A new cyclobutane-substituted schiff base ligand and its Co(II), Cu(II), Ni(II), and Zn(II) complexes

Article abstract of DOI:10.1081/SIM-100002045

A new ligand, 4-(1-phenyl-1-methylcyclobutyl-3-yl)-2-(2-hydroxy-1-naphtylidene)thiazole (LH), has been synthesized starting from 1-phenyl-1-methyl-3-(2-chloro-1-oxoethyl) cyclobutane, thiourea and 2-hydroxy-1-napthalaldehyde. Mononuclear complexes with a metal-ligand ratio of 1:2 have been prepared with Co(II), Cu(II), Ni(II) and Zn(II) salts. Structures of the ligand and its complexes are suggested based on elemental analyses, IR, ¹³C and ¹H NMR spectra, magnetic susceptibility measurements and thermogravimetric analyses (TGA).

Full text of DOI:10.1081/SIM-100002045

Synthesis and Reactivity in Inorganic and Metal-Organic
Chemistry
ISSN: 0094-5714 (Print) 1532-2440 (Online) Journal homepage: http://www.tandfonline.com/loi/lsrt19
A NEW CYCLOBUTANE-SUBSTITUTED SCHIFF BASE
LIGAND AND ITS Co(II), Cu(II), Ni(II), AND Zn(II)
COMPLEXES
Alaaddin Çukurovali , Ibrahim Yilmaz , Misir Ahmedzade & Habibe Özmen
To cite this article: Alaaddin Çukurovali , Ibrahim Yilmaz , Misir Ahmedzade & Habibe Özmen
(2001) A NEW CYCLOBUTANE-SUBSTITUTED SCHIFF BASE LIGAND AND ITS Co(II), Cu(II), Ni(II),
AND Zn(II) COMPLEXES, Synthesis and Reactivity in Inorganic and Metal-Organic Chemistry,
31:2, 255-262, DOI: 10.1081/SIM-100002045
To link to this article: http://dx.doi.org/10.1081/SIM-100002045
Published online: 15 Feb 2007.
Submit your article to this journal
Article views: 29
View related articles
Citing articles: 2 View citing articles
Full Terms & Conditions of access and use can be found at
http://www.tandfonline.com/action/journalInformation?journalCode=lsrt19
Download by: [University of Nebraska, Lincoln]
Date: 19 December 2015, At: 13:35

SYNTH. REACT. INORG. MET.-ORG. CHEM., 31(2), 255–262 (2001)
A NEW CYCLOBUTANE-SUBSTITUTED
SCHIFF BASE LIGAND AND ITS Co(II),
Cu(II), Ni(II), AND Zn(II) COMPLEXES
Alaaddin C¸ ukurovali,∗ Ibrahim Yilmaz,
¨
Misir Ahmedzade, and Habibe Ozmen
Firat University, Faculty of Arts and Sciences, Chemistry
Department 23119 Elazig˘, Turkey
ABSTRACT
Anewligand, 4-(1-phenyl-1-methylcyclobutyl-3-yl)-2-(2-hydroxy-
1-naphtylidene)thiazole (LH), has been synthesized starting from
1-phenyl-1-methyl-3-(2-chloro-1-oxoethyl) cyclobutane, thiourea
and 2-hydroxy-1-napthalaldehyde. Mononuclear complexes with a
metal-ligand ratio of 1 : 2 have been prepared with Co(II), Cu(II),
Ni(II) and Zn(II) salts. Structures of the ligand and its complexes are
suggested based on elemental analyses, IR, 13C and 1H NMR spec-
tra, magnetic susceptibility measurements and thermogravimetric
analyses (TGA).
INTRODUCTION
Schiff bases and their transition metal complexes have been extensively
investigated since these types of molecules are important in chemistry. Thiazole
and its derivatives have biological significance, e.g. it is found in the vitamin
∗Address correspondence to Alaaddin C¸ ukusovali. E-mail: acukurovali@firat.edu.tr
255
Copyright ꢀ 2001 by Marcel Dekker, Inc.
www.dekker.com
C

