Synthesis, Characterization, and Thermal Investigation of Copper(II), Nickel(II), Cobalt(II), and Zinc(II) Complexes with 5-Benzoyl-1- (phenylmethylenamino)-4-phenyl-1H-pyrimidine-2-thione

Article abstract of DOI:10.1081/SIM-120025448

Cu(II), Ni(II), Co(II) and Zn(II) complexes of 5-benzoyl-1-(phenyl- methylenamino)-4-phenyl-1H-pyrimidine-2-thione were prepared. These complexes have been characterized by elemental analyses, IR, NMR and UV-Vis spectra. Spectral studies, magnetic moment

Full text of DOI:10.1081/SIM-120025448

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Synthesis and Reactivity in Inorganic and Metal-Organic
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Synthesis, Characterization and Thermal
Investigation of Copper(II), Nickel(II),
Cobalt(II) and Zinc(II) Complexes with
5‐Benzoyl‐1‐(phenylmethylenamino)‐4‐phenyl‐1H‐pyrimidin
Mehmet Sönmeza a & Memet Şekercib b
a Department of Chemistry, Faculty of Science and Arts, Yüzüncü Yıl, University, Van, 65080,
Turkey
b Department of Chemistry, Faculty of Science and Arts, Fırat University, 23169,
Elazı[gcheck], Turkey
Version of record first published: 15 Feb 2007.
To cite this article: Mehmet Sönmeza & Memet Şekercib (2003): Synthesis, Characterization
and Thermal Investigation of Copper(II), Nickel(II), Cobalt(II) and Zinc(II) Complexes with
5‐Benzoyl‐1‐(phenylmethylenamino)‐4‐phenyl‐1H‐pyrimidine‐2‐thione, Synthesis and Reactivity in Inorganic and Metal-Organic
Chemistry, 33:9, 1689-1700
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SYNTHESIS AND REACTIVITY IN INORGANIC AND METAL-ORGANIC CHEMISTRY
Vol. 33, No. 9, pp. 1689–1700, 2003
Synthesis, Characterization, and Thermal
Investigation of Copper(II), Nickel(II),
Cobalt(II), and Zinc(II) Complexes with
5-Benzoyl-1-(phenylmethylenamino)-4-
phenyl-1H-pyrimidine-2-thione
2
Mehmet So¨nmez1, and Memet S¸ekerci
*
1Department of Chemistry, Faculty of Science and Arts,
Yu¨zu¨ncu¨ Yıl University, Van, Turkey
2Department of Chemistry, Faculty of Science and Arts,
ꢀ
Fırat University, Elazıg, Turkey
ABSTRACT
Cu(II), Ni(II), Co(II) and Zn(II) complexes of 5-benzoyl-1-(phenyl-
methylenamino)-4-phenyl-1H-pyrimidine-2-thione were prepared. These
complexes have been characterized by elemental analyses, IR, NMR
and UV-Vis spectra. Spectral studies, magnetic moment and molar
conductivity measurements were performed on these compounds. All of
the complexes are non-electrolytes. The metal complexes are proposed
*
Correspondence: Mehmet So¨nmez, Department of Chemistry, Faculty of Science
and Arts, Yu¨zu¨ncu¨ Yıl University, 65080 Van, Turkey; E-mail: vansonmez@hotmail.
com.
1689
DOI: 10.1081/SIM-120025448
0094-5714 (Print); 1532-2440 (Online)
www.dekker.com
Copyright D 2003 by Marcel Dekker, Inc.

