Reaction of [Pt(NH3)4]Cl2?H 2O and NH4ReO4 in alkaline aqueous solution at 190°C (under pressure)

Article abstract of DOI:10.1134/S1070363208110017

Reactions of thermolysis under pressure of tetraammineplatinum(II) chloride and ammonium perrhenate in alkaline aqueous solution were studied. The products formed at the thermolysis in a pressure reactor were investigated. A model of platinum and rhenium ions reduction to metallic state by inner sphere ammonia from [Pt(NH₃)₄]Cl₂ is suggested.

Full text of DOI:10.1134/S1070363208110017

ISSN 1070-3632, Russian Journal of General Chemistry, 2008, Vol. 78, No. 11, pp. 1997–1999. © Pleiades Publishing, Ltd., 2008.
Original Russian Text © V.I. Zarazhevskii, V.V. Grebnev, E.F. Fesik, G.D. Mal’chikov, 2008, published in Zhurnal Obshchei Khimii, 2008, Vol. 78, No. 11,
pp. 1761–1763.
Reaction of [Pt(NH ) ]Cl ·Н О and NH ReO
3
4
2
2
4
4
in Alkaline Aqueous Solution at 190°С (under Pressure)
V. I. Zarazhevskii, V. V. Grebnev, E. F. Fesik, and G. D. Mal’chikov
Korolev Samara State Aerocosmic University,
Moskovskoe sh. 34, Samara, 443086 Russia
e-mail: malchikow.chem@mail.ru
Received May 6, 2008
Abstract—Reactions of thermolysis under pressure of tetraammineplatinum(II) chloride and ammonium
perrhenate in alkaline aqueous solution were studied. The products formed at the thermolysis in a pressure
reactor were investigated. A model of platinum and rhenium ions reduction to metallic state by inner sphere
3 4 2
ammonia from [Pt(NH ) ]Cl is suggested.
DOI: 10.1134/S1070363208110017
The results obtained in the chemical reactions of
ammonium–chloride complexes of noble metals in
aqueous alkaline solution at elevated temperature
presumed that by analogy with the reaction (1) the
ammonia “in statu nascendi” as well as Pt can behave
as reducing agents for rhenium.
2
+
(
above 100°С) gave rise to development of the method
of thermolysis under pressure of metallic systems
powders, sols, coatings on various materials) that
The results listed in Table 1 show that the solid
product contains two phases, metallic platinum and
rhenium.
(
found application, e.g., for producing catalysts [1–4].
The established fact of formation of platinum and
rhenium in metallic state at the reaction of [Pt(NH ) ]Cl ·
The method is based on the irreversible reduction
of the complexing metal ion by the inner sphere
ammonia with liberation of the metal [5].
3
4
2
Н О and NH ReO allows to suggest the following
2
4
4
equation for this reaction:
2
–i
–
[
М(NH
3
)
4–iCl
i
]
+ 2OH
0
0
3
[Pt(NH
3
)
4
]Cl
8N
2
+ 6NH
↑ + 2NH
4
ReO
4
+ 6KOH → 3Pt + 6Re
O. (2)
0
–
→
М + 1/3N + (10/3-i)NH
2
3
+ iCl + 2H
2
O,
(1)
+
2
3
↑ + 6KCl + 30H
2
М = Pt, Pd, Rh, Ir, Ru, Co, Ni, Cu, and others.
To prove the stoichiometry of this reaction we
carried out experiments on quantitative determination
of liberated ammonia. The results of typical experi-
ments are listed in Table 2.
Heating of solid ammonia compounds also leads to
formation of metal as a result of solid phase
thermolysis [6, 7]. Thus certain analogy can be traced
between the processes of autoclave and solid phase
thermolysis of ammonia complexes. The products of
autoclave thermolysis of the complex ammoniates
containing different metals are polymetallic solid
precipitates. A series of investigations [8, 9] has been
carried out on solid phase thermal transformations of
double salts with complex cations and anions
containing different metals, and the corresponding
metallic phases were obtained.
The experiments 1–4 were carried out at an excess
of tetraammineplatinum(II) chloride with respect to the
calculation accounting for stoichiometry in keeping
with Eq. (2). For these experiments the theoretical
amount of free amminia was calculated as a sum of
two values: that based on Eq. (2) assuming a complete
consumption of rhenium salt, and based on Eq. (1)
corresponding to the consumption of excess tetra-
ammineplatinum(II). In exp. no. 5 the ratio of platinum
and rhenium was taken according to the stoiciometry
of Eq. (2). The data in Table 2 show good consistence
of experimental values and theoretical amounts of free
In this work we present results of the study of
reaction of [Pt(NH ) ]Cl ·Н О with NH ReO in
3
4
2
2
4
4
alkaline medium at heating in autoclave at 190°С. We
1997

