Electrochemical synthesis of complex compounds of transition elements with carboxyl- and carbonyl-containing ligands

Article abstract of DOI:10.1007/s11167-005-0416-7

Complex compounds of d- and f-elements with carboxyl- and carbonyl-containing ligands were synthesized by the electrochemical method. The influence exerted by a number of factors on the process course was studied. The dependence of the electrosynthesis parameters on the composition of the forming compounds was established. The composition of these compounds was determined. A new method for anodic synthesis of these compounds was developed.

Full text of DOI:10.1007/s11167-005-0416-7

Russian Journal of Applied Chemistry, Vol. 78, No. 6, 2005, pp. 897 902. Translated from Zhurnal Prikladnoi Khimii, Vol. 78, No. 6, 2005,
pp. 918 923.
Original Russian Text Copyright
2005 by Frolov, Bolotin, Panyshkin.
APPLIED ELECTROCHEMISTRY
AND CORROSION PROTECTION OF METALS
Electrochemical Synthesis of Complex Compounds
of Transition Elements with Carboxyl-
and Carbonyl-containing Ligands
V. Yu. Frolov, S. N. Bolotin, and V. T. Panyshkin
Kuban State University, Krasnodar, Russia
Received February 25, 2004
Abstract Complex compounds of d- and f-elements with carboxyl- and carbonyl-containing ligands were
synthesized by the electrochemical method. The influence exerted by a number of factors on the process
course was studied. The dependence of the electrosynthesis parameters on the composition of the forming
compounds was established. The composition of these compounds was determined. A new method for anodic
synthesis of these compounds was developed.
The electrochemical method simplifies synthesis
of known compounds [1 5] and makes it possible to
synthesize compounds that cannot be obtained other-
wise [6]. Moreover, the advantage of the anodic syn-
thesis is in that the process can be controlled and per-
formed in mild conditions with a high yield and purity
of the final products [7].
ditions (ligand concentration, temperature, solvent,
and electrode potential), and also to compare the prop-
erties of compounds synthesized by electrochemical
methods with those produced by chemical methods.
Acetylacetonates of rare-earth elements (REE) were
synthesized to confirm the suggestion that substances
exhibiting a tendency toward sublimation, which could
not be synthesized previously by other methods [19,
20], can be obtained by electrochemical synthesis.
Despite that the electrosynthesis is one of the oldest
methods for synthesis of coordination compounds [8],
the analysis of the anodic synthesis methods in
[1 7, 9 13] shows that many problems concerning
the theory and practical application of the method
have not been studied.
EXPERIMENTAL
The installation for anodic synthesis (Fig. 1) com-
prised a three-electrode cell, PI-50-1 potentiostat,
Transition-metal carboxylates of composition
M(O2CR)n (M = Cr; R = C2H5 or C6H5; n = 3; M =
Mn, Fe, or Ni; R = CH3, C2H5, C6H5, or n-C7H15;
n = 2) have been prepared [14] by electrochemical
oxidation of the corresponding metals in solutions of
carboxylic acids RCOOH in acetonitrile. In [15 17],
monocarboxylic acids containing one to four atoms
in the carbon chain were successfully used to syn-
thesize M(O2CR)2 salts. Oxalate complexes of iron
and copper were synthesized by the electrochemical
method in [18]. On the whole, publications devoted to
carboxylate complexes are scarce and analyze a rather
small number of the ligands.
The goal of this study was to develop new original
methods that would enable application of the electro-
chemical synthesis in a wider range and to a larger
number of objects and make it possible to perform di-
rected syntheses in which the composition of the form-
ing products is controlled by varying the process con-
Fig. 1. Schematic of a three-electrode cell for electrochem-
ical anodic synthesis (1) Thermostating jacket, (2) stirrer,
(3) outlet, (4) inlet, (5) separator, (6) working electrode,
(7) auxiliary electrode, and (8) reference electrode.
1070-4272/05/7806-0897 2005 Pleiades Publishing, Inc.

898
FROLOV et al.
