Synthesis, spectral, thermal and BVS investigations on ZnS4N^N/N coordination environment: Single crystal X-ray structures of bis(dibenzyldithiocarbamato)(N^N)Zinc(II) complexes (N^N = 1,10-phenanthroline, tetramethylethylenediamine and 4,4′-bipyridine)

Article abstract of DOI:10.1016/j.poly.2010.02.001

The current paper describes the synthesis and spectral investigations on the adducts of [Zn(dbzdtc)₂] (1) with 1,10-phen (2), tmed (3), 2,2′-bipy (4) and 4,4′-bipy (5) (where, dbzdtc = dibenzyldithiocarbamate anion, 1,10-phen = 1,10-phenanthroline, tmed = tetramethylethylenediamine, 2,2′-bipy = 2,2′-bipyridine, 4,4′-bipy = 4,4′-bipyridne) and single crystal X-ray structures of [Zn(dbzdtc)₂(1,10-phen)] (2) and [Zn(dbzdtc)₂(tmed)] (3) and [Zn(dbzdtc)₂(4,4′-bipy)] (5). ¹H and ¹³C NMR spectra of 1,10-phen, tmed, 2,2′-bipy and 4,4′-bipy adducts were recorded. ¹H NMR spectra of the complexes show the drift of electrons from the nitrogen of the substituents forcing a high electron density towards sulfur via the thioureide π-system. In the ¹³C NMR spectra, the most important thioureide (N¹³CS₂) carbon signals are observed in the region: 206-210 ppm. Fluorescence spectra of complexes (2) and (4) show intense fluorescence due to the presence of rigid conjugate systems such as 1,10-phenanthroline and 2,2′-bipyridine. The observed fluorescence maxima for complexes with an MS₄N₂ chromophore in the visible region are assigned to the metal-to-ligand charge transfer (MLCT) processes. Single crystal X-ray structural analysis of (2) and (3) showed that the zinc atom is in a distorted octahedral environment. Bond Valence Sum was found to be equivalent to 1.865 for (2), 1.681 for (3) supporting the correctness of the determined structure. BVS of (3) deviates from the formal oxidation number of zinc due to the non-aromatic, sterically hindering tetramethyl bonding end of tmed. Thermal studies on the compounds show the formation of Zn(NCS)₂ as an intermediate during the decay.

Full text of DOI:10.1016/j.poly.2010.02.001

Polyhedron 29 (2010) 1555–1560
Contents lists available at ScienceDirect
Polyhedron
journal homepage: www.elsevier.com/locate/poly
Synthesis, spectral, thermal and BVS investigations on ZnS4N^N/N
coordination environment: Single crystal X-ray structures
of bis(dibenzyldithiocarbamato)(N^N)Zinc(II) complexes
(N^N = 1,10-phenanthroline, tetramethylethylenediamine and 4,40-bipyridine)
b
G. Marimuthu a, K. Ramalingam a, , C. Rizzoli
*
a Department of Chemistry, Annamalai University, Annamalainagar 608 002, India
b Department of General and Inorganic Chemistry, University of Parma, Parma 43100, Italy
a r t i c l e i n f o
a b s t r a c t
Article history:
The current paper describes the synthesis and spectral investigations on the adducts of [Zn(dbzdtc)2] (1)
with 1,10-phen (2), tmed (3), 2,20-bipy (4) and 4,40-bipy (5) (where, dbzdtc = dibenzyldithiocarbamate
anion, 1,10-phen = 1,10-phenanthroline, tmed = tetramethylethylenediamine, 2,20-bipy = 2,20-bipyridine,
4,40-bipy = 4,40-bipyridne) and single crystal X-ray structures of [Zn(dbzdtc)2(1,10-phen)] (2) and
[Zn(dbzdtc)2(tmed)] (3) and [Zn(dbzdtc)2(4,40-bipy)] (5). 1H and 13C NMR spectra of 1,10-phen, tmed,
2,20-bipy and 4,40-bipy adducts were recorded. 1H NMR spectra of the complexes show the drift of elec-
trons from the nitrogen of the substituents forcing a high electron density towards sulfur via the thioure-
Received 30 November 2009
Accepted 1 February 2010
Available online 4 February 2010
Keywords:
Dithiocarbamate
Thioureide
ide p
-system. In the 13C NMR spectra, the most important thioureide (N13CS2) carbon signals are observed
NMR
in the region: 206–210 ppm. Fluorescence spectra of complexes (2) and (4) show intense fluorescence
due to the presence of rigid conjugate systems such as 1,10-phenanthroline and 2,20-bipyridine. The
observed fluorescence maxima for complexes with an MS4N2 chromophore in the visible region are
assigned to the metal-to-ligand charge transfer (MLCT) processes. Single crystal X-ray structural analysis
of (2) and (3) showed that the zinc atom is in a distorted octahedral environment. Bond Valence Sum was
found to be equivalent to 1.865 for (2), 1.681 for (3) supporting the correctness of the determined struc-
ture. BVS of (3) deviates from the formal oxidation number of zinc due to the non-aromatic, sterically hin-
dering tetramethyl bonding end of tmed. Thermal studies on the compounds show the formation of
Zn(NCS)2 as an intermediate during the decay.
