Synthesis, characterization and extraction properties of four unsymmetricall vic-dioximes and their complexes with nickel (II), cobalt (II) and copper (II)

Article abstract of DOI:10.1080/15533170701608825

Four new unsymmetrical vic-dioximes: [L1H2] N-(4-acetanilidyl)amino-amphi- glyoxime, [L2H2] N-(4-acetanilidyl)amino-anti-glyoxime, [L3H2] N-(2-thiazolyl)amino-amphi-glyoxime and [L4H2] N-(2-thiazolyl)amino-anti- glyoxime were prepared by the reaction of amphi-chloroglyoxime and anti-chloroglyoxime with 4-aminoacetanilide and 2-aminothiazol in absolute ethanol. The preparation Ni(II), Co(II), and Cu(II) complexes of the amphi-and anti-isomers of these ligands are described.The ligands and their complexes were characterized by elemental analyses, IR, mass, H1 and 13C NMR spectra and magnetic susceptibility measurements. Ligands complexing properties were studied by the liquid-liquid extraction of selected alkali (Li+, Na+, K+, Cs+) and transition metals (Co2+, Ni2+, Cu2+, Zn2+, Cd2+, Hg2+, Pb2+). It has been observed that all ligands show a high affinity to Cu2+ and Hg2+ ions, where as almost no affinity to alkali metals. The extraction equilibrium constants (Kex) for complexes of ligands with Cu2+ and Hg2+ metal picrates between dichloromethane and water have been determined at 25C.

Full text of DOI:10.1080/15533170701608825

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Synthesis, Characterization and Extraction Properties
of Four Unsymmetricall vic‐Dioximes and their
Complexes with Nickel (II), Cobalt (II) and Copper (II)
Emin Karapinar a , Nazan Karapinar b , Emine Ozcan c & Ahmet Coskun d
a Faculty of Arts and Sciences, Department of Chemistry , Pamukkale University , Denizli,
Turkey
b Engineering Faculty, Chemistry Engineering Department , Pamukkale University , Denizli,
Turkey
c Faculty of Arts and Sciences, Department of Chemistry , Selçuk University , Konya, Turkey
d Faculty of Education, Department of Chemistry , Selçuk University , Konya, Turkey
Published online: 01 Oct 2007.
To cite this article: Emin Karapinar , Nazan Karapinar , Emine Ozcan & Ahmet Coskun (2007) Synthesis, Characterization and
Extraction Properties of Four Unsymmetricall vic‐Dioximes and their Complexes with Nickel (II), Cobalt (II) and Copper (II),
Synthesis and Reactivity in Inorganic, Metal-Organic, and Nano-Metal Chemistry, 37:8, 611-619
To link to this article: http://dx.doi.org/10.1080/15533170701608825
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Synthesis and Reactivity in Inorganic, Metal-Organic, and Nano-Metal Chemistry, 37:611–619, 2007
Copyright # 2007 Taylor & Francis Group, LLC
ISSN: 1553-3174 print/1553-3182 online
DOI: 10.1080/15533170701608825
Synthesis, Characterization and Extraction Properties of Four
Unsymmetricall vic-Dioximes and their Complexes
with Nickel (II), Cobalt (II) and Copper (II)
Emin Karapinar
Faculty of Arts and Sciences, Department of Chemistry, Pamukkale University, Denizli, Turkey
Nazan Karapinar
Engineering Faculty, Chemistry Engineering Department, Pamukkale University, Denizli, Turkey
Emine Ozcan
Faculty of Arts and Sciences, Department of Chemistry, Selc¸uk University, Konya, Turkey
Ahmet Coskun
Faculty of Education, Department of Chemistry, Selc¸uk University, Konya, Turkey
atoms, ions or molecules. Coordination compounds containing
Four new unsymmetrical vic-dioximes: [L1H2] N-(4-acetanili- vic-dioxime ligands have been known and studied from the
dyl)amino-amphi-glyoxime, [L2H2] N-(4-acetanilidyl)amino-anti-
glyoxime, [L3H2] N-(2-thiazolyl)amino-amphi-glyoxime and
[L4H2] N-(2-thiazolyl)amino-anti-glyoxime were prepared by the
reaction of amphi-chloroglyoxime and anti-chloroglyoxime with
4-aminoacetanilide and 2-aminothiazol in absolute ethanol. The
beginning of this century.[1,2] The numerous dioximes and
