1999), SHELXL97 and DIAMOND.
Bi1—S1i | 2.607 (3) | M4—S5 | 2.885 (2) |
Bi1—S2 | 2.791 (7) | M4—S6 | 3.004 (2) |
Bi1—S1 | 2.901 (2) | ||
Bi1—S3 | 3.466 (3) | M5—S4 | 2.754 (2) |
M5—S6 | 2.851 (2) | ||
M2—S2i | 2.564 (3) | M5—S5ii | 2.860 (1) |
M2—S1 | 2.870 (8) | M5—S7ii | 2.899 (2) |
M3—S2 | 2.610 (2) | M6—S6iv | 2.787 (2) |
M3—S3ii | 2.781 (8) | M6—S5 | 2.797 (2) |
M3—S4 | 2.929 (2) | M6—S7 | 2.854 (10) |
M3—S5iii | 2.980 (2) | M6—S6 | 2.856 (10) |
M4—S3 | 2.630 (2) | ||
M4—S4 | 2.813 (9) |
Symmetry codes: (i) 1/2 − x, 1/2 − y, −z; (ii) −1/2 + x, −1/2 + y, z; (iii) −1/2 + x, 1/2 + y, z; (iv) 1/2 − x, 1/2 − y, 1 − z. |
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Current knowledge of ternary sulfides with silver and bismuth is somewhat incomplete. Only the existence of AgBiS2 (Geller & Wernick, 1959), `AgBi6S9' (N = 4; Mumme, 1990), Ag2Bi6S10 (N = 5; Makovicky et al., 1977) and Ag3Bi7S12 (N = 7; Herbert & Mumme, 1981) have been reported to date. All these phases lie on the Ag2S–Bi2S3 pseudo-binary section in the ternary Ag–Bi–S system. The three latter compounds crystallize in the monoclinic space group C2/m and adopt structures that are closely related to each other. Their structures are built up of two alternating kinds of layered modules, denoted A and B. Module A is composed of double chains of monocapped trigonal prisms around Bi atoms, which alternate in the [100] direction with octahedrally coordinated metal atoms (M = Ag or Bi). Module B represents NaCl-like fragments of varying thickness defined by the parameter N, which corresponds to the number of octahedra within the chain of edge-sharing octahedra that runs diagonally across the module (Fig. 1). The structures of the above-mentioned phases with N = 4, 5 and 7 belong to the homologous series [Bi2S3]2·[AgBiS2](N-1)/2 (pavonite series), denoted by NP (Makovicky et al., 1977). Known and hypothetical members of the series can be derived from the first member, Ag0.5Bi4.5S7 (N = 2), by successive additions of (AgBiS2)0.5 equivalents to the NaCl-like module B, AgBiS2 being the end member with N = ∞.
The title compound, Ag3.5Bi7.5S13, represents the member with N = 8 of the homologous series [Bi2S3]2·[AgBiS2](N-1)/2. It crystallizes in the monoclinic space group C2/m and is isotypic with Cu1.34Ag2.38Pb1.44Bi6.28S13 (Mumme, 1990). Its structure is built up according to the principle described above. The NaCl-type module B is, in this case, eight octahedra thick (Fig. 2). Therefore, Ag3.5Bi7.5S13 can be denoted by the symbol 8P, according to the nomenclature of pavonite homologues.
Atom Bi1 displays a slightly distorted monocapped trigonal prismatic coordination of S atoms (Table 1). The cations M2 to M6 exhibit octahedral environments with varying degrees of distortion. The `octahedron' around M2 is the most distorted, with two short bonds [2.564 (3) Å] in trans positions and four elongated bonds [2.870 (8) Å] in the equatorial plane. This type of distortion towards a linear coordination ([2 + 4] geometry) is commonly observed for Ag atoms in the structures of multinary silver-containing bismuth chalcogenides. Typical examples are various members of the pavonite homologous series. The octahedra around the M3 and M4 positions are distorted towards [1 + 2+2 + 1] geometry, with short bonds trans to long bonds. Similar coordination environments are usually observed for Bi atoms in many multinary bismuth sulphosalts. The M5 and M6 positions display more regular octahedral environments, with bond distances ranging between 2.754 (2) and 2.899 (2) Å.
All octahedral metal positions show mixed occupancy between Ag and Bi. The composition of each position obtained from the refinement is consistent with the above analysis of the distortion of their coordination polyhedra. The M2 position shows a preference for Ag atoms (79%), while the M3 and M4 positions are predominantly occupied by Bi atoms (78% for M3 and 84% for M4). In the M5 position, Ag dominates. while in M6 more Bi is found. The Ag/Bi disorder generally observed in octahedrally coordinated metal positions in the structures of pavonite homologues can be related to their general formula. For odd members (N = 5 and 7), an ordered distribution of Ag and Bi between the metal positions may be envisaged, while for even members (N = 4 and 8), some octahedral positions will be necessarily of mixed occupancy or a superstructure must be established.