Hexachloroplatinates of the lanthanides: Syntheses and thermal decomposition of [M(NO3)2(H2O) 6]2[PtCl6] · 2H2O (M = La, Pr) and [M(NO3)(H2O)7][PtCl6] · 4H2O (M = Gd, Dy)

Article abstract of DOI:10.1002/zaac.200700405

The reaction of the nitrates M(NO₃)₃ · 6H ₂O (M = La, Pr) and (H₃O)₂PtCl₆ led to yellow single crystals of [M(NO₃)₂(H₂O) ₆]₂[PtCl₆] · 2H₂O (M = La, Pr) (monoclinic, P2₁/c, Z = 2, La/Pr: a = 697.4(3)/695.5(1), b = 1654.5(1)/1652.5(2), c = 1317.7(6)/1318.5(3) pm, β = 93.97°(7)/93. 93°(2), R_all = 0.0169/0.0659) while the reaction of M(NO ₃)₃ · 5H₂O (M = Gd, Dy) and (H ₃O)₂PtCl₆ yielded yellow single crystals of [M(NO₃)(H₂O)7][PtCl₆] · 4H₂O (monoclinic, P21/n, Z = 4, Gd/Dy: a = 838.72(3)/838.40(2), b = 2131.98(6)/2139.50(7), c = 1142.63(3)/1143.10(3) pm, β = 95.670(4)/95.698(3), R_all = 0.0475/0.0337). The crystal structures consist of octahedral [PtCl₆]^2- anions and complex [M(NO₃)₂(H₂O)₆]₂ ⁺ and [M(NO₃)(H₂O)₇]²⁺ cations, respectively. The thermal decomposition of both types of compounds leads via various steps to elemental platinum and the oxide chlorides MOCl (M = La, Pr, Gd, Dy).

Full text of DOI:10.1002/zaac.200700405

DOI: 10.1002/zaac.200700405
Hexachloroplatinates of the Lanthanides: Syntheses and Thermal
Decomposition of [M(NO3)2(H2O)6]2[PtCl6]·2H2O (M ؍ La, Pr) and
[M(NO3)(H2O)7][PtCl6]·4H2O (M ؍ Gd, Dy)
Annika Arndt, Damir Posavec, Stefan Schwarzer, and Mathias S. Wickleder*
Oldenburg, Carl von Ossietzky Universität, Intitut für Reine und Angewandte Chemie
Received June 4th, 2007; accepted August 6th, 2007.
Abstract. The reaction of the nitrates M(NO3)3 ·6H2O (M ϭ
La, Pr) and (H3O)2PtCl6 led to yellow single crystals of
1143.10(3) pm, β ϭ 95.670(4)/95.698(3), Rall ϭ 0.0475/0.0337). The
crystal structures consist of octahedral [PtCl6]2Ϫ anions and com-
plex [M(NO3)2(H2O)6]2 and [M(NO3)(H2O)7]2ϩ cations, respec-
ϩ
[M(NO3)2(H2O)6]2[PtCl6]·2H2O (M
P21/c, Z ϭ 2, La/Pr: a ϭ 697.4(3)/695.5(1), b ϭ 1654.5(1)/1652.5(2),
1317.7(6)/1318.5(3) pm, 93.97°(7)/93.93°(2), Rall ϭ
ϭ
La, Pr) (monoclinic,
tively. The thermal decomposition of both types of compounds
leads via various steps to elemental platinum and the oxide chlo-
rides MOCl (M ϭ La, Pr, Gd, Dy).
c
ϭ
β
ϭ
0.0169/0.0659) while the reaction of M(NO3)3 ·5H2O (M ϭ Gd,
Dy) and (H3O)2PtCl6 yielded yellow single crystals of
[M(NO3)(H2O)7][PtCl6]·4H2O (monoclinic, P21/n, Z ϭ 4, Gd/Dy:
a ϭ 838.72(3)/838.40(2), b ϭ 2131.98(6)/2139.50(7), c ϭ 1142.63(3)/
Keywords: Solid state structures; Platinum; Chlorides; Thermal
behaviour
Introduction
Results and Discussion
Crystal Structures
One of the most important platinum compounds is the so-
called hexachloroplatinic acid that can be obtained from
the metal and aqua regia. The acid is said to crystallize with
variable amounts of crystal water but only the dihydrate
has been investigated properly, and should be formulated
according to (H3O)2[PtCl6] [1]. The acid is the basis for a
large number of further platinum compounds, e.g.
