Synthesis of iminooxime derivatives and investigation of their complexes

Article abstract of DOI:10.1134/S1070328407090102

Three novel ligands, a-pycolyliminoisonitrosoacetophenone (L¹H ? HCl), α-pycolylimino-p-methylisonitrosoacetophenone (L²H ? HCl), and a-pycolylimino-p-chloroisonitrosoacetophenone L³H, were synthesized. Their metal complexes with Co(II), Cu(II), and Ni(II) were prepared. The mononuclear complexes of these ligands with Co²⁺, Cu²⁺, and Ni²⁺ ions were obtained in ethanol. The structures of the ligands and their complexes were characterized by 1H NMR, IR spectroscopy, elemental analyses, and magnetic susceptibility.

Full text of DOI:10.1134/S1070328407090102

ISSN 1070-3284, Russian Journal of Coordination Chemistry, 2007, Vol. 33, No. 9, pp. 680–684. © Pleiades Publishing, Ltd., 2007.
Synthesis of Iminooxime Derivatives and Investigation
of Their Complexes1
·
M. ¸Sahina, N. Koc¸akb, H. I. Uc¸ana, and M. A. Deveci†,a
a Department of Chemistry, Faculty of Arts and Sciences, Selc¸uk University, Konya, Turkey
b Faculty of Education, Department of Science Education, Selc¸uk University, Konya, Turkey
E-mail: musahin40@hotmail.com
Received July 13, 2007
Abstract—Three novel ligands, a-pycolyliminoisonitrosoacetophenone (L1H · HCl), α-pycolylimino-p-meth-
ylisonitrosoacetophenone (L2H · HCl), and a-pycolylimino-p-chloroisonitrosoacetophenone L3H, were synthe-
sized. Their metal complexes with Co(II), Cu(II), and Ni(II) were prepared. The mononuclear complexes of
these ligands with Co2+, Cu2+, and Ni2+ ions were obtained in ethanol. The structures of the ligands and their
complexes were characterized by 1H NMR, IR spectroscopy, elemental analyses, and magnetic susceptibility.
DOI: 10.1134/S1070328407090102
†
The early studies reported on derivatives of TUBITAK Laboratory (Center of Science and Technol-
monoglyoximes, diaminoglyoximes, heterocyclic vic- ogy Research of Turkey). IR spectra were recorded on
dioximes, tetraoximes, and their some transition metal a Perkin Elmer 1600 series spectrometer as KBr pellets,
complexes [1–4]. In addition to cobaltoximes, which Magnetic susceptibilities were determined on a Sher-
are regarded as vitamin B12 model compounds [5, 6], wood scientific magnetic susceptibility balance (Model
MK1) at room temperature (20°C) using
Hg[Co(SCN)2] as a calibrant; diamagnetic corrections
were calculated from Pascal’s constants.
the Schiff base complexes of cobalt and a number of
tetranitrogen macrocycles also serve as good models
[7–9]. The Co(III) complexes (cobaltoximes) readily
undergo reduction with NaBH4 to give blue Co(I) com-
pounds, which are capable of binding various alkyl or
aryl groups [10, 11]. The coordination chemistry of vic-
dioximes is interesting, and numerous transition metal
complexes of these ligands have been investigated [8].
The exceptional stability and unique electronic proper-
ties of these complexes can be attributed to their planar
structure stabilized by hydrogen bonding.
Isonitrosoacetophenone,
tophenone, and p-chloroisonitrosoacetophenone were
prepared according to published procedures [12, 13].
p-methylisonitrosoace-
Synthesis of a-picolyliminoisonitrosoacetophenone
(L1H · HCl). Isonitrosoacetophenone (5.0 mmol,
0.745 g) was dissolved in 40 ml of diethyl ether, and
then α-picolylamine (5.0 mmol, 0.54 g) was added
dropwise with stirring at room temperature. The color
of the solution was light yellow at first and turned dark
within 30 min by stirring. Then it was stirred 1 h more,
and absolute HCl gas was passed through this solution
in cold. The light yellow crystals formed were filtered
off, washed with diethyl ether, and dried in vacuum.
The final product was soluble in ethyl alcohol, DMSO,
and DMF. The yield was 0.97 g (70%).
Recently, several complexes of vic-dioximes and
their derivatives are known to exhibit an anti-tumor
activity for cancer researches. Another property of the
vic-dioximes is the liquid crystalline character. There-
fore, the aim of this study is to synthesize three new
ligands, L1H · HCl, L2H · HCl, and L3H, by the reac-
tions of 2-(aminomethyl)pyridine with isonitrosoace-
tophenone, p-methylisonitrosoacetophenone, and
p-chloroisonitrosoacetophenone and to prepare their
complexes with Ni2+, Co2+, and Cu2+ ions.
IR (ν, cm–1): 3478 ν(OHN), 3044 ν(CHar),
2878 ν(CHalif), 1633 ν(CN), 1467 ν(CC), 989 ν(NO).
1H NMR (δ, ppm): 12.60 s. (OH), 8.90 s. (HCN),
7.50–7.60 m. (CHar), 8.00–8.50 m. (CHPy), 4.30 s.
(=NCH2).
EXPERIMENTAL
Synthesis a-picolylimino-p-methylisonitrosoace-
tophenone (L2H · HCl). p-Methylisonitrosoacetophe-
none (5.0 mmol, 0.815 g) was dissolved in 40 ml of
diethyl ether, and then α-picolylamine (5.0 mmol,
0.54 g) was added dropwise with stirring at room tem-
perature. The color of the solution was light yellow at
first and turned dark within 30 min. Then it was stirred
1
Elemental analyses were determined and H NMR
spectra were recorded on a Bruker GmbH Dpx–400 MHz
high-performance digital FT-NMR spectrometer at the
†
Deceased.
1
The text was submitted by the authrs in English.
680

