The synthesis and Ni(II), Co(II), Cu(II), Cd(II), and Zn(II) complexes of two new unsymmetrical vic-dioximes

Full text of DOI:10.1081/SIM-100106855

SYNTH. REACT. INORG. MET.-ORG. CHEM., 31(7), 1163–1174 (2001)
THE SYNTHESIS AND Ni(II), Co(II), Cu(II),
Cd(II), AND Zn(II) COMPLEXES OF TWO
NEW UNSYMMETRICAL
vic-DIOXIMES
Emine Ozcan,*,1 Emin Karapinar,2
and Nazan Karapinar3
1Selcuk University, Faculty of Arts and Sciences,
Chemistry Department, 42031 Konya, Turkey
E-mail: emineozcan@hotmail.com
2Pamukkale University, Faculty of Arts and Sciences,
Chemistry Department, 20020 Denizli, Turkey
E-mail: eminkarapinar@hotmail.com
3Pamukkale University, Engineering Faculty, Chemistry
Engineering Department, 20020 Denizli, Turkey
ABSTRACT
Two new substituted aminoglyoximes, N-(4-ethylphenyl)-
amino-amphi-glyoxime [L1H2] and N-(4-ethylphenyl)amino-
anti-glyoxime [L2H2], have been synthesized from amphi-
chloroglyoxime and anti-chloroglyoxime and 4-ethylanilin.
The preparation of nickel(II), cobalt(II), copper(II), zinc(II)
and cadmium(II) complexes of the amphi- and anti-isomers
of these ligands are described. All of these complexes are
insoluble in common solvents. IR spectra and elemental
*Corresponding author.
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Copyright # 2001 by Marcel Dekker, Inc.
www.dekker.com

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analyses data of these complexes are given. Also, mass and
1H NMR spectra of these ligands are presented.
INTRODUCTION
The transition metal complexes of vic-dioximes have been of particular
interest as biological model compounds173. Most of the work carried out so
far has been on symmetrically disubstituted glyoximes476 and partly on
monosubstituted ones779. The substitution pattern of the vic-dioxime moiety
affects the stability of the complexes; e.g., Co(II) complexes of dialkyl- or
diarylglyoximes and dithioglyoximes can be obtained by the reduction of
octahedral Co(III) compounds6710, but the complexes decompose in the
case of diaminoglyoxime derivatives4.
In the present paper, we report the synthesis and complex formation
of two new substituted aminoglyoximes of unsymmetrically substituted
vic-dioximes. The asymmetry of the ligands is also expected to enhance
the solubility of planar complexes derived from them.
RESULTS AND DISCUSSION
Two new aromatic aminoglyoxime derivatives were synthesized by
reacting aromatic amines with amphi-chloroglyoxime17,18 or anti-chlor-
oglyoxime17,18, respectively. The structure of these ligands were identified by
employing elemental analyses, 1H NMR spectroscopy, IR spectroscopy and
mass spectroscopy (Tables I, II, III and IV, respectively). The metal com-
plexes were identified by elemental analyses and IR spectroscopy (Tables I
and III, respectively). The formation and general formulas of the synthe-
sized ligands are shown in Fig. 1.
1H NMR Spectra of Ligands
1
In the H NMR spectrum of L1H2, two peaks are present for the OH
protons of the oxime groups (Table II). These two deuterium-exchangeable
singlets correspond to two non-equivalent OH protons which also indicate
the anti-configuration of the OH groups relative to each other274,679,11,12
.
When the chemical shift values of the two OH groups of L1H2 are com-
pared, the value for the one at lower field is 12.45 ppm and for the one at

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COMPLEXES OF vic-DIOXIMES
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COMPLEXES OF vic-DIOXIMES
1169
Figure 1. General formulas of ligands.
higher field is 12.25 ppm (Table II). The first one is assigned to the OH
proton on the phenyl side and the latter to the OH proton of the amidoxime
group, since the effect of various substituents is expected to be higher on the
amidoxime group. In L1H2, the N-H proton is observed at 4.60 ppm.
Addition of D2O caused the disappearance of the NH and OH peaks for
L1H2 and L2H2. A triplet at 1.10 ppm and 1.09 ppm corresponds to the CH3
protons for L1H2 and L2H2, respectively. Due to the low solubility of L2H2
in organic solvents, the 1H NMR spectra of L2H2 were obtained in D2O and
only protons bonded to carbon were observed (Table II).
IR Spectra of Ligands and Complexes
In the IR spectra of the ligands, NH (332073640 cmÀ1), OH
(328073380 cmÀ1), C›N- (154071620 cmÀ1) and NO (9057910 cmÀ1
)
stretches appear at frequencies expected for substituted aminoglyoximes4,7,8
(Table III).
The IR spectra of the complexes of L2H2 support structures 2(a) as
well as 2(b) in Fig. 2 by the weak bending vibration of the O-H O bridges
around 173571750 cmÀ1 and the shift of the C›N vibration to lower fre-
quencies at 154071620 cmÀ1 due to N,N-metal coordination4,7,8,13,14. In the
case of the Zn(II) anti-form complex, the coordinated H2O molecules are
identified by a broad OH absorption around 3380 cmÀ1 which keeps its
intensity even after heating in an oven at 110 ꢀC for 24 h.
L1H2 reacts with metal salts to give 1:1 metal-ligand ratio complexes
with two of the four coordination sites on the metal occupied by the N atom

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Figure 2. Octahedral and square-planar metal complexes of the unsymmetrical
ligands.

