New antimony(III) bromide complexes with thioamides: Synthesis, characterization, and cytostatic properties

Article abstract of DOI:10.1021/ic8019205

New antimony(III) bromide complexes with the heterocyclic thioamides, thiourea (TU), 2-mercapto-1-methylimidazole (MMl), 2-mercapto-benzimidazole (MBZlM), 2-mercapto-5-methyl-benzimidazole (MMBZIM), 5-ethoxy-2-mercapto- benzimidazole (EtMBZIM), 2-mercapto

Full text of DOI:10.1021/ic8019205

Inorg. Chem. 2009, 48, 2233-2245
New Antimony(III) Bromide Complexes with Thioamides: Synthesis,
Characterization, and Cytostatic Properties
†
Ibrahim I. Ozturk, Sotiris K. Hadjikakou,* Nick Hadjiliadis,* Nikolaos Kourkoumelis, Maciej Kubicki,
,†
,†
‡
§
|
Anastasios J. Tasiopoulos, Hanadi Scleiman, Mirela M. Barsan, Ian S. Butler, and Jan Balzarini
⊥
⊥
⊥
#
Section of Inorganic and Analytical Chemistry, Department of Chemistry, UniVersity of Ioannina,
4
4
6
5110 Ioannina, Greece, Medical Physics Laboratory, Medical School, UniVersity of Ioannina,
5110 Ioannina, Greece, Faculty of Chemistry, Adam Mickiewicz UniVersity, Grunwaldzka 6,
0-780 Poznan′, Poland, Department of Chemistry, UniVersity of Cyprus, 1678 Nicosia, Cyprus,
Department of Chemistry, McGill UniVersity, 801 Sherbrooke Str.West, Montreal, Quebec H2A
2
K6, Canada, and Katholieke UniVersiteit LeuVen, Rega Institute for Medical Research,
Minderbroedersstraat 10, B-3000 LeuVen, Belgium
Received October 8, 2008
New antimony(III) bromide complexes with the heterocyclic thioamides, thiourea (TU), 2-mercapto-1-methylimidazole (MMI),
-mercapto-benzimidazole (MBZIM), 2-mercapto-5-methyl-benzimidazole (MMBZIM), 5-ethoxy-2-mercapto-benzimidazole
EtMBZIM), 2-mercapto-3,4,5,6-tetrahydro-pyrimidine (tHPMT), 2-mercaptopyridine (PYT), 2-mercapto-thiazolidine (MTZD),
-methyl-2-mercaptobenzothiazole (MMBZT), and 2-mercaptopyrimidine (PMTH) of formulas [SbBr (TU) ] (1), [SbBr (MMI)
MeOH} (5), {[SbBr (µ
(MMBZT) ] (9), and
]} (10) have been synthesized and characterized by elemental analysis, conductivity measurements,
FTIR spectroscopy, FT-Raman spectroscopy, TG-DTA analysis, and X-ray powder diffraction. The crystal structures of
2
(
3
3
2
3
2
]
+
-
(2), {[SbBr
2
(MBZIM)
4
] [Br] H
2
O} (3), {[SbBr
2
(µ
2
-Br)(MMBZIM)
2
]
2
} (4), {[SbBr
2
(µ
2
-Br)(EtMBZIM)
2
]
2
3
2
-
S-tHPMT)(tHPMT)]
n
} (6), {[SbBr
2
(µ -Br)(PYT)
2
2
)
n
} (7), {[SbBr
2
(µ -Br)(MTZD)
2
2
]
n
} (8), [SbBr
3
2
2-
2+
{
[SbBr
5
] [(PMTH )
2
3
, 4, 5, 6, 7, 8, and 10 were also determined by X-ray diffraction. In 3, four sulfur atoms from thione ligands and two
+
bromide ions form an octahedral (O ) cationic [SbS
h
4
Br
2
] species in which the two bromide anions lie at axial positions.
