[
M(NH ) CL][AuCL ]CL · nH O (M = Rh, Ru, OR Cr)
1725
3
5
4
2
IR spectra were recorded as KBr disks on Scimitar weight during subsequent storage in air. Comparison of
–
1
FTS 2000 in the range 400–4000 cm .
X-ray powder diffraction data for hydrous and anhy-
drous samples of the double complex salt implies that
the unit cell parameters change noticeably as a result of
elimination of crystal water (Table 5). Heating
3 5 4 2
partial degradation even under an inert atmosphere.
Thermogravimetric measurements were carried out
on a Q-1000 derivatograph updated for operating with
various gas atmospheres (air or helium). A test sample
~100 mg) was placed in a quartz crucible and heated at
0 K/min in a helium flow (150 mL/min). Thermo-
[
Ru(NH ) Cl][AuCl ]Cl ꢀ nH O to 150°ë causes its
(
1
gravimetric experiments were also carried out on a
Netzsch STA 409 PC Luxx derivatograph (heating at
Structure of [Rh(NH ) Cl][AuCl ]Cl ꢀ 0.5H O (1)
3
5
4
2
1
0 K/min, helium, Al O crucible).
2 3
2+
Structural units are [Rh(NH ) Cl] complex cations
3
5
X-ray diffraction experiments were carried out on a
–
–
and two types of anions ([AuCl ] and Cl ). Figure 1
DRON-Seifert-RM4 diffractometer (CuK radiation,
4
α
shows the structure of complex ions with atom number-
ing.A complex cation has symmetry m, Rh–N distances
average 2.065 Å, the Rh–N bond length in the trans-
position to Cl is 2.054 Å, the Rh–Cl distance is 2.342 Å,
and the deviation of bond angles from 90° does not exceed
graphite monochromator in the reflected beam, scintil-
lation detector with amplitude discrimination). Test
samples were ethanolic suspensions spread over the
polished side of a standard quartz cell. The external ref-
erence was a polycrystalline silicon sample (a = 5.4309 Å)
prepared in the same way. X-ray diffraction patterns for
1
.9°. These parameters agree with literature data for com-
2+
double complex salts were recorded in a step mode in pounds containing [Rh(NH ) Cl] cations, for example,
3 5
the range 2θ 5°–60°; those for thermolysis products, in [Rh(NH ) Cl]Cl [8] and [Rh(NH ) Cl] [MCl ]Cl where
3
5
2
3 5
2
6
2
the range 2θ 5°–135°.
M = Co, Rh, or Ir [9].
X-ray diffraction patterns for thermolysis products
were indexed with reference to data on pure metals and
compounds in the PDF File [5]. The unit cell parame-
ters of metallic phases were refined by the least-squares
method for the entire data set using PowderCell 2.4
software [6].
Two crystallographically independent [AuCl4]–
complex anions have symmetry 2/m. The coordination
polyhedra around gold atoms are almost regular
squares; the difference in Au–Cl distances does not
exceed 0.005 Å; ClAuCl bond angles are practically
9
0°. The planes of the Au(1) and Au(2) coordination
For
Ru(NH ) Cl][AuCl ]Cl ꢀ nH O, X-ray diffraction pat-
[Rh(NH ) Cl][AuCl ]Cl
ꢀ
nH O
and squares are perpendicular.
3
5
4
2
[
3
5
4
2
The square coordination of the Au(1) atom is made an
terns were indexed with reference to single-crystal
data, and they verified that the products were single
phases.
–
elongated bipyramid, being supplemented with two Cl
counterions with an Au···Cl distance of 3.221 Å. The near-
est axial positions to the Au(2) atom are occupied by dis-
Unit cell parameters and experimental intensities for ordered water molecules at distances of 2.95 Å.
the solution of crystal structures were measured on a
Bruker-Nonius X8APEX automated four-circle diffrac-
Figure 2 shows the general view of the crystal struc-
ture in the direction of axis y. The structure is layered,
as indicated by the platelike crystal shape. Complex
tometer equipped with a planar detector (MoK radia-
α
tion, graphite monochromator). The crystallographic
parameters of the test compounds and details of X-ray
diffraction experiments are listed in Table 1. The struc-
tures were solved by a direct method and refined in the
anisotropic (for H atoms, isotropic) approximation. The
positional parameters of atoms are listed in Table 2;
selected interatomic distances and bond angles are in
Table 3. The SHELX 97 program package [7] was used
in all calculations.
3
cations form hexagonally packed layers 6 lying normal
to axis x with Rh···Rh distances of 6.635–7.794 Å. The
Cl(6) counterions lie in the same layers and are H-
bonded to complex cations as Cl···ç–N with Cl···N dis-
tances estimated at 3.18–3.48 Å (Fig. 2). Gold com-
plexes are packed into anionic layers with Au···Au dis-
tances of 6.836 and 7.794; we should mention a short
ël···Cl intermolecular contact (3.23 Å). Layers of com-
plex cations and layers of complex anions alternate in
the direction [100] and are bonded via weak H-bonds.
The shortest six Rh···Au distances in the structure are
within 5.787–6.043 Å.
RESULTS AND DISCUSSION
The test compounds are isostructural to
Figure 3 displays thermoanalytical curves for the
[
Ir(NH ) Cl][AuCl ]Cl, which we studied earlier, how-
3 5 4
thermolysis of [Rh(NH ) Cl][AuCl ]Cl ꢀ 0.5H O in a
3
5
4
2
ever, containing molecules of water of crystallization.
The presence of water is verified by IR spectra
helium atmosphere. The compound decomposes in two
steps: one at 250–350°ë and the second at 350–410°ë;
both are accompanied by endotherms. Weight loss at
the first step is 23.8 wt %; at the second, 26.7 wt %.
Overall weight loss is 50.5 wt %, corresponding to the
(
Table 4) and thermogravimetric measurements. The
water content in polycrystalline samples is 0.3 ≤ n ≤ 0.8
and can vary from synthesis to synthesis.
Notably [Rh(NH ) Cl][AuCl ]Cl ꢀ nH O samples AuRh stoichiometry of the residue. The final product is
3
5
4
2
dehydrated under heating to 150°ë do not change their a two-phase powder of nanosized gold and rhodium
RUSSIAN JOURNAL OF INORGANIC CHEMISTRY Vol. 53 No. 11 2008