inorganic compounds
Cd4As2Br3
aUniversité Houari-Boumedienne, Faculté de Chimie, Laboratoire Sciences des Matériaux, BP 32 El-Alia Bab-Ezzouar, Algeria, bCentre de Diffractométrie X, Sciences Chimiques de Rennes, UMR 6226 CNRS Université de Rennes 1, Campus de Beaulieu, Avenue du Général Leclerc, France, and cDepartomento Inorgánica, Facultad C.C. Químicas, Universidad Complutense, 28040 Madrid, Spain
*Correspondence e-mail: mkarsdz@yahoo.fr
Single crystals of Cd4As2Br3 (tetracadmium biarsenide tribromide) were grown by a chemical transport reaction. The structure is isotypic with the members of the cadmium and mercury pnictidohalides family with general formula M4A2X3 (M = Cd, Hg; A = P, As, Sb; X = Cl, Br, I) and contains two independent As atoms on special positions with -3 and two independent Cd atoms, of which one is on a special position with -3. The Cd4As2Br3 structure consists of AsCd4 tetrahedra sharing vertices with isolated As2Cd6 octahedra that contain As–As dumbbells in the centre of the octahedron. The Br atoms are located in the voids of this three-dimensional arrangement and bridge the different polyhedra through Cd⋯Br contacts.
CCDC reference: 988028
Related literature
For structural data of the title compound extracted from X-ray powder diffraction data, see: Suchow & Stemple (1963); Rebbah & Deschanvres (1981). For classification and bond character of cadmium and mercury pnictidohalides, see: Rebbah & Rebbah (1994). For the relationship between the crystal and electronic structures based on the Zintl–Klemn concept for interpreting and predicting the properties of these phases, see: Shevelkov & Shatruk (2001). For isotypic cadmium pnictidohalides, see: Gallay et al. (1975); Kassama et al. (1994) and for isotypic mercury pnictidohalides, see: Labbé et al. (1989); Shevelkov et al. (1996).
Experimental
Crystal data
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Data collection: APEX2 (Bruker, 2006); cell SAINT (Bruker, 2006); data reduction: SAINT; program(s) used to solve structure: SIR97 (Altomare et al., 1999); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: DIAMOND (Brandenburg & Putz, 1999); software used to prepare material for publication: WinGX (Farrugia, 2012) and CRYSCAL (Roisnel, 2013).
Supporting information
CCDC reference: 988028
10.1107/S160053681400395X/vn2080sup1.cif
contains datablock I. DOI:Structure factors: contains datablock I. DOI: 10.1107/S160053681400395X/vn2080Isup2.hkl
Les cristaux de Cd4As2Br3 ont été préparés par transport en phase vapeur à partir d'un mélange stoechiométrique des éléments Cd, As et de CdBr2. Le mélange est broyé puis introduit dans un tube en quartz scellé; des cristaux de couleur rouge foncée sont obtenus après un chauffage à 1073 K durant une semaine.
La structure a été déterminée par isotypie aux halogénopnictures de cadmium et de mercure de formule générale M4A2X3 (M = Cd, Hg; A = P, As, Sb; X = Cl, Br, I). En fin d'affinement, la carte de densité électronique obtenue est: ρmax = 1.932 e Å-3 (localisée à 0.61 Å de C d1) et ρmin = -1.571 e Å-3 (localisée à 1.16 Å de Br1).