Complex compounds obtained by electrochemical synthesis
Ligand
concen-
tration,
102, M
Supporting
electrolyte
and
Anode
An- Cath- poten-
Current den-
sity, A dm
Cur-
rent
efficien-
cy, %
2
Com-
pound
T,
C
Formula
ode
ode
tial,
V
c
solvent
anode cathode
I
II
III
IV
V
VI
VII
VIII
IX
CuSuc 5H2O
CuSuc 5H2O
CuSuc 5H2O
ZnSuc 2H2O
ZnSuc 2H2O
Cu(ButOH)2 2H2O
Cu(ButOH)2 2H2O
Ni(ButOH)2 2H2O
CuLac2 5H2O
CuLac2
ZnLac2 2H2O
CuMal 5H2O
CuMal
ZnMal 2H2O
CuHCit 5H2O
CuHCit
ZnHCit 2H2O
CuArg2 5H2O
ZnArg2 2H2O
NiArg2 3H2O
CuVal2 5H2O
ZnVal2 2H2O
NiVal2 3H2O
CuMet2 5H2O
ZnMet2 2H2O
NiMet2 3H2O
NdLac3 6DMF
10
10
10
10
10
0.5
0.5
5
H2O
H2O
Cu
Cu
Cu
Cu
Cu
Zn
Zn
Cu
Cu
Ni
0.5
0.5
0.05
0.8
0.8
0.5
0.5
0.5
5
5
5
5
5
5
5
5
5
5
25
60
25
25
60
25
60
60
25
85.3
80.6
53.2
98.6
99
78.7
81.5
83.2
98.5
H2O alcohol Cu
H2O
H2O
Zn
Zn
Cu
Cu
Ni
Cu
Cu
Zn
Cu
H2O
5 10
5 10
5 10
10 50
5 10
5 10
5 10
10 30
H2O
H2O
5 10
H2O
Cu 0.5 1
X
XI
XII
LiCl, HLac
H2O
Cu
Zn
Cu
Cu
Zn
1 1.5 0.1 0.2 0.1 0.2 25 80 64.2
0.8
0.3
1 1.5 0.1 0.2 0.1 0.2 135
0.8
0.5
1
5 10
10 20
5 10
10 20
60
25
87.8
97.6
45.9
80.3
96.4
35.6
87.8
89.6
81.5
78.9
95.3
76.8
56.8
92.7
85.2
65.4
H2O
XIII
XIV
XV
XVI
XVII
XVIII
XIX
XX
XXI
XXII
XXIII
XXIV
XXV
XXVI
XXVII
XXVIII TbLac3 8DMF
XXIX
XXX
XXXI
XXXII
XXXIII NdLac3
LiCl, H2Mal Cu
1
0.5 1
LiCl,
1
5 10
0.5 1
0.5
5
1
0.5
10
1
50
50
50
50
50
50
50
50
50
H2O
H2O
Zn
Cu
Cu
Zn
Cu
Zn
Ni
Cu
Zn
Ni
Cu
Zn
Ni
Nd
Tb
Gd
Nd
Tb
Er
5 8
10 15
10 20
25
25
Cu 0.3 0.5 10 15
Cu
Zn
H3Cit
1 1.5 0.1 0.2 0.1 0.2 165
0.8
H2O
3 10
10 15
10 20
10 20
5
10 20
15 20
5 15
10 25
5 15
1 5
1 5
1 5
1 5
1 5
1 5
1 5
1 5
1 5
1 5
1 5
1 5
1 5
25
25
25
25
25
25
25
25
25
25
25
25
25
25
25
25
25
25
25
25
25
25
25
25
H2O
Cu 0.15 0.3 10 15
H2O
Zn
Ni
Cu
Zn
Ni
Cu
Zn
Ni
Pt
Pt
Pt
Pt
Pt
Pt
Pt
Pt
Pt
Pt
Pt
Pt
Pt
0.5
0.5
0.25
0.25
0.5
0.3
0.25
0.8
5 8
1 5
10 15
10 15
3 5
5 15
5 10
1 3
1 3
1 3
1 5
1 5
1 3
1 5
1 3
1 3
1 5
1 5
1 3
1 5
H2O
H2O
H2O
H2O
H2O
H2O
H2O
LiCl, DMF
LiCl, DMF
LiCl, DMF
LiCl, DMF
LiCl, DMF
LiCl, DMF
LiCl, Acn
LiCl, Acn
LiCl, Acn
LiCl, Acn
LiCl, Acn
LiCl, Acn
LiCl, Acn
LiCl, Acn
0.5
0.3 0.5
0.3 0.5
0.5
0.5
0.5
GdLac3 8MDF
Nd2Mal3 6MDF
Tb2Mal3 8DMF
Er2Mal3 10MDF
Nd
Tb
Gd
Nd
Tb
Er
0.5
XXXIV
XXXV
XXXVI
XXXVII Tb2Mal3
XXXVIII Er2Mal3
TbLac3
GdLac3
Nd2Mal3
0.3 0.5
0.3 0.5
0.5
0.5
0.5
0.5
0.5
50
50
50
50
50
50
XXXIX
XL
NdAcac3
TbAcac3
Nd
Tb
10 15
10 15
10 15
10 15
Pt
PR-8 programmer, copper coulometer, instruments for
external monitoring of the current and voltage (poten-
tial), magnetic or mechanic stirrer, and thermostat.