their transition metal complexes have been investigated.[3,4]
Since the increasing use of coordination compounds in analyti-
cal, pigment, medicinal and biochemistry, many investigators
preparation Ni(II), Co(II), and Cu(II) complexes of the amphi- have studied these topics, especially the important role of the
and anti-isomers of these ligands are described.The ligands and
their complexes were characterized by elemental analyses, IR,
complexes of 1,2-dioximes in coordination chemistry. vic-
dioximes have received considerable attention as model com-
mass, H1 and 13C NMR spectra and magnetic susceptibility
measurements. Ligands complexing properties were studied by
pounds that mimic biofunctions such as the reduction of
[3,5]
Oxime metal chelates are biologically active[6] and
the liquid-liquid extraction of selected alkali (Li1, Na1, K1,
B12
Cs1) and transition metals (Co21, Ni21, Cu21, Zn21, Cd21
,
are reported to possess semiconducting properties.[7,8] Deriva-
tives of monoaminoglyoxime, heterocyclic and macrocyclic
vic-dioximes, tetraoximes and their complexes with transition
metals have been described.[2,9–21]
Hg21, Pb21). It has been observed that all ligands show a high
affinity to Cu21 and Hg21 ions, where as almost no affinity to
alkali metals. The extraction equilibrium constants (Kex) for com-
plexes of ligands with Cu21 and Hg21 metal picrates between
dichloromethane and water have been determined at 258C.
Amines or mercaptans react with (E,E)-dichloroglyoxime or
cyanogen-di-N-oxide to yield various heterocyclic and macro-
cyclic vic-dioximes.[13,16,22–24] The (E,E)- and (E,Z)-stereoi-
somers of vic-dioximes coordinate through their N,N or N,O
sites and, in a few cases, interconversion of (E,E)- and (E,Z)-
complexes[10,25–27] is possible. Tschugaef[28] was the first to
identify the bidentate nature of vic-dioximes in his significant
work on the reaction between nickel (II) salts and dimethyl-
glyoximes. Transition metal complexes of these vic-dioximes
are essentially N,N-coordinated square-planar structures, but
the uranyl complexes form m-hydroxo-bridged dimers with
N,O-coordination as shown by infrared and 1H NMR
spectroscopy.[18,29]
Keywords liquid-liquid extractions, vic-dioximes, transition metal
complexes, alkali cations
INTRODUCTION
One of the major interests in coordination chemistry is to
study the interaction of a central atom with surrounding
Received 20 March 2007; accepted 29 April 2007.
Address correspondence to Emin Karapinar, Faculty of Arts and
Sciences, Department of Chemistry, Pamukkale University, Denizli
20017, Turkey. E-mail: ekarapinar@pau.edu.tr
Although numerous investigations have been recently
reported regarding the extraction of alkali metals and transition
611

612
E. KARAPINAR ET AL.
metals from aqueous phase into an organic phase by cold EtOH. The ligand was recrystallied from to 1:1
crown ether and calixarene.[30–35] As yet, reports on solvent H2O-EtOH solution and dried at 1058C.
extraction with the complexes of oxime compounds are
amphi-C10H12N4O3 [L1H2]; Yield; 1.17 g (%49). The
scarce.[36–43] Therefore, we have investigated the solvent product is soluble in H2O and DMSO, and slightly soluble in
extraction of metal cations through oxime compounds. In this DMF. It is insoluble in Et2O, CHCl3 and CCl4. Characterictic
work, we have investigated the effectiveness of four 13C NMR bands (DMSO-d6, d ppm): 145.16 (C1), 141.54
glyoxime derivatives in transferring the alkaline metal (C2), 133.11 (C3), 120.82 (C4), 123.06 (C5), 130.73 (C6),
cations (Liþ, Naþ, Kþ, Csþ) and transition metals (Co2þ
,
160.44 (C7), 26.89 (C8).
anti-C10H12N4O3 [L2H2]; Yield; 0.97 g (%43). The product
is soluble in H2O and DMSO, and slightly soluble in CHCl3. It
Ni2þ, Cu2þ, Zn2þ, Cd2þ, Hg2þ) and Pb2þ cation from the
aqueous phase into the organic phase.