(NH4)2[PtCl6] that is used for the preparation of the finely
devided metal, called platinum black. Hexachloroplatinic
acid is also the initial compound for the synthesis of tetra-
chloroplatinates, and reduction is usually achieved with
N2H4 [2]. Despite of their importance, hexachloroplatinates
and tetrachloroplatinates are only known for a very limited
number of metals. In particular, for the rare earth elements
no investigations have been undertaken up to now. As our
group focuses on both, rare earth and precious metal chem-
istry we decided to investigate in a more systematic way
chloroplatinates of rare earth elements and their behaviour,
with special emphasis on the thermal properties of the com-
pounds. Here we present the first hexachloroplatinates of
the lanthanides.
The crystal structure of [M(NO3)2(H2O)6]2[PtCl6]·2H2O
(M ϭ La, Pr) consists of [PtCl6]2Ϫ anions, complex
[M(NO3)2(H2O)6]ϩ cations and crystal water molecules.
The platinum atoms of the nearly perfect octahedral
[PtCl6]2Ϫ anions are located at the special site 2a of space
group P21/c (Table 2) and the ClϪ ions are found within a
narrow distance range between 232 and 234 pm (Table 3).
The
anions
are
separated
by
the
complex
[M(NO3)2(H2O)6]ϩ cations that show the M3ϩ centres in
tenfold coordination of oxygen atoms at distances from 242
to 273 pm (Table 3). Six of the oxygen atoms belong to the
H2O molecules, the remaining four are provided by two
Ϫ
chelating NO3 ions. The coordination polyhedron is a tri-
gonal prism that is capped over its three rectangular faces
as well as over one edge (Fig. 1). The oxygen atom that is
located above the edge belongs to one of the nitrate groups.
The latter are in trans position with respect to each other
and the distances N-O within the nitrate groups are longer
to those oxygen atoms that are bonded to M3ϩ ions
(around 127 pm) compared to those to the non-coordinated
oxygen atoms (123 pm). The same situation has been ob-
served for the anionic complex [Pr(H2O)4Cl2(NO3)2]Ϫ in the
crystal structure of PrCl2(NO3)·5H2O [3]. The complex
[M(NO3)2(H2O)6]ϩ cations and the [PtCl6]2Ϫ octahedra are
arranged in the unit cell as shown in Figure 2. The crystals
structure is completed by two H2O molecules of the same
crystallographic species (O7). The molecules are held in the
structure by hydrogen bonds with the shortest donor-
acceptor distance being 259 pm.
* Prof. Dr. M. S. Wickleder
Institut für Reine und Angewandte Chemie
Carl von Ossietzky Universität Oldenburg
D-26111 Oldenburg
Fax: 0441 798 3352
E-Mail: mathias.wickleder@uni-oldenburg.de
Z. Anorg. Allg. Chem. 2008, 634, 431Ϫ435
© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
431

A. Arndt, D. Posavec, S. Schwarzer, M. S. Wickleder
Table
1
Crystal data and structure refinement of
Table 2 Atom positions and equivalent thermal displacement
parameters for [M(NO3)2(H2O)6]2[PtCl6]·2H2O (M ϭ La, Pr)
[M(NO3)2(H2O)6]2[PtCl6]·2H2O (M ϭ La, Pr)
2
a)
˚
Ueq. / A
atom
Wyckoff
x/a
y/b
z/c
[La(NO3)2(H2O)6]2[PtCl6]· [Pr(NO3)2(H2O)6]2[PtCl6]·
2H2O
2H2O
La1
Pr1
O1
4e
4e
4e
4e
4e
4e
4e
4e
4e
4e
4e
4e
4e
4e
2a
2a
4e
4e
4e
