New glyoxime derivatives and their transition metal complexes

Article abstract of DOI:10.1134/S1070328407060061

Two new vic-dioxime ligands and their complexes with Co⁺², Ni⁺², Cu⁺², Cd⁺², and Zn⁺² ions were synthesized. Primer amines (3,4-methylenedioxaaniline and 4-methylbenzylamine) reacted with antichlorogl

Full text of DOI:10.1134/S1070328407060061

ISSN 1070-3284, Russian Journal of Coordination Chemistry, 2007, Vol. 33, No. 6, pp. 417–421. © Pleiades Publishing, Ltd., 2007.
New Glyoxime Derivatives and Their Transition
Metal Complexes1
B. Yildirim, E. Özcan, and P. Deveci
Department of Chemistry, Faculty of Arts and Sciences, Selcuk University, 42031 Konya, Turkey
e-mail: bilgekim@yahoo.com
Received June 9, 2006
Abstract—Two new vic-dioxime ligands and their complexes with Co+2, Ni+2, Cu+2, Cd+2, and Zn+2 ions were
synthesized. Primer amines (3,4-methylenedioxaaniline and 4-methylbenzylamine) reacted with antichlorogly-
oxime to give 3,4-methylenedioxaphenylaminoglyoxime (H2L1) and N-(4-methylbenzyl)aminoglyoxime
(H2L2) ligands. Structures of the ligands and their complexes are proposed based on elemental analyses, IR,
UV-Vis, and 1H NMR spectra, magnetic susceptibility measurements, and thermogravimetric analyses (TGA).
DOI: 10.1134/S1070328407060061
1
INTRODUCTION
Elemental analyses (C, H, N) were performed on a
LECO-932 CHNSO apparatus. IR spectra were
recorded on a Perkin Elmer Model 1605 FT-IR spectro-
vic-Dioximes and their complexes constitute an
important class of compounds having versatile reactiv-
ities [1]. Oxime metal chelates are biologically active
[2] and are reported to posses semiconducting proper-
ties [3, 4]. The substitution of the vic-dioxime moiety
affects the structure and stability of the complex [5].
Compounds containing the 1,3-dioxalane group are
used as solvents, additive compounds, and corrosion
retardants, while polymers containing 1,3-dioxalane
groups exhibit semiconducting behavior [6, 7].
1
photometer with KBr pellets. H NMR spectra were
recorded on a Bruker GmbH Dpx-400MHz high-per-
formance digital FT-NMR spectrometers in DMSO-d6.
Magnetic moments of the complexes were measured
using a Sherwood scientific model MX1 Gouy mag-
netic susceptibility balance at room temperature. TGA
curves were recorded on a Shimadeu TG-50 thermobal-
ance.
Synthesis of 3,4-methylenedioxaphenylaminogly-
oxime ligand (H2L1). A solution of 3,4-methylenediox-
aaniline (1.37 g, 0.01 mol) in CCl4 (30 ml) was added
to a solution of triethylamine (0.01 mol) in CCl4
(30 ml). This mixture was cooled from –5 to –10°C,
and a solution of anti-chloroglyoxime (1.23 g,
0.01 mol) in diethylether (30 ml) was added with con-
tinuous stirring. Addition of an anti-chloroglyoxime
solution was carried out over 1 h. After the mixture was
stirred for 1 h more, the temperature raised to 5°C. The
precipitated triethylamine salt was filtered off, and the
filtrate was evaporated to remove the solvent. The oily
product was dissolved in CHCl3 and recrystallized from
a mixture of chloroform–n-hexane (1 : 5). The obtained
product was filtered off, washed with diethylether sev-
eral times, and dried in vacuum. The purified ligand is
soluble in common solvents, such as DMSO, DMF, and
dioxane, and insoluble in diethyl ether, ethanol, and
vic-Dioximes have a high tendency to form isomers.
When the molecule is formally symmetrical, three
forms are possible: syn-, anti-, and amphi-structures,
usually the stability order of these forms is anti- >
amphi- > syn-configuration, but there are some excep-
tions. The dioxime anti-isomers are responsible for the
formation of brightly colored chelate derivatives with
nickel and other transition metal ions [8–10]. Espe-
cially, the anti-form gives blood-red complexes with
nickel ions.
This paper describes the synthesis of novel soluble
vic-dioxime ligands and their complexes with
nickel(II), copper(II), cobalt(II), cadmium(II), and
zinc(II). As far as we know, this is the first report on
these ligands.
