Isolated and edge-sharing interstitially stabilized metal tetrahedra {M4Z} in La4ZBr7, M9Z 4I16, and BaM4Z2I8 (M = La,Ce). The nature of Z

Article abstract of DOI:10.1002/zaac.200600131

Metallothermic reductions of LaBr₃, LaI₃ and CeI ₃ with barium metal resulted in single crystals of La ₄ZBr₇, M₉Z₄I₁₆ and BaM₄Z₂I₈ (M = La,Ce) as by-products, subject to apparently ubiquitous oxygen and/or nitrogen (= Z) impurities. The crystal structure of La₄ZBr₇ (1, orthorhombic, Pnma, Z = 4, a = 1212.4(1), b = 1404.8(2), c = 804.7(1) pm, R ₁ = 0.0358 for I>2σI with N:O = 0.91:0.09) is determined by isolated {La₄Z} tetrahedra surrounded by and connected through bromide ligands. In the crystal structure of Ce₉Z₄I ₁₆ (2, orthorhombic, Fddd, Z = 8, a = 890.0(1), b = 2264.1(2), c = 4279.5(4) pm, R₁ = 0.0262 for I>2σI with N:O = 0.75:0.25), {Ce₄Z} tetrahedra are connected to {Ce_4/2Z} chains via common edges and further to layers by iodide ligands. The layers are stacked and connected via the ninth cerium atom according to Ce[{Ce_4/2Z}I ₄]₄. Similar {La_4/2Z} chains and BaI _8/4 chains run perpendicularly to each other and are connected via common iodide ions in the crystal structure of BaLa₄Z ₂I₈ = Ba₂[{La_4/2Z}I ₄]₄ (3, monoclinic, C2/c, Z = 4, a = 897.5(1), b = 2162.4(3), c = 1229.3(2), β = 110.32(1)°, R₁ = 0.0261 for I>2σI with N:O = 0.54:0.46). The nature of the interstitial Z, oxygen and/or nitrogen, is evaluated.

Full text of DOI:10.1002/zaac.200600131

DOI: 10.1002/zaac.200600131
Isolated and Edge-Sharing Interstitially Stabilized Metal Tetrahedra {M4Z} in
La4ZBr7, M9Z4I16, and BaM4Z2I8 (M ؍ La,Ce). The Nature of Z
Niels Gerlitzki, Stefanie Hammerich, Ingo Pantenburg, and Gerd Meyer*
Köln, Institut für Anorganische Chemie der Universität
Received May 8th, 2006.
Abstract. Metallothermic reductions of LaBr3, LaI3 and CeI3 with
barium metal resulted in single crystals of La4ZBr7, M9Z4I16 and
BaM4Z2I8 (M ϭ La,Ce) as by-products, subject to apparently ubi-
quitous “oxygen” and/or “nitrogen” (ϭ Z) impurities. The crystal
structure of La4ZBr7 (1, orthorhombic, Pnma, Z ϭ 4, a ϭ
1212.4(1), b ϭ 1404.8(2), c ϭ 804.7(1) pm, R1 ϭ 0.0358 for I>2σI
with N:O ϭ 0.91:0.09) is determined by isolated {La4Z} tetrahedra
surrounded by and connected through bromide ligands. In the cry-
stal structure of Ce9Z4I16 (2, orthorhombic, Fddd, Z ϭ 8, a ϭ
890.0(1), b ϭ 2264.1(2), c ϭ 4279.5(4) pm, R1 ϭ 0.0262 for I>2σI
with N:O ϭ 0.75:0.25), {Ce4Z} tetrahedra are connected to
{Ce4/2Z} chains via common edges and further to layers by iodide
ligands. The layers are stacked and connected via the ninth cerium
atom according to Ce[{Ce4/2Z}I4]4. Similar {La4/2Z} chains and
BaI8/4 chains run perpendicularly to each other and are connected
via common iodide ions in the crystal structure of BaLa4Z2I8
ϭ
Ba2[{La4/2Z}I4]4 (3, monoclinic, C2/c, Z ϭ 4, a ϭ 897.5(1), b ϭ
2162.4(3), c ϭ 1229.3(2), β ϭ 110.32(1)°, R1 ϭ 0.0261 for I>2σI
with N:O ϭ 0.54:0.46). The nature of the interstitial Z, oxygen
and/or nitrogen, is evaluated.
Keywords: Lanthanum; Cerium; Reduced halides; Crystal structure
Introduction
that emerged were SrLaI4 and BaLaI4 [11], subsequently
amended by further AIIMI4-type iodides (A
ϭ
The metallothermic reduction of rare-earth metal trihalides,
MX3, with electropositive metals such as potassium was
used by Wöhler in 1828 to produce metallic yttrium for the
first time [1]. It was further explored roughly a century later
by Zintl [2] and Klemm [3] to prepare all of the rare-earth
metals. This synthetic procedure has been applied exten-
sively over the past two decades [4Ϫ7] to explore the chem-
istry that happens under way between the trivalent state and
the metal, including the introduction of interstitials Z to
stabilize tetrahedral, trigonal-bipyramidal and octahedral
rare-earth metal clusters. Quite recently, sodium has been
used to reduce both LaI2 and LaI3, thereby establishing a
new route to the unique LaI [8] which had been obtained
via a conproportionation reaction roughly a decade before
for the first time [9].
