Complexation of ethyl 2-aryl(alkyl)sulfonylamino-4,5,6,7-tetrahydrobenzo[b]thiophene-3-carboxylates with nonferrous metal ions

Article abstract of DOI:10.1134/S003602361504004X

Complexation of sulfonyl derivatives of the Gewald thiophenes (SGT) with Cu(II), Co(II), Ni(II), Zn(II), and Cd(II) ions in ammonia solutions was studied. The molar ratio method, the Job's method of continuous variation, and coductometric titration revealed ratios [M(II)]: [SGT] = 1: 2. The composition of preparatively isolated complexes was confirmed by IR spectroscopy and elemental analysis data. Solubility product constants for precipitates of the complexes and complexation equilibrium constants were calculated. Solubility product constants for M(II) complexes was shown to be dependent on the nature of sulfonyl substituent in SGT series.

Full text of DOI:10.1134/S003602361504004X

ISSN 0036ꢀ0236, Russian Journal of Inorganic Chemistry, 2015, Vol. 60, No. 4, pp. 531–535. © Pleiades Publishing, Ltd., 2015.
Original Russian Text © L.G. Chekanova, K.O. Manylova, P.T. Pavlov, E.V. Baigacheva, T.G. Tiunova, 2015, published in Zhurnal Neorganicheskoi Khimii, 2015, Vol. 60, No. 4,
pp. 592–596.
PHYSICAL CHEMISTRY
OF SOLUTIONS
Complexation of Ethyl 2ꢀAryl(alkyl)sulfonylaminoꢀ4,5,6,7ꢀ
tetrahydrobenzo[b]thiopheneꢀ3ꢀcarboxylates
with Nonferrous Metal Ions
L. G. Chekanovaa, K. O. Manylovaa, P. T. Pavlovb,
E. V. Baigachevaa, and T. G. Tiunovaa
a Institute of Technical Chemistry, Ural Branch, Russian Academy of Sciences, ul. Koroleva 3, Perm, 614990 Russia
b Perm State University, ul. Bukireva 15, Perm, 614990 Russia
eꢀmail: larchek.07@mail.ru
Received August 11, 2014
Abstract—Complexation of sulfonyl derivatives of the Gewald thiophenes (SGT) with Cu(II), Co(II),
Ni(II), Zn(II), and Cd(II) ions in ammonia solutions was studied. The molar ratio method, the Job’s method
of continuous variation, and coductometric titration revealed ratios [M(II)] : [SGT] = 1 : 2. The composition
of preparatively isolated complexes was confirmed by IR spectroscopy and elemental analysis data. Solubility
product constants for precipitates of the complexes and complexation equilibrium constants were calculated.
Solubility product constants for M(II) complexes was shown to be dependent on the nature of sulfonyl subꢀ
stituent in SGT series.
DOI: 10.1134/S003602361504004X
Continuing interest in the chemistry of thiophene C6H4(NO2ꢀ
derivatives is associated with their both biological obtained by the reaction of initial 2ꢀaminoꢀ4,5,6,7ꢀ
activity and unique physicochemical properties [1, 2]. tetrahydrobenzo[b]thiopheneꢀ3ꢀcarboxylate ester
p) (5), C6H4(NHCOCH3ꢀp) (6), were
The application of transition metal complexes with with the corresponding sulfonyl chlorides at ambient
different thiophene derivatives is of large interest temperature in pyridine medium [6]. The individuality
[3, 4]. In this work, we report the results of study on and purity of the chemicals were confirmed by the data
1
the complexation of sulfonyl derivatives of 2ꢀamiꢀ of IR and H NMR spectroscopy, thin layer chromaꢀ
nothiopheneꢀ3ꢀcarboxylates (the Gewald thiophenes) tography, and elemental analysis.
with nonferrous metal ions. These compounds were
COOC2H5
selected because they contain electronꢀdonating
atoms that provide a possibility to form complexes
with nonferrous metal and sulfonyl group that imparts
surfaceꢀactive properties to the ligands. Several publiꢀ
cations disclosed examples of preparation and properꢀ
ties of complexes of 2ꢀaminothiopheneꢀ3ꢀcarboxylate
derivatives [5]. There are no data on the complexation
of sulfonyl derivatives of the Gewald thiophenes in the
literature.
O
(1)
R
NH
S
S
O
IR spectra were recorded on a Bruker IFSꢀ66/S
Fourierꢀtransform spectrometer (Germany), 1H NMR
spectra were obtained on a Varian MERCURY plus
300 radiospectrometer (USA) in DMSOꢀd6 solutions.
The aim of this work is to study the complexation
properties of ethyl 2ꢀaryl(alkyl)sulfonylaminoꢀ
4,5,6,7ꢀtetrahydrobenzo[b]thiopheneꢀ3ꢀcarboxylates
(SGT, HL) toward Cu(II), Co(II), Ni(II), Zn(II), and
Cd(II) ions in ammonia solutions, to determine the
composition and properties of the complexes.
Elemental analysis was performed on a LECO
CHNSꢀ932 analyzer (USA). UV spectra and optical
density were registered on a SFꢀ2000 spectrophotomꢀ
eter (Russia). pH values and solution emf were deterꢀ
mined on an ANTEKh Iꢀ160M ionometer (Belarus)
with glass and silver/silver chloride electrodes, conꢀ
ductometric titration was carried out on a Radelkis
OKꢀ102/1 conductivity meter (Hungary) with an
OKꢀ0902P electrode. Metal ion content in solutions
EXPERIMENTAL
The sulfonyl derivatives of 2ꢀaminothiopheneꢀ3ꢀ was determined on a Thermo Scientific iCE 3500
carboxylates of general formula (1), where R = CH3 ( ), atomic absorption spectrometer (USA) with flame
C6H5 ), C6H4(CH3 ), C6H4Сl
1
(
2
ꢀp)
(
3
ꢀ
p
(
4
), atomization. Thermal analysis was performed on a
531

