The first reduced rare earth halide with a group 11 element as interstitial: La3I3Au

Article abstract of DOI:10.1002/zaac.200400322

The title compound was synthesized from La, LaI₃ and Au under Ar atmosphere in the temperature range 850-950°C. It crystallizes in the cubic space group I4₁32 with lattice constant a = 12.661(2) A. The structure features Au-centered helical octahedron chains arranged in all three directions with 90 degree turns. It is the first reduced rare earth halide with a group 11 interstitial. It is very air and moisture sensitive, and produces crimson-colored Au precipitate similar to Gold Purple of Cassius upon reaction with water or ethanol.

Full text of DOI:10.1002/zaac.200400322

The First Reduced Rare Earth Halide with a Group 11 Element as Interstitial:
La3I3Au
Hansjürgen Mattauscha,*, Chong Zhengb, Lorenz Kienlea, and Arndt Simona
a Stuttgart, Max-Planck-Institut für Festkörperforschung, Heisenbergstrasse 1
b DeKalb, IL USA, Department of Chemistry and Biochemistry, Northern Illinois University
Received July 27th, 2004.
Professor Martin Jansen zum 60. Geburtstag gewidmet
Abstract. The title compound was synthesized from La, LaI3 and
Au under Ar atmosphere in the temperature range 850-950 °C. It
crystallizes in the cubic space group I4132 with lattice constant a ϭ
very air and moisture sensitive, and produces crimson-colored Au
precipitate similar to Gold Purple of Cassius upon reaction with
water or ethanol.
˚
12.661(2) A. The structure features Au-centered helical octahedron
chains arranged in all three directions with 90 degree turns. It is
the first reduced rare earth halide with a group 11 interstitial. It is
Keywords: Lanthanum; Gold; Aurides; Nanoparticles
Das erste reduzierte Seltenerdhalogenid mit einem Interstitialatom der Gruppe 11:
La3I3Au
Inhaltsübersicht. La3I3Au wird aus La, LaI3 und Au in Ar-Atmo-
sphäre bei Temperaturen zwischen 850 °C und 950 °C in Ta-Ampul-
len dargestellt. Es kristallisiert kubisch in der Raumgruppe I4132
mit a ϭ 12.661(1) A. In der Struktur liegen Au-zentrierte La6-
Oktaeder vor, die helikal über jeweils drei gemeinsame Oktaeder-
kanten dreidimensional verknüpft sind. Es ist das erste reduzierte
Seltenerdhalogenid mit einem Interstitialatom der 11. Neben-
gruppe. La3I3Au ist extrem empfindlich gegen Feuchtigkeit und
hydrolisiert zu einem purpurfarbenen Niederschlag von Au ver-
gleichbar mit Cassius’schem Goldpurpur.
˚
Introduction
Experimental Section
Reduced rare earth metal halides can include into their
structures numerous types of atoms at the centers of rare
earth metal octahedra or trigonal prisms. The interstitials
can be the main group elements H, B, Al, Ga, C, Si, N, P,
As, Sb or the transition metals Mn, Fe, Co, Ni, Ru, Os, Rh,
Ir and Pt [1Ϫ12]. However, compounds with group 11 or
12 transition metal interstitials have not been reported so
far. Previous computational analysis suggested that there is
an energy gap in the molecular orbitals (MO) of the metal
polyhedron cluster. Filling the MO’s above the gap would
destabilize the cluster structure [8, 9]. The maximum num-
ber of electrons that can be put into the cluster MO’s with-
out destabilizing a M6X18 cluster was suggested to be 18.
Compounds with group 11 or 12 transition metal inter-
stitials would exceed this limit. In this contribution, we re-
port the synthesis and structure of the first reduced rare
earth halide with Au as the interstitial. The electronic struc-
ture of the compound is also analyzed.
