Synthesis and characterization studies of cobalt(II), nickel(II), copper(II) and zinc(II) complexes of carboxymethyl-N-methyl-N-phenyl dithiocarbamate

Article abstract of DOI:10.13005/ojc/340649

Complexes of carboxymethyl-N-methyl-N-phenyl dithiocarbamate (DTC) with cobalt(II), nickel((II), copper(II) and zinc(II) complexes were synthesized in 1:2 molar ratio with general formula [M(DTC)₂],{M=Co(II)/Ni(II)/Cu(II)/Zn(II)} and characteri

Full text of DOI:10.13005/ojc/340649

ISSN: 0970-020 X
CODEN: OJCHEG
018, Vol. 34, No.(6):
Pg. 3064-3069
ORIENTAL JOURNAL OF CHEMISTRY
An International Open Access, Peer Reviewed Research Journal
2
www.orientjchem.org
Synthesis and Characterization Studies of Cobalt(II),
Nickel(II), Copper(II) and Zinc(II) Complexes of
Carboxymethyl-N-Methyl-N-Phenyl Dithiocarbamate
1
2
LEꢀSHMI. V. ꢀUMAR and RATHIꢀA NATH. G *
1
Department of Chemistry, KSM DB College, Sathamcotttah, Kollam – 690521, Kerala, India.
*
Corresponding author E-mail: rakhignath@yahoo.com
http://dx.doi.org/10.13005/ojc/340649
Received: November 05, 2018; Accepted: December 07, 2018)
ABSTRACT
Complexes of carboxymethyl-N-methyl-N-phenyl dithiocarbamate (DTC) with cobalt(II),
nickel((II), copper(II) and zinc(II) complexes were synthesized in 1:2 molar ratio with general formula
[
M(DTC) ],{M=Co(II)/Ni(II)/Cu(II)/Zn(II)} and characterized by elemental analysis, molar conductance,
2
1
13
infrared and electronic spectra.The ligand structure was confirmed by H and C nuclear magnetic
resonance spectrum. The measured molar conductance values indicate the non-electrolytic nature
of the metal complexes. The elemental analysis, infrared, electronic spectra and magnetic moment
suggest that the coordination of DTC occurred through sulphur and oxygen atom as a bidentate.The
cobalt(II) and zinc(II) complexes were found to coordinate in a tetrahedral geometry and complexes
and nickel(II) and copper(II) complexes coordinate in a square planar geometry. Thermal analysis
was carried out to ascertain the thermal stability of the metal complexes. By using powder XRD
measurements, the lattice parameters, space group and grain size were determined.The scanning
electron microscope images reveal the surface morphology of the metal complexes.
INTRODUCTION
additional donor groups such as oxygen and nitrogen
atoms were found to show dramatic changes in their
biological properties . Dithiocarbamate complexes
Sulphur-bonding ligands are important from
7,8
thebiologicalpointofviewandhaveattractedinorganic
of different transition metal ions were reported to
1,2
chemistsinthepastyears .Dithiocarbamatesareoneof
the most important classes of sulphur containing organic
ligands with unpredictable coordination behaviour, self-
assembly with transition element and their applications
9,10
11
act as anticancer , catalytic , and antimicrobial
12,13
activities . Dithiocarbamate complex are widely
used in electro analytical reagents, catalysts and
potential brain perfusion imaging agents . Most
dithiocarbamate complexes are used as nano
precursor for the synthesis of nanoparticles .
The present work is related to the synthesis and
characterization studies of carboxymethyl-N-methyl-
14-16
3,4
in several areas of chemical and biological fields .
Dithiocarbamate act as monodentate, bidentate or
chelating ligand, in which the different binding property
determine the structural organization of coordination
1
7
5
, 6
complex . The dithiocarbamate which contain
This is an
Open Access article licensed under a Creative Commons license: Attribution 4.0 International (CC- BY).
Published by Oriental Scientific Publishing Company © 2018