Fluorescence
Single crystal X-ray structure
Ó 2010 Elsevier Ltd. All rights reserved.
1. Introduction
adducts of [Zn(dbzdtc)2] (1) with 1,10-phen (2), tmed (3), 2,20-bipy
(4) and 4,40-bipy (5) (where, dbzdtc = dibenzyldithiocarbamate,
Dithiocarbamates of zinc and cadmium have continued to
attract attention in recent years on account of their industrial
applications [1,2] and biological profiles [3,4]. A recent work has
established that cadmium dithiocarbamates may be useful precur-
sors to form CdS nanowires [5] with potential applications [6]. Var-
ious main group metal-dithiolates have been investigated as
precursors in metal organic chemical vapor deposition (MOCVD)
[7–9]. The affinity of Zn and Cd towards sulfur containing ligands
leads to many structurally novel compounds, which is a well-doc-
umented phenomenon [10–12]. In our efforts to correlate structure
and fluorescent properties of Group XII metal dithiocarbamates
and their adducts, synthesis and spectral characterization of the
1,10-phen = 1,10-phenanthroline, tmed = tetramethylethylenedi-
amine, 2,20-bipy = 2,20-bipyridine, 4,40-bipy = 4,40-bipyridne) along
with the single crystal X-ray structures of [Zn(dbzdtc)2(1,10-
phen)] (2), [Zn(dbzdtc)2(tmed)] (3) and [Zn(dbzdtc)2 (4,40-bipy)]
(5). are reported in this paper.
2. Experimental
All the regents and solvents employed were commercially avail-
able analytical grade materials and were used as supplied without
further purification. IR spectra were recorded on an ABB Bomen MB
104 spectrometer (range 4000–500 cmꢀ1) as KBr pellets. The UV–
Vis spectra were recorded in benzene on a HITACHI U-2001 spec-
trophotometer. Fluorescence spectra of the free ligands, parent
complexes and adducts were recorded in benzene. To prevent
any non-linearity of the fluorescent intensity, 400 nm was chosen
* Corresponding author. Tel.: +91 413 2202834; fax: +91 414 422265.
E-mail address: krauchem@yahoo.com (K. Ramalingam).
0277-5387/$ - see front matter Ó 2010 Elsevier Ltd. All rights reserved.
doi:10.1016/j.poly.2010.02.001

1556
G. Marimuthu et al. / Polyhedron 29 (2010) 1555–1560
as the excitation wavelength. Thermal analysis was carried out on
a Perkin–Elmer-Pyris-Diamond instrument.
2.2.4. Preparation of [Zn(dbzdtc)2(2,2-bipy)] (4)
A mixture of Zn(dbzdtc)2 (0.25 mmol, 0.152 g) and 2,20-bipyri-
dine (0.25 mmol, 0.039 g) in acetonitrile–methanol (2:1 v/v;
20 ml) was refluxed for about 2 h followed by concentration to
10 ml. After two days a yellow solid separated out from the solu-
tion. The solid was filtered and was dried over anhydrous calcium
chloride. (Yield: 70%; dec. 233–235 °C.). Anal. Calc. for
C40H36N4S4Zn: C, 62.69; H, 4.73; N, 7.31. Found: C, 62.40; H,
4.44; N, 7.01%.
2.1. X-ray crystallography
Intensity data were collected at ambient temperature (295 K)
using graphite monochromated Mo K
on a Bruker CCD diffractometer for (2) and (5), respectively. Data
for (3) were collected on a Philips PW1100 diffractometer. Data
for (2) and (5) were corrected for absorption using the SADABS pro-
a radiation (k = 0.71073 Å)
2.2.5. Preparation of [Zn(dbzdtc)2(4,4-bipy)] (5)
gram [13], while those for (3) were corrected using the
W-scan
A mixture of Zn(dbzdtc)2 (0.25 mmol, 0.152 g) and 4,40-bipyri-
dine (0.25 mmol, 0.039 g) in acetonitrile–methanol (2:1 v/v;
20 ml) was refluxed for about 2 h followed by concentration to
10 ml. After two days a pale yellow solid separated out from the
solution. The solid was filtered and was dried over anhydrous cal-
cium chloride. (Yield: 85%; dec. 221–223 °C). Anal. Calc. for
C70H64N6S8Zn2: C, 61.07; H, 4.69; N, 6.10. Found: C, 60.77; H,
4.41; N, 5.92%.
technique [14]. All non-hydrogen atoms were refined anisotropi-
cally and all the hydrogen atoms were fixed geometrically. The OR-
TEP diagrams were drawn with the ORTEP-3 program [15].