erence. In nonaqueous solvents, an electrolytic bridge
was also used to prevent contamination of the solvent
with water.
The working electrode was made of the metal sub-
jected to anodic dissolution. Auxiliary electrodes
were made of inert materials or of the same materials
as working electrodes, depending on the objective.
A standard silver chloride electrode served as a ref-
The cell includes a thermostated jacket for per-
forming syntheses at elevated temperatures. In ad-
dition, the cathodic and the anodic compartments of
the cell are separated with a porous glass separator.
The electrochemical measurements can be performed
RUSSIAN JOURNAL OF APPLIED CHEMISTRY Vol. 78 No. 6 2005

ELECTROCHEMICAL SYNTHESIS OF COMPLEX COMPOUNDS OF TRANSITION ELEMENTS 899
using a magnetic stirrer. The PR-8 programmer makes
it possible to apply to the potentiostat a potential that
can be varied by an arbitrary program, including linear
or stepwise parts. The circuit includes a copper coulo-
meter for determining the current efficiency.
trolytes, is compensated for by the absence of foreign
ions in the solution, and, consequently, by the forma-
tion of simpler complex compounds. The ions formed
upon dissociation migrate toward the electrodes and
enter into the electrode reactions [4, 12].
The table lists the conditions in which complex
compounds of zinc, copper, nickel, and a number
of REEs (Nd, Tb, Pr, Gd, Er) with lactic (HLac),
malic (H2Mal), citric (H3Cit), succinic (H2Suc), and
-oxybutyric (HButOH) acids, arginine (HArg), va-
line (HVal), methionine (HMet), and acetylacetone
(HAcac) were synthesized. The presence of the com-
pounds as individual phase was confirmed by elemen-
tal and thermogravimetric (TG) analyses and by IR
spectroscopy.
C: 2H+ + 2e
H2 (HnL + ne
Ln + n/2H2),
A: mLn + nM
(nm)e
MnLm.
In the electrochemical systems Cu/HLac, Cu/H2Mal,
and Cu/H3Cit, the synthesis was performed using a liq-
uid (molten) ligand as a solvent. The working tem-
perature of the synthesis (see table) was higher than
the melting point of the ligand and lower than its de-
composition point. Inorganic chlorides were added to
the molten ligand, and the supporting electrolyte was
formed directly by the reaction
The content of metals was determined by com-
plexometric titration [21] and that of carbon, hydro-
gen, and nitrogen, by elemental gas-volumetric anal-
ysis.
nLiCl + HnL
LinL + nHCl .
The IR spectra were measured on a Perkin Elmer
180 spectrophotometer in the range 4000 400 cm
The synthesis in a liquid ligand was performed
with a preliminary dehydration of the ligands to a wa-
ter content of 1 10 mmol l . The compounds ob-
1
in a Vaseline oil suspension. The IR spectra of the car-
boxylic acid compounds synthesized were mainly an-
alyzed for the position of the absorption bands asso-
ciated with the carboxylic group and carboxylate ion,
which is consistent for the compounds studied with
published data [20, 22 25] for compounds with sim-
ilar structure and composition.
1
tained contained a large amount of water, but their
degree of hydration was considerably lower than that
for compounds obtained from solution and subjected
to dehydration. Therefore, the synthesis in a melt
can be recommended for obtaining substances with
the minimum content of water or compounds hardly
hydrated by the conventional methods. However,
the process rate is low in this case.
The thermogravimetric curves were measured at
20 1000 C on an MOM derivatograph (Hungary).
We used platinum crucibles, a platinum platinum-
rhodium thermocouple, and aluminum oxide as refer-
ence. The weighed portions were 50 mg, and the heat-
To choose the optimal range of ligand concentra-
tions for the anodic synthesis, we studied how the
potential of the metal electrodes varies with the li-
gand concentration in the solution at a constant ionic
strength (1 M LiCl).
