Complexing Properties of 3-Substituted-2-(aryl-, methyl)sulfonylamino-4,5,6,7-tetrahydrobenzo[b]thiophenes with Nonferrous Metal Ions in Ammonia Media

Article abstract of DOI:10.1134/S003602361807015X

The complexation of 3-substituted-2-(aryl-,methyl)sulfonylamino-4,5,6,7-tetrahydrobenzo[b]thiophenes with Cu(II), Co(II), and Ni(II) ions in ammonia media was studied. Different types of complexes with Cu(II) ions were found depending on pH: with a ratio of 1: 2 at pH of ~4–5 and 1: 1 at pH of ~ 8–10. For the Co(II) and Ni(II) ions, the formation of 1: 1 complexes at pH of ~9–10 was established. The Cu(II), Co(II), and Ni(II) complexes [Cu(HL)₂. 2H₂O] and [ML. 2H₂O] were separated and identified, and their solubility products were calculated. The effect of the nature of the functional group in the third position of the thiophene ring on the properties of the complexes of reagents with nonferrous metal ions was shown.

Full text of DOI:10.1134/S003602361807015X

ISSN 0036-0236, Russian Journal of Inorganic Chemistry, 2018, Vol. 63, No. 7, pp. 987–992. © Pleiades Publishing, Ltd., 2018.
Original Russian Text © K.O. Manylova, L.G. Chekanova, P.T. Pavlov, E.V. Baigacheva, 2018, published in Zhurnal Neorganicheskoi Khimii, 2018, Vol. 63, No. 7, pp. 943–949.
PHYSICAL CHEMISTRY
OF SOLUTIONS
Complexing Properties of 3-Substituted-2-(aryl-,
methyl)sulfonylamino-4,5,6,7-tetrahydrobenzo[b]thiophenes
with Nonferrous Metal Ions in Ammonia Media
K. O. Manylovaa, *, L. G. Chekanovaa, P. T. Pavlovb, and E. V. Baigachevaa
aInstitute of Technical Chemistry, Ural Branch, Russian Academy of Sciences, Perm, 614013 Russia
bPerm State National Research University, Perm, 614990 Russia
*e-mail: ksenimanilova@mail.ru
Received May 5, 2017
Abstract⎯The
complexation
of
3-substituted-2-(aryl-,methyl)sulfonylamino-4,5,6,7-tetrahydro-
benzo[b]thiophenes with Cu(II), Co(II), and Ni(II) ions in ammonia media was studied. Different types of
complexes with Cu(II) ions were found depending on pH: with a ratio of 1 : 2 at pH of ~4–5 and 1 : 1 at pH
of ~ 8–10. For the Co(II) and Ni(II) ions, the formation of 1 : 1 complexes at pH of ~9–10 was established.
The Cu(II), Co(II), and Ni(II) complexes [Cu(НL)2 ⋅ 2Н2О] and [МL ⋅ 2Н2О] were separated and identi-
fied, and their solubility products were calculated. The effect of the nature of the functional group in the third
position of the thiophene ring on the properties of the complexes of reagents with nonferrous metal ions was
shown.
DOI: 10.1134/S003602361807015X
The attention to the chemistry of 2-amino-3-sub- tuted amide) group in the third position of the thio-
stituted thiophene derivatives is due to both their bio- phene ring in 3-substituted-2-(aryl, methyl)sulfonyl-
activity [1, 2] and the synthesis of diverse polyfunc- amino-4,5,6,7-tetrahydrobenzo[b]thiophenes (STG)
tional heterocyclic compounds on their basis [3, 4]. on their complexing properties with respect to
Being polydentate ligands able of forming complexes NMs(II) (1).
of different composition and structure with metal ions
O
[5–7], they are also of interest as reagents for element
R'
concentration processes. At a considerable number of
reviews and papers (especially in the last decade)
(1)
O
NH S R
O
devoted to the synthesis and application of 2-amino-
3-substituted thiophenes [8–11], there exist few works
reporting the data on the properties, composition, and
structure of the coordination compounds of simple
2-aminothiophenes with nonferrous metals (NMs)
[12]. The information on the properties and complex-
ation of sulfonyl derivatives of 2-amino-3-substituted
thiophenes is also scanty, and all the papers generally
present the data on their bioactivity [13, 14].
S
where R = p-С6H4CH3, R' = OC2H5 (1); OH (2); NH2
(3); NHC6H5 (4); R = CH3, R' = OH (5)
EXPERIMENTAL
Compounds 1, 3, and 4 were synthesized by the
reaction between corresponding thiophenes and tosyl
chloride, and compounds 2 and 5 were prepared by the
hydrolysis of corresponding esters with a water–alco-
hol–dioxane solution of NaOH. The identity and
purity of reagents were confirmed by IR and 1H NMR
spectroscopy data, thin-layer chromatography, and
elemental analysis [18].
In our earlier work [15], it has been shown that
2-sulfonylamino-3-substituted thiophenes with an
ester group in the third position of their thiophene ring
form intracomplex compounds with nonferrous metal
ions with the ratio [M(II)] : [HL] = 1 : 2. A low solu-
bility of these complexes in water and their high solu-
bility in organic solvents (chloroform, isoamyl alco-
hol, hexane, and p-xylene) has provided a basis for the
study of these ligands as collectors for ionic floatation
and extractants [16, 17].
pH measurements were performed on an I-160M
ion meter (ANTEKh) with glass and silver/silver chlo-
The objective of this work was to study the effect of ride electrodes, and conductometric titration was
the nature of a functional (carboxyl, amide, substi- accomplished on an Anion 4100 conductometer (Rus-
987

