Synthesis and crystal structure of new ternary chalcogenides of group IV metals: K2ZrS4, Rb2ZrS4, and Rb2HfS4

Article abstract of DOI:10.1515/znb-2000-0805

The new ternary one-dimensional chain compounds K₂ZrS₄, Rb₂ZrS₄ and Rb₂HfS₄ were prepared at 350 °C by reacting A₂S₃ and S with elemental M (A = K, Rb; M = Zr, Hf). They are isostructural, crystallizing in the orthorhombic space group Pbca with Z = 8. The M atoms are in a distorted octahedral environment of four S^2- anions and one S₂^2- unit. The structure consists of infinite anionic chains comprised of edge-sharing MS₆ octahedra running parallel to the [001] direction separated by the alkali metal cations. The composition of the chain may be formulated as ¹_∞[MS_4/2(S₂)^2-]. The two crystallographically independent alkali cations are in eight-and ninefold coordination of S atoms.

Full text of DOI:10.1515/znb-2000-0805

Synthesis and Crystal Structure of New Ternary Chalcogenides
of Group IV Metals: K2ZrS4, Rb2ZrS4, and Rb2HfS4
C. Rumpf and W. Bensch
Institut für Anorganische Chemie der Christian-Albrechts-Universität Kiel,
Olshausenstraße 40, D-24098 Kiel, Germany
Reprint requests to Prof. Dr. W. Bensch. Fax: +49 (0)431-8801520.
E-mail: wbensch@ac.uni-kiel.de
Z. Naturforsch. 55 b, 695-698 (2000); received Mai 2, 2000
Polychalcogenides, Zirconium, Hafnium
The new ternary one-dimensional chain compounds K
prepared at 350 °C by reacting A and S with elemental M (A = K, Rb; M = Zr, Hf). They
are isostructural, crystallizing in the orthorhombic space group Pbca with Z = . The M atoms
are in a distorted octahedral environment of four S2_ anions and one S 2~ unit. The structure
consists of infinite anionic chains comprised of edge-sharing MS octahedra running parallel
to the [001] direction separated by the alkali metal cations. The composition of the chain may
be formulated as j-,[MS
(S )2-]. The two crystallographically independent alkali cations are
in eight- and ninefold coordination of S atoms.
2
ZrS
4
, Rb
2
ZrS
4
and Rb
2
HfS were
4
2
S
3
8
2
6
4
/
2
2
Introduction
Table 1. Atomic coordinates (TO4) and equivalent dis-
placement parameters Ueq (A 103).
2
Ternary group 4 transition metal alkali chalco­
genides have received much attention with respect
to their low dimensional crystal structures. The
metal atoms show a high flexibility of the coor­
dination environment in the MIVQr polyhedra with
X
z
ueq
y
K2ZrS4:
Zr
3294(1)
1652(1)
2707(1)
5922(1)
5515(1)
692(1)
5531(1)
3666(1)
2883(1)
5705(1)
3860(1)
625(1)
6316(1)
5660(1)
7055(1)
6610(1)
5884(1)
8022(1)
4683(1)
5(1)
x ranging from 4 to
nected in different ways. Examples containing ID
anionic chains are Tl TiS ], Rb Zr Tei ], and
Ti Si [3]. In Tl TiS distorted TiS octahedra
are connected via common edges to form zig­zag
chains (angle Ti­Ti­Ti 132.5°). In Rb Zr Tej each
8
. These polyhedra are intercon­ S(l)
9
(1)
S(2)
S(3)
S(4)
K (l)
K(2)
9(1)
1 2
1 2
(
(
1
1
)
)
2
4
[
1
4
3
6
[2
K4
3
4
2
4
6
16(1)
16(1)
1430(1)
7014(1)
4
3
6
RbiZrS\:
Zr atom is surrounded by eight Te atoms forming
distorted bicapped trigonal prisms. The polyhedra
share opposite triangular faces. Finally, in K 4 T 13S 14
Zr
S(l)
S(2)
3271(1)
1694(1)
2670(1)
5840(1)
5417(1)
5377(1)
3504(1)
2762(1)
5517(1)
3729(1)
465(1)
6311(1)
5676(1)
7028(1)
6590(1)
5881(1)
8012(1)
4656(1)
8
(
(
(
1
)
)
)
1 1
1 2
1
1
TiS
7
and TiSg polyhedra are connected by shar­ S(3)
14(1)
15(1)
16(1)
18(1)
S(4)
Rb(l)
Rb(2)
ing common edges or trigonal faces to build linear
chains.