NATH. G, KꢀMAR., Orient. J. Chem., Vol. 34(6), 3064-3069 (2018)
3065
N-phenyl dithiocarbamate complexes of cobalt(II),
nickel(II), copper(II) and zinc(II).
dried. The purity of the ligand was checked by thin
layer chromatographic technique.
MATERIALS AND METHODS
Preparation of metal complexes
A hot methanolic solution (15 ml) of
the ligand (2 mmol) was added dropwise to a
hot methanolic solution (15 ml) of cobalt/copper/
nickel/ zinc chlorides (1 mmol) and refluxed for
Analar grade solvents and chemicals
were used for this study. Transition metal(II) salts
cobalt/ nickel/ copper and zinc chlorides), carbon
disulfide, N-methyl aniline, sodium hydroxide, sodium
choloroacetate were purchased from Sigma Aldrich
and Merck chemicals. Solvents used for physico-
chemical measurements were purified by standard
methods.
(
0
1 h on a water bath at 70 C. The pH of the solution
was adjusted to ~7- 8 by adding sodium hydroxide
solution and continued the refluxing process for
4 hours. The solid product separated was filtered,
washed successively with methanol, filtered and
dried in vacuum desiccator.The purity was checked
by thin layer chromatographic technique.
Microanalysis(C, H, N, S) was done using
Elementar Vario EL III CHN analyzer.The magnetic
susceptibility measurements were carried out
RESULTS AND DISCUSSION
using Gouy`s method using Hg[Co(SCN) ]used
4
as calibrant. Diamagnetic corrections were made
by using Pascal constants. Molar conductance
The synthesized ligand and its metal(II)
complexes are non-hygroscopic solids, soluble in
DMSO.Analyticaldataoftheligandanditscomplexes
are in good agreement with their formulation, which is
given inTable1.All the complexes possess 1:2 metal
ligand stoichiometry and formulated as [M(DTC)2],
where M= Co(II), Ni(II), Cu(II) or Zn(II), DTC =
Dithiocarbamate. The molar conductance values of
the complexes in 0.001M DMSO solution lies in the
-
3
measurements were done using 10 M solutions of
the complexes in DMSO solvent at room temperature
using digital conductivitymeter. Infrared spectra
of ligand and its complexes were obtained using
potasium bromide pellets in the range of 4000-400
-
1
cm on a Perkin Elmer FT-IR spectrophotometer.
The electronic spectra of the ligand and its
complexes were recorded using Genesys 10S-ꢀV-
VIS spectrophotometer in DMSO solvent.The NMR
spectrum was taken in BRꢀKER Avance –III 300
-
1
2
-1
range of 13-17 Ω cm mol at room temperature.
These values indicate that the complexes were
18
non-electrolytes in nature .
MHz NMR spectrometer, using DMSO- as solvent.
d6
Powder XRD measurements were conducted
1H-NMR spectrum
8
using Bruker D. Advance X-ray diffractometer. The
Proton NMR spectrum of DTC was
thermogravimetric analysis was carried out in the
measured in DMSO-d6 solvent and it’s shown in
the Fig. 1. The multiplet peak obtained at 7.4-8 ppm
corresponds to the peak of aromatic hydrogen atom
0
range of room temperature to 800 C in a Perkin
0
Elmer Diamond TG/DTA at a heating rate of 10 C.
19
Scanning electron microscope was recorded in JEOL
model JSM-6390 LV SEM instrument analyzer.
of phenylgroup . Two singlet peaks were seen at
3.6 ppm and 3.96 ppm is due to the methyl group
attached to nitrogen and methylene group attached
Preparation of carboxymethyl-N-methyl-N-phenyl
dithiocarbamate(DTC)
20
to the carboxy group . A singlet sharp peak at 12.63
ppm is due to the hydrogen atom of carboxylic acid.
A mixture of carbon disulfide (12 mL,
0
.20 mol) and N-methylaniline (21.6 mL, 0.20 mol)
13C-NMR spectrum
was treated with sodium hydroxide (8.2 g, 0.20
mol) dissolved in 250 mL water. The organic layer
disappears after stirring the solution for 4 h at room
temperature.At this point the resulting straw coloured
solution was treated with sodium choloroacetate
The carbon skeleton of the dithiocarbamate
1
3
ligand was identified using C-NMR spectrum.
Carbon attached to the C=S group resonates
2
1
at downfield shift at 196 ppm . The peak at
169 ppm is due to the carbon atom of carboxylic acid.
The carbon atom of the phenyl ring attached to the
aniline nitrogen also resonates at downward shift at
(
23.2 g, 0.20 mol) and allowed to stand for 24 hours.
The resulting solution was acidified with conc. HCl
and the solid which was separated, collected and

