PROPOSED COMPOSITION OF COMPLEXES AND ION ASSOCIATES IN CITRIC ACID SOLUTIONS CONTAINING NICKEL SULFAMATE AND POTASSIUM PERRHENATE(Review)
The article presents an analysis of the experimental data available in the scientific literature on the conditions for obtaining nickel-rhenium alloys, promising as cathodes for electrolytic hydrogen production. The problem of searching for additional evidence of the mutual influence and interaction...
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| Дата: | 2025 |
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| Автор: | |
| Формат: | Стаття |
| Мова: | Англійська |
| Опубліковано: |
V.I.Vernadsky Institute of General and Inorganic Chemistry
2025
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Ukrainian Chemistry Journal| _version_ | 1871466122691215360 |
|---|---|
| author | Maltseva, Tetiana |
| author_facet | Maltseva, Tetiana |
| author_institution_txt_mv | [
{
"author": "Tetiana Maltseva",
"institution": "V.I.Vernadsky Institute of General and Inorganic Chemistry of the National Academy of Sciences of Ukraine, 32\/34 Academic Palladin Avenue, Kyiv, 03142, Ukraine"
}
] |
| author_sort | Maltseva, Tetiana |
| baseUrl_str | https://ucj.org.ua/index.php/journal/oai |
| collection | OJS |
| datestamp_date | 2026-07-22T08:23:55Z |
| description | The article presents an analysis of the experimental data available in the scientific literature on the conditions for obtaining nickel-rhenium alloys, promising as cathodes for electrolytic hydrogen production. The problem of searching for additional evidence of the mutual influence and interaction of nickel (II), citrate and perrhenate ions in the deposition electrolyte is formulated. For this purpose pH-metric titration of solutions containing (1) citrate ions only; (2) citrate and nickel(II) ions; (3) citrate, nickel(II) and potassium perrhenate ions – was carried out in the pH range from 1.5 to 2.0. Simultaneous release of protons associated with both the reaction of nickel with citrate to form the corresponding NiHCit- complexes and the reaction of citrate with perrhenate to form the (ReO4∙H2Cit)2- complexes was shown. Since the total concentration of reacted protons in the solution with nickel (II) and perrhenate corresponds to the sum of the concentrations of nickel and perrhenate ions, this confirms that reaction of complexes of citrate/perrenate formation occurs simultaneously (in parallel) with the reaction of the formation of the nickel-citrate complexes. And further pH arising should lead to well-known formation of NiCit24- complexes, which can be associated with two ions of perrenate. Based on the analysis of date concerning the influence of the components of nickel-rhenium alloy deposition electrolytes on electrodeposition results, it was concluded that the predominant form providing the observed results concern both high current yield and high rhenium content in the alloy is an electrochemically inactive ion associate consisting of the NiCit24- complex and two perrhenate ions. Destroying in the near-cathode solution layer, it provides a periodic predominance of perrhenate ions, which can be restored without kinetic difficulties. The composition of complexes and ionic associates is proposed for a wide range of experimental data on the induced deposition of nickel-rhenium alloy coatings from citrate electrolytes, based on the quantitative ratios of the complex components in the electrolyte and the pH value. |
| doi_str_mv | 10.33609/2708-129X.91.4.2025.61-71 |
| first_indexed | 2025-09-24T17:44:00Z |
| format | Article |
| fulltext |
61
UDC 544.654.2+544.6.018+54.386 doi: 10.33609/2708-129X.91.4.2025.61-71
PROPOSED COMPOSITION OF COMPLEXES AND ION ASSOCIATES
IN CITRIC ACID SOLUTIONS CONTAINING NICKEL SULFAMATE
AND POTASSIUM PERRHENATE.
T.V. Maltseva
Vernadsky Institute of General and Inorganic Chemistry of the National Academy of Sciences of
Ukraine, Academician Palladin Ave., 32/34, Kyiv, 03142, Ukraine
∗e-mail: maltseva50tv@gmail.com
The article presents an analysis of the experimental data available in the scientific literature
on the conditions for obtaining nickel-rhenium alloys, promising as cathodes for electrolytic
hydrogen production. The problem of searching for additional evidence of the mutual influ-
ence and interaction of nickel (II), citrate and perrhenate ions in the deposition electrolyte
is formulated. For this purpose pH-metric titration of solutions containing (1) citrate ions
only; (2) citrate and nickel(II) ions; (3) citrate, nickel(II) and potassium perrhenate ions – was
carried out in the pH range from 1.5 to 2.0. Simultaneous release of protons associated with
both the reaction of nickel with citrate to form the corresponding NiHCit- complexes and the
reaction of citrate with perrhenate to form the (ReO4∙H2Cit)2- complexes was shown. Since
the total concentration of reacted protons in the solution with nickel (II) and perrhenate cor-
responds to the sum of the concentrations of nickel and perrhenate ions, this confirms that
reaction of complexes of citrate/perrenate formation occurs simultaneously (in parallel) with
the reaction of the formation of the nickel-citrate complexes. And further pH arising should
lead to well-known formation of NiCit2
4- complexes, which can be associated with two ions of
perrenate. Based on the analysis of date concerning the influence of the components of nickel-
rhenium alloy deposition electrolytes on electrodeposition results, it was concluded that the
predominant form providing the observed results concern both high current yield and high
rhenium content in the alloy is an electrochemically inactive ion associate consisting of the
NiCit2
4- complex and two perrhenate ions. Destroying in the near-cathode solution layer, it
provides a periodic predominance of perrhenate ions, which can be restored without kinetic
difficulties. The composition of complexes and ionic associates is proposed for a wide range
of experimental data on the induced deposition of nickel-rhenium alloy coatings from citrate
electrolytes, based on the quantitative ratios of the complex components in the electrolyte and
the pH value.
Key words: nickel-rhenium alloys, citrate complexes, ion interaction, pH-titration, elect
rolyte composition, calculations.
