Supporting information
Crystallographic Information File (CIF) https://doi.org/10.1107/S1600536807023264/wm2110sup1.cif | |
Structure factor file (CIF format) https://doi.org/10.1107/S1600536807023264/wm2110Isup2.hkl |
The synthesis of β-K4Ge4Se10 was carried out according to the reported procedure (Wachhold and Kanatzidis, 2000) but with a longer heating time, 48 hrs compared to 32 hrs. Orange needles of K4Ge4Se10 were obtained from a solid-state reaction of K2Se, Ge, and Se by mixing stoichiometric amounts (1:2:4) of 471.46 mg K2Se (prepared following the reported procedure, Wachhold and Kanatzidis, 2000), 435.6 mg Ge (Cerac, 99.999%), and 947.5 mg of Se (Aldrich, 99.5%). The reactants were loaded into a fused-silica tube under N2 atmosphere in a glovebox. The tube was torch-sealed under vacuum and then placed in a furnace. The sample was heated to 1123 K at a rate of 35 K/h, held at 1123 k for 48 h, and then cooled to room temperature at a cooling rate of 35 K/h. The tube was opened under N2, the product was ground and powder X-ray diffraction (PXRD) was carried out. The PXRD did not match with the simulated pattern from the atomic coordinates of known K4Ge4Se10 (P21/m) (Eisenmann and Hansa, 1993). This led us to believe that the current product could be a polymorphic modification and subsequent single-crystal X-ray data revealed different cell parameters and structure solution indicated a new polymorph of K4Ge4Se10 (in P21/c space group, β-phase). The experimental PXRD was in good agreement with the simulated pattern of β-K4Ge4Se10. The finely ground product was air sensitive and decomposed after 20–30 minutes of exposure in air. The single-crystal X-ray data was collected at low temperature (100 K) under a flow of liquid N2 and the crystal did not show any sign of decomposition during the period of data collection. Although β-K4Ge4Se10 was obtained following the reported synthesis procedure (Wachhold and Kanatzidis, 2000; Wachhold et al., 2000), however, they did not report a detailed crystallographic characterization of their K4Ge4Se10 and hence it is unclear whether they also obtained the same polymorph as reported here.
The highest peak and the deepest hole in the final Fourier map are 0.96 Å from Ge4 and 2.16 Å from Se10, respectively.
The structure determination of K4Ge4Se10 was first carried out by Eisenmann and Hansa (1993). The compound was synthesized by stoichiometric combination of elements in an evacuated graphitized silica ampoule at 1073 K. It crystallizes in space group P21/m with cell parameters a = 10.202 (6) Å, b = 11.544 (6) Å, c = 9.806 (6) Å, β = 90.6 (1)°, V = 1154.8 Å3. Wachhold & Kanatzidis (2000) reported the synthesis of K4Ge4Se10 starting with K2Se, Ge and Se, following the same route by which we have synthesized K4Ge4Se10 and determined its crystal structure at 100 K, which reveals that the cell pararmeters are different from those reported by Eisenmann and Hansa (1993). The present β-structure crystallizes in the monoclinic system but with a different space group (P21/c); although there is an obvious metric relationship between the unit cells of the two structures, their symmetries do not allow to transform one structure into another.
Complementary views of the two polymorphs are given in Fig. 1. The structure of β-K4Ge4Se10 contains isolated adamantane-like [Ge4Se10]4- units formed by four corner-shared GeSe4 tetrahedra similar to K4Ge4Se10—P21/m. However, these units are arranged differently in the two polymorphs. In both the structures, anionic adamantane units are stacked one over the other along the c- and b axis for K4Ge4Se10—P21/m and β-K4Ge4Se10, respectively, held together by K+ cations to form a column. Such columns are placed side by side in a layer like arrangement parallel to the ac- and ab-plane, for K4Ge4Se10—P21/m and β-K4Ge4Se10, respectively. In K4Ge4Se10—P21/m the adamantane units are arranged such that [Ge4Se10]4- super tetrahedra are face up in one layer while they are placed face down in the next layer, which means the Se atoms are arranged in opposite directions in alternate layer. However, in the new polymorph, β-K4Ge4Se10, the directions of the super tetrahedra (arrangement of Se atoms) alternate in every two layers (Fig. 1). Thus in β-K4Ge4Se10 the c axis is approximately doubled the length of the b axis in K4Ge4Se10—P21/m. The average Ge—Se distances (d(Ge—Se)endo = 2.378, d(Ge—Se)exo = 2.281 Å; Table 1) and the coordination number of the K+ ions (CN = 5–8) of β-K4Ge4Se10 are comparable to that of K4Ge4Se10—P21/m.
For the first polymorph (P21/m) of this composition, see: Eisenmann & Hansa (1993); for preparation, see: Wachhold & Kanatzidis (2000); Wachhold et al. (2000).
Data collection: SMART (Bruker, 2000); cell refinement: SAINT (Bruker, 2000); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: DIAMOND (Brandenburg, 2005); software used to prepare material for publication: SHELXL97.