2.2. Preparation of the complexes
2.2.1. Preparation of [Zn(dbzdtc)2] (1)
Dibenzylamine (2 mmol) and carbon disulfide (2 mmol) in eth-
anol (10 ml) were mixed under ice-cold condition (5 °C) to form a
yellow solution of dithiocarbamic acid. An aqueous solution of zinc
nitrate hexahydrate (1 mmol) was then added with continuous
stirring. A pale yellow precipitate was obtained, which was washed
with ethanol and was then dried in air. (Yield: 70%; dec. 170–
172 °C). Anal. Calc. for C30H28N2S4Zn: C, 59.05; H, 4.62; N, 4.59.
Found: C, 59.01; H, 4.30; N, 4.26%.
3. Results and discussion
3.1. Infrared spectral studies
Infrared spectral data of the complexes are shown in Table 1.
For the present set of compounds 1-5, the mC–N (thioureide) band
appears in the region: 1470–1490 cmꢀ1. The mC–S bands are ob-
served around 1100 cmꢀ1 (1–5) without any splitting, supporting
the bidentate coordination mode of the dithiocarbamate to the me-
tal center, and the mC–H bands are observed around 2900 and
2800 cmꢀ1. The characteristic bands due to 1,10-phenanthroline
appear around 1650, 1600 cmꢀ1 in the adducts. In the case of
2,20-bipyridine adduct a characteristic band appeared at 15ꢀ918
2.2.2. Preparation of [Zn(dbzdtc)2(1,10-phen)] (2)
A mixture of Zn(dbzdtc)2 (0.25 mmol, 0.152 g) and 1,10-phen
(0.25 mmol, 0.049 g) in acetonitrile-methanol (2:1 v/v; 20 ml)
was refluxed for about 2 h followed by concentration to 10 ml.
After two days, a pure yellow solid separated out from the solution.
The solid was filtered and was dried over anhydrous calcium chlo-
ride. Single crystals suitable for X-ray diffraction analysis were ob-
tained by slow evaporation of an acetonitrile, benzene and
cmꢀ1. Similarly, for 4,40-bipyridine, a band appeared at 1608 cm
.
3.2. Thermogravimetric studies
chloroform (1:1:1 v/v/v) solution. (Yield: 65%; dec. 254–256 °C).
Anal. Calc. for C42H36N4S4Zn: C, 63.82; H, 4.59; N, 7.09. Found: C,
Zn(dbzdtc)2 (1) starts to decompose above 60 °C, indicating the
loss of water molecules of crystallization (experimentally observed
loss: 2.8%; theoretically expected: 2.9%). Immediately after the loss
of water molecules, a single decomposition step sets in and pro-
ceeds up to 360 °C corresponding to the stabilization of Zn(NCS)2
(experimentally observed residue: 29.2%; theoretically expected
28.9%). At around 370 °C, another thermal decay is observed
corresponding to the stabilization of ZnS (experimentally observed
residue: 15.4; theoretically expected 15.5). All the three decompo-
sitions mentioned are endothermic in nature.
From the thermograms of the adducts, it is found that all
the complexes show almost similar thermal behavior.
[Zn(dbzdtc)2(1,10-phen)](2) shows the loss of 1,10-phenanthroline
(385 °C; 21.8%) followed by the thermal decay of dithiocarbamate
63.52; H, 4.29; N, 6.89%.
2.2.3. Preparation of [Zn(dbzdtc)2(tmed)] (3)
A mixture of Zn(dbzdtc)2 (0.25 mmol, 0.152 g) and tetramethyl-
ethylenediamine (0.25 mmol, 0.037 ml) in acetonitrile–methanol
(2:1 v/v; 20 ml) was refluxed for about 2 h followed by concentra-
tion to 10 ml. After two days pale yellow solid separated out from
the solution. The solid was filtered and was dried over anhydrous
calcium chloride. Single crystals suitable for X-ray diffraction were
obtained by slow evaporation of an acetonitrile, benzene and chlo-
roform (1:1:1 v/v/v) solution. (Yield: 65%; dec. 176-178°C). Anal.
Calc. for C36H44N4S4Zn: C, 59.52; H, 6.11; N, 7.71. Found: C,
59.22; H, 5.85; N, 7.40%.
Table 1
Infrared spectral data (values in cmꢀ1) for the complexes.
