Synthesis, spectral, crystal structures, Hirshfeld surface analysis and DFT studies on bis(N,N-di(4-methoxybenzyl)dithiocarbamato-S,S′)zinc(II) and its imine adducts: new precursor for the preparation of hexagonal ZnS

Article abstract of DOI:10.1080/17415993.2017.1340477

[Zn(4-mbzdtc)₂] (1), [Zn(4-mbzdtc)₂(py)] (2), [Zn₂(4-mbzdtc)₄(4,4′-bipy)] (3), and [Zn(4-mbzdtc)₂(2,2′-bipy)] (4), (where, 4-mbzdtc = N,N-di(4-methoxybenzyl)dithiocarbamate) were prepared and characte

Full text of DOI:10.1080/17415993.2017.1340477

Journal of Sulfur Chemistry
ISSN: 1741-5993 (Print) 1741-6000 (Online) Journal homepage: http://www.tandfonline.com/loi/gsrp20
Synthesis, spectral, crystal structures, Hirshfeld
surface analysis and DFT studies on bis(N,N-
di(4-methoxybenzyl)dithiocarbamato-S,S′)zinc(II)
and its imine adducts: new precursor for the
preparation of hexagonal ZnS
Pandurangan Selvaganapathi, Subbiah Thirumaran & Samuele Ciattini
To cite this article: Pandurangan Selvaganapathi, Subbiah Thirumaran & Samuele Ciattini (2017):
Synthesis, spectral, crystal structures, Hirshfeld surface analysis and DFT studies on bis(N,N-
di(4-methoxybenzyl)dithiocarbamato-S,S′)zinc(II) and its imine adducts: new precursor for the
preparation of hexagonal ZnS, Journal of Sulfur Chemistry, DOI: 10.1080/17415993.2017.1340477
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Date: 27 June 2017, At: 20:50

JOURNAL OF SULFUR CHEMISTRY, 2017
https://doi.org/10.1080/17415993.2017.1340477
Synthesis, spectral, crystal structures, Hirshfeld surface
analysis and DFT studies on
ꢀ
bis(N,N-di(4-methoxybenzyl)dithiocarbamato-S,S )zinc(II)
and its imine adducts: new precursor for the
preparation of hexagonal ZnS
a
a
b
Pandurangan Selvaganapathi , Subbiah Thirumaran and Samuele Ciattini
a
b
Department of Chemistry, Annamalai University, Annamalinagar, India; Centro di Cristallografia Strutturale,
Polo Scientifio di Sesto Fiorentino, Firenze, Italy
ABSTRACT
ARTICLE HISTORY
Received 25 March 2017
Accepted 2 June 2017
ꢀ
[
Zn(4-mbzdtc)2] (1), [Zn(4-mbzdtc)2(py)] (2), [Zn2(4-mbzdtc)4(4,4 -
ꢀ
bipy)] (3), and [Zn(4-mbzdtc)2(2,2 -bipy)] (4), (where, 4-mbzdtc = N,
N-di(4-methoxybenzyl)dithiocarbamate) were prepared and charac-
KEYWORDS
1
13
terized by elemental analysis, infrared, H and C NMR spectroscopy
and the structures of 1 and 3 were elucidated by X-ray crystallog-
raphy. The monomeric structure of 1 shows a distorted tetrahedral
geometry for zinc(II). The coordination geometry around zinc in din-
uclear complex 3 is an intermediate between square pyramidal and
trigonal bipyramidal. The downfield shift of NCS2 carbon signal for
imine adducts of 2–4 compared to those found in parent complex
Zinc(II) dithiocarbamate;
imine adducts; single source
precursor; zinc sulfide
nanoparticles; Hirshfeld
surface analysis
1
is attributed to the change in coordination number and steric
effect exerted by the nitrogen donor ligand. Hirshfeld surface anal-
ysis was used to visualize intermolecular interactions in the crystal
structure of 1 and 3. The geometry optimization of 1 is performed
using DFT with the B3LYP-LANL2DZ basis set. Solvothermal decom-
position of 1 yielded only hexagonal zinc sulfide nanoparticles. Zinc
sulfide nanoparticles were characterized using powder X-ray diffrac-
tion, scanning electron microscopy, energy dispersive X-ray spec-
tra and diffuse reflectance spectra. DRS study of ZnS nanoparticles
shows the quantum confinement effect with a band gap of 3.74 eV.
CONTACT Subbiah Thirumaran
sthirumaran@yahoo.com
Department of Chemistry, Annamalai University,
Annamalainagar 608 002, Tamil Nadu, India
This article makes reference to supplementary material available on the publisher’s website at https://doi.org/10.1080/
7415993.2017.1340477.
1
©
2017 Informa UK Limited, trading as Taylor & Francis Group