Fig. 1. Ball and stick representation of the packing of adamantane units in the two polymorphs: K4Ge4Se10—P21/m (left), β-K4Ge4Se10 (right). |
K4Ge4Se10 | F(000) = 2176 |
Mr = 1236.36 | Dx = 3.669 Mg m−3 |
Monoclinic, P21/c | Mo Kα radiation, λ = 0.71073 Å |
Hall symbol: -P 2ybc | Cell parameters from 5478 reflections |
a = 9.9796 (8) Å | θ = 2.3–28.3° |
b = 9.7047 (8) Å | µ = 22.31 mm−1 |
c = 23.184 (2) Å | T = 100 K |
β = 94.508 (2)° | Irregular, orange |
V = 2238.4 (3) Å3 | 0.26 × 0.12 × 0.06 mm |
Z = 4 |
Bruker SMART CCD area detector diffractometer | 4823 independent reflections |
Radiation source: fine-focus sealed tube | 3896 reflections with I > 2σ(I) |
Graphite monochromator | Rint = 0.069 |
φ and ω scans | θmax = 27.0°, θmin = 1.8° |
Absorption correction: multi-scan (SADABS; Sheldrick, 1996) | h = −12→12 |
Tmin = 0.054, Tmax = 0.262 | k = −12→12 |
19344 measured reflections | l = −29→29 |
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)] = 0.042 | w = 1/[σ2(Fo2) + (0.0511P)2 + 6.4498P] where P = (Fo2 + 2Fc2)/3 |
wR(F2) = 0.103 | (Δ/σ)max < 0.001 |
S = 1.04 | Δρmax = 1.72 e Å−3 |
4823 reflections | Δρmin = −1.47 e Å−3 |
164 parameters | Extinction correction: SHELXL97, Fc*=kFc[1+0.001xFc2λ3/sin(2θ)]-1/4 |
0 restraints | Extinction coefficient: 0.00274 (12) |
K4Ge4Se10 | V = 2238.4 (3) Å3 |
Mr = 1236.36 | Z = 4 |
Monoclinic, P21/c | Mo Kα radiation |
a = 9.9796 (8) Å | µ = 22.31 mm−1 |
b = 9.7047 (8) Å | T = 100 K |
c = 23.184 (2) Å | 0.26 × 0.12 × 0.06 mm |
β = 94.508 (2)° |
Bruker SMART CCD area detector diffractometer | 4823 independent reflections |
Absorption correction: multi-scan (SADABS; Sheldrick, 1996) | 3896 reflections with I > 2σ(I) |
Tmin = 0.054, Tmax = 0.262 | Rint = 0.069 |
19344 measured reflections |
R[F2 > 2σ(F2)] = 0.042 | 164 parameters |
wR(F2) = 0.103 | 0 restraints |
S = 1.04 | Δρmax = 1.72 e Å−3 |
4823 reflections | Δρmin = −1.47 e Å−3 |
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 | ||
Ge1 | 0.05608 (7) | 0.77088 (7) | 0.37483 (3) | 0.01313 (18) | |
Ge2 | 0.84125 (7) | 0.08752 (7) | 0.37930 (3) | 0.01123 (17) | |
Ge3 | 0.72783 (7) | 0.75584 (7) | 0.30709 (3) | 0.01103 (17) | |
Ge4 | 0.73792 (7) | 0.77065 (7) | 0.47074 (3) | 0.01166 (17) | |
Se1 | 0.61852 (7) | 0.67644 (7) | 0.39529 (3) | 0.01264 (16) | |
Se2 | 0.96086 (7) | 0.68890 (7) | 0.46503 (3) | 0.01607 (18) | |
Se3 | 0.27457 (7) | 0.70088 (7) | 0.36540 (3) | 0.01702 (18) | |
Se4 | 0.83817 (7) | 0.32038 (7) | 0.37588 (3) | 0.01580 (18) | |
Se5 | 0.71983 (7) | 0.00069 (7) | 0.30260 (3) | 0.01306 (17) | |
Se6 | 0.72631 (7) | 0.01489 (7) | 0.46832 (3) | 0.01402 (17) | |
Se7 | 0.95299 (7) | 0.67889 (7) | 0.29407 (3) | 0.01363 (17) | |
Se8 | 0.06604 (7) | 0.01348 (7) | 0.37121 (3) | 0.01835 (18) | |
Se9 | 0.61132 (7) | 0.68152 (7) | 0.23270 (3) | 0.01788 (18) | |
Se10 | 0.62389 (7) | 0.69187 (7) | 0.55318 (3) | 0.01533 (17) | |