Sr,Ba,Nd,Sm,Eu; M ϭ La,Ce) with the same structure [12],
and Ba6Pr3I19 [13]. For an overview see [14].
Reactions of LaI3 and CeI3 as well as LaBr3 with barium
metal resulted, among other products, as by-products in
five new compounds with excess electrons, La4ZBr7,
M9Z4I16 and BaM4Z2I8 (M ϭ La,Ce), respectively [15]. The
nature of the interstitial Z cannot be clearly stated but is
evaluated by structure refinements.
Experimental Details
Lanthanum tribromide and triiodide, LaBr3 and LaI3, and cerium
triiodide, CeI3, were prepared according to literature procedures,
LaBr3 via the ammonium-bromide route from La2O3 and (NH4)Br
[16], LaI3 and CeI3 from the elements [17]. For the iodides, to allow
for a faster reaction at fairly low temperatures, a small („catalytic“)
amount of (NH4)I was added, for example 1.45 mg ammonium
iodide together with 1.40 g cerium metal and 4.20 g iodine. The
temperature program was as follows: 100 °C (25 °C/h), 150 °C
(5 °C/h), 185 °C (10 °C/h), remain there for 12 h, 250 °C (10 °C/h),
9 h, 25 °C (20 °C/h). The crude products of all three halides were
sublimed in high vacuum. All handling of the starting materials
and the products was performed under dry box conditions (argon,
MBraun, Garching).
Recently, we have added alkaline-earth metals to our col-
lection of reductants [10]. A number of reduced rare-earth
metal halides that had been characterized previously such
as LaI2, Pr2I5, and Sc0.87I2 were obtained as single crystals
by the reduction of the respective triiodides with strontium,
or LaI2 by reduction of LaI3 with barium. New iodides
* Prof. Dr. G. Meyer
Institut für Anorganische Chemie
Universität zu Köln
Greinstraße 6
D-50939 Köln
E-Mail: gerd.meyer@uni-koeln.de
www.gerdmeyer.de
LaBr3, LaI3 and CeI3, respectively, and barium metal (previously
distilled) were filled in 2:1 molar ratios in tantalum containers
which were sealed by He-arc welding and jacketed in silica am-
poules under reduced pressure. The reaction mixtures were brought
to temperatures of 850 °C (1) and 780 °C (2, 3), respectively, kept
there for ten hours (1, 2) and 240 hours (3), and cooled with
2024
 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
Z. Anorg. Allg. Chem. 2006, 632, 2024Ϫ2030

Interstitially Stabilized Metal Tetrahedra
Table 1 Crystal data and structure refinement parameters for
La4ZBr7 (1), Ce9Z4I16 (2) and BaLa4Z2I8 (3).
Table 2 Atomic coordinates and equivalent isotropic displace-
ment parameters for La4ZBr7 (1).
Atom
Site
x
y
z
Ueq*
1
2
3
La1
La2
La3
Br1
Br2
Br3
Br4
O1
(8d)
(4c)
(4c)
(8d)
(8d)
(4c)
(8d)
(4c)
(4c)
0.34002(5)
0.16644(7)
0.55736(7)
0.36852(9)
0.67165(9)
0.4398(1)
0.0900(1)
0.728(1)
0.11614(4)
0.88197(7)
0.53559(9)
0.53160(9)
0.5137(1)
0.3036(1)
0.1452(2)
0.6623(1)
0.674(1)
0.0185(2)
0.0173(2)
0.0187(2)
0.0204(2)
0.0224(2)
0.0215(3)
0.0251(3)
0.020(3)
empirical formula
La4N0.91O0.09Br7 Ce9N3.01O0.99I16
BaLa4N1.07O0.93I8
1738.05
1
/
/
formula mass /g molϪ1 1129.20
3349.48
4
1
4
data collection
diffractometer
radiation
temperature /K
index range
0.11236(7)
STOE IPDS I
STOE IPDS II
STOE IPDS I
0.38996(7)
1
Mo-Kα (graphite monochromator, λ ϭ 71.073 pm)
/
4
293(2)
293(2)
293(2)
0.05252(7)
1
/
/
Ϫ14 Յ h Յ 14
Ϫ17 Յ k Յ 18
Ϫ10 Յ l Յ 10
0° Յ ϕ Յ 200°
Ϫ11 Յ h Յ 11
Ϫ28 Յ k Յ 28
Ϫ54 Յ l Յ 54
0° Յ ω Յ 180°; ψ ϭ 0° 0° Յ ϕ Յ 200°
0° Յ ω Յ 82°; ψ ϭ 90°
Ϫ11 Յ h Յ 11
Ϫ28 Յ k Յ 28
Ϫ14 Յ l Յ 14
4
1
N1
0.728(1)
0.674(1)
0.020(3)
4
* Ueq is defined as one-third of the trace of the orthogonalized tensor.
rotation angle range
increment
no. of images
∆ϕ ϭ 2°
100
∆ω ϭ 2°
131
∆ϕ ϭ 2°
100
Table 3 Atomic coordinates and equivalent isotropic displace-
ment parameters for Ce9Z4I16 (2).
