I8As21Ge25

Ayouz, K.; Kars, M.; Rebbah, A.; Rebbah, H.

doi:10.1107/S1600536809004991

I₈As₂₁Ge₂₅

K. Ayouz, M. Kars, A. Rebbah et H. Rebbah

Single crystals of octaiodine henacosarsenic pentacosagermanium were grown by chemical transport reactions. The structure is isotypic with the analogous clathrates-I. In this structure, the statistically occupied clathrand atoms (As,Ge)₄₆ form bonds in a distorted tetrahedral coordination and their arrangement can define two polyhedra of different sizes; one is an (As,Ge)₂₀ pentagonal dodecahedron, and the other is an (As,Ge)₂₄ tetrakaidecahedron. The guest atom (iodine) resides inside these polyhedra with site symmetry m3 (Wyckoff position 2a) and $\overline{4}$ 2m (Wyckoff position 6d), respectively.

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Supporting information

	Crystallographic Information File (CIF) https://doi.org/10.1107/S1600536809004991/br2095sup1.cif Contains datablocks global, I
	Structure factor file (CIF format) https://doi.org/10.1107/S1600536809004991/br2095Isup2.hkl Contains datablock I

checkCIF report

Key indicators

Single-crystal X-ray study
T = 293 K
Mean () = 0.000 Å
Disorder in main residue
R factor = 0.030
wR factor = 0.037
Data-to-parameter ratio = 40.4

checkCIF/PLATON results

No syntax errors found



Alert level A
PLAT301_ALERT_3_A Main Residue  Disorder .........................      89.00 Perc.

Author Response: Structure refinement shows a statistical occupation of the framework positions 6c, 16i and 24k within the space group Pm3-n. All the Ge/As sites were refined with a total occupancy constrained to unity, see_publ_section_exptl_refinement.


Alert level C
ABSMU01_ALERT_1_C  The ratio of given/expected absorption coefficient lies
               outside the range 0.99 <> 1.01
            Calculated value of mu =    35.205
            Value of mu given      =    34.296
            Value of measurement temperature given =   293.000
            Value of melting point given =     0.000
PLAT041_ALERT_1_C Calc. and Rep. SumFormula Strings    Differ ....          ?
PLAT051_ALERT_1_C Mu(calc) and Mu(CIF) Ratio Differs from 1.0 by .       2.65 Perc.
PLAT068_ALERT_1_C Reported F000 Differs from Calcd (or Missing)...          ?
PLAT951_ALERT_1_C Reported and Calculated Kmax Values Differ by ..          6

Alert level G
ABSTM02_ALERT_3_G  The ratio of expected to reported Tmax/Tmin(RR) is > 1.10
            Tmin and Tmax reported:      0.137     0.330
            Tmin and Tmax expected:      0.091     0.301
            RR =      1.378
            Please check that your absorption correction is appropriate.
REFLT03_ALERT_1_G ALERT: Expected hkl max differ from CIF values
           From the CIF: _diffrn_reflns_theta_max           38.00
           From the CIF: _reflns_number_total                606
           From the CIF: _diffrn_reflns_limit_ max hkl   18.   10.   17.
           From the CIF: _diffrn_reflns_limit_ min hkl  -17.  -12.  -10.
           TEST1: Expected hkl limits for theta max
           Calculated maximum hkl   18.   18.   18.
           Calculated minimum hkl  -18.  -18.  -18.
PLAT860_ALERT_3_G Note: Number of Least-Squares Restraints .......          3
PLAT199_ALERT_1_G Check the Reported _cell_measurement_temperature        293 K
PLAT200_ALERT_1_G Check the Reported _diffrn_ambient_temperature .        293 K

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

   8 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
   3 ALERT type 3 Indicator that the structure quality may be low
   0 ALERT type 4 Improvement, methodology, query or suggestion
   0 ALERT type 5 Informative message, check

Comment top

Les clathrates-I de germanium en particulier ceux encapsulant des halogènes ont connus un regain d'intérêt au cours de ces dernières années, essentiellement en raison de leurs propriétés semiconductrices (Chu et al., 1982) et thermoélectriques très prometteuses (Kishimoto et al., 2006). Les premiers clathrates de ce type synthétisés sont de formulation M₈A₈Ge₃₈ (M: halogènes, A: P, As, Sb) (Menke & von Schnering, 1973) suivi par l'iodide avec I₈Ge_46-_xI_x (x = 8/3) (Nesper et al., 1986). Les structures de ces clathrates ont été déterminées par isotypie aux hydrates de gaz correspondants (Pauling & Marsh, 1952). Dans la structure du composé I₈As₂₁Ge₂₅ tous les atomes clathrands (Ge,As)₄₆ forment des chaînes tétraédriques légèrement distordues, le réseau est alors décrit par la juxtaposition de deux types de polyèdres: les dodécaèdres pentagonaux (Ge,As)₂₀ et les tétrakaīdècaèdres (Ge,As)₂₄. Les sommets de ces polyèdres sont occupés par les atomes de germanium et d'arsenic, alors que les atomes d'iode se logent aux centres des cavités formées par ces deux types de polyèdres. Les distances entre atomes clathrands [2.4456 (6)–2.4925 (9) Å] sont légèrement supérieures à celle observées dans la structure germanium type diamant 2.4498 Å, mais comparables à celles obtenues dans I₈As₈Ge₃₈ [2.4457 (6)–2.4925 (9) Å] (Menke & von Schnering, 1973), ou dans d'autres combinaisons avec le dimère AsGe [2.4457 (6)–2.4925 (9) Å] (Shreeve-Keyer et al., 1997). Les angles de liaisons entre atomes clathrands [104.13 (3)–124.91 (3) °] sont similaires à ceux d'une hybridation sp³ dans la structure germanium type diamant. Enfin, il faut noter que l'agitation thermique (ADP's) autour de l'atome I2 (site 6d) est comparable à celles des autres atomes constituants le clathrate, ce n'est pas le cas de nombreux clathrates au germanium où l'agitation thermique autour de M2 (M: métaux alcalins, Eu) est beaucoup plus large (Nolas et al., 2000).

