Synthesis and spectral characteristics of Ni(II) 1-aryl-3-aryl(alkyl)-5- (benzothiazole-2-yl)formazanates

Article abstract of DOI:10.1134/S1070328408090054

Novel mono-and binuclear metal complexes of Ni(II) based on 1-aryl-3-aryl(alkyl)-5-(benzothiazole-2-yl)formazanes were synthesized and their structures were studied by the electronic and IR spectroscopy, mass spectrometry and megnetochemical methods.

Full text of DOI:10.1134/S1070328408090054

ISSN 1070-3284, Russian Journal of Coordination Chemistry, 2008, Vol. 34, No. 9, pp. 659–663. © Pleiades Publishing, Ltd., 2008.
Original Russian Text © Z.G. Rezinskikh, I.G. Pervova, G.N. Lipunova, T.I. Maslakova, Yu.A. Gorbatenko, I.N. Lipunov, G.I. Sigeikin, 2008, published in Koordinatsionnaya
Khimiya, 2008, Vol. 34, No. 9, pp. 669–673.
Synthesis and Spectral Characteristics
of Ni(II) 1-Aryl-3-Aryl(alkyl)-5-(benzothiazole-2-yl)formazanates
Z. G. Rezinskikha, I. G. Pervovaa, G. N. Lipunovab, T. I. Maslakovaa, Yu. A. Gorbatenkoa,
I. N. Lipunov, and G. I. Sigeikinc
a Ural State Forestry Engineering University, Yekaterinburg, Russia
b Ural State Technical University, Yekaterinburg, Russia
c Interdepartmental Center for Analytical Investigations, Presidium of the Russian Academy of Sciences, Moscow, Russia
E-mail: biosphera@usfeu.ru; family@k66.ru
Received September 5, 2007
Abstract—Novel mono- and binuclear metal complexes of Ni(II) based on 1-aryl-3-aryl(alkyl)-5-(benzothia-
zole-2-yl)formazanes were synthesized and their structures were studied by the electronic and IR spectroscopy,
mass spectrometry and megnetochemical methods.
DOI: 10.1134/S1070328408090054
Formazanes (azohydrazones) have been known long
Synthesis of Ni(II) 1-phenyl-3-phenyl-5-(ben-
ago as ligands for metal complexes, widely used as zothiazole-2-yl)formazanate (III). To a solution of
dyes [1, 2]. Recent years have seen the increasing inter- formazane (0.6 mmol) in 50 ml of acetone, a solution of
est in metal hetarylformazanates; in a number of pat- nickel nitrate (0.3 mmol) in a minimum amount of ace-
ents, they were present as components of the optical tone was added at 40 5°ë in drops with constant stir-
layers of recording elements [3–6]. Thus, Ni(II) 1-aryl- ring. The mixture obtained was stirred for 30 min and
3-aryl(alkyl)-5-(pyridine-2-yl)formazanates (Ä) were concentrated to a volume of 10 ml. The precipitate
studied and used as the above components [3, 4].
formed was filtered, washed with warm distilled water,
ethyl alcohol, and dried in air. Nickel(II) formazanates
IV, V, VIII, XIII were synthesized similarly.
N
Synthesis of Ni(II) 1-(2-carboxyphenyl)-3-phe-
nyl-5-(benzothiazole-2-yl)formazanate (II). To a
solution of formazane (0.6 mmol) in 50 ml of acetone,
a solution of nickel nitrate (0.6 mmol) in a minimum
amount of acetone was added at 40 5 in drops with
const stirring. The reaction mixture was stirred for 30
min and concentrated to a volume of 10 ml. The precip-
itate formed was filtered, washed with warm distilled
water, ethyl alcohol, and dried in air. Nickel(II) forma-
zanates VI, VII, XI, XII were obtained similarly.
Ni/2
N
N
N Ar
N
R
(Ä)
In the patents [5–7], the heterocyclic fragment of the
mono- and binuclear metal complexes of formazanes
covers a wide range of azaheterocycles; the metal atom
is being varied; the method and equipment for record-
ing and replay are described.