A third bromide counteranion neutralizes the whole complex. 4 and 5 are dimers, whereas 6, 7 and 8 are polymers, built
up by monomeric units of square pyramidal (SP) geometry around the metal center, which were formed by two sulfur
2-
5 n
atoms of thioamide ligands and three bromide ions. Finally, 10 is ionic salt containing 1D polymeric network of {[SbBr ] }
-
2+
anions and [(PMTH )2] counter cations in the lattice. The complexes showed mostly a moderate cytostatic activity
against a variety of tumor cell lines.
1
a,4-6
1
. Introduction
ion Sb(III).
This redox behavior of the metal center is
7
found to affect the geometry of the complex core, whereas
the geometric transformations, which may take place during
this process, may involve the intermolecular interactions that
play an important role in the solid-state arrangement, the
Antimony-based metallotherapeutic drugs have been the
1
-5
major therapeutic compounds for leishmania for years.
The mechanism of their antileishmanial activity is still poorly
understood.
4
,5
It has been proposed that the relatively
nontoxic Sb(V) acts only as a prodrug and it is reduced into
the more toxic trivalent form near or in the action site and
therefore the antileishmanial activity is due to the trivalent
(
1) (a) Yan, S.; Lan, L.; Sun, H. Antimony in Medicine, in Metallothera-
peutic drugs and Metal-based diagnostic Agents - The Use of Metals
in Medicine; Gielen, M, Tiekink, E. R. T., Eds.; Willey: England,
2
005. (b) Martidale The Extra Pharmacopoeiam, 28th ed.; Raynolds,
J. E. F., Ed.; The Pharmaceutical Press: London, 1982. (c) Marsden,
P. D. ReV. Soc. Bras. Med. Trop 1985, 18, 187–198. Pentavalent
antimonials: old drugs for new diseases. (d) Herwaldt, B. L. Lancet
1999, 354, 1191–1199.
*
To whom correspondence should be addressed: E-mail: shadjika@uoi.gr.
Tel: xx30-26510-98374(S.K.H.), E-mail: nhadjis@uoi.gr. Tel: xx30-26510-
9
8420. Fax: xx30-26510-98786 (N.H.).
†
Department of Chemistry, University of Ioannina.
Medical School, University of Ioannina.
Faculty of Chemistry, Adam Mickiewicz University.
Department of Chemistry, University of Cyprus.
Department of Chemistry, McGill University.
Katholieke Universiteit Leuven, Rega Institute for Medical Research.
(2) Tiekink, E. R. T. Crit. ReV. Oncol./Hematol. 2002, 42, 217–224.
(3) Yan, S.; Li, F.; Ding, K.; Sun, H. J. Biol. Inorg. Chem. 2003, 8, 689–
697.
(4) Guo, Z.; Sadler, P. J. AdV. Inorg. Chem. 2000, 49, 183–306.
(5) Sun, H.; Yan, S. C.; Cheng, W. S. Eur. J. Biochem. 2000, 267, 5450–
5457.
‡
§
|
⊥
#
1
0.1021/ic8019205 CCC: $40.75  2009 American Chemical Society
Inorganic Chemistry, Vol. 48, No. 5, 2009 2233
Published on Web 01/26/2009

Ozturk et al.
Scheme 1
In this article, we report the structural and spectroscopic
characterization of 10 new antimony(III) tribromide com-
plexes with the heterocyclic thioamides (Scheme 3), thiourea
(
TU), 2-mercapto-1-methylimidazole (MMI), 2-mercapto-
benzimidazole (MBZIM), 2-mercapto-5-methyl-benzimida-
zole (MMBZIM), 5-ethoxy-2-mercapto-benzimidazole (Et-
MBZIM), 2-mercapto-3,4,5,6-tetrahydro-pyrimidine (tHPMT),
2
3
-mercaptopyridine (PYT), 2-mercapto-thiazolidine (MTZD),
-methyl-2-mercaptobenzothiazole (MMBZT), and 2-mer-
Scheme 2
captopyrimidine (PMTH) of formulas [SbBr
3
-
(TU)
2
] (1),
O} (3),
-Br)(EtMB-
-S-tHPMT)(tHPMT)] } (6),
} (7), {[SbBr (µ -Br)(MTZD) } (8),
]} (10).
