Solid-phase room-temperature decomposition of a complex salt trans-[Rh(γ-Pic)4Cl2]MnO4

Article abstract of DOI:10.1016/j.poly.2011.01.025

Permanganate salt of the complex cation trans-[Rh(γ-Pic) ₄Cl₂]⁺ (γ-Pic = γ-picoline) was synthesized. The unusual decomposition reaction of the salt was studied at room temperature. This process has been found to conserve the γ-picoline ligands in cation untouched. A number of transformations in anionic part of salt have been observed. Metallic products of the salt thermal decomposition have been studied.

Full text of DOI:10.1016/j.poly.2011.01.025

Polyhedron 30 (2011) 1201–1206
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Polyhedron
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Solid-phase room-temperature decomposition of a complex salt
trans-[Rh(c-Pic) Cl ]MnO
4
2
4
⇑
Anatoliy B. Venediktov , Danila B. Vasilchenko, Irina V. Yushina, Tatyana I. Nedoseykina,
Evgeniy Yu. Filatov, Sergey V. Korenev
Nikolaev Institute of Inorganic Chemistry SB RAS, 630090 Novosibirsk, Russia
a r t i c l e i n f o
a b s t r a c t
+
Article history:
Received 11 December 2010
Accepted 20 January 2011
4 2
Permanganate salt of the complex cation trans-[Rh(c-Pic) Cl ] (c-Pic = c-picoline) was synthesized. The
unusual decomposition reaction of the salt was studied at room temperature. This process has been
found to conserve the -picoline ligands in cation untouched. A number of transformations in anionic
c
part of salt have been observed. Metallic products of the salt thermal decomposition have been studied.
Ó 2011 Elsevier Ltd. All rights reserved.
Keywords:
Rhodium complexes
Picoline
Permanganate
Manganese dioxide
Nanoparticles
Nanoalloys
1
. Introduction
Complexes of rhodium(III) with pyridine and its substituted
In the present work, we have studied an uncommon solid-state
room-temperature decomposition reaction of aforesaid permanga-
nate salt. In addition, final products of thermal decomposition of
the salt have been studied.
derivatives are of large interest in different branches of chemical
science due to their unusual and useful properties. Such complexes
are precursors of active catalysts for water–gas shift, hydrogena-
tion, hydroformylation, carbonylation of methanol and other re-
lated reactions [1]. Unprecedented antibacterial and antitumor
activity was found for the complexes of rhodium(III) with methyl-
pyridines [2]. Trans-[RhL
peared useful for isolation of unusual anionic species in the form
of stable adducts [3]. In our recent work [4] the cation trans-
2
. Experimental
The salt [Rh(
described previously [4] from commercial ‘rhodium chloride’ of
composition RhCl O. All employed solvents and reagents were
c
-Pic)
4
Cl
2
2
]Clꢁ2.5H O was prepared by the method
+
4
Cl
2
]
cations (L = Py or
c-picoline) ap-
3
ꢁ3H
2
of analytical grade and were used without further purification. Ele-
mental CHN-analyses were performed with Euro EA 3000 analyzer.
+
[
Rh(
4
c-Pic) Cl
2
] was used for examination of methyl group oxida-
Solid state IR spectra were measured with a Scimitar FTS 2000
tion in coordinated
coordination core. This oxidation was carried out with KMnO
the oxidant, and a poorly soluble salt trans-[Rh( -Pic) Cl ]MnO
is initially formed, which rapidly decomposes in boiling solution.
The decomposition of the salt was observed under darkroom
conditions at room temperature as well. Several ways for
decomposition of MnO
complex and simple inorganic cations, but they require either
thermal- [5] or photoactivation [6] to achieve high reaction rate.
Therefore, the above-mentioned rapid decomposition of
c-picoline without destruction of the [RhN
Cl
4 2
]
ꢀ1
(
4000–400 cm , KBr pellets) spectrometer and Vertex 80 IR-FT
4
as
ꢀ1
spectrometer (400–100 cm , PE pellets).
c
4
2
4
UV–Vis spectra were recorded with a Shimadzu UV-3101 PC
spectrometer. Diffuse reflectance spectroscopy was carried out
with Shimadzu UV–Vis–NIR spectrometer UV-3101 PC using BaSO
as a reference. The reflectance spectra were recorded in 240–
4
ꢀ
4
are known for solid salts involving both
8
00 nm range.