532
CHEKANOVA et al.
S, %
100
5
1
80
4
3
60
2
40
20
0
2
4
6
8
10
12
pHeq
Fig. 1. Dependence of degree of metal ion precipitation
drobenzo[b]thiopheneꢀ3ꢀcarboxylate ( ) on solution pH , mg/L: (
) Zn(II), 53.9; ( ) Cd(II), 89.6. [M(II)] : [SGT] = 1 : 2; pH was adjusted by addition of NH OH solution.
(
S
,
%) with 2ꢀphenylsulfonylaminoꢀ4,5,6,7ꢀtetrahyꢀ
2
.
C
1
) Cu(II), 56.9; ( ) Ni(II), 47.7; ( ) Co(II), 53.3;
2
3
eq init
(4
5
4
METTLER TOLEDO TGA/DSC1 thermogravimetꢀ continuous variation for all studied M(II) ions proꢀ
ric analyzer (Switzerland).
vides ratio [M(II)] : [SGT] = 1 : 2 (Fig. 2, example for
Ni(II)). This ratio was confirmed by the molar ratio
method (Fig. 2, example for Co(II)) and conductoꢀ
metric titration.
Complexation processes were studied by precipitaꢀ
tion method as described in [7]. Extraction photometꢀ
ric procedure was used to determine the composition
of complexes of the reagents with M(II) ions by the
molar ratio method. The complexes obtained by preꢀ
cipitation were extracted with isoamyl alcohol and
optical density of the extracts was determined. The
The complexes of ethyl 2ꢀtosylaminoꢀ4,5,6,7ꢀtetꢀ
rahydrobenzo[b]thiopheneꢀ3ꢀcarboxylate (3) with all
studied metals at ratio [M(II)] : [HL] = 1 : 2 were
obtained preparatively. The obtained complexes are
insoluble in water, well soluble in ethanol, chloroform,
and isoamyl alcohol. Copper, nickel, and cobalt comꢀ
plexes are colored dark blue, green, and gray–green,
respectively; cadmium and zinc complexes are white.
The results of thermal analysis showed that the metal
treatment of saturation curve in coordinates
А = f(CR)
was performed by the known procedure [8]. The comꢀ
plexes were preparatively isolated and analyzed by
procedure [7].
complexes with compound
and undergo complete mineralization at
3
are stable up to 140
°
С
RESULTS AND DISCUSSION
T
≥
600°С.
Figure 1 shows the dependence of M(II) ions
recovery from ammonia solutions by the example of
It was established that in the coordination interacꢀ
tion with nonferrous metal ions, the studied reagents
react in ionized form as singleꢀcharged ion L–. This is
evidenced by the lack in IR spectra of characteristic
absorption bands of stretching vibrations of NH bonds
observed in the spectra of ligands (3117 cm–1). The
lowꢀfrequency shift of absorption band of the carbonyl
C=O bond in the ester fragment as compared with the
ligand indicates the formation of a donorꢀacceptor
bond with M(II) ion through the oxygen atom.
compound
2. It is seen that the reagent most comꢀ
pletely ( > 90%) precipitates metal ions in the followꢀ
ing pH range: Cu(II), 7.0–10.7; Co(II), 8.6–11.0;
Ni(II), 8.0–10.8; Zn(II), 8.2–10.5; Cd(II), 8.5–10.5.
S
The complexation of the reagents under study with
nonferrous metal ions is observed at medium pH valꢀ
ues close to their
[9] that SGT are weak acids: the
р
Ка values. It was found previously
Ка values of the
р
reagents determined by potentiometric titration are in
the range of 6.4–7.8.
On the basis of data of IR spectroscopy and eleꢀ
The ratio of components in the complexes was mental analysis (Table 1) we can suppose the following
determined by several methods. The Job’s method of formula of the isolated complexes [МL2]:
RUSSIAN JOURNAL OF INORGANIC CHEMISTRY Vol. 60 No. 4 2015