2
P. SELVAGANAPATHI ET AL.
1. Introduction
Dithiocarbamates are highly versatile ligands forming stable metal complexes with wide
range of applications, including use as rubber vulcanization accelerators [1], catalysis [2],
antioxidants/antiabrasives in motor oils [3–5], pesticides [6] and fungicides [7]. The solid
state structural chemistry of the group 12 dithiolates is fascinating in that 12 motifs rang-
ing from monomeric, dimeric, tetrameric and linear polymeric, layer to three-dimensional
network architectures [8]. Zinc(II) bis(dithiocarbamate) complexes have been stabilized by
C−H···X (X=O, N), C−H···π, π···π and C−H···π (MS C ring) interactions resulting
2
supramolecular networks [9,10] in the solid state. A developing interest in these com-
plexes mainly stems from the functionalisation that can be varied on the N-bound organic
moiety of dithiocarbamates which allows structural diversity and influences the physico-
chemical properties of their complexes [11,12]. Recently, monomeric and dimeric zinc(II)
complexes containing pyridyl-functionalized dithiocarbamates have been reported [10].
Interest in zinc coordination complexes containing pyridine moieties arises from their
potential use as luminescent materials [13]. Zinc sulfide, a direct band gap semiconduc-
tor with band gap energy of 3.68 eV, is one of the most important materials in photonic
research [14,15]. A number of zinc dithiocarbamate complexes have been used as sin-
gle source precursors for the preparation of ZnS nanopowders [16–18] and thinfilms [19]
by varying the precursors and reaction conditions such as the reaction temperature, reac-
tion time and solvent affect the phase, size and shape of the nanoparticles [20–23]. Here,
ꢀ
the synthesis of bis(di-(4-methoxybenzyldithiocarbamato-S,S )zinc(II), its adducts of pyri-
ꢀ
ꢀ
dine, 4,4 -bipyridine and 2,2 -bipyridine and zinc sulfide nanoparticles from complex 1 and
their characterization is reported. In addition, crystal structures, Hirshfeld surface analysis
and DFT studies on complexes 1 and 3 are also presented.
2
. Results and discussion
.1. Spectral studies
The characteristic infrared (IR) spectral bands that are sensitive to molecular structure of
2
metal dithiocarbamate are the stretching modes for the v
spectra of complexes 1–4 exhibit distinct vibrational bands in the region 1450–1550 cm
and v
bands. The IR
C−N
C−S
−
1
,
which reveal that a considerable partial double bond character of the C−N bond in the
dithiocarbamate ligands. The single C−S asymmetric stretching bands observed in the
−1
region 950–1050 cm for all four complexes indicate bidentate coordination modes for

JOURNAL OF SULFUR CHEMISTRY
3
the dithiocarbamate ligands. UV–VIS spectra of complexes 1–4 show two bands around
38 and 280, which are assigned to a ligand centered (LC) π–π* transitions within the lig-
2
1
0
and. No transitions are observed in the visible region, consistent with the d configuration
of the Zn(II) ion [24].
1
In the H NMR spectra, the methyl and methylene group protons of complexes 1–4 dis-
played a normal single signal around 3.83 and 5.04 ppm. The aromatic protons appeared
1
3
in the region 6.85–7.33 ppm. The N CS carbon signal in all the complexes gave a sin-
2
1
3
gle signal in the region 205.0–208.0 ppm. The N CS chemical shifts follow the order: 1
2
(
205.0 ppm) < 2 (206.3 ppm) ≈ 3 (206.0 ppm) < 4 (207.8 ppm). Additional coordination
of nitrogen donor ligands increases the electron density on zinc. This decreases the C−N
1
3
partial double bond character in complexes 2–4. The downfield shift of N CS carbon
2
signal for 4 from the chemical shift values of 2 and 3 is due to the increasing coordination
number from 5 to 6. The signals of methyl and methylene carbons appeared around 55.3
and 55.0 ppm, respectively, for all the complexes. Aromatic carbon signals are observed in
the region 114.0–130.0 ppm.
2.2. Single-crystal X-ray structural analysis
2.2.1. Structural analysis of complex 1
The ORTEP diagram of 1 is shown in Figure 1. Selected bond distances and angles are given
in Table S2 (http://dx.doi.org/10.1080/17415993.2017.1340477). Geometric details of
hydrogen bonding in complexes are listed in Table S3 (http://dx.doi.org/10.1080/17415993.
2
017.1340477). The molecular structure of 1 is monomeric with zinc(II) coordinated
to four sulfur atoms of two bidentate chelating dithiocarbamate ligands. The coordi-
nation geometry about the zinc atom is a highly distorted tetrahedron with S−Zn−S
bond angles ranging from 78.398(19)° to 131.49(2)°. The distortion index is defined
ꢀ
as τ = −0.00709α−0.00709β + 2.55 and τ = −0.00399α − 0.01019β + 2.55, where α
4
4
and β are the two largest angles. For complex 1, α = 122.79° and β = 131.49°. The
ꢀ
τ and τ values for perfect square planar and tetrahedral are 0 and 1. The τ and
4
4
4
(
a)
(b)
Figure 1. ORTEP diagrams of complexes (a) 1 and (b) 3. Displacement ellipsoids are drawn for 1 and 3
at 30% and 50% probability levels, respectively.