Related literature top

La synthèse en phase vapeur des premiers clathrates M₈A₈Ge₃₈ (M = halogènes, A = P, As, Sb) est décrite par Menke & von Schnering (1973). Les structures sont isotypes aux hydrates de gaz correspondants (Pauling & Marsh, 1952). Pour les propriétés semiconductrices et thermoélectriques, voir respectivement Chu et al. (1982) et Kishimoto et al. (2006). Pour les propriétés structurales et la conductivité thermique de M₈A₁₆Ge₃₀ (M = Sr, Eu), voir Nolas et al. (2000). Pour autres composées d'intérêt, voir Nespa et al. (1986) et Shreeve-Keyer et al. (1997).

Experimental top

Les monocristaux de I₈As₂₁Ge₂₅ ont été élaborés par transport en phase vapeur à partir d'un mélange stoechiométrique des éléments purs. Le mélange est chauffé dans un tube en quartz scellé pendant 4 jours à 1133 K. Le composé obtenu en fin de réaction est constitué de cristaux stables de forme cubique.

Computing details top

Data collection: KappaCCD Software (Nonius, 1998); cell refinement: KappaCCD Software (Nonius, 1998); data reduction: DENZO and SCALEPACK (Otwinowski & Minor, 1997); program(s) used to solve structure: coordinates taken from analogous clathrates-I (Reference?); program(s) used to refine structure: JANA2000 (Petříček & Dušek, 2000); molecular graphics: GRETEP (Laugier & Bochu, 2002); software used to prepare material for publication: JANA2000 (Petříček & Dušek, 2000).

Figures top

Fig. 1. Projection de la structure de I₈As₂₁Ge₂₅ sur le plan (100) montrant les atomes d'Iode (en rouge); d'Arsenic (en bleu) et de Germanium (en gris), avec un déplacement des ellipsoīdes à 90% de probabilité.

octaiodine henacosarsenic pentacosagermanium top

Crystal data top

I₈As₂₁Ge₂₅	D_x = 6.143 (1) Mg m⁻³
M_r = 4403	Mo Kα radiation, λ = 0.71069 Å
Cubic, Pm3n	Cell parameters from 25 reflections
Hall symbol: -P 4n 2 3	θ = 6.1–38.0°
a = 10.5963 (6) Å	µ = 34.30 mm⁻¹
V = 1189.77 (13) Å³	T = 293 K
Z = 1	Cubic, colourless
F(000) = 1917	0.08 × 0.07 × 0.04 mm

Data collection top

Nonius KappaCCD diffractometer	606 independent reflections
Radiation source: fine-focus sealed tube	454 reflections with I > 3σ(I)
Graphite monochromator	R_int = 0.064
ϕ scans	θ_max = 38.0°, θ_min = 6.1°
Absorption correction: gaussian (JANA2000; Petříček & Dušek, 2000)	h = −17→18
T_min = 0.137, T_max = 0.330	k = −12→10
5499 measured reflections	l = −10→17

Refinement top

Refinement on F	3 restraints
R[F² > 2σ(F²)] = 0.030	Weighting scheme based on measured s.u.'s w = 1/[σ²(F) + 0.0001F²]
wR(F²) = 0.037	(Δ/σ)_max = 0.0001
S = 1.75	Δρ_max = 2.48 e Å⁻³
606 reflections	Δρ_min = −3.60 e Å⁻³
15 parameters

Crystal data top

I₈As₂₁Ge₂₅	Z = 1
M_r = 4403	Mo Kα radiation
Cubic, Pm3n	µ = 34.30 mm⁻¹
a = 10.5963 (6) Å	T = 293 K
V = 1189.77 (13) Å³	0.08 × 0.07 × 0.04 mm

Data collection top

Nonius KappaCCD diffractometer	606 independent reflections
Absorption correction: gaussian (JANA2000; Petříček & Dušek, 2000)	454 reflections with I > 3σ(I)
T_min = 0.137, T_max = 0.330	R_int = 0.064
5499 measured reflections

Refinement top

R[F² > 2σ(F²)] = 0.030	15 parameters
wR(F²) = 0.037	3 restraints
S = 1.75	Δρ_max = 2.48 e Å⁻³
606 reflections	Δρ_min = −3.60 e Å⁻³

Special details top

Refinement. Refinement of F² against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F², conventional R-factors are based on F, with F set to zero for negative F². The threshold expression of F² > n*σ(F²) is used only for calculating R-factors etc. and is not relevant to the choice of reflections for refinement. The program used for refinement, Jana2000, uses the weighting scheme based on the experimental expectations, see _refine_ls_weighting_details, that does not force S to be one. Therefore the values of S are usually larger then the ones from the SHELX program.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å²) top

	x	y	z	U_iso*/U_eq	Occ. (<1)
I1	0	0	0	0.01086 (12)
I2	0.25	0.5	0	0.01537 (14)
Ge3	0	0.31029 (6)	0.11761 (6)	0.01180 (15)	0.971 (4)
As3	0	0.31029 (6)	0.11761 (6)	0.01180 (15)	0.029 (4)
As2	0.18337 (4)	0.18337 (4)	0.18337 (4)	0.01082 (8)	0.900 (4)
Ge2	0.18337 (4)	0.18337 (4)	0.18337 (4)	0.01082 (8)	0.100 (4)
As1	0.25	0	0.5	0.0144 (2)	0.966 (8)
Ge1	0.25	0	0.5	0.0144 (2)	0.034 (8)