In this paper, we report the synthesis and complex formation is insoluble in Et2O and CCl4. Characterictic 13C NMR bands
of four new substituted aminoglyoximes of unsymmetrically (DMSO-d6, d ppm): 144.86 (C1), 142.11 (C2), 134.58 (C3),
substituted vic-dioximes.
121.35 (C4), 124.46 (C5), 131.27 (C6), 161.01 (C7), 26.36 (C8).
amphi-C5H6N4SO2 [L3H2]; Yield; 0.84 g (%45). The
product is soluble in EtOH and DMSO, and slightly soluble
in CHCl3. It is insoluble in Et2O and CCl4. Characterictic
13C NMR bands (DMSO-d6, d ppm): 140.23 (C1), 150.94
(C2), 149.67 (C3), 132.78 (C4), 113.14 (C5).
EXPERIMENTAL
Materials and Measurement
All remaining reagents were purchased from Merck or
Fluka or Sigma Company and were used without further puri-
fication. Melting points were determined on a Gallenkamp
melting point apparatus and are uncorrected. Elemental
analyses (C, H, and N) were determined using a Leco,
CHNS-932 model analyzer. 1H, 13C NMR spectra were
recorded on a Bruker DPX-400 400 MHz High Performance
Digital FT-NMR and i.r spectra on a Perkin Elmer 1605
FT-IR spectrometer in KBr pellets. The pH was measured on
a Orion Expondoble Ion Analyzer EA 940. Mass spectra
were recorded on a MS 12 Mass spectrometer, Kratos at
70 eV and 2208C ion source temperature, electron impact ion-
ization. The u.v.-vis. spectra were recorded on a Shimadzu
160A spectrometer. Magnetic susceptibilities were determined
on a Sherwood Scientific Magnetic Susceptibility balance
(Model MK1) at room temperature using Hg[Co(SCN)4] as a
calibrate; diamagnetic corrections were calculated from
Pascal’s contants. The metal analyses were determined using
a Unicam 929 AAS spectrometer.
anti-C5H6N4SO2 [L4H2]; Yield; 0.76 g (%41). The product
is soluble in EtOH and DMSO, and slightly soluble in CHCl3.
It is insoluble in Et2O and CCl4. Characterictic 13C NMR bands
(DMSO-d6, d ppm): 139.58 (C1), 148.85 (C2), 148.06 (C3),
131.98 (C4), 113.42 (C5).
Table 1 gives the 1H NMR data for the above four ligands.
The colors, yields, melting points and elemental analyses, IR
and mass spectra data of the ligands are given Tables 2, 3
and 4, respectively.
Ni(II), Co(II), and Cu(II) Complexes of Amphi-
C10H12N4O3 [L1H2]
.
A solution of 5 mmol metal salt [NiCl2 6H2O (1.189 g),
.
.
CoCl2 6H2O (1.190 g), CuCl2 2H2O (0.852 g)] dissolved in
H2O (30 cm3), was added to a stirred solution of the ligand
(1.18 g, 5 mmol) dissolved in EtOH (30 cm3). On addition of
the metal salt, the pH dropped to 3.5–4.0 from 5.0 at the
onset of the reaction. After addition of a 1% NaOH solution
in H2O to raise the pH the mixture was stirred on a water
bath at 55–608C for 30 min. The precipitated complexes
were filtered off, washed with H2O and dried at 608C.
Synthesis
amphi- and anti-chloroglyoxime were prepared according to
published methods.[44,45] Experimental procedures are given
below.
Ni(II), Co(II), and Cu(II) Complexes of Anti-C10H12N4O3
[L2H2], Amphi-C5H6N4SO2 [L3H2] and, Anti-C5H6N4SO2
[L4H2]
Synthesis of Substituted Aminoglyoximes [L1–4H2]
.