1690
So¨nmez and S¸ekerci
to have an octahedral structure. Thermal studies of the complexes are
also reported.
Key Words: Pyrimidine-2-thione; Metal complexes.
INTRODUCTION
In recent years, heterocyclic Schiff bases containing NS and NSO
donor atoms and their 3d metal complexes have attracted considerable
attention due to their remarkable antifungal, antibacterial and antitumor
activity.[1,2] The majority of papers of some authors contain the results of
spectroscopic and magnetic studies of coordination compounds of hete-
rocyclic[3–5] derivatives in the solid state. Transition metal compounds with
pyrimidine derivatives included in nucleic acids, such as uracyl, cytosine
and thymine were also of special interest.
We recently reported the synthesis and characterization of hetero-
cyclic complexes obtained from N-aminopyrimidine-2-one with salicyl-
aldehyde[6,7] (Figure 1). In this paper we report the preparation, charac-
terization and thermal investigation of new Cu(II), Ni(II), Co(II) and
Zn(II) metal complexes.
EXPERIMENTAL
Materials and Methods
MeOH, EtOH, CHCl3, DMF, toluene, diethylethere, n-heptane,
thiosemicarbazide and benzaldehyde were obtained from Fluka or Aldrich
Chemical Co. The metal salts Cu(AcO)2ꢀH2O, Co(AcO)2ꢀ4H2O, Zn-
(AcO)2ꢀ2H2O and NiCl2ꢀ6H2O were obtained from E. Merck Chemical
Co. All solvents were distilled before use.
Figure 1. Structure of the ligand.

Complexes of Pyrimidine-2-thiones
1691
Elemental analyses (C, H, N) were performed by using a Carlo Erba
1106 elemental analyzer. The IR spectra were obtained using KBr discs
(4000–400 cm–1) on a Bio–Rad–Win–IR spectrophotometer. The
electronic spectra in the 200–900 nm range were obtained in DMF on a
Unicam UV2-100 UV/Visible spectrophotometer. Magnetic measurements
were carried out by the Gouy method using Hg[Co(SCN)4] as calibrant.
Molar conductances of the Schiff base ligand and their transition metal
complexes were determined in DMF at room temperature using a Jenway
1
model 4070 conductivity meter. The H NMR spectra of the Schiff base
was recorded with a Varian XL-200 NMR instrument. TGA measurements
were carried out by a Shimadzu-50 thermal analyzer.
Synthesis of the Ligand
The Schiff base ligand (5-benzoyl-1-(phenylmethylenamino)-4-phenyl-
1H-pyrimidine-2-thione) was synthesized according to the literature
method.[8] The ligand was prepared by the reaction of the 5-benzoyl-4-
phenyl-2,3-furandion (1 mmole, 0.395 g) and benzaldehydethiosemicarba-
zone (1 mmole, 0.180 g) in dry toluene (40 mL), by boiling the mixture
under reflux for 1.5 h. The precipitated ligand was filtered, recrystallized
from acetic acid and dried in a vacuum dessicator, mp 185°C. Anal. Found:
C, 72.70; H, 4.36; N, 10.65; S, 7.81; calc. for C24H17N3OS (MW 395.5): C,
72.89; H, 4.33; N, 10.63; S, 8.11 %. Yield; 0.140 g, 36%.
Synthesis of the Complexes
The complexes were prepared by adding a methanolic solution (15
mL) of the metal salt (0.02 mole of copper or zinc salt or 0.01 mole of
cobalt or nickel salt, respectively) to the solution of 0.02 mole of the
ligand in chloroform (30 mL). The precipitated complexes were filtered,
washed with water, n-heptan, followed by cold methanol and dried in a
vacuum dessicator.
RESULTS AND DISCUSSION
All of the synthesized complexes are colored solids. The compounds
are stable at room temperature and in air, soluble in DMSO and DMF, but
poorly soluble in methanol and ethanol. The elemental analyses and thermal
analyses are in agreement with the chemical formulas of the compounds.