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
I1	0.0109 (2)	0.0109 (2)	0.0109 (2)	0	0	0
I2	0.0110 (3)	0.0176 (2)	0.0176 (2)	0	0	0
Ge3	0.0112 (3)	0.0129 (3)	0.0113 (3)	0	0	−0.0009 (2)
As3	0.0112 (3)	0.0129 (3)	0.0113 (3)	0	0	−0.0009 (2)
As2	0.01082 (14)	0.01082 (14)	0.01082 (14)	−0.00079 (13)	−0.00079 (13)	−0.00079 (13)
Ge2	0.01082 (14)	0.01082 (14)	0.01082 (14)	−0.00079 (13)	−0.00079 (13)	−0.00079 (13)
As1	0.0152 (5)	0.0140 (3)	0.0140 (3)	0	0	0
Ge1	0.0152 (5)	0.0140 (3)	0.0140 (3)	0	0	0

Geometric parameters (Å, º) top

I1—Ge3	3.5161 (7)	I2—Ge3	3.5513 (4)
I1—Ge3ⁱ	3.5161 (7)	I2—Ge3^xvi	3.5513 (4)
I1—Ge3ⁱⁱ	3.5161 (7)	I2—Ge3^xvii	3.5513 (4)
I1—Ge3ⁱⁱⁱ	3.5161 (7)	I2—Ge3^v	3.5513 (4)
I1—Ge3^iv	3.5161 (7)	I2—Ge3^xviii	3.5513 (4)
I1—Ge3^v	3.5161 (7)	I2—Ge3^xix	3.5513 (4)
I1—Ge3^vi	3.5161 (7)	I2—Ge3^xx	3.5513 (4)
I1—Ge3^vii	3.5161 (7)	I2—Ge3^xxi	3.5513 (4)
I1—Ge3^viii	3.5161 (7)	I2—As1^xxii	3.7464 (2)
I1—Ge3^ix	3.5161 (7)	I2—As1^xxiii	3.7464 (2)
I1—Ge3^x	3.5161 (7)	I2—As1^xxiv	3.7464 (2)
I1—Ge3^xi	3.5161 (7)	I2—As1^xxv	3.7464 (2)
I1—As2	3.3655 (4)	Ge3—Ge3^v	2.4925 (9)
I1—As2ⁱ	3.3655 (4)	Ge3—As2	2.4636 (6)
I1—As2^xii	3.3655 (4)	Ge3—As2^xiii	2.4636 (6)
I1—As2^xiii	3.3655 (4)	Ge3—As1^xxv	2.4513 (7)
I1—As2^iv	3.3655 (4)	As2—As2^xiii	3.8862 (6)
I1—As2^v	3.3655 (4)	As2—As2^v	3.8862 (6)
I1—As2^xiv	3.3655 (4)	As2—As2^xv	3.8862 (6)
I1—As2^xv	3.3655 (4)	As2—As2^xxvi	2.4457 (6)

