Synthesis and characterization of metal complexes of N-alkyl-N-phenyl dithiocarbamates

Article abstract of DOI:10.1016/j.poly.2010.01.011

Ammonium N-ethyl-N-phenyl dithiocarbamate (L¹) and N-butyl-N-phenyl dithiocarbamate (L²), and their group 12 metal complexes formulated as Zn₂L¹₄, CdL¹₂, HgL¹₂

Full text of DOI:10.1016/j.poly.2010.01.011

Polyhedron 29 (2010) 1431–1436
Contents lists available at ScienceDirect
Polyhedron
journal homepage: www.elsevier.com/locate/poly
Synthesis and characterization of metal complexes
of N-alkyl-N-phenyl dithiocarbamates
*
Damian C. Onwudiwe, Peter A. Ajibade
Department of Chemistry, University of Fort Hare, Private Bag X1314, Alice 5700, South Africa
a r t i c l e i n f o
a b s t r a c t
Ammonium N-ethyl-N-phenyl dithiocarbamate (L1) and N-butyl-N-phenyl dithiocarbamate (L2), and
their group 12 metal complexes formulated as Zn2L14, CdL12, HgL12, Zn2L24, CdL22, HgL22 have been syn-
thesized and characterized by elemental analyses, IR, 1H and 13C NMR spectroscopy. The crystal struc-
Article history:
Received 16 July 2009
Accepted 12 January 2010
Available online 20 January 2010
tures of the zinc complexes (Zn2L1 and Zn2L24) are also reported. Single crystal analyses of the two
4
complexes revealed the presence of distorted trigonal bipyramidal and tetrahedral coordination geome-
try about the metal ions. The dithiocarbamate acts as bidentate chelating and bidentate bridging ligands
between the metal ions giving centrosymmetric dimeric molecules. The apparent substitution of the
ethyl substituents in L1 by the butyl groups in L2 results in profound change in structure.
Ó 2010 Elsevier Ltd. All rights reserved.
Keywords:
Crystal structures
Dithiocarbamates
Metal complexes
X-ray diffraction
1. Introduction
[M(S2CNR2)2], where R = alkyl group, are the most common and
many studies and reviews have been done on transition and non-
The dialkyldithiocarbamates anions –S2CNR2 and its derivatives
are used extensively in inorganic and organic chemistry and as ac-
tive agents in pharmacology, medicinal and biochemistry [1,2].
Dithiocarbamates can act as monodentate, bidentate chelating or
bidentate bridging ligands. These binding properties determine
the structural organization of the resulting metal complexes [3].
A wide range of chemistry has been developed around them, and
seemingly small modifications to the ligand can lead to significant
changes in the structure–behavior of the complexes formed with a
particular metal. Metal dithiocarbamates have aroused a lot of
interests due to their structural features [4,5], and can thus be used
as lubricants, antioxidants, accelerators for rubber vulcanization
[6], and biocidal applications [7–10]. Dithiocarbamates derived
from secondary amines are the most studied ones because they
are stable and possess interesting electrochemical and optical
properties [11,12].
The dithiocarbamate chemistry of the group 12 elements is well
developed and as expected, their chemistry is constrained to the +2
oxidation state. The ease and stability of the complexation reaction
is on the fact that group 12 metals act as strong Lewis acids, and
hence readily complex to electron-rich sulfur containing ligands
in the principle of Hard Soft [Lewis] Acid Base, HSAB [13]. These
complexes have been found to be good air-stable precursors for sul-
fides of Cd, Zn, and Hg and in the construction of new supramolec-
ular structural motifs [14,15]. The bis (dithiocarbamate) complexes
transition metals [16,17]. Few reports appear on the corresponding
phenyl derivatives probably due to their instability. In order to
investigate the structural diversity of alkyl-aryldithiocarbamates
complexes, we report the synthesis and characterization of Zn(II),
Cd(II) and Hg(II) complexes of N-ethyl-N-phenyldithiocarbamate
and N-butyl-N-phenyldithiocarbamate.
2. Experimental
All reagents and chemicals were used as obtained. Elemental
analyses were performed on a Fisons elemental analyzer at the
University of Cape Town, South Africa. FTIR spectra were obtained
as KBr discs on Perkin Elmer 2000 FTIR spectrophotometer in the
range 4000–370 cmÀ1 1H and 13C NMR spectra were recorded on
.
