Coordination compounds of 3d-metal 5-sulfosalicylates with thiosemicarbazide

Article abstract of DOI:10.1134/S107036321301009X

Copper(II), nickel(II), and cobalt(III) 5-sulfosalicylate complexes with thiosemicarbazide were synthesized and characterized by elemental analyses, IR spectra, diffuse reflectance spectra, and thermo-gravimetric data.

Full text of DOI:10.1134/S107036321301009X

ISSN 1070-3632, Russian Journal of General Chemistry, 2013, Vol. 83, No. 1, pp. 54–57. © Pleiades Publishing, Ltd., 2013.
Original Russian Text © T.V. Koksharova, S.V. Kurando, I.V. Stoyanova, 2013, published in Zhurnal Obshchei Khimii, 2013, Vol. 83, No. 1, pp. 60–64.
Coordination Compounds of 3d-Metal 5-Sulfosalicylates
with Thiosemicarbazide
T. V. Koksharovaa, S. V. Kurandoa, and I. V. Stoyanovab
a Mechnikov Odessa National University, ul. Dvoryanskaya 2, Odessa, 65026 Ukraine
e-mail: koksharova@farlep.net
b Bogatskii Physicochemical Institute, National Academy of Sciences of Ukraine, Odessa, Ukraine
Received December 5, 2011
Abstract—Copper(II), nickel(II), and cobalt(III) 5-sulfosalicylate complexes with thiosemicarbazide were
synthesized and characterized by elemental analyses, IR spectra, diffuse reflectance spectra, and thermo-
gravimetric data.
DOI: 10.1134/S107036321301009X
5-Sulfosalicylic acid and its anions are charac-
terized by structural diversity and interesting topology.
In recent time, 5-sulfosalicylate ions and their metal
complexes attract increasing attention due to their
antimicrobial, antifungal, and anti-inflammatory
activity. 5-Sulfosalicylic acid molecule possesses three
functional groups, SO3H, COOH, and OH. Five forms
of 5-sulfosalicylic acid were distinguished [1]:
(1) neutral, (2) singly deprotonated at the sulfo group,
(3) singly deprotonated at the carboxy group,
(4) doubly deprotonated at the sulfo and carboxy
groups, and (5) triply (completely) deprotonated.
Reactions of partially or completely deprotonated
forms of 5-sulfosalicylic acid (H2SSal–, HSSal2–, and
SSal3–) with metal ions may lead to different coor-
dination modes [1].
According to the elemental analysis data (Table 1),
copper(II) and nickel(II) 5-sulfosalicylates reacted
with thiosemicarbazide to form 1:2 complexes,
whereas cobalt(III) 5-sulfosalicylate gave rise to 1:3
complex. It should be noted that we obtained two
isomeric Ni(II) complexes. Prolonged reaction of
nickel(II) 5-sulfosalicylate with an equimolar amount
of thiosemicarbazide afforded green complex II,
whereas pink complex III was rapidly formed in the
reaction of nickel(II) 5-sulfosalicylate with 2 equiv of
thiosemicarbazide. We failed to isolated coordination
compound in the reaction of zinc(II) 5-sulfosalicylate
with thiosemicarbazide.
Unlike initial thiosemicarbazide, the thioamide I
absorption band in the IR spectra of all isolated
complexes was observed at higher frequency with
some reduction in intensity (Table 2). High-frequency
shift was also observed for the thioamide II band. The
thioamide III band weakened so strongly that we
detected it only in the spectrum of complex I, while it
was indistinguishable in the spectra of the other
complexes. The frequency of the thioamide IV band
decreased. In keeping with published data [3] the
observed variation of thioamide absorption pattern
corresponds to bidentate coordination of thiosemi-
carbazide through the sulfur and nitrogen atoms.
We previously [2] synthesized and studied coor-
dination of compounds of 3d-metal salicylates with
thiosemicarbazide. It was interesting to find out how
introduction of a sulfo group into salicylate ion affects
the composition, structure, and properties of the
resulting 3d-metal complexes with thiosemicarbazide.