Ge3—I1—Ge3ⁱ	180	As2^xiii—I1—As2ⁱ	109.471 (10)
Ge3—I1—Ge3ⁱⁱ	70.644 (10)	As2^xiii—I1—As2^xii	180
Ge3—I1—Ge3ⁱⁱⁱ	109.356 (10)	As2^xiii—I1—As2^iv	70.529 (10)
Ge3—I1—Ge3^iv	138.482 (15)	As2^xiii—I1—As2^v	109.471 (10)
Ge3—I1—Ge3^vi	70.644 (10)	As2^xiii—I1—As2^xiv	70.529 (10)
Ge3—I1—Ge3^vii	109.356 (10)	As2^xiii—I1—As2^xv	109.471 (10)
Ge3—I1—Ge3^viii	70.644 (10)	As2^iv—I1—As2	109.471 (10)
Ge3—I1—Ge3^ix	109.356 (10)	As2^iv—I1—As2ⁱ	70.529 (10)
Ge3—I1—Ge3^x	70.644 (10)	As2^iv—I1—As2^xii	109.471 (10)
Ge3—I1—Ge3^xi	109.356 (10)	As2^iv—I1—As2^xiii	70.529 (10)
Ge3—I1—As2ⁱ	138.117 (9)	As2^iv—I1—As2^v	180
Ge3—I1—As2^xii	138.117 (9)	As2^iv—I1—As2^xiv	109.471 (10)
Ge3—I1—As2^iv	109.587 (11)	As2^iv—I1—As2^xv	70.529 (10)
Ge3—I1—As2^v	70.413 (11)	As2^v—I1—As2	70.529 (10)
Ge3—I1—As2^xiv	70.413 (11)	As2^v—I1—As2ⁱ	109.471 (10)
Ge3—I1—As2^xv	109.587 (11)	As2^v—I1—As2^xii	70.529 (10)
Ge3ⁱ—I1—Ge3	180	As2^v—I1—As2^xiii	109.471 (10)
Ge3ⁱ—I1—Ge3ⁱⁱ	109.356 (10)	As2^v—I1—As2^iv	180
Ge3ⁱ—I1—Ge3ⁱⁱⁱ	70.644 (10)	As2^v—I1—As2^xiv	70.529 (10)
Ge3ⁱ—I1—Ge3^v	138.482 (15)	As2^v—I1—As2^xv	109.471 (10)
Ge3ⁱ—I1—Ge3^vi	109.356 (10)	As2^xiv—I1—As2	109.471 (10)
Ge3ⁱ—I1—Ge3^vii	70.644 (10)	As2^xiv—I1—As2ⁱ	70.529 (10)
Ge3ⁱ—I1—Ge3^viii	109.356 (10)	As2^xiv—I1—As2^xii	109.471 (10)
Ge3ⁱ—I1—Ge3^ix	70.644 (10)	As2^xiv—I1—As2^xiii	70.529 (10)
Ge3ⁱ—I1—Ge3^x	109.356 (10)	As2^xiv—I1—As2^iv	109.471 (10)
Ge3ⁱ—I1—Ge3^xi	70.644 (10)	As2^xiv—I1—As2^v	70.529 (10)
Ge3ⁱ—I1—As2	138.117 (9)	As2^xiv—I1—As2^xv	180
Ge3ⁱ—I1—As2^xiii	138.117 (9)	As2^xv—I1—As2	70.529 (10)
Ge3ⁱ—I1—As2^iv	70.413 (11)	As2^xv—I1—As2ⁱ	109.471 (10)
Ge3ⁱ—I1—As2^v	109.587 (11)	As2^xv—I1—As2^xii	70.529 (10)
Ge3ⁱ—I1—As2^xiv	109.587 (11)	As2^xv—I1—As2^xiii	109.471 (10)
Ge3ⁱ—I1—As2^xv	70.413 (11)	As2^xv—I1—As2^iv	70.529 (10)
Ge3ⁱⁱ—I1—Ge3	70.644 (10)	As2^xv—I1—As2^v	109.471 (10)
Ge3ⁱⁱ—I1—Ge3ⁱ	109.356 (10)	As2^xv—I1—As2^xiv	180
Ge3ⁱⁱ—I1—Ge3ⁱⁱⁱ	180	Ge3—I2—Ge3^xvi	83.521 (11)
Ge3ⁱⁱ—I1—Ge3^iv	70.644 (10)	Ge3—I2—Ge3^xvii	68.952 (13)
Ge3ⁱⁱ—I1—Ge3^v	109.356 (10)	Ge3—I2—Ge3^xviii	162.500 (15)
Ge3ⁱⁱ—I1—Ge3^vii	138.482 (15)	Ge3—I2—Ge3^xix	99.156 (11)
Ge3ⁱⁱ—I1—Ge3^viii	70.644 (10)	Ge3—I2—Ge3^xx	123.809 (13)
Ge3ⁱⁱ—I1—Ge3^ix	109.356 (10)	Ge3—I2—Ge3^xxi	123.809 (13)
Ge3ⁱⁱ—I1—Ge3^x	109.356 (10)	Ge3—I2—As1^xxii	158.083 (10)
Ge3ⁱⁱ—I1—Ge3^xi	70.644 (10)	Ge3—I2—As1^xxiii	97.307 (9)
Ge3ⁱⁱ—I1—As2ⁱ	138.117 (9)	Ge3—I2—As1^xxiv	73.781 (9)
Ge3ⁱⁱ—I1—As2^xii	109.587 (11)	Ge3^xvi—I2—Ge3	83.521 (11)
Ge3ⁱⁱ—I1—As2^xiii	70.413 (11)	Ge3^xvi—I2—Ge3^v	68.952 (13)
Ge3ⁱⁱ—I1—As2^iv	70.413 (11)	Ge3^xvi—I2—Ge3^xviii	99.156 (11)
Ge3ⁱⁱ—I1—As2^v	109.587 (11)	Ge3^xvi—I2—Ge3^xix	162.500 (15)
Ge3ⁱⁱ—I1—As2^xiv	138.117 (9)	Ge3^xvi—I2—Ge3^xx	123.809 (13)
Ge3ⁱⁱⁱ—I1—Ge3	109.356 (10)	Ge3^xvi—I2—Ge3^xxi	123.809 (13)
Ge3ⁱⁱⁱ—I1—Ge3ⁱ	70.644 (10)	Ge3^xvi—I2—As1^xxii	97.307 (9)
Ge3ⁱⁱⁱ—I1—Ge3ⁱⁱ	180	Ge3^xvi—I2—As1^xxiii	158.083 (10)
Ge3ⁱⁱⁱ—I1—Ge3^iv	109.356 (10)	Ge3^xvii—I2—Ge3	68.952 (13)
Ge3ⁱⁱⁱ—I1—Ge3^v	70.644 (10)	Ge3^xvii—I2—Ge3^v	83.521 (11)
Ge3ⁱⁱⁱ—I1—Ge3^vi	138.482 (15)	Ge3^xvii—I2—Ge3^xviii	123.809 (13)
Ge3ⁱⁱⁱ—I1—Ge3^viii	109.356 (10)	Ge3^xvii—I2—Ge3^xix	123.809 (13)