1
EXPERIMENTAL
n-hexane. Characteristic H NMR peaks (DMSO-d6,
400 mHz), δ, ppm: 6.12 (s., 2H, –O–CH2O–), 7.52 (s.,
1H, H–C = N), 6.14 (s., 1H, N–H), 10.71–11.88 (s., 2H,
N–OH), 7.11–7.80 (m., 3H, Ar–H).
Synthesis of complexes [Ni(H2L1)2] (I),
[Co(H2L1)2(H2O)2] (II), and [Cu(H2L1)2] (III). The
ligand (2.23 g, 1 mmol) was dissolved in absolute
The preparation of anti-chloroglyoxime has been
described previously [11]. All the reagents used were
purchased from Merck, Fluka, or Sigma and were
chemically pure.
1
The article was submitted by the authors in English.
417

418
YILDIRIM et al.
methanol (10 ml), and a solution of 0.5 mmol of the washed with EtOH and dried in vacuum at 60°C. Char-
1
appropriate metal salt (CoCI2 · 6H2O (0.12 g), NiCI2 · acteristic H NMR peaks for (H2L2)2Ni (DMSO-d6,
6H2O (0.12 g), or CuCl2 · 2H2O (0.09 g)) in absolute 400 mHz), δ, ppm: 2.23 (s., 6H, −CH3), 4.52 (s., 4H,
methanol (5 ml) was added dropwise to the ligand solu- −CH2), 7.03 (s., 2H, H–C=N), 5.62 (s., 2H, N−H), 14.80
tion with continuous stirring. The color of the solution (s., 2H, O···H–O), 6.90–7.21 (m., 6H, Ar–H).
Synthesis of complexes [Cd(H2L2)Cl] · H2O (VII),
immediately turned dark brown for Co(II), tile red for
Ni(II), and green for Cu(II). The pH of the solution,
and [Zn(H2L2)Cl] · H2O (VIII). The ligand H2L2
which decreased to 3.5, was adjusted to 5–6 by the
addition of a 1% triethylamine solution in ethanol.
Each mixture was stirred for more than 1 h at 30°C. The
precipitated complexes were kept on a water bath for
35 min at 40°C and filtered, and the precipitate was
washed with water, ethanol, and diethylether. The com-
plexes are soluble in DMSO, DMF, and THF and insol-
uble in diethylether, water, ethanol, and n-hexane.
Characteristic 1H NMR peaks for (H2L1)2Ni (DMSO-d6,
400 mHz), δ, ppm: 6.10 (s., 4H, –O–CH2–O), 7.21 (s.,
2H, H–C=N), 6.08 (s., 2H, N–H), 14.89 (s., 2H, O···H–O),
6.91–7.2 (m., 6H, Ar–H).
Synthesis of complex [Cd(H2L1)Cl] · H2O (IV). The
ligand (2.23 g, 1 mmol) was dissolved in absolute
methanol (10 ml). A solution of metal salt CdCl2 · H2O
(0.21 g, 1 mmol) in absolute methanol (10 ml) was
added dropwise to the ligand solution with continuous
stirring. The apparent pH of the solutions was adjusted
to 5–5.5 by the addition of a 1% triethylamine solution
in ethanol. The mixture was further stirred on a water
bath at 50°C for 2 h in order to complete precipitation.
The precipitate was filtered, washed with diethyl ether,
and dried in vacuum. The complex is soluble in THF,
DMF, and DMSO and insoluble in diethylether, etha-
nol, and n-hexane.
(2.07 g, 1 mmol) was dissolved in absolute ethanol
(15 ml). Solutions of metal salts CdCI2 · H2O (2.03 g,
1 mmol), ZnCI2 (1.38 g, 1 mmol) in absolute ethanol
(15 ml) were added dropwise to a ligand solution with
continuous stirring at 60°C. The color of the solutions
immediately changed. The reaction mixture was stirred
at this temperature for 3 h and filtered, and the precipi-
tate was washed with water, ethanol, and diethyl ether
and dried in vacuum at 60°C.
