Pb(3)Te(2)O(6)Br(2).

Single crystals of the title compound, trilead(II) bis-[tellurate(IV)] dibromide, have been grown under hydro-thermal conditions. The structure is isotypic with that of the chloride analogue, Pb(3)Te(2)O(6)Cl(2), and consists of three Pb, two Te, two Br and four O atoms in the asymmetric unit. Except for two of the O atoms, all atoms are located on mirror planes. The Pb(3)Te(2)O(6)Br(2) structure can be described as being built up from (∞) (2)[Pb(3)Te(2)O(6)](2+) layers extending parallel to (20) and Br(-) anions between the layers. Cohesion of the structure is accomplished through Pb-Br contacts of two of the three lead atoms, leading to highly asymmetric coordination polyhedra. The lone-pair electrons of both Te(IV) and Pb(II) atoms are stereochemically active and point towards the anionic halide layers.

Related literature

For reports and structures of other compounds in the system PbX 2—PbO—TeO2, where X = Br, Cl, see: Pb3TeO4 X 2 (Charkin et al., 2006 ▶; Porter & Halasyamani, 2003 ▶); Pb3Te2O6 X 2 (Porter & Halasyamani, 2003 ▶). The crystal chemistry of oxotellurate(IV) compounds has been reviewed by Dolgikh (1991 ▶) and Zemann (1971 ▶). For other oxotellurates(IV) prepared under hydro­thermal conditions, see: Weil & Stöger (2007 ▶, 2008 ▶).

Experimental

Crystal data

Pb3Te2O6Br2

M = 1132.59

Monoclinic,

a = 16.9151 (9) Å

b = 5.6813 (3) Å

c = 11.0623 (6) Å

β = 104.046 (1)°

V = 1031.3 (1) Å3

Z = 4

Mo Kα radiation

μ = 62.14 mm−1

T = 296 K

0.18 × 0.10 × 0.04 mm

Data collection

Bruker APEXII CCD diffractometer

Absorption correction: numerical (HABITUS; Herrendorf, 1997 ▶) T min = 0.06, T max = 0.41

3758 measured reflections

1371 independent reflections

1338 reflections with I > 2σ(I)

R int = 0.030

Refinement

R[F 2 > 2σ(F 2)] = 0.048

wR(F 2) = 0.107

S = 1.15

1371 reflections

73 parameters

Δρmax = 7.41 e Å−3

Δρmin = −6.41 e Å−3

Data collection: APEX2 (Bruker, 2008 ▶); cell refinement: SAINT (Bruker, 2008 ▶); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 ▶); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 ▶); molecular graphics: ATOMS (Dowty, 2006 ▶); software used to prepare material for publication: SHELXL97.

Crystal structure: contains datablocks I, global. DOI: 10.1107/S1600536809053604/br2129sup1.cif

Structure factors: contains datablocks I. DOI: 10.1107/S1600536809053604/br2129Isup2.hkl

Additional supplementary materials: crystallographic information; 3D view; checkCIF report

Pb3Te2O6Br2	F(000) = 1872
Mr = 1132.59	Dx = 7.295 Mg m−3
Monoclinic, C2/m	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -C 2y	Cell parameters from 4771 reflections
a = 16.9151 (9) Å	θ = 2.5–32.2°
b = 5.6813 (3) Å	µ = 62.14 mm−1
c = 11.0623 (6) Å	T = 296 K
β = 104.046 (1)°	Rod, colourless
V = 1031.3 (1) Å3	0.18 × 0.10 × 0.04 mm
Z = 4

Bruker APEXII CCD diffractometer	1371 independent reflections
Radiation source: fine-focus sealed tube	1338 reflections with I > 2σ(I)
graphite	Rint = 0.030
ω– and φ–scans	θmax = 27.9°, θmin = 1.9°
Absorption correction: numerical (HABITUS; Herrendorf, 1997)	h = −22→15
Tmin = 0.06, Tmax = 0.41	k = −7→7
3758 measured reflections	l = −13→14

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)] = 0.048	w = 1/[σ2(Fo2) + (0.0166P)2 + 250.8836P] where P = (Fo2 + 2Fc2)/3
wR(F2) = 0.107	(Δ/σ)max < 0.001
S = 1.15	Δρmax = 7.41 e Å−3
1371 reflections	Δρmin = −6.41 e Å−3
73 parameters	Extinction correction: SHELXL97 (Sheldrick, 2008), Fc*=kFc[1+0.001xFc2λ3/sin(2θ)]-1/4
0 restraints	Extinction coefficient: 0.00021 (2)