400 MHz and 101 MHz Bruker NMR spectrophotometers respec-
tively. Chemical shifts are given in ppm (d scale) relative to tetra-
methylsilane (for 1H and 13C nuclei).
2.1. Synthesis of ammonium N-ethyl-N-phenyldithiocarbamate, L1
The ligand ammonium N-ethyl-N-phenyldithiocarbamate [L1]
was prepared according to a reported procedure with some modi-
fications [18]. To a mixture of 6.44 mL (0.05 mol) of N-ethyl aniline
and concentrated aqueous ammonia (15 mL) in ice, was added
3.00 mL (0.05 mol) of ice cold carbon disulfide. The yellowish green
liquid mixture was stirred for 6–7 h given yellowish white solid
product which was filtered by suction and rinsed three times with
cold ethanol (75 mL) given thermally unstable, moisture and
* Corresponding author. Tel.: +27 40 602 2055; fax: +27 40 602 2094.
E-mail address: pajibade@ufh.ac.za (P.A. Ajibade).
0277-5387/$ - see front matter Ó 2010 Elsevier Ltd. All rights reserved.
doi:10.1016/j.poly.2010.01.011

1432
D.C. Onwudiwe, P.A. Ajibade / Polyhedron 29 (2010) 1431–1436
air-sensitive, ammonium salt of N-ethyl-N-phenyldithiocarbamate
which was stored in the refrigerator. Attempts to obtain elemental
analyses were hindered by rapid decomposition.
0.265 g (75%) M.p. 204–206 °C. 1H NMR (CDCl3) d = 7.57–7.11 (m,
5H, C6H5), 4.21 (td, J = 16.4, 9.3, 3H, CH2), 2.17 (s, 1H, CH2), 1.95–
1.64 (m, 2H, CH2), 1.47–1.07 (m, 7H, CH3). 13C NMR (CDCl3) d
130.87, 128.82, 128.27 (–C6H5); 68.18 –CH2), 29.24 (–CH2), 19.92,
Yield: 6.8 g (56%). Selected IR,
m
(cmÀ1) L1: 1456 (C@N), 1261
(N–H).
(C2–N), 982, 1056 (S@C = S), 3422 (N–H), 1601
r
(–CH2), 14.04 (–CH3). Selected IR, m
(cmÀ1): 1454 (C@N), 1159
(C2–N), 950, (C@S). Anal. Calc. for C22H28N2S4Cd (561.13): C,
47.09; H, 5.03; N, 4.99; S, 22.85. Found: C, 46.78; H, 4.87; N,
5.19; S, 22.62%.
2.2. Synthesis of ammonium N-butyl-N-phenyldithiocarbamate, L2
The ligand, ammonium N-butyl-N-phenyldithiocarbamate L2,
was prepared using the same procedure for L1. A mixture of
8.20 mL (0.10 mol) N-butyl aniline and concentrated aqueous
ammonia (15 mL) was allowed to attain ice temperature in a round
bottom flask. To this mixture, 3.00 mL (0.05 mol) of ice cold carbon
disulfide was added and stirred for 8 h. The yellowish solid which
separated was filtered and rinsed three times with ice cold ethanol
(75 mL). The product was stored in the refrigerator.
HgL22: complex was obtained as greenish-ash solid. Yield:
0.330 g (81%) M.p. 164–166. 1H NMR (CDCl3) d = 7.31–7.22 (m,
5H, C6H5), 4.19–3.97 (m, 2H, CH2), 2.17 (s, 1H, CH2), 1.70 (s, 1H,
CH2), 1.69–0.94 (m, 10H, CH3). 13C NMR (CDCl3) d 129.93, 129.05,
126.82 (–C6H5), 60.48(–CH2), 29.54 (–CH2), 20.27 (–CH2), 14.10
(–CH3). Selected IR,
m
(cmÀ1): 1455 (C@N), 1068 (C2–N), 942
(C@S). Anal. Calc. for C22H28N2S4Hg (649.31): C, 40.70; H, 4.35; N,
4.31; S, 19.75. Found: C, 41.02; H, 4.12; N, 3.99; S, 19.52%.