Data collection: APEX2 (Bruker, 2006); cell
SAINT (Bruker, 2006); data reduction: SAINT (Bruker, 2006); program(s) used to solve structure: SIR97 (Altomare et al., 1999); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: DIAMOND (Brandenburg & Putz, 1999); software used to prepare material for publication: WinGX (Farrugia, 2012) and CRYSCAL (Roisnel, 2013).Cd4As2Br3 | Dx = 5.54 Mg m−3 |
Mr = 839.17 | Mo Kα radiation, λ = 0.71073 Å |
Cubic, Pa3 | Cell parameters from 1340 reflections |
Hall symbol: -P 2ac 2ab 3 | θ = 2.8–34.9° |
a = 12.625 (4) Å | µ = 26.70 mm−1 |
V = 2012.4 (6) Å3 | T = 150 K |
Z = 8 | Prism, red |
F(000) = 2904 | 0.21 × 0.2 × 0.17 mm |
Bruker APEXII diffractometer | 1238 reflections with I > 2σ(I) |
Graphite monochromator | Rint = 0.088 |
CCD rotation images, thin slices scans | θmax = 34.9°, θmin = 2.8° |
Absorption correction: multi-scan (SADABS; Bruker, 2001) | h = −17→15 |
Tmin = 0.005, Tmax = 0.011 | k = −20→10 |
6624 measured reflections | l = −12→19 |
1485 independent reflections |
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)] = 0.039 | w = 1/[σ2(Fo2) + (0.0052P)2 + 11.0012P] where P = (Fo2 + 2Fc2)/3 |
wR(F2) = 0.092 | (Δ/σ)max = 0.003 |
S = 1.09 | Δρmax = 1.93 e Å−3 |
1485 reflections | Δρmin = −1.57 e Å−3 |
29 parameters | Extinction correction: SHELXL97 (Sheldrick, 2008), Fc*=kFc[1+0.001xFc2λ3/sin(2θ)]-1/4 |
0 restraints | Extinction coefficient: 0.00161 (12) |
Cd4As2Br3 | Z = 8 |
Mr = 839.17 | Mo Kα radiation |
Cubic, Pa3 | µ = 26.70 mm−1 |
a = 12.625 (4) Å | T = 150 K |
V = 2012.4 (6) Å3 | 0.21 × 0.2 × 0.17 mm |
Bruker APEXII diffractometer | 1485 independent reflections |
Absorption correction: multi-scan (SADABS; Bruker, 2001) | 1238 reflections with I > 2σ(I) |
Tmin = 0.005, Tmax = 0.011 | Rint = 0.088 |
6624 measured reflections |
R[F2 > 2σ(F2)] = 0.039 | 0 restraints |
wR(F2) = 0.092 | w = 1/[σ2(Fo2) + (0.0052P)2 + 11.0012P] where P = (Fo2 + 2Fc2)/3 |
S = 1.09 | Δρmax = 1.93 e Å−3 |
1485 reflections | Δρmin = −1.57 e Å−3 |
29 parameters |
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. 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 | ||
Cd1 | 0.02627 (4) | −0.01237 (4) | 0.24906 (3) | 0.00853 (12) | |
Cd2 | 0.21971 (3) | 0.21971 (3) | 0.21971 (3) | 0.00892 (16) | |
As1 | 0.44525 (4) | 0.44525 (4) | 0.44525 (4) | 0.00244 (19) | |
As2 | 0.10239 (5) | 0.10239 (5) | 0.10239 (5) | 0.00298 (19) | |
Br1 | 0.18751 (5) | 0.43173 (4) | 0.26201 (5) | 0.00566 (13) |
U11 | U22 | U33 | U12 | U13 | U23 | |
Cd1 | 0.0091 (2) | 0.0118 (2) | 0.00468 (19) | −0.00282 (14) | 0.00066 (14) | 0.00389 (14) |
Cd2 | 0.00892 (16) | 0.00892 (16) | 0.00892 (16) | −0.00209 (14) | −0.00209 (14) | −0.00209 (14) |
As1 | 0.00244 (19) | 0.00244 (19) | 0.00244 (19) | 0.00002 (17) | 0.00002 (17) | 0.00002 (17) |
As2 | 0.00298 (19) | 0.00298 (19) | 0.00298 (19) | 0.00131 (18) | 0.00131 (18) | 0.00131 (18) |
Br1 | 0.0036 (2) | 0.0050 (2) | 0.0083 (3) | 0.00048 (17) | −0.00135 (18) | −0.00099 (18) |
Cd1—As2 | 2.5400 (5) | As1—As1vi | 2.3945 (19) |
Cd1—As1i | 2.5595 (5) | As1—Cd1vii | 2.5594 (9) |
Cd1—Br1ii | 2.7933 (11) | As1—Cd1viii | 2.5595 (5) |