exposure time /min
detector distance /mm
2·θ range /deg
total data collected
unique data
5
60
8
120
1.9 Ϫ 54.8
23456
2424
5
60
3.8 Ϫ 56.3
12183
1519
3.8 Ϫ 56.3
10620
2526
Atom
Site
x
y
z
Ueq*
Ce1
Ce2
Ce3
I1
I2
I3
I4
O1
N1
(32h)
(32h)
(32h)
(32h)
(32h)
(32h)
(32h)
(32h)
(32h)
0.97515(5)
0.48004(2)
0.03919(1)
Ϫ0.01839(1)
Ϫ1/8
Ϫ0.08514(1)
0.00316(1)
0.05835(1)
Ϫ0.08428(1)
Ϫ0.0106(1)
Ϫ0.0106(1)
0.0226(1)
0.0213(1)
0.0254(2)
0.0295(1)
0.0281(1)
0.0293(1)
0.0307(1)
0.020(2)
observed data
Rmerg
absorption correction
1210
0.0775
1965
0.0620
2184
0.0385
0.68794(5)
0.40332(2)
7
3
/
/
8
8
numerical, after crystal shape optimization [20]
0.58401(6)
0.67433(6)
0.66265(6)
0.74116(7)
0.9371(7)
0.9371(7)
0.33014(2)
0.54633(2)
0.40428(2)
0.48678(2)
0.4363(2)
0.4363(2)
transmission min / max 0.0217 / 0.0613
0.0488 / 0.1515
0.0622 / 0.1159
crystallographic data
crystal size /mm3
colour
0.3·0.1·0.1
black
column
orthorhombic
Pnma (no. 62)
1212.4(1)
1404.8(2)
804.7(1)
0.5·0.2·0.2
dark red
column
orthorhombic
Fddd (no. 70)
890.0(1)
0.3·0.1·0.1
orange
0.020(2)
habit
column
monoclinic
C2/c (no. 15)
897.5(1)
2162.4(3)
1229.3(2)
110.32(1)
2237.3(5)
4
crystal system
space group
a /pm
b /pm
c /pm
* Ueq is defined as one-third of the trace of the orthogonalized tensor.
2264.1(2)
4279.5(4)
Table 4 Atomic coordinates and equivalent isotropic displace-
ment parameters for BaLa4Z2I8 (3).
β /°
volume /106 pm3
Z
1370.5(3)
4
5.473
32.579
1920
8623.0(2)
8
5.160
20.751
11192
ρcalc /g cmϪ3
5.160
20.228
2892
Atom
Site
x
y
z
Ueq*
µ /mmϪ1
F(000)
Ba
La1
La2
I1
I2
I3
I4
O1
N1
(4e)
(8f)
(8f)
(8f)
(8f)
(8f)
(8f)
(8f)
(8f)
0
0.26779(3)
0.46376(2)
0.57851(2)
0.48855(2)
0.61884(2)
0.33727(2)
0.32314(2)
0.5213(3)
0.5213(3)
Ϫ1/4
0.0263(2)
0.0159(1)
0.0175(1)
0.0238(1)
0.0244(1)
0.0275(1)
0.0341(2)
0.023(2)
0.28581(4)
0.49601(4)
Ϫ0.12605(5)
0.25904(5)
0.22797(6)
0.26347(6)
0.5018(6)
0.5018(6)
0.19704(3)
0.03484(3)
0.09130(4)
0.19692(4)
0.02499(5)
0.35039(5)
Ϫ0.1259(5)
Ϫ0.1259(5)
structure analysis and
refinement*
structure
determination
no. of variables
R indexes [I>2σI]
SIR-92 [21] and SHELX-97 [18]
63
69
71
R1 ϭ 0.0358
wR2 ϭ 0.0889
R1 ϭ 0.0477
wR2 ϭ 0.0935
1.036
R1 ϭ 0.0262
wR2 ϭ 0.0592
R1 ϭ 0.0391
wR2 ϭ 0.0625
0.988
R1 ϭ 0.0261
wR2 ϭ 0.0643
R1 ϭ 0.0333
wR2 ϭ 0.0664
0.999
0.023(2)
R indexes (all data)
* Ueq is defined as one-third of the trace of the orthogonalized tensor.
goodness of fit (Sall
)
largest difference map
hole / peak /e 10Ϫ6pmϪ3 Ϫ1.503 / 1.528
Deposition number [24] ICSD-416395
Ϫ1.222 / 2.899
ICSD-416396
Ϫ1.525 / 2.034
ICSD-416397
the single crystals were transferred to a single-crystal X-ray dif-
fractometer (Stoe Image Plate Diffraction System, IPDS I and II)
to collect complete intensity data sets at ambient temperature.
