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Single crystals of dizinc tellurium dibromide trioxide, Zn2(TeO3)Br2, were synthesized via a transport reaction in sealed evacuated silica tubes. The compound has a layered crystal structure in which the building units are [ZnO4Br] distorted square pyramids, [ZnO2Br2] distorted tetra­hedra, and [TeO3E] tetra­hedra (E being the 5s2 lone pair of Te4+) joined through sharing of edges and corners to form layers of no net charge. Bromine atoms and tellurium lone pairs protrude from the surfaces of each layer towards adjacent layers. This new compound Zn2(TeO3)Br2 is isostructural with the synthetic compounds Zn2(TeO3)Cl2, CuZn(TeO3)2, Co2(TeO3)Br2 and the mineral sophiite, Zn2(SeO3)Cl2.

Supporting information

cif

Crystallographic Information File (CIF) https://doi.org/10.1107/S1600536808011252/pk2093sup1.cif
Contains datablocks I, global

hkl

Structure factor file (CIF format) https://doi.org/10.1107/S1600536808011252/pk2093Isup2.hkl
Contains datablock I

Key indicators

  • Single-crystal X-ray study
  • T = 293 K
  • Mean [sigma](Zn-O) = 0.003 Å
  • R factor = 0.022
  • wR factor = 0.055
  • Data-to-parameter ratio = 17.4

checkCIF/PLATON results

No syntax errors found



Alert level A DIFF020_ALERT_1_A _diffrn_standards_interval_count and _diffrn_standards_interval_time are missing. Number of measurements between standards or time (min) between standards. DIFF022_ALERT_1_A _diffrn_standards_decay_% is missing Percentage decrease in standards intensity.
Alert level C PLAT029_ALERT_3_C _diffrn_measured_fraction_theta_full Low ....... 0.96
Alert level G ABSTM02_ALERT_3_G The ratio of expected to reported Tmax/Tmin(RR) is > 2.00 Tmin and Tmax reported: 0.050 0.350 Tmin and Tmax expected: 0.017 0.363 RR = 3.014 Please check that your absorption correction is appropriate. PLAT199_ALERT_1_G Check the Reported _cell_measurement_temperature 293 K PLAT200_ALERT_1_G Check the Reported _diffrn_ambient_temperature . 293 K
2 ALERT level A = In general: serious problem 0 ALERT level B = Potentially serious problem 1 ALERT level C = Check and explain 3 ALERT level G = General alerts; check 4 ALERT type 1 CIF construction/syntax error, inconsistent or missing data 0 ALERT type 2 Indicator that the structure model may be wrong or deficient 2 ALERT type 3 Indicator that the structure quality may be low 0 ALERT type 4 Improvement, methodology, query or suggestion 0 ALERT type 5 Informative message, check

Comment top

The synthesis and crystal structure of the new compound Zn2(TeO3)Br2 is a further result of an ongoing study investigating the rich chemistry of tellurium oxohalides. The tellurium atom has a typical one-sided threefold coordination due to the presence of its lone pair 5 s2 (designated E) and the coordination polyhedron is that of a tetrahedron [TeO3E].

Zn1 is coordinated by two oxygen atoms and two bromine atoms completing a distorted tetrahedron [Zn1O2Br2]. Zn2 is coordinated by four oxygen atoms and one bromine atom to complete a distorted square pyramid [Zn2O4Br]. A distorted octahedron [Zn2O4Br2] is formed if Br1 is also taken into account. However, the distance Zn2–Br1 is long [3.3915 (8) Å] and Zn2 is located on the Br2 side of the oxygen plane. Bond valence sum calculations according to Brown & Altermatt (1985) gives a negligible contribution from Br1 suggesting that it should not be considered bonded to Zn2. The three different building units [Zn1O2Br2], [Zn2O4Br] and [TeO3E] are connected so that infinite layers are formed, see Figure 1.