RESULTS AND DISCUSSION
3,4-Methylenedioxaphenylaminoglyoxime (H2L1)
and N-(4-methylbenzyl)aminoglyoxime (H2L2) were
obtained from the anti-chloroglyoxime and 3,4-methyl-
enedioxaaniline or 4-methylbenzylamine:
OH
OH
H
N
N
C
C
NH
O
O
(H2L1)
Synthesis of N-(4-methylbenzyl)aminoglyoxime
ligand (H2L2). 4-methylbenzylamine (2 × 10–2 mol) was
dissolved in ethanol (5 ml). A solution containing anti-
chloroglyoxime (1.23 g, 1 × 10–2 mol) in ethanol (5 ml)
was added slowly at room temperature with constant
stirring. The mixture was stirred for 2 h. The pH of the
mixture was about 7.0–7.5. Its volume was then dou-
bled by adding distilled water. The resulting white pre-
cipitate was filtered off, washed with cold water, dried,
and crystallized from a water–ethanol (1 : 3) mixture.
The title compound is soluble in diethyl ether, DMF,
DMSO, dioxane, and ethanol and less soluble in water
and chloroform. Characteristic 1H NMR peaks (DMSO-d6,
400 mHz), δ, ppm: 2.10 (s., 3H, –CH3), 4.51 (s., 2H,
−CH2), 7.14 (s., 1H, H–C=N), 5.94 (s., 1H, N–H),
10.31—11.32 (s., 2H, N–H), 7.00–7.21 (m., 4H).
H3C
CH2NH
OH
OH
C
C
N
N
H
(H2L2)
The ligand and their complexes were characterized
by elemental analyses, IR, 1H NMR, UV-Vis spectros-
copy, thermogravimetric analyses (TGA), differential
thermal analysis (DTA), and magnetic susceptibility.
The elemental analyses of H2L1 and its Co(II),
Cd(II), Ni(II), and Cu(II) complexes are in agreement
with theoretical expectations (Table 1). The analytical
and physical data show a metal : ligand ratio of 1 : 2 for
Ni(II), Co(II), and Cu(II). The complexation of H2L1
with Cd(II) gives a product with a 1 : 1 metal : ligand
ratio. The reaction of the ligand and Ni(II), Co(II),
Cu(II), and Cd(II) salts yield complexes corresponding
to the general formulas [Ni(H2L1)2], [Co(H2L1)2(H2O)2],
[Cu(H2L1)2], and [Cd(H2L1)Cl] · H2O.
Synthesis of complexes [Ni(H2L2)2] (V),
[Co(H2L2)2(H2O)2] (VI). A solution of metal salt NiCI2 ·
6H2O (1.189 g, 0.5 mmol), CoCl2 · 6H2O (1.19 g,
0.5 mmol) dissolved in EtOH (5 ml) was added to a
stirred solution of H2L2 (2.07, 1 mmol) dissolved in
EtOH (5 ml). The mixture was heated to 60°C, and 1 M
The elemental analyses of H2L2 and its Co(II),
NaOH solution in ethanol was added dropwise. The Ni(II), Cd(II), and Zn(II) complexes are in agreement
reaction was allowed to continue for 3 h at 60°C. The with theoretical expectations (Table 1). The analytical
mixture was allowed to stand for 1day at room temper- and physical data show a metal : ligand ratio of 1 : 2 for
ature. The precipitated complexes were filtered off, Ni(II) and Co(II). The complexation reaction of H2L2
RUSSIAN JOURNAL OF COORDINATION CHEMISTRY Vol. 33 No. 6 2007

NEW GLYOXIME DERIVATIVES
419
Table 1. Elemental analysis data for the H2L1, H2L2 and compounds I–VIII and some of their physical properties
Content (found/calcd), %
Compound
Empirical formula
Color
M.p., °C Yield, %
C
H
N
H2L1
[C9H9N3O4]
White
Red
169
55
80
45
48
51
49
73
71
62
65
49.10/48.43 3.97/4.03 18.81/18.83
43.09/42.96 3.13/3.18 16.64/16.70
40.16/40.08 3.65/3.71 15.43/15.58
42.50/42.56 2.90/3.15 15.95/16.55
27.93/27.85 2.53/2.58 10.86/10.83
57.95/57.98 6.39/6.28 20.27/20.29
51.06/51.01 4.99/5.09 17.74/17.83
47.25/47.36 5.45/5.52 17.09/16.56
33.73/33.85 3.56/3.67 11.97/11.85
39.18/39.08 4.35/4.23 13.80/13.66
[Ni(H2L1)2] (I)
[C18H16N6O8Ni]
282
[Co(H2L1)2(H2O)2] (II)
[Cu(H2L1)2] (III)
[C18H20N6O10Co] Brown
[C18H16N6O8Cu] Brown
184*
160*
183*
154
[Cd(H2L1)Cl] · H2O (IV) [C9H10N3O5ClCd] Green
H2L2
[C10H13N3O2]
White
[Ni(H2L2)2] (V)
[Co(H2L2)2(H2O)2] (VI)
[C20H24N6O4Ni]
[C20H28N6O6Co]
Tile red
Brown
266
251*
247*
250*
[Cd(H2L2)Cl] · H2O (VII) [C10H13N3O2ClCd] Yellow
[Zn(H2L2)Cl] · H2O (VIII) [C10H13N3O2ClZn] Yellow
* Decomposition point.