Yield: 7.5 g (62%). Selected IR,
m
(cmÀ1) L2: 1456 (C@N), 1254
(C2–N), 929, 1055 (S@C@S), 3423 (N–H), 1601 r(N–H).
2.4. Crystal structure determination and refinement
2.3. Preparation of complexes
Crystal structure determinations for the zinc complexes struc-
tures were collected on a Nonius Kappa-CCD diffractometer using
The preparation of complexes was carried out at room tempera-
ture. About 15 mL aqueous solution of the metal salt (MCl2,
0.625 mmol) [M = Zn, Cd, Hg], was added to 15 mL aqueous solution
of ammonium N-alkyl-N-phenyldithiocarbamate (1.250 mmol), the
white precipitate which immediately formed was stirred for about
45 min. to ensure complete reaction. The solid precipitates were fil-
tered off, rinsed with distilled water and dried at ambient temper-
ature over CaCl2.
graphite monochromated Mo K
a radiation (k = 0.71073 Å). Tem-
perature was controlled by an Oxford Cryostream cooling system
(Oxford Cryostat). The strategy for the data collections was evalu-
ated using the Bruker Nonius ‘‘COLLECT” program. Data were scaled
and reduced using DENZO-SMN software [19]. An empirical
absorption correction using the program SADABS [20] was applied.
Both structures were solved by direct methods and refined
employing full-matrix least-squares with the program SHELXL-97
[21] refining on F2. Packing diagrams were produced using the pro-
gram PovRay and graphic interface X-seed [22]. For the structure of
[Zn2(C9H10NS2)4], all non-hydrogen atoms were refined anisotrop-
ically. For the structure of [Zn2(C11H14NS2)4], all the non-hydrogen
atoms except a number of carbon atoms (C8, C9A, C10A, C9B, C10B
and C16) were refined anisotropically. These carbon atoms have
relatively high temperature factors (0.06 < Uiso > 0.16) due to high
thermal motions and therefore were refined isotropically. For both
two structures, all the hydrogen atoms were placed in idealized
positions in a riding model with Uiso set at 1.2 or 1.5 times those
of their parent atoms and fixed C–H bond lengths. Both structures
were refined successfully with final R = 0.0321 for [Zn2(C9H10NS2)4]
and R = 0.0433 for [Zn2(C11H14NS2)4].
Zn2L14: complex was obtained as white solid. Yield: 0.196 g,
(69%), M.p. 210–212 °C.
1H NMR (CDCl3) d = 7.67–7.32 (m, 4H, C6H5), 4.21 (dd, J = 14.2,
6.9, 2H, CH2), 2.17 (s, 1H, CH3). 13C NMR (CDCl3) d 129.57,
128.37, 126.70, (C6H5), 68.07 (–CH2), 12.38 (–CH3).
Selected IR, m
(cmÀ1): 1456 (C@N), 1157 (C2–N), 959 (C@S). Anal.
Calc. for C18H20N2S4Zn (457.99): C, 47.21; H, 4.40; N, 6.12; S, 28.00.
Found: C, 47.08; H, 4.38; N, 6.14; S, 28.01%. Recrystallization of
complex, Zn2L14, in dichloromethane/methanol (1:1) solvent mix-
ture gave colorless single crystals suitable for X-ray analysis.
CdL12: complex was obtained as white solid. Yield: 0.223 (71%),
M.p. 278–280 °C. 1H NMR (DMSO) d 7.42 (t, J = 7.2, 1H, C6H5), 7.40–
7.20 (m, 2H, C6H5), 4.15 (q, J = 7.0, 1H, CH2), 2.50 (d, J = 1.7, 8H,
CH3). Selected IR,
m
(cmÀ1): 1454 (C@N), 1159 (C2–N), 957 (C@S).
Anal. Calc. for C18H20N2S4Cd (505.02): C, 42.81; H, 3.99; N, 5.55;
3. Results and discussion
S, 25.39. Found: C, 43.00; H, 4.03; N, 5.63; S, 25.78%.