1692
So¨nmez and S¸ekerci
The reactions of the Schiff base ligand with the corresponding metal
salt can be represented as follows:
methanol=chloroform
2L þ MðAcOÞ2 ꢀ nH2O
½MðLÞ2ðAcOÞ2ꢁ ꢀ mH2O þ xH2O
M = Cu(II), Co(II), Zn(II)
L = C24H17N3OS
n =
m =
x =
1
1
–
4
–
4
2
–
2
methanol=chloroform
2L þ NiCl2 ꢀ 6H2O
½NiðLÞ2Cl2ꢁ þ 6H2O
The metal-to-ligand ratio of the bidentate Co(II), Cu(II), Zn(II) and
Ni(II) complexes was found to be 1:2, in addition to the two acetate/
chloride ligands. The Cu(II) complex has one additional water of water of
crystallization (Table 1).
IR spectra
The infrared values of the complexes studied are presented in Table 2.
The IR spectrum of the ligand shows three strong bands at 1650 n(C = O),
1035 n(C= S) and 1600 cm–1 n(C =N) azomethine vibrations.[6–8] The
strong and broad absorption in the region 3440 cm–1 of the Cu(II) complex
substantiates the presence of a water molecule.[13] The band at 1600 cm–1,
due to the stretching mode of the azomethine group in the spectrum of the
free ligand, shows a remarkable negative shift with splitting in the 1565
cm–1 region in all of the complexes spectra suggesting that the coordinating
azomethine nitrogen atom of the Schiff base is involved in the complexes
formation. The band at 1035 cm–1 may be attributed to the predominant
n(C= S) stretching mode in most of this ligand. The decrease of ꢂ 30 cm–1
in the frequency of this band in the complexes suggests the coordination of
sulfur of the C =S (thione) moiety. On the other hand, the IR spectra of the
Co(II), Cu(II) and Zn(II) complexes confirm that the acetate group which
may be assigned to AcO anion at ~1415 cm–1 is coordinated.[13] New bands
observed in the complexes at 445–476 cm–1 and 410–425 cm–1 are
tentatively assigned to the n(M–N)[6,7,13] and n(M–S) vibrations.[13]
Electronic Spectra
The electronic absorption spectral data for the complexes, that are
dissolved in DMF, are shown in Table 2. In the spectrum of the Schiff base,

Complexes of Pyrimidine-2-thiones
1693

1694
So¨nmez and S¸ekerci

Complexes of Pyrimidine-2-thiones
1695
the bands of 300–400 nm are attributed to the azomethine chromophor and
benzenoid p ! p* and n ! p* transitions.
The six coordinated Cu(II) complex is expected to be tetragonal and is
confirmed by the characteristic absorption at 660 nm, assignable to
2
2T2g ! Eg transition. The magnetic moment of this complex is 1.72 BM at
room temperature.
The spectrum of the Ni(II) complex is consistent with octahedral
geometry showing two d–d transition bands at 660 and 542 nm assignable
3
3
3
3
to transitions A2g ! T1g(F) and A2g ! T2g(F) respectively which
suggests octahedral geometry. The magnetic moment values for the Ni(II)
complex of the Schiff base ligand at room temperature were found to be in
the normal range (2.8–3.8 B.M.).[14] [Ni(LH2)2Cl2]ꢀ2H2O showed magnetic
moment value of 5.96 BM. The high moments for the Ni(II) complex have
been ascribed to quite strong ferromagnetic exchange.
The magnetic moment value for the [Co(L)2(AcO)2] complex of the
ligand is near the spin only value for high spin octahedral complexes. The
electronic spectrum shows two bands at 763 and 594 nm attributed to
4
4
4
4T1g ! A2g (n2) and T1g(F) ! T1g(P) (n3) transitions respectively, in an
octahedral geometry around the Co(II) ion.[14]
The electronic spectra of the Zn(II) complex, which is diamagnetic,
has bands in the 395–322 nm range and these bands may be due to the
n ! p* and p ! p* transitions of the benzene, pyrimidine rings and azo-
methine group.
1H NMR Spectra
Deuterated chloroform and deuterated DMSO were used to measure the
1H NMR spectra of the ligand[8] and its Zn(II) complex, respectively, except
those of Cu(II), Co(II) and Ni(II) because of their paramagnetic behavior.
The singlets at d 9.0 ppm and 8.9 ppm are due to the azomethine proton of
pyrimidine ring (C–H) proton in the spectrum of the ligand, respectively. In
the spectra of the Schiff base the phenyl multiple was observed between d
7.3–8.0 ppm.[8] The 1H NMR spectrum of the Zn(II) complex shows
approximately the same peaks identical to those of the free ligand.
Conductivity
All of the complexes are non-electrolytes as shown by their molar
conductivity (LM) in DMF, and which are in the range[9–12] 2.1–12.3 O–1
cm2 mol–1.