+
[
SbBr
[SbBr
ZIM)
[SbBr
SbBr (MMBZT)
3
(MMI)
(µ -Br)(MMBZIM)
MeOH} (5), {[SbBr
(µ -Br)(PYT)
5 2 2
] (9), and {[SbBr ] [(PMTH )
2
] (2), {[SbBr
2
(MBZIM)
} (4), {[SbBr
(µ
4
] [Br] H
2
{
2
2
2
]
2
(µ
2 2
2
]
2
3
2
n
{
[
2
2
]
2 n
2
2
-
2 n
]
2
+
3
2
These new complexes exhibit interesting structural motifs.
2
solvation effect, and the 5s lone pair of electrons located
7
on Sb(III) as well. Sulfur containing ligands, such as thiones/
Results and Discussion
8
9
10
thiols, thioethers, dithiocarbamates, have been used to
prepare stable Sb(III) bromide complexes. The reports on
structural characterization of antimony(III) bromide com-
plexes with thione/thiol ligands are rare in the literature.
General Aspects. Antimony(III) complexes 1-10 have
been synthesized by reacting the appropriate thioamide with
antimony(III) bromide (SbBr ) in methanolic/dichloromethane,
3
methanolic/acetonitrile, or dichloromethane solutions, as
shown by eqs I-IV.
All of the complexes are formed as air-stable powders.
Crystals of 3 suitable for X-ray analysis were grown by slow
evaporation of a methanol/dichloromethane (1:1) solution,
whereas crystals of 4, 6, and 8 were grown from acetonitrile
solutions and those of 5, 7, and 10 were obtained from
methanol/acetonitrile solutions.
3
Me
1
Me
Me
These include [Sb(k -Tm )(k -Tm )Br] (Tm
)
8a
hydrotris(methimazolyl)borate), [SbBr(dmit)(THF)]
n
(dmit
{[Ph-CHd
]SbBr, and [Sb(mtsc)Br
N’-[1-(2-pyridyl)ethylidene]morpholine-4-
8
b
)
2-thioxo-1,3-dithiole-4,5-dithiolato),
8
c
8d
CH(Ph)S]SbBr}, [S(C
Hmtsc)
6
H
4
S)
2
2
]
(
8
e
carbothiohydrazide). Up to now, antimony(III) bromide
complexes with thione/thiole were found to adopt octahedral
pseudotrigonal-bipyramidal
(Scheme 1).
Recently, we described a series of antimony(III) chloride
complexes with thione ligands. These complexes adopt
either octahedral (O ) or square pyramidal (SP) geometries
Scheme 2) and the O geometries exhibit selective antipro-
liferative activity against HeLa cells. Moreover, the SP
complex with trans-Cl, trans-S, is more active against human
T-lymphocyte cells (Molt4/C8, CEM) than the other com-
8
a
(
O
h
)
and
(Ψ-TBP)
8
b-d
CH OH ⁄ CH Cl
2
structures
3
2
SbBr + 4MBZIM
8
3
1
1
+
-
{
[Sb(MBZIM) Br ] Br H O} (I)
h
4 2 2
3
(
h
(
a) CH Cl , re-cryst. CH CN
2 2 3
nSbBr + 2nHL.
8
3
(b) CH3OH⁄CH3CN
[
SbBr (µ -Br)(HL) ] (II)
2 2 2 n
1
1
h
plexes with SP or O geometries (Scheme 2). Thus, the
(
a) n ) 2 and HL ) MMBZIM (4), n ) infinite and HL)
MTZD (8) or MMI (2)
b) n ) 2 and HL ) EtMBZIM (5), n ) infinite and HL)
study of the structural behavior of the complexes derived
from the reaction between antimony(III) halides and thiones
is a matter of significant importance.
(
PYT (7) or MMBZT (9) or TU (1)
(
(
(
6) Shaked-Mishan, P.; Ulrich, N.; Ephros, M.; Zilberstein, D. J. Biol.