4
P. SELVAGANAPATHI ET AL.
ꢀ
τ values of complex 1 are 0.71 and 0.70. This reveals that the coordination geometry
4
around zinc is a distorted tetrahedral geometry. This distortion arises from the small
bite angle of chelating dithiocarbamate ligands. The four zinc-sulfur distances are in the
ꢀ
range from 2.3232(6) Å to 2.3507(6) Å. The S,S -isobidentate coordination mode of dithio-
carbamate ligand leads to the formation of four membered chelate rings(ZnS C). The
2
ZnS CN atoms are nearly coplanar. There are four C−H···π interactions observed (Fig-
2
ures S1–S3 (http://dx.doi.org/10.1080/17415993.2017.1340477). The methoxy groups in 1
are involved in linking the zinc dithiocarbamate entities. The chains are formed by weak
C−H···O hydrogen bonds (Figure S4 (http://dx.doi.org/10.1080/17415993.2017.1340477).
An intermolecular C−H···S interaction occurs between H33 and S1 (Figure S5
(http://dx.doi.org/10.1080/17415993.2017.1340477).
2.2.2. Structural analysis of 3
ORTEP diagram of 3 is displayed in Figure 1 and the selected geometric param-
eters are given Table S2 (http://dx.doi.org/10.1080/17415993.2017.1340477). The two
ꢀ
bis(N,N-di(4-methoxybenzyl)dithiocarbamato-S,S )zinc(II) molecules are bridged by a
4
ꢀ
,4 -bipyridine ligand. The zinc atoms are five coordinate and the five coordination
atoms come from asymmetrical coordinating four sulfur atoms of two dithiocarba-
ꢀ
mate ligand and a nitrogen atom of 4,4 -bipyridine. The coordination geometry can be
described as an intermediate geometry between square pyramidal and trigonal bipyra-
midal with τ being 0.71 for Zn1 and 0.55 for Zn2, which compares with τ = 0.00 for
an ideal square pyramid and τ = 1.0 for perfect trigonal bipyramid [25]. When con-
sidering the coordination geometry of Zn1 and Zn2 as distorted square pyramidal,
the equatorial plane is defined by the three sulfur atoms (S1–S3 for Zn1 and S5–S7
ꢀ
for Zn2) from dithiocarbamate ligands and one N atom of 4,4 -bipyridine, while the
axial position is occupied by a sulfur atom (S4 and S8 for Zn1 and Zn2, respectively).
The dithiocarbamate ligands are anisobidentatically chelated to Zn, with one long and
one short Zn−S bond (mean: 2.3455(6) and 2.5498(6) Å, respectively). These bond
ꢀ
lengths are comparable with the values observed in previously reported [Zn(dtc) (4,4 -
2
bipy)] [26]. Molecules pack through a C−H···π(chelate) interactions between the din-
uclear molecules (Figure S6 (http://dx.doi.org/10.1080/17415993.2017.1340477). Inter-
molecular C−H···S interactions lead to the formation of the polymer (Figures S7–S9
(http://dx.doi.org/10.1080/17415993.2017.1340477).
In both the complexes, the C−S bond lengths are in the range 1.711(3)–1.735(3) Å
which are shorter than the typical C−S single bond length due to partial π-conjugation
over the N−C−S group. The stronger C−N (thioureide) bonds (1.333(3)–1.336(3) Å)
reflect the contribution of double bond to the formally ordinary single bond (due to the
2
3
mixing of the sp and sp states of the nitrogen atom). The Zn−S distances in 1 and 3 are
symmetric and asymmetric, respectively. Of the two sets of Zn−S distances observed in
3
, the shorter ones are close to those observed in 1. However, other set of distances is sig-
nificantly longer than the corresponding distances observed in 1. A significant increase in
Zn−S distances in complex 3 compared to the parent complex 1 (mean: 2.3395(6) Å and
2
.4475(7) Å for 1 and 3, respectively) is observed. The S−Zn−S site angles in 3 are less than
those in 1. There is a slight decrease in C−S bond distances compared to those in 1. These
ꢀ
are due to the increase in coordination number and steric nature of 4,4 -bipyridine ligand

JOURNAL OF SULFUR CHEMISTRY
5
coordinated to the zinc ions. The other bond distances and angles related dithiocarbamate
moiety remain almost unaltered.
2
.3. Hirshfeld surface analysis
The molecular Hirshfeld surface (dnorm, shape index and curvedness) of 1 and 3 is
shown in Figure S10 (http://dx.doi.org/10.1080/17415993.2017.1340477). The shape index
is highly sensitive to very subtle changes in the surface shape. The information con-
veyed by the shape index are consistent with 2D fingerprint plots. The flat areas of the
surface correspond to low values of curvedness (Figure S10 (http://dx.doi.org/10.1080/
1
7415993.2017.1340477), whereas sharp curvature areas correspond to high values of
curvedness and usually tend to divide the surface into particles, indicating interactions
between neighboring molecules. The 2D fingerprint plot is formed by the combination of
the distances from the Hirshfeld surface to the nearest nucleus inside the surface (d ) and
i
outside the surface (d ). When d
is mapped, close intermolecular distances are char-
e
norm
acterized by two identically colored regions, red (i.e. distances shorter than sum of van
der Waals radii) through white to blue (i.e. distances longer than sum of van der Waals
radii) [27]. The relative contribution of different atom···atom contacts is given in Figure
S11 (http://dx.doi.org/10.1080/17415993.2017.1340477). The fingerprint plots of 1 and 3
are displayed in Figures S12 and S13 (http://dx.doi.org/10.1080/17415993.2017.1340477).
The finger print plots of 1 and 3 show that H···H (42.40% and 44.40% for 1 and 3) and C···H
(24.50% and 23.20% for 1 and 3) interactions are the main intermolecular interactions.
Thus, these interactions exhibit the most significant contributions to the total Hirshfeld
surface. The percentage of C···H, S···H and O···H interaction contributions to the total
Hirshfeld surface for 1 is greater than those of 3.
2.4. DFT studies on 1
2.4.1. Optimized geometry
The comparison of the geometric parameters of the optimized structure and the XRD data
of 1 is listed in Table S2 (http://dx.doi.org/10.1080/17415993.2017.1340477). The theoret-
ical bond lengths are slightly longer and bond angles are slightly less than those of XRD
data. The small discrepancies in bond parameters are due to the fact that theoretical calcu-
lations belong to isolated molecule in the gaseous phase and the XRD data results belong
to molecules in the solid state, where the packing effects and intermolecular interactions
play an important role in keeping molecules together.
2.4.2. HOMO–LUMO energy gap
The frontier molecular orbitals, energy of HOMO and LUMO as well as the difference in
energy between the HOMO and LUMO have been calculated. The HOMO–LUMO energy
gap is a reactivity index, a large gap indicates less reactivity of the molecule and vice versa
[
28]. Frontier molecular orbitals and their energies are given in Figure 2. The energy gap
between HOMO and LUMO of 1 is equal to 4.9610 eV. This energy gap is similar to those
reported for bis(N-furfuryl-N-(4-chlorobenzyl)dithiocarbamato-S,S )zinc(II) (4.2884 eV)
and bis(N-furfuryl-N-(4-methoxybenzyl)dithiocarbamato-S.S )zinc(II) (4.9800 eV) [29].
ꢀ
ꢀ
Figure 2 exhibits that the HOMO spreads over all atoms of one of the dithiocarbamate