A Bruker AVANCE 500 (AV500) spectrometer was used in order
13
to obtain C nuclear resonance spectra with d
6
-acetone as a
reference.
trans-[Rh(
the nature of such instability.
4 2 4
c-Pic) Cl ]MnO requires deeper study to understand
Differential thermal analysis of the synthesized compound was
carried out with a TG 209 F1 IrisÒ (NETZSCH) in He stream (70 ml/
min) at heating rate 10 K/min.
⇑
Corresponding author. Tel.: +7 383 3165633; fax: +7 383 3309489.
E-mail address: venedik@niic.nsc.ru (A.B. Venediktov).
X-ray diffraction study of polycrystalline samples was carried
out on DRON-SEIFERT-RM4 diffractometer (Cu Ka – radiation
0
277-5387/$ - see front matter Ó 2011 Elsevier Ltd. All rights reserved.
doi:10.1016/j.poly.2011.01.025

1
202
A.B. Venediktov et al. / Polyhedron 30 (2011) 1201–1206
(
k = 1.5418 Å), graphite monochromator on the diffracted beam,
scintillation detector with amplitude discrimination) in 2h range
–60°. The samples were prepared by deposition of a suspension
2.2. [Rh(
4 2 3
c-Pic) Cl ]HCO
5
To water solution of [Rh(
c
-Pic)
4
Cl
2
]Clꢁ2.5H O (ꢂ0.01 M) was
2
in hexane on the polished side of a quartz sample holder. Similarly
prepared polycrystalline quartz sample (a = 5.4309 Å) was used as
an external standard. Indexing of the diffraction patterns for the
products of thermolysis was carried out using the data for pure
metals and compounds reported in the PDF database [7], 2h range
added quintuple excess of sodium hydrocarbonate. Pale yellow
precipitate was filtered out, recrystallized from acetone, washed
with Et
2 2 4
O. Air-dry salt was kept in dessicator (with conc. H SO )
48 h to obtain anhydrous product. Yield: 90%. IR (KBr): 3080(
m
CAH),
C@O),
3051(
1509(
1333(
m
m
m
CAH), 2953(
C@C), 1439(
m
CAH), 2919(
mCAH), 1621(
mC@N), 1608 (
m
3ꢀ
5
–120° was used. Unit cell parameters were refined by the full-
m
C@C), 1433(
m
C@C), 1371(
m
C@C), 1360(HCO ),
profile technique within the whole diffraction range with the
POWDERCELL 2.4 program [8].
C@C), 1232(dCAH), 1214(dCAH), 1117(dCAH), 1061(dCAH),
ꢀ
1037(dCAH), 810(
c
CAH), 722(
c
CAH), 703(HCO
3
), 565(dring),
Mn K-edge XAFS spectrum of MnO
2
was measured in transmis-
512(dring). Anal. Calc. for C25
H29Cl
2
N
4
O
3
Rh: C, 49.44; H, 4.81; N,
sion mode at Kurchatov centre of synchrotron radiation (Moscow,
Russia). IFFEFIT program suite [9,10] was used for treatment of the
XAFS data. Fitting was done in R-space in the range from 1.0 to
9.22. Found: C, 49.32; H, 8.9; N, 9.1%.
3
.0 Å. EXAFS fit was performed simultaneously in k-weightings of
3. Results and discussion
one, two and three to avoid errors in coordination numbers and
Debye–Waller factors.
3.1. The room-temperature decomposition process
Surface morphologies of the materials were studied using a
transmission electron microscope JEOL JEM-100CX and scanning
electron microscope JSM 6700F with EDS EX-23000 BU.
Addition of KMnO
results in precipitation of low-soluble salt [Rh(
4
to solution of the [Rh(
c
-Pic)
4
Cl
2
]Clꢁ2.5H
2
O
c
-Pic)
4
Cl ]MnO .
2
4
Due to the decomposition reaction during the crystallization our
attempts to grow a single crystal of the salt were unsuccessful
2
.1. [Rh(
c
-Pic)
4
Cl
2
]MnO
4
therefore all synthesized and studied samples of [Rh(
nO are powders of plate crystals (Fig. 1) with size of ca. 5–10
Powder diffraction pattern of the salt was indexed using earlier
published single crystal data for isostructural [Rh( -Pic) Cl ]ReO
4 2
c-Pic) Cl ]M-
4
lm.
Aqueous saturated solution of KMnO
ꢂ0.01 M solution of [Rh( -Pic) Cl ]Clꢁ2.5H
The dark-pink precipitate appeared immediately. Addition of
KMnO was stopped when the mother liquor turned to pale-pink.