62 ISSN 2708-129X. Укр. хім. журн., 2025
PROPOSED COMPOSITION OF COMPLEXES AND ION ASSOCIATES IN CITRIC ACID SOLUTIONS
CONTAINING NICKEL SULFAMATE AND POTASSIUM PERRHENATE.PHISICAL CHEMISTRY
INTRUDUCTION. Many research groups
have shown a significant decrease in the over-
potential of the hydrogen evolution reaction
(HER) in an alkaline medium in comparison
with individual alloy components on iron-rhe-
nium subgroup metal alloys, and have con-
firmed the acceptable stability of the alloy pro
perties and their high corrosion resistance. In
2008, the authors of [1] reviewed the works on
the electrodeposition of rhenium and its alloys,
in which, among other things, it was noted that
the deposition mechanism of rhenium alloys is
a subject of discussion. A number of studies
since 2009 [2–7] have been aimed at studying
the electrodeposition and properties of nickel-
rhenium alloy coatings from citrate-contain-
ing electrolytes, as well as the proposed mecha-
nisms of metal co-deposition in the alloy. Most
of the electrolytes contained nickel sulfamate,
boric acid, citrate and perrhenate ions. Ad-
dition of sulfamate to galvanic baths results
in higher deposition rates, superior scatter-
ing ability, and reduced porosity and residual
stresses in the coating [8]. Citrate forms sta-
ble complexes with Ni, Co, and Fe, which has
a positive effect on the deposition of alloys of
these elements [9]. It was found that the alloy
composition is influenced by such key factors
as the ratio of concentrations of the three com-
ponents of the electrolyte (nickel, citrate, per-
rhenate ions), pH of the solution, temperature
and the applied value of the deposition current
density. It should be noted that with a ratio of
citrate and nickel ions of 1:1 (34 mmol/l), the
maximum achieved concentration of rhenium
in the alloy was 54.9 at. %, with a current effi-
ciency of no more than 60% [7]. At the same
time, a detailed study of the effect of the ratio
of the concentrations of the iron group metal
and citrate ions showed [4] that it is in this case
that the ratio of partial deposition currents
Ni/Re is maximum, and to increase the concent
ration of rhenium in the alloy, it is necessary
to increase the concentration of citrate ions in
the electrolyte. The question of the existence of
complexes of the putative composition ReO4
−/
(NiCit)− or ReO4
−/(NiCit)2
4− in such solutions
arose on the basis of data on the mutual influ-
ence of both the presence and the change in the
concentration of each of the deposited compo-
nents on the current efficiency and the com-
position of the resulting alloy. Based on the
results of these studies and some earlier ones,
it could be assumed that the simultaneous
electrodeposition of nickel and rhenium is due
to the interaction of ions of all three compo-
nents in the electrolyte: perrhenate, nickel and
citrate. The mechanism proposed in [2] was
based on a special type of chemical precipita-
tion in which the reducing agent is metallic Ni,
formed in situ. In [3], the probable mechanism
by which the addition of Ni, Fe or Co to the
solution increases the deposition rate of Re is a
unique type of chemical precipitation in which
the reducing agent is Me0, formed in situ. The
authors of the study [4] indicate that, based on
all the signs discovered, the electrodeposition
of the nickel-rhenium alloy should be recog-
nized as induced, by analogy with the depo-
sition of alloys of iron subgroup metals with
molybdenum and tungsten. Induced co-depo-
sition of rhenium from such rhenium-contain-
ing electrolytes proceeds without kinetic diffi-
culties. Coatings up to 25 microns thick were
obtained in 60 minutes of deposition with a
current efficiency of up to 95%, and the con-
centration of rhenium in the alloy can reach a
value greater than 90%. The assumption about
the interaction of perrhenate and citrate ions
with the formation of a reversible electroactive
63https://ucj.org.ua
T.V. Maltseva UCJ № 4 / Vol. 91
complex citrate/perrhenate (H2CitReO4)
2− was
previously put forward to explain the cata-
lytic effect of citrate ions on the reduction of
ReO4
− ions in electrolytes with medium acidity
(pH = 2–5), which was demonstrated by po-
larography [10]. However, the authors failed to
confirm the formation of such complexes by
spectrophotometry either in the visible or UV
spectrum. In later studies of the ternary system
«nickel-citrate-perrhenate», nickel complexes
with perrhenate ions were also not detected
[11]. At the same time, the alloy deposition in-
dices indicate the interaction of all three com-
ponents in the electrolyte. The authors of [11]
particularly emphasize the fact that the mani-
festation of the above phenomena requires the
simultaneous presence of the three compo-
nents in the electrolyte. And this fact leads to
the conclusion about the existence of a precur-
sor similar to that detected in the case of in-
duced co-precipitation of alloys with tungsten
[12–14]. But since in the case of a direct ana
logy it is necessary to assume the formation in
solution of a complex containing 9 perrhenate
molecules, which is impossible, on the basis
of the fundamental role of freshly deposited
nickel in the electroreduction of rhenium, dis-
covered in works [2–6], a catalytic mechanism
of alloy deposition was proposed according to
which Ni2+ ions are reduced and deposited first
and, as a strong reducing agent, promote the
reduction of 7-valent rhenium in perrhenate
ions to the 5-valent form in ReO3- ions. Thus,
the electrodeposition of the alloy is interpreted
as a catalytic process in which nickel plays the
role of a catalyst for the reduction of rhenium.
Its concentration should not change as a result
of the overall reaction. But since some amount
of nickel was detected in the part of the coating
consisting mainly of rhenium, it had to be sta
ted that the process is unique and the catalyst is
formed in situ as part of the reduction process.
In contrast to earlier studies [2–7], in which
the deposition time of alloy coatings was mi
nutes and hours, the initial stages of alloy depo-
sition were studied in [9] in order to better un-
derstand and confirm the catalytic mechanism
of deposition. In this work, the electrodeposi-
tion of Re-Ni alloys was studied at a deposi-
tion time of 0.05–60 s, and the authors found
rhenium current efficiency values significantly
exceeding 100%. The alloy current efficiency
and the rhenium content in the coating de-
creased with increasing alloy deposition time.
According to the authors, this nature of the
dependence of rhenium deposition on deposi-
tion time indicates the occurrence of a parallel
chemical reaction at the early stages of alloy
deposition, catalyzing the deposition of rheni-
um into the alloy. A sharp decrease in the rate of
this chemical reaction, leading to a decrease in
the current efficiency and the rhenium content
in the alloy, was previously interpreted by the
authors as a change in the catalytic properties
of the surface as the alloy is deposited. Despite
the convincingness of the catalytic mechanism
of alloy electrodeposition, subsequent works
by these authors are aimed at clarifying the
possibility of interaction between the compo-
nents of the electrolyte, which determines the
previously discovered interdependencies of the
current yields and metal concentrations in the
alloy on the ratio of component concentrations
in the solution. In the study [15], the concept of
weak ionic interaction in electrolytes was pro-
posed, which was verified based on conduc-
tometry, UV-visible and Raman spectroscopy
data. The dependences of the intensity ratios
in the spectra related to different vibrations in
perrhenate ions indicate some deformation of
64 ISSN 2708-129X. Укр. хім. журн., 2025
PROPOSED COMPOSITION OF COMPLEXES AND ION ASSOCIATES IN CITRIC ACID SOLUTIONS
CONTAINING NICKEL SULFAMATE AND POTASSIUM PERRHENATE.PHISICAL CHEMISTRY
these ions, and, as a consequence, the nickel-
citrate complex, due to their interaction in
the electrolyte. However, the formation of the
ternary complex «nickel-citrate-perrhenate»
was not confirmed. No evidence of perrhenate
complexes with the other two components of
the electrolyte was also found. However, the
increasing deformation of the perrhenate ions
with increasing molar ratio [NiCit]−/ReO4
− was
clearly demonstrated by Raman spectroscopy.