6
P. SELVAGANAPATHI ET AL.
(
a)
(b)
Figure 2. Frontier molecular orbital pictures of 1: (a) HOMO and (b) LUMO).
ligands except C of NCS and two sulfur atoms of another dithiocarbamate ligand, whereas
2
the LUMO is located mostly on NCS moiety and partly on phenyl ring of one of the
2
dithiocarbamate ligand. Using the HOMO and LUMO energy values, the following chem-
ical reactivity [30] descriptors have been calculated. The calculated chemical hardness (η),
chemical potential (μ) and electrophilicity (ω), for 1 are 2.4803, −3.5770, and 2.5792 eV,
respectively. The negative value of chemical potential indicates the high stability of the
complex 1.
2.4.3. Molecular electrostatic potential
The molecular electrostatic potential (MEP) map gives one of the most useful electro-
static properties to examine the structure and activity. A MEP surface map of 1 is shown
in Figure S14 (http://dx.doi.org/10.1080/17415993.2017.1340477). Generally, electrophilic
and nucleophilic reactions occur easily in the most positive and negative region of MEP,
respectively. The MEP map of complex 1 shows that hydrogen atoms of methyl and phenyl
groups have low electron densities and the electrostatic potentials near these regions are
positive. The electron densities are very high at all the S atoms of NCS groups and O atoms
2
of the methoxy group (red region). The electrostatic potentials near these red regions are
negative.
2
.5. Characterization of zinc sulfide
The phase of as-prepared ZnS was studied by X-ray diffraction (XRD) analysis. The
powder XRD patterns of ZnS are shown in Figure 3. All the peaks of the XRD pat-
tern can be indexed to a hexagonal phase of ZnS. No peaks for other phases of ZnS
are observed in the XRD pattern, indicating the presence of single phase. The morphol-
ogy of the as-prepared ZnS was analysed by SEM (Figure S15 (http://dx.doi.org/10.1080/
1
7415993.2017.1340477). The SEM image reveals that the irregular particles are an aggre-
gation of a large number of spherical shaped nanoparticles which can be attributed
to the extremely small dimensions and high surface energy of the nanoparticles. The
formation of zinc sulfide was confirmed using energy-dispersive X-ray spectral (EDS)

JOURNAL OF SULFUR CHEMISTRY
7
Figure 3. PXRD patterns of as-prepared ZnS.
analysis. Energy-dispersive X-ray spectrum of as-prepared ZnS is given in Figure
S16 (http://dx.doi.org/10.1080/17415993.2017.1340477). The atomic ratio of Zn/S is
5
0.21:49.79, respectively. This supported the formation ZnS. Diffuse reflectance spectrum
of as-prepared ZnS was recorded to resolve the excitonic or in their band valence – conduc-
tion band transitions of ZnS, which is also used to determine the band gap. The absorption
edge of as-prepared ZnS (320 nm) is blue shifted from the absorption edge of bulk ZnS
3
45 nm [31]. The band gap energy of the samples is measured by the extrapolation of the
2
linear portion of the graph between the modified Kubelka–Munk function [F(R)hv] ver-
sus photon energy (hv) (Figure S17 (http://dx.doi.org/10.1080/17415993.2017.1340477)
[
32]. The calculated band gap of as-prepared ZnS is 3.74 eV. This indicates the presence
of quantum size effect in the as-prepared ZnS nanoparticles.
3. Conclusions
Complexes 1–4 were synthesized and characterized. Crystal structures of 1 and 3 are
mononuclear and dinuclear, respectively. The coordination geometry around Zn(II) in 1
is a distorted tetrahedral, whereas the coordination geometry of both Zn(II) in ions in the
dinuclear complex 3 is described as distorted square pyramid. All interactions in crystal
structures of 1 and 3 have been also studied by Hirshfeld surface analysis. Crystal structure
analysis supported with the Hirshfeld surface and fingerprint plots enabled the identifi-
cation of the significant intermolecular interactions. The overall fingerprint plots help to
distinguish the differences in the crystal packing by 1 and 3 as well as to understand the
contributions of different type of contacts present. The MEP map of 1 predicts that the S
and O atoms of 1 are the most reactive which clearly indicates the propensity of the sites
for the formation of intermolecular interactions with potential electronic-rich sites. Com-
plex 1 was effective as single source molecular precursor for ZnS nanoparticles. The SEM
image of as-prepared ZnS reveals that the particles are spherical.