HgL12: complex was obtained as pale green solid. Yield: 0.240 g
(65%), Dec/M.p. 150/210 °C. 1H NMR (CDCl3) d 7.54–7.21 (m, 8H,
C6H5), 7.26 (s, 4H, C6H5), 4.17 (dd, J = 14.2, 7.2, 3H, CH2), 2.17 (s,
1H, CH3). 13C NMR (CDCl3) d 130.01, 129.29, 126.84 (C6H5); 56.00
3.1. Synthesis
The ligands L1 and L2 are unstable at ambient temperature, and
more stable under refrigerator’s condition, L2 is relatively more
stable than L1 at both conditions. The solubility of these ligands
was found to reduce with increased number of carbon on the nitro-
gen atom. Reaction of two molar equivalents of L1 and L2 with
1 mol of ZnCl2, CdCl2 and HgCl2 at room temperature gave the
respective metal complexes. All compounds are air-stable, soluble
in chloroform, and dichloromethane; and insoluble in n-hexane,
pentane, methanol and 2-propanol. The analytical and spectro-
scopic data are consistent with the proposed formulation for the
complexes.
(–CH2), 12.40 (–CH3). Selected IR,
m
(cmÀ1): 1455 (C@N), 1281
(C2–N), 981 (C@S). Anal. Calc. for C18H20N2S4Hg (593.20): C,
36.45; H, 3.40; N, 4.72; S, 21.62. Found: C, 37.29; H, 3.68; N,
4.96; S, 22.48%.
Zn2L24: complex was obtained as white solid. Yield: 0.267 g
(42%) M.p. 198–200 °C. 1H NMR (CDCl3) d = 7.40 (dt, J = 13.6, 7.2,
5H, C6H5), 7.25 (d, J = 6.5, 6H, C6H5), 4.21–4.05 (m, 3H, CH2), 2.17
(s, 1H, CH2), 1.92–1.53 (m, 9H, CH2), 1.35 (dd, J = 14.7, 7.3, 5H,
CH3). 13C NMR (CDCl3) d 129.51, 128.57, 126.67, (C6H5); 58.86
(–CH2), 29.24 (–CH2), 19.85(–CH2), 13.70 (–CH3). Selected IR,
m
(cmÀ1): 1455 (C@N), 1063 (C2–N), 940 (C@S). Anal. Calc. for
C22H28N2S4Zn (514.10): C, 51.40; H, 5.49; N, 5.45; S, 24.94. Found:
C, 51.07; H, 5.12; N, 5.26; S, 24.46%. Complex Zn2L24, was recrystal-
lized in dichloromethane/methanol (3:1) solvent mixture given
colorless single crystals suitable for X-ray analysis.
3.2. Spectroscopic analysis
The infra red spectra of the ligands and their corresponding me-
tal complexes were compared and assigned on the basis of careful
comparison. In the ligands, the band in the range 1453–1456 cmÀ1
CdL22: complex was obtained as white solid and recrystallized
in dichloromethane/ethyl acetate (2:1) solvent mixture. Yield:
and 1063–1261 cmÀ1 are attributed to the
v(C–N) and v(C2–N)

D.C. Onwudiwe, P.A. Ajibade / Polyhedron 29 (2010) 1431–1436
1433
Table 2
R
N
Selected bond length (Å) and bond angle (°) for [Zn2(C9H10NS2)4].
S
S
Zn(1)–S(4)
Zn(1)–S(1)
Zn(1)–S(3)#1
Zn(1)–S(2)
Zn(1)–S(3)
S(1)–C(9)
S(2)–C(9)
S(3)–C(10)#1
N(1)–C(9)
2.3501(7)
2.3659(6)
2.4007(5)
2.4421(6)
2.7513(6)
1.730(2)
1.740(2)
2.4007(5)
1.334(3)
1.454(3)
1.490(4)
1.4937(10)
1.326(3)
1.448(3)
1.483(3)
S(4)–Zn(1)–S(1)
S(4)–Zn(1)–S(3)#1
S(1)–Zn(1)–S(3)#1
S(4)–Zn(1)–S(2)
S(1)–Zn(1)–S(2)
S(3)#1–Zn(1)–S(1)
S(4)–Zn(1)–S(3)
S(1)–Zn(1)–S(3)
S(3)#1–Zn(1)–S(3)
S(2)–Zn(1)–S(3)
C(9)–S(1)–Zn(1)
C(9)–S(2)–Zn(1)
C(10)–S(1)–Zn(1)#1
C(10)–S(3)–Zn(1)
Zn(1)#1–S(3)–Zn(1)
C(10)–S(4)–Zn(1)
136.12(2)
C
M
C
N
R
104.03(2)
117.03(2)
107.33(2)
75.59(2)
105.43(2)
70.724(19)
95.734(19)
88.847(17)
165.50(2)
84.29(8)
82.30(8)
100.73(7)
78.67(7)
91.153(17)
91.70(8)
S
S
M = Cd, Hg and R = C2H5, C4H9
Fig. 1. Proposed structure for some of the complexes.