Ge3ⁱⁱⁱ—I1—Ge3^ix	70.644 (10)	Ge3^xvii—I2—Ge3^xx	162.500 (15)
Ge3ⁱⁱⁱ—I1—Ge3^x	70.644 (10)	Ge3^xvii—I2—Ge3^xxi	99.156 (11)
Ge3ⁱⁱⁱ—I1—Ge3^xi	109.356 (10)	Ge3^xvii—I2—As1^xxii	97.307 (9)
Ge3ⁱⁱⁱ—I1—As2	138.117 (9)	Ge3^xvii—I2—As1^xxiii	158.083 (10)
Ge3ⁱⁱⁱ—I1—As2^xii	70.413 (11)	Ge3^xvii—I2—As1^xxiv	73.781 (9)
Ge3ⁱⁱⁱ—I1—As2^xiii	109.587 (11)	Ge3^v—I2—Ge3^xvi	68.952 (13)
Ge3ⁱⁱⁱ—I1—As2^iv	109.587 (11)	Ge3^v—I2—Ge3^xvii	83.521 (11)
Ge3ⁱⁱⁱ—I1—As2^v	70.413 (11)	Ge3^v—I2—Ge3^xviii	123.809 (13)
Ge3ⁱⁱⁱ—I1—As2^xv	138.117 (9)	Ge3^v—I2—Ge3^xix	123.809 (13)
Ge3^iv—I1—Ge3	138.482 (15)	Ge3^v—I2—Ge3^xx	99.156 (11)
Ge3^iv—I1—Ge3ⁱⁱ	70.644 (10)	Ge3^v—I2—Ge3^xxi	162.500 (15)
Ge3^iv—I1—Ge3ⁱⁱⁱ	109.356 (10)	Ge3^v—I2—As1^xxii	158.083 (10)
Ge3^iv—I1—Ge3^v	180	Ge3^v—I2—As1^xxiii	97.307 (9)
Ge3^iv—I1—Ge3^vi	70.644 (10)	Ge3^v—I2—As1^xxv	73.781 (9)
Ge3^iv—I1—Ge3^vii	109.356 (10)	Ge3^xviii—I2—Ge3	162.500 (15)
Ge3^iv—I1—Ge3^viii	109.356 (10)	Ge3^xviii—I2—Ge3^xvi	99.156 (11)
Ge3^iv—I1—Ge3^ix	70.644 (10)	Ge3^xviii—I2—Ge3^xvii	123.809 (13)
Ge3^iv—I1—Ge3^x	109.356 (10)	Ge3^xviii—I2—Ge3^v	123.809 (13)
Ge3^iv—I1—Ge3^xi	70.644 (10)	Ge3^xviii—I2—Ge3^xix	83.521 (11)
Ge3^iv—I1—As2	109.587 (11)	Ge3^xviii—I2—Ge3^xxi	68.952 (13)
Ge3^iv—I1—As2ⁱ	70.413 (11)	Ge3^xviii—I2—As1^xxiii	73.781 (9)
Ge3^iv—I1—As2^xii	70.413 (11)	Ge3^xviii—I2—As1^xxiv	97.307 (9)
Ge3^iv—I1—As2^xiii	109.587 (11)	Ge3^xviii—I2—As1^xxv	158.083 (10)
Ge3^iv—I1—As2^v	138.117 (9)	Ge3^xix—I2—Ge3	99.156 (11)
Ge3^iv—I1—As2^xiv	138.117 (9)	Ge3^xix—I2—Ge3^xvi	162.500 (15)
Ge3^v—I1—Ge3ⁱ	138.482 (15)	Ge3^xix—I2—Ge3^xvii	123.809 (13)
Ge3^v—I1—Ge3ⁱⁱ	109.356 (10)	Ge3^xix—I2—Ge3^v	123.809 (13)
Ge3^v—I1—Ge3ⁱⁱⁱ	70.644 (10)	Ge3^xix—I2—Ge3^xviii	83.521 (11)
Ge3^v—I1—Ge3^iv	180	Ge3^xix—I2—Ge3^xx	68.952 (13)
Ge3^v—I1—Ge3^vi	109.356 (10)	Ge3^xix—I2—As1^xxii	73.781 (9)
Ge3^v—I1—Ge3^vii	70.644 (10)	Ge3^xix—I2—As1^xxiv	158.083 (10)
Ge3^v—I1—Ge3^viii	70.644 (10)	Ge3^xix—I2—As1^xxv	97.307 (9)
Ge3^v—I1—Ge3^ix	109.356 (10)	Ge3^xx—I2—Ge3	123.809 (13)
Ge3^v—I1—Ge3^x	70.644 (10)	Ge3^xx—I2—Ge3^xvi	123.809 (13)
Ge3^v—I1—Ge3^xi	109.356 (10)	Ge3^xx—I2—Ge3^xvii	162.500 (15)
Ge3^v—I1—As2	70.413 (11)	Ge3^xx—I2—Ge3^v	99.156 (11)
Ge3^v—I1—As2ⁱ	109.587 (11)	Ge3^xx—I2—Ge3^xix	68.952 (13)
Ge3^v—I1—As2^xii	109.587 (11)	Ge3^xx—I2—Ge3^xxi	83.521 (11)
Ge3^v—I1—As2^xiii	70.413 (11)	Ge3^xx—I2—As1^xxii	73.781 (9)
Ge3^v—I1—As2^iv	138.117 (9)	Ge3^xx—I2—As1^xxiv	97.307 (9)
Ge3^v—I1—As2^xv	138.117 (9)	Ge3^xx—I2—As1^xxv	158.083 (10)
Ge3^vi—I1—Ge3	70.644 (10)	Ge3^xxi—I2—Ge3	123.809 (13)
Ge3^vi—I1—Ge3ⁱ	109.356 (10)	Ge3^xxi—I2—Ge3^xvi	123.809 (13)
Ge3^vi—I1—Ge3ⁱⁱⁱ	138.482 (15)	Ge3^xxi—I2—Ge3^xvii	99.156 (11)
Ge3^vi—I1—Ge3^iv	70.644 (10)	Ge3^xxi—I2—Ge3^v	162.500 (15)
Ge3^vi—I1—Ge3^v	109.356 (10)	Ge3^xxi—I2—Ge3^xviii	68.952 (13)
Ge3^vi—I1—Ge3^vii	180	Ge3^xxi—I2—Ge3^xx	83.521 (11)
Ge3^vi—I1—Ge3^viii	109.356 (10)	Ge3^xxi—I2—As1^xxiii	73.781 (9)
Ge3^vi—I1—Ge3^ix	70.644 (10)	Ge3^xxi—I2—As1^xxiv	158.083 (10)
Ge3^vi—I1—Ge3^x	70.644 (10)	Ge3^xxi—I2—As1^xxv	97.307 (9)
Ge3^vi—I1—Ge3^xi	109.356 (10)	As1^xxii—I2—As1^xxiii	90