988
MANYLOVA et al.
A
1.4
1.2
1.0
0.8
0.6
0.4
0.2
0
2
5
3
1
4
200
300
400
500
600
700
800
λ, nm
Fig. 1. Electronic absorption spectra for the water–alcohol (9 : 1) solutions of (1), (3) CuSO , (2) compound 2, and (4, 5) a mix-
4
–4
–3
ture of CuSO with compound 2 at [М(II)] : [H L] = 1 : 2, l = 1 cm,
of (1), (4) 1 × 10 and (3), (5) 4 × 10 mol/L, and
c
CuSO4
4
2
pH of (1, 2, 4) ~ 5 and (3, 5) ~ 9.
sia). The stirring of solutions in the process of titration weakly acidic and alkaline solutions of mixtures indi-
was performed with a PE-6110 magnetic agitator. IR cates the formation of different types of complexes
absorption spectra in the region of 400–4000 cm–1
were recorded on a Bruker Vertex 80V IR Fourier
depending on pH of a medium. The electron absorp-
tion spectra (EASs) of CuSO4–compound 5 mixture
transform spectrometer, UV spectra and the absor- solutions have proven to be similar to the spectra of
bance were measured on an SF-2000 spectrophotom- compound 2. The only blue-violet Cu(II) complex
1
with absorption maxima at 500 and 600 nm was
revealed for compounds 3 and 4, respectively, within a
range of 8 < pH < 10.
eter, and H NMR spectra were taken on a Varian
MERCURY plus 300 spectrometer (United States) in
DMSO-d6 and СDCl3 using hexamethyldisiloxane
(HMDS) as an internal standard. Thermal analysis was
performed on a METTLER TOLEDO TGA/DSC 1LF
thermogravimetric analyzer in an air atmosphere at a
heating rate of 10°C/min. The content of metal ions in
solutions was determined on a Thermo Scientific iCE
3500 atomic absorption spectrometer with flame
atomization. Elemental analysis was performed on
a LECO CHNS-932 analyzer.
The formation of complexes of one type at pH ~ 8–
9 with absorption maxima at 580–600 nm was
observed for Co(II) ions with compounds 2–5. It can
be seen that the reagent and mixture absorption max-
ima in the electron absorption spectra for the mixtures
of reagents with Ni(II) sulfate coincide with each
other at pH ~ 8–9, while the appearance of light-green
color is observed during the preparation of a mixture.
It seems that the Ni(II) complexes with reagents of the
STG series are unstable in an aqueous alcohol solu-
tion.
Complexation processes were studied spectropho-
tometrically [19]. The composition of complexes was
determined by saturation, isomolar series, and con-
ductometric titration [20, 21]. The preparative separa-
tion and analysis of complexes were accomplished by
the method described elsewhere [22].
Composition of the Complexes of Reagents 2 and 5
The methods of saturation, isomolar series, and
conductometric titration showed that the reagents
form green complexes with a ratio of compounds
[Cu(II)] : [H2L] = 1 : 2 at pH ~ 4–5 (Fig. 2, the exam-
ple for compound 2) and violet complexes with a ratio
of 1 : 1 at pH ~ 8–10 (Fig. 3, the example for com-