ORDER
REPRINTS
256
C¸ UKUROVALI ET AL.
22
21
16
19
17
15
14
20
HO
10
9
N
H3C
11
18
8
6
1
N
CH
12
13
S
7
2
3
4
5
Figure 1. 4-(1-Phenyl-1-methylcyclobutyl-3-yl)-2-(2-hydroxy-1-naphtylidene)thiazole
(LH).
B1 molecule and in the coenzyme cocarboxylase 1. The penicillin molecule also
contains a thiazolidine ring. 2-Aminothiazoles are known mainly as biologically
active compounds with a broad range of activities and as intermediates in the
synthesis of antibiotics and dyes 2.
Itiswellknownthat3-substitutedcyclobutanecarboxylicacidderivativesex-
hibit anti-inflamatory and antidepressant activities (3,4), and liquid crystal
properties (5). Various thiazole derivatives show herbicidal (6), anti-inflamatory
(7,8), antimicrobial (9) or antiparasitic activity (10). However, the synthesis and
physiochemical properties of substituted thiazoles and their Schiff base derivatives
have not been reported. These compounds containing cyclobutane, thiazole and
Schiff base functions should be suitable candidates for further chemical modifica-
tions and may be pharmacologically active.
The ligand used in this work has the three different and important moieties
of cyclobutane, thiazole and Schiff base. The extensive synthetic possibilities of
this heterocycle due to the presence of several reaction sites hold promise for the
preparation of new thiazole derivatives.
Since this ligand does not exist in the literature, this paper deals with the
preparation and characterization of the complexes formed between this Schiff base
ligand (see Fig. 1) and cobalt(II), copper(II), nickel(II) and zinc(II) metal salts.
RESULTS AND DISCUSSION
Synthesis and Characterization of the Ligand
The reaction steps for the synthesis of LH are given in Figure 2. The
first step is the synthesis of (1) from the reaction of 1-phenyl-1-methyl-3-(2-
chloro-1-oxoethyl)cyclobutane and thiourea. In the second step, 2-hydroxy-1-
naphtalaldehyde and 4-(1-phenyl-1-methyl-3-cyclobutyl)-2-aminothiazole were

ORDER
REPRINTS
NEW SCHIFF BASE LIGAND
257
reacted to obtain 4-(1-phenyl-1-methylcyclobutyl-3-yl)-2-(2-hydroxy-1-naphtyli-
dene)thiazole (2) (abbreviated as LH). When necessary, column chromatography
was used to purify the compounds. The analyses showed that the substances were
of sufficient purity to conduct this type of a study.
For the structural characterization of (1) and (2), IR, 1H NMR and 13C NMR
were used and the data are given in the experimental section. Additional analytical
data are tabulated in Tables I and II.
In the IR spectrum of (1)−th1e most characteristic a−bs1orptions are at 3285 and
3310 cm−1 υ( NH2), 1604 cm υ(C N) and 685 cm υ(C S C). Since there
–
==
– –
–
==
are no C Cl and C O bands in the IR spectra, these peaks indicate the forma-
1
tion of the expected compound. The detailed H NMR and 13C NMR peaks are
given in the experimental section. In the IR spectra of (2) the most characteris-
==
==
tic absorptions are at 3464 υ(OH), 1576 υ(C N in thiazole ring), 1625 υ(C N
– –
azometine) and 657 υ(C S C thiazole). As can be seen in the IR data of (2), the
OH of the substance is not hydrogen bonded. If not, the OH absorption of the
substance would have appeared as a broad band. Characteristic 1H NMR and 13
C
NMR peaks are given in the experimental section. In the 1H NMR spectra of (2),
the OH peak is at 13.64 ppm and this peak disappeared upon the addition of D2O.
The data of (1) and (2) obtained from elemental analyses, IR, 1H NMR and 13
C
NMR are consistent with data expected from the formulas shown in Figures 1
and 2.
(1)
C
O
NH2
C
C2H5OH
N
+
H3C
H3C
H2C
NH2
S
Cl
NH2
S
HO
HO
CH
C2H5OH
N
(1)
+
OHC
H3C
N
S
Figure 2. Scheme of the preparation of the ligand, LH.