To amphi-chloroglyoxime or anti-chloroglyoxime (1.225 g,
A solution of the metal salt (5 mmol) [NiCl6 6H2O
10 mmol) dissolved in Et2O (30 cm3), a solution of 4-aminoa- (1.189 g), CoCl2 6H2O (1.190 g), CuCl2 2H2O (0.852 g)]
cetanilide (1.50 g, 10 mmol) and 2-aminothiazol (1.00 g, in H2O (30 cm3) was added dropwise to a solution of the
10 mmol) in absolute EtOH (30 cm3) was added dropwise at ligand [L2H2 (2.36 g, 10 mmol) and L3H2, L4H2 (1.86 g,
room temperature with constant strirring. The reaction 10 mmol)] dissolved in 1:1 EtOH-H2O (30 cm3) mixture.
mixture was stirred continuously for 1 h. at room temperature. Upon adding metal salt, the pH of the mixtures dropped to
The pH of the solution, which decreased to ca. 4.0, was 3.5–4.0. After addition of a 1% NaOH solution in H2O to
adjusted to 5.5–6.0 with 1% KOH solution in EtOH. Ligands raise the pH to 5.0–5.5 the mixture was stirred on a water
were precipitated by addition of CH2Cl2 with continuous bath at 50–558C for 30 min. The precipitated complexes
stirring. The precipitated ligand was filtered off, washed with were filtered off, washed with H2O and dried at 1008C.
.
.

FOUR UNSYMMETRICALL VIC-DIOXIMES
613
TABLE 1
1H NMR spectra of the ligands in DMSO-d6 d (p.p.m.)
Compound
O-Ha
O-Ha
HArom
aHN-C55
55CH
-CH3
other
L1H2 amphi-
C10H12N4O3
11.16
s
(1H)
10.17
s
(1H)
6.41–7.21
dd
(4H)
7.69
s
8.19
s
2.01
s
O55CNH-Ar
9,51
(1H)
J(6.35)
7.77
s
(1H)
(3H)
S
(1H)
L2H2 anti-
C10H12N4O3
11.37
s
(1H
10.72
s
(1H
6.50–7.45
dd
(4H)
8.25
s
2.00
s
O55CNH-Ar
9,81
(1H)
(1H)
(3H)
s
(1H)
J(6.84)
6.93–6.53
d
L3H2 amphi-
C5H6N4SO2
11.01
s
(1H)
10.10
s
(1H)
8.19
s
7.94
s
(1H)
(1H)
(1H)
J(3.70)
6.85–6.50
d
L4H2 anti-
C5H6N4SO2
11.30
s
(1H)
10.70
s
(1H)
8.27
s
7.80
s
(1H)
J(3.68)
(1H)
(1H)
aDisappears on D2O exchange, s: singlet, d: doublet, dd: doublet of doublet; all J values are averages.
The colors, yields, melting points, elemental analyses and where A0 and A are the absorbencies in the absence and
IR spectral data of the compounds are given in Tables 2 and 3. presence of ligands, respectively.
Log Log Plot Analyses
To characterize the extraction ability, the dependence of the
Solvent Extraction
Picrate extraction experiments were performed following
Pedersen’s procedure.[46] 10 cm3 of a 2.1025 M aqueous
picrate solution and 10 cm3 1.1023 M solution of ligand in
CH2Cl2 were vigorously agitated in a stoppered glass tube
with a mechanical shaker for 2 min, then magnetically stirred
in a thermostated water bath at 258C for 1 h, and finally left
standing for an additional 30 min. The concentration of the
picrate ion remaining in the aqueous phase was then deter-
mined spectrophotometrically, as previously described.[43,47]
Blank experiments showed that no picrate extraction
occurred in the absence of ligand. The alkali picrates were
prepared as described elsewhere[43,47,48] by stepwise addition
of a 2.1022 M aqueous picric acid solution to a 0.14 M
aqueous solution of alkali metal hydroxide until neutralization,
which was checked by pH control with a glass electrode. They
were then rapidly washed with ethanol and ether before being
dried in vacuo for 24 h. Transition metal picrates were prepared
by successive addition of a 1.1022 M metal nitrate solution to
2.1025 M aqueous picric acid solution and shaken at 258C for
disribution coefficient D of the cation between the two phases
upon the ligand concentration was examined. If the general
extraction equilibrium to be given by Eq. (2).