R1 ϭ Σ ʈFoΗϪΗFcʈ / Σ ΗFoΗ, wR2 ϭ [Σ w (ΗFoΗ2ϪΗFcΗ2)2 / Σ w (ΗFoΗ2)2]1/2, S2 ϭ [Σ w
(ΗFoΗ2ϪΗFcΗ2)2 / (n-p)]1/2, with w ϭ 1 / [σ2 (Fo)2 ϩ (0.0589·P)2 ϩ 0.3976·P] for (1), w ϭ
1 / [σ2 (Fo)2 ϩ (0.0374·P)2] for (2) and w ϭ 1 / [σ2 (Fo)2 ϩ (0.0456·P)2] for (3) were
Structure solution and refinement was performed with the pro-
grams SIR-92 (direct methods) [21] and SHELXL-97 [18],
scattering factors were from International Tables for X-ray Crys-
tallogaphy, Vol C [19]. Data corrections were carried out for Lor-
entz and polarization factors and absorption (numerical with the
aid of the programs X-RED and X-SHAPE, Stoe, Darmstadt, 1994
[20]). For crystal data, structure refinement parameters and atomic
coordinates for La4ZBr7 (1), Ce9Z4I16 (2) and BaLa4Z2I8 (3) see
Tables 1Ϫ4, for La9Z4I16 (4) and BaCe4Z2I8 (5) see refs. [22] and
[23]. Further information may be obtained according to ref. [24].
2
P ϭ (Fo ϩ 2Fc2) / 3. Fc* ϭ k Fc [1ϩ0,001·ΗFcΗ2 λ3 / sin(2θ)]Ϫ1/4
.
1 °C/h to 400 °C (1), 1 °C/h to 500 °C for (2, 3), after which they
were further cooled to ambient temperature with 10 °C/h (1),
100 °C/h (2, 3).
The product of the 2LaBr3 ϩ Ba reaction contained, except for
LaBr3 and some BaBr2, a few black single crystals of La4ZBr7. The
product of the 2LaI3 ϩ Ba and 2CeI3 ϩ Ba reactions contained,
except for BaLaI4 and BaCeI4 as the main products, some crystals
of different habitus of M9Z4I16 (black) and BaM4Z2I8 (orange),
M ϭ La, Ce. Some crystals of both products were selected under
a microscope in a dry box and sealed in thin-walled glass capillaries.
After their quality had been checked by Laue diffraction patterns,
Results and Discussion
Ubiquitous oxygen (oxide) or nitrogen (nitride) impurities
present in the starting materials (LaBr3, LaI3, CeI3 and bar-
Z. Anorg. Allg. Chem. 2006, 2024Ϫ2030
 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
www.zaac.wiley-vch.de
2025

N. Gerlitzki, S. Hammerich, I. Pantenburg, G. Meyer
ium metal in the present case), in the reaction container
(tantalum) or as water on the surface of the silica jacket
(which could react with the tantalum container with oxygen
slowly diffusing through the wall), often react with halide
melts, even under reducing conditions. Oxides or oxide/
nitride-halides are the reaction products, frequently appear-
ing as a few single crystals.
During the years we have observed single crystals of B-
type Sm2O3 and of C-type Yb2O3 and Sc2O3 [25], NdOCl
and GdOCl [26], for example, with trivalent rare-earth
elements, and {Yb4O}Cl6 [27] as an example for a divalent
rare-earth element. Recently, we have obtained two new
oxide-halides, Eu2OI2 with divalent europium [28] and
Eu2O2Br, a class I mixed-valence oxide-bromide with
clearly distinguished EuII and EuIII sites [29]. These were
obtained as by-products when the synthesis of BaEu4N2I8
and a large-scale preparation of {Eu4O}Br6 were at-
tempted. They contain tetrahedral {Eu4O} units, isolated in
{Eu4O}Br6 and connected via common edges to chains as
in Eu2OI2 and further to layers as in Eu2O2Br. However, in
all these compounds the valence of the rare-earth ion is
clearly two or three.
There are a growing number of oxide/nitride-halides of
rare-earth elements which prefer 4fnϪ15d1 electronic con-
figurations rather than 4fn5d0. These often have excess elec-
trons, thence attested by their metallic lustre. Gd3NCl6 [30],
Ce3NX6 (X ϭ Cl,Br) [31, 32], La3NBr6 [33], M14(C2)2(O/N)2I24
(M ϭ Ho,Y,Er) [34, 35], Na2Pr4O2Cl9 [36], Na2Pr4(NO)Br9
[37], Na2Gd4(NO)Cl9 [38], as well as Lu9C4OI8 [39] and
Y7C3OI6 [40], may serve as examples. In all of these, oxygen
or nitrogen atoms (as oxide and/or nitride) centre tetra-
hedra that share common edges to dimers, to chains or cor-
rugated layers. Of course, it is not easy, if not impossible,
to distinguish oxygen and nitrogen by a single-crystal X-
ray structure determination. Both tend to centre tetrahedra
while mono- and dicarbon tend to occupy octahedral or
trigonal-bipyramidal interstices, for which Sc{Sc6N}Cl12
[41], {Sc6C2}I11 [42], {Gd10(C2)2}Cl18 [43], and
Rb[{Pr5C2}Cl10] [44] are early examples. Carbon in tetra-
hedral interstices is rarely seen, although quite recently in
the supertetrahedral molecular solid Sc24C10I30 [45].
and cerium, AIILaI4 and AIICeI4 (AII ϭ Sr, Ba, Nd, Sm;
and EuLaI4), isostructural with BaLaI4 were obtained [12].
Of course, it was attempted to synthesize analogous bro-
mides and chlorides, with no success so far. However, in
one of these reactions we have obtained La4ZBr7 [10, 15].