The precipitate was collected by filtration, washed with H O and
Et O and dried in air stream (15 min). The yield of the reaction
was ca. 98%. Dry salt was kept in darkness at 0 °C. The compound
is slightly soluble in water, readily soluble in ethanol and
acetone, but substantially reacts with them. IR (KBr): 3083(
4
was added dropwise to
c
4
2
2
O at room temperature.
c
4
2
4
[4]. Unit cell parameters were refined by the full-profile technique
using all diffraction data with Rietveld-Toraya (plate, according
to SEM) preferred orientation model for (0 1 1) plane (Fig. 2).
4
2
2
Cell parameters for permanganate salt (space group P2
11.804(4) Å, b = 11.260(4) Å, c = 21.762(8) Å, b = 103.88(3)°, V =
1
/c, a =
3
2
4 2 4
800.9(4) Å ) are less that parameters of [Rh(c-Pic) Cl ]ReO salt
3
mCAH),
(a = 11.866, b = 11.296, c = 22.049, b = 104.10°, V = 2866.4 Å ) due
3
1
1
8
047(mCAH), 2956(
mCAH), 2922(
m
m
CAH), 1621(mC@N), 1503(m
C@C),
to smaller ion radius of manganese versus rhenium.
444(
m
C@C), 1433(
mC@C), 1370(
C@C), 1336(
m
C@C), 1237(dCAH),
Permanganate salt at room temperature gradually decomposes
with formation of a brown substance. Decomposition occurs both
in daylight and in darkness. The process is accompanied by notable
spectral changes. The evolution of electronic spectrum for a sample
of the salt during 24 h (T = 20 ± 1 °C) is shown in Fig. 3.
4ꢀ
212(dCAH), 1115(dCAH), 1064(dCAH), 1041(dCAH), 902(
13( CAH), 719( CAH), 559(dring), 508(dring).
Due to the decomposition reaction during the crystallization
our attempts to grow a single crystal of the salt were unsuccessful
therefore all synthesized and studied samples of [Rh( -Pic) Cl ]M-
nO are powders of plate crystals with size of ca. 5–10 m (SEM,
Fig. 1).
m
3
(MnO )),
c
c
ꢀ
c
4
2
The bands of MnO4 ion in the region 480–600 nm disappear
4
l
and a broad band at 320–390 nm with a shoulder around 500 nm
is formed. Analogous broad band with shoulder around 500 nm
Fig. 2. Diffraction patterns of [Rh(
4 2 4
c-Pic) Cl ]MnO with indexing according to
Fig. 1. The SEM image of [Rh(
c
-Pic)
Cl
4 2
]MnO
4
salt powder.
[Rh( -Pic) Cl ]ReO crystal structure.
c
4
2
4

A.B. Venediktov et al. / Polyhedron 30 (2011) 1201–1206
1203
4 2 4
Fig. 3. The diffuse reflectance UV–Vis spectra change of [Rh(c-Pic) Cl ]MnO
during the decomposition process. The spectra were recorded after 1, 2, 3, 4, 5, 6
and 12 h from precipitation of the salt.
Fig. 5. Diffraction patterns evolution of [Rh(
c
-Pic)
Cl
4 2
]MnO
4
during initial period of
the decomposition process (only 2h = 8–13° range is shown for clarity).
were observed in spectra of MnO
2
and assigned to the charge
brown residue was carried out (Scheme 1). A sample of the brown
residue obtained on decomposition of the initial salt at room tem-
perature during 2 days was stirred in hot (60 °C) water for about
40 min, a dark-brown precipitate (A) was filtered off and the
resulting solution (B) (pH 10) was evaporated until yellow platelet
crystals formed. The crystals were collected by filtration, washed
with icy water and dried. The IR-spectrum of this compound is
transfer band superimposed on 5
B
1g ? B2g and 5
5
B
1g ? E
5
d–d
g
transitions [11]. There is no evidence of manganate-ion absorption
band in the spectra, thus decomposition of [Rh( -Pic) Cl ]MnO
has different nature than in the case of alkali and alkali-earth met-
als permanganates [5d]. The evolution of intensities of both
2 4
absorption bands (growth for MnO band and decrease for MnO
c
4
2
4
ꢀ
bands) obey the exponential law Fig. 4. Similar changes may be
found in IR spectra of the salt during its decomposition. The band
close to that of [Rh(
tion bands at 1606, 1361 and 700 cm , also observed in the IR
c
-Pic)
4
Cl
2
]Clꢁ2.5H
2
O with exception for adsorp-
ꢀ
1
ꢀ
1
ꢀ
4
)) disappears and a broad band in 550–
at 902 cm
4
(
m
3
(MnO
spectrum of the decomposition product (Fig. 6). The first one over-
laps with the band of C N stretching vibrations. The described
@
ꢀ
1
00 cm region arises. In addition, a strong broad band appears
at 3400 cm . Initial diffraction pattern of [Rh(
ꢀ
1
c
-Pic)
4
Cl
2
]MnO
4
bands are observed in spectra of hydrocarbonates and were as-
ꢀ
during first 8–10 h of the decomposition process survives but
practically all peaks shift in small-angle range for ca. 0.4° (Fig. 5).