COMPLEXES OF vic-DIOXIMES
1171
of one of the oxime group and the O atom of the other, respectively. Two
water molecule are also coordinated to the metal ion in [LH(H2O)2M]
(Fig. 2c). The elemental analyses results and IR spectra are consistent with
such a structure8,15,16
.
Mass Spectra of Ligands
The mass spectra of the ligands also support their structures
(Table IV). The molecular ion peak is 207.3which indicates the formula
weight of both ligands. Both ligands give similar mass spectra. For example,
the first fragment ion is OH and last one is phenyl.
EXPERIMENTAL
amphi- and anti-Chloroglyoxime were prepared according to published
methods17,18. All reagents were purchased from Merck (Germany) or Fluka
(Switzerland), and were used without further purification. Melting points
were determined on an Electrothermal IA 9100 digital melting point
apparatus and are uncorrected. The elemental analyses (C, H, and N) have
1
been determined by using a Carlo-Erba 1106 model analyzer. H NMR
spectra were recorded on a Bruker 200 MHz spectrometer, IR spectra on a
Jasco FT=IR-300e instrument using KBr pellets. The pH was measured on a
WTW pH.537 pH meter. Mass spectra were obtained in the research
laboratories of TUBITAK (Center of Sciences and Technology Research of
Turkey).
Synthesis of Substituted Diaminoglyoximes (L1H2 and L2H2)
A quantity of 1.250 mL (0.010 mol) freshly distilled 4-ethylanilin
(r ¼ 0:970 g:cmÀ3) dissolved in 15 mL diethyl ether was added dropwise to a
stirred solution of 1.225 g(0.010 mol) amphi-chloroglyoxime dissolved in
15 mL diethyl ether or anti-chloroglyoxime dissolved in 15 mL ethanol. The
pH of the resultant solution was increased from 3.073.5 to 4.575.0 by
adding a solution of KOH in ethanol. The resulting white crystalline pre-
cipitate was filtered, washed with petroleum ether and dried in vacuo.
L1H2: Yield, 1.37 g. This compound is soluble in water, ethanol,
CHCl3, DMSO, DMF and dioxan and insoluble in CCl4. Table II shows the
1H NMR data of this ligand.

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L2H2: Yield, 0.45 g. This compound is soluble in water, slightly soluble
1
in DMSO, DMF and CCl4 and insoluble in CHCl3. Table II shows the H
NMR data of this ligand.
The colors, formula weights, yields, melting points, elemental analy-
tical results, IR, mass spectra data of these ligands are given Tables I, III
and IV, respectively.
Synthesis of the Ni(II), Co(II), and Cd(II) Complexes L1H2
A solution of 0.005 mol metal salt [NiCl2Á6H2O (1.189 g), CoCl2Á6H2O
(1.190 g), CdCl2Á2H2O (1.097 g), CuCl2Á2H2O (0.852 g)] dissolved in 30 mL
water was added to a stirred solution of 1.035 g (0.005 mol) of ligand dis-
solved in 30 mL of a 1:1 ethanol-water mixture. For the copper complex the
ligand was dissolved in 30 mL diethyl ether. On addition of the metal salt, the
pH dropped from 4.575.0 at the beginning of the reaction to 3.574.0. The
pH was raised to 6 by the addition of a solution of KOH in ethanol. The
complex started to precipitate by adding water and the mixture was placed
in a water bath at 50755 ꢀC for 15720 min until precipitation was complete.
The precipitated complex was filtered, washed with water and dried at
60 ꢀC. The colors, formula weights, yields, melting points, elemental ana-
lytical results and IR spectral data of the compounds are given in
Tables I and III.
Synthesis of the Ni(II), Cu(II), Co(II), and Zn(II) Complexes of L2H2
When a solution of 0.005 mol metal salt [NiCl2Á6H2O (1.189 g),
CuCl2Á2H2O (0.852 g), CoCl2Á6H2O (1.190 g), ZnCl2Á2H2O (0.861 g)] in
30 mL water was added to a solution of the ligand L2H2 (0.01 mol, 2.07 g)
dissolved in 30 mL of ethanol, the pH of the mixture dropped to 3.073.5
and its color turned to red-black. By the addition of a 1% NaOH
solution in water the pH was increased to 5.576.0 and the mixture was
stirred on a water bath at 50755 ꢀC for 15720 min. The precipitated
complexes were filtered while hot, washed with water and dried at 100 ꢀC.
The colors, formula weights, yields, melting points, elemental analytical
results and IR spectral data of the compounds are given in Tables I
and III, respectively.

COMPLEXES OF vic-DIOXIMES
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Received May 14, 1998
Accepted May 18, 2001
Referee I: T. J. McNeese
Referee II: R. A. Faltynek