Therefore, the weak interaction of these ions
in solution is definitely observed and is strong
enough both to change the shape of ReO4
− and
[NiCit]− or [NiHCit] particles in solution and
to increase the alloy deposition rate. In this
case, it seems to the authors that the induced
interaction is a catalytic process involving the
stage of simultaneous reduction of ReO4
− and
[NiCit]− or [NiHCit] particles, which mutually
influence each other due to the weak interac-
tion in solution. In [16], rhenium-nickel-cit-
rate electrolytes of different compositions were
studied by Raman spectroscopy. The peaks
of two main bonds in ReO4
-, at 972 cm-1 and
331 cm-1, were attributed to the symmetric
Re=O stretching and O-Re-O deformation,
respectively. It was shown that the ratio of
these intensity peaks decreases with increa
sing Ni ion concentration and Ni/Re ion ratio
in the electrolyte. The effect of Ni-Cit ions on
the vibrations of the atom in ReO4
- denotes
the deformation of ReO4
- ions. Based on these
results, the authors suggested some interac-
tion of Ni-Cit ions with ReO4
-, leading to their
deformation. It was assumed that the interac-
tion was weak, since no shift in fundamental
positions was observed. In addition, no com-
plexes of ReO4
- and Ni ions were observed in
citrate electrolytes using UV-V spectroscopy
and conductometry methods for identifying
such complexes. Recently, the authors further
confirmed the proposed mechanism experi-
mentally using aberration-corrected spherical
scanning transmission electron microscopy
(STEM) and atom probe tomography to cha
racterize the structures at the atomic scale and
the part-per-million atomic level 3D chemist
ry. A unique combination of multilayered and
columnar Re-Ni structure consisting of thicker
Re and thinner Ni-rich alternating layers was
observed. In this work, the coatings formed
during the initial stage of electrodeposition
of alloy coatings were investigated by the such
methods: Time-of-Flight Secondary-Ion Mass
Spectrometry (TOF-SIMS) and High-Resolu-
tion X-Ray Photoelectron Spectroscopy (HR-
XPS)). The observed results support the con-
cept of a chemical reaction that decays with
increasing deposition time and are consistent
with the changes in the composition of the
catalytic electrode surface during the deposi-
tion process. In all deposited coatings studied,
both bound Re-Ni ions and individual Ni and
Re ions were detected. The intensity associated
with nickel increased significantly in the di-
rection from the substrate-coating interface to
the outer side of the Re-Ni alloy coating. This
trend corresponds to the decrease in rhenium
concentration with increasing deposition time,
and small periodic increases and decreases in
the intensity related to Ni ions were also ob-
served as well as a periodic changes in the in-
tensities related to Re and Re-Ni ion with sput-
tering time. The increase of the Re and Re-Ni
intensities was accompanied by a decrease of Ni
intensity, and vice versa. According to the SIMS
and XPS results, Re-Ni, Re-NiOx (Re-Ni-O,
Re-Ni-O2) and C2H4-O-Re-Ni are present on
the surface, while Re-Ni is present in the bulk,
indicating a significant interaction between Ni
65https://ucj.org.ua
T.V. Maltseva UCJ № 4 / Vol. 91
and Re in the Re-Ni coatings. Although such
interaction cannot be considered as a definitive
proof of simultaneous deposition from a pre-
cursor containing ReO4
- and complexes of the
composition (NiCit)− or (NiCit)2
4−, it is indirect
evidence for this idea. In [17], the dependen
ces of the amount of formed citrate-perrhen-
ate complexes (ReO4∙H2Cit)2- on the pH of the
solution are presented. Based on the acid-base
equilibria described in [17], one can assume
different behavior of solutions of citric acid,
citric acid with the addition of nickel sulfamate,
and citric acid with the addition of nickel
sulfamate and potassium perrhenate with the
sequential addition of alkali, similar to the pro-
cess of potentiometric titration. A quantitative
assessment of the change in the pH of solutions
upon the addition of 1 M KOH, according to
our assumptions, could provide additional in-
formation on the processes occurring in citrate
electrolytes for the deposition of coatings with
the NiRe alloy.
EXPERIMENT AND DISCUSSION OF THE
RESULTS. A solution of citric acid (Cit) contain-
ing 0.32 mol∙dm-3 of citric acid was prepared, as
well as solutions of (Cit-Ni(II)) and (Cit-Ni(II)-
ReO4
-), containing the same concentrations of
citric acid (0.32 mol∙dm-3) and nickel sulfamate
(0.1 mol∙dm-3) and differing in the presence
of perrhenate ions in the composition. The
concentration of potassium perrhenate in the
Cit-Ni(II)-ReO4
- solution was 0.03 mol∙dm-3. The
composition of the solutions for potentiometric
titration is given in Table 1.
Table 1.
Composition of solutions for pH-metric titration.
Solution
С, mol∙dm-3
C6H8O7∙H2O Ni(SO3NH2)2∙4H2O KReO4
-
Cit 0.32 – –
Cit-Ni(II) 0.32 0.1 –
Cit-Ni(II)-ReO4
- 0.32 0.03
The initial pH values of the Cit-Ni(II)
and Cit-Ni(II)-ReO4
- solutions were the same:
1.56 pH units, and 1.81 pH units for the Cit
solution (16 °C). Precisely measured volumes
of 1 M KOH solution were added to the solu-
tions, mixed for 30–40 min, and the equilib-
rium pH values were measured. Figure 1(a)
shows the dependences of the equilibrium pH
values of Cit, Cit-Ni(II) and Cit-Ni(II)-ReO4
-
solutions after adding a 1 M KOH solution.
From the obtained dependences, the pH values
of all three solutions were extracted to calcu-
late the change in the proton concentration in
the Cit-Ni(II) and Cit-Ni(II)-ReO4
- solutions in
relation to the proton concentration in the Cit
solution during titration with 1 M KOH:
∆CН+ = 10-pH(1) – 10-pH(2) (1),
where pH(1) and pH(2) are the equilibrium
values in Cit-Ni(II) (or Cit-Ni(II)-ReO4
-) and
Cit solutions after addition of 1 M KOH. The
calculations results are shown in Fig. 1(b),
changing of additional OH- and H+ concentra-
tion ∆CН+, ∆COH- are summarized.