SYNTHESIS OF IMINOOXIME DERIVATIVES
681
Table 1. Elemental analyses data and some physical properties of iminooximes derivatives and their complexes
M.p.
Contents (calcd/found), %
Com-
pound
Empirical
formula
µeff, (de- Yield,
Color
µB comp.),
°C
%
C
H
N
M
Cl
L1H · HCl C14H14N3OCl
L2H · HCl C15H16N3OCl
Light
(210) 70 60.98/60.66 5.12/4.78 15.24/15.45
(215) 76.8 62.18/61.86 5.53/5.82 14.58/14.88
(220) 71.4 61.42/61.40 4.39/4.15 15.36/15.20
12.86/12.56
12.26/12.10
12.98/12.76
yellow
Light
yellow
L3H
C14H12N3OCl
Yellow
L1Cu
C14H12N3OClCu Brown 1.74 135
45 49.85/49.50 3.56/3.48 12.46/12.24 8.84/18.46 10.53/10.23
(L1H)2Ni C29H27N6O2Ni
Light 3.28 140
brown
40 55.29/55.68 5.28/5.87 13.82/13.42 9.66/9.25 11.68/11.37
(L1H)2Co C29H27N6O2Co Deep 3.15 160
brown
45 55.26/55.43 4.27/4.67 13.82/13.72 9.70/9.38 11.68/11.45
L2Cu
L2Ni
C15H14N3OClCu Green 1.71 102
52 51.28/41.36 3.99/3.76 11.96/12.41 18.09/18.00 10.11/9.95
36 52.00/53.74 4.04/4.28 12.13/13.72 16.95/16.55 10.25/10.53
C15H14N3OClNi Light
brown
104
(L2H)2Co C31H30N6O2Co Brown 3.80 170
48 56.60/57.05 4.72/4.42 13.21/13.48 9.28/9.68 11.16/11.50
60 45.22/45.42 3.96/4.08 11.30/11.54 17.09/17.28 19.11/19.46
50 45.81/45.44 3.00/3.48 11.45/11.48 16.00/16.22 19.36/19.05
65 45.77/45.27 3.00/2.68 11.44/11.22 16.08/16.53 19.35/20.05
L3Cu
L3Ni
L3Co
C14H11N3OCl2Cu Green 1.78 164
C14H11N3OCl2Ni Green 2.73 215
C14H11N3OCl2Co Light 1.98 210
brown
Table 2. Data of the 1H NMR spectra of the ligands in DMSO-d6 (δ, ppm)
Ligand
L1H · HCl
O–H
H–C=N
C–Har (C–HPy)
=N–CH2
CH3
12.60 s.
12.90 s.
12.65 s.
8.90 s.
8.85 s.
8.85 s.
7.50–7.60 m. (8.00–8.50) m.
7.50–7.70 m. (8.00–8.60) m.
7.60–7.85 m. (8.10–8.70) m.
4.30 s.
4.25 s.
4.30 s.
L3H
L2H · HCl
2.50 s.
1 h more, and absolute HCl gas was passed into this After 15 min yellowish crystals started to form. Stirring
solution in a cold medium. The light yellow crystals was continued further for 1 h. The crystals formed were
formed were filtered off, washed with diethyl ether, and filtered off, washed with ethanol, and dried in vacuum.
dried in vacuum. The final product was soluble in The final product was soluble in DMSO, DMF, and
DMSO, DMF, ethyl alcohol, and water. The yield was CHCl3. The yield was 0.98 g (71.4%).
IR (ν, cm–1): 3430 ν(OHN), 3030 ν(CHar),
1.12 g (76.8%).
IR (ν, cm–1): 3456 ν(OHN), 3047 ν(CHar), 2882 ν(CHalif), 1635 ν(CN), 1481 ν(CC), 995 ν(NO).
1H NMR (δ, ppm): 12.90 s. (OH), 8.85 s. (HCN),
2826 ν(CHalif), 1638 ν(CN), 1475 ν(CC), 992 ν(NO).
1H NMR (δ, ppm): 12.65 s. (OH), 8.85 s. (HCN), 7.50−7.70 m. (CHar), 8.00–8.60 m. (CHPy), 4.25 s.
7.60−7.85 m. (CHar), 8.10–8.70 m. (CHPy), 4.30 s. (=NCH2).
(=NCH2), 2.50 s. (CH3).
Synthesis of Ni(II), Co(II), and Cu(II) complexes
Synthesis a-picolylimino-p-chloroisonitrosoace- of L1H, L2H, and L3H. A solution of NiCl2 · 6H2O,
tophenone (L3H). p-Chloroisonitrosoacetophenone CoCl2 · 6H2O, or CuCl2 · 2H2O (5 mmol) dissolved in
(5 mmol, 0.920 g) was dissolved in 40 ml of absolute 20 ml of distilled water and added dropwise with stir-
ethanol and then 5 mmol (0.54 g) α-picolylamine was ring to a solution of ligand (5.0 mmol; 1.20 g of L1H,
added dropwise with stirring at room temperature. 1.27 g of L2H, or 1.37 g of L3H), which was dissolved
RUSSIAN JOURNAL OF COORDINATION CHEMISTRY Vol. 33 No. 9 2007