CH Cl , re-cryst. CH CN
2
2
3
Chem. 2001, 276, 3971–3976.
nSbBr + 2ntHPMT
8
3
7) Avarvari, N.; Faulques, E.; Fourmigue, M. Inorg. Chem. 2001, 40,
2
570–2577.
8) (a) Dodds, C. A.; Reglinski, J.; Spicer, M. D. Chem.sEur. J. 2006,
2, 931–939. (b) Abrantes, L. T.; Comerlato, N. M.; Ferreira, G. B.;
[SbBr (µ -S-tHPMT)(tHPMT)] (III)
3 2 n
1
6
Alan Howie, R.; Wardell, J. L. Inorg. Chem. Commun. 2006, 9, 522–
CH OH ⁄ CH CN
3
3
5
25. (c) Buchwald, S. L.; Flsher, R. A.; Davis, W. M. Organometallics
2-
+
nSbBr + HPMT
8 {[SbBr ] [(H PMT) ] }
5 n 2 2
3
1
989, 8, 2082–2084. (d) Alvarado-Rodriguez, J. G.; Andrade-Lopez,
1
0
N.; Gonzalez-Montiel, S.; Merino, G.; Vela, A. Eur. J. Inorg. Chem.
2
003, 3554, 356. (e) Kasuga, N. C.; Onodera, K.; Nakano, S.; Hayashi,
(
IV)
K.; Nomiya, K. J. Inorg. Biochem. 2006, 100, 1176–1186.
9) Barton, A. J.; Hill, N. J.; Levason, W.; Reid, G. J. Chem. Soc., Dalton
Trans. 2001, 1621, 1627.
(
Thermal Analysis. Scheme 4 summarizes the thermal
decomposition of 1-10 based on thermal analysis in a
flowing nitrogen atmosphere. Three main decomposition
(
10) (a) Zhai, J.; Pan, Q.-X.; Yin, H.-D.; Li, F.; Wang, D.-Q. Acta
Crystallogr. 2007, E63, m1356–m1357. (b) Sun, Y.; Li, Y.; Cui, X.;
Lang, X. Acta Crystallogr. 2007, E63, m3132-m3132. (c) Yin, H.-
D.; Zhai, J.; Sun, Y.-Y.; Wang, D.-Q. Polyhedron 2008, 27, 663–
h
pathways were observed for the O (A), dimeric (B), and
6
70.
polymeric (C) types of complexes.
(
11) Ozturk, I. I.; Hadjikakou, S. K.; Hadjiliadis, N.; Kourkoumelis, N.;
The decomposition of the octahedral ionic salt 3 sums up
to a total of 80% mass loss and it is connected with three
Kubicki, M.; Baril, M.; Butler, I. S.; Balzarini, J. Inorg. Chem. 2007,
4
6, 8652–8661.
2234 Inorganic Chemistry, Vol. 48, No. 5, 2009

New Antimony(III) Bromide Complexes
Scheme 3
Scheme 4
endothermic effects. The first stage of decomposition
(100-230 °C (5) involving 4%) is observed in case of 5
due to the solvent molecule cocrystallized (calculated 4%).
The thermal analysis of polymeric 2, 6, 7, 9, and 10 shows
one-step decomposition (100-445 °C for 2, 180-395 °C
for 6, 180-290 °C for 7, 100-243 °C for 9, and 100-425
°C for 10) involving 75% (2), 79% (6), 83% (7), 81% (9),
and 79% (10), respectively, which correspond to the simul-
taneous evolution of both two ligands and three bromine
atoms (five bromine atoms in case of 10) (calculated for 2
ligands and 3 Br (5 Br in case of 10) 79% (2), 79% (6),
79% (7), 83% (9) and 79% (10), respectively). However,
polymeric 1 and 8 are found to decompose in two steps. In
the case of 1, the first stage of decomposition (185-280 °C)
involves 47% mass loss that corresponds to the evolution of
three bromine atoms (calculated mass loss of 47%). The
second stage of decomposition (280-350 °C) involves 28%
mass loss that corresponds to the two ligands (calculated
mass loss of 30%). In the case of 8, the first stage of
decomposition (100-210 °C) involves 13% mass loss that
(
100-138 °C, 3) involves a 4.00% mass loss of two water
molecules (calculated mass loss 3.61%). The second stage
138-320 °C) involves a 59% mass loss of four MBZIM
(
ligands (calculated mass loss 60%). Finally, the third
decomposition stage (330-460 °C) of 15% mass loss
corresponds to two bromine atoms (calculated mass loss
1
6%).