K1 | 0.84052 (16) | 0.61928 (16) | 0.65528 (7) | 0.0223 (4) | |
K2 | 0.43100 (16) | 0.99728 (15) | 0.39359 (7) | 0.0163 (3) | |
K3 | 0.31801 (17) | 0.62238 (16) | 0.50104 (7) | 0.0221 (4) | |
K4 | 0.67980 (19) | 0.35486 (18) | 0.26208 (8) | 0.0288 (4) |
U11 | U22 | U33 | U12 | U13 | U23 | |
Ge1 | 0.0119 (4) | 0.0106 (3) | 0.0157 (4) | 0.0012 (3) | −0.0064 (3) | −0.0001 (3) |
Ge2 | 0.0138 (4) | 0.0092 (3) | 0.0098 (4) | 0.0003 (3) | −0.0052 (3) | 0.0017 (3) |
Ge3 | 0.0121 (3) | 0.0108 (3) | 0.0090 (4) | 0.0009 (3) | −0.0063 (3) | −0.0009 (3) |
Ge4 | 0.0156 (4) | 0.0089 (3) | 0.0095 (4) | 0.0005 (3) | −0.0049 (3) | 0.0021 (3) |
Se1 | 0.0125 (3) | 0.0121 (3) | 0.0126 (4) | −0.0010 (3) | −0.0044 (3) | 0.0010 (3) |
Se2 | 0.0167 (4) | 0.0141 (3) | 0.0159 (4) | 0.0015 (3) | −0.0083 (3) | 0.0043 (3) |
Se3 | 0.0112 (3) | 0.0153 (3) | 0.0232 (4) | 0.0008 (3) | −0.0072 (3) | −0.0019 (3) |
Se4 | 0.0232 (4) | 0.0098 (3) | 0.0133 (4) | −0.0009 (3) | −0.0058 (3) | 0.0013 (3) |
Se5 | 0.0165 (4) | 0.0111 (3) | 0.0105 (3) | 0.0018 (3) | −0.0065 (3) | 0.0016 (3) |
Se6 | 0.0233 (4) | 0.0092 (3) | 0.0092 (3) | 0.0015 (3) | −0.0013 (3) | 0.0009 (3) |
Se7 | 0.0133 (3) | 0.0132 (3) | 0.0136 (4) | 0.0016 (3) | −0.0038 (3) | −0.0020 (3) |
Se8 | 0.0141 (4) | 0.0122 (3) | 0.0275 (4) | −0.0011 (3) | −0.0063 (3) | 0.0022 (3) |
Se9 | 0.0203 (4) | 0.0177 (4) | 0.0137 (4) | 0.0009 (3) | −0.0113 (3) | −0.0038 (3) |
Se10 | 0.0239 (4) | 0.0116 (3) | 0.0101 (3) | −0.0014 (3) | −0.0017 (3) | 0.0020 (3) |
K1 | 0.0240 (8) | 0.0184 (8) | 0.0233 (9) | −0.0021 (7) | −0.0057 (7) | −0.0017 (7) |
K2 | 0.0188 (8) | 0.0150 (7) | 0.0143 (8) | −0.0010 (6) | −0.0045 (6) | −0.0027 (6) |
K3 | 0.0275 (9) | 0.0182 (8) | 0.0196 (8) | 0.0035 (7) | −0.0052 (7) | −0.0052 (7) |
K4 | 0.0406 (11) | 0.0204 (8) | 0.0220 (9) | −0.0030 (7) | −0.0190 (8) | 0.0049 (7) |
Ge1—Se7i | 2.2492 (10) | Se8—K1v | 3.7468 (18) |
Ge1—Se3 | 2.3105 (10) | Se9—K4 | 3.3027 (19) |
Ge1—Se8ii | 2.3583 (10) | Se9—K4vi | 3.368 (2) |
Ge1—Se2i | 2.4943 (11) | Se9—K2x | 3.4284 (17) |
Ge2—Se5 | 2.2366 (9) | Se9—K1iv | 3.5827 (19) |
Ge2—Se4 | 2.2613 (9) | Se10—K1 | 3.1574 (17) |
Ge2—Se8iii | 2.3769 (10) | Se10—K3 | 3.2640 (18) |
Ge2—Se6 | 2.5384 (10) | Se10—K2xi | 3.3211 (17) |
Ge3—Se9 | 2.1288 (9) | Se10—K3v | 3.3663 (17) |
Ge3—Se5ii | 2.3795 (10) | K1—Se3v | 3.3341 (17) |
Ge3—Se7 | 2.4092 (10) | K1—Se4vii | 3.3929 (19) |
Ge3—Se1 | 2.5131 (10) | K1—Se9xii | 3.5827 (19) |
Ge3—K1iv | 3.9678 (19) | K1—Se7vii | 3.6904 (17) |
Ge4—Se1 | 2.2335 (9) | K1—Se8v | 3.7468 (18) |
Ge4—Se6ii | 2.3735 (9) | K1—Se7xii | 3.8577 (17) |
Ge4—Se2 | 2.3755 (10) | K1—Se5xiii | 3.8882 (19) |
Ge4—Se10 | 2.4238 (10) | K1—Ge3xii | 3.9678 (19) |
Ge4—K3v | 3.9173 (18) | K1—K3v | 4.499 (2) |
Se1—K2 | 3.6314 (16) | K1—K2xi | 4.689 (2) |
Se1—K3v | 3.7879 (18) | K1—K4vii | 5.021 (2) |