NATH. G, KꢀMAR., Orient. J. Chem., Vol. 34(6), 3064-3069 (2018)
3066
1
46 ppm. The downward shift occurs as a result of
attached to the carboxylate group resonate at 46.01
ppm. The other carbon atoms of the benzene ring
were assigned to signal at 129.5 ppm (ortho), 127.08
22
the deshielding from the neighbouring nitrogen atom .
The carbon atom of methyl group attached to the
nitrogenresonatesat41.89ppmandmethylenegroup
23
ppm(meta), 126.92(para) ppm respectively.
Table1: Physical and analytical data of ligand and its complexes
Ligand/
Complexes
Yield (%) Colour Melting Empirical Formula
Mol.
Weight
Elemental Analyses(%)
Cal. (Found)
O
point ( C)
C
H
N
S
DTC
81
Off white
122
C H NO S2
241
49.77 4.59
5.8
26,57
1
0
11
2
4
9.71 4.56 5.74 26.49
44.52 3.74 5.19 23.77
4.48 3.71 5.12 23.64
44.54 3.74 5.19 23.78
4.49 3.69 5.12 23.73
44.14 3.7 5.15 23.57
4.04 3.64 5.11 23.49
43.99 3.69 5.13 23.49
3.74 3.48 5.08 23.43
[Co(DTC)2]
[Ni(DTC)2]
[Cu(DTC)2]
[Zn(DTC)2]
72 Pale Green 156
C H CoN O S
539.58
539.34
544.19
546.02
16
22
2
4
4
4
81
74
79
Green
Green
White
194
178
168
C H NiN O S
20 20 2 4 4
4
C H CuN O S
20
20
2
4
4
4
C H ZnN O S
20
20
2
4
4
4
-1
range of 1660-1600 cm of complex indicate that
carboxylate ion is coordinated towards the central
metal atom. IR spectrum also exhibits characteristic
-1
bands of carboxylate anion at 1591 cm (asymmetric
-1
stretching) and at 1415 cm (symmetric stretching) in
-1
copper complex, at 1589 cm (asymmetric stretching)
-1
and at 1412 cm (symmetric stretching) in cobalt
-1
complex, at 1596 cm (asymmetric stretching) and at
-
1
1
395 cm (symmetricstretching)innickelcomplexand
-1
-1
at 1584 cm (asymmetric stretching) and at 1396 cm
symmetric stretching) in zinc complex.The difference
(
Fig. 1. Proton NMR spectrum of DTC
between the symmetric and asymmetric stretching
peaks indicates the coordination of carboxylate ion
24
towards the metal ions .The strong band observed at
-1
8
75 cm assigned for C=S stretching frequency in the
spectrum of ligand, which is shifted towards to lower
frequency indicates the coordination of the sulphur to
the metal atom.The additional bands in the range of
-
1
-1
4
20-435 cm and 560-580 cm indicate the presence
25,26
of M-S and M-O bonds .The infrared spectrum of
ligand and its complexes are shown in the Figurs 3.
Fig. 2. 13C-NMR spectrum of DTC
Infrared Spectra
The IR spectra of the ligand and its
complexes were used to identify the coordination
behaviour of ligand towards the central metal atom.
A broad frequency band in between 2910-2920
-
1
cm in the free ligand indicates the presence of
OH group. The characteristic absorption peak of
-1
carboxylic acid of the dithiocarbamate at 1664 cm
was found to present, but the absence of peak in the
Fig. 3. FTIR spectrum of ligand and complexes

NATH. G, KꢀMAR., Orient. J. Chem., Vol. 34(6), 3064-3069 (2018)
Electronic spectra and magnetic moment
3067
The electronic absorption band of ligand
and complexes were recorded in DMSO solvent
o
at 25 C. Electronic spectral peak of the complexes
around 300nm is attributed to intra ligand transition.
The electronic spectrum of ligand exhibits two peaks
at 276 nm and 324 nm, which may be assigned to
27
be due to π-π* and n-π* transitions .
Fig. 4a. Structure of DTC\
The copper(II) complex possess the
absorption bands at 281 nm and 329 nm is
due to intra ligand π-π* and n-π* transitions.
For square planar complexes, three allowed
transitions are usually found. But since four d
orbitals are very close to each other, it was difficult to
distinguish three bands and a broad band appears at
680-720 nm corresponding to the d-d transitions of
the copper(II) complex.A band due to ligand to metal
charge transfer occurs at 470-520 nm.The magnetic
moment of copper(II) complex was found to be 1.72
BM, which is due to the presence of one unpaired
electron. From the spectral and magnetic moment
studies suggest a square planar environment of
Fig. 4b. Structure of metal complexes
Thermogravimetric Analysis
The thermal decomposition pattern and
thermal stability of the metal complexes were
analysed using thermogravimetric studies (Fig. 5).
28, 29
copper complex
.
o
The absence of weight loss upto 200 C confirms the
The magnetic moment of cobalt(II) complex
is 4.32 BM. An absorption band at 630 nm assigned
to be ligand to metal charge transfer and the green
colour of the complex are strong evidences to support
34
absence of water molecule in the solid form . The
graph shows a three stage decomposition pattern.
First stage decomposition may be due to the loss of
phenyl group and the second stage decomposition
30,31
a tetrahedral geometry for the cobalt complex
.
o
above 230 C may be due to the loss of methyl group.
The subsequent decomposition was found completed
Nickel(II) complex possess the absorption
bands at 282 nm, 331 nm and 440-450 nm.
The intensity and position of the bands and the
diamagnetic character indicates that nickel(II)
complex has square planar geometry around the
o
at 700 C, producing metal residue as the product.
32
central metal atom .
The diamagnetic mononuclear zinc(II)
complex had only intra ligand transition at 280
nm and 336 nm, with a mononuclear tetrahedral
33
geometry around the central metal atom .
From the above studies, the complexes
could be formulated as [M(DTC) ]. On the basis of
2
Fig. 5.Thermogravimetric analysis of complexes a) cobalt(II)
b) nickel(II) c) copper(II), and d) zinc(II) complexes
the previously discussed physico-chemical values
and spectral data, the structure of the ligand and
complexes could be assigned as shown in the
Figurs 4a and 4b.
Powder XRD Analysis
The powder X-ray diffraction patterns