Complex
mC–N thioureide
mC–S
mC–H
1,10-phen, 2,20-bipy/4,40-bipy ring frequencies
Phenyl ring mC–H
[Zn(dbzdtc)2] (1)
1482
1077
2920
2852
2917
2863
2909
2852
2918
2854
2922
2853
635–754
[Zn(dbzdtc)2(1,10-phen)] (2)
[Zn(dbzdtc)2(tmed)] (3)
1493
1493
1492
1470
1093
1077
1075
1074
1656
1600
696–729
635–734
697–762
635–737
[Zn(dbzdtc)2(2,20-bipy)] (4)
[Zn(dbzdtc)2(4,40-bipy)] (5)
1598
1608

G. Marimuthu et al. / Polyhedron 29 (2010) 1555–1560
1557
up to 500 °C leading to formation of Zn(NCS)2. Further increase in
temperature indicates ZnS as the final residue. [Zn(dbzdtc)2(tmed)]
(3) shows the initial decomposition of the tmed (300 °C; 14.9%) fol-
lowed by dithiocarbamate. The final residue stabilized around
610 °C conformed to ZnS. Thermal decay of [Zn(dbzdtc)2(2,20-
bipy)] (4) shows initial loss of 2,20-bipy (20.0%; 350 °C). Subse-
quent loss led to the formation of Zn(NCS)2 (24.3%; 500 °C) and
ZnS as final residue. [Zn(dbzdtc)2(4,40-bipy)](5) showed a single
stage thermal decomposition starting at 310 °C. Loss of 4,40-bipy
and dithiocarbamate moieties concertedly decomposed in a single
step. The final residue formed at 610 °C was found to be ZnS. Com-
parison of the thermal stabilities of the parent and its adducts
clearly shows a higher thermal stability of the adducts during
decomposition. Formation of Zn(NCS)2 takes place at a relatively
lower temperature for the parent compared to its adducts. How-
ever, the formation of ZnS for all the adducts is complete around
600 °C.
protons undergo weak deshielding and appear in the range of
7.10–7.45 ppm in all the complexes. Apart from the aromatic sig-
nals due to the dibenzyl moiety, the ring protons of 1,10-phenan-
throline in (2) appear above 7.45 ppm. Complexes (4) and (5) also
show signals above 7.46 ppm due to 2,20-bipyridine and 4,40-bipyr-
idine respectively. In all the adducts, (2), (4) and (5) which involve
aromatic nitrogenous bases, the signal corresponding to the proton
adjacent to the coordinated nitrogen is clearly shifted to higher
field compared to the free base.
Methyl protons of tmed appear at 2.24 ppm and those of meth-
ylene group appear at 2.38 ppm in uncomplexed tmed. The two
signals at 2.63 ppm and 2.59 ppm in complex (3) are ascribed to
methylene and methyl protons of tmed on complexation. The N-
CH2 and N-CH3 proton signals are clearly deshielded on complexa-
tion. All the adducts show slight downfield shift compared to free
nitrogenous ligands due to the reduced electron density of 1,10-
phenanthroline, tmed, 2,20-bipyridine and 4,40-bipyridine groups.
3.3. NMR spectral studies
3.3.2. 13C NMR
The signals observed around 206.2–210.3 ppm for the com-
plexes (1), (2), (3), (4) and (5) are assigned to the thiouride carbon
NMR spectral data of all the synthesized compounds are given
in Table 2 along with the splitting patterns.
d(N13CS2). A down field shift of the
a-carbon signals (to the thio-
ureide
p-system) in the case of complexes (2), and (3) is an indica-
3.3.1. 1H NMR
tion of the important consequence of the complexation process,
viz., a significant thioureide contribution to the stability of the
complexes and a resultant reduction in the electron density.
For the compounds (2), (3), (4) and (5) phenyl ring carbons res-
onate in the region of 127.4–141.4 ppm. The methylene and
methyl carbons of tmed in (3) show signals at 56.6 and 46.3 ppm
Signals observed around 5.17 ppm for complexes (1), (2), (3), (4)
and (5) are due to benzylic-CH2 protons of the dithiocarbamate.
The observed deshielding of the –CH2 protons in all the compounds
[16] is attributed to the shift of electron density towards the nitro-
gen of the NR2 groups, forcing high electron density on the sulfur
(or the metal) through the thioureide
p-system. The phenyl ring
respectively. The assignment of the deshielded signal to the a-car-
Table 2
1H and 13C NMR spectral data of the complexes (chemical shifts in ppm).