Se2—Ge1iii | 2.4943 (11) | K2—Se6ii | 3.3035 (16) |
Se2—K3iii | 3.6537 (18) | K2—Se10xi | 3.3211 (17) |
Se3—K3 | 3.2317 (18) | K2—Se9vi | 3.4284 (17) |
Se3—K2 | 3.3133 (16) | K2—Se8ii | 3.6418 (17) |
Se3—K1v | 3.3341 (17) | K2—Se6v | 3.6768 (18) |
Se3—K4vi | 3.374 (2) | K2—Se5ii | 3.7034 (18) |
Se4—K4 | 2.9859 (17) | K2—K4vi | 3.941 (2) |
Se4—K1vii | 3.3929 (19) | K2—K3 | 4.600 (2) |
Se4—K3v | 3.4028 (19) | K2—K1xi | 4.689 (2) |
Se5—Ge3viii | 2.3795 (10) | K2—K3xi | 4.990 (2) |
Se5—K4 | 3.5773 (18) | K3—Se10v | 3.3663 (17) |
Se5—K2viii | 3.7034 (18) | K3—Se4v | 3.4028 (19) |
Se5—K1ix | 3.8882 (19) | K3—Se6v | 3.6252 (17) |
Se6—Ge4viii | 2.3735 (9) | K3—Se2i | 3.6537 (18) |
Se6—K2viii | 3.3035 (16) | K3—Se1v | 3.7879 (18) |
Se6—K3v | 3.6252 (17) | K3—Ge4v | 3.9173 (18) |
Se6—K2v | 3.6768 (18) | K3—K3v | 4.344 (3) |
Se7—Ge1iii | 2.2492 (10) | K3—K1v | 4.499 (2) |
Se7—K1vii | 3.6904 (17) | K3—K2xi | 4.990 (2) |
Se7—K1iv | 3.8577 (17) | K4—Se9x | 3.368 (2) |
Se8—Ge1viii | 2.3583 (10) | K4—Se3x | 3.374 (2) |
Se8—Ge2i | 2.3769 (10) | K4—K2x | 3.941 (2) |
Se8—K2viii | 3.6418 (17) | K4—K1vii | 5.021 (2) |
Se7i—Ge1—Se3 | 100.24 (4) | Se10—K1—K4vii | 148.33 (6) |
Se7i—Ge1—Se8ii | 112.61 (4) | Se3v—K1—K4vii | 114.13 (4) |
Se3—Ge1—Se8ii | 104.32 (4) | Se4vii—K1—K4vii | 35.31 (3) |
Se7i—Ge1—Se2i | 113.08 (4) | Se9xii—K1—K4vii | 114.14 (4) |
Se3—Ge1—Se2i | 114.21 (4) | Se7vii—K1—K4vii | 54.97 (3) |
Se8ii—Ge1—Se2i | 111.60 (4) | Se8v—K1—K4vii | 76.87 (3) |
Se5—Ge2—Se4 | 110.10 (4) | Se7xii—K1—K4vii | 56.64 (3) |
Se5—Ge2—Se8iii | 106.21 (4) | Se5xiii—K1—K4vii | 91.81 (4) |
Se4—Ge2—Se8iii | 108.04 (4) | Ge3xii—K1—K4vii | 88.53 (4) |
Se5—Ge2—Se6 | 106.89 (4) | K3v—K1—K4vii | 126.72 (5) |
Se4—Ge2—Se6 | 107.47 (4) | K2xi—K1—K4vii | 124.61 (4) |
Se8iii—Ge2—Se6 | 118.02 (4) | Se6ii—K2—Se3 | 122.37 (5) |
Se9—Ge3—Se5ii | 106.77 (4) | Se6ii—K2—Se10xi | 85.67 (4) |
Se9—Ge3—Se7 | 104.41 (4) | Se3—K2—Se10xi | 140.62 (6) |
Se5ii—Ge3—Se7 | 109.42 (4) | Se6ii—K2—Se9vi | 117.77 (5) |
Se9—Ge3—Se1 | 108.11 (4) | Se3—K2—Se9vi | 105.06 (4) |
Se5ii—Ge3—Se1 | 109.06 (4) | Se10xi—K2—Se9vi | 80.26 (4) |
Se7—Ge3—Se1 | 118.41 (3) | Se6ii—K2—Se1 | 66.48 (3) |
Se9—Ge3—K1iv | 63.87 (4) | Se3—K2—Se1 | 59.48 (3) |
Se5ii—Ge3—K1iv | 70.55 (3) | Se10xi—K2—Se1 | 151.02 (5) |
Se7—Ge3—K1iv | 69.59 (3) | Se9vi—K2—Se1 | 119.03 (5) |
Se1—Ge3—K1iv | 170.69 (4) | Se6ii—K2—Se8ii | 155.99 (5) |
Se1—Ge4—Se6ii | 111.61 (4) | Se3—K2—Se8ii | 63.83 (3) |
Se1—Ge4—Se2 | 105.31 (4) | Se10xi—K2—Se8ii | 79.71 (4) |
Se6ii—Ge4—Se2 | 112.11 (4) | Se9vi—K2—Se8ii | 78.53 (3) |
Se1—Ge4—Se10 | 103.52 (4) | Se1—K2—Se8ii | 123.18 (4) |
Se6ii—Ge4—Se10 | 107.97 (4) | Se6ii—K2—Se6v | 88.25 (4) |
Se2—Ge4—Se10 | 116.00 (4) | Se3—K2—Se6v | 85.24 (4) |
Se1—Ge4—K3v | 70.00 (3) | Se10xi—K2—Se6v | 67.14 (3) |
Se6ii—Ge4—K3v | 165.69 (4) | Se9vi—K2—Se6v | 136.72 (5) |
Se2—Ge4—K3v | 80.24 (3) | Se1—K2—Se6v | 102.59 (4) |