66 ISSN 2708-129X. Укр. хім. журн., 2025
PROPOSED COMPOSITION OF COMPLEXES AND ION ASSOCIATES IN CITRIC ACID SOLUTIONS
CONTAINING NICKEL SULFAMATE AND POTASSIUM PERRHENATE.PHISICAL CHEMISTRY
The release of protons into a Cit solution
upon addition of alkali can be described by the
equation:
H3Cit + OH- => H2Cit- + H2O (2)
(curve 1 in Fig. 1(a))
Fig. 1 – Results of pH-metric titration of solu-
tions: Cit (1), Cit-Ni(II) (2), Cit-Ni(II)-ReO4
- (3) (a)
and the total change in proton concentration in
solutions of Cit-Ni(II) (1), Cit-Ni(II)-ReO4
- (2) in
relation to Cit after addition of KOH solution; (3) –
the difference between curves (2) and (1).
The release of protons into the Cit-Ni(II)
solution occurs according to the well-known
reaction of the formation of a protonated ni
ckel complex.
As follows from the results presented in
Fig. 1, in the presence of perrhenate ions in a
solution containing citrate and nickel, another
reaction occurs, accompanied by the release of
a certain amount of protons.
This reaction could be represented as the
addition of perrhenate ions to the NiCitH
complex already present in the solution, and
“weak ionic interaction” occur in the solution
in accordance with the assumptions set out in
[15]):
XNiCitH + YReO4
- => YNiCitReO4
- +
+ (X-Y)NiCitH + YH+ (3)
0.1 NiCitH + 0.032ReO4
- => 0.032NiCitReO4
-
+ 0.068NiCitH + 0.032H+ (4),
or it can be related to the occurrence of a reac-
tion between citrate ions and perrhenate ions
that is independent of the presence of nickel
ions (reactions 4, 5 [18]):
ReO4
- + H3Cit => (ReO4∙H2Cit)2- + H+ (5)
ReO4
- + H2Cit- => (ReO4∙H2Cit)2-. (6)
Reaction (5) can occur simultaneously with
reaction (4), affecting the total number of pro-
tons released into solution and reducing the
stoichiometric number of protons in accor
dance with reaction (4).
But, based on the parallel release of pro-
tons in these two solutions upon addition
of alkali, reactions accompanied by the re-
lease of protons, as can be assumed, occur
with the same citric acid ions, i.e. the forma-
tion of the corresponding amount of NiCit-
ReO4
- occurs according to reaction (3), (4).
In more detail, this complex can be written as
HO-C3-(COO-)3NiReO4
- in which nickel can
be bound, as an assumption, to one of the car-
4
and complexes of the composition (NiCit)− or (NiCit)2
4− , it is indirect evidence for this idea.
In [17], the dependences of the amount of formed citrate-perrhenate complexes
(ReO4∙H2Cit)2- on the pH of the solution are presented. Based on the acid-base equilibria
described in [17], one can assume different behavior of solutions of citric acid, citric acid with
the addition of nickel sulfamate, and citric acid with the addition of nickel sulfamate and
potassium perrhenate with the sequential addition of alkali, similar to the process of
potentiometric titration. A quantitative assessment of the change in the pH of solutions upon the
addition of 1 M KOH, according to our assumptions, could provide additional information on the
processes occurring in citrate electrolytes for the deposition of coatings with the NiRe alloy.
EXPERIMENT AND DISCUSSION OF THE RESULTS. A solution of citric acid (Cit)
containing 0.32 mol∙dm-3 of citric acid was prepared, as well as solutions of (Cit-Ni(II)) and (Cit-
Ni(II)-ReO4
-), containing the same concentrations of citric acid (0.32 mol∙dm-3) and nickel
sulfamate (0.1 mol∙dm-3) and differing in the presence of perrhenate ions in the composition. The
concentration of potassium perrhenate in the Cit-Ni(II)-ReO4
- solution was 0.03 mol∙dm-3. The
composition of the solutions for potentiometric titration is given in Table 1.
Table 1.
Composition of solutions for pH-metric titration.
Solution С, mol∙dm-3
C6H8O7∙H2O Ni(SO3NH2)2∙4H2O KReO4
-
Cit 0.32 – –
Cit-Ni(II) 0.32 0.1 –
Cit-Ni(II)-ReO4
- 0.32 0.03
The initial pH values of the Cit-Ni(II) and Cit-Ni(II)-ReO4
- solutions were the same: 1.56
pH units, and 1.81 pH units for the Cit solution (16 °C). Precisely measured volumes of 1 M
KOH solution were added to the solutions, mixed for 30–40 min, and the equilibrium pH values
were measured. Figure 1(a) shows the dependences of the equilibrium pH values of Cit, Cit-
Ni(II) and Cit-Ni(II)-ReO4
- solutions after adding a 1 M KOH solution. From the obtained
dependences, the pH values of all three solutions were extracted to calculate the change in the
proton concentration in the Cit-Ni(II) and Cit-Ni(II)-ReO4
- solutions in relation to the proton
concentration in the Cit solution during titration with 1 M KOH:
CН+ = 10-pH(1) – 10-pH(2) (1),
where pH(1) and pH(2) are the equilibrium values in Cit-Ni(II) (or Cit-Ni(II)-ReO4
-) and
Cit solutions after addition of 1 M KOH. The calculations results are shown in Fig. 1(b),
changing of additional OH- and H+ concentration CН+, COH- are summarized.
The release of protons into a Cit solution upon addition of alkali can be described by the
equation:
H3Cit + OH- => H2Cit- + H2O (1) (curve 1 in Fig. 1(a))
V KOH, ml
0 10 20 30
рН
1
2
3
4
5
1.82
2.02
1
2
(а)
3
sum ofCOH-, eq/l
0.05 0.10 0.15 0.20 0.25
0.05
0.10
0.15
1
2
sum of СH+, eq/l
3
(b)
4
and complexes of the composition (NiCit)− or (NiCit)2
4− , it is indirect evidence for this idea.
In [17], the dependences of the amount of formed citrate-perrhenate complexes
(ReO4∙H2Cit)2- on the pH of the solution are presented. Based on the acid-base equilibria
described in [17], one can assume different behavior of solutions of citric acid, citric acid with
the addition of nickel sulfamate, and citric acid with the addition of nickel sulfamate and
potassium perrhenate with the sequential addition of alkali, similar to the process of
potentiometric titration. A quantitative assessment of the change in the pH of solutions upon the
addition of 1 M KOH, according to our assumptions, could provide additional information on the
processes occurring in citrate electrolytes for the deposition of coatings with the NiRe alloy.
EXPERIMENT AND DISCUSSION OF THE RESULTS. A solution of citric acid (Cit)
containing 0.32 mol∙dm-3 of citric acid was prepared, as well as solutions of (Cit-Ni(II)) and (Cit-
Ni(II)-ReO4
-), containing the same concentrations of citric acid (0.32 mol∙dm-3) and nickel
sulfamate (0.1 mol∙dm-3) and differing in the presence of perrhenate ions in the composition. The
concentration of potassium perrhenate in the Cit-Ni(II)-ReO4
- solution was 0.03 mol∙dm-3. The
composition of the solutions for potentiometric titration is given in Table 1.