In these reactions we have observed as by-products five
compounds with their colours as follows: La4ZBr7 (1):
black, Ce9Z4I16 (2): dark red, BaLa4Z2I8 (3): orange,
La9Z4I16 (4): black, and BaCe4Z2I8 (5): orange. To address
the nature of Z, refinements for mixed occupations of the
Z position with N and O with one temperature factor and
an overall 100 % occupation were carried out for all five
compounds.
These
gave
the
following
results:
La4(N0.91O0.09)Br7, Ce9(N3.01O0.99)I16, BaLa4(N1.07O0.93)I8,
La9(N3.71O0.29)I16, and BaCe4(N1.96O0.05)I8. Standard devi-
ations were generally about 1 in the first digit. Thus for
La4ZBr7, the composition is rather La4(N0.9(1)O0.1(1))Br7.
From structure refinement alone, one would address this
compound rather as La4NBr7, and not as previously
thought as La4OBr7 [10, 15]. The example of (4) makes it
further clear that these refinements have to be regarded
with great care, as the electron count with La3ϩ, N3Ϫ, O2Ϫ
and IϪ1 would be Ϫ0.71 electrons (!) for La9(N3.71O0.29)I16.
For (2) and (5), both cerium compounds, the electron count
would be zero for the compositions Ce9(N3O)I16 and Ba-
Ce4(N2)I8, in accord with the colours red and orange. For
(3) one would have one excess electron for BaLa4(NO)I8
although the compound is orange and for (1) there are al-
ways excess electrons regardless whether it is La4(N)Br7
(2eϪ), as the refinement seems to suggest, or La4(O)Br7
(3eϪ) as was once believed [46]. There could have also been
barium on the lanthanum and cerium positions. EDX
measurements gave, however, no hint for barium incorpor-
ated in the crystals.
The crystal structures of all five compounds, La4ZBr7 (1),
Ce9Z4I16 (2), BaLa4Z2I8 (3), La9Z4I16 (4) and BaCe4Z2I8
(5), are characterized by {M4Z} tetrahedra (M ϭ La,Ce),
Fig. 1, isolated in (1) and edge-connected to single chains
in the other four. These tetrahedra are defined by La-La
distances of, on the average, 388 pm for the isolated tetra-
hedron in (1) and 395 and 342 pm for the edge-connected
chains in (3) and (4) pm. The respective Ce-Ce distances in
(2) and (5) are 369 and 387 pm, see also Table 5. The La-Z
distances are in a narrow range, 240, 238 and 239 pm on
the average for (1), (3) and (4), and the respective Ce-Z
distances are 234 in (2), and 236 pm in (5), hence a bit
smaller subject to lanthanide contraction. These distances
compare quite well with the sum of Shannon’s crystal radii
[47] for coordination number 6 for M3ϩ and 4 for O2Ϫ, 241
and 239 pm, respectively, for La-Z and Ce-Z. In nitride-
tellurides M4N2Te3 [48] with edge-connected chains as
in (2) to (5) according to {M4/2N}Te1.5, slightly smaller
averaged La-N (237 pm) and Ce-N distances (234 pm) have
been observed recently.
When we have started to use alkaline-earth metals as re-
ducing agents for rare-earth halides [10Ϫ15], we have again
observed the formation of halides with metal tetrahedra
centered by an interstitial atom Z which might be oxygen
or nitrogen or even both in statistical distribution. As a by-
product of the action of barium on lanthanum triiodide
which yields essentially BaLaI4 [11] and LaI2, according to
Ba ϩ 2LaI3 ϭ BaLaI4 ϩ LaI2,
a few black single crystals of La9Z4I16 were obtained [10,
14]. They show only a weak metallic lustre which could im-
ply that oxygen could indeed be partly nitrogen. With a
composition of La9N3OI16, the compound would have no
excess electrons and no metallic lustre could be expected.
Subsequently, a number of ternary iodides with lanthanum
In the crystal structure of La4ZBr7 (1), the {La4Z} tetra-
hedron is surrounded by seven inner ligands (note the for-
mula!) according to {La4Z}(µ2-Br1)2(µ2-Br2)2(µ2-Br3)1(µ3-
2026
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Interstitially Stabilized Metal Tetrahedra
Table 5 Shortest, largest and averaged distances /pm for La4ZBr7
(1), Ce9Z4I16 (2) and BaLa4Z2I8 (3).