Ge3^vi—I1—As2	70.413 (11)	As1^xxii—I2—As1^xxiv	120
Ge3^vi—I1—As2ⁱ	109.587 (11)	As1^xxii—I2—As1^xxv	120
Ge3^vi—I1—As2^xii	138.117 (9)	As1^xxiii—I2—As1^xxii	90
Ge3^vi—I1—As2^v	138.117 (9)	As1^xxiii—I2—As1^xxiv	120
Ge3^vi—I1—As2^xiv	109.587 (11)	As1^xxiii—I2—As1^xxv	120
Ge3^vi—I1—As2^xv	70.413 (11)	As1^xxiv—I2—As1^xxii	120
Ge3^vii—I1—Ge3	109.356 (10)	As1^xxiv—I2—As1^xxiii	120
Ge3^vii—I1—Ge3ⁱ	70.644 (10)	As1^xxiv—I2—As1^xxv	90
Ge3^vii—I1—Ge3ⁱⁱ	138.482 (15)	As1^xxv—I2—As1^xxii	120
Ge3^vii—I1—Ge3^iv	109.356 (10)	As1^xxv—I2—As1^xxiii	120
Ge3^vii—I1—Ge3^v	70.644 (10)	As1^xxv—I2—As1^xxiv	90
Ge3^vii—I1—Ge3^vi	180	I1—Ge3—I2	113.887 (13)
Ge3^vii—I1—Ge3^viii	70.644 (10)	I1—Ge3—I2^xvi	113.887 (13)
Ge3^vii—I1—Ge3^ix	109.356 (10)	I1—Ge3—Ge3^v	69.24 (2)
Ge3^vii—I1—Ge3^x	109.356 (10)	I1—Ge3—As2	65.785 (17)
Ge3^vii—I1—Ge3^xi	70.644 (10)	I1—Ge3—As2^xiii	65.785 (17)
Ge3^vii—I1—As2	109.587 (11)	I1—Ge3—As1^xxv	165.85 (3)
Ge3^vii—I1—As2ⁱ	70.413 (11)	I2—Ge3—I2^xvi	96.479 (16)
Ge3^vii—I1—As2^xiii	138.117 (9)	I2—Ge3—Ge3^v	69.456 (15)
Ge3^vii—I1—As2^iv	138.117 (9)	I2—Ge3—As2	79.626 (11)
Ge3^vii—I1—As2^xiv	70.413 (11)	I2—Ge3—As2^xiii	175.25 (2)
Ge3^vii—I1—As2^xv	109.587 (11)	I2—Ge3—As1^xxv	74.729 (13)
Ge3^viii—I1—Ge3	70.644 (10)	I2^xvi—Ge3—I2	96.479 (16)
Ge3^viii—I1—Ge3ⁱ	109.356 (10)	I2^xvi—Ge3—Ge3^v	69.456 (15)
Ge3^viii—I1—Ge3ⁱⁱ	70.644 (10)	I2^xvi—Ge3—As2	175.25 (2)
Ge3^viii—I1—Ge3ⁱⁱⁱ	109.356 (10)	I2^xvi—Ge3—As2^xiii	79.626 (11)
Ge3^viii—I1—Ge3^iv	109.356 (10)	I2^xvi—Ge3—As1^xxv	74.729 (13)
Ge3^viii—I1—Ge3^v	70.644 (10)	Ge3^v—Ge3—As2	106.43 (2)
Ge3^viii—I1—Ge3^vi	109.356 (10)	Ge3^v—Ge3—As2^xiii	106.43 (2)
Ge3^viii—I1—Ge3^vii	70.644 (10)	Ge3^v—Ge3—As1^xxv	124.91 (3)
Ge3^viii—I1—Ge3^ix	180	As2—Ge3—As2^xiii	104.13 (3)
Ge3^viii—I1—Ge3^x	138.482 (15)	As2—Ge3—As1^xxv	106.61 (2)
Ge3^viii—I1—As2ⁱ	138.117 (9)	As2^xiii—Ge3—As2	104.13 (3)
Ge3^viii—I1—As2^xii	70.413 (11)	As2^xiii—Ge3—As1^xxv	106.61 (2)
Ge3^viii—I1—As2^xiii	109.587 (11)	I1—As2—Ge3	72.332 (17)
Ge3^viii—I1—As2^iv	138.117 (9)	I1—As2—Ge3ⁱⁱ	72.332 (17)
Ge3^viii—I1—As2^xiv	109.587 (11)	I1—As2—Ge3^viii	72.332 (17)
Ge3^viii—I1—As2^xv	70.413 (11)	I1—As2—As2^xiii	54.736 (9)
Ge3^ix—I1—Ge3	109.356 (10)	I1—As2—As2^v	54.736 (9)
Ge3^ix—I1—Ge3ⁱ	70.644 (10)	I1—As2—As2^xv	54.736 (9)
Ge3^ix—I1—Ge3ⁱⁱ	109.356 (10)	I1—As2—As2^xxvi	180
Ge3^ix—I1—Ge3ⁱⁱⁱ	70.644 (10)	Ge3—As2—Ge3ⁱⁱ	111.21 (2)
Ge3^ix—I1—Ge3^iv	70.644 (10)	Ge3—As2—Ge3^viii	111.21 (2)
Ge3^ix—I1—Ge3^v	109.356 (10)	Ge3—As2—As2^v	73.570 (18)
Ge3^ix—I1—Ge3^vi	70.644 (10)	Ge3—As2—As2^xv	123.08 (2)
Ge3^ix—I1—Ge3^vii	109.356 (10)	Ge3—As2—As2^xxvi	107.67 (2)
Ge3^ix—I1—Ge3^viii	180	Ge3ⁱⁱ—As2—Ge3	111.21 (2)
Ge3^ix—I1—Ge3^xi	138.482 (15)	Ge3ⁱⁱ—As2—Ge3^viii	111.21 (2)
Ge3^ix—I1—As2	138.117 (9)	Ge3ⁱⁱ—As2—As2^xiii	73.570 (18)
Ge3^ix—I1—As2^xii	109.587 (11)	Ge3ⁱⁱ—As2—As2^v	123.08 (2)
Ge3^ix—I1—As2^xiii	70.413 (11)	Ge3ⁱⁱ—As2—As2^xxvi	107.67 (2)
Ge3^ix—I1—As2^v	138.117 (9)	Ge3^viii—As2—Ge3	111.21 (2)
Ge3^ix—I1—As2^xiv	70.413 (11)	Ge3^viii—As2—Ge3ⁱⁱ	111.21 (2)
Ge3^ix—I1—As2^xv	109.587 (11)	Ge3^viii—As2—As2^xiii	123.08 (2)
Ge3^x—I1—Ge3	70.644 (10)	Ge3^viii—As2—As2^xv	73.570 (18)