nþ
M
þ nPicꢀðaqÞ þ x½LꢁðorgÞ ꢀ! ½MðPicÞnðLÞxꢁðorgÞ
ð2Þ
ðaqÞ
the overall extraction equilibrium constant is
½MðPicÞnðLÞxꢁ
Kex
¼
ð3Þ
n
x
½Mnþꢁ½Picꢀꢁ ½Lꢁ
and the distribution ratio D is defined by
½MðPicÞnðLÞxꢁ
D ¼
ð4Þ
½ðMnþÞꢁ
By introducing D into Eq. (4) and taking logarithm of both
sides, Eq. (5) is obtained.
n
log D ¼ logðKex½Picꢁ Þ þ xlog½Lꢁ
ð5Þ
Under these assumptions, a plot of log D versus log [L]
should be linear and its slope should be equal to the number
of ligand molecules per metal cation in the extracted species.
1 h. This metal picrates (Liþ, Naþ, Kþ, Csþ, Co2þ, Ni2þ, Cu2þ
Zn2þ, Cd2þ, Hg2þ, Pb2þ) were measure by u.v.-vis. using does
maximum wavelength 352 nm). The extractability of the metal RESULTS AND DISCUSSION
,
cations is expressed by means of the following equation (1):
Four new aminoglyoxime derivatives were prepared by
reacting aromatic amines with amphi-chloroglyoxime[44,45] or
anti-chloroglyoxime,[44,45] respectively. The structure of these
Extractabilityð%Þ ¼ ½ðA0 ꢀ AÞ=A0ꢁ ꢂ 100 ð1Þ

614
E. KARAPINAR ET AL.
TABLE 2
Colors, m.p., yields and elemental analytical results of the ligands and their complexes
Calculated (found) %
Yield
(%)
meff
(B.M.) Mp8C (dec)
Compounds
L1H2
Formulas
Color
C
H
N
amphi-C10H12N4O3 Reddish-
49
—
.300
50,8 (58.9) 5,1 (5,0)
23,7(23,7)
brown
[(L1H)(H2O)ClNi] C10H13N4O4ClNi
[(L1H)(H2O)ClCo] C10H13N4O4ClCo
[(L1H)(H2O)ClCu] C10H13N4O4ClCu
Green
Brown
Dark
36
58
79
2.96
4.21
1.79
.300
(286)
(248)
34,6 (34,5) 3,8 (3,7) 16,1 (16,0)
34,6 (34.4) 3,8 (3.5) 16,1 (16.1)
34,1 (34,1) 3,7 (3,7) 15,9 (15,8)
brown
Light
brown
Dark
reddish
Light
brown
black
L2H2
anti-C10H12N4O3
C20H22N8O6Ni
C20H22N8O6Co
C20H22N8O6Cu
43
45
70
—
.300
.300
50,8 (50.9) 5,1 (5,0) 23,7 (23.6)
45,4 (45,3) 4,2 (4.2) 21,2 (21,3)
[(L2H)2Ni]
[(L2H)2Co]
Dia.
1.92
(206) 45,4 (45,4) 4,2 (4.1) 21,2 (21,1)
[(L2H)2Cu]
L3H2
49
45
1.67
—
(192) 45,0 (44.9) 4,2 (4.1) 20,5 (20.5)
amphi-C5H6N4SO2 Dark
yellow
132
32.3 (32.0) 3.3 (3.1) 30.1 (30.2)
28.0 (28.2) 2.4 (2.3) 26.1 (25.9)
28.0 (27.6) 2.4 (2.2) 26.1 (26.0)
[(L3H)2Ni]
[(L3H)2Co]
C10H10N8O4S2Ni
Greenish-
brown
Dark
62
74
2.93
4.24
(144)
(175)
(170)
C10H10N8O4S2Co
brown
Green
Light
[(L3H)2Cu]
L4H2
C10H10N8O4S2Cu
anti-C5H6N4SO2
63
41
1.72
—
27.7 (27.7) 2.3 (2.3) 25.8 (25.8)
(154) 32.3 (32.1) 3.3 (3.2) 30.1 (29.9)
yellow
Brick red
Light
[(L4H)2Ni]
[(L4H)2Co]
C10H10N8O4S2Ni
C10H10N8O4S2Co
78
71
Dia.
