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The structure of copper(I,II) penta­chromium(III) germanate, Cu(Cu0.44Cr4.56)Ge2O12, contains one Cu position (m2m), one Ge position (m) and three Cr positions (2/m, m and 2). The close-packed structure is described in terms of slabs of edge-sharing Cr3+O6 octa­hedra and isolated CuO4 and GeO4 tetra­hedra. These slabs are aligned parallel to the bc plane and are separated from each other by GeO4 tetra­hedra along a. The tetra­hedral coordination observed for the Cu+/Cu2+ ions represents an unusual feature of the structure. The Cr-O and Cu-O bond lengths are compared with literature data.

Supporting information

cif

Crystallographic Information File (CIF) https://doi.org/10.1107/S0108270107005355/bc3029sup1.cif
Contains datablocks global, I

hkl

Structure factor file (CIF format) https://doi.org/10.1107/S0108270107005355/bc3029Isup2.hkl
Contains datablock I

Computing details top

Data collection: SMART-Plus (Bruker, 2001); cell refinement: SAINT-Plus (Bruker, 2001); data reduction: SAINT-Plus; 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: WinGX (Version 1.70.01; Farrugia, 1999).

Copper(I,II) pentachromium(III) germanate top
Crystal data top
Cu(Cu0.44Cr4.56)Ge2O12Dx = 5.305 Mg m3
Mr = 665.78Mo Kα radiation, λ = 0.71073 Å
Orthorhombic, CmcmCell parameters from 4794 reflections
a = 17.176 (2) Åθ = 2.8–28.8°
b = 8.2272 (10) ŵ = 16.49 mm1
c = 5.8996 (7) ÅT = 295 K
V = 833.68 (17) Å3Needle, black
Z = 40.09 × 0.03 × 0.03 mm
F(000) = 1245
Data collection top
Bruker SMART APEX
diffractometer
481 reflections with I > 2σ(I)
rotation, ω scans at four different φ positionsRint = 0.042
Absorption correction: numerical
via equivalents using X-SHAPE (Stoe & Cie 1996)
θmax = 28.8°, θmin = 2.4°
Tmin = 0.55, Tmax = 0.61h = 2323
4822 measured reflectionsk = 1111
595 independent reflectionsl = 77
Refinement top
Refinement on F262 parameters
Least-squares matrix: full1 restraint
R[F2 > 2σ(F2)] = 0.024 w = 1/[σ2(Fo2) + (0.0261P)2]
where P = (Fo2 + 2Fc2)/3
wR(F2) = 0.053(Δ/σ)max < 0.001
S = 1.04Δρmax = 0.90 e Å3
595 reflectionsΔρmin = 0.71 e Å3
Special details top