Further evolution of decomposition process results in formation
of totally X-ray-amorphous powder with diffuse broad peaks like
signed to stretching vibration in HCO
IR-bands miss if CO
3
anions [12]. These addition
2
-free atmosphere is used during the decompo-
sition. Elemental analysis gives reasons to consider the obtained
compound as hydrocarbonate due to good agreement with
it takes place in case of fully amorphous products of AgMnO
4
[Rh(
c
-Pic)
4
Cl
2
]HCO
3
ꢁ1.8H
2
O composition (Anal. Calc. C, 46.94; H,
decomposition at 110 °C [5d]. Aforesaid peaks shift suggests signif-
icant increasing of interplanar spacings and unit cell volume of
source salt before full collapse. In addition it should be noted that
5.13; N, 8.76. Found: C, 46.9; H, 5.0; N, 9.2%). Titration of the com-
pounds with 0.1 M hydrochloric acid gives a typical single-step
titration curve of a hydrocarbonate salts (equivalence points is
about pH 4). Aforesaid hydrocarbonate formula was confirmed
[
4
Rh(c-Pic) Cl
2
]MnO
4
4 2 3
salt prepared from [Rh(c-Pic) Cl ]NO
undergoes the same transformation with identical rate.
In order to investigate the processes taking place during
decomposition of the permanganate salt, an experiment with the
by determination of the molecular mass of this compound based
+
on measured extinction of [Rh(
c
4
-Pic) Cl
2
]
at 402 nm
ꢀ1
ꢀ1
(86.8 l mol cm ). The value deviates from theoretical for
Fig. 4. Showing of course of adsorption maxima at 300 (MnO
2
) and 527 nm
Scheme 1. Sequence of transformation of the permanganate salt described in the
paper. Products of the room-temperature decomposition are shown in dash box.
ꢀ
(
MnO
4
) during the salt decomposition process.

1
204
A.B. Venediktov et al. / Polyhedron 30 (2011) 1201–1206
EXAFS-parameters for the sample are very similar to those for an
electrodeposited manganese oxide [11].
Rh( -Pic) Cl ]MnO slowly decomposes in several weeks when
[
c
4
2
4
kept in vacuum. Product of vacuum decomposition exhibits several
extra bands in IR-spectrum in comparison with IR-spectrum of air-
decomposed salt. These bands lie in region of the C
A
H and the CAC
bonds stretching vibration of
product of ligand oxidation.
c-Pic and so can be assigned with
Thus, during solid-state room-temperature [Rh(
c
-Pic)
4
Cl
2
]M-
ꢀ
nO
4
decomposition MnO
4
ion is reduced to MnO
2
. On the other
ꢀ
ꢀ
hand, the presence of HCO
capturing CO
tion of the decomposition process seems probable:
3
ion indicates the formation of OH
2
from air. Under such conditions the following equa-
4½Rhð
c
-PicÞ Cl
2
ꢃMnO
4
þ 2H
2
O ! 4½Rhð
c
-PicÞ Cl
2
ꢃOH
:
4
4
þ 4MnO
2
þ 3O
2
Fig. 6. IR-spectra of [Rh(
c
4
-Pic) Cl
2
]MnO
4
(a) and product of its decomposition (b).