Synthesis of Ni(II) 1-(4-sulfophenyl)-3-methyl-5-
(benzothiazole-2-yl)formazanate (IX). To a solution
of formazane (0.6 mmol) in 50 ml of an aqueous etha-
nol, a solution of nickel nitrate (0.3 mmol) in 15 ml of
water was added in drops at 40 5°ë with constant stir-
ring. The mixture obtained was stirred for 30 min and
concentrated to a 10-ml volume. The precipitate formed
was filtered, washed with warm distilled water, and
dried in air.
In addition, formazane complexes containing the
donating substituents in positions 1, 3, 5 of the forma-
zane chain draw attention as the metal ligands, i.e., the
building units of the coordination polymer [8].
With the aim to design different-purpose metal com-
plexes, we synthesized Ni(II) complexes with 1-aryl-3-
alkyl-5-(benzothiazole-2-yl)formazanes (L) (I–XIII)
and studied their structures.
Synthesis of Ni(II) 1-(2-hydroxy-5-sulfophenyl)-
3-methyl-5-(benzothiazole-2-yl)formazanate (X). A
solution of nickel nitrate (0.5 mmol) in 15 ml of water
was added in drops to a solution of formazane
EXPERIMENTAL
Nickel(II) benzothiazolylformazanate (I) was syn- (0.5 mmol) in 50 ml of an aqueous ethanol at 40 5°ë
thesized by a known procedure [9]. with constant stirring. The reaction mixture was con-
659

660
REZINSKIKH et al.
Table 1. The elemental analysis of Ni(II) complexes I−XIII, their yields and melting point
R2
N
5
4
3
2
1
NH N C N N
R1
R3
S
Content (found/calcd.) %
Ligand
R1
R2
R3
Complex Yield, % Tm, °C
C
H
N
Ni
L1
L2
L3
L4
L5
L6
L7
L8
L9
C6H5
H
H
I
53
56
54
61
55
54
49
52
62
53
48
56
55
285
265
61.68/62.20 3.87/3.65
7.30/7.48
C6H5
COOH H
II
III
54.89/55.05 3.62/2.87 16.09/15.29 12.46/12.81
58.74/58.68 3.35/3.29 16.16/16.30 6.99/6.83
61.49/61.61 4.25/4.43 19.54/19.60 7.07/6.88
57.93/58.04 4.21/4.59 19.40/19.91 8.72/8.34
48.68/48.87 2.97/3.39 15.36/15.14 13.14/13.35
46.36/46.28 3.23/3.21 19.54/19.06 13.00/13.30
55.80/55.66 4.93/4.68 22.53/22.92 8.33/8.00
44.28/44.61 3.07/3.00 16.90/17.35 6.78/7.27
C6H5
H
H
H
4-COOH
260
C6H5
4-N(CH3)2 IV
245
CH(CH3)2
H
V
240
CH(CH3)2 COOH H
CH(CH3)2 OH 5-NO2
VI
VII
265
280
CH3
CH3
H
4-N(CH3)2 VIII
250
H
4-SO3H
5-SO3H
4-NO2
IX
X
>250
>250
>250
145
L10 CH3
L11 CH3
L12 C4H9
L13 C4H9
OH
OH
OH
H
40.30/40.20 2.40/2.48
13.05/13.10
XI
XII
44.46/44.47 3.25/3.52 18.40/18.31 13.25/12.78
48.57/47.92 4.25/4.43 17.07/16.77 11.82/11.71
59.23/58.74 5.65/5.68 20.25/20.56 7.61/7.18
4-NO2
4-N(CH3)2 XIII
270
centrated to a volume of 10 ml. The precipitate obtained
was washed with warm distilled water and dried in air.
RESULTS AND DISCUSSION.
Two series of benzothiazolylformazanes (L) were
used in the synthesis of Ni(II) coordination compounds.
The first series contains at the N1 atom of the aryl frag-
ment the 4-COOH, 4-N(CH3)2, 4-SO3H groups capable
of forming the additional coordination bonds, whereas
the second series contains the groups 2-COOH, 2-OH
participating in the formation of the metal chelate unit
(Table 1).
The analysis for C, H, and N was performed on a
PE2400SII analyzer (Perkin Elmer); nickel was deter-
mined by the gravimetry method.
