81
Z. Kristallogr. NCS 219 (2004) 8 1 - 8 2
© by Oldenbourg Wissenschaftsverlag, München
Crystal structure of ytterbium lithium digermanide, YbLiGe2
Q.-X. Xie and R. Nesper*
ETH Hönggerberg-HCI, Laboratorium für Anorganische Chemie, Wolfgang-Pauli-Strasse 10, CH-8093 Zurich, Switzerland
Received February 11, 2004, accepted and available on-line March 29, 2004; CSD no. 409768
I
a bond angle of 103.25(6)°. Every Ge atom is coordinated by a
mono-capped trigonal cation prism, and the whole chain is
situated in puckered cation channels. YbLiGe2 can be formulated
as (Yb2+)(Li+)(Ge15~>2 according to the Zintl-Klemm concept
[3-5],
Like in other EAUTt2 (EA = Ca, Sr, Ba) compounds [2,6], the ji*
orbitals of the planar germanium chains are not fully occupied
leading to a double bond contribution which is also indicated by a
relatively short Ge—Ge bond distance [7]. The chains are ecliptically stacked in pairs with the shortest distance about 4.4 A, an interaction between n* states can occur leading to the enhanced
one-dimensional metallic conductivity. In YbLiGe2 ytterbium
coordinates nine germanium atoms of three chains and is almost
in the centre of a trigonal Ge6 prism. Every lithium atom is in the
centre of a mono-capped Ge4 tetrahedron, also coordinated by
three anion chains.
ß
Table 1. Data collection and handling.
dark grey plate, size 0.06 x 0.08 x 0.12 mm
Mo Ka radiation (0.71073 A)
466.87 cm - 1
Diffractometer, scan mode:
Bruker SMART CCD, to
68.24°
20max:
N(hkl)measured, N(hkl)unique: 4837,710
Criterion for /obs, N(hkl)p:
/obs > 2 af/obsj, 566
N(param}nTiaei-22
Programs:
SADABS [8], SHELXS-97 [9],
SHELXL-97 [10], ORTEP-3 [11]
Crystal:
Wavelength:
Abstract
Ge2LiYb, orthorhombic, Pnma (no. 62), a = 7.939(2) A,
b = 3.882(1) A, c = 10.524(3) A, V= 324.4 A3, Z = 4,
Rgt(F) = 0.030, wRretfF2) = 0.064, T= 293 K.
Source of material
YbLiGe2 was synthesized from a mixture of pure elements in
stoichiometric amounts via direct heating method in argon atmosphere up to 1173 K for 12 h. After cooling down at a rate of
20 K/h, the product was obtained as dark grey crystals with metallic lustre.
Discussion
Similar to EuLiGe2 [ 1 ], YbLiGe2 crystallizes in CaLi7"/2 (7Y=Si,
Ge) [2] structure. The Zintl anion is a one-dimensional chain in
&\\-trans conformation with a Ge—Ge distance of2.476(1) A and
Table 2. Atomic coordinates and displacement parameters (in A 2 ).
Atom
Site
Li(l)
4d
I/i*
0.489(2)
1/4
0.611(2)
0.018(3)
Table 3. Atomic coordinates and displacement parameters (in A2).
Atom
Site
X
y
z
f/n
Í/22
1/33
Í/12
Yb(l)
Ge(l)
Ge(2)
4c
4c
4c
0.13469(5)
0.1543(1)
0.2329(1)
1/4
1/4
1/4
0.36364(4)
0.6811(1)
0.06243(9)
0.0099(2)
0.0091(4)
0.0113(4)
0.0132(2)
0.0122(4)
0.0119(4)
0.0146(2)
0.0167(4)
0.0156(4)
0
0
0
Un
-0.0003(1)
0.0016(3)
-0.0018(3)
t/23
0
0
0
* Correspondence author (e-mail: nesper@inorg.chem.ethz.ch)
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82
YbLiGe2
Acknowledgment. This work was supported by the Swiss National Foundation.
References
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Akad. Nauk Ukr. 7 (1986) 76-78.
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Wiley-VCH, Weinhein 2003.
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11. Farrugia, L. J.: ORTEP-3 for Windows - a version of ORTEP-m with a
Graphical User Interface (GUI). J. Appi. Crystallogr. 30 (1997) 565.
Unauthenticated
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