Cd1—Br1iii | 2.9999 (8) | As1—Cd1ix | 2.5595 (5) |
Cd2—As2 | 2.5655 (13) | As2—Cd1v | 2.5400 (6) |
Cd2—Br1iv | 2.7596 (11) | As2—Cd1iv | 2.5400 (5) |
Cd2—Br1 | 2.7596 (7) | Br1—Cd1x | 2.7932 (11) |
Cd2—Br1v | 2.7596 (7) | Br1—Cd1vii | 2.9999 (8) |
As2—Cd1—As1i | 140.50 (3) | Cd1vii—As1—Cd1viii | 107.99 (2) |
As2—Cd1—Br1ii | 118.24 (3) | As1vi—As1—Cd1ix | 110.91 (2) |
As1i—Cd1—Br1ii | 97.55 (2) | Cd1vii—As1—Cd1ix | 107.99 (2) |
As2—Cd1—Br1iii | 106.62 (2) | Cd1viii—As1—Cd1ix | 107.99 (2) |
As1i—Cd1—Br1iii | 91.57 (2) | Cd1v—As2—Cd1 | 118.414 (12) |
Br1ii—Cd1—Br1iii | 85.291 (15) | Cd1v—As2—Cd1iv | 118.414 (14) |
As2—Cd2—Br1iv | 125.922 (19) | Cd1—As2—Cd1iv | 118.416 (17) |
As2—Cd2—Br1 | 125.923 (19) | Cd1v—As2—Cd2 | 97.29 (3) |
Br1iv—Cd2—Br1 | 89.07 (3) | Cd1—As2—Cd2 | 97.29 (3) |
As2—Cd2—Br1v | 125.922 (17) | Cd1iv—As2—Cd2 | 97.29 (3) |
Br1iv—Cd2—Br1v | 89.07 (3) | Cd2—Br1—Cd1x | 112.19 (2) |
Br1—Cd2—Br1v | 89.07 (2) | Cd2—Br1—Cd1vii | 108.48 (2) |
As1vi—As1—Cd1vii | 110.91 (3) | Cd1x—Br1—Cd1vii | 104.66 (2) |
As1vi—As1—Cd1viii | 110.91 (2) | ||
As1i—Cd1—As2—Cd1v | 90.34 (7) | Br1iv—Cd2—As2—Cd1 | 129.443 (19) |
Br1ii—Cd1—As2—Cd1v | −117.28 (4) | Br1—Cd2—As2—Cd1 | −110.56 (2) |
Br1iii—Cd1—As2—Cd1v | −23.66 (5) | Br1v—Cd2—As2—Cd1 | 9.442 (19) |
As1i—Cd1—As2—Cd1iv | −114.45 (6) | Br1iv—Cd2—As2—Cd1iv | −110.56 (2) |
Br1ii—Cd1—As2—Cd1iv | 37.93 (6) | Br1—Cd2—As2—Cd1iv | 9.443 (19) |
Br1iii—Cd1—As2—Cd1iv | 131.55 (4) | Br1v—Cd2—As2—Cd1iv | 129.44 (2) |
As1i—Cd1—As2—Cd2 | −12.05 (5) | As2—Cd2—Br1—Cd1x | 27.93 (3) |
Br1ii—Cd1—As2—Cd2 | 140.33 (2) | Br1iv—Cd2—Br1—Cd1x | 163.39 (3) |
Br1iii—Cd1—As2—Cd2 | −126.06 (2) | Br1v—Cd2—Br1—Cd1x | −107.53 (3) |
Br1iv—Cd2—As2—Cd1v | 9.443 (19) | As2—Cd2—Br1—Cd1vii | 143.055 (14) |
Br1—Cd2—As2—Cd1v | 129.44 (2) | Br1iv—Cd2—Br1—Cd1vii | −81.486 (14) |
Br1v—Cd2—As2—Cd1v | −110.557 (19) | Br1v—Cd2—Br1—Cd1vii | 7.60 (2) |
Symmetry codes: (i) −x+1/2, y−1/2, z; (ii) −x, y−1/2, −z+1/2; (iii) −y+1/2, z−1/2, x; (iv) y, z, x; (v) z, x, y; (vi) −x+1, −y+1, −z+1; (vii) z, −x+1/2, y+1/2; (viii) y+1/2, z, −x+1/2; (ix) −x+1/2, y+1/2, z; (x) −x, y+1/2, −z+1/2. |
Experimental details
Crystal data | |
Chemical formula | Cd4As2Br3 |
Mr | 839.17 |
Crystal system, space group | Cubic, Pa3 |
Temperature (K) | 150 |
a (Å) | 12.625 (4) |
V (Å3) | 2012.4 (6) |
Z | 8 |
Radiation type | Mo Kα |
µ (mm−1) | 26.70 |
Crystal size (mm) | 0.21 × 0.2 × 0.17 |
Data collection | |
Diffractometer | Bruker APEXII diffractometer |
Absorption correction | Multi-scan (SADABS; Bruker, 2001) |
Tmin, Tmax | 0.005, 0.011 |
No. of measured, independent and observed [I > 2σ(I)] reflections | 6624, 1485, 1238 |
Rint | 0.088 |
(sin θ/λ)max (Å−1) | 0.806 |
Refinement | |
R[F2 > 2σ(F2)], wR(F2), S | 0.039, 0.092, 1.09 |
No. of reflections | 1485 |
No. of parameters | 29 |
w = 1/[σ2(Fo2) + (0.0052P)2 + 11.0012P] where P = (Fo2 + 2Fc2)/3 | |
Δρmax, Δρmin (e Å−3) | 1.93, −1.57 |
Computer programs: APEX2 (Bruker, 2006), SAINT (Bruker, 2006), SIR97 (Altomare et al., 1999), SHELXL97 (Sheldrick, 2008), DIAMOND (Brandenburg & Putz, 1999), WinGX (Farrugia, 2012) and CRYSCAL (Roisnel, 2013).