However, vacuum decomposition experiment shows what oxi-
dation of coordinated picoline takes place but it is low-rate process
in comparison with rate of water-induced reaction. Absorption of
[
Rh(
c
-Pic)
4
Cl
2
]HCO
3
ꢁ1.8H
2
O on 5%, what can be attributed to both
CO
2
4 2
from air by [Rh(c-Pic) Cl ]OH is trivial:
instrumental errors and variable hydrate number of the salt. XRD
pattern of the hydrocarbonate salt samples depends markedly on
its hydrate composition. Diffraction pattern of anhydrous powder
½Rhð
c
-PicÞ Cl
2
ꢃOH þ CO ! ½Rhð
2
c
-PicÞ Cl
2
ꢃHCO
3
:
4
4
is identical to authentic [Rh(
exception of better crystallinity of the latter.
c
-Pic)
4
Cl
2
]HCO
3
pattern with the
4 2
Characterisation of [Rh(c-Pic) Cl ]OH is complicated due to ab-
sence of diffraction pattern from samples of this compound and
easy picoline loss via substitution reaction. Thus CO2 capturing
with formation of the hydrocarbonate salt is useful situation for
detection and separation of rhodium complex from the decompo-
sition products.
Water molecules participating in decomposition process are the
water adsorbed onto the surface of the crystals or are the water of
crystallization. It is difficult to prevent the admixture of such small
amount of water (about 1 mass% for complete decomposition)
during preparation of the salt. Thus, at ambient temperature the
salt decomposes even when stored in a dessicator.
1
3
C NMR spectrum of solution (B) is identical to the spectrum of
+
[
1
Rh(
52.86 ppm (C3), 154.13 ppm (C1)) and does not contain addi-
tional signals. Therefore in three experiments solution (B) was
treated with excess of NaReO and low-soluble [Rh( -Pic) Cl ]ReO
identified by XRD, CHN and IR-spectroscopy) was precipitated.
c
4
-Pic) Cl
2
]
3
cation (20.86 ppm (ACH ), 126.68 ppm (C2),
4
c
4
2
4
(
+
Quantity of [Rh(
4
c-Pic) Cl
2
] cation precipitated in this form corre-
-Pic) Cl ]MnO
98.7%, 99.1%, 99.4% in three particular experiments).
Insoluble dark-brown precipitate (A) is amorphous, and to
sponds with 99% of its initial amount in [Rh(
c
4
2
4
(
study its structure XAFS-spectroscopy [13] was applied. Fourier
The composite material formed after room-temperature
transforms (FT) of the experimental and theoretically calculated
4 2 4
decomposition of [Rh(c-Pic) Cl ]MnO was examined with TEM.
2
Mn K-edge k
v
(k) spectra for the sample are shown in Fig. 7.
As one can see from Fig. 8, nanoparticles of MnO with size about
2
The two strong FT peaks centred at 1.5 and 2.5 Å (phase shift
uncorrected) represent MnAO and MnAMn coordination shells.
According to the data obtained from the fitting procedure, 5.6(5)
oxygen and 3.8(4) manganese atoms occur in the shells with radii
2–3 nm are uniformly distributed in the matrix of the complex.
This matrix provides the stability of the oxide particles of such
small size. The selected-area electron diffraction (SAED) patterns
display several regular highlighted diffraction spots with d = 2.1
ꢀ
1
0
.899(5) Å and 2.890(9) Å, respectively. Debye–Waller factor is
.0026(6) Å
and 2.8 Å which can be indexed to b-MnO . Thus MnO4 anions
2
2
for MnAO and 0.006(1) Å2 for MnAMn.
from source salt after decomposition form particle of MnO phase
2
2
Fig. 7. Mn K-edge XANES spectrum (a) and Fourier transform of k -weigted EXAFS spectrum fitted with FEFF7 theory (- - -) to the data (–––) of sample MnO
2
obtained from
[
4 2 4
Rh(c-Pic) Cl ]MnO salt (b).

A.B. Venediktov et al. / Polyhedron 30 (2011) 1201–1206
1205
Fig. 9. Diffraction pattern of Rh
x
Mn1ꢀx solid solution (a) and products of its
annealing in hydrogen atmosphere at 650 °C (b).
Fig. 8. The TEM image of decomposition products of [Rh(
MnO nanoparticles are shown in white circles.
4 2 4
c-Pic) Cl ]MnO salt.
2
heating results in destruction of the rhodium tetraamine complex.
Thermogram of the salt demonstrates a strong endothermic effect
at 100 °C accompanied by the mass change over 40%, and then
and this process has to be accompanied with intensive diffusion of
Mn-containing particles.