Thus the goal of the present work was to synthesize
coordination compounds of cobalt(III), nickel(II),
copper(II), and zinc(II) 5-sulfosalicylates with thio-
semicarbazide and examine their properties. The
targeted complexes were synthesized by reaction of
thiosemicarbazide with an aqueous solution of pre-
liminarily prepared 3d-metal 5-sulfosalicylate at metal-
to-thiosemicarbazide ratios of 1:1 and 1:2.
Absorption bands corresponding to vibrations of 5-
sulfosalicylate anion were assigned with account taken
of the data in [1, 4–6]. The carbonyl stretching
vibration frequency ν(C=O) in the spectra of all
complexes was lower by no more than 18 cm–1 relative
54

COORDINATION COMPOUNDS OF 3d-METAL 5-SULFOSALICYLATES
55
Table 1. Elemental analyses of coordination compounds I–IV formed by 3d-metal 5-sulfosalicylates and thiosemicarbazide
Found, %
N
Calculated, %
Comp.
no.
Color
Formula
M
S
M
N
S
Dark violet
Green
9.3
8.9
8.9
6.3
12.3
18.7
18.8
18.9
19.3
C16H20CuN6O12S4
C16H20N6NiO12S4
C16H20N6NiO12S4
C24H30CoN9O18S6
9.4
8.7
8.7
6.0
12.4
12.4
12.4
12.8
18.8
19.0
19.0
19.5
I
12.1
II
Pink
12.3
III
IV
Brown
12.5
Table 2. Absorption bands (cm–1) in the IR spectra of thiosemicarbazide (HL), 5-sulfosalicylic acid (H3SSal), and coordina-
tion compounds I–IV
Assignment
ν(NH)
HL
H3SSal
I
II
III
IV
3370, 3260,
3170
3371, 3306,
3248, 3178
3352, 3309,
3175
3356, 3306,
3175
ν(C=O)
1678
1670
1562
1666
1574
1666
1574
1660
1585
Thioamide I
1530
1315
ν(C=Carom
)
1477, 1439
1477, 1435
1393, 1369
1477, 1423
1370
1477, 1435
1373
1477, 1435
1377
Thioamide II
νas(SO2)
1234, 1203,
1165, 1134 sh
1215, 1184,
1155, 1126
1223, 1188,
1146, 1122
1219, 1146,
1122
1211, 1180,
1157, 1126
νs(SO2)
1084, 1065,
1026
1084, 1030
1080, 1018
1080, 1018
1084, 1030
Thioamide III
Thioamide IV
ν(S–O)
1000
800
975 w
706
–
–
–
706
663
706
667
720
667
663
667
to ν(C=O) of free 5-sulfosalicylic acid. Proton ab-
stracttion from the carboxy group should lead to
disappearance of carbonyl absorption band and
appearance of two new bands at considerably lower
frequencies due to antisymmetric and symmetric
vibrations of carboxylate group (COO–) where two
oxygen atoms are equivalent [7]. The observed pattern
suggests that the COOH group remained un-ionized. In
all cases, insignificant variations in the absorption
pattern of aromatic C=C bonds were detected.
Absorption bands of sulfo groups revealed appreciable
changes. The νas(SO2) frequency decreased by 8–
23 cm–1 in going from free 5-sulfosalicylic acid to the
coordination compounds. The IR spectra of all
complexes contained two νs(SO2) bands against three
bands for free 5-sulfosalicylic acid. This may be due to
higher symmetry of the sulfo group as a result of its
deprotonation. Thus the IR spectra indicated that the 5-
sulfosalicylate ion in the synthesized complexes is
singly deprotonated at the sulfo group.
It should be noted that isomeric nickel complexes
[Ni(HL)2](H2SSal)2 (II and III) displayed almost
identical IR spectra. A few differences included lower
frequency of one ν(C=C) band in the spectrum of
green complex II and the lack of one νas(SO2) band in
the spectrum of pink complex III. Identical
compositions and similar IR spectra led us to presume
that nickel(II) 5-sulfosalicylate complexes with
thiosemicarbazide are conformational isomers. It is
known [8] that just nickel(II) complexes could give
rise to conformational isomerism square planar–
tetrahedral and that square planar complexes are
generally colored red to yellow, while tetrahedral,
green to blue. The diffuse reflectance spectra (Table 3)
confirmed the square planar structure of the pink
complex and tetrahedral structure of the green
complex. In keeping with the diffuse reflectance
spectra, the cobalt(III) complex has a distorted
octahedral configuration of the coordination entity [9].