Table 1.
Composition of solutions for pH-metric titration.
Solution С, mol∙dm-3
C6H8O7∙H2O Ni(SO3NH2)2∙4H2O KReO4
-
Cit 0.32 – –
Cit-Ni(II) 0.32 0.1 –
Cit-Ni(II)-ReO4
- 0.32 0.03
The initial pH values of the Cit-Ni(II) and Cit-Ni(II)-ReO4
- solutions were the same: 1.56
pH units, and 1.81 pH units for the Cit solution (16 °C). Precisely measured volumes of 1 M
KOH solution were added to the solutions, mixed for 30–40 min, and the equilibrium pH values
were measured. Figure 1(a) shows the dependences of the equilibrium pH values of Cit, Cit-
Ni(II) and Cit-Ni(II)-ReO4
- solutions after adding a 1 M KOH solution. From the obtained
dependences, the pH values of all three solutions were extracted to calculate the change in the
proton concentration in the Cit-Ni(II) and Cit-Ni(II)-ReO4
- solutions in relation to the proton
concentration in the Cit solution during titration with 1 M KOH:
CН+ = 10-pH(1) – 10-pH(2) (1),
where pH(1) and pH(2) are the equilibrium values in Cit-Ni(II) (or Cit-Ni(II)-ReO4
-) and
Cit solutions after addition of 1 M KOH. The calculations results are shown in Fig. 1(b),
changing of additional OH- and H+ concentration CН+, COH- are summarized.
The release of protons into a Cit solution upon addition of alkali can be described by the
equation:
H3Cit + OH- => H2Cit- + H2O (1) (curve 1 in Fig. 1(a))
V KOH, ml
0 10 20 30
рН
1
2
3
4
5
1.82
2.02
1
2
(а)
3
sum ofCOH-, eq/l
0.05 0.10 0.15 0.20 0.25
0.05
0.10
0.15
1
2
sum of СH+, eq/l
3
(b)
67https://ucj.org.ua
T.V. Maltseva UCJ № 4 / Vol. 91
boxyl groups, and the perrhenate ion – to two.
It is also likely that the acidic residue of per-
rhenate can be bound to the alcohol group of
citrate («weak ionic interaction», [15]):
ReO4- + HO-C3-(COO-)3НNi + OH- =>
=> ReO4- C3-(COO-)3НNi + H2O. (7)
In both cases, the formation of a complex
or, rather, an ionic associate in solution takes
place, binding rhenium and nickel in a 1:1 ra-
tio, as was first suggested back in 1985 by the
H. Fukushima.
What conclusions can be drawn from the
results presented in Fig. 1(b)? Firstly, the total
concentration of protons released into the solu-
tion in both cases – for the Cit-Ni(II) solution
and for the Cit-Ni(II)-ReO4
- solution, in the
first approximation, corresponds to the total
concentration of the components of the solu-
tions. This gives grounds for assuming that the
corresponding reactions occur – the formation
of the citrate complex and reactions (5) and/
or (6). Almost all nickel ions in the solution
are converted into the citrate complex, since
the total concentration of reacted protons is
close to 0.1 mol∙dm-3. Secondly, since the total
concentration of reacted protons in the solu-
tion with perrhenate corresponds to the sum
of the concentrations of nickel and perrhenate,
this confirms that reaction (5), (6) occurs si-
multaneously (in parallel) with the reaction of
the formation of the nickel-citrate complex.
When converting the pH value of the solution
containing all components to the alkaline re-
gion, the predominant citrate complex of ni
ckel will be the NiCit2
4- form [1]. Thus, under
the conditions of NiRe alloy precipitation (pH
not lower than 5 and nickel concentration of
0.1 mol∙dm-3), the NiCit2
4- form is present in
the solution in a significant amount, increa
sing to a maximum value with an increase in
the concentration of citrate ions. At an eleva
ted temperature, at which the alloy is precipi-
tated, the addition of perrhenate ions with the
formation of an ionic associate of the NiCit2
4-
form and 2 ReO4
- ions becomes more likely.
To establish the type of influence of citrate
concentration and the ratio of electrolyte com-
ponents on the alloy composition, the data
from [2, 7, 4] were analyzed. Fig. 2 shows the
dependences of the ratio of alloy component
concentrations (Ni, Re) on the ratio of the
concentrations of the components of the ionic
components of the solution (Ni, Re, Cit). The
alloys were deposited at a current of 25 [7] –
50 [2] mA∙cm-2.
The dependences in Fig. 2 show that the
concentration of citrate ions significantly af-
fects the ratio of components in the alloy and
partial currents. It should be taken into account
that an increase in the concentration of citrate
ions in the nickel-citrate system leads to an in-
crease in the proportion of the NiCit2
4- com-
plex [1]. Similarly, an increase in the concent
ration of iron subgroup metal ions in the solu-
tion leads to an increase in the concentration
of this complex. In [1] on Fig 1(b) the concen-
tration distribution of Ni2+-Cit3– complexes as
a function of the overall citrate concentration
(0.1 M NiSO4, pH = 8.0) is shown. From the
data it can be concluded that sharp arising of
NiCit2
4- concentration occurs along concentra-
tion of citrate in solution. Therefore, it is this
complex, capable of adding two perrhenate
ions to form the corresponding ionic associate
NiCit2(ReO4)2, that can play a significant role in
the process of electrodeposition of NiRe alloys.
The concentration of NiCit2(ReO4)2 should be
very high, respectively, under conventional
conditions of the alloys electrodeposition.
68 ISSN 2708-129X. Укр. хім. журн., 2025
PROPOSED COMPOSITION OF COMPLEXES AND ION ASSOCIATES IN CITRIC ACID SOLUTIONS
CONTAINING NICKEL SULFAMATE AND POTASSIUM PERRHENATE.PHISICAL CHEMISTRY
Fig. 2 – The ratio of Re to Ni concentrations in
the NiRe alloy on the ratio of their ion concentra-
tions in the solution: 1, 2, 3 [2], 4 [7]; the ratio of
the concentrations of citrate ions and nickel ions:
3:1 (1), 2:1 (3), 1:1 (2, 4) (a) and the ratio of rheni-
um to nickel partial currents of deposition on the
ratio of the concentrations of citrate ions and nickel
ions [4].
Based on the concentrations of nickel and
rhenium in the alloy, in accordance with the
results of the study [4], the estimated concent
rations of complexes and ionic associates in the
electrolyte were calculated.
Figure 3 is constructed based on the data of
work [4] (Fig. 3(a), averaged data) and the esti-
mated calculation of the ratio of various comp
lexes (NiCitReO4
-; NiHCit; NiCit-; NiCit2H2;
NiCit2(ReO4
-)2) in the electrolyte of the com-
position, mmol: ReO4
- – 34; Ni2+ – 93; Cit –
(93-340). Experimental results and calculation
are represented for the given deposition cur-
rent density of 50 mA∙cm-2.