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
Pb1	0.26158 (6)	0.0000	0.21028 (8)	0.0178 (2)
Pb2	0.02616 (6)	0.0000	0.19788 (9)	0.0250 (3)
Pb3	0.16368 (6)	0.5000	0.39320 (8)	0.0217 (3)
Te1	0.10510 (10)	0.5000	0.04764 (16)	0.0233 (4)
Te2	0.37019 (9)	0.5000	0.41467 (14)	0.0141 (3)
Br1	0.31858 (15)	0.5000	0.0993 (2)	0.0205 (5)
Br2	−0.03969 (16)	0.5000	0.3103 (3)	0.0313 (6)
O1	0.1315 (8)	0.263 (3)	0.1840 (11)	0.028 (3)
O2	0.0000	0.294 (5)	0.0000	0.059 (7)
O3	0.3884 (15)	0.5000	0.5887 (17)	0.040 (5)
O4	0.2909 (7)	0.262 (2)	0.3877 (10)	0.017 (2)

	U11	U22	U33	U12	U13	U23
Pb1	0.0224 (5)	0.0150 (4)	0.0161 (4)	0.000	0.0048 (3)	0.000
Pb2	0.0258 (5)	0.0204 (5)	0.0253 (5)	0.000	−0.0004 (4)	0.000
Pb3	0.0190 (4)	0.0261 (5)	0.0191 (4)	0.000	0.0026 (3)	0.000
Te1	0.0224 (8)	0.0186 (8)	0.0236 (8)	0.000	−0.0046 (6)	0.000
Te2	0.0117 (6)	0.0124 (7)	0.0177 (7)	0.000	0.0025 (5)	0.000
Br1	0.0208 (11)	0.0220 (11)	0.0183 (11)	0.000	0.0039 (9)	0.000
Br2	0.0202 (12)	0.0236 (13)	0.0525 (18)	0.000	0.0131 (12)	0.000
O1	0.032 (7)	0.026 (7)	0.023 (6)	−0.010 (6)	0.005 (5)	0.002 (5)
O2	0.031 (11)	0.062 (18)	0.09 (2)	0.000	0.028 (13)	0.000
O3	0.051 (13)	0.046 (14)	0.011 (8)	0.000	−0.014 (8)	0.000
O4	0.019 (5)	0.016 (6)	0.018 (5)	−0.007 (5)	0.009 (4)	−0.001 (4)

Pb1—O4	2.415 (11)	Pb3—O4viii	2.555 (12)
Pb1—O4i	2.415 (11)	Pb3—O4	2.555 (12)
Pb1—O1i	2.617 (14)	Pb3—O1	2.617 (13)
Pb1—O1	2.617 (14)	Pb3—O1viii	2.617 (13)
Pb1—Br2ii	3.274 (3)	Pb3—O4ix	2.788 (11)
Pb1—Br1iii	3.3287 (13)	Pb3—O4v	2.788 (11)
Pb1—Br1	3.3287 (13)	Pb3—O3v	2.995 (8)
Pb1—Br1iv	3.364 (3)	Pb3—O3x	2.995 (8)
Pb2—O1	2.360 (13)	Pb3—Te2	3.4432 (17)
Pb2—O1i	2.360 (13)	Te1—O1viii	1.989 (13)
Pb2—O3v	2.451 (18)	Te1—O1	1.989 (13)
Pb2—O2vi	2.704 (19)	Te1—O2	2.085 (17)
Pb2—O2	2.704 (19)	Te1—O2xi	2.085 (17)
Pb2—Br2	3.3955 (17)	Te2—O3	1.874 (19)
Pb2—Br2iii	3.3955 (17)	Te2—O4	1.879 (11)
Pb2—Br1vii	3.415 (3)	Te2—O4viii	1.879 (11)
O4—Pb1—O4i	76.0 (5)	O1—Te1—O2	80.4 (6)
O4—Pb1—O1i	116.3 (4)	O1viii—Te1—O2xi	80.4 (6)
O4i—Pb1—O1i	74.9 (4)	O1—Te1—O2xi	126.3 (5)
O4—Pb1—O1	74.9 (4)	O2—Te1—O2xi	68.2 (14)
O4i—Pb1—O1	116.3 (4)	O3—Te2—O4	95.5 (6)
O1i—Pb1—O1	69.7 (6)	O3—Te2—O4viii	95.5 (6)
O1—Pb2—O1i	78.6 (7)	O4—Te2—O4viii	92.3 (7)
O1—Pb2—O3v	77.6 (5)	Te1—O1—Pb2	116.3 (6)
O1i—Pb2—O3v	77.6 (5)	Te1—O1—Pb1	119.9 (6)
O1—Pb2—O2vi	108.5 (4)	Pb2—O1—Pb1	105.0 (5)
O1i—Pb2—O2vi	62.2 (4)	Te1—O1—Pb3	106.4 (6)
O3v—Pb2—O2vi	136.2 (5)	Pb2—O1—Pb3	105.4 (5)
O1—Pb2—O2	62.2 (4)	Pb1—O1—Pb3	101.9 (4)
O1i—Pb2—O2	108.5 (4)	Te1—O2—Te1xi	111.8 (14)
O3v—Pb2—O2	136.2 (5)	Te1—O2—Pb2vi	120.87 (15)
O2vi—Pb2—O2	76.4 (10)	Te1xi—O2—Pb2vi	100.36 (16)
O4viii—Pb3—O4	64.0 (5)	Te1—O2—Pb2	100.36 (16)
O4viii—Pb3—O1	104.3 (4)	Te1xi—O2—Pb2	120.87 (15)
O4—Pb3—O1	72.7 (4)	Pb2vi—O2—Pb2	103.6 (10)
O4viii—Pb3—O1viii	72.7 (4)	Te2—O3—Pb2v	154.3 (13)
O4—Pb3—O1viii	104.3 (4)	Te2—O4—Pb1	124.8 (5)
O1—Pb3—O1viii	61.9 (6)	Te2—O4—Pb3	100.8 (5)
O1viii—Te1—O1	85.1 (8)	Pb1—O4—Pb3	109.7 (4)
O1viii—Te1—O2	126.3 (5)