ORDER
REPRINTS
258
C¸ UKUROVALI ET AL.
Table I. The Colors, Formulas, Formula Weights, Melting Points, Yields, and Elemental
Analyses Results of the Ligand and the Complexes
Elemental Analyses
% Calculated (Found)
F.W.
g/mole Color
M.p. Yield
Compound
◦C
%
C
H
N
S
C14H16NS (1)
244.36 White
174
65
68.82
6.60
11.46
13.12
(68.60) (6.37) (11.09) (12.85)
75.35 5.56 7.03 8.05
(75.11) (5.48) (7.17) (8.25)
70.33 4.96 6.56 7.51
(69.85) (4.73) (6.11) (7.33)
69.95 4.93 6.53 7.47
(69.79) (4.63) (6.13) (7.04)
70.34 4.96 6.56 7.51
(69.89) (4.68) (6.23) (7.36)
69.80 4.92 6.51 7.45
(69.47) (4.76) (6.19) (7.16)
Ligand (2)
C25H22N2OS
Co(L)2
C50H42N4O2S2Co 853.98 Brown
Cu(L)2 Dark
C50H42N4O2S2Cu 858.59 Brown
Ni(L)2 Brick
C50H42N4O2S2Ni 853.75 Red
Zn(L)2
C50H42N4O2S2Zn 860.44 Orange
light
398.53 Brown
154
189
205
127
179
75
80
84
84
67
Metal Complexes of LH
The ligand LH, on interaction with Co(II), Cu(II) Ni(II) and Zn(II) salts,
yields complexes corresponding to the general formula M(L)2. The analytical data
for all these complexes are presented in Tables I and II.
The metal to ligand ratio of the Co(II), Cu(II) Ni(II) and Zn(II) complexes
was found to be 1:2. The infrared band observed at 1625 cm−1 which is assigned
==
to the υ(C N azometine) frequency in the free ligand is shifted to lower fre-
==
quencies after complexation. The shift of the C N vibration to lower frequency
Table II. Characteristic IR Bands (cm−1) of the Ligand and Complexes as KBr Pellets
==
C N
==
C N
– –
C S C µeff
–
–
–
NH2
Compound O H
C O Thiazole Azometine
Thiazole (B.M.)
(1)
–
–
1604 s
–
3285 and 3310 s 657 m
–
Ligand, (2) 3464 s 1295 s 1576 s
1625 vs
1604 vs
1604 vs
1604 vs
1604 vs
–
–
–
–
–
657 m
657 m
657 m
657 m
657 m
–
Co(L)2
Cu(L)2
Ni(L)2
Zn(L)2
–
–
–
–
1306 m 1576 s
1306 m 1576 s
1306 m 1576 s
1306 m 1576 s
4.13
1.68
3.25
dia
m: medium, s: strong, vs: very strong.