The corresponding thermal analysis of the dimeric 4 and
consists of two main steps, which sum up to total mass
5
losses of 57% (4) and 65% (5), respectively. The first stage
of decomposition (80-342 °C (4) and 230-350 °C (5))
involves 46% (4) and 48% (5) and mass losses that
correspond to the evolution of two ligands (calculated mass
loss of 48 (4) and 50% (5), respectively). The second stage
of decomposition (342-450 °C (4) and 350-470 °C (5))
involves 11% (4) and 13% (5) and mass losses that
correspond to one bromine atom (calculated mass loss of
1
2% (4) and 13 (5) % respectively). An additional step
Inorganic Chemistry, Vol. 48, No. 5, 2009 2235

Ozturk et al.
1
corresponds to the evolution of one bromine atom (calculated
mass loss of 13%). The second stage of decomposition
ν(Sb-S(bridging)) at 181 cm- and a ν(Sb-S(terminal)) band at
-
1
14
197 cm , whereas the ν(Sb-Br) band is observed at 261
cm . Polymeric 8 with bridging shows only one ν(Sb-Br)
-1
14
(
210-340 °C) involves 66% mass loss that corresponds to
-
1
the two ligands (calculated mass loss of 66%).
band at 220 cm , whereas the ν(Sb-S) vibration appears
14
-1
Vibrational Spectroscopy. The IR spectra of the com-
plexes show distinct vibrational bands at 1589-1460 and
at 182 cm . 1 and 2 where no structural data are available
-
1
show ν(Sb-Br) bands at 245 and 217 cm (1) and at 251
cm (2) and ν(Sb-S) vibration bands at 193 cm (1)
and 199 (2) cm , which lead them to be classified as either
dimeric or polymeric complexes.
Conductivity Measurements. The influence of solvent
media on the complex geometries was studied by measuring
the molar conductance at 25 °C. In methanol, the complexes
exhibit molar conductances values of 174 (1), 212 (2), 254 (3),
213 (4), 216 (5), 212 (6), 315 (7), 197 (8), 212 (9), and 339
(10) cm mol Ω , respectively. In acetonitrile on the other
hand, the molar conductances measured for 1, 2, and 4-9 were
25 (1), 11 (2), 11 (4), 5 (5), 16 (6), 41 (7), 3 (8), 5 (9), and 101
(10) cm mol Ω , respectively, which correspond to
nonionic configurations, as expected (crystal structures). In case
of 3, however, a molar conductance value of 75 cm mol
was initially measured due to the presence of two ions for
this complex, which ends up to 27 cm mol
corresponds to a nonionic compound. La Manna et.al. on the
basis of conductivity measurements proposed that the equilib-
rium shown in eq V was established for antimony(III) halides
in methanolic solutions. Recently, we also reported an equi-
h
librium between ionic O and nonionic (SP) complexes (eq
VI). Because the formation mechanism of the ionic salt
complexes with O geometry involves the Sb-Br bond cleavage
(X-ray structure), such types of complexes might form through
] species and only in methanol. In acetonitrile
solutions, the compounds are neutral and so only polymeric or
dimeric Ψ-O complexes could be formed. The ∆G of the
reaction (eq V) was calculated to be -102.1 and -100.3 kcal/
mol in water and methanol solutions respectively, in favor of
this equilibrium (Computational Studies).