with Cd(II) and Zn(II) gives a product with a 1 : 1
metal : ligand ratio. The reactions of the ligand and
Ni(II), Co(II), Cd(II), and Zn(II) salts yield complexes
corresponding to the general formula [Ni(H2L2)2],
[Co(H2L2)2(H2O)2], [Cd(H2L2)Cl] · H2O, [Zn(H2L2)Cl] ·
H2O.
O
H
O
N
O
N
H
L
O
N
L
L
L
L
N
M1
M2
N
O
N
O
N
O
N
O
H
H
H
H
L
H
H
(A)
(B)
In the IR spectrum of the ligands, the most charac-
teristic peaks appear around 960–970 ν(N–O), 1610–
1640 ν(C=N), 3370–3420 ν(N–H), and 3368–3398 cm–1
ν(O−H) and exhibit streching frequencies as substituted
aminoglyoxi-mes [5, 12, 13].
M1 = Ni2+, Cu2+; M2 = Co2+; L = C9H8N3O4 for H2L1;
C10H12N3O2 for H2L2.
The weak bands appearing around 1720–1730 cm–1
in the IR spectra of the complexes correspond to
intramolecular hidrogen bridges (O···H–O) but these
peaks are missing for the ligand [16].
In the IR spectra of the Co(II), Ni(II), and Cu(II)
complexes with H2L1 ligand, the absorption assigned to
the ν(C=N) frequency in the free ligand is shifted to
lower frequencies (1605–1610 cm–1) after complexation
due to N,N–metal coordination [14, 15]. At the same
time, the band observed at 960 cm–1 in the free ligand,
which is assigned to ν(N–O), is shifted to different fre-
quencies after complexation. Since in the IR spectra of
the Ni(II) and Cu(II) complexes, the OH absorption
bands did not appear, the geometry of these complexes
is suggested to be square-planar (A), while the Co(II)
complexes of the same ligand appear to have octahedral
structures (B) due to coordination with water mole-
cules, which appear as a band at ~3450 cm–1.
In the IR spectra of the Cd(II) the stretching band of
ν(C=N) appearing at 1626 cm–1 in H2L1 is shifted to
–1
…
1616 cm . There is no (O H–O) peak, as expected for
complexes with the formula A and B. At the same time,
the N–O band at 960 cm–1 in the free ligand was shifted
to lower frequency by 20 cm–1 after Cd(II) complex for-
mation. These results suggest that the ligand is coordi-
nated to metal ions through nitrogen and oxygen
donors. A chloride ion and a water molecule are also
coordinated to each metal ions. A broad band at
3452 cm–1 was observed in the spectra of these com-
plexes containing coordinated water molecules [17].
RUSSIAN JOURNAL OF COORDINATION CHEMISTRY Vol. 33 No. 6 2007

420
YILDIRIM et al.
Table 2. Characteristic IR bands (cm–1) of the ligands and complexes*
Compound
ν(O–H )
ν(N–H )
ν(O···H–O )
ν(C=N)
ν(N–O )
Others
H2L1
3394
3420
3395
3390
1626
1610
1610
960
941
923
1097 (C–O–C)
1038 (C–O–C)
I
1726
1730
II
3410
1040 (C–O–C)
3450 (H2O)
III
IV
3380
3392
1720
1605
1616
944
940
1032 (C–O–C)
3398
3368
1038 (C–O–C)
3452 (H2O)
H2L2
3415
3389
3373
3370
3380
1640
1626
1625
1625
1630
970
960
960
962
965
I
1710
1710
II
3395
3396
3398
3456 (H2O)
3440 (H2O)
3430 (H2O)
III
IV
* KBr pellets.