4e
4e
4e
4e
4e
4e
4e
4e
4e
4e
4e
4e
4e
4e
4e
4e
4e
4e
4e
4e
4e
0.50320(2)
0.5007(1)
0.2876(3)
0.291(2)
0.7662(3)
0.759(2)
0.2594(3)
0.256(2)
0.4187(3)
0.416(2)
0.6933(3)
0.694(2)
0.5635(3)
0.571(2)
0
0.809672(7)
0.81196(5)
0.7021(1)
0.7026(7)
0.9094(1)
0.9104(7)
0.7058(1)
0.7110(7)
0.8574(1)
0.8611(8)
0.8523(1)
0.8534(8)
0.6744(1)
0.64932(1)
0.64812(6)
0.9876(2)
0.9859(9)
0.7147(2)
0.7151(9)
0.6869(2)
0.689(1)
0.8263(2)
0.8245(9)
0.5017(2)
0.5041(9)
0.5477(1)
0.00809(5)
0.0225(2)
0.0206(4)
0.045(3)
0.0161(4)
0.040(3)
0.0159(4)
0.041(3)
0.0185(4)
0.046(3)
0.0206(5)
0.047(3)
0.0177(4)
0.050(3)
0.00841(5)
0,0182(2)
0.0157(1)
0.0360(9)
0.0155(1)
0.040(1)
0.0174(1)
0.040(1)
0.0136(5)
0.031(3)
0.0171(4)
0.041(3)
0.0177(4)
0.040(3)
0.0216(4)
0.055(4)
0.0128(5)
0.027(3)
0.0145(4)
0.033(2)
0.0183(4)
0.042(3)
0.0194(4)
0.046(3)
0.0222(5)
0.052(3)
lattice parameter
a ϭ 697.4(3) pm
b ϭ 1654.5(1) pm
c ϭ 1317.7(6) pm
β ϭ 93.97°(7)
1516.9(1) A
2.596
a ϭ 695.5(1) pm
b ϭ 1652.5(2) pm
c ϭ 1318.5(3) pm
β ϭ 93.93°(2)
1511.8(5) A
2.552
O2
3
3
˚
˚
cell volume
O3
density (calcd.) /(g/cm3)
number of formula units
crystal system
space group
O4
2
monoclinic
P21/c (no. 14)
Stoe IPDS I
O5
diffractometer
radiation
temperature
O6
Mo-Kα (graphite monochrom, λϭ71.07 pm)
153.0 K
0.6785(7)
0.556(1)
1
1
296.0 K
3.3° < 2θ < 52.1°
Pt1
Cl11
Cl12
Cl13
N1
/
/
/
/
2
2
1
1
0
θ range
2
2
0.9916(1)
0.9901(6)
0.3047(1)
0.3059(6)
0.1389(1)
0.1363(7)
0.2152(3)
0.215(2)
0.1540(3)
0.152(2)
0.3941(3)
0.392(2)
0.1069(3)
0.111(2)
0.8247(3)
0.816(2)
0.8593(3)
0.856(2)
0.6515(3)
0.642(2)
0.9509(3)
0.939(2)
0.3024(4)
0.299(2)
0.63707(3)
0.6361(2)
0.51359(3)
0.5160(3)
0.47039(4)
0.4684(3)
0.5450(1)
0.5463(7)
0.6104(1)
0.6108(7)
0.5415(1)
0.5428(7)
0.4880(1)
0.4880(8)
0.7155(1)
0.7180(7)
0.7424(1)
0.7478(7)
0.7215(1)
0.7240(7)
0.6851(1)
0.6869(8)
0.5854(1)
0.5865(7)
0.45573(5)
0.4526(3)
0.58172(5)
0.5794(3)
0.34850(4)
0.3485(3)
0.1210(2)
0.1173(9)
0.1590(1)
0.155(1)
0.1070(1)
0.1050(9)
0.0981(2)
0.099(1)
0.7750(2)
0.7764(9)
0.6875(1)
0.6894(8)
0.8009(1)
0.7984(9)
0.8325(1)
0.8346(9)
0.8441(2)
0.843(1)
rotation range, ϕ increment 0° < ϕ < 300.3°, 1.3°
0° < ϕ < 300.3°, 1.3°
Ϫ8 Յ h Յ 8
Ϫ20 Յ k Յ 20
Ϫ16 Յ l Յ 16
231
index range
Ϫ7 Յ h Յ 7
Ϫ20 Յ k Յ 20
Ϫ16 Յ l Յ 16
231
number of images
exposure time
detector distance
absorption correction
μ
2.00 min
1.20 min
70 mm
numerical
84.13 cmϪ1
O11
O12
O13
N2
79.91 cmϪ1
18052
2832
measured reflections
unique reflections
17615
2770
2542
0.0845; 0.0413
reflections with I0 > 2σ(I0) 2578
int; Rσ 0.0385; 0.0219
R
structure determination and
refinement
scattering factors
SHELXS97 and SHELXL97
O21
O22
O23
O7
Intern. Tables, Vol. C [11]
0.0014(2)
extinction coefficient
0.00282(9)
goodness of fit (I0 > 2σ(I0)) 0.979
R1; wR2 (I0 > 2σ(I0))
1.291
0.0610;0.1312
0.0659;0.1326
0.0137;0.0267
R1; wR2 (all data)
0.0169;0.0271
Ϫ3
Ϫ3
˚
˚
max./min. residual electron 0.512/Ϫ0.399 A
3.193/Ϫ2.735 A
density
ICSD
a)
U
ϭ 1/3 [U22 ϩ 1/sin2β(U11 ϩ U33 ϩ 2U13cos β)] [12]
eq
418135
415843
Fig. 1 Coordination polyhedron of the M3ϩ ions in the crystal
structure of [M(NO3)2(H2O)6]2[PtCl6]·2H2O (M ϭ La, Pr)
Fig.