1
998
ZARAZHEVSKII et al.
Table 1. X-ray characteristics of platinum and rhenium
Product of autoclave thermolysis, phase Pt
Product of autoclave thermolysis, phase Re
I, %
d/n, Å (exp) d/n, Å (ASTM)
2θ, deg
2θ, deg
I, %
d/n, Å (exp)
d/n, Å (ASTM)
5
0.7
100
–
2.261
–
2.27
–
47.4
51.5
54.7
56.5
67.8
82.1
30
30
2.408
2.228
2.107
1.254
–
2.388
2.226
2.105
1.626
1.380
1.173
–
5
8
9.3
8.8
85
84
100
60
1.957
1.383
1.180
1.130
1.956
1.385
1.179
1.130
100
11
1
1
10.2
17.8
22
20
–
3
Table 2. Results of determination of NH content in the solutions after autoclave experiments (150 min, 190°С)
Sample weight, g
4 4
·Н NH ReO
m NH
3
,
3
m NH ,
Run no.
% of theoretical value
(
theor), g
0.101
0.101
0.033
0.033
0.025
(exp), g
0.0969
0.0942
0.0270
0.0275
0.0241
[
Pt(NH
3
)
4
]Cl
2
2
О
1
2
3
4
5
1.036 (0.55 Pt)
1.036 (0.55 Pt)
0.342 (0.189 Pt)
0.342 (0.189 Pt)
0.776 (0.43 Pt)
0.789 (0.55 Re)
0.789 (0.55 Re)
0.260 (0.181 Re)
0.260 (0.181 Re)
1.181 (0.82 Re)
95.9
93.3
81.2
83.3
96.0
ammonia. Thus, reaction of salts in autoclave
conditions proceeds according to Eq. (2).
measured by the method of acid-base titration along
the procedure in [11]. Analysis was carried out
according to following sequence. The autoclave with
frozen at –15°C solution was placed to a tubular
furnace equipped with reflux microcondenser and
receiver containing 0.1 N solution of hydrochloric
acid. The autoclave was heated to 130–150°С, and
ammonia was distilled off. The distillation was stopped
when 2/3 by volume of liquid was passed to the
receiver containing acid. The acid excess was titrated
with potassium hydroxide solution (0.1 N) against
methyl orange indicator. The mass of free ammonia in
the system was calculated from the results of titration,
and it was compared with the theoretical amount of
ammonia calculated from the assumed reaction
equation. Close theoretical and experimental mass
values point to the reliability of the assumed stoi-
chiometry of reaction of platinum and rhenium salts.
The results of this work allow obtaining bimetallic
platinum–rhenium systems without further reduction
operations, e.g., by hydrogen, at the production of
platinum–rhenium catalysts.
EXPERIMENTAL
In the work was used tetraammineplatinum(II)
dichloride synthesized along the procedure in [10],
commercial ammonium perrhenate, and KОН of
“
chemically pure” grade.
The experiments were carried out in fluoroplastic
autoclaves by the procedures described in [1–7]. The
weighed samples of [Pt(NH ) ]Cl ·Н О and NH ReO
3
4
2
2
4
4
were added to a solution of potassium hydroxide of
required concentration, and the mixture was then
saturated with nitrogen to avoid side reactions with air
oxygen. The autoclave with alkaline solution of
mixture of [Pt(NH ) ]Cl ·Н О and NH ReO was
In the autoclave after opening a solid product of
grey color with metallic luster was found. It was
isolated from solution by filtration through a glass frit,
washed with distilled water, and dried. Phase
composition of the solid products obtained in the
autoclave process was examined by the method of X-
ray phase analysis (XRPA) on a DRON-2.0 diffrac-
tometer (FeK -radiation, λ 1.937 Å, U 20 kV, I 20 mA,
3
4
2
2
4
4
sealed and kept at temperature 190°С for 150 min with
stirring. After that the autoclave was rapidly cooled to
room temperature, and the solution within was frozen
for minimization of loss of free ammonia by the
system. The content of ammonia after reactions was
α
α
α
α
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 78 No. 11 2008