IR spectra of ligands L2, L3, L6, L7, L11, L12, and their
complexes with Ni(II) were recorded on a Specord
75IR spectrophotometer at 400−4000 cm–1 (with KBr
pellets and Nujol suspension). The electronic absorp-
tion spectra were measured on a UV-5200 spectropho-
tometer (Beckman) at 350–800 nm.
Thus, benzothiazolylformazanes of the first series
(L1, L3–5, L8, L9, and L13) were used to obtain Ni(II)
complexes with the participation of only the chelate
group of the initial ligand. As follows from the elemen-
tal analysis data, benzothiazolylformazanates I, III−V,
VIII, IX, XIII synthesized on the basis of the above
benzothiazolylformazanates have the composition
NiL2. The electronic spectra of these complexes contain
one absorption maximum at 620−675 nm (Table 2).
The absorption band ν(NH) at 3500−3200 cm–1 is
lacking from the IR spectra of the above compounds,
which indicates the involvement of the NH group in the
complex formation process. Besides, in the IR spec-
trum of formazanate III, the band ν(ëé) is retained in
the same region as in the initial ligand
The magnetic characteristics of compounds V, VII,
VIII, XIII were measured on a Quantum Du-sign 5-XL
magnetometer at 0–300 K and 30 and 50 kOe magnetic
field strength.
Mass spectra of nickel formazanates were recorded
on a Shimadzu LCMS-2010 liquid chromatomass spec-
trometer using the atmospheric-pressure chemical ion-
ization (APCI) method with recording of the positive
and negative ions. The samples were introduced to the
mass spectrometer through the chromatograph with the
SPD-M10Avp diode matrix using the method of direct
injection to the ionic source.
RUSSIAN JOURNAL OF COORDINATION CHEMISTRY Vol. 34 No. 9 2008

SYNTHESIS AND SPECTRAL CHARACTERISTICS
661
Table 2. The electronic spectroscopy and mass spectrometry data for Ni(II) complexes I–XIII
m/z (I, %)
Complex
Empirical formula
C40H28N10S2Ni
λmax, nm
found
calculated
I
620
771(100)
917(5)
771.59
916.28
859.61
II
C42H26N10S2O4Ni2
C42H28N10S2O4Ni
550, 1080, 1200
645
III
IV
V
859(29)
C44H38N12S2Ni
670
C34H32N10S2Ni
600
VI
VII
VIII
IX
X
C36H30N10S2O4Ni2 · 2H2O
C34H28N12S2O6Ni2
C34H34N12S2Ni
540, 1080, 1200
540; 675
670
847(28)
881(1)
848.26
882.24
C30H24N10S4O6Ni · H2O
C15H11N5S2O4Ni
630
545; 660
565; 720
570; 710
675
445(100)
825(10)
909(9)
448.12
826.12
910.3
XI
XII
XIII
C30H20N12S2O6Ni2 · 2C2H5OH
C36H32N12S2O6Ni2 · 2C2H5OH
C40H45N12S2Ni
(1700−1690 cm−1) (Table 3), i.e., the COOH group ML2 with the MN6 coordination core or ML with the
does not participate in the complex formation.
MN3O coordination core.
The elemental analysis data indicate that Ni(II) ben-
zothiazolylformazanates II, VI, VII, XI, XII synthe-
sized from the above ligands have the composition
Ni2L2. The electronic absorption spectra of the
1-(2-carboxyphenyl)-containing complexes II, VI con-
tain absorption maxima at 540−550 nm and in the near-
IR region (at 1080 and 1200 nm). According to the lit-
erature data, the latter bands indicate the planar struc-
ture of these complexes [11]. At the same time, the
absorption spectra of metal complexes VII, XI, XII
based on 1-(2-hydroxyphenyl)-containing formazanes
exhibit, in addition to the absorption at 540–570 nm,
the second band at 675−720 nm (Table 2).
The disappearance of a high-frequency band ν(ëé)
at 1700−1690 cm–1 and its shift toward low frequencies
(1640 cm–1) in IR spectra of complexes II, VI (Table 3)
points to the involvement of the carboxyl group to the
complexation process.