COMPLEXATION … WITH NONFERROUS METAL IONS
533
A
0.45
(а)
A
(b)
0.5
0.40
0.35
0.30
0.25
0.20
0.15
0.4
0.3
0.2
0.1
0
–log(A/(Arel – A))
0.8
0.6
IIb
0.4
Ib
0.2
0
–0.2
–0.4
–0.6
–0.8
tanα = 1.94
α
26
–logCSGT(
3
)
1 : 0.25 1 : 0.75 1 : 1.50 1 : 2.50 1 : 3.00
1 : 0.50 1 : 1.00 1 : 2.00 1 : 2.75 [Co(II)] : [SGT(
1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5
VSGT(1), mL
3
)]
Fig. 2. Determination of component ratio in complex [Ni(II)] : [SGT]: by the Job’s method of continuous variation,
V
(Ni(II)) +
–2
V(SGT(1)) = 5 mL,
C
=
C
(1
×
10 mol/L, = 410 nm, l = 1 cm (a); by the molar ratio method (Ib) (b) and curve
λ
Ni(II)
SGT(1)
–2
(Ib) treatment by equilibriumꢀshift method (IIb).
С
=
C
(1
×
10 mol/L; ammonia solution (pH 9.5),
λ
= 430 nm,
Co(II)
SGT(3)
l
= 1 cm.
The recrystallization of isolated precipitates of the
complexes is impossible owing to their decomposition
under the action of solvent (multiple washing with ethꢀ
anol and water seems to be insufficient).
CH3
OC2H5
O
SO2
S
N
(2)
The main equilibrium of M(II) complexation with
SGT in ammonia medium can be described by the
equation:
M
N
S
O
SO2
OC2H5
[M(NH3) ]2+ + 2HL
n
H3C
(3)
[ML2]↓ + 2NH+4 + (n – 2)NH3, n = 2–6.
Slightly overevaluated results of elemental analysis
for metal (Table 1) are likely to result from the adsorpꢀ
tion of hydroxo complex admixtures present in soluꢀ
tion along with ammine complexes of M(II) at pH 8–
10 (pH values at which the complexes were isolated).
Expression for solubility product (SP) of complex
precipitates is as follows:
SP = [М2+][L–]2.
(4)
Table 1. Elemental analysis data for complexes of ethyl 2ꢀtosylaminoꢀ4,5,6,7ꢀtetrahydrobenzo[b]thiopheneꢀ3ꢀcarboxylate
(HL) and its complexes with M(II)
Calculated, %
N
Found, %
N
Compound
[CuL2]
M
C
H
S
M(II)
7.74
C
H
S
M(II)
820.50 52.65
4.87
3.41
15.59
52.42
4.65
3.56
15.87
9.68
9.48*
[CoL2]
[NiL2]
814.93 53.01
814.70 53.03
4.91
4.91
3.44
3.44
15.71
15.70
7.23
7.21
56.09
53.55
5.00
5.02
3.93
3.63
16.09
14.40
7.71
8.46
8.49*
[ZnL2]
[CdL2]
822.37 52.58
869.41 49.73
4.90
4.64
3.41
3.22
15.60
14.75
7.95
53.25
45.72
4.41
4.56
3.23
3.39
15.27
14.18
8.37
12.93
13.30
12.26*
* According to thermal analysis data.
RUSSIAN JOURNAL OF INORGANIC CHEMISTRY Vol. 60 No. 4 2015

