Synthesis and complex formation of substituted thio-p-nitrophenylglyoximes of unsymmetrical vic-dioximes

Article abstract of DOI:10.1081/SIM-100001936

The reaction of anti-chloro(p-nitrophenyl)glyoxime (CPN-PGH₂) with thiophenol, 4-methylthiophenol and 4-methoxythiophenol in ethanol between -5° and 10°C gives unsymmetrical vic-dioximes, designated as thiophenolo-p-nitrophenylglyoxime [L¹

Full text of DOI:10.1081/SIM-100001936

Synthesis and Reactivity in Inorganic and Metal-Organic
Chemistry
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SYNTHESIS AND COMPLEX FORMATION OF
SUBSTITUTED THIO-p-NITROPHENYLGLYOXIMES OF
UNSYMMETRICAL vic-DIOXIMES
H. Cahit Sevindir
To cite this article: H. Cahit Sevindir (2001) SYNTHESIS AND COMPLEX FORMATION OF
SUBSTITUTED THIO-p-NITROPHENYLGLYOXIMES OF UNSYMMETRICAL vic-DIOXIMES,
Synthesis and Reactivity in Inorganic and Metal-Organic Chemistry, 31:1, 107-113, DOI: 10.1081/
SIM-100001936
To link to this article: http://dx.doi.org/10.1081/SIM-100001936
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SYNTH. REACT. INORG. MET.-ORG. CHEM., 31(1), 107–113 (2001)
SYNTHESIS AND COMPLEX
FORMATION OF SUBSTITUTED
THIO-p-NITROPHENYLGLYOXIMES
OF UNSYMMETRICAL vic-DIOXIMES
H. Cahit Sevindir
Department of Environmental Engineering, Faculty of
Engineering, Su¨leyman Demirel University, Isparta, Turkey
ABSTRACT
The reaction of anti-chloro(p-nitrophenyl)glyoxime (CPN-
PGH2) with thiophenol, 4-methylthiophenol and 4-methoxy-
thiophenol in ethanol between −5◦ and 10◦C gives unsymmetrical
vic-dioximes, designated as thiophenolo-p-nitrophenylglyoxime
[L1H2], 4-methyl-thiophenolo-p-nitrophenylglyoxime[L2H2], and
4-methoxythiophenolo-p-nitro-phenylglyoxime[L3H2]. TheNi(II)
and Cu(II) complexes of these ligands were prepared and are pro-
posed to be square-planar, while the also prepared Co(II) complexes
are proposed to be octahedral with water molecules as axial ligands.
1
The structural assignments are supported by H NMR, IR, and
elemental analyses.
E-mail: sevindir@mmf.sdu.edu.tr
107
Copyright ꢀ 2001 by Marcel Dekker, Inc.
www.dekker.com
C

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108
SEVINDIR
O2N
O2N
OH
OH
OH
N
N
N
C
C
C
C
+
R
SH
S
N
Cl
R
OH
Figure 1. General formulas of ligands: L1H2: R=C6H5; L2H2: R= p-CH3C6H4; L3H2:
R= p-CH3OC6H4.
INTRODUCTION
The transition metal complexes of vic-dioximes have been of particular inter-
est as biological model compounds (1). The substitution pattern of the vic-dioxime
moiety affects the structure and stability of the complexes; e.g., Co(II) complexes
of dialkyl- or diarylglyoximes and dithioglyoximes can be obtained by the reduc-
tion of octahedral Co(III) compounds (2,3), but the complexes decompose in the
case of diaminoglyoxime derivates (4).
In this paper, we report the synthesis and complex formation of three new
substituted thio-R-p-nitrophenylglyoximes as examples of unsymmetrically sub-
stituted vic-dioximes. The low symmetry of the ligands is also expected to enhance
the solubility of planar complexes derived from them. A general formula of the
ligands is shown in Figure 1. The ligand structures were verified by elemental
analyses, 1H NMR and IR spectral data (Tables 1–3).
RESULTS AND DISCUSSION
The number of vic-thiodioximes and thioximes in the literature (5–7) are
rather few. The structures of L1H2, L2H2, and L3H2 were investigated by 1H NMR
and IR spectra. In the 1H NMR spectra of the ligands, two deuterium exchangeable
singlets are observed, corresponding to two nonequivalent OH protons in the anti-
configuration (8). When the chemical shift values of the two OH groups in the three
ligands are compared, the peaks at lower field vary little (11.60–11.40 ppm), while
a considerable difference is observed for those at higher field (10.50–10.10 ppm)
(Table 2). The former is assigned to the OH proton adjacent to the phenyl, and the
latter to the OH proton of the thioxime group (8,9). The methylene protons occur
at 2.20 ppm as singlets.
Except for (L1H)2 Ni, the solubility of the complexes prepared from the three
new unsymmetrical ligands is not sufficient to obtain 1H NMR solution spectra on
our 100 MHz instrument. The proton NMR spectrum of diamagnetic (L1H)2 Ni