Compound
NMR
Phenyl ring protons/carbons
Benzylic–CH2
N–CH3
N
13C S2 (thioureide)
1,10-Phen ring/2,20-bipy 4,40-bipy ring/tmed
ꢀCH2ꢀ and ꢀCH3 protons and carbons
1
1H
7.28–7.45
134.5-ipso carbon
128.9
5.09
55.8
13C
206.2
128.2
128.1
7.10–7.32
2
1H
5.17
55.9
9.70
8.27–8.29
7.69–7.72
7.78
149.0
137.7
127.4
126.5
124.5
2.63 –CH2ꢀ
2.59 ꢀCH3
56.6 –CH2ꢀ
46.3 –CH3
13C
141.4
136.3-ipso carbon
128.8
210.3
209.8
3
4
1H
7.23–7.35
5.17
55.8
13C
136.0-ipso carbon
128.6
127.8
127.4
7.25–7.35
46.3
1H
5.14
55.8
9.26
8.20–8.22
7.93–7.96
7.46–7.49
150.9
149.1
135.7
125.1
120.8
9.14-9.16
7.75-7.76
150.6
13C
138.6-ipso carbon
128.7
127.9
208.9
207.3
127.6
5
1H
7.287.
5.15
55.9
35–7.44
135.1-ipso carbon
129.0
13C
146.7
128.9
122.3
128.1

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G. Marimuthu et al. / Polyhedron 29 (2010) 1555–1560
bon is accomplished by considering the pronounced electron with-
drawing effect of the NCS2 -system and the closer proximity of
the -carbons to the metal center. The observed small differences
masking of the lone pair of electrons of nitrogen through a
photo-induced electron transfer (PET) [19]. Complex (2) shows
fluorescence bands with comparatively high intensity compared
to the other octahedral complexes due to the presence of rigid aro-
matic 1,10-phenanthroline in the metal chelate.
p
a
in chemical shifts for the 1,10-phenanthroline, tmed,2,20-bipyri-
dine and 4,40-bipyridine fragments in the adducts (2), (3), (4) and
(5) compared to the free nitrogenous ligands signals can be attrib-
uted to charge delocalization, which prevents the movement of
electron density from the adjacent carbons. Generally, the extent
of deshielding for the thioureide N13CS2 signal in main group metal
dithiocarbamates is greater in magnitude than those of normal va-
lence state transition metal dithiocarbamates, which is in line with
the observed thioureide carbon chemical shifts of the synthesized
compounds [17]. In the case of parent bisdithiocarbamate (1) the
thioureide carbon appears at 206.2 ppm whereas all the adducts
show the corresponding signals at higher values. The highest
chemical shift for the thioureide carbon is observed for the1,10-
phenanthroline adduct (2), viz.., 210.3 ppm.. The increasing trend
in the chemical shifts of the thioureide carbon of adducts is a clear
indication of the the reduced contribution of polar thioureide bond
in the adducts compared to the parent dithiocarbamate.
3.5. Structural analysis
Details of crystal data, data collection and refinement parame-
ters for (2), (3) and (5) are summarized in Table 3. Selected bond
distances and bond angles are given in Table 4, and a comparison
of structural parameters for compounds (1), (2), (3) and (5) is given
in Table 5. Crystal structure of (4) and (5) have been reported ear-
lier and the structure of (5) showed the phenyl rings with disorder
[20,21]. The crystal structure of (5) has been re-determined for
comparison with better reliability index and fortunately there
was no disorder.
[Zn(dbzdtc)2(1,10-phen)] (2), [Zn(dbzdtc)2(tmed)] (3) and
[Zn(dbzdtc)2(4,40-bipy)] (5) are monomeric and discrete. ORTEP
diagrams of (2), (3) and (5) are shown in Figs. 1–3 together with
the atom-numbering scheme. Four formula units are present in
the unit cell. In both complexes, the zinc metal center is six-coor-
dinated by four sulfur atoms from the dithiocarbamte ligands and
two nitrogen atoms from the chelating 1,10-phenanthroline and
tmed.
3.4. Fluorescence spectral studies
M(dtc)2 (where M = Zn and Cd and dtc = general notation for the
dithiocarbamate anion) complexes show less intense (or) no fluo-
rescence in the visible region. It may be attributed to the absence
of effective fluorophores in the parent complexes or a less effective
charge transfer transition [18]. On excitation of complexes (2), (3),
(4) and (5) which have MS4N2/MS4N chromophores, fluorescence
maxima are observed in the region of 400–420 nm. This is ascribed
to a possible metal ligand charge transfer (MLCT) or the brief
The complex (2) has crystallographically imposed twofold sym-
metry, with Zn lying on a rotation axis. The short thioureide C–N
distance of 1.341(2) Å indicates that the
p electron density is delo-
calized over the S2CN moiety and that this bond has some double
bond character. Because of the small bite angle [S–Zn–
S = 70.840(16)°] of the dithiocarbamte and the steric influence of
Table 3
Crystal data, data collection and refinement parameters for (2), (3) and (5).