pound 5). For the Co(II) and Ni(II) ions, the forma-
tion of 1 : 1 complexes only was revealed at pH ~ 9–10
(Fig, 2, the example for compound 2).
RESULTS AND DISCUSSION
The absorption spectra of solutions of copper(II)
sulfate, compound 2, and their mixtures in a water–
alcohol medium at different pH are shown in Fig. 1. It
can be seen that the light absorption maximum of the
mixture solution sustains a bathochromic shift at pH ~
4–5 (λmax = 700 nm) (curve 4) in comparison with the
reagent (λmax = 226 and 306 nm) (curve 2) and the
The complexes of reagent 2 with NMs(II) were
Cu(II) salt (curve 1). The mixture maximum with λmax
=
preparatively separated at the found ratios. It has been
490 nm appears at pH ~ 8–9 (curve 5). An appreciable established that the reagent in the 1 : 2 complex partic-
distinction between the light absorption curves of the ipates in the coordination interaction with Cu(II) ions
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COMPLEXING PROPERTIES
989
I
A
0.6
(a)
0.5
0.4
0.3
0.2
0.1
0
–logAi/(Amax – Ai)
2.0
(b)
1.5
1.0
0.5
tanα = 1.8
–logCH2L
0
2.0 2.2 2.4 2.6 2.8 3.0
[Cu(II)] : [H2L]
0
1 : 0.5 1 : 1 1 : 1.5 1 : 2 1 : 1.25 1 : 3 1 : 3.5
A
0.5
II
(b)
0.4
0.3
0.2
0.1
0
VH2L, mL
0
1
4
2
3
3
2
4
1
5
0
VCo(II), mL
5
Fig. 2. Estimating the ratio of compounds in the NMs(II) complexes of 2-tosylamino-4,5,6,7-tetrahydrobenzo[b]thiophene-3-
–2
carboxylic acid (2). I: (a) saturation method, (b) processing of curve (a) by the equilibrium shift method; c
= c = 1 × 10 mol/L,
2
Cu(II)
water–alcohol (9 : 1) solution (pH ~ 4), c
= 0.1 mol/L; solvent, p-xylene; λ = 689 nm, l = 1 cm; II: method of isomolar series;
KCl
–2
c
= c = 1 × 10 mol/L, ammonia–alcohol solution (pH ~ 9.5), c
= 0.1 mol/L, λ = 400 nm, l = 1 cm.
Сo(II)
2
KCl
in an ionized form, namely, the HL– ion. This is evi-
denced by the fact that the IR spectrum of the com-
plex does not contain the characteristic absorption
bands, which correspond to the stretching vibrations
of carboxyl OH bonds and are observed in the spectra
of the ligands (3300 cm–1). The low-frequency shift of
the absorption band of NH bonds in the spectra of the
complexes (3173 cm–1) in comparison with the ligands
(3186 cm–1) indicates the formation of a donor–
gen atom. The vibrations of water molecules are char-
acterized by the band appearing in the spectrum of the
complex at 3499 cm–1 (Fig. 4).
The presence of water of crystallization is con-
firmed by thermal analysis data: the temperature
region of 170–180°C in the DTG curve contains an
endotherm, which can be assigned to the loss of crys-
tallization water, and the found mass loss of a sample
corresponds to its calculated value in hypothetical
acceptor bond with the Cu(II) ion through the nitro- complexes (calcd./found (%): 4.49/3.89) (Fig. 5).
RUSSIAN JOURNAL OF INORGANIC CHEMISTRY Vol. 63 No. 7 2018