The IR spectra of the complexes with H2L2 ligand and oxygen donors. A chloride ion and a water mole-
cule are also coordinated to each metal ion. So the
[Cd(H2L1)Cl] · H2O, [Cd(H2L2)Cl] · H2O and
[Zn(H2L2)Cl] · H2O complexes have suggested tetrahe-
dral structure (C):
support the structures by the weak bonding vibration of
the ν(O···H–O) bridges around 1710 cm–1 and the shift
of the C=N vibration to lower frequencies of 1625–
1640 cm–1 due to N,N–metal coordination [18]. The
band observed around 970 cm–1 in the free ligand,
which is assigned to ν(N–O), is shifted to a lower fre-
quency after complexation (Table 2). The absorptions
indicate that the oxime group take part in complexation.
R
N
O
M
OH2
Cl
H
N
In the IR spectrum of the Zn(II) complex the stretch-
ing band of ν(C=N) appearing at 1640 cm–1 in H2L2 is
shifted to 1630 cm–1. There is no (O···H–O) peak, as
expected for complexes with the structure C. At the
same time, the N–O band at 970 cm–1 in the free ligand
was moved to lower frequencies by ca. 10 cm–1 after
Zn(II) complex formation. These results suggest that
the ligand is coordinated to metal ions through nitrogen
OH
(C)
M = Cd2+, Zn2+; L = C9H8N3O4 for H2L1;
C10H12N3O2 for H2L2.
1
In the H NMR spectrum of the ligands, since the
OH protons of oximes H2L1 and H2L2 are equivalent in
the (E,E)-form, two peaks were observed for the pro-
tons [19]. In these ligands, chemical shifts of =N–OH
protons were observed around 10.31–11.88 ppm as sin-
glets. The singlets, which belong to OH, disappear after
the addition of D2O. A single chemical shift for the OH
proton indicates that the oxime groups prevail in the
anti-form [20].
Table 3. Magnetic moments and electronic spectral data of
complexes I–VIII
Compound
µeff/atom, µB
λmax, nm*
I
Dia
3.95
1.59
Dia
Dia
2.14
Dia
Dia
475, 329, 274
485, 330, 280
490, 335, 285
The geometric isomers of the [(HL1)2Ni] and
[(HL2)2Ni] complexes can be inferred from the 1H NMR
spectrum, since the alternative chemical environments
will show two O···H–O bridge protons in the cis-form
but only one 1H NMR resonance in the trans-structure,
and this result can easily be supported by deuterium
II
III
IV
V
473, 301, 256
487, 310, 267
1
VI
VII
VIII
exchange. The observed spectrum has only one H
NMR resonance at 14.80–14.89 ppm, suggesting the
trans-form of the complex [21].
The electronic spectra of complexes I–VIII were
taken in DMSO (Table 3). The spectra of the complexes
* DMSO.
RUSSIAN JOURNAL OF COORDINATION CHEMISTRY Vol. 33 No. 6 2007

NEW GLYOXIME DERIVATIVES
Table 4. TGA data of the H2L1 and H2L1 ligands and their complexes
421
Compound
Stability
Step 1
Step 2
Weight loss, %
Residue
H2L1
I
25–152
25–270
25–169
25–151
25–173
25–135
25–258
25–245
25–240
25–238
152–440
270–400
169–340
151–299
173–468
135–420
258–400
245–410
240–398
238–402
493–610
420–582
405–620
302–746
543–589
462–634
420–593
435–643
421–560
432–580
90
86
87
85
67
94
84
86
65
75
NiO
CoO
CuO
CdO
II
III
IV
H2L2
V
NiO
CoO
CdO
ZnO
VI
VII
VIII
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attributed to the L
M (charge–transfer) transition,
which is compatible with this complexes having a
square-planar structure [21].
Magnetic susceptibility measurements provide suf-
ficient data to characterize the structure of the com-
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complexes are paramagnetic and their magnetic sus-
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over a temperature range of 25–800°C. The decomposi-
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were calculated from the TGA data (Table 4). As can be
seen from the TGA data (Table 3), all the complexes and
ligands decompose in two steps at different temperature
ranges. All these complexes undergo complete decom-
position to the corresponding metal oxides: NiO, CoO,
CuO, CdO, or ZnO.
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ACKNOWLEDGMENTS
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This work was supported by the Management Unit
of Scientific Research Projects of Selcuk University
(SU-BAP), project no. 05401054 under thesis. Projects
are gratefully acknowledged.
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