8
P. SELVAGANAPATHI ET AL.
4. Experimental
4
.1. Materials and methods
All reagents and solvents were used without further purification and all experiments were
carried out in atmospheric air. Melting points were determined by an electro-thermal melt-
ing point apparatus and are uncorrected. Microanalysis for carbon, hydrogen and nitrogen
in the synthesized complexes was done on an Elementar model Vario MICRO V2.2.0. IR
1
13
spectra were recorded on a Perkin Elmer FT-IR spectrometer. The H NMR and C NMR
spectra were recorded on Bruker 400 MHz spectrometer at room temperature in CDCl3
as a solvent, using TMS as an internal standard. The powder XRD were recorded using
inel EQUINX 1000 and the SEM and EDS were obtained in a JEOL-JSM-6610 and INCA
energy software. SHIMADZU UV-1650 PC double beam UV–VIS spectrophotometer was
used for recording the electronic spectra of the complexes. Diffuse reflectance spectrum
was recorded using a SHIMADZU UV-2600 UV–VIS spectrometer.
4
.2. X-ray crystallography
Single crystal XRD data for complexes 1 and 3 were performed on an Xcalibur, Sap-
phire3 (CuKα radiation (λ = 1.54184 Å)), and Xcalibur, Sapphire3 (MoKα radiation
(
λ = 0.71073 Å), respectively, diffractometer using graphite-monochromated at an ambi-
ent temperature. The structure was solved and refined by direct method using SHELXL-
2
refined anisotropically and the hydrogen atoms were refined isotropically. The model for
the refinement of hydrogen atoms is constrained. The C11–C17 and O2 atoms in complex
014/7 [33]. All the non-hydrogen atoms except C11−C17 and O2 in complex 3 were
3
were disordered over two positions with the major component having a site occupancy
factor of 0.568(6). Choloroform, acetonitrile and water molecules are cocrystallized with
complex 3 and disordered over two positions. The major component has a site occupancy
factor of 0.7. The H atoms were not included in the solvent molecules. Details of the data
collection, crystal data and structure refinement parameters for complex 1 and 3 are given
in Table S1 (http://dx.doi.org/10.1080/17415993.2017.1340477). Crystallographic data for
the structures reported in this paper have been deposited with the Cambridge Crystallo-
graphic Data Centre as supplementary publication numbers of CCDC No – 1540119 and
1
540121 for 1 and 3, respectively.
4.3. Computational details
DFT studies were performed with GAUSSIAN-03 program package with the aid of Gauss
view program. Molecular geometries were optimized with DFT using the B3LYP calcula-
tion method and LANL2DZ basic set [34].
4.4. Hirshfeld surface
Hirshfeld surface and 2D fingerprint calculations were performed using the Crystal
Explorer package ver.3.1 [35]. Crystal structures were imported from CIF files. Hirshfeld
surfaces were generated for the complex molecules using a high surface resolution and
mapped with the dnorm or shape index functions. 2D fingerprint plots were prepared with
the use of the same software.

JOURNAL OF SULFUR CHEMISTRY
9
4.5. Synthesis of zinc(II)dithiocarbamate complexes
4
.5.1. Preparation of complex 1
ꢀ
N,N -di-(4-methoxybenzyl)amine was prepared by the methods reported earlier [36].
N,N -di-(4-methoxybenzyl)amine (4.0 mmol) in ethanol was mixed with carbon disul-
ꢀ
fide (4.0 mmol) under ice cold condition. To the resultant yellow dithiocarbamic acid
solution, ZnSO ·7H O (4.0 mmol) was added with constant stirring. The colorless pre-
4
2
cipitate was washed with diethyl ether and then dried. Complex was recrystallized from
chloroform: acetonitrile(1:1) (Scheme 1). Yield: 82%, m.p. 158–160°C. Anal. Calc for
H3CO
NH2
CH OH
3
+
H3CO
OCH3
O
H
N
H CO
3
NaBH4 CH OH : CH Cl
2
3
2
H CO
OCH3
3
N
H
N
(
i) CS2-C2H5OH
(ii) ZnSO4 . 7H2O
OCH3
H CO
OCH3
3
S
S
S
S
N
Zn
N
OCH3
H3CO
H3CO
OCH3
2
pyridine
S
S
S
S
OCH3
OCH3
N
Zn
N
S
S
N
Zn
N
N
1
S
S
H CO
3
4
,4'-bipyridine OCH3
OCH3
2
,2'-bipyridine
N
H CO
OCH3
OCH3
3
S
S
Zn
N
N
S
S
H3CO
3
N
S
N
H CO
OCH3
3
S
Zn
N
N
S
S
OCH3
H3CO
4
Scheme 1. Preparation of complexes 1–4.