Distance	X= Br (this work)	X= Cl (Porter & Halasyamani, 2003)
Pb1—O4	2.415 (11)	2.447 (15)
Pb1—O1	2.617 (14)	2.586 (14)
Pb1—X2i	3.274 (3)	3.176 (12)
Pb1—X1	3.3287 (13)	3.237 (12)
Pb1—X1ii	3.364 (3)	3.247 (12)
Pb2—O1	2.360 (13)	2.374 (14)
Pb2—O3iii	2.451 (18)	2.48 (2)
Pb2—O2	2.704 (19)	2.677 (13)
Pb2—X2	3.3955 (17)	3.270 (12)
Pb2—X1iv	3.415 (3)	3.276 (13)
Pb3—O4	2.555 (12)	2.544 (16)
Pb3—O1	2.617 (13)	2.600 (14)
Pb3—O4v	2.788 (11)	2.777 (17)
Pb3—O3iii	2.995 (8)	2.986 (16)
Pb3—X2	3.338 (21)	3.244 (12)
Te1—O1	1.989 (13)	1.938 (13)
Te1—O2	2.085 (17)	2.044 (12)
Te2—O3	1.874 (19)	1.84 (2)
Te2—O4	1.879 (11)	1.861 (16)

Table 1

Comparative geometrical parameters (Å) for selected bond lengths in Pb3Te2O6 X 2 compounds (X = Br, Cl)

Distance	X= Br (this work)	X= Cl (Porter & Halasyamani, 2003 ▶)
Pb1—O4	2.415 (11)	2.447 (15)
Pb1—O1	2.617 (14)	2.586 (14)
Pb1—X2i	3.274 (3)	3.176 (12)
Pb1—X1	3.3287 (13)	3.237 (12)
Pb1—X1ii	3.364 (3)	3.247 (12)
Pb2—O1	2.360 (13)	2.374 (14)
Pb2—O3iii	2.451 (18)	2.48 (2)
Pb2—O2	2.704 (19)	2.677 (13)
Pb2—X2	3.3955 (17)	3.270 (12)
Pb2—X1iv	3.415 (3)	3.276 (13)
Pb3—O4	2.555 (12)	2.544 (16)
Pb3—O1	2.617 (13)	2.600 (14)
Pb3—O4v	2.788 (11)	2.777 (17)
Pb3—O3iii	2.995 (8)	2.986 (16)
Pb3—X2	3.338 (21)	3.244 (12)
Te1—O1	1.989 (13)	1.938 (13)
Te1—O2	2.085 (17)	2.044 (12)
Te2—O3	1.874 (19)	1.84 (2)
Te2—O4	1.879 (11)	1.861 (16)

Symmetry codes: (i) x + , y − , z; (ii) −x + , −y + , −z; (iii) −x + , −y + , −z + 1; (iv) x − , y − , z; (v) −x + , y + , −z + 1.