Fig. 3 – The ratio of the concentrations of the
alloy components depending on their ratio in the
composition of the supposed complexes contained
in the electrolyte.
Examples of calculation:
1. C(Cit):C(Ni2+) = 1:1 and [Re]:[Ni]alloy =
18:82 (point 0.22 on the Y coordinate axis).
By analogy with the equation (3) we can
write:
0.034NiCitReO4
- + 0.066NiCit-, and point
on the X coordinate axis will be 0.034/0.066 =
0.34
2. C(Cit):C(Ni2+) = 2:1 and [Re]:[Ni]alloy =
40:60 (point 0.67 on Y coordinate axis).
By analogy with the equation (3) we can
write:
6
dependences of the ratio of alloy component concentrations (Ni, Re) on the ratio of the
concentrations of the components of the ionic components of the solution (Ni, Re, Cit). The
alloys were deposited at a current of 25 [7] – 50 [2] mA∙cm-2.
С(ReO4
-):C(Ni2+)
0.0 0.2 0.4 0.6 0.8 1.0 1.2
lg([Re]:[Ni]alloy)
-1
0
1
2
3
1
2
4
(a)
C(Cit):C(Ni2+)
0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0
lg(iRe:iNi)
-0.5
0.0
0.5
1.0
(b)
Fig. 2 – The ratio of Re to Ni concentrations in the NiRe alloy on the ratio of their ion
concentrations in the solution: 1, 2, 3 [2], 4 [7]; the ratio of the concentrations of citrate ions and nickel
ions: 3:1 (1), 2:1 (3), 1:1 (2, 4) (a) and the ratio of rhenium to nickel partial currents of deposition on the
ratio of the concentrations of citrate ions and nickel ions [4].
The dependences in Fig. 2 show that the concentration of citrate ions significantly affects
the ratio of components in the alloy and partial currents. It should be taken into account that an
increase in the concentration of citrate ions in the nickel-citrate system leads to an increase in the
proportion of the NiCit2
4- complex [1]. Similarly, an increase in the concentration of iron
subgroup metal ions in the solution leads to an increase in the concentration of this complex. In
[1] on Fig 1(b) the concentration distribution of Ni2+-Cit3– complexes as a function of the overall
citrate concentration (0.1 M NiSO4, pH = 8.0) is shown. From the data it can be concluded that
sharp arising of NiCit2
4- concentration occurs along concentration of citrate in solution.
Therefore, it is this complex, capable of adding two perrhenate ions to form the corresponding
ionic associate NiCit2(ReO4)2, that can play a significant role in the process of electrodeposition
of NiRe alloys. The concentration of NiCit2(ReO4)2 should be very high, respectively, under
conventional conditions of the alloys electrodeposition.
Based on the concentrations of nickel and rhenium in the alloy, in accordance with the
results of the study [4], the estimated concentrations of complexes and ionic associates in the
electrolyte were calculated.
Figure 3 is constructed based on the data of work [4] (Fig. 3(a), averaged data) and the
estimated calculation of the ratio of various complexes (NiCitReO4
-; NiHCit; NiCit-; NiCit2H2;
NiCit2(ReO4
-)2) in the electrolyte of the composition, mmol: ReO4
- – 34; Ni2+ – 93; Cit – (93-
340). Experimental results and calculation are represented for the given deposition current
density of 50 mA∙cm-2.
6
dependences of the ratio of alloy component concentrations (Ni, Re) on the ratio of the
concentrations of the components of the ionic components of the solution (Ni, Re, Cit). The
alloys were deposited at a current of 25 [7] – 50 [2] mA∙cm-2.
С(ReO4
-):C(Ni2+)
0.0 0.2 0.4 0.6 0.8 1.0 1.2
lg([Re]:[Ni]alloy)
-1
0
1
2
3
1
2
4
(a)
C(Cit):C(Ni2+)
0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0
lg(iRe:iNi)
-0.5
0.0
0.5
1.0
(b)
Fig. 2 – The ratio of Re to Ni concentrations in the NiRe alloy on the ratio of their ion
concentrations in the solution: 1, 2, 3 [2], 4 [7]; the ratio of the concentrations of citrate ions and nickel
ions: 3:1 (1), 2:1 (3), 1:1 (2, 4) (a) and the ratio of rhenium to nickel partial currents of deposition on the
ratio of the concentrations of citrate ions and nickel ions [4].
The dependences in Fig. 2 show that the concentration of citrate ions significantly affects
the ratio of components in the alloy and partial currents. It should be taken into account that an
increase in the concentration of citrate ions in the nickel-citrate system leads to an increase in the
proportion of the NiCit2
4- complex [1]. Similarly, an increase in the concentration of iron
subgroup metal ions in the solution leads to an increase in the concentration of this complex. In
[1] on Fig 1(b) the concentration distribution of Ni2+-Cit3– complexes as a function of the overall
citrate concentration (0.1 M NiSO4, pH = 8.0) is shown. From the data it can be concluded that
sharp arising of NiCit2
4- concentration occurs along concentration of citrate in solution.
Therefore, it is this complex, capable of adding two perrhenate ions to form the corresponding
ionic associate NiCit2(ReO4)2, that can play a significant role in the process of electrodeposition
of NiRe alloys. The concentration of NiCit2(ReO4)2 should be very high, respectively, under
conventional conditions of the alloys electrodeposition.
Based on the concentrations of nickel and rhenium in the alloy, in accordance with the
results of the study [4], the estimated concentrations of complexes and ionic associates in the
electrolyte were calculated.
Figure 3 is constructed based on the data of work [4] (Fig. 3(a), averaged data) and the
estimated calculation of the ratio of various complexes (NiCitReO4
-; NiHCit; NiCit-; NiCit2H2;
NiCit2(ReO4
-)2) in the electrolyte of the composition, mmol: ReO4
- – 34; Ni2+ – 93; Cit – (93-
340). Experimental results and calculation are represented for the given deposition current
density of 50 mA∙cm-2.
7
[Re]:[Ni]solution
0.0 0.5 1.0 1.5 2.0 2.5
[Re]:[Ni]alloy
1
2
3 3.7
3.0
2.0
1.51
citrate-to-nickel ratio
Fig. 3 – The ratio of the concentrations of the alloy components depending on their ratio in the
composition of the supposed complexes contained in the electrolyte.