Synthesis. La metal (sublimed, 99.99 %; Alfa-Aesar, small pieces),
LaI3 and Au (99.99 %; Alfa-Aesar, small pieces) were used as start-
ing materials. LaI3 was obtained from the reaction of La metal with
I2 at 800 °C. The product LaI3 was purified twice by sublimation
in a Ta tube before being used. All handlings were carried out un-
der Ar atmosphere either in a glove box or through the Schlenk
technique.
The mixtures (ca. 1.5 g) of the starting materials were arc-sealed in
Ta tubes under Ar atmosphere. The Ta tubes were then sealed in-
side silica ampoules under a vacuum of ca. 10Ϫ2 mbar. The prep-
aration details are summarized in Table 1. After the reaction, the
tubes were opened under Ar atmosphere, and many golden irregu-
lar polyhedron crystals could be observed. The yield was at least
greater than 80 %, in 5 Յ 90 % as estimated from the samples’
Guinier pattern. EDX analysis of these single crystals, using a
Tescan scanning electron microscope equipped with an Oxford
EDX detector, showed an atomic percentage of approximately
44 %, 42 % and 14 % for La, I and Au, with a standard deviation
of 5 % respectively. The compound is extremely air and moisture
sensitive. On contact with water, methanol or ethanol, it decom-
poses instantaneously, producing bright crimson-colored Au col-
loid similar to that of Gold Purple of Cassius [17, 18]. The reaction
also releases hydrogen gas, as expected from the electron balance.
Transmission electron microscope images (Figure 1) reveal that the
colloid particles are well ordered with average size of ca. 5 nm.
* Dr. Hj. Mattausch
Max-Planck-Institut für Festkörperforschung,
Heisenbergstr. 1
D-70569 Stuttgart
E-mail: Hj.Mattausch@fkf.mpg.de.
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Hj. Mattausch, C. Zheng, L. Kienle, A. Simon
Transmission Electron Microscopy. Electron microscopy studies
Structure Determination. The reaction product was ground to fine
powder under Ar atmosphere and sealed in a glass capillary for
phase identification by a modified Guinier technique [19] (CuKα1:
were performed with a Philips CM30ST (LaB6-cathode, 300 kV,
˚
resolution: 1.9 A). Fast Fourier Transforms (FFT) of high resolu-
˚
˚
tion micrographs were calculated with the software Digital Micro-
graph 3.6.1 (Gatan). EDX (Si-Li-Detector, Noran) was performed
with a nanoprobe (point analyses) and in the scanning mode (spec-
tral imaging).
Physical Property Measurement. A polycrystalline sample was
pressed into a pellet of ca. 500 mg in weight, 5 mm in diameter and
2 mm in thickness for conductivity measurement. The conventional
van der Pauw four-contact method was used. The measurement
was carried out under He-atmosphere in a Quantum Design PPMS
instrument in the temperature range 5 K to 300 K (Bϭ0T).
λ ϭ 1.54056 A; internal standard Si with a ϭ 5.43035 A; Fujifilm
BAS-5000 image plate system). Single crystals were transferred to
glass capillaries under Na-dried paraffin oil and sealed under Ar
atmosphere. They were first examined by the precession and Weis-
senberg techniques. The data of a number of chosen single crystals
with good reflection quality were collected on a Stoe IPDS dif-
fractometer. The structure was solved with direct methods using
the SHELXTL package [20]. Full matrix least square refinements
on F2 were carried out using the SHELXTL program [20]. During
the investigation, it was evident that a mixed occupation of Au and
I occurs at the center of the La6 octahedron. Therefore, many crys-
tals have been studied. The results of five representative ones are
summarized in Table 1. Our study shows that due to the mixed
occupation, the title compound has the nonstoichiometric formula
La3I3ϩxAu1Ϫx (0.04 Յ x Յ 0.16). The crystallographic information
including the fractional coordinates and selected bond lengths of
crystal 5 is listed in Tables 2 to 4.
Table 2 Crystal data and structure refinement (twin) for crystal 5
of La3I3Au.
