ζ . Kristallogr. N C S 2 1 3 (1998) 6 7 9
© by R. Oldenbourg Verlag, München
C r y s t a l s t r u c t u r e o f t h e c l a t h r a t e ß - B a s G a i e S n a o
H . G . v o n S c h n e r i n g , W . C a r r i l l o - C a b r e r a , R . K r ö n e r , E . - M . P e t e r s , K . P e t e r s
Max-Planck-lnslitut für Festkörperforschung, Heisenbergstraße 1, D-70569 Stuttgart. Germany a n d R . N e s p e r
ΕΤΗ Zürich. Laboratorium fur Anorganische Chemie, Universitätsstr. 6, CH-8092 Zürich, Switzerland Received March 4, 1998, transferred to Ist update of database ICSD in 1999, CSD-No. 409265
ß-BasGaiöSnao b e l o n g s to the clathrate-I structure cP5A. T h e refínement of the site occupancies results in a complete occupa- t i o n of t h e c a v i t i e s by B a a t o m s a n d in t h e c o m p o s i t i o n Ba8Ga/,Sni36-n with η = 16.5 ± 0.9. Bond lengths in the E46 net ( f i g u r e ) : d\ = 2.675(2) Â, d 2 = 2.746(1) Â, Л = 2.785(1) Â, dA = 2.691(1) Â. (No indication for a potassium content).
Obviously, BasGaieSnso exists in two modifications, namely α (c/54, see ref. 2) and β (cP5A, clathrate-I). The stability ranges of the two phase are not known, but both belong to the Zintl phases.
BagGaiöSnaa cubic, Ρηβη (No. 223), a =11.744(2) Â, V=1620 Â^, Z = l , R(F) =0.030, R^F) =0.029.
Table 1. Parameters used for the X-ray data collection
Crystal: grey block, size 0.2 χ 0.1S χ 0.1 mm Wavelength: Mo Ka radiation (0.71069 A) μ: 226.6 cm-'
Difliactometer: Nicolet R3m/V Scan mode: ω '^nuasurement'· 293 К
гвша»: 55°
щтш,и,ие: 364 Criterion for/о: /ο>3σ(/ο) ìi{param)refimd. 22
Program: SHELXTL-plus
Source of material: The compound was obtained as one of the p r o d u c t s w i t h t h e c h e m i c a l v a r i a t i o n o f KsGasSnss a n d BasGaiôSnaa which represents the difíerent clathrate structures cP54 and c / 5 4 (see refs. 1, 2). Mixtures of the elements were sealed in Nb/Ta capsules under Ar, heated up to 1270 К (3 h), annealed at 9 7 0 К (2-3 d), and cooled down. The grey brittle compound is stable in air and against dilute acids and bases.
Table 2. Final atomic coordinates and displacement parameters (in Â^)
References
1. Kroner, R.: Zintl-Phasen der Alkalimetalle und des Bariums mit Clathrat- struknir. Dissertation, Universität Smttgart, 1989.
2. Eisenmann В.; Schäfer H.; Weiss Α.: Die Verbindungen А8°В1б'°Взо'^
(A° = Sr, Ba; B™ = Al.Ga; В"^ = Si, Ge, Sn) und ihre Käfigstrukturen. J.
Less Common Met. 118 (1986) 43-55.
3. Sheldrick, G. M.: Program Package SHELXTL-plus. Release 4.1.
Siemens Analytical X-Ray Instruments Inc., Madison (WI53719), USA 1990.
Atom Site Occ. X У ζ Un U21 Uì3 Un Un £/23
Bai 2a 0 0 0 0.0286(5) 1/11 Uu 0 0 0
Ba2 24,· 0.25 1/4 0.5244(3) у+1/2 0.043(1) 0.090(3) U72 0.0127(9) -{/12 -0.029(3)
El(Ga) 6c 0.73 1/4 0 1/2 0.0261 0.0252 ί/22 0 0 0
El(Sn) 6c 0.27(2) 1/4 0 1/2 0.0261(8) 0.0252(6) ί/22 0 0 0
E2(Ga) 16/ 0.35 0.18424 X χ 0.0254 Un Uu -0.0007 Un Un
E2(Sn) I6Í 0.65(2) 0.18424(4) X χ 0.0254(4) Un Uu -0.0007(2) Un Un
E3(Ga) 24k 0.27 0 0.31229 0.11855 0.0277 0.0242 0.0233 0 0 -0.0014
E3(Sn) 24k 0.73(2) 0 0.31229(5) 0.11855(5) 0.0277(4) 0.0242(4) 0.0233(4) 0 0 -0.0014(2)