Se10—Ge4—K3v | 58.62 (3) | Se8ii—K2—Se6v | 68.58 (3) |
Ge4—Se1—Ge3 | 105.83 (4) | Se6ii—K2—Se5ii | 66.18 (3) |
Ge4—Se1—K2 | 84.27 (3) | Se3—K2—Se5ii | 105.73 (4) |
Ge3—Se1—K2 | 89.12 (3) | Se10xi—K2—Se5ii | 111.23 (4) |
Ge4—Se1—K3v | 76.36 (3) | Se9vi—K2—Se5ii | 63.77 (3) |
Ge3—Se1—K3v | 133.58 (4) | Se1—K2—Se5ii | 65.82 (3) |
K2—Se1—K3v | 136.35 (4) | Se8ii—K2—Se5ii | 137.13 (5) |
Ge4—Se2—Ge1iii | 111.12 (3) | Se6v—K2—Se5ii | 154.29 (5) |
Ge4—Se2—K3iii | 161.33 (4) | Se6ii—K2—K4vi | 132.29 (6) |
Ge1iii—Se2—K3iii | 79.56 (4) | Se3—K2—K4vi | 54.62 (4) |
Ge1—Se3—K3 | 91.87 (4) | Se10xi—K2—K4vi | 128.04 (5) |
Ge1—Se3—K2 | 99.19 (4) | Se9vi—K2—K4vi | 52.69 (4) |
K3—Se3—K2 | 89.29 (4) | Se1—K2—K4vi | 79.42 (4) |
Ge1—Se3—K1v | 88.32 (4) | Se8ii—K2—K4vi | 71.29 (4) |
K3—Se3—K1v | 86.48 (4) | Se6v—K2—K4vi | 132.68 (5) |
K2—Se3—K1v | 171.51 (4) | Se5ii—K2—K4vi | 69.90 (4) |
Ge1—Se3—K4vi | 98.40 (4) | Se6ii—K2—K3 | 90.20 (4) |
K3—Se3—K4vi | 160.00 (5) | Se3—K2—K3 | 44.63 (3) |
K2—Se3—K4vi | 72.21 (4) | Se10xi—K2—K3 | 117.56 (5) |
K1v—Se3—K4vi | 110.82 (5) | Se9vi—K2—K3 | 148.88 (5) |
Ge2—Se4—K4 | 98.50 (4) | Se1—K2—K3 | 57.59 (3) |
Ge2—Se4—K1vii | 99.76 (4) | Se8ii—K2—K3 | 80.00 (4) |
K4—Se4—K1vii | 103.65 (5) | Se6v—K2—K3 | 50.46 (3) |
Ge2—Se4—K3v | 98.03 (4) | Se5ii—K2—K3 | 123.40 (4) |
K4—Se4—K3v | 118.50 (5) | K4vi—K2—K3 | 98.95 (5) |
K1vii—Se4—K3v | 130.79 (4) | Se6ii—K2—K1xi | 124.08 (4) |
Ge2—Se5—Ge3viii | 109.10 (3) | Se3—K2—K1xi | 112.76 (4) |
Ge2—Se5—K4 | 83.63 (4) | Se10xi—K2—K1xi | 42.26 (3) |
Ge3viii—Se5—K4 | 166.82 (4) | Se9vi—K2—K1xi | 49.44 (3) |
Ge2—Se5—K2viii | 87.00 (4) | Se1—K2—K1xi | 166.05 (5) |
Ge3viii—Se5—K2viii | 89.49 (3) | Se8ii—K2—K1xi | 51.60 (3) |
K4—Se5—K2viii | 94.72 (4) | Se6v—K2—K1xi | 87.58 (4) |
Ge2—Se5—K1ix | 128.71 (4) | Se5ii—K2—K1xi | 108.43 (4) |
Ge3viii—Se5—K1ix | 74.21 (3) | K4vi—K2—K1xi | 86.66 (4) |
K4—Se5—K1ix | 95.33 (4) | K3—K2—K1xi | 126.65 (5) |
K2viii—Se5—K1ix | 143.75 (4) | Se6ii—K2—K3xi | 46.55 (3) |
Ge4viii—Se6—Ge2 | 105.79 (3) | Se3—K2—K3xi | 161.67 (5) |
Ge4viii—Se6—K2viii | 90.04 (4) | Se10xi—K2—K3xi | 40.30 (3) |
Ge2—Se6—K2viii | 91.69 (4) | Se9vi—K2—K3xi | 93.19 (4) |
Ge4viii—Se6—K3v | 166.30 (4) | Se1—K2—K3xi | 112.99 (4) |
Ge2—Se6—K3v | 87.68 (4) | Se8ii—K2—K3xi | 119.72 (4) |
K2viii—Se6—K3v | 92.03 (4) | Se6v—K2—K3xi | 80.20 (4) |
Ge4viii—Se6—K2v | 88.32 (3) | Se5ii—K2—K3xi | 83.63 (4) |
Ge2—Se6—K2v | 165.46 (4) | K4vi—K2—K3xi | 143.28 (5) |
K2viii—Se6—K2v | 91.75 (4) | K3—K2—K3xi | 117.06 (4) |
K3v—Se6—K2v | 78.09 (4) | K1xi—K2—K3xi | 77.86 (3) |
Ge1iii—Se7—Ge3 | 98.20 (4) | Se3—K3—Se10 | 111.20 (6) |
Ge1iii—Se7—K1vii | 80.73 (4) | Se3—K3—Se10v | 82.19 (4) |
Ge3—Se7—K1vii | 134.92 (4) | Se10—K3—Se10v | 98.16 (5) |
Ge1iii—Se7—K1iv | 125.24 (4) | Se3—K3—Se4v | 137.92 (6) |
Ge3—Se7—K1iv | 74.58 (3) | Se10—K3—Se4v | 97.61 (4) |