NATH. G, KꢀMAR., Orient. J. Chem., Vol. 34(6), 3064-3069 (2018)
3068
0
were recorded in the range of 2θ = 5 to 80 . Sharp
crystallinepeakswereobservedinthemetalcomplexes,
indicating the crystalline behaviour as shown in the Fig.6.
Theaveragegrainsizeofthecomplexeswerecalculated
20.1 nm and 19.1 nm respectively indicate that the
metalcomplexesareinnanosize.PowderXRDpatterns
clearly indicate that copper(II) and nickel(II) complexes
have crystalline behaviour . The lattice parameter,
space group, and crystal system of complexes were
determined and the details are given in Table 2.
37
35,36
using debye scherer equation
as dXRD= 0.9λ/βcosθ.
Thegrainsizeofthenickel(II)andzinc(II)complexeswere
Table 2: PXRD data of the copper(II) and zinc(II) complexes
Complex Lattice constant parameters(Å) Inter Axial
Space
group
Crystal
system
a
b
C
Angle
[
[
Cu(DTC)2]
Zn(DTC)2]
9.21
6.53
14.49 19.98 α=γ=90, β ≠90 c2/m
11.47 12.32 α=γ=90, β ≠90 P21/c
Monoclinic
Monoclinic
CONCLUSION
We prepared cobalt, nickel, copper and
zinc complexes of carboxymethyl N-methyl N- phenyl
dithiocarbamate and characterized using elemental
analysis, magnetic moment, molar conductance,
IR and electronic spectrum. The results clearly
demonstrates that the ligand coordinates towards the
central metal ion in a bidentate mode, and the cobalt
and zinc complexes have a tetrahedral geometry
while copper and nickel complexes have square
planar geometry. The molar conductance values
indicate the nonelectrolytic nature of complexes.
The thermogravimetric analysis indicates that the
Fig. 6. PXRD patterns of metal complexes
Sem analysis
Thesurfacemorphologyofmetalcomplexes
was analyzed using scanning electron microscope,
and is shown in the Fig.6.PXRD results also suggest
nanosize for copper(II) and zinc(II) complexes.SEM
images with magnification value of 7,000X and
optimum energy value of 20 kv were used for the
analysis. SEM micrograph indicates cluster plate,
cauli-flower, rose petal and agglomerated cluster
like morphological structures for the cobalt, copper,
0
complexes were stable upto 200 C. The complexes
were found to possess crystal size less than
20.1 nm, which increases the possibility of their use
as nano precursors. XRD analysis shows Cobalt(II)
and nickel(II) complex were found to be amorphous,
copper(II) and zinc(II) complex were crystalline in
nature. Surface morphology of the complexes were
also analysed using SEM.
38
nickel and zinc complexes .
ACꢀNOWLEDGEMENT
Authors are thankful to STIC, CꢀSAT, Kochi
for the instrumental analysis of samples and SICC,
ꢀniversity of Kerala, Thiruvananthapuram for PXRD
analysis. One of the author (Lekshmi V Kumar)
acknowledge the CSIR, New Delhi for the financial
support through the grant no. 08/537(0004)/2014
EMR-1, dated 27/08/2014.
Fig. 7. SEM images of complexes

NATH. G, KꢀMAR., Orient. J. Chem., Vol. 34(6), 3064-3069 (2018)
3069
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