6 8 8
(1 )
1431(1)
6910(1)
Rb2H ß 4:
Experimental
Hf
3265(1)
1685(1)
2724(1)
5818(1)
5334(1)
3476(2)
2669(2)
5499(2)
3718(2)
433(1)
6312(1)
5683(1)
7022(1)
6592(1)
5874(1)
8015(1)
4656(1)
7(1)
9(1)
A
2
MS
with elemental M (M = Zr, Hf) and S in a 3:2:6 molar
ratio. A was made from the stoichiometric reaction of
4
was prepared by reacting A
2
S
3
(A = K, Rb)
S(l)
S(2)
S(3)
S(4)
Rb(l)
Rb(2)
1 0
(
(
1
)
)
2
S
3
1 2
1
5
404(1)
13(1)
14(1)
16(1)
elemental A with S in liquid ammonia. The starting mate-
rials were thoroughly mixed in a dry-box and loaded into a
glass tube which was evacuated to 1 0 “ 5 mbar and sealed.
720(1)
1433(1)
6897(1)
0
932­0776/00/0800­0695 $ 06.00 © 2000 Verlag der Zeitschrift für Naturforschung, Tübingen • www.znaturforsch.com
K
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96
C. Rumpf and W. Bensch • New Ternary Chalcogenides of Group IV Metals
MS
Table 2. Technical details of data acquisition and some refinement results for A
2
4
.
K2ZrS4
Rb2ZrS4
Rb2HfS4
«
[A]
9.4541(6)
6.7021(4)
9.7488(4)
6.7234(3)
23.675(2)
1551.8(2)
3.342
9.7430(6)
6.6754(3)
23.602(2)
1535.1(3)
4.134
H A ]
2
2.966(2)
455.2(2)
2.717
80
1
Calc, density [g/cm3]
1
180
14.85
180
27.17
T[K]
ß [mm
]
3.68
F(000)
1136.0
1424.0
1680.0
Index range
-13 < /? < 13, 8 < &< 8, -13 < h < 13, 8 < k < 8, -13 < h < 13,9 < k < 9,
-
32 < / < 32
-33 < / < 33
-33 < I < 33
Reflections collected
Independent refl.
14494
2062
16247
2121
18124
2280
Refl. with F > 4 cr(F)
1949
1978
2139
Rm [%]
4.80
0.4612/0.6774
65
4.05
0.1357/0.1906
65
0.0021(4)
0.0349, 0.74
2.12
4.80
0.0471/0.0914
65
0.0009(2)
0.0351,6.16
2.53
Min./max. transm.
NJ a u] mber of parameters
0
.0020(5)
J, «W
0.0320, 0.35
1.96
5.11
R 1 for all F0 > 4 cr(F0) [%]
wR2 for all reflections [%]
GOOF
5.28
1.071
6.68
1.205
1.114
<SF [eA~3]
0.57/-1.06
0.69/-1.24
5.57/-2.00
[al F* = Fc (k[l + 0.001 •x • Fc2 • A3 / sin (20)]"0-25) ; Ib] w = 1/[<t2(F02) + (y-P)2 + z-P]; P = (Max (Fo2,0) + 2-Fc 2)/3.
Table 3. Selected bond distances [A] and angles [°] for
the compounds A MS4.
2
K2ZrS4
Rb2ZrS4
Rb2HfS4
Bond distances [Ä]:
M -S(l)
M-S(2)
M-S(2)
M-S(4)
M -S(l)
M-S(3)
S(3)-S(4)
2.4993(4) 2.4930(6) 2.472(1)
2.5013(4) 2.5092(6) 2.484(1)
2.5163(4) 2.5132(6) 2.500(1)
2.5782(4) 2.5766(6) 2.564(1)
2.5872(4) 2.5859(6) 2.570(1)
2.5775(4) 2.5918(6) 2.576(1)
2.1105(5) 2.1061(8) 2.110(2)
Shortest interchain 3.635
S-S distance
3.884
3.850
Angles [°]:
Fig. 1. The coordination of the M atom in A
with the numbering scheme.
2
MS4together
S(3)-M-S(4)
M-M-M
48.33(2)
131.75
48.09(2)
131.8
48.48(4)
131.85
All single crystal X-ray investigations were performed
The ampoules were placed in a computer controlled fur- on a STOE imaging plate diffraction system (IPDS) with
nace and heated from r.t. to 350 °C within 5 h. They were
held at this temperature for 6 d and then slowly cooled
an area detector, monochromated Mo-KQ radiation (A =
0.71073 A), and a low temperature device from Oxford
down to r.t. with a cooling rate of 3 °C/h. To remove un- Cryosystems. Technical details of the data acquisition
reacted alkali metal polychalcogenides the resultant melt
was washed with DMF and ether.
as well as some refinement results are summarized in
Table 2. Atomic coordinates are listed in Table 1 and
selected interatomic separations are given in Table 3.
Structure solution was performed using SHELXS-97.
Refinement was done against F2 using SHELXL-97. A
The compounds consist of yellow coloured crystals
(
yield: ~20% based on M) which are highly unstable in
humid air.
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C. Rumpf and W. Bensch • New Ternary Chalcogenides of Group IV Metals
697
|
*S
•
A
Fig. 2. Crystal structure of A
2
MS viewed along [010].