Complex
(2)
(3)
(5)
Empirical formula
Formula weight
C42H36N4S4Zn
790.4
C36H44N4S4Zn
726.4
C70H64N6S8Zn2
1376.49
Crystal dimensions (mm) 0.18 ꢁ 0.18 ꢁ 0.14
0.25 ꢁ 0.17 ꢁ 0.14
monoclinic
colorless
block
0.32 ꢁ 0.20 ꢁ 0.12
Crystal system
Color
monoclinic
colorless
block
triclinic
pale yellow
block
Habit
ꢀ
Space group
C2/c
P21/n
P1
a (Å)
b (Å)
c (Å)
25.1103(17)
10.5234(17)
15.0366(10)
90
108.9948(11)
90
3757.0(4)
4
1.397
11.643(2)
11.872(2)
26.509(5)
90
92.646(7)
90
3660.3(11)
4
1.318
10.775(2)
12.793(2)
13.497(3)
94.290(3)
105.367(4)
107.255(3)
1689.3(6)
1
a
(°)
b (°)
c
(°)
U (Å3)
Z
Dcalc (g cmꢀ3
)
1.353
1.003
l
(cmꢀ1
)
0.913
0.930
F(0 0 0)
1640
1528
714
h (°)
Diffractometer
Scan type
1.72–27.11
Bruker APEXII CCD
3.08–25.25
Philips PW1100
1.59–25.25
Bruker SMART CCD
x scans
x
scans
x
-2h
Index ranges
ꢀ32 6 h 6 32; ꢀ13 6 k 6 13; ꢀ19 6 l 6 19
ꢀ13 6 h 6 13; 0 6 k 6 14; 0 6 l 6 31
ꢀ12 6 h 6 12; ꢀ15 6 k 6 15;
ꢀ16 6 l 6 16
16 340
6098
Reflections collected
Unique reflections
Observed reflections
23 930
4155
3364
6463
6457
4101
4238
F0 > 4r (F0)
Weighting scheme
w = 1/[
r
2(Fo2) + (0.0534P)2 + 0.5556P], where
w = 1/[
r
2(Fo2) + (0.0163P)2], where
w = 1/[r
2(Fo2) + (0.0114P)2], where
P = (Fo2 + 2 Fc2)/3
P = (Fo2 + 2 Fc2)/3
P = (Fo2 + 2 Fc2)/3
Number of parameters
231
406
389
refined
Final R, Rw (observed
data)
0.0330, 0.0897
1.073
0.0370, 0.0537
0.984
0.0243, 0.0445
0.992
Goodness-of-fit (GOF) on
F2

G. Marimuthu et al. / Polyhedron 29 (2010) 1555–1560
1559
Table 4
Selected bond distances (Å) and bond angles (°) for complexes (2), (3) and (5).
(2)
(3)
(5)
Zn1–S1
Zn1–S2
2.5395(6)
2.5259(5)
Zn1–S1
Zn1–S2
Zn1–S3
Zn1–S4
2.6664(9)
2.4543(8)
2.6031(8)
2.4952(8)
Zn1–S1
Zn1–S2
Zn1–S3
Zn1–S4
2.3231(7)
2.6144(7)
2.3364(7)
2.6248(7)
Zn1–N2
2.1646(15)
Zn1–N3
Zn1–N4
2.261(2)
2.243(2)
Zn1–N3
2.0627(14)
S1–C1
S2–C1
1.7092(18)
1.7154(19)
S1–C1
S2–C1
S3–C16
S4–C16
1.711(2)
1.723(3)
1.704(3)
1.725(2)
S1–C1
S2–C1
S3–C16
S4–C16
1.7305(18)
1.7102(18)
1.7315(19)
1.7184(17)
N1–C1
N1–C2
N1–C9
1.341(2)
1.460(2)
1.463(2)
N1–C1
N1–C2
N1–C9
N2–C16
N2–C17
N2–C24
N3–C31
1.349(3)
1.477(3)
1.459(3)
1.350(3)
1.460(3)
1.462(3)
1.480(3)
N1–C1
N1–C2
1.342(2)
1.466(2)
N2–C16
N2–C17
N2–C24
N3–C31
1.336(2)
1.4746(19)
1.482(2)
1.321(2)
N2–C16
N2–C20
1.320(3)
1.349(2)
N3–C33
N3–C34
N4–C32
N4–C35
N4–C36
1.475(3)
1.478(3)
1.477(3)
1.477(3)
1.472(3)
N3–C35
1.324(2)
S1–Zn1–S2
70.840(16)
S1–Zn1–S2
S3–Zn1–S4
70.21(2)
70.69(3)
S1–Zn1–S2
S3–Zn1–S4
73.136(19)
72.866(18)
C1–S1–Zn1
C1–S2–Zn1
85.38(6)
85.69(6)
C1–S1–Zn1
C1–S2–Zn1
C16–S3–Zn1
C16–S4–Zn1
82.41(9)
88.92(8)
82.64(9)
85.62(9)
C1–S1–Zn1
C1–S2–Zn1
N3–Zn1–S1
N3–Zn1–S2
88.72(6)
80.03(6)
115.48(5)
95.54(4)
S1–C1–S2
118.02(11)
S1–C1–S2
S3–C16–S4
118.42(14)
118.72(16)
S1–C1–S2
N3–Zn1–S3
118.11(11)
115.14(4)
C1–N1–C2
C1–N1–C9
C2–N1–C9
122.73(16)
122.60(16)
114.62(16)
C1–N1–C2
C1–N1–C9
C2–N1–C9
C16–N2–C17
C16–N2–C24
C17–N2–C24
124.1(2)
121.2(2)
114.32(18)
121.8(2)
122.5(2)
115.3(2)
C1–N1–C2
N3–Zn1–S4
C2–N1–C9
S1–Zn1–S3
S2–Zn1–S4
S1–Zn1–S4
122.53(15)
93.65(4)
114.99(15)
129.20(2)
170.256(17)
99.92(2)
Table 5
Comparison of bond parameters (Å, °) of related complexes.