ORDER
REPRINTS
NEW SCHIFF BASE LIGAND
259
(1604 cm−1) is due to N-metal coordination (11). At the same time, the band ob-
served at 1295 cm−1 in the free ligand which is assigned to the υ(C O) frequency
–
is shifted to higher frequency (1306) after complexation. On the other hand, a
– ==
band not seen in (2) but present in the complexes was assigned to υ(M C N)
(12), and was observed at 848 cm−1 for the Co(II), 863 cm−1 for the Cu(II), 865
cm−1 for the Ni(II) and 860 cm−1 for the Zn(II) complexes. These indicate that
–
– ==
–
the C OH and N CH groups of the ligand are involved in complexation. The
==
– –
bands corresponding to the C N and C S C (both in thiazole ring) groups are
unchanged in the IR spectra of the complexes indicating that these groups do not
take part in complexation.
While the Zn(II) complex is diamagnetic, the Co(II), Cu(II) and Ni(II) com-
plexes are paramagnetic, and their magnetic susceptibility values are 4.13 B.M.,
1.68 B. M. and 3.25 B.M., respectively. Since the Co(II), Cu(II) and Ni(II) com-
plexes are paramagnetic, their 1H NMR spectra could not be obtained. 1H NMR
spectral data of the Zn(II) complex are given in the experimental section. As
1
can be seen in the H NMR spectra of Zn(II) complex there is no OH peak as
expected.
The metal contents were determined by flame atomic absorption spectropho-
tometer (FAAS) and the TGA curves were studied in the temperature range
20–900◦ C. The weight losses in the TGA and the metal contents as determined by
FAAS of complexes have been found to be approximately the same as the percent-
ages estimated stoichiometrically from their chemical formulas given in Table I.
All these complexes undergo complete decomposition to the corresponding metal
oxides, CuO, Co3O4, NiO or ZnO in thermal decomposition.
According to the above results, a tetrahedral geometry for the Co(II), Cu(II),
Ni(II) and Zn(II) complexes is proposed (13–16). The suggested structure of the
complexes is shown in Figure 3.
EXPERIMENTAL
2-Hydroxy-1-naphtalaldehyde and thiourea were purchased from Merck
(Pure) and used without further purification. 1-Phenyl-1-methyl–3-(2-chloro-1-
oxoethyl) cyclobutane was synthesized by the method described in the literature
(17) and purified through column chromatography prior to use.
The elemental analyses were determined on a Leco CHNSO-932 elemental
analysis apparatus. IR spectra were recorded on a Mattson 1000 FT-IR spectrom-
1
eter as KBr pellets. 13C and H NMR spectra were recorded on a Jeol FX-90Q
spectrometer. Magnetic susceptibilities were determined on a Sherwood Scientific
◦
magnetic susceptibility balance (model MK1) at room temperature (20 C) us-
ing Hg[Co(SCN)2] as a calibrant; diamagnetic corrections were calculated from
Pascal’s constants. Metal contents were determined by an Ati Unicam Model

ORDER
REPRINTS
260
C¸ UKUROVALI ET AL.
N
H3C
N
O
CH
S
M
O
N
S
CH
CH3
N
M = Co(II), Cu(II), Ni(II), Zn(II)
Figure 3. Suggested structure of the tetrahedral and square-planar complexes of the ligand
LH.
929 Atomic absorption spectrophotometer (FAAS). Thermogravimetric curves
were recorded on a Shimadzu TG-50 thermobalance.
Synthesis of 4-(1-Phenyl-1-methylcyclobutane-3-yl)-
2-aminothiazole (1)
The course of the reaction was monitored by IR spectroscopy. To a solution
of 0.76 g (10 mmole) of thiourea in 50 mL of absolute ethanol, a solution of 2.225 g
(10 mmole) of 1-phenyl-1-methyl-3-(2-chloro-1-oxoethyl)cyclobutane in 20 mL
of absolute ethanol was added dropwise at 60–70◦C with continuous stirring. By
monitoring the IR frequency of the carbonyl group of 1-phenyl-1-methyl-3-(2-
chloro-1-oxoethyl)cyclobutane the completion of the reaction was easily seen.
The solution was then made alkaline with an aqueous solution of NH3 (5%) to
separate the pale yellow 4-(1-phenyl-1-methylcyclobutane-3-yl)-2-aminothiazole
(1) from the reaction mixture. The precipitate was filtered off, washed with aque-
ous ammonia solution and water several times, dried in air and recrystallized
from aqueous ethanol (1:3). The compound was found to be soluble in methanol,
1
ethanol, CHCl3, acetone, THF, DMSO or DMF. Characteristic H NMR peaks
–
–
(CHCl3, TMS, δ ppm): 1.53 (s, 3H, CH3), 2.40 (m, 4H, CH2 cyclobutane), 3.5
–
–
(quint, d, J = 7 Hz, 1H, >CH , in cyclobutane ring), 5.99 (s, 1H,= CH in thiazole
ring), 5.44 (s, 2H, NH2), 7.14–7.39 (m, 5H, aromatic). Characteristic 13C NMR
–