Note that the absorption band appears at 1680 cm–1
in the IR spectrum of the 1-(2-hydroxy-5-nitrophenyl)-
containing formazane L7 that is shifted toward low-fre-
The magnetic moments (meff) of complexes V, VIII,
XIII measured at T = 295 K lie in the interval
2.68−2.85 µB (for V, VIII, and XIII, µeff = 2.68, 2.72,
and 2.85 µB, respectively), which agrees with the liter-
ature data [9] and suggests the octahedral structure of
the above metal complexes.
The composition NiL2 was confirmed also by mass
spectra using compounds I, III as examples (Table 2).
Previously [10], the structure of the analogous com-
plexes was studied by X-ray diffraction, for example,
Ni(II) 1-butylphenyl-3-butyl-5-(benzothiazole-2-yl)for-
mazanate. The metal was found to be coordinated through
the N1 and N4 atoms of the formazane chain and the N
atom of the benzothiazole fragment with the formation of
pseudo-octahedron with the NiN6 coordination core.
Benzothiazolylformazanes L1, L3–5, L8, L9, and L13
are supposed to be coordinated to the Ni2+ ions to give
the analogous structure (B):
R3
Ni/2
N
Table 3. IR spectra of Ni(II) complexes
N
N
N
Complex
ν(CO)
ν(Ni–N) [ν(Ni–O)]
N
C
S
R1
II
1640
1690
1640
1650
1660
460
III
VI
VII
XI
XII
460
(B)
470
The compounds L2, L6, L7, L11, and L12 containing in
the aryl fragment of the formazane chain the 2-OH,
2-COOH groups are the tetradentate ligands and can
give complexes of two types with different structures:
480
500
480 [640]
RUSSIAN JOURNAL OF COORDINATION CHEMISTRY Vol. 34 No. 9 2008

662
χ × 106, cm3 g–1
REZINSKIKH et al.
Based on the above-indicated spectra data, the struc-
ture of Ni(II) formazanates II, VI, VII, XI, XII can be
presented as a binuclear dimer (C), by the analogy with
a nickel complex based on 1-(2-carboxyphenyl)-3-iso-
propyl-5-(benzimidazole-2-yl)formazane, whose struc-
ture was established by X-ray diffraction [15].
16
14
12
10
8
R1
C
N
N
S
N
N
N
Ni
6
R3
X
4
R3
X
2
Ni
N
C
N
N
0
N
S
N
50
100
150
200
250
300
T, K
R1
–2
X = O, COO
(C)
The temperature dependence of the magnetic susceptibility
of nickel formazanate VII.
According to the elemental analysis data, nickel
benzothiazolylformazanate X obtained from 1-(2-
hydroxy-5-sulfophenyl)-containing formazane has the
composition NiL. The electronic absorption spectrum
of this compound shows two absorption bands at 545
and 660 nm, similarly to Ni(II) 1-(2-hydroxy-5-nitro-
phenyl)formazanate VII (Table 2).
quency region in its nickel complex VII and can be
assigned to ν(ëé) of the ligand quinoid fragment. In
the case of 1-(2-hydroxy-4-nitrophenyl)-substituted
analogs, the band at 1660 cm–1 appears only in the IR
spectrum of complex XI. The analogous situation was
observed for the previously described 1-(2-hydroxy-
4,5-nitrophenyl)-substituted formazanes and their com-
plexes [12]. Thus, in all the above cases, the shift of the
band ν(ëé) in the IR spectra indicates the participation
of this group in the coordination with a central metal
atom (Table 3).
The IR spectrum of compound X does not exhibit
the bands ν(NH) and ν(éH) of the initial ligand, which
suggests that both groups containing the labile hydro-
gen atom take part in the complex formation process.
In mass spectrum of the above compound, the most
intense peak corresponds to a molecule ion of the com-
position NiL (Table 2).
In accordance with the data [13], we assigned the
absorption bands at 460−500 cm–1 in the IR spectra of
metal complexes II, VI, VII, XI, and XII to the stretch-
ing vibrations of the Ni-N bonds. The absorption band
at 640 cm–1, which appears in the IR spectrum of com-
pound XII but is absent from the spectrum of the corre-
sponding ligand, was assigned to the stretching vibra-
tion of the Ni-O bond [13], which suggests the involve-
ment of the O atom in binding of the metal ion
(Table 3).