Each [Zn2O4Br] polyhedron is linked to two other [Zn2O4Br] polyhedra by corner sharing so that infinite chains are formed along [001] throughout the layers. Those chains are separated by [Zn1O2Br2] and [TeO3E] groups. Each [Zn2O4Br] polyhedron further shares three corners with different [Zn1O2Br2] groups. The [Zn2O4Br2] polyhedra also share two corners and one edge with different [TeO3E] groups, see Figure 2. The stereochemically active Te lone-pairs are located in the space in between the layers of the structure, pointing towards the space between the likewise protruding Br atoms of the opposite layer. The shortest cation-anion distances between adjacent layers, Zn1–Br1 3.8914 (8) Å, Zn1–Br2 5.3726 (8) Å, Zn2–Br1 4.6898 (8) Å and Te–Br1 3.3904 (6) Å, are similar to or larger than the cation-cation separation within the layers; Zn1···Zn1 4.2315 (11) Å, Zn1···Zn2 3.3127 (8) Å, Zn2···Zn2 3.8755 (1) Å, Te···Te 4.4788 (6) Å, Te···Zn1 3.4097 (6) Å and Te···Zn2 3.0815 (6) Å. This fact indicates the absence of strong contacts between the charge neutral layers and suggests that they are connected only via van der Waals interactions, see Figure 1. Each layer can thus be considered as an infinite two-dimensional molecule.

Assuming a Te–E radius of 1.25 Å, which is the average found for Te4+–E by Galy et al. (1975), the fractional coordinates for the lone-pair E are; x = -0.0237, y = 0.6565, z = 0.1545. This gives contacts E˙˙˙Br1 and E˙˙˙Br2 of ~2.96 and ~2.81 Å, respectively.

The present compound is isostrucural with Zn2(TeO3)Cl2 (Johnsson & Törnroos. 2003a), CuZn(TeO3)Cl2 (Johnsson & Törnroos, 2003b) and Co2(TeO3)Br2 (Becker et al., 2006). The mineral Sophiite Zn2(SeO3)Cl2 (Semenova et al., 1992) is also to be considered as isostructural with Zn2(TeO3)Br2, although there is a difference in that the coordination around Zn2 in the mineral can be considered to form a distorted octahedron [Zn2O4Cl2] with Zn2 located in the oxygen square plane, rather than a square pyramid [Zn2O4Br] as in Zn2(TeO3)Br2. Related compounds are Co2(TeO3)Cl2 (Becker et al. , 2006) that crystallizes in the monoclinic space group P21/m and Zn2(SeO3)Cl2 (Johnsson & Törnroos, 2007) a synthetic monoclinic (P21/c) polymorph of the mineral sophiite.

Related literature top

For related literature, see: Becker et al. (2006); Johnsson & Törnroos (2003a,b, 2007); Semenova et al. (1992); Brown & Altermatt (1985); Galy et al. (1975).

Experimental top

The synthesis of Zn2(TeO3)Br2 was made by chemical transport reactions in sealed evacuated silica tubes. The compound appeared when searching for new compounds in the system Zn2+—O—Br. The starting materials were ZnO (ABCR, +99%), ZnBr2 (ABCR, +99%), and TeO2 (ABCR, +99%). The preparation of crystals was made from a non stoichiometric mixture of ZnO: ZnBr2: TeO2 = 1:5:4, which after mixing in a mortar was put into a silica tube (length ~6 cm) which was then evacuated. The tube was heated for 120 h at 830 K in a muffle furnace. The product appeared as colourless transparent plate-like single crystals and powder. The crystals were found to be hygroscopic. The synthesis product was characterized in a scanning electron microscope (SEM, Jeol 7000 F) equipped with an energy-dispersive spectrometer on 4 different single crystals giving a composition of 35.7 ± 2.0 at % Zn, 19.4 ± 0.9 at % Te, 44.1 ± 0.8 at % Br. No significant amount of Si originating from the silica tubes was detected; 0.80 ± 0.5 at% Si.

Refinement top

The maximum residual peak (1.08) is located at 0.82 Å from Te and the largest hole (-0.82) at 0.92 Å from Te.