K1vii—Se7—K1iv | 141.46 (3) | Se10v—K3—Se4v | 124.39 (5) |
Ge1viii—Se8—Ge2i | 104.85 (4) | Se3—K3—Se6v | 87.29 (4) |
Ge1viii—Se8—K2viii | 89.79 (3) | Se10—K3—Se6v | 81.47 (4) |
Ge2i—Se8—K2viii | 160.28 (4) | Se10v—K3—Se6v | 168.57 (6) |
Ge1viii—Se8—K1v | 165.28 (5) | Se4v—K3—Se6v | 66.81 (3) |
Ge2i—Se8—K1v | 88.51 (4) | Se3—K3—Se2i | 71.47 (4) |
K2viii—Se8—K1v | 78.78 (4) | Se10—K3—Se2i | 156.24 (5) |
Ge3—Se9—K4 | 93.85 (4) | Se10v—K3—Se2i | 105.56 (4) |
Ge3—Se9—K4vi | 102.68 (4) | Se4v—K3—Se2i | 70.12 (4) |
K4—Se9—K4vi | 129.58 (4) | Se6v—K3—Se2i | 75.01 (3) |
Ge3—Se9—K2x | 153.05 (4) | Se3—K3—Se1v | 143.22 (5) |
K4—Se9—K2x | 71.65 (4) | Se10—K3—Se1v | 79.53 (4) |
K4vi—Se9—K2x | 104.03 (4) | Se10v—K3—Se1v | 61.20 (3) |
Ge3—Se9—K1iv | 83.89 (4) | Se4v—K3—Se1v | 69.98 (4) |
K4—Se9—K1iv | 119.43 (5) | Se6v—K3—Se1v | 129.49 (5) |
K4vi—Se9—K1iv | 109.57 (5) | Se2i—K3—Se1v | 113.06 (5) |
K2x—Se9—K1iv | 83.93 (4) | Se3—K3—Ge4v | 112.46 (5) |
Ge4—Se10—K1 | 108.99 (5) | Se10—K3—Ge4v | 106.30 (4) |
Ge4—Se10—K3 | 104.87 (4) | Se10v—K3—Ge4v | 37.93 (2) |
K1—Se10—K3 | 142.83 (5) | Se4v—K3—Ge4v | 86.46 (4) |
Ge4—Se10—K2xi | 96.19 (4) | Se6v—K3—Ge4v | 153.08 (6) |
K1—Se10—K2xi | 92.71 (4) | Se2i—K3—Ge4v | 93.50 (4) |
K3—Se10—K2xi | 98.54 (4) | Se1v—K3—Ge4v | 33.65 (2) |
Ge4—Se10—K3v | 83.45 (4) | Se3—K3—K3v | 99.58 (6) |
K1—Se10—K3v | 87.13 (4) | Se10—K3—K3v | 50.10 (4) |
K3—Se10—K3v | 81.84 (5) | Se10v—K3—K3v | 48.06 (3) |
K2xi—Se10—K3v | 179.54 (5) | Se4v—K3—K3v | 122.49 (6) |
Se10—K1—Se3v | 83.82 (4) | Se6v—K3—K3v | 130.41 (6) |
Se10—K1—Se4vii | 113.87 (5) | Se2i—K3—K3v | 153.60 (7) |
Se3v—K1—Se4vii | 116.80 (5) | Se1v—K3—K3v | 59.34 (4) |
Se10—K1—Se9xii | 80.14 (4) | Ge4v—K3—K3v | 66.40 (4) |
Se3v—K1—Se9xii | 110.40 (5) | Se3—K3—K1v | 47.71 (3) |
Se4vii—K1—Se9xii | 131.67 (5) | Se10—K3—K1v | 131.72 (5) |
Se10—K1—Se7vii | 138.23 (5) | Se10v—K3—K1v | 44.51 (3) |
Se3v—K1—Se7vii | 59.50 (3) | Se4v—K3—K1v | 127.26 (5) |
Se4vii—K1—Se7vii | 71.92 (4) | Se6v—K3—K1v | 128.57 (5) |
Se9xii—K1—Se7vii | 128.77 (5) | Se2i—K3—K1v | 68.47 (4) |
Se10—K1—Se8v | 80.18 (4) | Se1v—K3—K1v | 98.21 (4) |
Se3v—K1—Se8v | 161.84 (6) | Ge4v—K3—K1v | 65.24 (3) |
Se4vii—K1—Se8v | 63.21 (3) | K3v—K3—K1v | 86.98 (5) |
Se9xii—K1—Se8v | 75.27 (4) | Se3—K3—K2 | 46.08 (3) |
Se7vii—K1—Se8v | 131.15 (5) | Se10—K3—K2 | 77.01 (4) |
Se10—K1—Se7xii | 130.48 (5) | Se10v—K3—K2 | 117.23 (5) |
Se3v—K1—Se7xii | 131.87 (5) | Se4v—K3—K2 | 118.23 (5) |
Se4vii—K1—Se7xii | 82.65 (4) | Se6v—K3—K2 | 51.46 (3) |
Se9xii—K1—Se7xii | 57.56 (3) | Se2i—K3—K2 | 90.73 (4) |
Se7vii—K1—Se7xii | 90.81 (4) | Se1v—K3—K2 | 155.97 (5) |
Se8v—K1—Se7xii | 66.04 (3) | Ge4v—K3—K2 | 154.80 (5) |
Se10—K1—Se5xiii | 118.96 (5) | K3v—K3—K2 | 100.70 (6) |
Se3v—K1—Se5xiii | 73.76 (4) | K1v—K3—K2 | 93.54 (4) |
Se4vii—K1—Se5xiii | 127.01 (5) | Se3—K3—K2xi | 109.01 (5) |