Empirical formula
Formula weight
La3I3Au
994.40
Temperature
Wavelength
Crystal system
293(2) K
0.56086 A
cubic
˚
Space group
Unit cell dimensions
Volume, Z
I 41 3 2
a ϭ 12.661(2) A
˚
3
˚
2029.6(4) A , 8
6.509 g/cm3
Density (calculated)
Absorption coefficient
Theta range for data collection
Independent reflections
Completeness to theta ϭ 25.94°
Refinement method
Data / restraints / parameters
Goodness-of-fit on F2
Final R indices [I>2sigma(I)]
R indices (all data)
19.173 mmϪ1
3.11 to 25.94°.
683
99.3 %
Full-matrix least-squares on F2
683 / 0 / 16
0.769
R1 ϭ 0.0300, wR2 ϭ 0.0625
R1 ϭ 0.0446, wR2 ϭ 0.0643
2
*R1 ϭ ΣʈFoΗ Ϫ ΗFcʈ / ΣΗFoΗ; wR2 ϭ [Σ[w(Fo Ϫ Fc2)2] / Σ [w(Fo2)2]]1/2
Computational Study. The density of states (DOS), the crystal or-
bital overlap population (COOP) [21] curves and the band structure
were computed using both the tight-binding extended Hückel
method (EH) [22, 23] and the self-consistent linear muffin-tin or-
bital local density functional method with local density approxi-
Figure 1 a). Bright field image of the gold colloid particles. b).
Electron diffraction pattern. c). High resolution micrograph of gold
particles. d). FFT of c.
Table 1 Reaction temperature and crystal structure refinement for five representative crystals of La3I3Au.
Crystal
1
2
3
4
5
Reactant ratio La/Au/I
1/1/1
850
80
3/2/2
950
80
1/1/1
850
80
3/2/2
950
80
3.00/3.07/0.93
850
> 90
Reaction temperature /°Ca)
Yield in %
Byproduct
Au
Au
Au
Au
R1, wR2 (for idealized structure La3I3Au)
Occupation of Au/I at octahedron center in %
Occupation of I/Au at octahedron edge in %
Lattice parameter a/A
R1, wR2 (with mixed occupations)
Formula with mixed occupation
0.0231, 0.0651
89/11
97/3
12.632(1)
0.0205, 0.0531
La3I3.07Au0.93
0.0189, 0.0493
94/6
99/1
12.617(1)
0.0179, 0.0441
La3I3.03Au0.97
0.0509, 0.1771
61/39
92/8
12.647(1)
0.0313, 0.0804
La3I3.16Au0.84
0.0485, 0.1618
69/31
94/6
12.639(1)
0.0324, 0.0715
La3I3.12Au0.88
0.0390, 0.0991
73/27
97/3
12.661(1)
0.0300, 0.0625
La3I3.19Au0.81
˚
Average: La3I3ϩxAu1Ϫx (0.04 Յ x Յ 0.16)
a) Reaction length is ca. 13 days.
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The First Reduced Rare Earth Halide with a Group 11 Element as Interstitial
octahedra connect by their edges to a helical chain with a
Table 3 Atomic coordinates and equivalent isotropic displace-
2
ment parameters (A ϫ 103) for crystal 5 of La3I3Au. U(eq) is
90 degree turn. Each octahedron is linked to three other
octahedra through three non-adjacent edges in a three-
bladed propeller fashion. Thus there are three helical chains
originating from each La6 octahedron oriented along the
directions [ 1 0 0], [0 1 0] and [0 0 1]. As the structure
refinement shows, the Au atoms at the center of the La6
octahedron can be partially substituted by I atoms (up to
40 %). The substitution of the edge-sharing I atoms by Au,
however, is much less at a maximum of 10 %. The partial
substitution of the Au atoms (cluster center) by I and the I
atoms (cluster edges) by Au leads to a significant improve-
ment of the refinement (cf. Table 1). It can be seen from
Table 1 that there is only a small amount of substitution in
crystals 1 and 2, but a large one in crystals 3 to 5. The
substitution of the central cluster atoms by ligand atoms
has never been observed previously in the large isotypic
family Ln3X3Z. Nonetheless, it can be easily understood by
comparing the electron affinities of I and Au (Ϫ295.30 kJ/
mol vs. Ϫ222.73 kJ/mol) [27]. The Au/I substitution is also
an evident indication of the negative charge of Au ions in
the La6 cluster. Similar reactions are known for Au/Br sub-
stitution of alkali metal aurides in corresponding bromide
systems [28]. In crystal 5, the shortest La-La distance is
˚
defined as one third of the trace of the orthogonalized Uij tensor.
x/a
Ϫ18
y/b
z/c
U(eq)
Occ.