10
P. SELVAGANAPATHI ET AL.
C H N O S Zn (730.30): C, 55.92; H, 4.97; N, 3.84; Found: C, 55.77; H, 4.93; N,
3
4
36
2
4 4
−1
3
.80; IR (KBr, cm ): 1512 (ν
), 1032 (ν
). UV–VIS (CH Cl , nm): λ = 238, 276.
C−N
C−S
2
2
1
H NMR (400.00 MHz, CDCl , ppm): 3.83 (s, 12H, 4CH O−C H −CH −N); 4.97 (s,
3
3
6
4
2
1
3
1
8
H, 4OCH −C H −CH −N); 6.91–7.31 (aromatic protons). C { H} NMR (100 MHz,
3
6
4
2
CDCl , ppm): 54.8 (4CH O−C H −CH −N); 55.4 (4CH O−C H −CH −N); 114.3,
3
3
6
4
2
3
6
4
2
1
26.6, and 129.6 (other aromatic carbons); 159.6, (4CH O−Ar); 205.0 (NCS ).
3
2
4.5.2. Preparation of complex 2
Complex 1 (1.0 mmol) was dissolved in 50 ml of warm pyridine. The yellow solution
obtained was filtered and kept for evaporation. After few days, yellow solid separated
out. The precipitate was filtered and dried (Scheme 1). Yield: 58%; m.p.146–148°C. Anal.
Calc for C H N O S Zn (807.13): C, 57.87; H, 5.11; N, 5.19; Found: C, 57.62; H, 5.12;
3
9
41
3
4 4
−
1
N, 5.16; IR (KBr, cm ): 1511(ν
), 1035, (ν
). UV–VIS (CH Cl , nm): λ = 238,
C−N
C−S
2
2
1
2
(
(
77. H NMR (400.00 MHz, CDCl , ppm): 3.83 (s, 12H, 4CH O−C H −CH −N); 5.03
3
3
6
4
2
s, 8H, 4OCH −C H −CH −N); 6.90−7.32 (aromatic protons of dithiocarbamate)7.47
3
6
4
2
t, 2H, J = 6.4 Hz, H–3 (py)); 7.85 (t, J = 8.0, 1H, H–4 (py)); 8.95 (d, 2H, J = 4.0 Hz,
1
3
1
H–2 (py));. C { H} NMR (100 MHz, CDCl , ppm): 54.9 (4CH O−C H −CH −N); 55.4
3
3
6
4
2
(
(
2
4CH O−C H −CH −N); 114.0, 114.2, 127.3, and 129.6 (other aromatic carbons); 159.4,
3
6
4
2
4CH O−Ar); 124.5 (C-3 (py)); 137.8 (C-4 (py)); 149.6 (C-2(py)); 159.4, (4CH O−Ar);
3
3
06.3 (NCS ).
2
4
.5.3. Preparation of complex 3
ꢀ
A hot solution of 4,4 -bipyridine (1.0 mmol) in ethanol was added to a hot solution
of complex 1 (2.0 mmol) in chloroform. The resulting solution was cooled and then
added to petroleum ether (boiling range: 40–60°C). the yellow precipitate of the het-
eroleptic complex separated out, which was filtered and dried (Scheme 1). Single crystals
suitable for X-ray structural analysis were obtained by the recrystallization from the
chloroform–acetonitrile solvent mixture. Yield: 77%; m.p. 176–178°C. Anal. Calc for
C H N O S Zn (1612.24): C, 57.94; H, 4.99; N, 5.20; Found: C, 57.95; H,4.96; N,
7
8
80
6
8 8
2
−
1
5
.18; IR (KBr, cm ): 1511 (ν
), 1033 (ν
). UV–VIS (CH Cl , nm): λ = 238, 276.
C−N
C−S
2
2
1
H NMR (400.00 MHz, CDCl , ppm): 3.83 (s, 3H, 4CH O−C H −CH −N); 5.02 (s,
3
3
6
4
2
2
2
H, 4OCH −C H −CH −N); 6.91-7.33 (aromatic protons of dithiocarbamate); 7.69 (d,
3
6
4
2
ꢀ
ꢀ
13 1
H, J = 4.8 Hz, H-3 (4,4 -bipy)); 9.03 (b, 2H, H-2 (4,4 -bipy)). C { H} NMR (100 MHz,
CDCl , ppm): 54.9 (4CH O−C H −CH −N); 55.4 (4CH O−C H −CH −N); 114.0,
3
3
6
4
2
3
6
4
2
ꢀ
1
14.3, 127.1, and 130.0 (other aromatic carbons); 122.1 (C-3 (4,4 -bipy)); 146.5 (C-4
ꢀ
ꢀ
(
4,4 -bipy)); 150.6 (C-2 (4,4 -bipy)); 159.5, (4CH O−Ar); 206 (NCS ).
3
2
4
.5.4. Preparation of complex 4
ꢀ
A hot solution of 2,2 -bipyridine (2.0 mmol) in ethanol was added to a hot solution
of complex 1 (1.0 mmol) in chloroform. The resulting solution was cooled and then
added to petroleum ether (boiling range: 40–60°C). The yellow precipitate separated
out, which was filtered and dried (Scheme 1). Yield: 71%; m.p. 134–136°C. Anal. Calc
for C H N O S Zn (884.15): C, 59.61; H, 5.00; N, 6.32; Found: C, 59.38; H, 4.97;
4
4
44
4
4 4
−
1
N,6.32; IR (KBr, cm ): 1512 (ν
81. H NMR (400.00 MHz, CDCl , ppm): 3.79 (s, 3H, 4CH O−C H −CH −N);
), 1031 (ν
). UV–VIS (CH Cl , nm): λ = 238,
C−N
C−S
2
2
1
2
3
3
6
4
2