534
CHEKANOVA et al.
Table 2. Values of –logSP for complexes and equilibrium constants for complexation of M(II) ions with ethyl 2ꢀtosylꢀ
aminoꢀ4,5,6,7ꢀtetrahydrobenzo[b]thiopheneꢀ3ꢀcarboxylate (HL) in ammonia medium, CM
= C
HL = 10–3 mol/L
pptn
eq
[L–], mol/L [M2+], mol/L
S
i, %
pHeq
Keq
M
–log SP
mol/L
[M]
,
Cu
Co
Ni
98.3
99.5
99.9
99.9
99.9
1.4
3.0
5.0
2.0
7.7
×
×
×
×
×
10–5
10–8
10 –9
10–8
10–7
8.1
9.7
9.7
9.3
9.9
4.3
5.0
1.0
4.0
1.8
×
×
×
×
×
10–5
10–4
10–4
10–5
10–4
1.0
1.4
2.0
8.0
4.0
×
×
×
×
×
10–9
10–8
10–9
10–10
10–7
16.75
13.86
16.02
17.28
13.28
5.62
×
×
×
×
×
104
108
108
108
106
6.21
3.57
1.59
5.27
Zn
Cd
Table 3. Values of –logSP for complexes and equilibrium constants for the complexation of Cu(II) ions with SGT
C4H8C4SCOOC2H5NHSO2ꢀR (HL) in ammonia medium, CCu
=
C
HL = 10–3 mol/L
pptn
eq
[L–], mol/L
[M2+], mol/L
S
i, %
pHeq
R
–log SP
mol/L
,
[Cu]
CH3
99.86
99.96
98.30
99.90
97.80
99.93
1.2
3.0
1.4
8.0
1.8
6.0
×
×
×
×
×
×
10–6
10–7
10–5
10–7
10–5
10–7
9.7
9.2
8.1
9.6
7.6
8.0
1.7
1.6
4.3
3.3
3.3
1.9
×
×
×
×
×
×
10–4
10–4
10–5
10–4
10–4
10–6
1.6
6.5
4.8
1.1
6.2
2.0
×
×
×
×
×
×
10–8
10–9
10–7
10–8
10–7
10–8
16.71
18.90
16.75
17.08
14.91
16.69
C6H5
p
p
p
p
ꢀC6H4(CH3)
ꢀC6H4Ñl
ꢀC6H4NO2
ꢀC6H4NHCOCH3
The calculation of solubility product for complexes
We studied the effect of substituent at the sulfonyl
was performed similarly to that described in [10] takꢀ
ing into account ionic states of metals and ligand over
precipitate. Activity coefficients of ions were taken to
be 1 because the content of electrolytes in solution is
small. Equilibrium concentration of ligand [L–] was
calculated by the formula:
group in the series of SGT on the fraction extracted of
M(II) (example for Cu(II) ions is given in Table 3). A
satisfactory linear dependence of –logSP values of
complexes on the Hammett constants is observed for
σ
compounds 2, 4–6. This correlation for Cu(II) ions is
expressed by the equation:
Si
CuL2 : –logSР = 19.75 – 12.69σ
para
(
r
= 0.99). (7)
K CHL − 2C
М
(
)
−
100
(5)
[L ] =
,
+
Correlation equations for other M(II) ions are as
[H ]
follows:
NiL2 : –logSР = 13.46 + 3.92
where
K is the dissociation constant of ligand HL; СМ
is initial metal ion concentration, mol/L; СНL is the
initial concentration of added ligand, mol/L; Si is preꢀ
cipitation extent of metal ion in the observation point
on precipitation curve, %.
σ
(
r
= 0.96), (8)
= 0.96), (9)
= 0.99), (10)
= 0.99). (11)
para
CoL2 : –logSР = 14.43 – 7.67σ
para
(r
ZnL2 : –logSР = 13.41 – 19.34σ
para
(r
Table 2 displays the results of calculation of comꢀ
plexes SP and equilibrium constants of complexation
reactions computed by the formula (6) [11].
CdL2 : –logSР = 12.67 – 3.30
σ
(r
para
Kdiss
On the basis of obtained results, a conclusion may
be drawn that the reagents of SGT series produce
strong chelate complexes with nonferrous metal ions,
which allows one to recommend them for the proꢀ
cesses of preconcentration of nonferrous metal, for
example, by ionic flotation method.
[M(NH3)24+
]
Keq
=
(6)
.
SPМL
2
The values of equilibrium constants prove the comꢀ
pleteness of transformations (Eq. (3)). SGT form the
strongest complexes with copper, nickel, and zinc.
RUSSIAN JOURNAL OF INORGANIC CHEMISTRY Vol. 60 No. 4 2015

COMPLEXATION … WITH NONFERROUS METAL IONS
535
6. V. I. Shvedov, I. A. Kharizomenova, N. V. Medvedeva,
and A. N. Grinev, Khim. Geterotsikl. Soedin., No. 2,
204 (1977).
ACKNOWLEDGMENTS
This work was supported by the Russian Foundaꢀ
tion for Basic Research (project no. 14_03_00606_a).
7. Yu. B. El’chishcheva, L. G. Chekanova, A. V. Raduꢀ
shev, and V. I. Karmanov, Russ. J. Inorg. Chem. 55
,
1490 (2010).
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