Ge3^x—I1—Ge3ⁱ	109.356 (10)	Ge3^viii—As2—As2^xxvi	107.67 (2)
Ge3^x—I1—Ge3ⁱⁱ	109.356 (10)	As2^xiii—As2—As2^v	90
Ge3^x—I1—Ge3ⁱⁱⁱ	70.644 (10)	As2^xiii—As2—As2^xv	90
Ge3^x—I1—Ge3^iv	109.356 (10)	As2^xiii—As2—As2^xxvi	125.264 (18)
Ge3^x—I1—Ge3^v	70.644 (10)	As2^v—As2—As2^xiii	90
Ge3^x—I1—Ge3^vi	70.644 (10)	As2^v—As2—As2^xv	90
Ge3^x—I1—Ge3^vii	109.356 (10)	As2^v—As2—As2^xxvi	125.264 (18)
Ge3^x—I1—Ge3^viii	138.482 (15)	As2^xv—As2—As2^xiii	90
Ge3^x—I1—Ge3^xi	180	As2^xv—As2—As2^v	90
Ge3^x—I1—As2	109.587 (11)	As2^xv—As2—As2^xxvi	125.264 (18)
Ge3^x—I1—As2ⁱ	70.413 (11)	As2^xxvi—As2—As2^xiii	125.264 (18)
Ge3^x—I1—As2^xii	138.117 (9)	As2^xxvi—As2—As2^v	125.264 (18)
Ge3^x—I1—As2^iv	70.413 (11)	As2^xxvi—As2—As2^xv	125.264 (18)
Ge3^x—I1—As2^v	109.587 (11)	I2^xxvii—As1—I2^xxviii	90
Ge3^x—I1—As2^xv	138.117 (9)	I2^xxvii—As1—I2^xxix	120
Ge3^xi—I1—Ge3	109.356 (10)	I2^xxvii—As1—I2^xxx	120
Ge3^xi—I1—Ge3ⁱ	70.644 (10)	I2^xxvii—As1—Ge3ⁱⁱ	66.131 (10)
Ge3^xi—I1—Ge3ⁱⁱ	70.644 (10)	I2^xxvii—As1—Ge3^xxxi	66.131 (10)
Ge3^xi—I1—Ge3ⁱⁱⁱ	109.356 (10)	I2^xxvii—As1—Ge3^xxx	79.908 (15)
Ge3^xi—I1—Ge3^iv	70.644 (10)	I2^xxvii—As1—Ge3^xxxii	169.908 (15)
Ge3^xi—I1—Ge3^v	109.356 (10)	I2^xxviii—As1—I2^xxvii	90
Ge3^xi—I1—Ge3^vi	109.356 (10)	I2^xxviii—As1—I2^xxix	120
Ge3^xi—I1—Ge3^vii	70.644 (10)	I2^xxviii—As1—I2^xxx	120
Ge3^xi—I1—Ge3^ix	138.482 (15)	I2^xxviii—As1—Ge3ⁱⁱ	66.131 (10)
Ge3^xi—I1—Ge3^x	180	I2^xxviii—As1—Ge3^xxxi	66.131 (10)
Ge3^xi—I1—As2	70.413 (11)	I2^xxviii—As1—Ge3^xxx	169.908 (15)
Ge3^xi—I1—As2ⁱ	109.587 (11)	I2^xxviii—As1—Ge3^xxxii	79.908 (15)
Ge3^xi—I1—As2^xiii	138.117 (9)	I2^xxix—As1—I2^xxvii	120
Ge3^xi—I1—As2^iv	109.587 (11)	I2^xxix—As1—I2^xxviii	120
Ge3^xi—I1—As2^v	70.413 (11)	I2^xxix—As1—I2^xxx	90
Ge3^xi—I1—As2^xiv	138.117 (9)	I2^xxix—As1—Ge3ⁱⁱ	169.908 (15)
As2—I1—As2ⁱ	180	I2^xxix—As1—Ge3^xxxi	79.908 (15)
As2—I1—As2^xii	109.471 (10)	I2^xxix—As1—Ge3^xxx	66.131 (10)
As2—I1—As2^xiii	70.529 (10)	I2^xxix—As1—Ge3^xxxii	66.131 (10)
As2—I1—As2^iv	109.471 (10)	I2^xxx—As1—I2^xxvii	120
As2—I1—As2^v	70.529 (10)	I2^xxx—As1—I2^xxviii	120
As2—I1—As2^xiv	109.471 (10)	I2^xxx—As1—I2^xxix	90
As2—I1—As2^xv	70.529 (10)	I2^xxx—As1—Ge3ⁱⁱ	79.908 (15)
As2ⁱ—I1—As2	180	I2^xxx—As1—Ge3^xxxi	169.908 (15)
As2ⁱ—I1—As2^xii	70.529 (10)	I2^xxx—As1—Ge3^xxx	66.131 (10)
As2ⁱ—I1—As2^xiii	109.471 (10)	I2^xxx—As1—Ge3^xxxii	66.131 (10)
As2ⁱ—I1—As2^iv	70.529 (10)	Ge3ⁱⁱ—As1—Ge3^xxxi	110.18 (2)
As2ⁱ—I1—As2^v	109.471 (10)	Ge3ⁱⁱ—As1—Ge3^xxx	109.116 (11)
As2ⁱ—I1—As2^xiv	70.529 (10)	Ge3ⁱⁱ—As1—Ge3^xxxii	109.116 (11)
As2ⁱ—I1—As2^xv	109.471 (10)	Ge3^xxxi—As1—Ge3ⁱⁱ	110.18 (2)
As2^xii—I1—As2	109.471 (10)	Ge3^xxxi—As1—Ge3^xxx	109.116 (11)
As2^xii—I1—As2ⁱ	70.529 (10)	Ge3^xxxi—As1—Ge3^xxxii	109.116 (11)
As2^xii—I1—As2^xiii	180	Ge3^xxx—As1—Ge3ⁱⁱ	109.116 (11)
As2^xii—I1—As2^iv	109.471 (10)	Ge3^xxx—As1—Ge3^xxxi	109.116 (11)
As2^xii—I1—As2^v	70.529 (10)	Ge3^xxx—As1—Ge3^xxxii	110.18 (2)
As2^xii—I1—As2^xiv	109.471 (10)	Ge3^xxxii—As1—Ge3ⁱⁱ	109.116 (11)
As2^xii—I1—As2^xv	70.529 (10)	Ge3^xxxii—As1—Ge3^xxxi	109.116 (11)
As2^xiii—I1—As2	70.529 (10)	Ge3^xxxii—As1—Ge3^xxx	110.18 (2)