1
8
5
8
Au(1)
La(1)
I(1)
17(1)
19(1)
22(1)
17(1)
22(1)
0.73(1)
1
1
8
0.6113(1)
0.8866(1)
0.6387(1)
0.1366(1)
1
8
0.971(7)
0.27(1)
0.029(7)
1
8
5
8
I(1A)a)
Ϫ18
1
8
Au(1A)
0.8866(1)
0.1366(1)
a) A mixed occupancy model is used in the refinement.
˚
Table 4 Selected bond lengths/A for crystal 5 of La3I3Au.
Au(1)-La(1)#1
La(1)-I(1)#8
La(1)-I(1)#10
(8ϫ)
(4ϫ)
(4ϫ)
2.9963(6)
3.3319(8)
3.3578(7)
Symmetry transformations used to generate equivalent atoms:
#1 Ϫzϩ1/2,xϩ0,Ϫyϩ1 #8 yϪ1/2,zϩ1/2,xϩ1/2 #10 Ϫyϩ1,zϩ1/2,Ϫxϩ1/2
mation (LDA) as implemented in the Stuttgart-TB-LMTO-ASA
program [24]. Approximately 200 k-points in the irreducible wedge
of the Brillouin zone were used in the EH computation of the DOS
and COOP curves. More than 1000 k-points in the whole Brillouin
zone were generated in the LDA calculations. These k-points were
then reduced to the irreducible wedge of the Brillouin zone. Scalar
relativistic equation was used together with the von Barth-Hedin
local exchange-correlation potential function [24]. The EH para-
meters used in the computation are listed in Table 5. Because of the
possibility of a small nonstoichiometry parameter x (see crystals 1
and 2 in Table 1), the ideal La3I3Au structure assuming a full occu-
pation of Au at the La6 octahedron center was used in all calcu-
lations.
˚
along the shared octahedron edge at 3.98 A. The shortest
˚
La-Au and La-I bond lengths are all 3.00 A. Au atoms are
˚
separated at 3.98 A and thus not bonded to each other. The
6 corners of a La6Au octahedron are capped by I atoms at
˚
3.36 A, and the 9 non-connecting edges by I atoms at dis-
˚
tances from 3.33 to 3.36 A.
Au Colloids [29]
Table 5 Extended Hückel Parameters.
The composition and real structure of the colloids pro-
duced by hydrolysis of the title compound were analyzed
by transmission electron microscopy. As evidenced by
EDX, all particles consist of pure gold. Figure 1a displays
a bright field image of the particles covering a carbon sup-
port. The average size of the particles is approximately
5 nm. The electron diffraction pattern depicted in Figure 1b
was recorded on a selected area containing many particles.
The sharp Bragg reflections are located on concentric
circles as expected for aggregates of randomly orientated
but otherwise perfect single crystals. The diameters of the
circles correspond to the d-spacings of pure gold (dCu: d111
ϳ 2.36 A, d200 ϳ 2.04 A, d220 ϳ 1.44 A, d311 ϳ 1.23 A).
The crystalline nature of the particles was also supported
by high resolution transmission electron microscopy shown
in Figure 1c. The micrograph displays a periodic arrange-
ment of stripes within the particles corresponding to net
planes of gold. The d values measured from the FFT (Fig-
ure 1d) of Figure 1c can be assigned to the metrics of
pure gold.
a)
a)
Orbital
Hii (eV)
ζ1
ζ2
c1
c2
La
Au
I
6s
6p
5d
Ϫ7.67
Ϫ5.01
Ϫ8.21
2.14
2.08
3.78
1.381
2.794
0.7765
0.6442
0.4586
0.5356
6s
6p
5d
Ϫ10.92
Ϫ5.55
Ϫ15.07
2.602
2.584
6.163
5s
5p
Ϫ18.0
Ϫ12.7
2.679
2.322
a) Exponents and coefficients in a double ζ expansion of the d orbital.
