Lead germanium oxide

The crystal structure of the title compound, PbGeO₃, shows a three-dimensional framework assembled by Pb₆ and Ge₆ structural building units. The Pb atom is coordinated by five O atoms in square-pyramidal coordination, while the Ge atom is tetra­hedrally coordinated by four O atoms.

Key indicators

• Single-crystal X-ray study
• T = 293 K
• Mean [sigma](e-O) = 0.019 Å
• R factor = 0.050
• wR factor = 0.164
• Data-to-parameter ratio = 13.4

checkCIF/PLATON results

No syntax errors found



Alert level C
PLAT031_ALERT_4_C Refined Extinction Parameter within Range ......       2.75 Sigma
PLAT062_ALERT_4_C Rescale T(min) & T(max) by .....................       0.64
PLAT120_ALERT_1_C Reported SPGR R-3     Inconsistent with Explicit      R-3R
PLAT128_ALERT_4_C Non-standard setting of Space group R-3     ....    R-3r
PLAT144_ALERT_4_C su on alpha    Small or Missing  (x 10000) .....          2 Deg.
PLAT199_ALERT_1_C Check the Reported _cell_measurement_temperature        293 K
PLAT200_ALERT_1_C Check the Reported _diffrn_ambient_temperature .        293 K
PLAT731_ALERT_1_C Bond    Calc  3.6909(17), Rep   3.6910(8) ......       2.12 su-Rat
              PB1  -PB1     1.555   5.665
PLAT731_ALERT_1_C Bond    Calc  3.6909(18), Rep   3.6910(8) ......       2.25 su-Rat
              PB1  -PB1     1.555   6.656

Alert level G
ABSTM02_ALERT_3_G  When printed, the submitted absorption T values will be
            replaced by the scaled T values. Since the ratio of scaled T's
            is identical to the ratio of reported T values, the scaling
            does not imply a change to the absorption corrections used in
            the study.
            Ratio of Tmax expected/reported      0.640
            Tmax scaled      0.176 Tmin scaled      0.132
REFLT03_ALERT_1_G ALERT: Expected hkl max differ from CIF values
           From the CIF: _diffrn_reflns_theta_max           25.50
           From the CIF: _reflns_number_total                628
           From the CIF: _diffrn_reflns_limit_ max hkl   10.    7.   11.
           From the CIF: _diffrn_reflns_limit_ min hkl  -10.   -8.  -11.
           TEST1: Expected hkl limits for theta max
           Calculated maximum hkl   11.   11.   11.
           Calculated minimum hkl  -11.  -11.  -11.

   0 ALERT level A = In general: serious problem
   0 ALERT level B = Potentially serious problem
   9 ALERT level C = Check and explain
   2 ALERT level G = General alerts; check

   6 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
   1 ALERT type 3 Indicator that the structure quality may be low
   4 ALERT type 4 Improvement, methodology, query or suggestion

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Computing details

Data collection: APEX2 (Bruker, 2005); cell refinement: SAINT (Bruker, 2002); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 1997a); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997a); molecular graphics: SHELXTL (Sheldrick, 1997b); software used to prepare material for publication: SHELXTL.

(I)

Crystal data

GeO3Pb	Dx = 6.373 Mg m^−3
Mr = 327.78	Mo Kα radiation, λ = 0.71073 Å
Rhombohedral, R3	Cell parameters from 2654 reflections
Hall symbol: -P 3*	θ = 2.6–25.5°
a = 9.3282 (2) Å	µ = 57.82 mm^−1
α = 113.4560 (2)°	T = 293 K
V = 512.43 (2) Å^3	Block, colourless
Z = 6	0.04 × 0.03 × 0.03 mm
F(000) = 828

Data collection

Bruker Apex2 CCD diffractometer	628 independent reflections
Radiation source: fine-focus sealed tube	553 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.047
ω scans	θmax = 25.5°, θmin = 2.6°
Absorption correction: multi-scan (SADABS; Sheldrick, 2003)	h = −10→10
Tmin = 0.206, Tmax = 0.276	k = −8→7
2654 measured reflections	l = −11→11

Refinement

Refinement on F^2	Primary atom site location: structure-invariant direct methods
Least-squares matrix: full	Secondary atom site location: difference Fourier map
R[F^2 > 2σ(F^2)] = 0.050	w = 1/[σ^2(Fo^2) + (0.1096P)^2] where P = (Fo^2 + 2Fc^2)/3
wR(F^2) = 0.164	(Δ/σ)max = 0.001
S = 1.21	Δρmax = 4.40 e Å^−3
628 reflections	Δρmin = −3.49 e Å^−3
47 parameters	Extinction correction: SHELXL, Fc^*=kFc[1+0.001xFc^2λ^3/sin(2θ)]^-1/4
18 restraints	Extinction coefficient: 0.0022 (8)