990
MANYLOVA et al.
formula (2) was proposed for the Cu(II) complexes
W, μS/cm
85
[Cu(НL)2 ⋅ 2Н2О]:
80
75
70
65
60
55
R
SO2
O
OH2
Cu
HN
O
S
O
(2)
S
NH
OH2
O
O2S
R
50
0
The solubility products of the complexes were cal-
culated in the same fashion as in the work [15]. The
found values of –logSP for ligands 2 and 5 with Cu(II)
ions are much lower than the values calculated for the
1 : 2 complexes of reagent (1) [15] with an ester group
(Table 2).
2
4
6
8
10
12
VH2L, mL
Fig. 3. Conductometric titration of an ammoniac Cu(II)
solution with a solution of 2-mesylamino-4,5,6,7-tetrahy-
In the work [18], it has been demonstrated that
2-sulfonylamino-3-substituted thiophenes with a car-
boxyl group in the third position of their thiophene
ring are dicarboxylic acids (Н2L). The formation of
a six-membered ring with the doubly ionized form of
a ligand is hypothesized for the NMs(II) 1 : 1 com-
plexes with compounds 2 and 5 and is confirmed by
the elemental analysis data (Table 1). The IR spectra
drobenzo[b]thiophene-3-carboxylic acid (5) at C
=
Cu(II)
–2
С = 1 × 10 mol/L, V
= 5 mL, V = 70 mL (EtOH :
0
5
Cu(II)
Н О = 1 : 1), and pH ~ 10.
2
Based on the results of studying the protolytic equi-
libria, the ionization directions for molecules of
ligands 2 and 5 [18], and the data of IR spectroscopy,
thermal and elemental analysis (Table 1), graphical of the complexes do not contain the characteristic
2.5
2.0
1.5
1.0
1
0.5
2
3
0
4000
1500
3500
3000
2500
2000
N, cm–1
1000
Fig. 4. IR spectra of (1) compound 2, (2) [Cu(НL) ⋅ 2Н О], and (3) [СuL ⋅ 2Н О].
2
2
2
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COMPLEXING PROPERTIES
DSC, W/g
991
TG
100
90
80
70
60
50
40
30
20
10
0
20
10
0
Stage
–3.89%
–0.19 mg
1
2
400
40
200
20
800
80
600
60
T, °C
10
τ, min
0
DTG
0.1
1
2
400
40
200
20
800
80
600
T, °C
τ, min
0
60
2
1
50 100 150 200 250 300 350 400 450 500 550 600 650 700 750 800 850 900 950 T, °C
10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 τ, min
0
5
Fig. 5. TG, DTG, and DSC curves for (1) compound 2 and (2) [Cu(НL) ⋅ 2Н О].
2
2
absorption bands, which belong to the stretching
vibrations of ОН and NHSO2 bonds and observed in
the spectra of their ligands. The vibrations of water
molecules are characterized by the bands appearing in
the spectrum of the complex at 3375–3440 cm–1 (Fig. 4,
the example for copper). Based on the obtained data,
it is possible to propose the following formula (3) for
the complexes [МL ⋅ 2Н2О]:
O
O
OH2
OH2
M
(3)
N
R
S
SO2
Table 1. Elemental composition of the NMs(II) complexes with 2-tosylamino-4,5,6,7-tetrahydrobenzo[b]thiophene-3-
carboxylic acid (2, H2L)
Content of elements, wt %
Molecular
weight
Complex
calcd., %
N
found, %
N
C
H
S
M(II)
C
Н
S
M(II)
8.31*
[Cu(НL)2 ⋅ 2Н2О]
[СuL ⋅ 2Н2О]
[NiL ⋅ 2Н2О]
800.45
449.00
444.17
444.39
48.02
42.80
43.27
43.25
4.53
4.26
4.31
4.30
3.50
3.12
3.15
3.15
16.02
14.28
7.94 48.20
4.24
4.03
4.15
3.89
3.55
3.50
3.22
3.14
15.46
14.15 39.88
12.19 14.53*
11.9 16.50*
10.89 14.00*
14.43 13.22
14.43 13.26
41.67
41.27
[CoL ⋅ 2Н2О]
* According to thermal analysis data.
RUSSIAN JOURNAL OF INORGANIC CHEMISTRY Vol. 63 No. 7 2018

992
MANYLOVA et al.
Table 2. –logSP for complexes of 3-substituted-2-(aryl-,
methyl)sulfonylamino-4,5,6,7-tetrahydrobenzo[b]thiophenes
with Cu(II) ions (P = 0.95; n = 3–4)
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Translated by E. Glushachenkova
RUSSIAN JOURNAL OF INORGANIC CHEMISTRY
Vol. 63
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2018