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THIO-p-NITROPHENYLGLYOXIME COMPLEXES
109
Table 1. Melting Points, Yields, and Elemental Analyses of the Ligands and Their
Complexes
Mol. Yield M.p.,◦C
Compounds
wt.
%
(d.p.)
%C
%H
%N
%S
%M
C14H11SN3O4
L1H2
317
75
148
52.99
3.47
13.24
10.09
–
(52.97) (3.46) (13.24) (10.06)
48.64 2.89 12.16 9.26
C28H20S2N6O8Ni 690.7 81
(190)
(199)
(180)
(138)
(175)
(185)
(200)
150
8.49
(L1H)2Ni
(48.60) (2.88) (12.15) (9.24) (8.49)
48.31 2.89 12.07 9.20 9.13
(48.30) (2.88) (12.05) (9.18) (9.11)
46.22 3.30 11.55 8.80 8.10
(46.20) (3.29) (11.52) (8.78) (8.10)
54.38
(54.38) (3.90) (12.67) (9.65)
50.09 3.33 11.68 8.90
(50.10) (3.32) (11.67) (8.88) (8.15)
49.75 3.31 11.61 8.84 8.77
(49.74) (3.30) (11.59) (8.83) (8.75)
47.68 3.70 11.12 8.47 7.80
(47.68) (3.69) (11.10) (8.45) (7.79)
51.87
(51.85) (3.71) (12.09) (9.19)
47.95 3.19 11.18 8.52
C28H20S2N6O8Cu 695.5 90
(L1H)2Cu
C28H24S2N6O10Co 726.9 70
(L1H)2(OH2)2)Co
C15H13SN3O4
L2H2
307
75
3.92
12.68
9.66
–
C30H24S2N6O8Ni 718.7 80
8.16
(L2H)2Ni
C30H24S2N6O8Cu 723.5 80
(L2H)2Cu
C30H28S2N6O10Co 754.9 75
(L2H)2(OH2)2Co
C15H13SN3O5
L3H2
323
70
3.74
12.10
9.22
–
C30H24S2N6O10Ni 750.7 80
(200)
(180)
(196)
7.81
(L3H)2Ni
(47.94) (3.19) (11.17) (8.49) (7.80)
47.65 3.17 11.11 8.47 8.40
(47.63) (3.17) (11.09) (8.46) (8.40)
45.74 3.55 10.67 8.13 7.48
(45.73) (3.54) (10.65) (8.10) (7.47)
C30H24S2N6O10Cu 755.5 85
(L3H)2Cu
C30H28S2N6O12Co 786.9 80
(L3H)2(OH2)2Co
indicates O–H . . . O bridge formation by the strong shift of the OH protons to
lower field (14.80 ppm) compared to the free ligand (4,8,9).
1
The geometric isomerism of (L1H)2Ni can be inferred from the H NMR
–
spectrum, since the alternative chemical environments will show two O H . . . O
bridge protons in the cis-form, but only one in the trans-structure. The observed
spectrum has only one resonance at 14.8 ppm suggesting the trans-form of the
complex (Fig. 2).
−1
IntheIRspectraoftheligands,C S(685–670cm ),O H(3260–3280 cm−1),
–
–
C N (1620–1640 cm ), and N O (970–990 cm−1) stretches appear at frequen-
cies expected for substituted aminoglyoximes (9–11) (Table 3). The elemental
analyses results and characteristic IR absorptions of the complexes are given in
Tables 1 and 3. The metal-ligand ratio in all of the complexes is 1:2, but the Co(II)
complexes have coordinated two additional water molecules for each metal ion.
−1
–
=

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SEVINDIR
Table 2. 1H NMR Data (δ, ppm) for the Ligands (in DMSO-d6) and Ni(II)
Complexes (in CF3COOH)
a
a
–
–
–
Cpd.
L1H2
O H
O H
O H . . . O OCH3
H(arom).
CH3
11.60
(1H), s (1H), s
10.50
–
–
–
–
7.58–6.52
(9H), m
7.40–7.70
(18H), m
7.68–6.80
(8H), m
–
(L1H)2Ni
L2H2
–
–
14.80
(2H), s
–
–
11.50
10.40
2.20
(3H), s
–
(1H), s (1H), s
11.40 10.10
(1H), s (1H), s
L3H2
–
3.8
7.62–6.56
(8H), m
(3H), s
aDisappears on D2O exchange.
s: Singlet; m: Multiplet.
Thus, it is reasonable to propose an octahedral structure for Co(II) and squar planar
coordination for the Ni(II) and Cu(II) compounds (Fig. 2).
The IR spectra of the complexes support these structures −b1y the weak bend-
–
ing vibration of the O H . . . O bridges around 1670–1690 cm and the shift of
the C N vibration to lower frequencies at 1630–1660 cm−1 due to N,N-metal co-
=
Table 3. Characteristic IR Bands (cm−1) of the Ligands and Their Complexes
–
–
N O
–
C S
=
C N
Cpd. No
OH
CHarom
.
O H . . . O
L1H2
3260 s
–
–
3070 s
3040 s
3030 s
–
1625 s
1630 s
1640 s
970 s 685 w
960 s 670 w
960 s 680 w
(L1H)2Ni
(L1H)2Cu
1670 m
1690 m
(L1H)2(OH2)2Co 3560 s
3320 s
3020 s
3060 s
3050 s
3030 s
3050 s
1680 m
–
1690 m
1670 m
1690 m
1630 m 940 s 675 w
L2H2
3260 s
–
–
1620 s
1640 s
1640 s
980 s 670 w
970 s 670 w
970 s 685 w
(L2H)2Ni
(L2H)2Cu
(L2H)2(OH2)2Co 3570 s
3340 s
1660 m 960 s 675 w
L3H2
3280 s
–
–
3050 s
3030 s
3040 s
–
1640 s
1630 s
1650 s
990 s 680 w
960 s 670 w
970 s 675 w
(L3H)2Ni
(L3H)2Cu
1680 m
1690 m
3600 s
(L3H)2(OH2)2Co 3300 s
3050 s
1690 m
1630 m 960 s 685 w
aIn KBr pellets.
s: Strong; m: Medium; w: Weak.