N(1)–C(1)
N(1)–C(7A)
N(1)–C(7B)
N(2)–C(10)
N(2)–C(13)
N(2)–C(11)
Table 1
Summary of crystal data and structure refinement.
Compound
[Zn2(C9H10NS2)4]
C36H40N4S8Zn2
915.94
173(2)
0.71073
[Zn2(C11H14NS2)4]
C44H56N4S8Zn2
1028.15
173(2)
0.71073
Empirical formula
Formula weight
Temperature (K)
Wavelength
ꢀ
Space group
P21/n
P1
Unit cell dimensions
Table 3
Selected bond length (Å) and bond angle (°) for [Zn2(C11H14NS2)4].
a (Å)
b (Å)
c (Å)
b (°)
8.7163(3)
10.5618(3)
12.0172(3)
66.341(2)
79.577(2)
995.26(5)
1
1.528
1.657
472
11.0542(2)
14.8044(3)
15.1778(3)
91.7050(10)
90
2482.76(8)
2
1.375
Zn(1)–S(4)
Zn(1)–S(1)
Zn(1)–S(3)#1
Zn(1)–S(2)
S(1)–C(11)
S(2)–C(11)
S(3)–C(12)
S(3)–Zn(1)#1
S(4)–C(12)
N(1)–C(11)
N(1)–C(1)
2.3119(7)
2.3353
2.3607
2.4396
1.732
1.714
1.741
2.3607
1.719
1.336
S(4)–Zn(1)–S(1)
S(4)–Zn(1)–S(3)#1
S(1)–Zn(1)–S(3)#1
S(4)–Zn(1)–S(2)
S(1)–Zn(1)–S(2)
S(3)#1–Zn(1)–S(2)
C(11)–S(1)–Zn(1)
C(11)–S(2)–Zn(1)
C(12)–S(3)–Zn(1)#1
C(12)–S(4)–Zn(1)
N(1)–C(11)–S(2)
N(1)–C(11)–S(1)
S(2)–C(11)–S(1)
N(2)–C(12)–S(4)
N(2)–C(12)–S(4)
S(4)–C(12)–S(3)
131.73(3)
106.47(3)
117.47(3)
108.36(3)
76.32(3)
108.36(3)
84.30(10)
81.47(9)
103.21(9)
96.36(9)
120.9(2)
121.3(2)
117.83(16)
118.9(2)
c
(°)
Volume (Å3)
Z
Dcalc (Mg/m3)
Absorption coefficient (mmÀ1
F (0 0 0)
)
1.337
1072
Crystal size (mm)
h Range (°)
Limiting indices
0.20 Â 0.18 Â 0.16 0.14 Â 0.12 Â 0.08
3.10–28.28
À11 ꢀ h ꢀ 11,
À14 ꢀ k ꢀ 14,
À16 ꢀ 1 ꢀ 16
31 692
3.31–28.27
À14 ꢀ h ꢀ 14,
À19 ꢀ k ꢀ 19,
À20 ꢀ 1 ꢀ 20
93 202
1.444
1.478
1.328
1.450
N(1)–C(7)
N(2)–C(12)
N(2)–C(17)
N(2)–C(13)
Reflections collected
Independent reflection
1.483
121.7(2)
119.32(15)
4931
6147
[R(int) = 0.0341]
Full-matrix least-
squares on F2
99.8
4931/1/246
1.054
R1 = 0.0321,
wR2 = 0.0676
R1 = 0.0427,
wR2 = 0.0728
[R(int) = 0.0517]
Full-matrix least-
squares on F2
99.8
6147/5/251
1.042
R1 = 0.0433,
wR2 = 0.1048
R1 = 0.0620,
wR2 = 0.1158
Refinement method
Completeness to h = 28.28
Data/restraints/parameters/
Goodness-of-fit on F2
mate through the S atom. The absence of the bands around 3422
and 1601 cmÀ1 in the complexes which are attributed to
(N–H)
and (N–H) in the ligands confirm the ammonium ion is displaced
by the metal atom. The
Final R indices [I > 2
r(I)]
v
r
R indices (all data)
m
(M–S) peaks occurred in the far-IR region,
300–400 cmÀ1, and depend on the nature of the metal ion and the
substituents attached with the nitrogen [26].