ORDER
REPRINTS
NEW SCHIFF BASE LIGAND
261
peaks (CDCl3, TMS, δ ppm): 170.53 (C1), 102.56 (C2), 157.86 (C3), 32.73 (C4),
40.62 (C5), 42.43 (C6), 32.51 (C7), 130.30 (C8), 127.41 (C9), 126.96 (C10), 126.98
(C11).
Synthesis of 4-(1-Phenyl-1-methylcyclobutane-3-yl)-
2-(2-hydroxy-1-naphtylidene) thiazole (2)
To a hot (60–70◦C) solution of 2.44 g (10 mmole) of (1) in 30 mL of
absolute ethanol, a hot (60–70◦C) solution of 1.56 g (10 mmole) of 2-hydroxy-
1-napthalaldehyde in 20 mL absolute ethanol was added dropwise with contin-
uous stirring. The mixture was stirred for 1 h and left to stand overnight. The
resulting precipitate was filtered, washed several times with cold ethanol and
dried at 110◦C to constant weight. Yield, color, melting point, elemental analysis
results and characteristic IR bands (NaCl cell, cm−1) are tabulated in Tables I
and II. The compound was found to be very soluble in CHCl3, and slightly
soluble in common solvents like methanol, ethanol, acetone, THF, DMSO or DMF.
Characteristic 1H NMR peaks (CHCl3, TMS, δ ppm): 1.53 (s, 3H, CH3), 2.7–2.5 (d,
–
–
–
J = 9 Hz, 4H, CH2 in cyclobutane ring), 3.94 (m, 1H, >CH in cyclobutane ring),
==
–
6.82 (s, 1H, CH S in thiazole ring), 7.55–7.16 (m, 11H, aromatics), 7.90–7.86
(s, 1H azometine), 13.64 (s, 1H, OH). Characteristic 13C NMR peaks (CDCl3,
TMS, δ ppm): 32.01 (CH3), 161.06 (C1), 135.13 (C2), 130.27 (C3), 127.40 (C4),
127.00 (C5), 130.82 (C6), 131.31 (C7), 126.82 (C8), 129.75 (C9), 161.39 (C10),
167.01 (C11), 171.06 (C12), 111.39 (C13), 138.00 (C14), 33.14 (C15), 42.71
(C16), 40.94 (C17), 32.01 (C18), 154.16 (C19), 130.06 (C20), 124.01 (C21), 130.09
(C22).
Synthesis of the Complexes
A quantity of 0.5445 g (1.5 mmole) of the ligand was dissolved in 30–40 mL
of absolute methanol. A solution of 0.75 mmole of the metal salt [Co(OOCCH3)2·
4H2O(0.1900g), Cu(OOCCH3)2·4H2O(0.1500g), Ni(OOCCH3)2·4H2O(0.187g),
Zn(OOCCH3)2·2H2O (0.168 g)] in 20 mL of methanol was added dropwise with
continuous stirring. Every mixture was refluxed for 1 hour and left to stand
overnight. The complexes, precipitated as micro crystals, were filtered and washed
with cold ethanol and water several times and dried in vacuo at 60◦C. Yields, col-
ors, melting points, elemental analysis results and characteristic IR bands (NaCl
cell, cm−1) are given in Tables I and II. Characteristic 1H NMR peaks for the Zn(II)
–
complex (CHCl3, TMS, δ ppm): 1.63 (s, 3H, CH3), 2.5–2.7 (d, J = 9 Hz, 4H,
–
–
CH2 in cyclobutane ring), 3.84 (m, 1H, >CH in cyclobutane ring), 6.82 (s, 1H,
==
–
CH S in thiazole ring), 7.16–7.55 (m, 11H, aromatics), 9.89 (s, 1H azomethine).