Complex
Zn–S
Zn–S
Zn–N
Cdtc–N
S–C–S
[Zn(dbzdtc)2]a (1)
[Zn(dbzdtc)2(1,10-phen)] (2)
[Zn(dbzdtc)2(tmed)] (3)
2.3389(7)
2.5395(6)
2.6664(9)
2.6031(8)
2.3231(7)
2.3364(7)
2.3682(7)
2.5259(5)
2.4543(8)
2.4952(8)
2.6144(7)
2.6248(7)
1.335(3)
1.341(2)
1.349(3)
1.350(3)
1.342(2)
1.336(2)
117.6(13)
2.1646(15)
2.261(2)
2.243(2)
118.02(11)
118.42(14)
118.72(16)
118.11(11)
117.89(11)
[Zn(dbzdtc)2(4,40-bipy)]b (5)
2.0627(14)
a
Ref. [24].
Ref. [20].
b
1,10-phenanthroline, the metal atom is in a highly distorted octa-
hedral coordination environment. The significant asymmetry in
the Zn–S distances [2.5395(6) and 2.5259(5) Å] is due to the steric
effect exerted by 1,10-phenanthroline, as observed in similar ad-
ducts. The C–S distances [mean value 1.7123(19 Å] are on the con-
trary not significantly different. The Zn–N distance is 2.1646(15) Å.
The C–C and C–N bond distances associated with the benzyl groups
are normal.
In complex (3), the values of the thioureide C–N distances
[1.349(3) and 1.350(3) Å] and the bite angle of the dithiocarbamate
[70.21(2) and 70.69(3)°] are comparable with those observed in
(2). The remarkable asymmetry in the Zn–S distances [mean values
2.6347(9) and 2.4747(8) Å] is due to the steric influence of neutral
tmed ligand in the distorted octahedral geometry. The C-S dis-
tances within the same dbzdtc anion as well as the Zn–N bond
lengths (Table 4) are a little, but significantly different. The benzyl
groups show normal bond parameters and the changes in the bond
parameters of tmed are due to chelation with the metal ion. In
complex (5), zinc is in a five coordinate environment with 4,40-
bipyridyl acting as a bridging ligand. The Zn–S distances are asym-
metric due to adduct formation. The most important difference ob-
served in the structural parameter of (5) is that the Zn–N distance
is relatively very short (2.0627 (14) Å) compared to the bidentate
nitrogenous adducts.
Comparison of the bond parameters of the parent bis(dithio-
carbamato)zinc(II) and the adducts (Table 5) clearly shows the sig-
nificant increase in the Zn–S distances due to the addition of a
bulky 1,10-phenanthroline, 2,20-bipyidine [20] tmed or 4,40-bipyr-
idyl ligands to zinc. Comparison of the thioureide C–N bond
lengths clearly shows a significant elongation in the adducts which

1560
G. Marimuthu et al. / Polyhedron 29 (2010) 1555–1560
indicates a reduced electron density flow towards the metal ion
from the dithiocarbamate moiety.
3.6. BVS analysis
Bond valence sum (BVS) analysis can be applied to estimate the
bond lengths; vice versa the sum of the bond lengths should give
information about the valence of the central metal ion. Hence
BVS studies indirectly prove the correctness of the crystal struc-
tures determined. For complex (2), the BVS was calculated to be
1.8653 (OK/B) which is close to the expected formal oxidation state
of 2 [22,23]. It has been already reported that in the case of the par-
ent [Zn(dbzdtc)2], the BVS value is 1.9 and generally the value is
greater than those of the adducts. The decrease in BVS values in
the case of adducts is due to the increase in Zn–S distances (which
are longer than those observed in the parent bisdithiocarbamate.).