2
Perspective view of the crystal structure of
Also in the crystals structures of the isotypic compounds
[M(NO3)(H2O)7][PtCl6]·4H2O (M ϭ Gd, Dy) octahedral
[PtCl6]2Ϫ anions are found showing almost the same dis-
tances (232-233 pm, cf. table 5) as described above for the
lanthanum and praseodymium compound, respectively.
However, in this case charge balance is achieved by complex
[M(NO3)(H2O)7]2ϩ cations (M ϭ Gd, Dy). The nitrate
group is coordinated in a chelating manner leading to a
coordination number of nine for the metal atoms (Fig. 3).
[M(NO3)2(H2O)6]2[PtCl6]·2H2O (M ϭ La, Pr)
The coordination polyhedron is a trigonal prism, but in
contrast to the findings for the [M(NO3)2(H2O)6]ϩ ions
only two of the three rectangular faces are capped. Again,
one oxygen atom is located above one of the prism edges.
The distances M-O range from 239 to 257 pm and from 236
to 257 pm for M ϭ Gd and Dy, respectively. The average
432
www.zaac.wiley-vch.de
© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
Z. Anorg. Allg. Chem. 2008, 431Ϫ435

Hexachloroplatinates of the Lanthanides
Table 3 Selected internuclear distances (in pm) and angles (in °)
for [M(NO3)2(H2O)6]2[PtCl6]·2H2O (M ϭ La, Pr)
Table
4
Crystal data and structure refinement of
[M(NO3)(H2O)7)][PtCl6]·4H2O (M ϭ Gd, Dy)
[La(NO3)2(H2O)6]2[PtCl6]·
2H2O
[Pr(NO3)2(H2O)6]2[PtCl6]·
2H2O
[Gd(NO3)(H2O)7][PtCl6]· [Dy(NO3)(H2O)7][PtCl6]·
4H2O
4H2O
M1
-O1
-O2
-O3
-O4
-O5
-O6
-O11
-O12
-O21
-O22
252.9(2)
257.1(2)
249.2(2)
256.9(2)
253.0(2)
265.7(2)
278.2(2)
262.6(2)
273.6(2)
262.7(2)
252(1)
254(1)
247(1)
257(1)
250(1)
258(1)
275(1)
257(1)
271(1)
257(1)
lattice parameter
a ϭ838.72(3) pm
b ϭ2131.98(6) pm
c ϭ1142.63(3) pm
β ϭ 95.670°(4)
2033.2(1) A
2.696
a ϭ838.40(2) pm
b ϭ2139.50(7) pm
c ϭ1143.10(3) pm
β ϭ 95.698°(3)
2040.3(1) A
2.704
3
3
˚
˚
cell volume
density (calcd.) /(g/cm3)
number of formula units
crystal system
space group
4
monoclinic
P21/n (no. 14)
Stoe IPDS I
diffractometer
radiation
temperature
Mo-Kα (graphite monochrom., λ ϭ 71.07 pm)
153 K
200 K
л 261.2(2)
л 257.8(1)
θ range
3.3° < 2θ < 52.1°
Pt1
N1
N2
-Cl11
-Cl12
-Cl13
234.14(6) (2x)
232.55(7) (2x)
233.04(6) (2x)
233.5(3) (2x)
232.1(4) (2x)
232.8(4) (2x)
rotation range, ϕ increment 0° < ϕ < 240.0°, 1.0°
index range
0° < ϕ < 300.0°, 1.0°
Ϫ9 Յ h Յ 9
Ϫ26 Յ k Յ 26
Ϫ13 Յ l Յ 14
300
Ϫ10 Յ h Յ 10
Ϫ26 Յ k Յ 26
Ϫ13 Յ l Յ 14
240
-O11
-O12
-O13
127.8(3)
127.5(3)
123.3(3)
127(2)
126(2)
122(1)
number of images
exposure time
detector distance
absorption correction
μ
2 min
1 min
70 mm
numerical
113.23 cmϪ1
-O21
-O22
-O23
127.5(3)
128.2(3)
122.8(3)
130(2)
126(2)
123(2)
109.50 cmϪ1
19198
3957
measured reflections
unique reflections
24429
3799
Cl13-Pt1-Cl13
Cl12-Pt1-Cl11
Cl12-Pt1-Cl11
Cl13-Pt1-Cl11
Cl13-Pt1-Cl11
Cl11-Pt1-Cl11
180
180
reflections with I0 > 2σ(I0) 3335
int; Rσ 0.0618;0.0385