Examples of calculation:
1. C(Cit):C(Ni2+) = 1:1 and [Re]:[Ni]alloy = 18:82 (point 0.22 on the Y coordinate axis).
By analogy with the equation (3) we can write:
0.034NiCitReO4
- + 0.066NiCit-, and point on the X coordinate axis will be 0.034/0.066 =
0.34
2. C(Cit):C(Ni2+) = 2:1 and [Re]:[Ni]alloy = 40:60 (point 0.67 on Y coordinate axis).
By analogy with the equation (3) we can write:
0.034NiCitReO4
- + 0.066NiCit- + 0.1Cit3- => 0.034NiCitReO4
- + 0.023NiCit- + 0.043NiCit2
4- +
0.057Cit3-
and point on the X coordinate axis will be 0.034/0.057 = 0.6, because of NiCit2
4- is
electrochemically inactive form, and shouldn’t be calculated.
3. C(Cit):C(Ni2+) = 3.7:1 and [Re]:[Ni]alloy = 75:25 (point 3 on Y coordinate axis).
By analogy with the equation (3) we can write:
0.034NiCitReO4
- + 0.066NiCit- + 0.2 Cit3- => 0.034NiCitReO4
- + 0NiCit- +0.07 NiCit2
4- + 0.13Cit =>
=> 0.025NiCit2(ReO4)2 + 0.005NiCitReO4
-
and point on the X coordinate axis will be 0.034/0.057 = 2.2.
CONCLUSIONS. The article presents an analysis of the experimental data available in the
scientific literature on the conditions for obtaining nickel-rhenium alloys, promising as cathodes
for electrolytic hydrogen production. The problem of searching for additional evidence of the
mutual influence and interaction of nickel(II), citrate and perrhenate ions in the deposition
electrolyte is formulated. For this purpose pH-metric titration of solutions containing (1) only
citrate; (2)citrate and nickel(II); (3)citrate, nickel(II) and potassium perrhenate in the pH range
from 1.5 to 2.0 was carried out. Simultaneous release of protons associated with both the
reaction of nickel with citrate to form the corresponding NiHCit complex and the reaction of
citrate with perrhenate was shown.
Based on the analysis of experimental results concerning the influence of the components of
nickel-rhenium alloy deposition electrolytes on electrodeposition results, it was concluded that
the predominant form providing the observed results in high current yield and rhenium content in
the alloy is an electrochemically inactive ion associate consisting of the NiCit2
4- complex and
two perrhenate ions. Destroying in the near-electrode layer, it provides a periodic predominance
of perrhenate ions, which can be restored without kinetic difficulties. The composition of
complexes and ionic associates is proposed for a wide range of experimental data on the induced
deposition of nickel-rhenium alloy coatings from citrate electrolytes, based on the quantitative
ratios of the components in the electrolyte and the pH value.
69https://ucj.org.ua
T.V. Maltseva UCJ № 4 / Vol. 91
0.034NiCitReO4
- + 0.066NiCit- + 0.1Cit3- =>
=> 0.034NiCitReO4
- + 0.023NiCit- +
+ 0.043NiCit2
4- + 0.057Cit3-
and point on the X coordinate axis will be
0.034/0.057 = 0.6, because of NiCit2
4- is electro
chemically inactive form, and shouldn’t be cal-
culated.
3. C(Cit):C(Ni2+) = 3.7:1 and [Re]:[Ni]alloy =
75:25 (point 3 on Y coordinate axis).
By analogy with the equation (3) we can
write:
0.034NiCitReO4
- + 0.066NiCit- + 0.2 Cit3- =>
=> 0.034NiCitReO4
- + 0NiCit- +0.07 NiCit2
4- +
+ 0.13Cit => 0.025NiCit2(ReO4)2 +
+ 0.005NiCitReO4
-
and point on the X coordinate axis will be
0.034/0.057 = 2.2.
CONCLUSIONS. The article presents an
analysis of the experimental data available in
the scientific literature on the conditions for
obtaining nickel-rhenium alloys, promising
as cathodes for electrolytic hydrogen produc-
tion. The problem of searching for additional
evidence of the mutual influence and interac-
tion of nickel(II), citrate and perrhenate ions
in the deposition electrolyte is formulated. For
this purpose pH-metric titration of solutions
containing (1) only citrate; (2)citrate and ni
ckel(II); (3)citrate, nickel(II) and potassium
perrhenate in the pH range from 1.5 to 2.0
was carried out. Simultaneous release of pro-
tons associated with both the reaction of nickel
with citrate to form the corresponding NiHCit
complex and the reaction of citrate with per-
rhenate was shown.
Based on the analysis of experimental re-
sults concerning the influence of the com-
ponents of nickel-rhenium alloy deposition
electrolytes on electrodeposition results, it was
concluded that the predominant form provi
ding the observed results in high current yield
and rhenium content in the alloy is an electro-
chemically inactive ion associate consisting of
the NiCit2
4- complex and two perrhenate ions.
Destroying in the near-electrode layer, it pro-
vides a periodic predominance of perrhenate
ions, which can be restored without kinetic
difficulties. The composition of complexes and
ionic associates is proposed for a wide range of
experimental data on the induced deposition
of nickel-rhenium alloy coatings from citrate
electrolytes, based on the quantitative ratios of
the components in the electrolyte and the pH
value.
The work was carried out with the fi-
nancial support of the National Aca
demy of Science of Ukraine within the
state budget topic 328-E «Finishing of
materials in order to give them unique
functional properties», the state regist
ration number: 0123U100650.
ВІРОГІДНИЙ СКЛАД КОМПЛЕКСІВ ТА
ІОННИХ АСОЦІАТІВ У РОЗЧИНАХ ЛИМОННОЇ
КИСЛОТИ, ЩО МІСТЯТЬ СУЛЬФАМАТ
НІКЕЛЮ І ПЕРРЕНАТ КАЛІЯ
Т. В. Мальцева
Інститут загальної та неорганічної хімії
ім. В. І. Вернадського НАН України,
просп. Академіка Палладіна, 32/34, Київ
03142, Україна
∗e-mail: maltseva50tv@gmail.com
У статті представлено аналіз наявних у
науковій літературі експериментальних да-
них про умови отримання нікель-ренієвих
70 ISSN 2708-129X. Укр. хім. журн., 2025
PROPOSED COMPOSITION OF COMPLEXES AND ION ASSOCIATES IN CITRIC ACID SOLUTIONS
CONTAINING NICKEL SULFAMATE AND POTASSIUM PERRHENATE.PHISICAL CHEMISTRY
сплавів, перспективних як катоди для елект
ролітичного отримання водню. Сформу-
льовано завдання пошуку додаткових до-
казів взаємного впливу та взаємодії іонів
нікелю(II), цитрату та перренату в електро-
літі осадження. Проведено рН-метричне
титрування розчинів, що містять (1) тільки
цитрат; (2) цитрат та нікель (II); (3) цитрат,
нікель (II) та перренат калію в діапазоні рН
від 1.5 до 2.0. Показано одночасне виділен-
ня протонів, пов’язане як із реакцією ніке-
лю з цитратом з утворенням відповідного
комплексу NiHCit-, так і з реакцією цитра-
ту з перренатом з утворенням комплексу
(ReO4∙H2Cit)2-. На підставі аналізу даних
щодо впливу компонентів електролітів оса-
дження нікель-ренієвих сплавів на резуль-
тати електроосадження зроблено висновок
про те, що переважною формою, що за-
безпечує результати з високим виходом за
струмом і вмісту ренію в сплаві, є іонний
асоціат, що складається з комплексу NiCit2
4-
та двох перренат-іонів. Руйнування цієї
електрохімічно неактивної форми в при
електродному шарі призводить до періодич-
ного суттєвого збільшення концентрації
перренат-іонів, які можуть відновлюватися
без кінетичних труднощів. На підставі літе-
ратурних експериментальних даних щодо
індукованого осадження покриттів спла-
вом нікель – реній з цитратних електролітів
запропоновано варіанти співвідношення
комплексів та іонних асоціатів залежно від
складу електроліту та значення pH.