1.91
(230)
(245)
28.0(27.8) 2.4 (2.3) 26.1 (26.0)
28.0 (28.1) 2.4 (2.2) 26.1 (26.1)
brown
Black
[(L4H)2Cu]
C10H10N8O4S2Cu
80
1.69
(249)
27.7 (27.5) 2.3 (2.2) 25.8 (25.7)
ligands were identified by employing elemental analyses, 13C group, since the effect of various substituents is expected to be
1
and H NMR, IR and mass spectroscopy (text-Tables 1–4, greater on the amidoxime group. The D2O exchangeable -NH-
respectively). The metal complexes were identified by elemen- protons of the aminoglyoximes measured at 7.69, 7.77, 8.19,
tal analyses and IR spectroscopy (Tables 2 and 3, respectively). 8.27 p.p.m., N55CH protons at 7.80–8.25 p.p.m. as singlets.
The general formulas of the ligands are shown in Figure 1.
Addition of D2O causes the disappearance of the -NH-and
-OH peak. These values are in good agreement with the
similar vic-dioximes.[9–27]
1H NMR Spectra of the Ligands
In the 13C NMR spectrum of LH2 carbon resonances of
the dioxime groups were observed around 139.58–
150.94 ppm. Observation of vic-dioxime and -OH protons in
In the 1H NMR spectra of the ligands, two peaks are present
for the -OH protons of the oxime groups. These two deuterium-
exchangeable singlets correspond to two non-equivalent -OH
protons which also indicate the configuration of the -OH
groups relative to each other[9,11,21] (Figure 1). When the
chemical shifts of the two -OH groups in the four different
ligands are compared, the ones at lower field quite closely
resemble each other (11.16, 11.37, 11.01, 11.30 p.p.m.)
whereas a considerable difference is observed for the shift at
the higher field (10.17, 10.72, 10.10, 10.70 p.p.m.). Conse-
quently, the first one is assigned to the -OH proton on the
1
the H NMR and of dioxime carbons in the 13C NMR spectra
at two different frequencies in each case, indicates that the
vic-dioxime has a structure.[50–53] All the signals in the
149.67–113.14 ppm range are assigned to the carbon atoms
of the aromatic rings.
IR Spectra of Ligands and Complexes
The ligands, -NH (3392–3442 cm21), -OH (3200–
aromatic side and the latter to the -OH proton of the amidoxime 3240 cm21), C55N-(1645–1605 cm21
)
and NO (955–

FOUR UNSYMMETRICALL VIC-DIOXIMES
615
TABLE 3
Characteristic IR bands of the ligands and their complexesa (KBr pellets)
n(C-H)
(aliph)
n(C-H)
(arom)
Compounds
n(N-H)
n(O-H)
n(O. . ..H. . . .O)
n(C55N)
n(N-O)
amphi-L1H2
[(L1H)(H2O)ClNi]
[(L1H)(H2O)ClCo]
[(L1H)(H2O)ClCu]
anti-L2H2
3396 w
3362 w
3373 w
3343 w
3400 w
3398 w
3396 w
3395 w
3440 m
3407 w
3405 w
3446 w
3442 m
3420 w
3446 w
3419 w
3240 m
3202 m
3221 w
3220 w
3200 w
—
2920 s
2926 s
2923 s
2927 s
2921 s
2924 s
2926 s
2923 s
2922 s
2929 s
2926 s
2926 s
2921 s
2923 s
2921 s
2925 s
3030 s
3035 s
3032 s
3024 s
3028 s
3036 s
3035 s
3022 s
3028 s
3023 s
3030 s
3031 s
3035 s
3035 s
3024 s
3026 s
—
—
1640 m
1607 w
1601 w
1605 w
1645 m
1611 w
1602 w
1612 w
1605 m
1618 m
1614 w
1598 w
1605 m
1600 w
1595 w
1595 m
970 w
972 w
976 w
973 w
965 w
962 w
960 w
960 w
955 w
968 w
966 w
961 w
960 w
955 w
953 w
958 m
—
—
—
[(L2H)2Ni]
1810 w
1810 w
1800 w
—
[(L2H)2Co]
—
—
[(L2H)2Cu]
amphi-L3H2
[(L3H)2Ni]
3210 w
3210 w
3240 w
3200 w
3208 w
—
1780 w
1785 w
1800 w
—
[(L3H)2Co]
[(L3H)2Cu]
anti-L4H2
[(L4H)2Ni]
1750 w
1800 w
1790 w
[(L4H)2Co]
—
—
[(L4H)2Cu]
acm21
.