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56
KOKSHAROVA et al.
Table 3. Diffuse reflectance spectra of coordination com-
pounds I–IV
Table 4. Thermogravimetric analysis of coordination com-
pounds I–IV
Comp. no.
ν, cm–1
14860 br
16730
4400
Assignment
Overall
Endo-effect
Exo-effect
Comp.
no.
weight
loss, %
I
T, °C
Δm, %
T, °C
Δm, %
3T1 → 3T1(P)
3T1 → 3A2
ν1
II
220–300
(250)
39.3
80.0
I
32810
17510
III
IV
300–500
(330)
17.2
1A1g → 1A2
500–600
(590)
13.3
4.8
The structure of complex I was confirmed by X-ray
analysis. The centrosymmetric [Cu(HL)2]2+ square in
complex I is supplemented with Cu–O bonds
(2.810 Å) with the sulfonate fragment to form a tetra-
gonal bipyramid. The Cu–O bonds together with
hydrogen bonds give rise to a supermolecule. Cations
are arranged in layers alternating with anion layers [10].
600–700
(650)
300–370
(330)
46.6
400–480
(460)
8.0
83.8
85.0
77.5
II
550–650
(570)
16.1
9.5
The results of thermogravimetric analysis of
complexes I–IV (Table 4) showed the absence of
endo-thermic effects for Cu(II) and Co(III) complexes
230–280
(250)
–
380–490
(420)
III
IV
280–380
(310)
46.0
540–640
(550)
13.0
27.8
21.9
I
and IV, unlike analogous complexes with
unsubstituted salicylate. Obviously, this is related to a
catalytic effect of Cu(II) and Co(III) on the combustion
process. Isomeric nickel(II) complexes II and III
displayed just endothermic effects first. The first endo-
effect for pink complex III was observed at 250°C
almost without weight loss. The other effects on the
thermogravimetric curves of nickel(II) complexes II
and III were essentially similar in both temperatures
230–280
(250)
480–610
(530)
and amounts of lost weights. These findings suggest
that the first endo-effect without weight lost
OH
NH2
H2
N
S
C
HN
C
_O
O
M
NH
S
N
S
O
H2
H2N
H2N
O
OH
2
M = Cu (I), Ni (II, III).
H
N
NH2
NH2
OH
OH
S
S
_O
Co
S
O
NH
S
N
H2N
HN
H2
O
O
3
NH2
IV
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COORDINATION COMPOUNDS OF 3d-METAL 5-SULFOSALICYLATES
57
corresponds to the isomerization of the square planar
complex into tetrahedral.
Complexes II and IV (general procedure). Nickel(II)
or cobalt(III) chloride, 0.02 mol, was dissolved in 5 ml
of water, a solution of 0.8 g (0.02 mol) of NaOH in
5 ml of water was added, the precipitate of metal
hydroxide was filtered off, washed with water, and
added in portions to a solution of 4.36 g (0.02 mol) of
5-sulfosalicylic acid in 5 ml of water, and 0.02 (II) or
0.04 mol (IV) of dry finely powdered thiosemicar-
bazide was added in small portions to the resulting
solution. The mixture was left to stand for 3 days in a
porcelain dish, and the precipitate was filtered off,
washed with water, and dried at 50°C until constant
weight.
Thus we assigned the following structures to coor-
dination compounds I–IV.
Comparison of our results with the data for
analogous complexes derived from unsubstituted Sali-
cylates shows the following. 5-Sulfosalicylate anion
provides the possibility for conformational isomerism
of Ni(II) coordination polyhedron. Cobalt(III) gives
Co(HL)L2(HSal) complexes with unsubstituted Sali-
cylate and Co(HL)3(H2SSal)3 complexes with 5-sulfo-
salycilate, i.e., in the former case the complexation
process involves partial deprotonation of thiosemi-
carbazide. If there is a sulfo group, proton is abstracted
just from it, whereas the carboxy group remains un-
ionized, in contrast to unsubstituted salicylate.
Thiosemicarbazide complexes with 3d-metal 5-sulfo-
salicylates are characterized by considerably higher
thermal stability, presumably due to much stronger
bonds of the central ion with anions, on the one hand,
and more potent hydrogen bond system, on the other.