JOURNAL OF SULFUR CHEMISTRY
11
5
.04 (s, 2H, 4OCH −C H −CH −N); 6.85–7.30 (aromatic protons of dithiocarba-
3
6
4
2
ꢀ
ꢀ
mate); 7.41 (t, 2H, J = 6.4 Hz, H-4 (2,2 -bipy)); 7.90 (t, 2H, J = 7.6 Hz, H-5 (2,2 -
ꢀ
ꢀ
bipy)); 8.32(d, 2H, J = 7.2 Hz, H-6 (2,2 -bipy)); 8.97 (d, 2H, J = 10.8 Hz, H-3 (2,2 -
1
3
1
bipy)). C { H} NMR (100 MHz, CDCl , ppm): 55.0 (4CH O−C H −CH −N); 55.3
3
3
6
4
2
(
4CH O−C H −CH −N); 114.1, 114.4, 127.8, 128.9, 129.4 and 129.6.0 (other aromatic
3
6
4
2
ꢀ
ꢀ
ꢀ
carbons); 121.0 (C-6 (2,2 -bipy)); 124.4 (C-4 (2,2 -bipy)); 137.9, (C-5)); 149.2 (C-3 (2,2 -
ꢀ
bipy)); 153.8 (C-1 (2,2 -bipy)); 159.2, (4CH O−Ar); 207.8 (NCS ).
3
2
4.5.5. Preparation of zinc sulfide 1
0
.5 g of complex 1 was dissolved in 30 ml of ethyleneglycol in a flask and then heated to
reflux for 15 min. The precipitate obtained was filtered off and washed with methanol.
Disclosure statement
No potential conflict of interest was reported by the authors.
References
[
[
[
1] Nieuwenhuizen PJ, Ehlers AW, Haasnoot JG, et al. The mechanism of zinc(II)-dithiocarba-
mate-accelerated vulcanization uncovered; theoretical and experimental evidence. J Am Chem
Soc. 1999;121:163–168.
2] Bharati P, Bharti A, Nath P, et al. Synthesis, spectral and structural characterization of
cobalt(III) dithiocarbamato complexes: catalytic application for the solvent free enamination
reaction. Polyhedron. 2015;102:375–385.
3] Thomas SR, Salahifar H, Mashima R, et al. Antioxidants inhibit indoleamine 2,3-dioxygenase
in IFN-γ -activated human macrophages: posttranslational regulation by pyrrolidine dithio-
carbamate. J Immunol. 2001;166:6332–6340.
[
4] Adams H, Bailey NA, Bruce DW, et al. Metallo-mesogens and liquid crystals with a heart of
gold. Polyhedron. 1988;7:1861–1867.
[
5] Sreehari N, Varghese B, Manoharan PT. Crystal and molecular structure of dimeric Bis[N,N-
di-n-propyldithiocarbamato]zinc(II) and the study of exchange-coupled copper(II)-copper(II)
pairs in its lattice. Inorg Chem. 1990;29:4011–4015.
[
6] Rolandi A, De Marinis E, De Caterina M. Dithiocarbamate pesticides: activity of Propineb in
the micronucleus test in mice. Mutat Res. 1984;135:193–197.
[
7] Guven K, Power RS, Avramides S, et al. The toxicity of dithiocarbamate fungicides to soil nema-
todes, assessed using a stress-inducible transgenic strain of Caenorhabditis elegans. J Biochem
Mol Toxicol. 1999;13:324–333.
[
8] Tiekink ER. Molecular architecture and supramolecular association in the zinc-triad 1,1-
dithiolates. steric control as a design element in crystal engineering? CrystEngComm.
2
003;5:101–113.
[
9] Benson RE, Ellis CA, Lewis CE, et al. 3D-, 2D- and 1D-supramolecular structures
ꢀ
of {Zn[S2CN(CH2CH2OH)R]2}2 and their {Zn[S2CN(CH2CH2OH)R]2}2(4,4 -bipyridine)
adducts for R = CH2CH2OH, Me or Et: polymorphism and pseudo-polymorphism. Crys-
tEngComm. 2007;9:930–940.
[
10] Singh V, Kumar V, Gupta AN, et al. Effect of pyridyl substituents leading to the formation of
green luminescent mercury(II) coordination polymers, zinc(II) dimers and a monomer. New
J Chem. 2014;38:3737–3748.
[
11] Crooke ST, Mirabelli CK. Molecular mechanisms of action of auranofin and other gold
complexes as related to their biologic activities. Am J Med. 1983;75:109–113.
12] Guerrini L, Garcia-Ramos JV, Domingo C, et al. Sensing polycyclic aromatic hydrocarbons
with dithiocarbamate-functionalized Ag nanoparticles by surface-enhanced Raman scattering.
Anal Chem. 2009;81:953–960.
[