ORDER
REPRINTS
262
C¸ UKUROVALI ET AL.
ACKNOWLEDGMENT
WegratefullyacknowledgethefinancialsupportofFiratUniversityResearch
¨
Fund (Project No. FUNAF-121).
REFERENCES
1. H. Beyer, “Organic Chemistry”, Verlag Harry Deutsch, Frankfurt/Main und
Zu¨rich. pp. 609-610 (1963).
2. U.G. Ibatullin, T.F. Petrushina, L.Y. Leitis, I.Z. Minibaev, and B.O. Logvin,
Khim. Geterotsikl. Soedin., 715 (1993) (USSR); Chem. Abstr., 120, 1145
(1994).
3. E. Roger, C.J. Pierre, V. Pualette, G. Gerard, J.P. Chepat, G. Robert, Eur. J.
Med. Chem., Chem-Ther., 12, 501 (1977).
4. G. Gerard, Eur. J. Med. Chem., Chem-Ther., 14, 493 (1979).
5. E.V. Dehmion, S.S. Schmidt, Liebigs Ann. Chem., 411 (1990).
6. H. Foerster, W. Hofer, V. Mues, L. Eue and R.R. Schmidt, German Patent 2,
822, 155 (1979); Chem. Abstr., 92, 146, 754 (1980).
7. S.N. Sawhney, S.K. Arora J.V. Singh, Indian J. Chem., 16B, 605 (1978);
Chem. Abstr., 90, 22879 d (1979).
8. K. Brown, D.P. Cater, J.F. Cavalla, D. Green, R.A. Newberry, and A.B.
Wilson, J. Med. Chem., 14, 177 (1974).
9. N. Suzuki, Y. Tanaka, and R. Dohmori, Chem Pharm. Bull., 27, 1 (1979).
10. P.I. Slip, M. Closier, and M. Neville, J. Med. Chem., 17, 207 (1974).
11. A. Saxena, and J.P. Tandon, Polyhedron, 3, 681 (1984)
12. N.M. Karayannis, C.M. Mikulsky, M.J. Strocko, L.L. Pytlewski, and M.M.
Labes, J. Inorg. Nucl. Chem., 32, 2629 (1970).
13. F.A. Cotton, and G. Wilkinson, “Advanced Inorganic Chemistry”, 5th Edn.,
Wiley-Interscience, pp. 725-743 (1988).
¨
14. V. Ahsen and O. Bekarog˘lu, Synth. React. Inorg. Met.-Org. Chem., 15, 61
(1985).
¨
15. Y. Go¨k and E. Ozcan, Transition Met. Chem., 16, 393 (1985).
16. N.N. Greenwood and A. Earnshaw, Chemistry of Elements, Pergamon Press,
pp. 1411-1412 (1984).
17. M.A. Ahmedov, Z.G. Mustafayeva, I.M. Ahmedov, and R.R. Kostikov, J.
Org. Chem., 27, 1434 (1991) (USSR); Chem. Abstr., 116, 807 (1992).
Received August 25, 1999
Referee I: E. K. Haub
Accepted November 14, 2000
Referee II: K. Moedritzer

Request Permission or Order Reprints Instantly!
Interested in copying and sharing this article? In most cases, U.S. Copyright
Law requires that you get permission from the article’s rightsholder before
using copyrighted content.
All information and materials found in this article, including but not limited
to text, trademarks, patents, logos, graphics and images (the "Materials"), are
the copyrighted works and other forms of intellectual property of Marcel
Dekker, Inc., or its licensors. All rights not expressly granted are reserved.
Get permission to lawfully reproduce and distribute the Materials or order
reprints quickly and painlessly. Simply click on the "Request
Permission/Reprints Here" link below and follow the instructions. Visit the
U.S. Copyright Office for information on Fair Use limitations of U.S.
copyright law. Please refer to The Association of American Publishers’
(AAP) website for guidelines on Fair Use in the Classroom.
The Materials are for your personal use only and cannot be reformatted,
reposted, resold or distributed by electronic means or otherwise without
permission from Marcel Dekker, Inc. Marcel Dekker, Inc. grants you the
limited right to display the Materials only on your personal computer or
personal wireless device, and to copy and download single copies of such
Materials provided that any copyright, trademark or other notice appearing
on such Materials is also retained by, displayed, copied or downloaded as
part of the Materials and is not removed or obscured, and provided you do
not edit, modify, alter or enhance the Materials. Please refer to our Website
User Agreement for more details.
Order now!
Reprints of this article can also be ordered at
http://www.dekker.com/servlet/product/DOI/101081SIM100002045