4
face indexed absorption correction was applied. All atoms
were refined using anisotropic displacement parameters.
All compounds are isostructural and were refined in the
orthorhombic space group Pbca.
Further details on the structure determination can be
obtained from the Fachinformationszentrum Karlsruhe,
D-76344 Eggenstein-Leopoldshafen (Fax: +49 (0)7247-
The S­S bond length in the S unit (S3 ­ S4) is
about 2.11 A which is typical for single bonds (see
Table 3).
2
Because the S22­ unit is bound to MIV in an ij2
mode the resulting angle S3­M­S4 is fixed and it
ranges from 48.09(2)° to 48.48(4)°. As a conse­
quence the other angles in the octahedra deviate
from the ideal geometry giving rise to a strong dis­
tortion (see Fig. 1).
8
08-666; e-mail: crysdata@fiz-karlsruhe.de) under No.
CSD-411329 (K2ZrS4), CSD-411330 (Rb2HfS4), and
CSD-411331 (Rb2ZrS4).
The octahedra are connected by two /i-S atoms
leading to the formation of one­dimensional infinite
Results and Discussion
c
4
[MS
4
/ (S2)2_] anionic chains running parallel to
2
The ternary compounds crystallize in the or­
the [0 1 0 ] direction.
thorhombic space group Pbca with Z =
8
. The tran­
sition metal ions in A MS are in an octahedral
2
4
A view of the unit cell of A
2
MS (A = K and
4
environment of four /i­S2~ anions and one rj1-S22~ Rb, M = Zr and Hf) is shown in Figure 2. The zig­
unit. The average M­S distances range from 2.54 A zag chains (M­M­M = 131.8°) are separated by two
(Zr­S) to 2.53 Ä (Hf­S) and correspond well with the crystallographically unique alkali metal cations: A
1
sum of the ionic radii of ZrIV, HfIV and S2_. They is coordinated by nine, A2 by seven S atoms (cut­
are comparable to those in other Zr and Hf sulfides off A­S = 3.9 A) within irregular polyhedra. The
like Na
2
ZrS
3
[4], Ba
3
Zr2
S
7
[5] and Cu
2
HfS
3
[6
],
A­S distances correspond to the sum of their ionic
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98
C. Rumpf and W. Bensch • New Ternary Chalcogenides of Group IV Metals
The lattice parameters of Rb
2
ZrS are very simi­
4
lar to those of Rb HfS due to the very similar radii
2
4
of ZrIV (0.72 Ä) and Hflv (0.71 Ä) [9].
The structures of the title compounds are isostruc­
tural to Tl
2
TiS
4
[
1
] and can be derived from Cs
2
TiS
3
[
10] in a simple way. In Cs
2
TiS the Ti atom is co­
3
ordinated by five S atoms within a square pyramid.
The TiSs units are connected by common edges to
form JD[TiS
and A MS
4
/
2
(S)2“ ] chains. The chains of Cs
2
TiS
3
2
4
are compared in Fig. 3, where the struc­
tural differences are obvious.
The structures of the title compounds result when
a single S2~ anion in A
rf-S 2~­unit to give A MS4. Further substitution
of chalcogen atoms (Q2 ­) by Q 2~­units leads to
higher coordinated M atoms as in Cs
(b). Cs Ti Ten, Cs Hf Te26 [12] and A
2
MS
3
is replaced by the
2
2
2
4
Zr3
Tei [11],
6
Fig. 3. Comparison of the ^ [ M S ^ ^ ) 2 1 chain in
A
2
MS
4
(a) with the J-,[TiS
4
/
2
(S)2~] chain in Cs
2
TiS
3
3
3
5
5
4
M
3
Q
J4 (A = K,
Rb, Cs; M = Ti, Zr, Hf; Q = S, Se) [13].
Our attemps to prepare the Cs compound CS
Zr Si [13] which is
chains is about 3.64 A for the potassium compound isostructural with IQ ^ S u . In this compound the
and is larger as expected for Rb ZrS (3.88 A) and Ti atoms are seven­ and eightfold coordinated. Ob­
Rb HfS (3.85 A) indicating no S­S interaction. viously, the coordination number of M depends on
Therefore, the formal oxidating states may be as­ the charge/radii ratio and the stoichiometry of the
radii and agree with those found in K
2
TiS
3
[7] or
2
ZrS
4
Rt>
2
S
2
[
8
]. The shortest S­S distance between the led to the formation of Cs
4
3
4
2
4
2
4
signed as A1, MIV, S2~ and S
2
2 ­.
compound.
Obviously the increase of the b axis with increas­
ing size of the alkali cation (Rb+ > K+) is very small
due to the rigidity of the metal centered octahedra.
Acknowledgements
We gratefully acknowledge the financial support by
However, the a as well as the c axis are strongly the state of Schleswig-Holstein and the Deutsche For-
influenced by the alkali cation size.
schungsgemeinschaft (DFG).
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