1
ing rate, 10 deg min . As objects of analysis of
the thermogravimetric data served DTA, DTG, and
TG curves. In those cases when the composition of
the final phase formed by the thermolysis can be pre-
dicted rather reliably (e.g., formation of CuO as the
final product for complex copper compounds), we
performed a quantitative analysis for the content of
the ligand. The results of such an analysis were al-
ways in an agreement with the data obtained by chem-
ical analysis.
The dependences of the electrode potentials on the
ligand concentration in solution are shown in Fig. 2
for three typical systems. For the system constituted
by copper and amino acid (curves 1), extrema are
observed in the ligand concentration range studied
(0.005 M). In those cases when a complex compound
has a low stability constant, the equilibrium potential
of the electrode is mainly determined by the concen-
tration of the metal aqua complexes. If the complex
compound forms a sparingly soluble phase on the elec-
trode surface and(or) a very stable complex compound
is formed, then the electrode potential is also de-
pendent on the concentration of the anionic form of
the ligand in solution. This predetermines the com-
plicated character of the dependences presented.
The synthesis was performed in water and in non-
aqueous solvents: acetonitrile (Acn) and dimethyl-
formamide (DMF). In aqueous solutions, the synthe-
sis was carried out without a supporting electrolyte,
with the electric conduction provided by ions formed
upon the dissociation of the ligands (H+, Ln ).
The decrease in the electrical conductivity, which is
due to the fact that these substances are weak elec-
RUSSIAN JOURNAL OF APPLIED CHEMISTRY Vol. 78 No. 6 2005

900
FROLOV et al.
Fig. 2. Potential E of (1) copper, (2) nickel, and (3) zinc vs. the concentration c of (a) malic acid, (b) valine, and (c) arginine.
At low concentrations of the ligand (0.005 M and
less), the electrode is frequently passivated. In the ab-
sence of a supporting electrolyte, such concentrations
also lead to a low electrical conductivity of the solu-
tion. In these cases, it is suggested to perform elec-
trolysis at high ligand concentrations by gradually rais-
ing the content of a ligand to the maximum possible
value at a given temperature. For the amino acid sys-
tems, this means that the concentration can be raised
from 0.005 M to the point of saturation (Fig. 2). It
was found that such a procedure frequently makes it
possible to avoid passivation of copper and zinc elec-
trodes.
The electrosynthesis of the complex nickel com-
pounds with hydroxy acids (except -hydroxy butyric
acid) poses certain difficulties. When the electrode
potentials are low (1 2 V), the electrode in the system
chosen is passivated, the electrolysis proceeds very
slowly, and the anodic products cannot be identified
by analysis as individual compounds. At high anode
potentials (up to 3 V), oxygen evolution from water
proceeds at the anode, which makes the nickel elec-
trode completely inert. The successful synthesis of
the nickel(II) complex with -hydroxy butyric acid
is probably favored by the fact that it is synthesized
from the preligand (2-butenolide), the true concentra-
tion of the ligand near the anode surface is very low,
and its loss is continuously compensated for by hy-
drolysis of 2-butenolide directly at the anode sur-
face:
Copper easily dissolves in all the systems studied,
with a high current efficiency at small shifts of the po-
tential from the equilibrium value and high dissolu-
tion current densities.
OH
HO
Zinc dissolves well in the system with a stronger
polarization, at higher anode potentials and lower cur-
rent densities. Hydrogen is evolved at the cathode at
the beginning of the process. Then, as metal ions are
accumulated in the electrolyte, a parallel process of
zinc separation commences, which decreases the cur-
rent efficiency of the anodic process. The metal ions
are discharged at the cathode to form dendrites, which
are accumulated on the cell bottom because of the poor
adherence to the electrode, thus creating additional
difficulties in isolation of the final product. This dif-
ficulty is eliminated if a cell with separated electrode
compartments is used. In all probability, the high cur-
rent efficiencies by the zinc compounds are due to
the simultaneous spontaneous dissolution of the zinc
electrodes:
+ H2O
O
O
O
It was established for copper in an analogous sys-
tem that copper compounds with different states de-
grees oxidation are formed by electrochemical syn-
thesis at different temperatures: a pale green copper(II)
complex insoluble in water (compound VI) is formed
at 25 C, and a copper(I) complex insoluble in water
(compound VII), at 65 C.