3375
0.0496;0.0245
88.39(2)
91.61(2)
90.29(2)
89.71(2)
180
88.8(2)
91.2(2)
90.4(2)
89.6(2)
180
R
structure determination and
refinement
SHELXS97 and SHELXL97
scattering factors
Intern. Tables, Vol. C
0.00078(9)
extinction coefficient
0.00048(6)
goodness of fit (I0 > 2σ(I0)) 1.173
R1; wR2 (I0 > 2σ(I0))
1.082
0.0295; 0.0810
0.0337; 0.0858
O13-N1-O11
O13-N1-O12
O11-N1-O12
121.9(2)
121.3(2)
116.9(2)
122(2)
121(2)
117(2)
0.0384; 0.0870
R1; wR2 (all data)
0.0475; 0.0892
Ϫ3
Ϫ3
˚
˚
max./min. residual electron 1.463/Ϫ2.021 A
1.599/Ϫ2.181 A
density
N1-O11-M1
N1-O12-M1
93.9(1)
101.5(1)
92.6(8)
101.7(8)
ICSD
416470
416472
O2-M1-O6
125.14(7)
137.45(6)
131.79(6)
47.93(5)
64.96(6)
72.98(6)
106.63(6)
47.34(6)
124.0(4)
139.2(4)
131.3(4)
48.3(3)
63.9(4)
71.5(4)
107.2(4)
47.7(3)
O12-M1-O6
O12-M1-O21
O22-M1-O21
O6-M1-O21
O3-M1-O11
O2-M1-O11
O12-M1-O11
distance is slightly shorter for the dysprosium compound in
accordance with the smaller ionic Dy3ϩ radius. The
[M(NO3)(H2O)7]2ϩ and the [PtCl6]2Ϫ anions are arranged
into layers in the crystal structure that alternate in the [010]
direction (Fig. 4). Between these layers four non-bonded
water molecules per unit cell are located. They are linked
to H2O molecules of the [M(NO3)(H2O)7]2ϩ cations by hy-
drogen bonds showing donor-acceptor distances between
270 and 290 pm.
Thermal Behaviour
The thermal behaviour of the hexachloroplatinates under
investigation is very complex. The decomposition is shown
for the example of the praseodymium compound in Fig-
ure 5. For all of the four compounds at least seven steps
can be seen in the DTA/TG diagram (Table 7). With respect
to the observed mass losses it is difficult to assign inter-
mediates for all of these steps. However, it is certain that
the final product of the decomposition is elemental plati-
num and the respective oxide chlorides MOCl (M ϭ La, Pr,
Gd, Dy). This is in accordance with the total mass loss
(Table 7) and has been confirmed by X-ray powder diffrac-
Fig. 3 Coordination polyhedron of the M3ϩ ions in the crystal
structure of [M(NO3)(H2O)7][PtCl6]·4H2O (M ϭ Gd, Dy)
Z. Anorg. Allg. Chem. 2008, 431Ϫ435
© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
www.zaac.wiley-vch.de
433

A. Arndt, D. Posavec, S. Schwarzer, M. S. Wickleder
Table 5 Atom positions and equivalent thermal displacement
parameters for [M(NO3)(H2O)7][PtCl6]·4H2O (M ϭ Gd, Dy)
Table 6 Selected internuclear distances /pm and angles /° for
[M(NO3)(H2O)7][PtCl6]·4H2O (M ϭ Gd, Dy)
2
a)
˚
atom
Wyckoff
x/a
y/b
z/c
Ueq. / A
[Gd(NO3)(H2O)7][PtCl6]·
4H2O
[Dy(NO3)(H2O)7][PtCl6]·
4H2O
Gd1
Dy1
Pt1
4e
4e
4e
4e
4e
4e
4e
4e
4e
4e
4e
4e
4e
4e
4e
4e
4e
4e
4e
4e
4e
4e
4e
4e
4e
4e
4e
4e
4e
4e
4e
4e
4e
4e
4e
4e
4e
4e
4e
4e
4e
4e
4e
4e
4e
4e
0.28022(4)
0.27961(3)
0.76480(3)
0.76095(2)
1.0364(2)
1.0324(2)
0.7413(2)
0.7379(2)
0.7029(3)