References
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Le composé Cd4As2Br3 a été étudié au préalable par diffraction des rayons X sur poudre (Suchow & Stemple, 1963; Rebbah & Deschanvres, 1981). Ce composé appartient à la famille des composés semi-conducteurs de formule générale M4A2X3 (M = Cd, Hg; A = P, As, Sb; X = Cl, Br, I), connue sous le nom de halogénopnictures de cadmium et de mercure (Rebbah & Rebbah, 1994; Shevelkov & Shatruk, 2001). La principale caractéristique de ces composés polyanioniques est la présence de liaisons anion-anion (A—A). Dans le composé Cd4As2Br3 il existe deux types d'atomes d'arsenic ayant une coordination tétraédrique légèrement déformée. Les atomes d'arsenic de type As1 sont entourés de trois atomes Cd1 et un atome As1 de même type formant ainsi un doublet As12. Les distances anion-anion As1—As1 [2.3945 (19) Å] et Cd1—As1 [2.5595 (5) Å] sont comparables à celles observées dans d'autres composés polyanioniques de la même famille: Cd4As2I3 [As1—As1 = 2.397 (5) Å et Cd1—As1 = 2.574 (5) Å], Gallay et al. (1975); Hg4As2I3 [As1—As1 = 2.415 (2) Å], Labbé et al. (1989); Hg4As2Br3 [As1—As1 = 2.37 (2) Å], Shevelkov et al. (1996). Les angles Cd1—As1—Cd1 et As1—As1—Cd1 qui valent 107.99 (2)° et 110.91 (2)° respectivement, indiquent un tétraèdre légèrement distordu. Les deux tétraèdres correspondant à une même liaison As1—As1 forment un groupement octaédrique As(1)2Cd6. Les atomes d'arsenic de type As2 ne forment pas de paire anionique et sont entourés de quatre atomes de cadmium: un atome Cd2 à 2.5655 (13) Å et trois atomes Cd1 à 2.5400 (6) Å, ces distances sont très voisines de celles autour de l'atome As1. Le tétraèdre As2Cd4 est aussi légèrement distordu avec des angles Cd1—As2—Cd1 et Cd1—As2—Cd2 de 118.414 (12)° et 97.29 (3)° respectivement. La charpente de cette structure est ainsi form\'ee par des octaèdres As12Cd6 déterminant des files parallèles dans les trois directions. L'interconnexion des ces files est assurées par les tétraèdres As2Cd4, déterminant des cavités occupées par les atomes de brome. Ces atomes de brome assurent la cohésion de la structure par l'intermédiaire de liaisons Cd—Br en reliant d'une part deux groupements octaédriques As12Cd6 et d'autre part un groupement octaédrique As12Cd6 avec un groupement tétraédrique As2Cd4. La plus courte distance 2.7596 (7) Å est proche de celles trouvées dans Cd4P2Br3 [2.733 (2) Å, Kassama et al. 1994] ou dans Cd4PAsBr3 [2.760 (5) Å, Rebbah & Deschanvres, 1981]. Enfin l'équilibre des charges dans ce composé peut s'écrire: Cd4+2As1-2As2-3Br3-.