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THIO-p-NITROPHENYLGLYOXIME COMPLEXES
111
O
H
O
O2N
R
N
N
N
N
S
C
C
C
C
M
S
O
H
O
NO2
R
H2O
Trans-Form: M = Ni(II), Cu(II), or
Co(II)
H2O
H....O
O
R
R
N
N
N
N
S
S
C
C
C
C
M
O....H
O
NO2
O2N
H2O
Cis-Form: M = Ni(II), Cu(II), or
Co(II)
H2O
Figure 2. Octahedral and square-planar metal complexes of the unsymmetrical ligands.
ordination (8,9). In the case of Co(II) complexes, the coordinated H2O molecules
are identified by a broad OH absorption around 3270–3600 cm−1 which retains its
intensity even after heating at 100◦C for 24 h under vacuum.
EXPERIMENTAL
All chemicals and the solvents used were of “Analytical Reagent” (Merck)
grade. anti-Chloro(p-nitrophenyl)glyoxime (CPNPGH2) were prepared by re-
ported procedures (12–17). 1H NMR spectra was recorded on a Varian T 100-A

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112
SEVINDIR
spectrometer. IR spectra were recorded on a Pye Unicam SP 1025 spectropho-
tometer as KBr pellets. The elemental analyses were determined in the TUBITAK
Laboratory (Scientific and Technical Research Council of Turkey).
Synthesis of Substituted Thio-p-nitrophenylglyoximes
To a stirred solution of anti-CPNPGH2 (2.436 g, 0.01 mol) in absolute
ethanol (40 mL) at between −10◦ and −15◦C was added dropwise the solution
of 0.01 mol thio compound [thiophenol (0.11 g), 4-methylthiophenol (0.124 g),
4-methoxythiophenol (0.1 mL)] in a mixture of 30 mL of absolute ethanol, and
10 mL of diethyl ether over 30 min in a fume hood. After addition of a 1% NaOH
solution in ethanol to raise the pH to 4–5, the reaction mixture was futhre stirred
for 2 h and then diluted with 120 mL of water and left overnight at 5◦C. The
precipitate was collected by filtration and then recrystallized from ethanol–water
(1:2). The crystalline product was collected, washed with water, and dried at room
temperature.
Synthesis of the Ni(II), Cu(II), and Co(II) Complexes
Solutionsof0.5 mmolofthemetalsalts[NiCl2·6H2O(0.119g), CuCl2·2H2O
(0.086 g) and CoCl2·6H2O (0.119 g)] in 20 mL absolute ethanol were added to
solutions of the ligands (1 mmol) [L1H2 (0.317 g), L2H2 (0.319 g), L3H2 (0.3 mL)]
dissolved in 20 mL of ethanol. The pH of the mixtures dropped to 3.0–3.5 and
the color turned to red-brown. After addition of a 1% ethanolic NaOH solution to
raise the pH to 4.5–5, the mixtures were stirred on a water bath at 50–55◦C for
20 min. The precipitated complexes were collected by filtration while hot, washed
with water, ethanol, and diethylether and dried under vacuum at 100◦C. The yields
and melting points of the compounds are collected in Table 1.
The complexes were soluble in CF3COOH and slightly in hot DMF
and DMSO. Yields: (L1H)2Ni, 0.559 g; (L2H)2Ni, 0.574 g; (L3H)2Ni, 0.600 g;
(L1H)2Cu, 0.625 g; (L2H)2Cu, 0.578 g; (L3H)2Cu, O.642 g; (L1H)2(OH2)2Co,
0.509 g; (L2H)2(OH2)2Co, 0.578 g; (L3H)2(OH2)2Co, 0.629 g.
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Received October 27, 1999
Accepted September 7, 2000
Referee I: K.-H. Dahmen
Referee II: R. A. Faltynek

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