Computing details top

Data collection: CrysAlis CCD (Oxford Diffraction, 2006); cell refinement: CrysAlis RED (Oxford Diffraction, 2006); data reduction: CrysAlis RED (Oxford Diffraction, 2006); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: DIAMOND (Bergerhoff, 1996); software used to prepare material for publication: enCIFer (Allen et al., 2004).

Figures top
[Figure 1] Fig. 1. The layer features in Zn2(TeO3)Br2 along [001].
[Figure 2] Fig. 2. Arrangement of coordination polyhedra around a central [Zn2O4Br] square pyramid. The polyhedra and atom labels are as in Figure 1.
dizinc tellurium dibromide trioxide top
Crystal data top
Zn2(TeO3)Br2F(000) = 1648
Mr = 466.18Dx = 4.725 Mg m3
Orthorhombic, PccnMo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ab 2acCell parameters from 13770 reflections
a = 10.5446 (2) Åθ = 3.7–33.2°
b = 16.0928 (2) ŵ = 23.79 mm1
c = 7.7242 (1) ÅT = 293 K
V = 1310.74 (3) Å3Block, colourless
Z = 80.21 × 0.16 × 0.04 mm
Data collection top
Oxford Diffraction Xcalibur3
diffractometer
1290 independent reflections
Radiation source: fine-focus sealed tube1201 reflections with I > 2σ(I)
Graphite monochromatorRint = 0.026
ϕ and ω scansθmax = 26.3°, θmin = 4.1°
Absorption correction: analytical
(CrysAlis RED; Oxford Diffraction, 2007)
h = 1212
Tmin = 0.05, Tmax = 0.35k = 2020
15561 measured reflectionsl = 99
Refinement top
Refinement on F2Primary atom site location: structure-invariant direct methods
Least-squares matrix: fullSecondary atom site location: difference Fourier map
R[F2 > 2σ(F2)] = 0.022 w = 1/[σ2(Fo2) + (0.0333P)2 + 5.0559P]
where P = (Fo2 + 2Fc2)/3
wR(F2) = 0.055(Δ/σ)max = 0.001
S = 1.09Δρmax = 1.08 e Å3
1290 reflectionsΔρmin = 0.82 e Å3
74 parametersExtinction correction: SHELXL97 (Sheldrick, 2008), Fc*=kFc[1+0.001xFc2λ3/sin(2θ)]-1/4
0 restraintsExtinction coefficient: 0.00342 (15)
Crystal data top
Zn2(TeO3)Br2V = 1310.74 (3) Å3
Mr = 466.18Z = 8
Orthorhombic, PccnMo Kα radiation
a = 10.5446 (2) ŵ = 23.79 mm1
b = 16.0928 (2) ÅT = 293 K
c = 7.7242 (1) Å0.21 × 0.16 × 0.04 mm
Data collection top
Oxford Diffraction Xcalibur3
diffractometer
1290 independent reflections
Absorption correction: analytical
(CrysAlis RED; Oxford Diffraction, 2007)
1201 reflections with I > 2σ(I)
Tmin = 0.05, Tmax = 0.35Rint = 0.026
15561 measured reflections
Refinement top
R[F2 > 2σ(F2)] = 0.02274 parameters
wR(F2) = 0.0550 restraints
S = 1.09Δρmax = 1.08 e Å3
1290 reflectionsΔρmin = 0.82 e Å3
Special details top

Experimental. a multifaceted crystal model based on expressions derived by Clark & Reid (1995)]