For complex (3), the BVS is 1.6811 (OK/B), which is very low. The
observation is supported by the fact that the Zn–S distances in
tmed adduct are longer than those observed in 1,10-phenanthro-
line due to high steric hindrance. In complexes (2) and (3), the
BVS values are approximately close to 2.0 irrespective of coordina-
tion number, confirming the formal valency of zinc in the com-
plexes. The larger deviation of the BVS value of (3) from the
formal oxidation number is due to the non-aromatic, sterically hin-
dering tetramethyl bonding end of tmed as opposed to the aro-
matic, planar rigid phenanthroline.
Fig. 1. ORTEP diagram of [Zn(dbzdtc)2(1,10-phen)] (2) with displacement ellipsoids
drawn at the 50% level. Symmetry code: i = ꢀx, y, 1/2 ꢀ z.
4. Supplementary data
CCDC 724128, 724295 and 760692 contain the supplementary
crystallographic data for (2), (3) and (5). These data can be ob-
tained free of charge via http://www.ccdc.cam.ac.uk/conts/retriev-
ing.html, or from the Cambridge Crystallographic Data Centre, 12
Union Road, Cambridge CB2 1EZ, UK; fax: (+44) 1223-336-033;
or e-mail: deposit@ccdc.cam.ac.uk.
References
[1] J. Nieuwenhuizen, A.W. Ehless, J.G. Haashoot, S.R. Janse, J. Reedijk, J. Baerends,
J. Am. Chem. Soc. 121 (1999) 163.
[2] J.A. McCleverty, S. Gill, J. Chem. Soc., Dalton Trans. (1982) 493.
[3] J.S. Casas, A. Sanchez, J. Bravo, S. Garcia-Fontan, E.E. Castellano, M.M. Jones,
Inorg. Chim. Acta 158 (1989) 119.
[4] M.M. Jones, S.G. Jones, Inorg. Chim. Acta 79 (1983) 288.
[5] P. Yan, Y. Xie, Y. Qien, X. Liu, Chem. Commun. (1999) 1293.
[6] D.W. Tomlin, T.M. Cooper, D.E. Zelmon, Z. Gebeyehu, J.M. Hughes, Acta
Crystallogr., Sect. C55 (1999) 717.
Fig. 2. ORTEP diagram of [Zn(dbzdtc)2(tmed)] (3) with displacement ellipsoids
drawn at the 50% level.
[7] P.Ó. Brien, J.R. Walsh, I.M. Watson, M. Motevalli, L. Hendriksen, J. Chem. Soc.,
Dalton Trans. (1996) 2491.
[8] J. Cheon, J. Am. Chem. Soc. 119 (1997) 163.
[9] M. Bochmann, Chem. Vap. Deposition 2 (1996) 85.
[10] E.R.T. Tiekink, CrystEngCommun. 5 (21) (2003) 101.
[11] R.J. Magee, J.O. Hill, Rev. Anal. Chem. 8 (1985) 5.
[12] S.P. Huang, K.J. Franz, E.H. Arnold, J. Devenyi, R.H. Fish, Polyhedron 15 (1996)
4241.
[13] Bruker, SADABS (Version 2007/4). Bruker AXS Inc., Madison, Wisconsin, USA,
2008.
[14] A.C.T. North, D.C. Phillips, F.S. Mathews, Acta Crystallogr., Sect. A24 (1968) 351.
[15] L.J. Faruggia, ORTEP-3 for Windows, University of Glasgow, Scotland, UK, 1999.
[16] F.A. Cotton, G. Wilkinson, P.L. Gaus, Basic Inorganic Chemistry, 3rd ed., Wiley,
1994.
[17] H.L.M. Van Gaal, J.W. Diesveld, F.W. Pijpers, J.G.M. VanDer Lindon, Inorg. Chem.
18 (1979) 3251.
[18] M. Saravanan, K. Ramalingam, G. Bocelli, A. Cantoni, Appl. Organomet. Chem.
18 (2004) 103.
[19] W. Wang, G. Springnsteen, S. Gao, B. Wang, Chem. Commun. (2000) 1283.
[20] X. Yin, W. Zhang, J. Fan, F.X. Wei, C.S. Lai, E.R.T. Tiekink, Appl. Organomet.
Chem. 17 (11) (2003) 889.
[21] C.S. Lai, E.R.T. Tiekink, Appl. Organomet. Chem. 18 (4) (2004) 197.
[22] N.E. Brese, M.Ó. Keeffe, Acta Crystallogr., Sect. B 47 (1991) 192.
[23] M.Ó. Keeffe, N.E. Brese, J. Am. Chem. Soc. 113 (1991) 3226.
[24] A. Decken, R.A. Gossage, M.Y. Chan, C.S. Lai, E.R. Tiekink, Appl. Organomet.
Chem. 18 (2004) 101.
Fig. 3. ORTEP diagram of [Zn(dbzdtc)2(4,40-bipy)] (5) with displacement ellipsoids
drawn at the 50% level.