Comparison of the IR spectra of the compounds
obtained in the REE(Nd, Tb)/HAcac system, which
have, according to the results of an analysis, the com-
position LnAcac3, with the spectrum of the pure li-
gand (shift of the carbonyl vibrational band at around
1
1
1650 cm by 50 60 cm ) shows that a chemical
carbonyl bond is formed [22]. The thermogravimetric
Zn + 2HL
ZnL2 + H2 .
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ELECTROCHEMICAL SYNTHESIS OF COMPLEX COMPOUNDS OF TRANSITION ELEMENTS 901
Fig. 3. Thermograms of (a) neodymium and (b) terbium trisacetylacetonates. (T) Temperature, ( m) relative loss of mass,
and ( ) time.
data in Fig. 3 suggest that the substances synthesized
are volatile: a drastic mass loss (96%) observed at
T = 310 C for compound (XXXIX) corresponds to
a strong exothermic effect, which may be due to sub-
limation of a sample and its simultaneous combustion
in the vapor state; for compound (XL), a 75%-loss
of mass, accompanied by a pronounced endothermic
effect, is observed at T = 220 C. Thus, the electro-
chemical synthesis of acetylacetonates of rare-earth
elements is a simpler and less expensive method, and,
which is the most important, it gives anhydrous com-
pounds with a molecular crystal lattice [26].
Various nonaqueous solvents also differently affect
the composition of the products obtained and the pro-
cess efficiency. Use of aqueous-alcoholic media in
synthesis of d-element succinates was ineffective.
It was found for aprotic solvents that there is a rela-
tionship between the solvent chosen and formation
of solvated complexes. The formation of solvates
(solvation) depends on the relative donor strength
of the solvent and the ligand used and on the tem-
perature mode of electrolysis. For example, solvated
complexes are always formed in dimethylformamide,
whereas in acetonitrile, this occurred only in several
cases. It may be concluded that acetonitrile is the most
suitable solvent for synthesis of unsolvated com-
pounds.
In the course of synthesis in a system containing
copper electrodes and an aqueous solution of lactic
acid at high anode potentials (2 3 V), a finely dis-
persed colorless water-insoluble solid substance is
formed at the anode alongside with a compound
CuLac2 5H2O, which is obtained in a very low yield
(5 10%). An analysis of the compound obtained re-
vealed neutral anhydrous copper carbonate CuCO3.
Therefore, it was suggested that the electrochemical
anodic reaction of decarboxylation of lactic acid
(Kolbe reaction) occurs in such a synthesis as a side
process unknown previously for -substituted hy-
droxy carboxylic acids and their salts. The process
can be used to introduce into the anodic Kolbe syn-
thesis new classes of organic substances, which is
important for practice.
The electrochemical synthesis has a high efficien-
cy: the yield of substance and the current efficiency
(>50%) are considerably higher than those in the con-
ventional chemical syntheses. In addition, the electro-
chemical synthesis is a single-stage process, which
also makes higher the yield of the product. In the gen-
eral case, the yield of substance and the current ef-
ficiency may be different or may coincide.
The effect of the process temperature on the com-
position of the products obtained was especially strong
in interaction of copper with 2-butenolide, when at
a comparatively small temperature difference, two
products of different compositions were formed, with
RUSSIAN JOURNAL OF APPLIED CHEMISTRY Vol. 78 No. 6 2005

902
FROLOV et al.
copper in different oxidation states. In other cases,
differently solvated compounds were formed.
11. Garnovskii, A.D., Ryabukhin, Yu.I., and Kuzha-
rov, A.S., Koord. Khim., 1984, vol. 10, no. 8,
p. 1011 1033.
12. Kukushkin, V.Yu. and Kukushkin, Yu.N., Teoriya i
praktika sinteza koordinatsionnykh soedinenii (The-
ory and Practice of Synthesis of Coordination Com-
pounds), Leningrad: Nauka, 1990.
13. Tomilov, A.P., Chernykh, I.N., and Kargin, Yu.N.,
Elektrokhimiya elementoorganicheskikh soedinenii:
Elementy I, II i III grupp periodicheskoi sistemy i
perekhodnye elementy (Electrochemistry of Hetero-
Organic Compounds: Elements of Groups I, II, and
III of the Periodic System and Transition Elements),
Moscow: Nauka, 1985.