La4ZBr7
La-La
La-Z
La1-Br
La2-Br
La3-Br
372.5(1) Ϫ 397.0(1)
236.3(7) Ϫ 245.3(11)
298.4(1) Ϫ 362.2(1)
309.8(1) Ϫ 336.5(1)
300.0(1) Ϫ 373.1(1)
388.2
239.7
328.7
318.3
327.6
Ce9Z4I16
Ce-Ce
Ce-Z
Ce1-I
Ce2-I
Ce3-I
338.3(1) Ϫ 395.2(1)
228.0(5) Ϫ 236.3(6)
293.7(1) Ϫ 390.8(1)
329.2(1) Ϫ 355.8(1)
272.1(1) Ϫ 372.8(1)
368.6
233.9
337.8
343.6
319.1
BaLa4Z2I8
La-La
La-Z
Ba-I
La1-I
La2-I
350.9(1) Ϫ 408.3(18)
234.7(6) Ϫ 242.8(6)
342.3(10) Ϫ 375.3(24)
336.2(1) Ϫ 362.0(1)
327.6(19) Ϫ 376.0(8)
395.0
238.4
360.0
346.4
345.4
In the crystal structure of M9Z4I16, M ϭ Ce (2), La (4),
the {M4Z} tetrahedra are connected via common trans
edges to chains {M4/2Z}. Such chains, anti-analogous to
those known in SiS2, are rather common in the chemistry
of (reduced) rare-earth metal halides. The nitride-chlorides
{M4/2N}Cl3 (M ϭ La, Ce, Pr, Nd, Sm, Gd, Tb) [50, 51] as
well as Na2Pr4O2Cl9 [36], Na2Pr4(NO)Br9 [37] and
Na2Gd4(NO)Cl9 [38] all contain these chains. In M9O4I16,
the {M4/2O} chains run out of phase but still parallel to
each other, connected by iodide ions to layers perpendicular
to [010]. These {M4/2Z}I4 layers are stacked in the [010]
direction with two adjacent layers rotated by 90° against
each other (Fig. 3). Between these layers, the ninth metal
atom (M3), with respect to the formula M3[{M4/2Z}I4]4 ϭ
M3[M8Z4I16], occupies square anti-prismatic voids, see Fig.
3b, with very uniform La-I/Ce-I distances of 330.4(1)/
332.4(1) pm (4x each) and 326.3(1)/329.5(1) pm for
La9Z4I16 (4) and Ce9Z4I16 (2), respectively. The La-I dis-
tances are in good agreement with those found in LaI2
(335 pm) [10, 14], LaI (332 pm) [8, 9], an in BaLaI4
(335 pm) [11].
Fig. 1 {M4Z} units surrounded (a) by seven inner and twelve
outer bromide ligands in La4ZBr7 (1), (b) by six inner and ten outer
iodide ligands in both Ce9Z4I16 (2) and (c) BaLa4ZI8 (3).
Br4)2, Fig. 1a. La-Br distances lie in the range of 298
through 373 pm, see Table 5. The coordination sphere is
completed by i-i connections between the {La4Z}Br7 units
such that Br1 exhibits a coordination number of 3, Br2 and
Br3 of 4, and Br4 of 5 (Fig. 2a). A three-dimensional con-
nection is thereby created which is shown in projection onto
(001) in Fig. 2b. There are, of course, similarities between
the structure of {La4Z}Br7 and the structures of {M4O}X6
(with, in principle, M ϭ Ca, Sr, Ba, Sm, Eu, Yb and X ϭ
Cl, Br, I) with divalent cations [49]. Except for the ad-
ditional bromide anion in the former, the most important
difference is the arrangement of the {M4O} tetrahedra
which have four {M4O} nearest neighbours in {La4Z}Br7
and three nearest neighbours in {M4O}X6, see Figs. 2b
and 2c.
The crystal structures of M9Z4I16, M ϭ Ce (2), La (4),
and of BaM4Z2I8, M ϭ La (3) and Ce (5), are closely re-
lated to each other. This becomes obvious when the formu-
lae BaLa4Z2I8 x2 ϭ Ba2La8Z4I16 and CeCe8Z4I16 as well as
their cell volumina are compared, 2237.3(5) 106·pm3 and
8623.0(2) 106·pm3, differing by a factor of roughly four.
There is also some resemblance between the lattice con-
stants,
(2) CeCe8Z4I16, Fddd, Z ϭ 8, a ϭ 890.0(1), b ϭ 2264.1(2),
c ϭ 4279.5(4) pm
(3) Ba2La8Z4I16, C2/c, Z ϭ 4, a ϭ 897.5(1), c ϭ 1229.3(2),
b ϭ 2162.4(3) pm, β ϭ 110.32(1)°.
Z. Anorg. Allg. Chem. 2006, 2024Ϫ2030
 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
www.zaac.wiley-vch.de
2027

N. Gerlitzki, S. Hammerich, I. Pantenburg, G. Meyer
Fig. 3 Crystal structure of Ce9O4I16 (2). (a) Two {Ce4/2O} chains
and their connection via common bromide ligands to a layer paral-
lel (001). (b) The ninth cerium atom, Ce3, and its connection to
two {Ce4/2O} chains. (c) Projection of the crystal structure roughly
onto (010).
Roughly, the c and b axes have to be doubled when proceed-
ing from (3) to (2), hence the volume is quadrupled. The
major difference between both structures is, except for all
the crystallographic details such as for example different
space group symmetries, that in (3) an additional large
eight-coordinate atom, Ba2ϩ, is added. These [BaI8] poly-
hedra are no longer isolated from themselves as the [CeI8]
polyhedra in (2), Fig. 3b, but are edge-connected with like
[BaI8] polyhedra to chains {BaI8/4}, see Fig. 4. The BaI8/4
chains are rotated against the OLa4/2 chains, in projection
down [010], rotated against each other by about 35° (Fig.
4d). The Ba2ϩ-IϪ distances are with 360 pm considerably
longer than the La3ϩ-IϪ distance with an overall average of
about 346 pm (∆ ϭ 14 pm), owing to the different ionic
radii of Ba2ϩ and La3ϩ, ∆ ϭ 26 pm [47].
