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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
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)Ge2O12 | Dx = 5.305 Mg m−3 |
Mr = 665.78 | Mo Kα radiation, λ = 0.71073 Å |
Orthorhombic, Cmcm | Cell parameters from 4794 reflections |
a = 17.176 (2) Å | θ = 2.8–28.8° |
b = 8.2272 (10) Å | µ = 16.49 mm−1 |
c = 5.8996 (7) Å | T = 295 K |
V = 833.68 (17) Å3 | Needle, black |
Z = 4 | 0.09 × 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 positions | Rint = 0.042 |
Absorption correction: numerical via equivalents using X-SHAPE (Stoe & Cie 1996) | θmax = 28.8°, θmin = 2.4° |
Tmin = 0.55, Tmax = 0.61 | h = −23→23 |
4822 measured reflections | k = −11→11 |
595 independent reflections | l = −7→7 |
Refinement top
Refinement on F2 | 62 parameters |
Least-squares matrix: full | 1 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 = 1.04 | Δρmax = 0.90 e Å−3 |
595 reflections | Δρmin = −0.71 e Å−3 |
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 | x | y | z | Uiso*/Ueq | Occ. (<1) |
Ge | 0.33241 (3) | 0.36288 (6) | 0.75 | 0.00792 (16) | |
Cu1 | 0.5 | 0.12451 (12) | 0.75 | 0.0155 (2) | |
Cr1 | 0.5 | 0.5 | 0.5 | 0.0084 (3) | 0.559 (13) |
Cu2 | 0.5 | 0.5 | 0.5 | 0.0084 (3) | 0.441 (13) |
Cr2 | 0.41363 (4) | 0.25580 (9) | 0.25 | 0.0053 (2) | |
Cr3 | 0.32827 (4) | 0 | 0 | 0.00671 (19) | |
O1 | 0.41206 (19) | 0.5009 (5) | 0.75 | 0.0122 (8) | |
O2 | 0.33764 (12) | 0.2404 (3) | 0.5068 (4) | 0.0100 (5) | |
O3 | 0.2484 (2) | 0.4850 (4) | 0.75 | 0.0097 (7) | |
O4 | 0.5 | 0.2651 (4) | 0.4681 (5) | 0.0109 (7) | |
O5 | 0.40397 (18) | 0.0209 (4) | 0.25 | 0.0092 (7) | |
Atomic displacement parameters (Å2) top | U11 | U22 | U33 | U12 | U13 | U23 |
Cu1 | 0.0141 (5) | 0.0158 (5) | 0.0166 (5) | 0 | 0 | 0 |
Ge | 0.0083 (3) | 0.0071 (3) | 0.0084 (3) | 0.0001 (2) | 0 | 0 |
Cr1 | 0.0088 (5) | 0.0072 (5) | 0.0091 (5) | 0 | 0 | −0.0022 (4) |
Cu2 | 0.0088 (5) | 0.0072 (5) | 0.0091 (5) | 0 | 0 | −0.0022 (4) |
Cr2 | 0.0064 (4) | 0.0042 (4) | 0.0054 (4) | −0.0001 (3) | 0 | 0 |
Cr3 | 0.0076 (4) | 0.0062 (4) | 0.0063 (4) | 0 | 0 | −0.0004 (3) |
O1 | 0.0098 (18) | 0.0087 (16) | 0.018 (2) | −0.0006 (14) | 0 | 0 |
O2 | 0.0118 (12) | 0.0094 (11) | 0.0088 (11) | −0.0006 (10) | 0.0020 (11) | −0.0006 (8) |
O3 | 0.0107 (16) | 0.0107 (16) | 0.0077 (14) | 0.0006 (15) | 0 | 0 |
O4 | 0.0124 (17) | 0.0122 (16) | 0.0083 (16) | 0 | 0 | −0.0010 (14) |
O5 | 0.0100 (18) | 0.0090 (17) | 0.0086 (18) | 0.0013 (14) | 0 | 0 |
Geometric parameters (Å, º) top
Cu1—O4i | 2.026 (3) | Cr3—Cr3viii | 2.9498 (4) |
Cu1—O4 | 2.026 (3) | Cr1—Cr2 | 2.9004 (7) |
Cu1—O5ii | 2.038 (3) | Cr2—Cr3 | 2.9587 (7) |
Cu1—O5iii | 2.038 (3) | Cr2—O5 | 1.939 (4) |