˚
˚
˚
˚
Results and Discussion
Crystal Structure
The structure of the title compound is shown in Figure 2.
It belongs to a rather large family of compounds [25] with
the cubic structure type Ca3I3P [26]. The Au-centered La6
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of the [La6I18]10Ϫ fragment to a lesser extent.The t2g level is
pushed up slightly by the Au d orbitals lying below Ϫ15 eV.
The important consequence from the interaction is that
both the t1u and t2g sets are occupied. These levels are
characterized by La-La bonding and weak La-I antibond-
ing as shown by the MOOP [30] plot in Figure 4. Because
of the large electronegativity of Au (2.54 in Pauling scale)
and its low-lying d orbitals which are essentially core-states,
the t1u set is below the t2g HOMO, allowing 6 more elec-
trons to be accommodated. The 18 electron limit can there-
fore be extended to 24 in the case of Au. Figure 5 shows
the band structure calculated by the more accurate LDA
method for the three dimensional La3I3Au structure. Be-
cause of the sharing of three connecting edges in a La6Au
octahedron, one of the six orbitals is pushed up to higher
energy. Thus there are only 5 energy levels per 6 La atoms
near the HOMO corresponding to a 22 electron limit.
Consequently there are 10 bands between the Fermi level
and Ϫ1 eV, corresponding to the 12 La atoms in the primi-
tive cell employed in the LDA calculation.The Au 5d bands
in this figure are far below the Fermi level behaving like
core-states, as they are in the EH calculation.
The computed DOS and COOP for the three dimensional
La3I3Au structure using the EH method are shown in Fig-
ure 6. In Figure 6a, the states around Ϫ18 eV are the I 5s
orbitals followed by the Au 5d states near Ϫ15 eV. Near
Ϫ12 eV are the I 5p states which mix with the Au 6s orbital
around Ϫ11 eV. Between the Fermi level and Ϫ9 eV are the
La 5d t2g and t1u states. Figure 6b-e demonstrates that all
states below the Fermi level contribute to La-Au and La-
La bonding. Near the Fermi level the states are weakly La-
I antibonding. Additional electrons would occupy the La-I
antibonding levels.
Figure 2 The structures of La3I3Au showing only three La6 octa-
hedron helices originating from a center octahedron and running
in a, b and c directions with 90 degree turns.
Electronic Structure
The Au interstitial exists as AuϪ, similar to other auride
compounds such as CsAu [13], and Cs2RbAuO, Ca3AuN
reported by Jansen’s and Kniep’s research groups [14Ϫ16].
As the Au atoms are not bonded to each other in La3I3Au,
the charge state of the compound can be formulated as
(La3ϩ)3(IϪ)3AuϪႧ5eϪ, which means that the compound is
a metallic iodide auride. This corresponds to 5/3 skeleton
electrons per La. For a La6Au octahedron, this translates
to 6 ϫ 5/3 ϩ 12 ϭ 22 cluster electrons including the valence
electrons of the interstitial AuϪ, far exceeding the 18 elec-
tron limit [8, 9]. To understand the electronic structure of
the title compound, we computed the MO levels of an ideal-
ized La6I18Au octahedron with the EH method, using the
average La-La and La-I distances from the experimental
La3I3Au structure. To arrive at the 22 cluster electron
count, a Ϫ11 charge is added to the octahedron. These ad-
ditional 11 electrons, together with the 11 valence electrons
of the Au interstitial, sum to 22 cluster electrons for
[La6I18Au]11Ϫ. Figure 3 shows the MO levels as derived
from the two fragments [La6I18]10Ϫ and AuϪ. For clarity,
only the relevant frontier orbitals are depicted in the figure.