682
S¸ AHIN et al.
Table 3. IR spectrum (ν, cm–1) data of iminooximes derivatives and their complexes*
Compound
L1H
O–H···N
C–Har
C–Haliph
C=N
C=C
N–O
3478
3430
3456
3044
3030
3047
3036
3072
3045
3060
3061
3035
3071
3071
3067
2878
2882
2826
2860
2848
2890
2860
2848
2855
2853
2853
2853
1633
1635
1638
1606
1606
1608
1642
1648
1635
1645
1592
1589
1467
1481
1475
1425
1445
1463
1454
1453
1475
1445
1441
1476
989
995
992
967
900
974
989
990
976
896
906
890
L3H
L2H
L2Ni
(L2H)2Co
L2Cu
3415
(L1H)2Ni
(L1H)2Co
L1Cu
3412
3414
L3Ni
L3Co
L3Cu
* KBr pellets.
in 50 ml of ethyl alcohol. The pH of the reaction mix-
ture was adjusted from 3.0–3.5 to 5.0–5.5 with a 1%
NaOH solution. The formed complexes were stirred in
a water bath at 70°C for 30 min, then filtered off,
washed with water and alcohol, and dried in vacuum.
The obtained complexes were soluble in DMSO and
DMF.
1H NMR spectra of the ligands and their com-
1
plexes. All the H NMR spectra of the iminooxime
derivatives were taken in DMSO-d6 (Table 2). The
N−OH protons gave a low-field shift as a singlet in a
region of 12.65–12.90 ppm due to the intramolecular
hydrogen bonding [14–16]. The disappearance of this
peak by the addition of D2O to the solution evidenced
that this chemical shift belongs to the N–OH proton.
The elemental analyses data and some physical
properties of the ligands and their complexes are given
in Table 1.
Their 1H NMR and IR spectral data are presented in
Tables 2 and 3, respectively.
The protons (C–H) adjacent to the oxime groups lie
at 8.85 ppm [16−18]. The chemical shift values of the
aromatic protons of the benzene and pyridine rings
were observed at 8.70–7.50 ppm [14, 16]. The protons
of the =N–CH2– and –CH3 groups were observed at
4.25 and 2.50 ppm as singlets, respectively. The –CH2
protons adjacent to nitrogen exhibit low-field shifts
compared with their normal chemical shift values
[19−22].
RESULTS AND DISCUSSION
In the present work, the ligands have been synthe-
sized by two ways. L3H was synthesized by the reaction
of α-picolylamine with p-chloroisonitrosoacetophe-
none in absolute alcohol at room temparature. The
other compounds, L1H · HCl and L2H · HCl, were syn-
thesized by the reaction of α-picolylamine with isoni-
trosoacetophenone or p-methylisonitrosoacetophenone
in dry ether at room temperature. Moreover, these com-
pounds were obtained in the form of their hydrochlo-
ride salts, because no precipitates were formed in their
solutions in cold. The complexes of each ligand with
Ni2+, Co2+, and Cu2+ ions were isolated. The structures
of the ligands and their complexes were characterized
by elemental analyses, 1H NMR, and IR spectroscopy.
IR spectra of the ligands and their complexes. IR
spectroscopy results for the ligands and their metal
complexes are presented in Table 3. The IR spectrum of
the –OH group of oxime shows stretching vibration at
3450 and 2300 cm–1 instead of a band at 3300 cm–1
because of an intramolecular hydrogen bonding
(N····H–O–) [16]. The stretching band of the imine
group (C=N) of these compounds was observed at
1638–1630 cm–1. A band belonging to the N–O group
was observed at 990 cm–1. These values are in agree-
ment with literature [16, 23−25].
RUSSIAN JOURNAL OF COORDINATION CHEMISTRY Vol. 33 No. 9 2007