4 2 4
It appears that the reason of [Rh(c-Pic) Cl ]MnO reactivity is
slow destructive oxidation of coordinated c-picolinic ligands takes
the high dispersion of salt samples and big free volume in structure
of salt (packing fraction is about 0.39) simplifying diffusion pro-
cesses during the decomposition.
place in 200–400 °C temperature range. Analogues transformations
were observed in bis(pyridine)silver(I) permanganate and its pyri-
dine solvate [5a]. Thus, picoline molecules can escape untouched
or as the products of its oxidation by MnO
are reduced to metallic form.
2
or rhodium ions which
3.2. A thermally induced decomposition
Total mass loss after heating of the salt up to 650 °C is 72%, and
the final product of thermolysis is Rh Mn1ꢀx solid solution
a = 2.76(1) Å, c = 3.56 Å, space group P4/mmm) and amorphous
carbon. Diffuse form of peaks of the XRD pattern (Fig. 9) suggests
The rate of decomposition of the permanganate salt strongly
depends on temperature. Heating of the salt up to 60 °C results
in rapid (5–10 s) change of its dark-pink colour into brown. Further
x
(
x
Fig. 10. The TEM images of Rh Mn1ꢀx solid solution nanoparticles in carbon matrix.

1
206
A.B. Venediktov et al. / Polyhedron 30 (2011) 1201–1206
a small size of Rh
x
Mn1ꢀx particles (3–8 nm). It is should be noted
energy stimulates high diffusion activity of atoms in phase
transformations and allows surmounting the energy barrier for
growth of a new phase of Rh Mn1ꢀx solid solution.
x
The stabilization of such bimetallic nanoparticles by carbon
produced in decomposition process occurring in the studied sys-
tem is a promising pathway to preparation of analogous particles
of various metals.
that such thermal treatment usually results in sintering of metallic
nanoparticles, and, thus, stabilizing effect of carbon was supposed
for this case. Similar stabilization by carbon shell was observed for
nanoparticles of Co and ZrO
graphs of thermal decomposition products fully confirm this
hypothesis. Particles of Rh Mn1ꢀx solid solution are wrapped in
2
metastable phases [14]. TEM photo-
x
carbon sheets (Fig. 10), which prevent sintering of the particles.
Overall Rh:Mn ratios given by EDS are close to 1:1. In the SAED pat-
terns for several selected particles diffraction spots can be assigned
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4
. Conclusions
Decomposition of [Rh(
c
-Pic)
4
Cl
2
]MnO
4
salt at room tempera-
[8] G. Nolze, W. Kraus, Powder Diffr. 13 (1998) 256.
9] B. Ravel, M. Newville, J. Synchrotron Rad. 12 (2005) 537.
10] M. Newville, J. Synchrotron Rad. 8 (2001) 322.
11] K.-W. Nam, M.G. Kim, K.-B. Kim, J. Phys. Chem. C 111 (2007) 749.
[12] K. Nakamoto, IR Spectra of Inorganic and Coordination Compounds, fifth ed.,
Wiley, New York, 1997. p. 400.
13] D.C. Koningsberger, R. Prins, X-ray Absorption: Principles, Applications,
Techniques of EXAFS, SEXAFS, and XANES, in Chemical Analysis, John Wiley
and Sons, 1988. p. 688.
[
ture has been shown to result in formation of a mixture of MnO
nanoparticles and [Rh( -Pic) Cl ]OH complex. Thermal decompo-
sition of the mentioned mixture yields bimetallic particles
3–8 nm) of Rh Mn1ꢀx solid solution. Using of metal–organic
2
[
[
c
4
2
(
x
[
compounds as a precursor for preparation metal and oxide parti-
cles is a very popular topic today [15].
It is interesting to notice that after initial decomposition of the
[14] (a) S.V. Pol, V.G. Pol, G. Seisenbaeva, V.G. Kessler, A. Gedanken, Chem. Mater.
6 (2004) 1793;
b) S. Liu, J. Zhu, Y. Mastrai, I. Felner, A. Gedanken, Chem. Mater. 12 (2000)
205.
[15] O.A. Nikonova, K. Jansson, V.G. Kessler, M. Sunberg, A.I. Baranov, A.V.
Shevelkov, D.V. Drobot, G.A. Seisenbaeva, Inorg. Chem. 47 (2008) 1295.
1
(
2
salt Mn and Rh atoms are isolated in two different phases MnO
and [Rh( -Pic) Cl ]OH, respectively. During heating of this mixture
the metals form the phase of Rh Mn1ꢀx solid solution without
2
c
4
2
x
melting of components. Metal and oxide particles formed in
the decomposition process apparently have extra free energy. This