REFERENCES
1. Sai-Rong Fan and Long-Guan Zhu, J. Mol. Struct.,
2007, vol. 827, nos. 1–3, p. 188.
2. Koksharova, T.V., Kurando, S.V., and Stoyanova, I.V.,
Russ. J. Gen. Chem., 2012, vol. 82, no. 9, p. 1481.
3. Singh, B., Singh, R., Chaudhary, R.V., and Thakur, K.P.,
Indian J. Chem., 1973, vol. 11, no. 2, p. 174.
4. Gordon, A.J. and Ford, R.A., The Chemist’s Companion,
New York: Wiley, 1972.
EXPERIMENTAL
5. Nothenberg, M.S., de Souza, A.R., and Matos, J.R.,
Polyhedron, 2000, vol. 19, no. 11, p. 1305.
The IR spectra were recorded on a Shimadzu FTIR-
8400S spectrometer from samples prepared as KBr
pellets. The diffuse reflectance spectra were measured
on a Perkin–Elmer Lambda-9 instrument against MgO
(βMgO = 100%). Thermogravimetric analysis was per-
formed on a Paulik–Paulik–Erdey derivatograph in air;
samples were heated at a rate of 10 deg/min.
6. Nakanishi, K., Infrared Absorption Spectroscopy.
Practical, San Francisco: Holden-Day, 1962. Translated
under the title Infrakrasnye spektry
i
stroenie
organicheskikh soedinenii, Moscow: Mir, 1965, p. 67.
7. Kukushkin,
Yu.N.,
Khimiya
koordinatsionnykh
soedinenii (Chemistry of Coordination Compounds),
Moscow: Vysshaya Shkola, 1985, p. 180.
8. Greenwood, N.N. and Earnshaw, A., Chemistry of the
Elements, Oxford: Butterworth–Heinemann, 1997, 2nd ed.
Translated under the title Khimiya elementov, Moscow:
BINOM, Laboratoriya znanii, 2008, vol. 2, p. 483.
9. Lever, E., Inorganic Electronic Spectroscopy, Amster-
dam: Elsevier, 1984, 2nd ed.
10. Koksharova, T.V., Antsyshkina, A.S., Sadikov, G.G.,
Sergienko, V.S., and Kurando, S.V., Abstracts of Papers,
XXV Mezhdunarodnaya Chugaevskaya konferentsiya po
koordinatsionnoi khimii i II Molodezhnaya shkola-
konferentsiya “Fiziko-khimicheskie metody v khimii
koordinatsionnykh soedinenii” (XXVth Int. Chugaev
Conf. on Coordination Chemistry and IInd Youth
School–Conf. “Physicochemical Methods in the Chem-
istry of Coordination Compounds”), Suzdal’, 2011, p. 140.
11. Schwarzenbach, G. and Flaschka, H., Die komplexo-
metrische Titration, Stuttgart: Ferdinand Enke, 1965.
Cobalt(II), nickel(II), copper(II), and zinc(II) chlo-
rides, 5-sulfosalicylic acid, and thiosemicarbazide of
analytical grade were used. The metal content of the
isolated complexes was determined by complexo-
metric tetration [11], nitrogen was determined by the
Dumas method [12], and sulfur was determined by the
Shöniger oxidation [12].
Complexes I and III (general procedure). Copper
(II) or nickel(II) chloride, 0.01 mol, was dissolved in
5 ml of water, a solution of 0.4 g (0.01 mol) of NaOH
in 5 ml of water was added, the precipitate of metal
hydroxide was filtered off, washed with water, and
added in portions to a solution of 2.18 g (0.01 mol) of
5-sulfosalicylic acid in 5 ml of water, and 1.82 g
(0.02 mol) of dry finely powdered thiosemicarbazide
was added in small portions to the resulting solution.
The mixture was stirred for 15 min on a magnetic
stirrer, and the precipitate was filtered off, washed with
water, and dried at 50°C until constant weight.
12. Klimova, V.A., Osnovnye mikrometody analiza orga-
nicheskikh soedinenii (Principal Micro-methods for
Analysis of Organic Compounds), Moscow: Khimiya,
1975.
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