Acknowledgements. This work was generously supported by the
Deutsche Forschungsgemeinschaft, Bonn (Sonderforschungs-
bereich 608 Köln “Komplexe Übergangsmetallverbindungen mit
Spin- und Ladungsfreiheitsgraden und Unordnung” and Schwer-
punktprogramm 1166 “Lanthanoidspezifische Funktionalitäten“)
and by the State of Nordrhein-Westfalen and the Universität zu
Köln.
Fig. 2 Features of the crystal structure of La4ZBr7 (1). (a) Sur-
rounding of the four crystallographically independent bromine
atoms. (b) Projection on (001). (c) For comparison: Projection of
the crystal structure of Sm4OI6 onto (001).
2028
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Z. Anorg. Allg. Chem. 2006, 2024Ϫ2030

Interstitially Stabilized Metal Tetrahedra
[8] M. Ryazanov, L. Kienle, A. Simon, Hj. Mattausch, Inorg.
Chem. 2006, 45, 2068.
[9] J. D. Martin, J. D. Corbett, Angew. Chem. 1995, 107, 234; An-
gew. Chem. Int. Ed. Engl.1995, 34, 233.
[10] N. Gerlitzki, Dissertation, Universität zu Köln, 2002.
[11] N. Gerlitzki, G. Meyer, Z. Anorg. Allg. Chem. 2002, 628, 915.
[12] N. Gerlitzki, St. Hammerich, G. Meyer, Z. Anorg. Allg. Chem.
2004, 630, 2431.
[13] N. Gerlitzki, A.-V. Mudring, G. Meyer, Z. Anorg. Allg. Chem.
2005, 631, 381.
[14] G. Meyer, N. Gerlitzki, S. Hammerich, J. Alloys Compd. 2004,
380, 71.
[15] N. Gerlitzki, G. Meyer, Z. Anorg. Allg. Chem. 2002, 628, 2199;
S. Hammerich, Diplomarbeit, Universität zu Köln, 2002.
[16] G. Meyer, S. Dötsch, Th. Staffel, J. Less-Common Met. 1987,
127, 155.
[17] G. Meyer, in: Synthesis of Lanthanide and Actinide Compounds
(G. Meyer, L. R. Morss, eds.), Kluwer Academic Publishers,
Dordrecht, 1991, p. 135.
[18] G. M. Sheldrick, SHELXL-97, Program for the Refinement of
Crystal Structures, Göttingen, 1997.
[19] P. J. C. Wilson (ed.), International Tables for X-Ray Crystal-
lography, Oxford Science Publications, Oxford, 1992.
[20] X-SHAPE 1.01, Crystal Optimization for Absorption Correc-
tion, STOE & Cie GmbH, Darmstadt, 1996; X-RED 1.22,
Stoe Data Reduction Program (C), Stoe & Cie GmbH, Darm-
stadt, 2001.
[21] A. Altomare, G. Cascarano, A. Guagliardi, C. Giacovazzo, J.
Appl. Crystallogr. 1994, 27, 435.
[22] La9Z4I16: La9N3.71O0.29 16
(3337.21 g molϪ1); diffractometer
I
IPDS-I, Stoe, Darmstadt; Mo-Kα (graphite monochromator,
λ ϭ 71.073 pm); T ϭ 293(2) K; θmax ϭ 24.15°; 100 images, 0°
Յ ϕ Յ 200°; ∆ϕ ϭ 2°; indices: Ϫ25 Յ h Յ 25, Ϫ49 Յ k Յ 49,
Ϫ10 Յ l Յ 10; ρcalc ϭ 4.992 g cmϪ3; 13401 reflection intensit-
ies measured of which 1766 were symmetrically independent,
Rint ϭ 0.0631, F(000) ϭ 11114, µ ϭ 19.582 mmϪ1. Ortho-
rhombic, Fddd (no. 70), a ϭ 2289.3(3), b ϭ 4315.6(6), c ϭ
898.8(1), V ϭ 8880(2) 106·pm3, Z ϭ 8, R values: R1/wR2 for
1498 reflections with I0>2σ(I0): 0.0254/0.0631 and for all data:
0.0333/0.0652; Sall ϭ 1.075.
[23] BaCe4Z2I8: BaCe4N1.96O0.05 8
fractometer IPDS-I, Stoe, Darmstadt; Mo-Kα (graphite
monochromator, λ ϭ 71.073 pm); T ϭ 293(2) K; θmax
28.13°; 100 images, 0° Յ ϕ Յ 200°; ∆ϕ ϭ 2°; indices: Ϫ11 Յ
h Յ 11, Ϫ28 Յ k Յ 28, Ϫ15 Յ l Յ 14; ρcalc ϭ 5.301 g cmϪ3
I
(1741.13 g·molϪ1); dif-
ϭ
;
Fig. 4 Crystal structure of BaLa4Z2I8 (3). Views (a) onto and
along one {La4/2Z} chain and (b) onto and along one BaI8/4 chain.
(c) Projection of the crystal structure onto (100). (d) Projection of
the crystal structure onto (010).