TABLE 4
Mass spectral data of the ligands, (70 eV): m/e (rel. intensity)
L1H2
235,2 (28,8) (Mþ21); 219,2 (42,3); 217,2 (100); 173,2 (6.3); 162,2 (6,3); 161,2 (55,0); 159,1 (8.8); 139,1 (14,4);
93,1 (11,3); 79,1 (34,4).
L2H2
L3H2
L4H2
235,2 (23,7) (Mþ21); 219,2 43,8; 217,2 (100); 173,2 (8,2); 162,2 (5,6); 159,1 (8.8); 93,1 (5,9); 78,9 (70,6).
186.2 (36.4) (Mþ); 169.3 (25.2); 155.2 (100); 124.2 (40.1); 111.3 (28.1); 84.2 (72.9); 72.2 (16.0).
186.2 (19.6) (Mþ); 169.2 (27.8); 155.2 (100); 124.3 (54.2); 111.2 (30.5); 84.2 (70.0); 72.2 (15.7).
970 cm21) exhibit stretching frequencies as for substituted
aminoglyoximes[9–22, 49] (Table 3).
The complexes of L2H2 and L4H2 support the structures
shown in Figure 2 by the weak bending vibration of the
O-H. . .O bridges et.ca. 1750–1810 cm21 and shift of the
C55N vibration to lower frequencies (1595–1618 cm21) due
to N,N-metal coordination.[9,11,21,54] Meanwhile, the band
observed at 955–976 cm21 in the free anti-ligands, assigned
to the y(N-O) is shifted to lower frequency after complexation
(Table 3).
The metal complexes of L2H2, L3H2, and L4H2 were
prepared under similar conditions from the ligands and the cor-
responding metal salts by addition of a strong base. In all of
these complexes, the metal/ligand ratio was found to be 1:2
as found for most of the vic-dioximes.[9,11,21,54,55]
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 of one of the oxime group
and the O atom of the other, respectively. For L1H2, a
FIG. 1. General formulas of ligands.

616
E. KARAPINAR ET AL.
FIG. 2. Square-planar metal complexes of anti-L2H2 and anti-L4H2, R1: Me-
CONH-C6H4-, R2: C3H2NS-.
FIG. 4. Tetrahedral N,O-coordinated complexes of amphi-L3H2.
Cu(II) and Co(II) complexes of L2H2 and L4H2 ligands have
a square-planer geometry[21,52,53] and the metal complexes of
L1H2 and L3H2 ligands have a tetrahedral geometry.[9,11]
chloride ion and a water molecule are also coordinated to the
metal ion in [(L1H)Cl(H2O)M] (Figure 3). The elemental
analyses results and IR spectra are consistent with such a
structure.[9,11]
The distinctive colors of the amphi-and anti-LH2 complexes
with nickel (II) (greenish-brown and brick red, respectively)
Solvent Extraction
Up to now, studies related with solvent extraction with com-
plexes of oxime compounds are very limited. Therefore, this
work focused on elaboration of strategic requirements for the
two-phase extraction measurements. For this purpose, solvent
extraction experiments were performed to estimate the effective-
ness of ligands in transfering alkali metals (Liþ, Naþ, Kþ, Csþ)
and transition metals (Co2þ, Ni2þ, Cu2þ, Zn2þ, Cd2þ, Hg2þ) and
Pb2þ from the aqueous into organic phase. The results are sum-
marized in Table 5. These data were obtained using dichloro-
methane solutions of ligands to extract metal picrates from
aqueous solution according to Pedersen’s procedure.[46] The
equilibrium concentration of picrate in aqueous phase was
then determined spectrophotometrically.[43]
make the identification of these complexes straightforward[1]
.