Se9xii—K1—Se5xiii | 57.82 (3) | Se10—K3—K2xi | 41.16 (3) |
Se7vii—K1—Se5xiii | 71.91 (3) | Se10v—K3—K2xi | 139.32 (5) |
Se8v—K1—Se5xiii | 121.81 (5) | Se4v—K3—K2xi | 73.39 (4) |
Se7xii—K1—Se5xiii | 60.61 (3) | Se6v—K3—K2xi | 41.42 (3) |
Se10—K1—Ge3xii | 111.83 (5) | Se2i—K3—K2xi | 115.10 (4) |
Se3v—K1—Ge3xii | 107.08 (5) | Se1v—K3—K2xi | 101.72 (4) |
Se4vii—K1—Ge3xii | 118.34 (4) | Ge4v—K3—K2xi | 135.32 (4) |
Se9xii—K1—Ge3xii | 32.24 (2) | K3v—K3—K2xi | 91.26 (5) |
Se7vii—K1—Ge3xii | 98.47 (4) | K1v—K3—K2xi | 155.67 (5) |
Se8v—K1—Ge3xii | 86.93 (4) | K2—K3—K2xi | 62.94 (4) |
Se7xii—K1—Ge3xii | 35.83 (2) | Se4—K4—Se9 | 112.11 (5) |
Se5xiii—K1—Ge3xii | 35.24 (2) | Se4—K4—Se9x | 108.09 (6) |
Se10—K1—K3v | 48.36 (3) | Se9—K4—Se9x | 108.77 (5) |
Se3v—K1—K3v | 45.81 (3) | Se4—K4—Se3x | 128.74 (6) |
Se4vii—K1—K3v | 101.35 (5) | Se9—K4—Se3x | 106.52 (5) |
Se9xii—K1—K3v | 119.14 (5) | Se9x—K4—Se3x | 89.23 (4) |
Se7vii—K1—K3v | 89.99 (4) | Se4—K4—Se5 | 67.66 (4) |
Se8v—K1—K3v | 116.11 (5) | Se9—K4—Se5 | 173.44 (7) |
Se7xii—K1—K3v | 175.97 (5) | Se9x—K4—Se5 | 65.76 (4) |
Se5xiii—K1—K3v | 115.98 (5) | Se3x—K4—Se5 | 77.56 (4) |
Ge3xii—K1—K3v | 140.14 (5) | Se4—K4—K2x | 159.96 (7) |
Se10—K1—K2xi | 45.02 (3) | Se9—K4—K2x | 55.66 (4) |
Se3v—K1—K2xi | 121.25 (5) | Se9x—K4—K2x | 91.57 (4) |
Se4vii—K1—K2xi | 110.45 (5) | Se3x—K4—K2x | 53.18 (4) |
Se9xii—K1—K2xi | 46.64 (3) | Se5—K4—K2x | 126.51 (5) |
Se7vii—K1—K2xi | 175.36 (5) | Se4—K4—K1vii | 41.05 (3) |
Se8v—K1—K2xi | 49.62 (3) | Se9—K4—K1vii | 101.91 (4) |
Se7xii—K1—K2xi | 85.61 (4) | Se9x—K4—K1vii | 144.16 (5) |
Se5xiii—K1—K2xi | 103.70 (4) | Se3x—K4—K1vii | 99.56 (5) |
Ge3xii—K1—K2xi | 76.90 (4) | Se5—K4—K1vii | 82.21 (4) |
K3v—K1—K2xi | 93.39 (4) | K2x—K4—K1vii | 121.49 (5) |
Symmetry codes: (i) x−1, y, z; (ii) x, y+1, z; (iii) x+1, y, z; (iv) x, −y+3/2, z−1/2; (v) −x+1, −y+1, −z+1; (vi) −x+1, y+1/2, −z+1/2; (vii) −x+2, −y+1, −z+1; (viii) x, y−1, z; (ix) x, −y+1/2, z−1/2; (x) −x+1, y−1/2, −z+1/2; (xi) −x+1, −y+2, −z+1; (xii) x, −y+3/2, z+1/2; (xiii) x, −y+1/2, z+1/2. |
Experimental details
Crystal data | |
Chemical formula | K4Ge4Se10 |
Mr | 1236.36 |
Crystal system, space group | Monoclinic, P21/c |
Temperature (K) | 100 |
a, b, c (Å) | 9.9796 (8), 9.7047 (8), 23.184 (2) |
β (°) | 94.508 (2) |
V (Å3) | 2238.4 (3) |
Z | 4 |
Radiation type | Mo Kα |
µ (mm−1) | 22.31 |
Crystal size (mm) | 0.26 × 0.12 × 0.06 |
Data collection | |
Diffractometer | Bruker SMART CCD area detector |
Absorption correction | Multi-scan (SADABS; Sheldrick, 1996) |
Tmin, Tmax | 0.054, 0.262 |
No. of measured, independent and observed [I > 2σ(I)] reflections | 19344, 4823, 3896 |
Rint | 0.069 |
(sin θ/λ)max (Å−1) | 0.639 |
Refinement | |
R[F2 > 2σ(F2)], wR(F2), S | 0.042, 0.103, 1.04 |
No. of reflections | 4823 |
No. of parameters | 164 |
Δρmax, Δρmin (e Å−3) | 1.72, −1.47 |