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.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top
xyzUiso*/UeqOcc. (<1)
Ge0.33241 (3)0.36288 (6)0.750.00792 (16)
Cu10.50.12451 (12)0.750.0155 (2)
Cr10.50.50.50.0084 (3)0.559 (13)
Cu20.50.50.50.0084 (3)0.441 (13)
Cr20.41363 (4)0.25580 (9)0.250.0053 (2)
Cr30.32827 (4)000.00671 (19)
O10.41206 (19)0.5009 (5)0.750.0122 (8)
O20.33764 (12)0.2404 (3)0.5068 (4)0.0100 (5)
O30.2484 (2)0.4850 (4)0.750.0097 (7)
O40.50.2651 (4)0.4681 (5)0.0109 (7)
O50.40397 (18)0.0209 (4)0.250.0092 (7)
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
Cu10.0141 (5)0.0158 (5)0.0166 (5)000
Ge0.0083 (3)0.0071 (3)0.0084 (3)0.0001 (2)00
Cr10.0088 (5)0.0072 (5)0.0091 (5)000.0022 (4)
Cu20.0088 (5)0.0072 (5)0.0091 (5)000.0022 (4)
Cr20.0064 (4)0.0042 (4)0.0054 (4)0.0001 (3)00
Cr30.0076 (4)0.0062 (4)0.0063 (4)000.0004 (3)
O10.0098 (18)0.0087 (16)0.018 (2)0.0006 (14)00
O20.0118 (12)0.0094 (11)0.0088 (11)0.0006 (10)0.0020 (11)0.0006 (8)
O30.0107 (16)0.0107 (16)0.0077 (14)0.0006 (15)00
O40.0124 (17)0.0122 (16)0.0083 (16)000.0010 (14)
O50.0100 (18)0.0090 (17)0.0086 (18)0.0013 (14)00
Geometric parameters (Å, º) top
Cu1—O4i2.026 (3)Cr3—Cr3viii2.9498 (4)
Cu1—O42.026 (3)Cr1—Cr22.9004 (7)
Cu1—O5ii2.038 (3)Cr2—Cr32.9587 (7)
Cu1—O5iii2.038 (3)Cr2—O51.939 (4)
Ge—O21.755 (2)Cr2—O41.965 (2)
Ge—O2i1.755 (2)Cr2—O4ix1.965 (2)
Ge—O31.757 (3)Cr2—O1v2.002 (4)
Ge—O11.778 (4)Cr2—O2ix2.004 (2)
Cr1—O41.941 (3)Cr2—O22.004 (2)
Cr1—O4iv1.941 (3)Cr3—O51.974 (2)
Cr1—O1v2.111 (2)Cr3—O5x1.974 (2)
Cr1—O1vi2.111 (2)Cr3—O3xi1.982 (2)
Cr1—O12.111 (2)Cr3—O3xii1.982 (2)
Cr1—O1iv2.111 (2)Cr3—O2ix1.985 (2)
Cr1—Cr1vii2.9498 (4)Cr3—O2xiii1.985 (2)
O4i—Cu1—O4110.36 (19)O5—Cr2—O1v174.32 (13)
O4i—Cu1—O5ii109.59 (7)O4—Cr2—O1v88.34 (11)
O4—Cu1—O5ii109.59 (7)O5—Cr2—O2ix83.19 (9)
O4i—Cu1—O5iii109.59 (7)O4—Cr2—O2ix171.58 (9)
O4—Cu1—O5iii109.59 (7)O4ix—Cr2—O2ix89.96 (10)
O5ii—Cu1—O5iii108.1 (2)O1v—Cr2—O2ix93.11 (9)
O2—Ge—O2i109.64 (15)O2ix—Cr2—O298.24 (13)
O2—Ge—O3111.72 (9)Cr1—Cr2—Cr1xiv61.129 (16)
O2i—Ge—O3111.72 (9)Cr1—Cr2—Cr3178.48 (3)
O2—Ge—O1109.10 (10)Cr1xiv—Cr2—Cr3119.516 (9)
O2i—Ge—O1109.10 (10)Cr3—Cr2—Cr3ix59.802 (17)
O3—Ge—O1105.44 (17)O5—Cr3—O5x97.59 (15)
O4—Cr1—O1v85.91 (12)O5—Cr3—O3xi178.52 (14)
O4iv—Cr1—O1v94.09 (12)O5x—Cr3—O3xi82.90 (11)
O1v—Cr1—O188.64 (13)O3xi—Cr3—O3xii96.64 (16)
O1vi—Cr1—O191.36 (13)O5—Cr3—O2ix82.81 (12)
O4—Cr1—O1iv85.91 (12)O5x—Cr3—O2ix91.06 (12)
O4iv—Cr1—O1iv94.09 (12)O3xi—Cr3—O2ix95.79 (11)
Cr2—Cr1—Cr2v118.48 (3)O3xii—Cr3—O2ix90.39 (11)
Cr2iv—Cr1—Cr2v61.53 (3)O2ix—Cr3—O2xiii170.71 (13)
Cr2—Cr1—Cr1vii120.565 (8)Cr3viii—Cr3—Cr3ix180.00 (3)
Cr2iv—Cr1—Cr1vii59.435 (8)Cr3viii—Cr3—Cr2119.901 (9)
O5—Cr2—O495.94 (12)Cr3ix—Cr3—Cr260.099 (9)
O4—Cr2—O4ix81.79 (15)Cr2—Cr3—Cr2x120.59 (4)
Symmetry codes: (i) x, y, z+3/2; (ii) x, y, z+1; (iii) x+1, y, z+1; (iv) x+1, y+1, z+1; (v) x, y+1, z+1; (vi) x+1, y, z; (vii) x+1, y+1, z+1/2; (viii) x, y, z1/2; (ix) x, y, z+1/2; (x) x, y, z; (xi) x+1/2, y1/2, z1; (xii) x+1/2, y+1/2, z+1; (xiii) x, y, z1/2; (xiv) x+1, y+1, z1/2.
Selected structural and polyhedral distortion parameters for (I) top
GeCu1
<T—O> (Å)1.7622.032
<O—O> (Å)2.8763.318
BLDa (%)0.410.30
Vol. (Å3)2.8004.31
TAVb (°)5.3230.55
TQEc1.00131.0001
Sd (v.u.)3.861.28
Cr1Cr2Cr3
<Cr-O> (Å)2.0551.9801.980
<O-O> (Å)2.9062.7802.797
BLDa (%)3.681.180.21
Vol. (Å3)11.4710.2210.20
OAVe (°)12.8429.4734.16
OQEf1.00681.00851.0096
Sd (v.u.)2.523.013.00
(a) Bond-length distortion BLD = (100/n)Σi=1n[{(X-O)i-(<X-O>)}/(<X-O>)], where n = number of bonds, (X-O)i = central cation to oxygen length and <X-O> = average cation–oxygen bond length (Renner & Lehmann, 1986). (b) Tetrahedral angle variance TAV = Σi=1n(Θi - 109.47)2/5 (Robinson et al., 1971). (c) Tetrahedral quadratic elongation TQE = Σi=14(li/lt)2/4, where lt = centre to vertex distance for a regular tetrahedron whose volume is equal to that of the undistorted tetrahedron with bond length li (Robinson et al., 1971). (d) Bond-valence sum S (Brese & O'Keeffe, 1991). (e) Octahedral angle variance OAV = Σi=1n(Θi - 90)2/11 (Robinson et al., 1971). (f) Octahedral quadratic elongation OQE = Σi=16(li/lo)2/6, where lo = centre to vertex distance for a regular octahedron whose volume is equal to that of the undistorted octahedron with bond length li (Robinson et al., 1971).
 

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