1696
So¨nmez and S¸ekerci
Thermal Studies
The thermal stability of the complexes was investigated using TGA.
The TGA curves were obtained at a heating rate of 10°C/min. in N2
atmosphere over the temperature range of 25–850.0°C.
The Cu(II) complex was stable up to 30.0°C. Its decomposition started
at this temperature and was completed at 692.0°C. The Cu(II) complex
decomposed and produced CuO as residue [found (calculated) %: 8.30
(8.04)] in four steps in the temperature ranges 30.0–115.0, 115.0–199.0,
199.0–205.0 and 205.0–692.0°C. In the decomposition process of the
Cu(II) complex, the mass losses corresponded to H2O, CH3COO, Ph–CH–
and the other organic moieties leaving in the first, second, third and fourth
stages of the decomposition, respectively. The four stages of the de-
composition of the Cu(II) complex were irreversible.
The Co(II) complex was stable up to 119.0°C. Its decomposition started
at this temperature and was completed at 626.0°C. The Co(II) complex
decomposed and produced CoO as residue [found (calculated) %: 5.81
(7.75)] in three steps in the temperature ranges 119.0–199.8, 199.8–292.0
and 292.0–626.0°C. In the decomposition process of the Co(II) complex,
the mass losses corresponded to CH3COO, Ph–CH– and the other organic
moieties leaving in the first, second and third stages of the decomposition,
respectively. The three stages of the decomposition of the Co(II) complex
were irreversible.
The Ni(II) complex was stable up to 112.0°C. Its decomposition started
at this temperature and was completed at 631.6°C. The Ni(II) complex
decomposed and produced NiO as residue [found (calculated) %: 7.50
(8.12)] in two steps in the temperature ranges 112.0–210.0 and 210.0–
631.6°C. In the decomposition process of the Ni(II) complex, the mass
losses corresponded to Ph–CH– and Cl and the other organic moieties
leaving in the first and second stages of the decomposition, respectively.
The two stages of decomposition of the Ni(II) complex were irreversible.
The Zn(II) complex was stable up to 172.0°C. Its decomposition started
at this temperature and was completed at 629.0°C. The Zn(II) complex
decomposed and produced ZnO as residue [found (calculated) %: 8.72
(8.36] in two steps in the temperature ranges 172.0–215.0 and 215.0–
629.0°C. In the decomposition process of the Zn(II) complex, the mass
losses corresponded to Ph–CH– and the other organic moieties leaving in
the first and second stages of the decomposition, respectively. The two
stages of decomposition of the Zn(II) complex were irreversible.
The Cu(II) complex is thermally stable up to 30.0°C, whereas the
Ni(II), Co(II), and Zn(II) complexes are thermally stable up to 112.0°C,
119.0°C, and 172.0°C, respectively. In the TGA curve of the Cu(II)

Complexes of Pyrimidine-2-thiones
1697

1698
So¨nmez and S¸ekerci
Figure 2. Proposed structure for all the complexes.
complex, 1.83% weight loss was observed at 115.0°C. This shows that
the complex contains 1 mole of water of crystallization per complex mole-
cule. The IR spectra of the complexes show a broad band in the region
3230–3650 cm–1 due to the n(O–H) frequency of water of crystalliza-
tion.[6,13] This water content was also identified by elemental analyses. The
decomposition process of the Cu(II), Ni(II), Co(II) and Zn(II) complexes
was also confirmed by TGA data. As can be seen in Table 3, the most
stable complex is the Zn(II) complex.
The weight losses for the Cu(II), Ni(II), Co(II) and Zn(II) complexes
were found to be approximately the same, when expressed as the
percentages calculated stoichiometrically from their chemical formulas
given in Tables 1, 3 and 4. All of these complexes undergo complete
decomposition to the corresponding metal oxides, CuO, NiO, CoO or
ZnO[6,15–18] (Table 3).
Single crystals of the complexes could not be isolated from any
solutions, thus no definitive structure could be described. However, the
analytical, spectroscopic and magnetic data enable us to propose the
possible structures as shown in Figure 2.
ACKNOWLEDGMENT
We thank the Research Fund of the Yu¨zu¨ncu¨ Yıl University for
fınancial support.

Complexes of Pyrimidine-2-thiones
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Received November 2, 2002
Accepted June 5, 2003
Referee I: X. Zhou
Referee II: M. Kalafatis