Computer programs: SMART (Bruker, 2000), SAINT (Bruker, 2000), SAINT, SHELXS97 (Sheldrick, 1997), SHELXL97 (Sheldrick, 1997), DIAMOND (Brandenburg, 2005), SHELXL97.
Ge1—Se7i | 2.2492 (10) | Ge3—Se9 | 2.1288 (9) |
Ge1—Se3 | 2.3105 (10) | Ge3—Se5ii | 2.3795 (10) |
Ge1—Se8ii | 2.3583 (10) | Ge3—Se7 | 2.4092 (10) |
Ge1—Se2i | 2.4943 (11) | Ge3—Se1 | 2.5131 (10) |
Ge2—Se5 | 2.2366 (9) | Ge4—Se1 | 2.2335 (9) |
Ge2—Se4 | 2.2613 (9) | Ge4—Se6ii | 2.3735 (9) |
Ge2—Se8iii | 2.3769 (10) | Ge4—Se2 | 2.3755 (10) |
Ge2—Se6 | 2.5384 (10) | Ge4—Se10 | 2.4238 (10) |
Symmetry codes: (i) x−1, y, z; (ii) x, y+1, z; (iii) x+1, y, z. |
The structure determination of K4Ge4Se10 was first carried out by Eisenmann and Hansa (1993). The compound was synthesized by stoichiometric combination of elements in an evacuated graphitized silica ampoule at 1073 K. It crystallizes in space group P21/m with cell parameters a = 10.202 (6) Å, b = 11.544 (6) Å, c = 9.806 (6) Å, β = 90.6 (1)°, V = 1154.8 Å3. Wachhold & Kanatzidis (2000) reported the synthesis of K4Ge4Se10 starting with K2Se, Ge and Se, following the same route by which we have synthesized K4Ge4Se10 and determined its crystal structure at 100 K, which reveals that the cell pararmeters are different from those reported by Eisenmann and Hansa (1993). The present β-structure crystallizes in the monoclinic system but with a different space group (P21/c); although there is an obvious metric relationship between the unit cells of the two structures, their symmetries do not allow to transform one structure into another.
Complementary views of the two polymorphs are given in Fig. 1. The structure of β-K4Ge4Se10 contains isolated adamantane-like [Ge4Se10]4- units formed by four corner-shared GeSe4 tetrahedra similar to K4Ge4Se10—P21/m. However, these units are arranged differently in the two polymorphs. In both the structures, anionic adamantane units are stacked one over the other along the c- and b axis for K4Ge4Se10—P21/m and β-K4Ge4Se10, respectively, held together by K+ cations to form a column. Such columns are placed side by side in a layer like arrangement parallel to the ac- and ab-plane, for K4Ge4Se10—P21/m and β-K4Ge4Se10, respectively. In K4Ge4Se10—P21/m the adamantane units are arranged such that [Ge4Se10]4- super tetrahedra are face up in one layer while they are placed face down in the next layer, which means the Se atoms are arranged in opposite directions in alternate layer. However, in the new polymorph, β-K4Ge4Se10, the directions of the super tetrahedra (arrangement of Se atoms) alternate in every two layers (Fig. 1). Thus in β-K4Ge4Se10 the c axis is approximately doubled the length of the b axis in K4Ge4Se10—P21/m. The average Ge—Se distances (d(Ge—Se)endo = 2.378, d(Ge—Se)exo = 2.281 Å; Table 1) and the coordination number of the K+ ions (CN = 5–8) of β-K4Ge4Se10 are comparable to that of K4Ge4Se10—P21/m.