Ge—O2 | 1.755 (2) | Cr2—O4 | 1.965 (2) |
Ge—O2i | 1.755 (2) | Cr2—O4ix | 1.965 (2) |
Ge—O3 | 1.757 (3) | Cr2—O1v | 2.002 (4) |
Ge—O1 | 1.778 (4) | Cr2—O2ix | 2.004 (2) |
Cr1—O4 | 1.941 (3) | Cr2—O2 | 2.004 (2) |
Cr1—O4iv | 1.941 (3) | Cr3—O5 | 1.974 (2) |
Cr1—O1v | 2.111 (2) | Cr3—O5x | 1.974 (2) |
Cr1—O1vi | 2.111 (2) | Cr3—O3xi | 1.982 (2) |
Cr1—O1 | 2.111 (2) | Cr3—O3xii | 1.982 (2) |
Cr1—O1iv | 2.111 (2) | Cr3—O2ix | 1.985 (2) |
Cr1—Cr1vii | 2.9498 (4) | Cr3—O2xiii | 1.985 (2) |
| | | |
O4i—Cu1—O4 | 110.36 (19) | O5—Cr2—O1v | 174.32 (13) |
O4i—Cu1—O5ii | 109.59 (7) | O4—Cr2—O1v | 88.34 (11) |
O4—Cu1—O5ii | 109.59 (7) | O5—Cr2—O2ix | 83.19 (9) |
O4i—Cu1—O5iii | 109.59 (7) | O4—Cr2—O2ix | 171.58 (9) |
O4—Cu1—O5iii | 109.59 (7) | O4ix—Cr2—O2ix | 89.96 (10) |
O5ii—Cu1—O5iii | 108.1 (2) | O1v—Cr2—O2ix | 93.11 (9) |
O2—Ge—O2i | 109.64 (15) | O2ix—Cr2—O2 | 98.24 (13) |
O2—Ge—O3 | 111.72 (9) | Cr1—Cr2—Cr1xiv | 61.129 (16) |
O2i—Ge—O3 | 111.72 (9) | Cr1—Cr2—Cr3 | 178.48 (3) |
O2—Ge—O1 | 109.10 (10) | Cr1xiv—Cr2—Cr3 | 119.516 (9) |
O2i—Ge—O1 | 109.10 (10) | Cr3—Cr2—Cr3ix | 59.802 (17) |
O3—Ge—O1 | 105.44 (17) | O5—Cr3—O5x | 97.59 (15) |
O4—Cr1—O1v | 85.91 (12) | O5—Cr3—O3xi | 178.52 (14) |
O4iv—Cr1—O1v | 94.09 (12) | O5x—Cr3—O3xi | 82.90 (11) |
O1v—Cr1—O1 | 88.64 (13) | O3xi—Cr3—O3xii | 96.64 (16) |
O1vi—Cr1—O1 | 91.36 (13) | O5—Cr3—O2ix | 82.81 (12) |
O4—Cr1—O1iv | 85.91 (12) | O5x—Cr3—O2ix | 91.06 (12) |
O4iv—Cr1—O1iv | 94.09 (12) | O3xi—Cr3—O2ix | 95.79 (11) |
Cr2—Cr1—Cr2v | 118.48 (3) | O3xii—Cr3—O2ix | 90.39 (11) |
Cr2iv—Cr1—Cr2v | 61.53 (3) | O2ix—Cr3—O2xiii | 170.71 (13) |
Cr2—Cr1—Cr1vii | 120.565 (8) | Cr3viii—Cr3—Cr3ix | 180.00 (3) |
Cr2iv—Cr1—Cr1vii | 59.435 (8) | Cr3viii—Cr3—Cr2 | 119.901 (9) |
O5—Cr2—O4 | 95.94 (12) | Cr3ix—Cr3—Cr2 | 60.099 (9) |
O4—Cr2—O4ix | 81.79 (15) | Cr2—Cr3—Cr2x | 120.59 (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, −z−1/2; (ix) x, y, −z+1/2; (x) x, −y, −z; (xi) −x+1/2, y−1/2, z−1; (xii) −x+1/2, −y+1/2, −z+1; (xiii) x, −y, z−1/2; (xiv) −x+1, −y+1, z−1/2. |
Selected structural and polyhedral distortion parameters for (I) top | Ge | Cu1 | |
<T—O> (Å) | 1.762 | 2.032 | |
<O—O> (Å) | 2.876 | 3.318 | |
BLDa (%) | 0.41 | 0.30 | |
Vol. (Å3) | 2.800 | 4.31 | |
TAVb (°) | 5.323 | 0.55 | |
TQEc | 1.0013 | 1.0001 | |
Sd (v.u.) | 3.86 | 1.28 | |
| | | |
| Cr1 | Cr2 | Cr3 |
<Cr-O> (Å) | 2.055 | 1.980 | 1.980 |
<O-O> (Å) | 2.906 | 2.780 | 2.797 |
BLDa (%) | 3.68 | 1.18 | 0.21 |
Vol. (Å3) | 11.47 | 10.22 | 10.20 |
OAVe (°) | 12.84 | 29.47 | 34.16 |
OQEf | 1.0068 | 1.0085 | 1.0096 |
Sd (v.u.) | 2.52 | 3.01 | 3.00 |
(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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