In this cluster, each La is coordinated to 6 ligands in an
octahedral environment. Thus its d orbitals are split to a
low-lying t2g set and a high eg set. The six La local t2g sets
combine to form 18 symmetry-adapted MO’s transforming
as 2t2g, t1g, t1u, t2u, eu and a2u. Of these orbitals, the relevant
t1u, t2g, eu and a2u sets are drawn on the left side of the
figure. The Au 6s orbital transforms as a1g and 6p as t1u,
thus they interact with the a1g and t1u sets of the [La6I18]10Ϫ
fragment. The Au 6s orbital is stabilized, so does the t1u set
An EH calculation using the La3I3Au structure with the
Au atom replaced by an I atom showed that all states below
the Fermi level contribute to La-I (at the center of the La6
octahedron) and La-La bonding. The La-I (at the edges
Figure 3 Interaction diagram of an idealized [La6I18Au]11Ϫ cluster
calculated with the EH method taken from the La3I3Au structure.
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The First Reduced Rare Earth Halide with a Group 11 Element as Interstitial
of the La6 octahedron) interactions, however, are weakly
antibonding. The weakly antibonding pattern comes from
the fact that three of the octahedron edges are shared and
not capped by the I ligands, thus reducing the antibonding
character between the La atoms and the I ligands. This can
be one of the reasons that the center Au atoms can be par-
tially substituted by I atoms.
Figure 4 MOOP diagram of the molecular orbitals concentrated
on the La atoms calculated with the EH method for an idealized
[La6I18Au]11Ϫ octahedron cluster taken from the La3I3Au structure.
The MOOP is summed over for all the La-La edges in the octahe-
dron.
Figure 5 Band structure calculated with the LDA method for the
La3I3Au structure.Primitive cell is used instead of the body-cente-
red conventional cell for clarity.
Figure 6 DOS and COOP calculated with the EH method for
La3I3Au. a). DOS.The solid line is the total DOS, the dashed line
the integrated La DOS, and the shaded area is the contribution
from La. The vertical dashed line indicates the Fermi level.The
characteristic peaks are indicated by the arrows. bϪe). COOP cur-
ves for representative bonds in La3I3Au. The ϩ region is bonding
area and the Ϫ region antibonding area. The bond type, its di-
stance (d) and integrated overlap population (op) to the Fermi level
are indicated in the panel.
Physical Properties
The resistivity of La3I3Au measured in the temperature
range 5 K to 300 K shows a metallic behavior. It exhibits a
strictly linear temperature dependence between 50 K and
280 K. The metallic nature of the compound is expected
from the Zintl-Klemm electron partitioning of
(La3ϩ)3(IϪ)3AuϪႧ5e-. It is also a consequence of the filling
of the La d states which are delocalized along the helical
octahedron chains. Because of the delocalization, the La
d states span a region near the Fermi level as shown in
Figure 6.
To summarize, the above computational analysis demon-
strates that when the interstitial metal d orbital energy is
low compared to the ligand orbital energy levels, the limit
of the number of cluster electrons can be extended to 24.
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Hj. Mattausch, C. Zheng, L. Kienle, A. Simon
Acknowledgment. We thank R. Eger for the sample preparation, V.
Duppel for the electron microscopy, E. Brücher for the resistivity
measurement and C. Kamella for the drawing of the pictures. CZ
acknowledges the support by NSF through grants DMR-9704048
and CHE-9974760, and by the Max-Planck-Gesellschaft which
made his visit at MPI possible.
[11] G. Meyer, M. S. Wickleder, in: Handbook on the Physics and
Chemistry of Rare Earths, Chapter 177, Vol. 28, K. A. Gschne-
idner Jr. and L. Eying (eds), Elsevier Science Publishers, Am-
sterdam-London-New York-Tokyo, 2000, p. 53.
[12] J. D. Corbett, J. Chem. Soc. Dalton Trans. 1996, 575.
[13] G. Kienast, J. Verma, W. Klemm, Z. Anorg. Allg. Chem. 1961,
310, 143.