As with most vic-dioximes,[9,11,21,54,55] the nickel(II)
complex of anti-L2H2 is planar N,N0-coordination is verified
by the diamagnetism of this compound, since it is known that
a d8 metal complex does not have unpaired electrons in a
square planar field.
In the IR spectrum of the paramagnetic amphi-L3H2
metal complexes, the -OH strecthing band appears at ca.
3202–3240 cm21 indicating that free -OH groups are present
in the molecule. Consequently, a N,O-chelated tetrahedral
structure can be proposed for these complexes (Figure 4).[11]
Mass Spectra of Ligands
As it can be interpreted from Table 5, the alkali metal
cations were not significantly extracted by ligands. However,
all the compounds extracted transition metals, in particular
Cu2þ and Hg2þ. The effectiveness in transferring transition
metals rather than the other metal cations by the synthesized
compounds indicates that a cation-p electron interaction is
operative since the metal is bounded by the opposite N, N or
N, O sites of these compounds. In this study, the extraction
data of ligands show a pronounced increased for the extraction
ability of Cu2þ and Hg2þ. The reason of high affinity of tran-
sition metals due to the soft donar nitrogen groups exist in
ligands causes the icrease in the extraction ability of these
ligands.[36–43]
The mass spectra of the ligands also support their structures
(Table 4). The molecular ion peak is 235.2 indicates the
formula weight of a L1H2 and L2H2 ligands. Also, the molecu-
lar ion peak of L3H2 and L4H2 is 186.2. Four ligands
give similar mass spectra. For example, the first fragment ion
is -OH.[9,11]
Magnetic Susceptibility of Complexes
Magnetic susceptibility measurement provide sufficient data
to characterize the structure of the complexes (Table 1). The
mononuclear complexes of Ni(II) are diamagnetic as
expected for d8 metal ion in a square-planer field,[2] and para-
magnetic as expected for d8 metal ion in a tetrahedral field
whereas the Co(II) and Cu(II) complexes are paramag-
netic.[52,53] For these complexes additional pysical and analyti-
cal data are given Table 3. According to these results, the
Despite the great affinity of nickel to aminoglyoximes, sur-
prisingly, after a contact time of 1 h. The extraction percentage
of nickel is very low, but that of copper is very high. Dioxime
compounds usually form stable N, N- or N,O- chelated com-
plexes containing a conjugated -N55C-C55N- or -N55C-
C55O- system, respectively.[43]
The high extraction percentage of Hg2þ is another surpris-
ing phenomenon in this work. The ionic radius of Hg2þ
,
which is 1.1 A8, cannot explain alone this phenomenon
because Pb2þ, which has a similar ionic radius to Hg2þ
,
could not be extracted as much as Hg2þ by all ligands.
The type of the donar atoms, polarizability effect, steric
hindrance and cavity size are probably important factors
here.[43]
FIG. 3. Metal complexes of amphi-L1H2.

FOUR UNSYMMETRICALL VIC-DIOXIMES
617
Figure 5a and b show the extraction of Cu2þ and Hg2þ into
dichloromethane at different concentrations of ligands, recpec-
tively. The observed metal-ligand ratios of Hg2þ and Cu2þ
with ligands are 1:2. For the systems the following logarithmic
extraction constants corresponding to Eq. (5) were determined
(Figure 5).
log Kex ¼ 12.74 (for Hg2þ with L1H2) log Kex ¼ 9.08
(for Cu2þ with L1H2)
log Kex ¼ 12.77 (for Hg2þ with L1H2) log Kex ¼ 12.33
(for Cu2þ with L1H2)
log Kex ¼ 12.36 (for Hg2þ with L1H2) log Kex ¼ 10.88
(for Cu2þ with L1H2)
log Kex ¼ 12.42 (for Hg2þ with L1H2) log Kex ¼ 10.49
(for Cu2þ with L1H2)
FIG. 5. log D versus log [L] for extraction of Cu picrate (5a) with ligands and
Hg picrate (5b) with ligands from an aqueous phase into dichloromethane at
258C.

618
E. KARAPINAR ET AL.
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