On the basis of the above data, one can assume that
complex X has the structure D, containing the MN3O
coordination core, as in the case of copper(II) benzothi-
azolylformazanate [16]:
SO3H
Metal chelate VII was studied by the static magnetic
susceptibility method, and its effective magnetic
moment was found to be 0.63 µB (T = 295 K), which
suggests the coordination core structure close to the
square. The study of the temperature dependence of the
magnetic susceptibility showed that starting from
T = 150 K, the magnetic susceptibility increases (see in
the figure). The analogous behavior was observed pre-
viously for Ni(II) 1-(o-carboxyphenyl-5-benzozaylfor-
mazanates [14].
O
N
Ni
N
N
S
C
N
N
CH3
(D)
The study of the spectral parameters of the synthe-
sized metal complexes that differ in the chemical com-
position of the initial ligand showed that both mono-
The peaks due to the molecular ions corresponding and binuclear complexes can be obtained, depending
to the composition Ni2L2 (Table 2) are observed in mass on the nature of substituents R1, R2, R3 of the formazane
spectra of compounds II, VI, VII, XI, XII.
molecule.
RUSSIAN JOURNAL OF COORDINATION CHEMISTRY Vol. 34 No. 9 2008

SYNTHESIS AND SPECTRAL CHARACTERISTICS
663
8. Frolova, N.A., Vatsadze, S.Z., Zavodnik, V.E., et al., Izv.
Akad. Nauk, Ser. Khim., 2006, no. 10, p. 1745.
9. Lipunova, G.N., Krylov, E.I., Bednyagina, N.P., and
Sharov, V.A., Zh. Obshch. Khim., 1969, vol. 39, no. 6,
p. 1293.
ACKNOWLEDGMENTS
This work was supported by the Russian Foundation
for Basic Research (project nos. 06-03-08040ofi and
07-03-12050ofi).
10. Shmelev, L.V., Lipunova, G.N., Kessenikh, A.V., et al.,
Koord. Khim., 1993, vol. 19, no. 3, p. 215.
REFERENCES
11. Drago, R.S., Physical Methods in Chemistry, Philadel-
1. Buzykin, B.I., Lipunova, G.N., Sysoeva, L.P., and Rusi-
nova, L.P., Khimiya formazanov (The Chemistry of For-
mazans), Moscow: Nauka, 1992.
2. Sigeikin, G.I., Lipunova, G.N., and Pervova, I.G., Usp.
Khim., 2006, vol. 75, no. 10, p. 980.
3. Chapman, D.D., Pat.Eur.Appl., 837.457; 22.04.1998.
4. Chapman, D.D., Pat.Eur.Appl., 837.462; 22.04.1998.
5. Aizawa, Y., Kawata, T., and Yasui, S., Pat.Eur.Appl.,
1.347.030; 24.09.2003.
6. Noguchi, S. and Sato, T., Pat.Eur.Appl., 1.335.357;
13.08.2003.
7. Tomura, T., Sato, T., Ueno, Y., and Noguchi, S., US
Patent, 2006, p. 23.
phia: Saunders, 1977, vol. 2.
12. Krivonogova, T.I., Lipunova, G.N., Garnovskii, A.D.,
et al., Zh. Obshch. Khim., 1988, vol. 58, no. 1, p. 184.
13. Nakomoto, K., Infrared and Raman Spectra of Inorganic
and Coordination Compounds, New York: Wiley, 1986.
14. Validuda, G.I., Lipunova, G.N., Garnovskii, A.D., et al.,
Zh. Obshch. Khim., 1986, vol. 56, no. 4, p. 827.
15. Rezinskikh, Z.G., Slepukhin, P.A., Lipunova, G.N.,
et al., Koord. Khim., 2008, vol. 34, no. 9, p. 663 [Russ. J.
Coord. Chem. (Engl. Transl.), vol. 34, no. 9, p. 653].
16. Vishnevskaya, G.P., Frolova, E.N., Pervova, I.G., et al.,
Koord. Khim., 2005, vol. 31, no. 11, p. 828 [Russ. J.
Coord. Chem. (Engl. Transl.), vol. 31, no. 11, p. 828].
RUSSIAN JOURNAL OF COORDINATION CHEMISTRY Vol. 34 No. 9 2008