13077 reflection intensities measured of which 2553 were sym-
metrically independent, Rint ϭ 0.0673, F(000) ϭ 2904, µ ϭ
21.257 mmϪ1. Monoclinic, C2/c (no. 15), a ϭ 890.2(1), b ϭ
2149.7(3), c ϭ 1215.1(1) pm, β ϭ 110.25(1)°, V ϭ 2181.5(5)
106·pm3, Z ϭ 4. R values: R1/wR2 for 1866 reflections with
I0>2σ(I0): 0.0329/0.0527 and for all data: 0.0551/0.0564;
Sall ϭ 0.893.
References and Notes
[1] F. Wöhler, Poggendorffs Ann. 1828, 13, 577.
[24] Further details of the crystal structure determinations may be
obtained from the Fachinformationszentrum Karlsruhe,
[2] E. Zintl, S. Neumayr, Z. Elektrochem. 1933, 39, 84.
[3] W. Klemm, H. Bommer, Z. Anorg. Allg. Chem. 1937, 231, 138.
[4] G. Meyer, Th. Schleid, Inorg. Chem. 1987, 26, 217.
[5] G. Meyer, Chem. Rev. 1988, 88, 93.
[6] G. Meyer, Th. Schleid, in: Synthesis of Lanthanide and Actinide
Compounds (G. Meyer, L. R. Morss, eds.), Kluwer Acad.
Publ., Dordrecht, NL, 1991, 175.
[7] G. Meyer, M. S. Wickleder, Handbook on the Physics and
Chemistry of Rare Earths (K. A. Gschneidner, L. Eyring, eds.),
Elsevier Science, 2000, 28, 53.
D-76344
Eggenstein-Leopoldshafen,
Germany
(fax:
(ϩ49)7247-808-666; e-mail: crysdata@fizkarlsruhe.de), on
quoting the depository numbers ICSD-416395 for La4ZBr7
(1), ICSD-416396 for Ce9Z4I16 (2), ICSD-416397 for
BaLa4Z2I8 (3), ICSD-416398 for La9Z4I16 (4) and ICSD-
416399 for BaCe4Z2I8 (5), the authors and the journal citation.
[25] Th. Schleid, G. Meyer, J. Less Common Met. 1989, 149, 73.
[26] G. Meyer, Th. Schleid, Z. Anorg. Allg. Chem. 1986, 533, 181.
[27] Th. Schleid, G. Meyer, J. Less-Common Met. 1987, 127, 161.
Z. Anorg. Allg. Chem. 2006, 2024Ϫ2030
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N. Gerlitzki, S. Hammerich, I. Pantenburg, G. Meyer
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{Ca4O}Cl6: H.-J. Meyer, G. Meyer, M. Simon, Z. Anorg. Allg.
Chem. 1991, 596, 89; {Sr4O}Cl6: H. Hagemann, F. Kubel, H.
Bill, Eur. J. Inorg. Chem. 1996, 1101; O. Reckeweg, H.-J.
Meyer, Z. Kristallogr. 1997, 212, 235; {Sr4O}I6: M. G. Barker,
M. G. Francesconi, T. H. Shutt, C. Wilson, Acta Crystallogr.
2001, E57, 44; {Ba4O}Cl6: B. Frit, B. Holmberg, J. Galy, Acta
Crystallogr. 1970, B26, 16; H.-J. Meyer, O. Reckeweg, private
communication 2004, ICSD 408175; {Ba4O}I6: M. G. Barker,
M. G. Francesconi, C. Wilson, Acta Crystallogr. 2001, E57,
41; {Sm4O}Cl6: Th. Schleid, G. Meyer, Z. Anorg. Allg. Chem.
1987, 553, 231; {Sm4O}I6: S. Hammerich, I. Pantenburg,
G. Meyer, Acta Crystallogr. 2005, E61, i234Ϫi236; {Eu4O}Cl6
and {Eu4O}Br6: Th. Schleid, G. Meyer, Z. Anorg. Allg. Chem.
1987, 554, 118; {Eu4O}I6: W. Liao, R. Dronskowski, Acta
Crystallogr. 2004, C60, i23; {Yb4O}Cl6: Th. Schleid, G. Meyer,
J. Less-Common Met. 1987, 127, 161.
2006, 632, 1487.
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[34] Hj. Mattausch, H. Borrmann, R. Eger, R. K. Kremer, A.
Simon, Z. Naturforsch. 1995, 50b, 931.
[35] G. Meyer, F. Steffen, Z. Kristallogr. 1995, Suppl. 9, 201; F.
Steffen, G. Meyer, Z. Naturforsch. 1995, 50b, 1570.
[36] H. Mattfeld, G. Meyer, Z. Anorg. Allg. Chem. 1994, 620, 85.
[37] M. Lulei, J. D. Corbett, Inorg. Chem. 1995, 34, 2671.
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[39] H. Mattfeld, K. Krämer, G. Meyer, Z. Anorg. Allg. Chem.
1993, 619, 1384.
[40] Hj. Mattausch, H. Borrmann, A. Simon, Z. Naturforsch. 1993,
48b, 1828.
[41] S.-J. Hwu, J. D. Corbett, J. Solid State Chem. 1986, 64, 331.
[42] D. Dudis, J. D. Corbett, Inorg. Chem. 1987, 26, 1933.
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