Largest difference in peak and hole
(e ÅÀ3
0.670 and À0.739 0.925 and À0.843
)
The 1H NMR chemical shifts around 2.17 and 4.20 ppm found
in all the spectra are ascribed to methyl and methylene carbon
linked directly with N atoms of the dithiocarbamates. It is found
that the coordinated dithiocarbamate group is more electronega-
tive than in the case where there is no coordination. These could
account for the downfield shift of about <1 ppm usually observed
when the peaks of the metal complexes are compared with the
salts of their appropriate acids [27]. The signals observed in the
region d 7.25–7.67 ppm are attributed to the protons of phenyl
rings. The coupling constants were not observed in most com-
plexes because the phenyl protons are displayed as a multiplet.
A feature of the 13C NMR spectra of all the complexes is the
resonances from the alkyl substituents. The nitrogen-bound
stretching vibration [23] respectively. Studies on alkyl dithiocarba-
mates have shown that the lengthening of the alkyl chain is accom-
panied by a decrease in
m(C–N) although the m(C–S) remains
unaltered as it has been found to be insensitive to the nature of al-
kyl substituents [24]. The lower values observed in this prominent
and characteristic peaks in the ligands can be ascribed to the effect
of the size of the butyl group on the nitrogen. The symmetrical and
unsymmetrical vibrations observed as two peaks in the range 929–
960 and 1054–1056 cmÀ1, respectively, in the ligands gave way to
a single peak in the complexes in the range 940–990 cmÀ1, belong-
ing to the
v(C–S) stretching vibration [23,25]. This showed that the
a-carbon is shifted downfield with respect to the other sig-
dithiocarbamates act as bidentate ligands based on the criterion of
Bonati and Ugo [23] which uses the number of bands observed in
the region 950–1050 cmÀ1 to determine the nature of the coordi-
nation of the ligand as either bidentate symmetrical or monoden-
tate asymmetrical. The proposed formulation for the Cd(II) and
Hg(II) complexes is shown in Fig. 1.
nals, being found between 55 ppm and 68 ppm. This could be as-
cribed to the effect of the aromatic ring, pushing the peaks
downfield, which typically are found between 43 and 57 ppm in
alkyldithiocarbamates. Further methylene groups appear between
20 and 40 ppm, being shifted to higher field upon increasing dis-
tance from the nitrogen center, while the end methyl groups are
found between 14 and 12 ppm [28]. The aromatic carbons appear
between 120 and 130 ppm.
In the complexes, the observed decrease of about 100 cmÀ1 in
the v(C–S) indicates that the metal ions bond to the dithiocarba-

1434
D.C. Onwudiwe, P.A. Ajibade / Polyhedron 29 (2010) 1431–1436
Fig. 2. Crystal structure of [Zn2(C9H10NS2)4].
3.3. X-ray crystallography
Zn(1)–S(23) with 107.33(2)° and 95.73(2)° are significantly differ-
ent from the ideal value of 90°. The angles described by atoms in
the equatorial positions should be close to 120°; the angles involv-
ing S(3)#1 atoms [104.03(2) and 117.03(2)] are smaller than the
ideal value (120°) but the S(4)–Zn(1)–S(1) bond angle is somewhat
larger, 136.12(2)°, most probably due to steric requirements of the
ligands and the S(2)–Zn(1)–S(3) bond angle of 165.50(2)° deviate
from the ideal value of 180°.