[14] A. V. Mudring, M. Jansen, J. Daniels, S. Krämer, M. Mehring,
J. P. Ramalho, A. H. Romero, M. Parrinello, Angew. Chem.
2002, 114, 128; Angew. Chem. Int. Ed. 2002, 41, 120.
[15] A. V. Mudring, M. Jansen, Z. Kristallogr. NCS 2001, 216, 325.
[16] J. Jäger, D. Stahl, P. C. Schmidt, R. Kniep, Angew. Chem.
1993, 105, 738; Angew. Chem. Int. Ed. Engl. 1993, 32, 709.
[17] Gmelins Handbuch der Anorganschen Chemie 1954, 62, 399.
[18] A.-V. Mudring, J. Nuss,U. Wedig, M. Jansen, J. Solid State
Chem. 2000, 155, 29.
[19] A. Simon, J. Appl. Crystallogr. 1970, 3, 11.
[20] G.M. Sheldrick, SHELXTL. Version 5.1, Bruker Analytical
Instruments Inc., Madison, Wisconsin, 1997.
[21] S. D. Wijeyesekera, R. Hoffmann, Organometallics 1984, 3,
949.
Supporting Information Available: Further details of the crystal
structures can be obtained from Fachinformationszentrum
Karlsruhe, D-76334 Eggenstein-Leopoldshafen, Germany, or via
e-mail crysdata@fiz-karlsruhe.de free of charge upon quoting the
numbers CSD-414264.
References
[1] A. Simon, Hj. Mattausch, G. J. Miller, W. Bauhofer, R. K.
Kremer, in: Handbook on the Physics and Chemistry of Rare
Earths, Vol. 15, K. A. Gschneidner Jr. and L. Eying (eds),
Elsevier Science Publishers, Amsterdam-London-New York-
Tokyo, 1991, p. 191.
[2] Hj. Mattausch, O. Oeckler, A. Simon, Inorg. Chim. Acta 1999,
289, 174.
[3] Hj. Mattausch, A. Simon, Angew. Chem. 1998, 110, 498; An-
gew. Chem. Int. Ed. 1998, 37, 499.
[4] E. Warkentin, A. Simon, Rev. Chim. Miner. 1983, 20, 488.
[5] D. Nagaki, A. Simon, H. Borrmann, J. Less-Common Met.
1989, 156, 193.
[22] M. H. Whangbo, R. Hoffmann, R. B. Woodward, Proc. R.
Soc. London 1979, A366, 23.
[23] R. Hoffmann, J. Chem. Phys. 1963, 39, 1397.
[24] O. K. Andersen, O. Jepsen, Phys. Rev. Lett. 1984, 53, 2571.
[25] C. Zheng, O. Oeckler, Hj. Mattausch, A. Simon, Z. Anorg.
Allg. Chem. 2001, 627, 2151.
[26] C. Hamon, R. Marchand, Y. Laurent, J. Lang, Bull. Soc. Fr.
[6] P. K. Dorhout, M. W. Payne, J. D. Corbett, Inorg. Chem. 1991,
30, 4960.
[7] R. Llusar, J. D. Corbett, Inorg. Chem. 1994, 33, 849.
[8] T. Hughbanks, G. Rosenthal, J. D. Corbett, J. Am. Chem. Soc.
1986, 108, 8289.
´
Mineral. Cristallogr. 1974, 97, 6.
[27] H. Hotop, W. C. Lineberger, J. Phys. Chem., Ref. Data 1975,
4, 539.
[28] R. Wormuth, R. W. Schmutzler, Thermochim. Acta 1990,
160, 97.
[9] T. Hughbanks, J. D. Corbett, Inorg. Chem. 1988, 27, 2022.
[10] T. Hughbanks, J. D. Corbett, Inorg. Chem. 1989, 28, 631.
[29] D. Beischer, F. Krause, Naturwissenschaften 1937, 25, 825.
[30] C. Mealli, D. M. Proserpio, J. Chem. Educ. 1990, 67, 399.
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