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.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top
xyzUiso*/Ueq
Te0.02983 (3)0.592957 (18)0.21187 (3)0.01207 (12)
Zn10.00948 (6)0.39234 (4)0.34333 (7)0.01639 (15)
Zn20.26526 (5)0.52410 (4)0.39968 (7)0.01671 (16)
Br20.20748 (5)0.37261 (3)0.43887 (7)0.02286 (16)
Br10.08838 (7)0.29014 (3)0.15586 (7)0.03163 (18)
O20.1882 (3)0.5524 (2)0.1440 (4)0.0160 (7)
O10.0568 (3)0.4903 (2)0.1969 (4)0.0155 (7)
O30.0906 (3)0.5786 (2)0.4378 (4)0.0158 (7)
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
Te0.0105 (2)0.01301 (18)0.01267 (17)0.00006 (11)0.00162 (10)0.00168 (10)
Zn10.0188 (3)0.0174 (3)0.0130 (3)0.0018 (2)0.0002 (2)0.0011 (2)
Zn20.0110 (3)0.0260 (3)0.0132 (3)0.0033 (2)0.0005 (2)0.0016 (2)
Br20.0163 (3)0.0204 (3)0.0318 (3)0.0013 (2)0.00128 (19)0.00377 (19)
Br10.0530 (4)0.0191 (3)0.0227 (3)0.0070 (3)0.0101 (2)0.0017 (2)
O20.0094 (17)0.0266 (19)0.0120 (14)0.0012 (14)0.0001 (12)0.0007 (13)
O10.0125 (18)0.0165 (16)0.0174 (15)0.0034 (14)0.0037 (13)0.0013 (13)
O30.0138 (18)0.0230 (18)0.0105 (15)0.0024 (15)0.0023 (12)0.0016 (12)
Geometric parameters (Å, º) top
Te—O21.867 (3)Zn1—Br22.4247 (8)
Te—O31.873 (3)Zn2—O2ii2.002 (3)
Te—O11.891 (3)Zn2—O1iii2.033 (3)
Zn1—O3i1.952 (3)Zn2—O32.061 (3)
Zn1—O12.004 (3)Zn2—O22.184 (3)
Zn1—Br12.3438 (8)Zn2—Br22.5310 (8)
O2—Te—O385.00 (14)O2ii—Zn2—O389.30 (13)
O2—Te—O196.31 (15)O1iii—Zn2—O3157.82 (14)
O3—Te—O196.55 (14)O2ii—Zn2—O2153.62 (18)
O3i—Zn1—O1101.01 (14)O1iii—Zn2—O292.03 (12)
O3i—Zn1—Br1123.23 (11)O3—Zn2—O273.00 (12)
O1—Zn1—Br196.62 (10)O2ii—Zn2—Br299.54 (10)
O3i—Zn1—Br2100.43 (10)O1iii—Zn2—Br298.97 (10)
O1—Zn1—Br2120.65 (10)O3—Zn2—Br2100.22 (10)
Br1—Zn1—Br2115.54 (3)O2—Zn2—Br2102.69 (10)
O2ii—Zn2—O1iii98.37 (13)
Symmetry codes: (i) x, y+1, z+1; (ii) x+1/2, y, z+1/2; (iii) x+1/2, y+1, z+1/2.

Experimental details

Crystal data
Chemical formulaZn2(TeO3)Br2
Mr466.18
Crystal system, space groupOrthorhombic, Pccn
Temperature (K)293
a, b, c (Å)10.5446 (2), 16.0928 (2), 7.7242 (1)
V3)1310.74 (3)
Z8
Radiation typeMo Kα
µ (mm1)23.79
Crystal size (mm)0.21 × 0.16 × 0.04
Data collection
DiffractometerOxford Diffraction Xcalibur3
diffractometer
Absorption correctionAnalytical
(CrysAlis RED; Oxford Diffraction, 2007)
Tmin, Tmax0.05, 0.35
No. of measured, independent and
observed [I > 2σ(I)] reflections
15561, 1290, 1201
Rint0.026
(sin θ/λ)max1)0.624
Refinement
R[F2 > 2σ(F2)], wR(F2), S 0.022, 0.055, 1.09
No. of reflections1290
No. of parameters74
Δρmax, Δρmin (e Å3)1.08, 0.82

Computer programs: CrysAlis CCD (Oxford Diffraction, 2006), CrysAlis RED (Oxford Diffraction, 2006), SHELXS97 (Sheldrick, 2008), SHELXL97 (Sheldrick, 2008), DIAMOND (Bergerhoff, 1996), enCIFer (Allen et al., 2004).

 

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