Special details

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 (Ų)

	x	y	z	Uiso*/Ueq
Pb1	0.71054 (12)	0.01082 (12)	0.17220 (12)	0.0139 (5)
Ge1	1.2560 (3)	0.5203 (3)	0.6560 (3)	0.0114 (7)
O1	1.033 (2)	0.287 (2)	0.540 (2)	0.018 (3)
O2	1.478 (2)	0.545 (2)	0.777 (2)	0.019 (3)
O3	0.684 (2)	0.265 (2)	0.152 (2)	0.020 (3)

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Pb1	0.0151 (6)	0.0162 (6)	0.0148 (6)	0.0111 (5)	0.0112 (5)	0.0108 (5)
Ge1	0.0109 (12)	0.0089 (11)	0.0113 (12)	0.0056 (10)	0.0067 (10)	0.0065 (10)
O1	0.019 (4)	0.020 (5)	0.015 (4)	0.011 (3)	0.013 (3)	0.012 (3)
O2	0.019 (5)	0.017 (4)	0.021 (5)	0.010 (3)	0.012 (3)	0.015 (4)
O3	0.017 (4)	0.021 (5)	0.021 (5)	0.013 (3)	0.016 (4)	0.011 (3)

Geometric parameters (Å, º)

Pb1—O1^i	2.270 (14)	Ge1—O3^v	1.725 (15)
Pb1—O3^ii	2.416 (15)	Ge1—O2	1.779 (15)
Pb1—O1	2.458 (14)	Ge1—O2^vi	1.781 (15)
Pb1—O3	2.551 (16)	O1—Pb1^vii	2.270 (14)
Pb1—O3^iii	2.590 (15)	O2—Ge1^viii	1.781 (15)
Pb1—Pb1^iv	3.6910 (8)	O3—Ge1^v	1.725 (15)
Pb1—Pb1^ii	3.6910 (8)	O3—Pb1^iv	2.416 (15)
Ge1—O1	1.723 (14)	O3—Pb1^iii	2.590 (15)
O1^i—Pb1—O3^ii	78.6 (6)	O3^iii—Pb1—Pb1^ii	118.2 (3)
O1^i—Pb1—O1	86.5 (5)	Pb1^iv—Pb1—Pb1^ii	118.066 (12)
O3^ii—Pb1—O1	72.9 (5)	O1—Ge1—O3^v	113.3 (7)
O1^i—Pb1—O3	78.1 (5)	O1—Ge1—O2	111.9 (7)
O3^ii—Pb1—O3	153.4 (5)	O3^v—Ge1—O2	106.0 (7)
O1—Pb1—O3	93.1 (5)	O1—Ge1—O2^vi	107.6 (7)
O1^i—Pb1—O3^iii	72.8 (5)	O3^v—Ge1—O2^vi	111.4 (7)
O3^ii—Pb1—O3^iii	101.1 (6)	O2—Ge1—O2^vi	106.6 (9)
O1—Pb1—O3^iii	159.3 (5)	Ge1—O1—Pb1^vii	122.8 (7)
O3—Pb1—O3^iii	84.0 (5)	Ge1—O1—Pb1	128.1 (7)
O1^i—Pb1—Pb1^iv	118.6 (4)	Pb1^vii—O1—Pb1	108.6 (6)
O3^ii—Pb1—Pb1^iv	161.0 (4)	Ge1—O2—Ge1^viii	127.3 (8)
O1—Pb1—Pb1^iv	98.6 (3)	Ge1^v—O3—Pb1^iv	121.8 (7)
O3—Pb1—Pb1^iv	40.6 (3)	Ge1^v—O3—Pb1	126.6 (8)
O3^iii—Pb1—Pb1^iv	92.5 (3)	Pb1^iv—O3—Pb1	96.0 (5)
O1^i—Pb1—Pb1^ii	121.4 (4)	Ge1^v—O3—Pb1^iii	110.9 (7)
O3^ii—Pb1—Pb1^ii	43.4 (4)	Pb1^iv—O3—Pb1^iii	100.2 (5)
O1—Pb1—Pb1^ii	71.5 (4)	Pb1—O3—Pb1^iii	96.0 (5)
O3—Pb1—Pb1^ii	153.0 (3)

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