12
P. SELVAGANAPATHI ET AL.
[
13] Dutta B, Bag P, Flörke U, et al. Dinuclear zinc(II) complexes of tetraiminodiphenol macrocycles
and their interactions with carboxylate anions and amino acids. photoluminescence, equilibria,
and structure. Inorg Chem. 2005;44:147–157.
[
[
[
14] Soref RA. Silicon-based group IV heterostructures for optoelectronic applications. J Vac Sci
Technol A. 1996;14:913–918.
15] Zhu Y-C, Bondo Y, Xue DF, et al. Oriented assemblies of ZnS one-dimensional nanostructures.
Adv Mater. 2004;16:831–834.
16] Nyamen LD, Nejo AA, Pullabhotla VSR, et al. The syntheses and structures of Zn(II) hete-
rocyclic piperidine and tetrahydroquinoline dithiocarbamates and their use as single source
precursors for ZnS nanoparticles. Polyhedron. 2014;67:129–135.
[17] Sun J-Q, Shen X-P, Chen K-M, et al. Low-temperature synthesis of hexagonal ZnS
nanoparticles by a facile microwave-assisted single-source method. Solid State Commun.
2
008;147:501–504.
[18] Srinivasan N, Thirumaran S. Synthesis of nanocrystalline ZnS from(1,10-phenanthroline)bis
ꢀ
(
1,2,3,4- tetrahydroquinolinecarbodithioato-S,S )zinc(II), synthesis and reactivity in inor-
ganic, metal-organic, and nano-metal chemistry. Spectrochim Acta Mol Biomol Spectrosc.
013;43:1256–1263.
2
[
[
[
[
[
[
19] Ubale AU, Kulkarni DK. Preparation and study of thickness dependent electrical characteristics
of zinc sulfide thin films. Bull Mater Sci. 2005;28:43–47.
20] Pickett NL, O’Brien P. Syntheses of semiconductor nanoparticles using single-molecular
precursors. Chem Rec. 2001;1:467–479.
21] Anand KV, Chinnu MK, Kumar RM, et al. Thermal stability and optical properties of HMTA
capped zinc sulfide nanoparticles. J Alloys Compd. 2010;496:665–668.
22] Ma Y, Qi L, Ma J, et al. Facile synthesis of hollow ZnS nanospheres in block copolymer solutions.
Langmuir. 2003;19:4040–4042.
23] Khiew PS, Radiman S, Huang NM, et al. Preparation and characterization of ZnS nanoparticles
synthesized from chitosan laurate micellar solution. Mater Lett. 2005;59:989–993.
24] Manohar A, Ramalingam K, Bocelli G, et al. Synthesis, spectral and cyclic voltam-
ꢀ
ꢀ
metric studies on (4,4 -bipyridyl)bis(di(2-hydroxyethyl)dithiocarbamato)zinc(II) and (4,4 -
bipyridyl)bis(bis(N-methyl, N-ethanoldithiocarbamato)zinc(II) and their X-ray crystal struc-
tures. Inorg Chim Acta. 2001;314:177–183.
[
[
[
25] Addison AW, Nageswara Rao T, Reedijk J, et al. Synthesis, structure, and spectroscopic
properties of copper(II) compounds containing nitrogen-sulphur donor ligands; the crys-
ꢀ
tal and molecular structure of aqua[1,7-bis(N-methylbenzimidazol-2 -yl)-2,6-dithiaheptane]
copper(II) perchlorate. J Chem Soc Dalton Trans. 1984;1349–1356.
26] Marimuthu G, Ramalingam K, Rizzoli C. Synthesis, spectral, thermal and BVS inves-
tigations on ZnS4NˆN/N coordination environment: single crystal X-ray structures of
bis(dibenzyldithiocarbamato)(NˆN)zinc(II) complexes (NˆN = 1,10-phenanthroline, tetram-
ꢀ
ethylethylenediamine and 4,4 -bipyridine). Polyhedron. 2010;29:1555–1560.
27] Urgut OS, Ozturk II, Banti CN, et al. New antimony(III) halide complexes with dithiocarba-
mate ligands derived from thiuram degradation: the effect of the molecule’s close contacts on
in vitro cytotoxic activity. Mater Sci Eng C. 2016;58:396–408.
[
28] Pearson RG. Electronic spectra and chemical reactivity. J Am Chem Soc. 1988;110:2092–2097.
29] Sathiyaraj E, Tamilvanan S, Thirumaran S, et al. Effect of functionalization of N-bound
organic moiety in zinc(II) dithiocarbamate complexes on structure, biological properties and
morphology of zinc sulfide nanoparticles. Polyhedron. 2017;128:133–144.
[
[30] Pearson RG. Absolute electronegativity and hardness: application to inorganic chemistry. Inorg
Chem. 1988;27:734–740.
[
[
31] Kittel C, editor. Introduction to solid state physics. Chapter 8. New York: Wiley; 1986.
32] Cimitan S, Albonetti S, Forni L, et al. Solvothermal synthesis and properties control of doped
ZnO nanoparticles. J Colloid Interface Sci. 2009;329:73–80.
[
33] Sheldrick GM. A short history of SHELX. Acta Crystallogr Sect A Found Crystallogr.
2
008;64:112–122.

JOURNAL OF SULFUR CHEMISTRY
13
[
[
[
34] Frisch MJ, Trucks GW, Schlegel HB, et al. Gaussian03, Revision D. 01. Wallingford (CT):
Gaussian Inc.; 2013.
35] Wolff SK, Grimwood DJ, McKinnon JJ, et al. Crystal explorer ver. 3.1. Perth: University of
Western Australia; 2013.
36] Rani PJ, Thirumaran S. Synthesis, characterization, cytotoxicity and antimicrobial studies
on bis(N-furfuryl-N-(2-phenylethyl)dithiocarbamato-S,S’) zinc(II) and its nitrogen donor
adducts. Eur J Med Chem. 2013;62:139–147.