SYNTHESIS OF IMINOOXIME DERIVATIVES
683
According to the results of IR spectroscopy, elemen-
According to elemental analyses data and magnttic
tal analyses data, and melting points (~220°C decom- and IR spectrum data suggested structure of tetrahedral
position), the structures of the ligands may be written in (A) and octahedral (B) complexes are shown below:
the following form:
R
R
N
N
K
N
N
N
H
O
M
Cl
O
H
N
H
R = H, K = HCl;
R = CH3, K = HCl;
R = Cl.
(A)
By examining the IR spectra of the complexes, we
observed that the OH bands of the hydroxylimine group
(3450 and 2350 cm–1) of the ligands show a hydrogen
band bridge, which was present no more in the IR spec-
tra of L1Cu, L2Cu, L3Ni, L3Cu, and L3Co complexes.
Because of the absence of the OH band at 3200 cm–1 in
the IR spectra of the complexes, the central atom of the
complexes is bonded directly with oxygen of the oxime
group.
R
N
M
N
O
N
H
N
N
N
H
O
R
Moreover, the analyses for chlorine by the Mohr
method were performed for the ligands and complexes.
There are two chlorine ions bonded to the (L1H)2Ni,
(L1H)2Co, (L2H)2Ni, and (L2H)2Co complexes, and
only one chlorine ion is bonded with the coordination
sphere of the L1Co, L2Cu, L3Ni, L3Co, and L3Cu com-
plexes. This has been supported by the elemental anal-
yses data given in Table 1.
(B)
For A: R = H, L1M, M = Cu(II);
R = CH3, L2M, M = Cu(II);
R = Cl, L3M, M = Ni(II), Cu(II), and Co(II).
For B: R = H, (L1H)2M, M = Co(II), Ni(II);
R = CH3, (L2H)2M, M = Co(II).
Magnetic data of the complexes. The magnetic
susceptibility of the complexes has been examined. The
complex L2Ni has got four coordination of d8 configu-
ration, and the diamagnetic nature of the compound
shows that it acquires a square-planar structure. The
paramagnetic measured data for the Ni(II) complexes
has been found as 2.73 and 3.28 µB. According to these
data, the value 3.28 µB shows that the complexes can be
of tetragonal structure and sp3d2 hybridization. How-
ever, the value 2.73 µB indicates that the complexes can
be of tetrahedral structure. In addition, this structure
has been supported by the microanalyses. The com-
plexes of Co(II) and Cu(II) have got paramagnetic
properties. From them, the magnetic susceptibility of
the complexes having d7 configuration was measured
and found as 1.98 for CoL1, 3.15 for L2Co, and 3.30 µB
for L3Co. These data and those obtained from the
microanalyses show that the complex L1Co can be
square-planar and the complexes L2Co and L3Co can
have tetragonal structures. The Cu(II) complexes hav-
ing d9 configuration were also examined and were
found to exist in four coordination modes and their
magnetic susceptibility is equal to 1.70 µB. These data
are in agreement with literature [16, 22−24].
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