Symmetry codes: (i) −x, −y, −z; (ii) z, x, y; (iii) −z, −x, −y; (iv) −x, −y, z; (v) x, y, −z; (vi) −z, −x, y; (vii) z, x, −y; (viii) y, z, x; (ix) −y, −z, −x; (x) −y, z, −x; (xi) y, −z, x; (xii) x, −y, −z; (xiii) −x, y, z; (xiv) −x, y, −z; (xv) x, −y, z; (xvi) −x, −y+1, −z; (xvii) −x, −y+1, z; (xviii) −x+1/2, z+1/2, y−1/2; (xix) x+1/2, −z+1/2, −y+1/2; (xx) x+1/2, −z+1/2, y−1/2; (xxi) −x+1/2, z+1/2, −y+1/2; (xxii) −y+1/2, x+1/2, z−1/2; (xxiii) y+1/2, −x+1/2, −z+1/2; (xxiv) z−1/2, −y+1/2, x−1/2; (xxv) −z+1/2, y+1/2, −x+1/2; (xxvi) −y+1/2, −x+1/2, −z+1/2; (xxvii) −y+1/2, x−1/2, z+1/2; (xxviii) y−1/2, −x+1/2, −z+1/2; (xxix) z+1/2, −y+1/2, x+1/2; (xxx) −z+1/2, y−1/2, −x+1/2; (xxxi) z, x, −y+1; (xxxii) −z+1/2, −y+1/2, x+1/2.

Experimental details

Crystal data
Chemical formula	I₈As₂₁Ge₂₅
M_r	4403
Crystal system, space group	Cubic, Pm3n
Temperature (K)	293
a (Å)	10.5963 (6)
V (Å³)	1189.77 (13)
Z	1
Radiation type	Mo Kα
µ (mm⁻¹)	34.30
Crystal size (mm)	0.08 × 0.07 × 0.04

Data collection
Diffractometer	Nonius KappaCCD diffractometer
Absorption correction	Gaussian (JANA2000; Petříček & Dušek, 2000)
T_min, T_max	0.137, 0.330
No. of measured, independent and observed [I > 3σ(I)] reflections	5499, 606, 454
R_int	0.064
(sin θ/λ)_max (Å⁻¹)	0.866

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.030, 0.037, 1.75
No. of reflections	606
No. of parameters	15
No. of restraints	3
Δρ_max, Δρ_min (e Å⁻³)	2.48, −3.60

Computer programs: KappaCCD Software (Nonius, 1998), DENZO and SCALEPACK (Otwinowski & Minor, 1997), coordinates taken from analogous clathrates-I (Reference?), JANA2000 (Petříček & Dušek, 2000), GRETEP (Laugier & Bochu, 2002).

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