REACTION OF [Pt(NH
3
)
4 2
]Cl ·Н
2
О AND NH
4
ReO
4
1999
–
1
2
deg min ). Decoding of the diffractograms was
6. Fesik, E.V., Grebnev, V.V., and Mal’chikov, G.D.,
Vestnik Samar. Gos. Univ., Ser. Estestv. nauk, 2007,
no. 9/1(59), p. 287.
carried out using databases ASTM and from [12].
REFERENCES
7
. Mal’chikov, G.D. and Vershkov, A.V., Abstracts of
Papers, XVI All-Union Chernyaev Symposium on the
Chemistry, Analysis and Technology of Platinum Group
Metals, Krasnoyarsk, 1987, part 2, p. 448.
1
. Mal’chikov, G.D. and Vershkov, A.V., Abstracts of
Papers, XIII All-Union Chernyaev Symposium on the
Chemistry, Analysis and Technology of Platinum Group
Metals, Sverdlovsk, 1986, vol. 1, p. 208.
8
9
. Korenev, S.V., Venediktov, A.B., Shubin, Yu.V.,
Gromilov, S.A., and Yusenko, K.V., Zh. Struct. Khim.,
2
3
. Mal’chikov, G.D., Vershkov, A.V., Rogin, N.Ya.,
Chernikova, G.E., and Piganov, M.N., Abstracts of
Papers, XIV All-Union Chernyaev Symposium on the
Chemistry, Analysis and Technology of Platinum Group
Metals, Novosibirsk, 1989, vol. 2, p. 117.
2
006, vol. 44, no. 1, p. 58.
. Zadesenets, A.V., Khraeanko, S.P., Shubin, Yu.V.,
Baidina, I.A., and Korenev, S.V., Koord. Khim., 2006,
vol. 32, no. 5, p. 389.
1
0. Sintez kompleksnykh soedinenii metallov platinovoi
gruppy. Spravochnik (Synthesis of Coordination
Compounds of Platinum Group Metals. Handbook),
Chernyaev, I.I., Ed., Moscow: Nauka, 1964, p. 325.
. Mal’chikov, G.D., Timofeev, N.I., Rasshchepkina, N.A.,
Kamenskii, A.A., Ryzhikov, V.G., Tupikova, E.N., and
Tarasov, V.I., RF Patent 2063804, MPK V 01 J 23/89,
Byul. Izobret., 20.07.1996.
4
5
. Mal’chikov, G.D., Chernikova, G.E., Vershkov, A.V.,
Rogin, N.Ya., Kovalenko, N.L., and Orlov, A.M., USSR
Inventor’s Certificate no. 1420997.
11. Krasheninnikov, S.A., Kuznetsova, A.G., Saltano-
va, V.P., Surkov, E.I., and Yakhontova, E.L., Tekhni-
cheskii analiz i kontrol’ v proizvodstve neorganicheskikh
veshchestv (Technical Analysis and Inspection at the
. Mal’chikov, G.D., Timofeev, N.I., Bogdanov, V.I.,
Rasshchepkina, N.A., and Tupikova E.N., Proizvodstvo
Production of
Inorganic Substances), Moscow:
Vysshaya Shkola, 1968, p. 208.
i
ekspluatatsiya izdelii iz blagorodnykh metallov
(
Producing and Exploitation of Articles Made of Noble
12. Mirkin, L.I., Spravochnik po rentgenostrukturnomu
analizu polikristallov (Handbook on the X-Ray
Structural Analysis of Polycrystals), Moscow, 1961.
Metals), Yekaterinburg: Ural. Otd. Ross. Akad. Nauk,
997, p. 125.
1
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