Ключові слова: сплави нікель – реній,
цитратні комплекси, іонна взаємодія,
pH-титрування, склад електроліту, розра-
хунки.
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Cтаття надійшла 07.02.2025.
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| id | oai:ojs2.1444248.nisspano.web.hosting-test.net:article-716 |
| institution | Ukrainian Chemistry Journal |
| keywords_txt_mv | keywords |
| language | English |
| last_indexed | 2026-07-23T01:12:55Z |
| publishDate | 2025 |
| publisher | V.I.Vernadsky Institute of General and Inorganic Chemistry |
| record_format | ojs |
| resource_txt_mv | ucjorgua/ab/bfe2d1e9b912f8c84b90433787ad4aab.pdf |
| spelling | oai:ojs2.1444248.nisspano.web.hosting-test.net:article-7162026-07-22T08:23:55Z PROPOSED COMPOSITION OF COMPLEXES AND ION ASSOCIATES IN CITRIC ACID SOLUTIONS CONTAINING NICKEL SULFAMATE AND POTASSIUM PERRHENATE(Review) Maltseva, Tetiana nickel-rhenium alloys, citrate complexes, ion interaction, pH-titration, electrolyte composition, calculations. The article presents an analysis of the experimental data available in the scientific literature on the conditions for obtaining nickel-rhenium alloys, promising as cathodes for electrolytic hydrogen production. The problem of searching for additional evidence of the mutual influence and interaction of nickel (II), citrate and perrhenate ions in the deposition electrolyte is formulated. For this purpose pH-metric titration of solutions containing (1) citrate ions only; (2) citrate and nickel(II) ions; (3) citrate, nickel(II) and potassium perrhenate ions – was carried out in the pH range from 1.5 to 2.0. Simultaneous release of protons associated with both the reaction of nickel with citrate to form the corresponding NiHCit- complexes and the reaction of citrate with perrhenate to form the (ReO4∙H2Cit)2- complexes was shown. Since the total concentration of reacted protons in the solution with nickel (II) and perrhenate corresponds to the sum of the concentrations of nickel and perrhenate ions, this confirms that reaction of complexes of citrate/perrenate formation occurs simultaneously (in parallel) with the reaction of the formation of the nickel-citrate complexes. And further pH arising should lead to well-known formation of NiCit24- complexes, which can be associated with two ions of perrenate. Based on the analysis of date concerning the influence of the components of nickel-rhenium alloy deposition electrolytes on electrodeposition results, it was concluded that the predominant form providing the observed results concern both high current yield and high rhenium content in the alloy is an electrochemically inactive ion associate consisting of the NiCit24- complex and two perrhenate ions. Destroying in the near-cathode solution layer, it provides a periodic predominance of perrhenate ions, which can be restored without kinetic difficulties. The composition of complexes and ionic associates is proposed for a wide range of experimental data on the induced deposition of nickel-rhenium alloy coatings from citrate electrolytes, based on the quantitative ratios of the complex components in the electrolyte and the pH value. V.I.Vernadsky Institute of General and Inorganic Chemistry 2025-05-25 Article Article Physical chemistry Физическая xимия Фізична xімія application/pdf https://ucj.org.ua/index.php/journal/article/view/716 10.33609/2708-129X.91.4.2025.61-71 Ukrainian Chemistry Journal; Vol. 91 No. 4 (2025): Ukrainian Chemistry Journal; 61-71 Украинский химический журнал; ##issue.vol## 91 ##issue.no## 4 (2025): Ukrainian Chemistry Journal; 61-71 Український хімічний журнал; Том 91 № 4 (2025): Ukrainian Chemistry Journal; 61-71 2708-129X 2708-1281 en https://ucj.org.ua/index.php/journal/article/view/716/364 Copyright (c) 2025 Tetiana Maltseva https://creativecommons.org/licenses/by-nc/4.0 |
| spellingShingle | Maltseva, Tetiana PROPOSED COMPOSITION OF COMPLEXES AND ION ASSOCIATES IN CITRIC ACID SOLUTIONS CONTAINING NICKEL SULFAMATE AND POTASSIUM PERRHENATE(Review) |
| title | PROPOSED COMPOSITION OF COMPLEXES AND ION ASSOCIATES IN CITRIC ACID SOLUTIONS CONTAINING NICKEL SULFAMATE AND POTASSIUM PERRHENATE(Review) |
| title_full | PROPOSED COMPOSITION OF COMPLEXES AND ION ASSOCIATES IN CITRIC ACID SOLUTIONS CONTAINING NICKEL SULFAMATE AND POTASSIUM PERRHENATE(Review) |
| title_fullStr | PROPOSED COMPOSITION OF COMPLEXES AND ION ASSOCIATES IN CITRIC ACID SOLUTIONS CONTAINING NICKEL SULFAMATE AND POTASSIUM PERRHENATE(Review) |
| title_full_unstemmed | PROPOSED COMPOSITION OF COMPLEXES AND ION ASSOCIATES IN CITRIC ACID SOLUTIONS CONTAINING NICKEL SULFAMATE AND POTASSIUM PERRHENATE(Review) |
| title_short | PROPOSED COMPOSITION OF COMPLEXES AND ION ASSOCIATES IN CITRIC ACID SOLUTIONS CONTAINING NICKEL SULFAMATE AND POTASSIUM PERRHENATE(Review) |
| title_sort | proposed composition of complexes and ion associates in citric acid solutions containing nickel sulfamate and potassium perrhenate(review) |
| topic_facet | nickel-rhenium alloys citrate complexes ion interaction pH-titration electrolyte composition calculations. |
| url | https://ucj.org.ua/index.php/journal/article/view/716 |
| work_keys_str_mv | AT maltsevatetiana proposedcompositionofcomplexesandionassociatesincitricacidsolutionscontainingnickelsulfamateandpotassiumperrhenatereview |