0.6993(2)
0.8294(3)
0.8247(2)
0.4943(2)
0.4906(2)
0.7827(2)
0.7803(2)
0.3677(7)
0.3666(7)
0.5209(7)
0.5169(6)
0.2169(8)
0.2152(6)
0.2599(7)
0.2610(6)
0.2719(8)
0.2715(6)
0.2048(8)
0.2069(6)
0.5149(8)
0.5119(6)
0.9290(8)
0.9306(6)
0.0211(7)
0.0205(6)
0.9923(7)
0.9957(6)
0.7829(6)
0.7821(6)
0.9707(8)
0.9738(6)
0.9735(7)
0.9751(6)
0.0530(8)
0.0510(6)
0.0465(7)
0.0469(6)
0.24380(2)
0.24523(1)
0.00134(1)
0.001002(7)
0.97898(9)
0.97837(7)
0.01091(9)
0.01023(6)
0.89570(8)
0.89546(6)
0.10630(9)
0.10601(6)
0.02518(9)
0.02485(7)
0.99349(9)
0.99303(6)
0.2484(3)
0.2486(2)
0.3031(3)
0.3043(3)
0.3510(3)
0.3502(2)
0.3061(3)
0.3068(2)
0.1712(3)
0.1742(2)
0.1412(3)
0.1440(2)
0.1759(3)
0.1783(2)
0.2486(3)
0.2490(2)
0.2511(3)
0.2507(2)
0.2448(3)
0.2457(2)
0.2493(3)
0.2494(2)
0.1363(3)
0.1372(2)
0.3647(3)
0.3638(2)
0.1056(3)
0.1059(2)
0.4022(3)
0.4003(2)
0.31670(3)
0.31383(2)
0.24830(3)
0.24890(2)
0.2502(2)
0.2502(1)
0.0444(2)
0.0449(1)
0.2328(2)
0.2340(1)
0.2658(2)
0.2655(1)
0.2465(2)
0.2476(1)
0.4513(2)
0.4522(1)
0.1243(6)
0.1236(4)
0.3606(7)
0.3546(5)
0.2571(6)
0.2532(4)
0.4934(5)
0.4878(4)
0.4773(6)
0.4739(4)
0.2357(6)
0.2361(4)
0.3292(7)
0.3289(5)
0.2578(6)
0.2539(4)
0.1778(5)
0.1739(4)
0.3614(5)
0.3589(4)
0.2347(6)
0.2316(4)
0.5420(6)
0.5387(4)
0.5261(6)
0.5260(4)
0.0267(6)
0.0274(4)
0.0632(6)
0.0566(4)
0.0103(1)
0.0131(1)
0.0100(1)
0.0122(1)
0.0169(4)
0.0243(3)
0.0175(4)
0.0205(3)
0.0162(4)
0.0202(3)
0.0196(5)
0.0232(3)
0.0186(4)
0.0246(3)
0.0172(4)
0.0195(3)
0.022(1)
0.025(1)
0.029(2)
0.039(1)
0.021(1)
0.025(1)
0.018(1)
0.027(1)
0.023(1)
0.033(1)
0.020(1)
0.0238(9)
0.029(2)
0.042(1)
0.012(1)
0.011(1)
0.018(1)
0.020(1)
0017(1)
0.0203(9)
0.017(1)
0.0186(9)
0.023(1)
0.027(1)
0.019(1)
Pt1
-Cl11
-Cl12
-Cl13
-Cl14
-Cl15
-Cl16
232.6(2)
232.7(2)
231.4(2)
230.6(2)
232.3(2)
231.6(2)
232.6(2)
232.9(1)
231.9(1)
231.3(1)
232.2(2)
232.0(1)
Cl11
Cl12
Cl13
Cl14
Cl15
Cl16
O1
N2
-O21
-O22
-O23
125.5(9)
125.0(9)
122.8(9)
124.2(7)
127.0(7)
124.6(7)
M1
-O1
-O2
-O3
-O4
-O5
-O6
-O7
-O21
-O22
238.7(6)
239.3(6)
242.9(6)
243.7(6)
240.7(6)
243.5(6)
243.6(6)
256.6(6)
251.7(6)
236.2(5)
236.4(5)
239.5(4)
240.4(4)
238.6(4)
239.6(4)
241.0(5)
256.9(5)
248.5(5)
O2
O3
O4
O5
л 244.5(6)
л 241.9(5)
O6
Cl14-Pt1-Cl13
Cl13-Pt1-Cl16
Cl13-Pt1-Cl15
179.17(8)
89.89(7)
90.05(7)
179.34(5)
89.70(5)
90.19(5)
O7
N2
O21
O22
O23
O8
O23-N2-O22
O23-N2-O21
O22-N2-O21
121.7(7)
121.0(7)
117.2(6)
121.4(5)
121.1(5)
117.5(5)
O1-M1-O2
O1-M1-O5
O2-M1-O5
O2-M1-O4
O1-M1-O7
O1-M1-O2
80.9(2)
139.8(2)
105.5(2)
70.4(2)
76.0(2)
125.1(2)
80.5(2)
139.5(2)
106.1(2)
70.5(2)
76.3(2)
125.5(2)
O9
0.0228(9)
0.023(1)
0.027(1)
0.023(1)
O10
O11
0.031(1)
a)
U
ϭ 1/3 (U22ϩ1/sin2β(U11ϩU33 ϩ2U13cosβ)] [12]
eq
tion (STOE STADIP). The first steps of the decompositions
are obviously correlated with the loss of water and they
start at quite low temperatures in accordance with the ob-