The zinc complexes were structurally determined by X-ray
crystallography. The crystallographic and measurement data are
shown in Table 1 and representative bond lengths and bond angles
are listed in Table 2 and 3. Figs. 2 and 3 present thermal ellipsoid
representations of the complexes respectively and the schematic
drawing of the crystal packing are presented in Figs. 4 and 5. In
dithiocarbamate metal complexes, the planarity of the MS2CNC2
unit is a key feature of the crystal structure of metal-bound dithio-
carbamates. That is, all seven atoms lie approximately in a plane
and thus dithiocarbamates are best considered as being stereo-
chemically rigid hence sterically non-demanding [29]. The
In [Zn2(C11H14NS2)4], the structure consist of discrete molecular
species in which the zinc atom have four coordinate geometry. The
[Zn2(C11H14NS2)4] was crystallized in the space group P21/n with
Z = 2. The molecule is located at the center of inversion at position
d. One of the C4H9 moieties of the asymmetric unit is disordered
over two positions with 50% s.o.f for C9A and C10A, another 50%
s.o.f. for C9B and C10B. The Zn atom is tetrahedrally coordinated
to one molecules of butyl-phenyl dithiocarbamate functioning as
bidentate ligands through the S-atom. The other sites are occupied
by the bridging-chelating dithiocarbamate ligands to give intercon-
nected eight-member rings, each containing two zinc atoms and
two bridging dithiocarbamates. The Zn–S(1) [2.3353(8) Å] and Zn–
S(2) [2.4396(7) Å] bond distances indicate that the dithiocarbamate
acts as a bidentate chelating ligands. The Zn–S bonds vary from
2.3353(8) Å for the non-bridging chelate ligand to 2.3607(7) Å for
the bridging-chelating ligand. Two of the shortest metal–sulfur dis-
tances are formed by S atoms of one of the chelating moieties while
the S atoms of the other chelating-bridging moiety produce both
long and short M–S distances. Sharing of an S atom in the complexes
gives rise to a dimeric unit in which one of the ligand form a chelate
ring and the other is coordinated to two Zn2+ ions.
ꢀ
[Zn2(C9H10NS2)4] was crystallized at P1 with Z = 1. The molecule
of [Zn2(C9H10NS2)4] is located at the center of inversion in which
one of the C2H5 moieties of the asymmetric unit is disordered over
two positions with C7A and C8A having site occupancy factor
(s.o.f.) of 60.8%, C7B and C8B having s.o.f. of 39.2%. The molecular
structure consist of discrete molecular species in which the metal
atom is coordinated to two dithiocarbamate molecules and bridge
the S-atom of one of the dithiocarbamate on the adjacent molecule.
The X-ray structure of [Zn2(C9H10NS2)4] revealed that the Zn atoms
are in a distorted trigonal bipyramidal environment. The distortion
of the regular trigonal bipyramidal geometry is mainly due to small
bite of the dithiocarbamate ligands, whose S(1)–Zn(1)–S(2) and
S(3)–Zn(1)–S(4) chelate angles are 75.59(2)° and 70.724(19)°,
respectively, which deviate significantly from 90°. These deviations
produce bond angle values that are different from the expected.
Therefore the other angles such as S(4)–Zn(1)–S(2) and S(1)–

D.C. Onwudiwe, P.A. Ajibade / Polyhedron 29 (2010) 1431–1436
1435
Fig. 3. Crystal structure of [Zn2(C11H14NS2)4].
Fig. 4. Schematic drawing of the crystal packing of [Zn2(C9H10NS2)4].

1436
D.C. Onwudiwe, P.A. Ajibade / Polyhedron 29 (2010) 1431–1436
Fig. 5. Schematic drawing of the crystal packing of [Zn2(C11H14NS2)4].
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CCDC 725036 and 725037 contain the supplementary crystallo-
graphic data for this paper. These data can be obtained free of
charge via http://www.ccdc.cam.ac.uk/conts/retrieving.html, or
from the Cambridge Crystallographic Data Center, 12 Union Road,
Cambridge CB2 1EZ, UK; fax: (+44) 1223-336-033; or e-mail:
deposit@ccdc.cam.ac.uk.
Acknowledgements
The authors gratefully acknowledge the contribution of Dr.
Hong Su and financial support of GMRDC, University of Fort Hare,
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