14. Kumar, N., Tuck, D.G., and Watson, K.D., Canad.
J. Chem., 1987, vol. 65, no. 6, p. 740.
15. Banait, J.S., and Pahil, P.K., Polyhedron, 1985, vol. 4,
no. 6, p. 1031.
16. Banait, J.S., and Pahil, P.K., Bull. Electrochem., 1989,
CONCLUSIONS
(1) The optimal concentration ranges of the ligand
for electrochemical synthesis of complex compounds,
temperature, solvent, and gaseous medium of synthe-
sis were determined on the basis of potenstiostatic
data.
(2) Anodes made of rare-earth metals were used
in electrochemical synthesis for the first time. Thermo-
gravimetric data demonstrated that the physical prop-
erties (high volatility) and structure of acetylacetonates
of rare-earth elements synthesized by this method in
anhydrous acetonitrile differ from the properties of
the previously synthesized analogues.
(3) It was shown that the anodic dissolution of
the metal facilitates decarboxylation of hydroxy acid.
vol. 5, no. 2, p. 264.
17. Bott, R., Healy, P.C., and Sagatys, D.S., Chem.
Commun., 1998, no. 21, p. 2403.
18. Kumar, N, and Tuck, D.G., Canad. J. Chem., 1984,
REFERENCES
vol. 62, no. 14, p. 1701.
19. Przystal, J.K., Bos, W.G., and Liss, I.B., J. Inorg.
Nucl. Chem., 1971, vol. 33, no. 5, p. 679.
20. Panyushkin, V.T., Spektroskopiya koordinatsionnykh
soedinenii redkozemel’nykh elementov (Spectroscopy
of Coordination Compounds of Rare-Earth Elements),
Rostov-on-Don: Rostov. Univ., 1984.
21. Schwarzenbach, G. and Flaschka, H., Complexometric
Titrations, London: Methuen, 1969, 2nd ed.
1. Habeeb, J.J., Tuck, D.G., and Walters, F.H., Coord.
Chem., 1978, vol. 8, no. 1, p. 27 33.
2. Habeeb, J.J., Nielson, L., and Tuck, D.G., Inorg.
Chem., 1978, vol. 17, no. 3, p. 306 310.
3. Habeeb, J.J., and Tuck, D.G., J. Chem. Soc. Chem.
Commun., 1975, vol. 5, no. 7, p. 808 809.
4. Konev, V.A., Kukushkin, V.Yu., and Kukush-
kin, Yu.N., Zh. Neorg. Khim., 1986, vol. 31, no.7,
p. 838 843.
22. Nakamoto, K., Infrared and Raman Spectra of Inor-
ganic and Coordination Compounds, New York:
Wiley, 1978, 3rd ed.
23. Ablov, A.V., Proskina, N.I., and Gapurina, P.F., Ko-
lebatel’nye spektry v organicheskoi khimii (Vibra-
tional Spectra in Organic Chemistry), Moscow: Nau-
ka, 1971.
5. Laube, B.L. and Schmulbach, C.D., Prog. Inorg.
Chem., 1971, vol. 14, no. 1, p. 65 181.
6. Chakravorti, M.C. and Subrahmanyam, G.V.B.,
Coord. Chem. Rev., 1994, vol. 135, no. 1, pp. 65 92.
7. Garnovskii, A.D., Kharisov, A.I., Gokhon-Zorilla, G.,
and Garnovskii, D.A., Usp. Khim., 1995, vol. 64,
no. 3, p. 251 236.
24. Bol’shakov, G.F., Glebovskaya, E.A., and Kap-
lan, Z.G., Infrakrasnye spektry i rentgenogrammy
geteroorganicheskikh soedinenii (Infrared Spectra
and X-Ray Diffraction Patterns of Hetero-organic
Compounds), Leningrad: Khimiya, 1967.
25. Bellamy, L.J., The Infrared Spectra of Complex Mol-
ecules, New York: Wiley, 1975.
26. RF Patent 2191190.
8. Zamyatkina, V.M., Kukushkin, Yu.N., and Makare-
nya, L.A., Lev Aleksandrovich Chugaev, Moscow:
Nauka, 1973.
9. Tuck, D.G., Pure Appl. Chem., 1979, vol. 51, no. 2,
p. 2005.
10. Bogdashev, N.N., Garnovskii, A.D., Osipov, O.A.,
et al., Zh. Obshch. Khim., 1976, vol. 46, no. 3,
p. 675 680.
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