servation that the compounds seem to loose water even at
ambient conditions. It is not possible to distinguish between
the loss of crystal water molecules and coordinated water
molecules because no significant plateaus in the TG curves
occur. Above 220 °C the decompositions parallel the re-
ported decomposition of PtCl4 [4]. Thus, it can be assumed
that PtCl4 is formed as an intermediate, and that the degra-
dation above 220 °C is stamped by the formation of the
lower platinum chlorides PtCl3 (ϭ PtIIPtIVCl6) and PtCl2,
and finally elemental Pt. Consequently, the formation of the
oxide-chlorides MOCl is complete at 220 °C. It is note-
worthy to point out that the platinates under investigation
are suitable precursors for the formation of elemental plati-
num particles in a lanthanide oxide chloride matrix. Investi-
gations of the particle shape and their distribution in the
matrix are currently in progress.
Fig.
and
4
Layered arrangement of the [M(NO3)(H2O)7]2ϩ
[PtCl6]Ϫ
ions in the crystal structure of
[M(NO3)(H2O)7][PtCl6]·4H2O (M ϭ Gd, Dy)
434
www.zaac.wiley-vch.de
© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
Z. Anorg. Allg. Chem. 2008, 431Ϫ435

Hexachloroplatinates of the Lanthanides
evaporation of a solution of 576 mg Gd(NO3)3 ·5H2O (583 mg
Dy(NO3)3 ·5H2O) in aqueous (H3O)2PtCl6. The compounds are
hygroscopic, but when placed in a desiccator the crystals turned
cloudy, probably due to the loss of crystal water.
For each compound several single crystals were fixed onto glass
fibres and checked with the help of an image plate diffractometer
(STOE IPDS). For the respective best specimen diffraction data
were collected with the same diffractometer. The crystal structures
were solved applying direct methods (program SHELXS93 [5]) and
refined using the program SHELXL93 [6]. The absorption correc-
tion has been performed numerically with the help of the programs
X-Shape and X-Red [7, 8]. The crystallographic data and their
determination are summarized in the tables 1-6. Further details are
available from the Fachinformationszentrum Karlsruhe, D-76344
Eggenstein-Leopoldshafen (crysdata@FIZ-Karlsruhe.de) on quot-
ing the deposition numbers given in the tables.
Fig. 5 Thermal decomposition of
[Pr(NO3)2(H2O)6]2[PtCl6]·2H2O
For the investigation of the thermal behaviour of the four com-
pounds about 15 mg of each chloroplatinate were placed in a cor-
undum crucible. The decomposition was monitored using the ther-
moanalyzer TGA/SDTA 851E (METTLER-TOLEDO). The data
were processed using the software supplied with the analyzer [9].
The relevant data are summarized in table 7.
Table
7
Data
of
the
thermal
decomposition
of
[La(H2O)6(NO3)2]2[PtCl6]·2H2O, [Pr(H2O)6(NO3)2]2[PtCl6]·2H2O,
[Gd(NO3)(H2O)7][PtCl6]·4H2O, and [Dy(NO3)(H2O)7][PtCl6]·4H2O.
[La(H2O)6(NO3)2]2[PtCl6]·2H2O [Pr(H2O)6(NO3)2]2[PtCl6]·2H2O
X-ray powder diffraction was carried out on the residues of
the thermal decompositions with the help of the diffractometer
STADI P (STOE) using Cu-Kα radiation. Assignment of the
observed patterns was carried out using the reported data of the
tetragonal oxide chlorides MOCl (M ϭ La, Pr, Gd, Dy), for ex-
ample in [10], and platinum (PDF number 4-802).
Step
Tonset(°C) Tend(°C) Tmax(°C) Tonset(°C) Tend(°C) Tmax(°C)
1
2
3
4
5
6
7
61.4
98.2
162.5
292.0
343.1
435.8
491.1
98.2
88.0
55.9
107.9
158.9
243.2
351.9
401.0
472.7
574.9
79.0
162.5
216.1
343.1
435.8
491.2
571.4
118.6
196.3
329.4
376.1
454.0
531.3
107.9
158.9
243.2
351.9
401.0
472.7
136.1
187.1
312.9
360.0
439.8
534.2
Acknowledgement. We thank Mr. Wolfgang Saak for collecting the
X-ray data. D. P. is indebted to the DAAD for a stipend.
Mass loss Σ
Mass loss Σ
53.1 %
54.7 %
Obs.
Calc.
Σ
Σ
52.3 %
51.8 %
Obs.
Calc.
References
[1] F. Rau, U. Klement, K.-J. Range, Z. Kristallogr. 1995, 210,
684.
Step
[Gd(NO3)(H2O)7][PtCl6]·4H2O [Dy(NO3)(H2O)7][PtCl6]·4H2O
1
2
3
4
5
6
7
60.6
141.4
233.3
274.9
352.9
416.1
513.2
572.7
101.3
196.0
240.1
335.9
378.0
503.0
547.5
66.8
153.5
199.9
247.4
297.9
358.2
498.6
587.2
78.9
[2] G. Bauer (ed.), Handbuch der Präparativen Anorganischen
Chemie, F. Enke Verlag, Stuttgart (1975).
[3] M. S. Wickleder, I. Müller, G. Meyer, Z. Anorg. Allg. Chem.
2001, 627, 4.
[4] A. E. Schweizer, G. T. Kerr, Inorg. Chem. 1978, 17, 2326.
[5] G. M. Sheldrick, SHELXS-93, Program for the Solution of
Crystal Structures Göttingen 1993.
[6] G. M. Sheldrick, SHELXL-93, Program for Crystal Structure
Refinement, Göttingen 1993.
173.1
233.3
274.9
352.9
416.1
513.2
153.5
199.9
247.4
297.9
358.2
498.6
178.4
234.9
265.7
336.7
484.0
542.8
Mass loss Σ
Mass loss Σ
51.6 %
51.1 %
Obs.
Σ
Σ
50.7 %
50.8 %
Obs.
Calc.
Calc.
[7] Fa. STOE & Cie, X-RED 1.07, Data Reduction for STADI4
and IPDS, Fa. STOE Cie, Darmstadt 1996.
[8] X-SHAPE 1.01, Crystal Optimisation for Numerical Absorp-
tion Correction, Fa. STOE & Cie, Darmstadt 1996.
[9] STARe, Thermal analysis for the analyzer TGA/SDTA 851E,
version 8.1, Mettler-Toledo GmbH, Schwerzenbach, Ger-
many, 2004.
[10] L. H. Brixner, E. P. Moore, Acta Crystallogr. 1983, 39, 1316;
G. Meyer, Th. Schleid, Z. Anorg. Allg. Chem. 1986, 533, 181.
[11] Th. Hahn (ed.), International Tables for Crystallography, Vol.
C, D. Reidel Publishing Company, Dordrecht, Boston (1983).
[12] R. X. Fischer, E. Tillmanns, Acta Crystallogr. 1988, C44, 775.
Experimetal Section
(H3O)2PtCl6 has been obtained according to the literature
procedure given in [2]. Yellow single crystals of
[M(NO3)2(H2O)6]2[PtCl6]·2H2O (M ϭ La, Pr) were prepared by
evaporation of a solution of 827 mg La(NO3)3 ·6H2O (713 mg
Pr(NO3)3 ·6H2O) in aqueous (H3O)2PtCl6.
Yellow
coloured,
rod
shaped
single
crystals
of
[M(NO3)(H2O)7][PtCl6]·4H2O (M ϭ Gd, Dy) were prepared by
Z. Anorg. Allg. Chem. 2008, 431Ϫ435
© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
www.zaac.wiley-vch.de
435