-
1
-1
14
-1
1
(
8
387-1219 cm , which can be assigned to V(CN) vibrations
-
1
-1 14
thioamide I and II bands) and at 1185-990 cm and
-
1
16-623 cm , which can be attributed to the V(CS)
1
1,12
vibrations (thioamide III and IV bands).
the geometrical features of 1-10 (ionic salt O
Variations in
, dimer SP,
h
or polymeric SP, see crystal structures) lead to variations in
Sb-Br and/or Sb-S bond distances due to inter- and
intramolecular interactions (crystal structures). Therefore, far-
IR spectroscopy can be a very useful tool in the geometrical
characterization of these complexes. The tentative assignment
-1
-1
-1
of the M-L vibrations are ionic salt O
h
3, which shows one
-1
13
-1
-1
-1
ν(Sb-Br) band at 228 cm
and one ν(Sb-S) vibration
-1
13
band at 275 cm . The dimeric 4 and 5 with one bridging
and one terminal bromine atom show ν(Sb-Br(bridging)) bands
-1
-1
-
1
-1
at 200 (4) and 213 (5) cm and ν(Sb-Br(terminal)) bands at
Ω
-1
13
-1
-1
-1
2
12 (4) and 232 cm (5), whereas the ν(Sb-S) vibrations
Ω
15
and
-1
13
appear at 271 (4) and 273 (5) cm . The polymeric 7 and
with bridging µ -Br show ν(Sb-Br(bridging)) bands at 208
8
2
-
1
(
7) and 200 (8) cm and ν(Sb-Br(terminal)) bands at 228 (7)
13
-
1
and 230 (8) cm , whereas the ν(Sb-S) vibration appears
-
1
13
11
at 281 (7) and 275 (8) cm . Polymeric 6 with µ
2
-S shows
-
1
a ν(Sb-S(bridging)) band at 275 cm and a ν(Sb-S(terminal)
)
-1
13
band at 282 cm , whereas the ν(Sb-Br) band was
h
-1
13
observed at 209 cm . The polymeric ionic salt 10 with
-
1
+
bridging µ
2
-Br shows ν(Sb-Br(bridging)) bands at 213 cm
the [SbBr
2
-
1
13
13
and ν(Sb-Br(terminal)) at 213 cm , whereas the ν(Sb-S)
vibration band appears at 273 cm . 1, 2, and 9 for which
no structural data are available show ν(Sb-Br) bands at 222
-1
h
-
1
-1
and 199 cm (1), 218 and 209 cm (2), and 222 and 200
-
1
13
cm (9) and ν(Sb-S) vibration bands at 272 (1), 278 (2),
-1
13
and 270 (9) cm , which classify them as either dimeric
or polymeric types of complexes in agreement with TG-DTA
data (above).
-
4
+
2
2SbBr h SbBr + SbBr
(V)
3
+
-
2
SbCl L h [SbL Cl ] Cl + SbCl
3
(VI)
The [ν(Sb-S) and ν(Sb-Br)] stretching vibrations are also
3
2
4
2
1
4
Raman active. Thus, the Raman spectrum of the ionic salt
Crystal and Molecular Structures of {[SbBr
2
(MBZIM)
Br] H } (4), {[SbBr (µ
Br)(EtMBZIM) -S-tHPMT)(tHP-
MT)] } (6), {[SbBr } (7), {[SbBr (µ
5 2 2
Br)(MTZD) } (8), and {[SbBr ] [(PMTH ) ]} (10).
4
]+
2
-
3
, with O
h
geometry, shows vibrational bands at 259 and
-
[
2
O} (3), {[SbBr
MeOH} (5), {[SbBr
(µ -Br)(PYT)
2
(µ
2
-Br)(MMBZIM)
2
]
2
2
-1
198 cm , which are assigned to the v(Sb-Br) and v(Sb-S),
1
4
2 2
]
3 2
(µ
respectively. Dimeric 4 and 5 with one bridging and one
terminal bromine atom exhibit ν(Sb-Br(terminal)) bands at 241
cm (4) and 256 (5) cm and ν(Sb-Br(bridging)) bands at
n
2
2
2
]
n
2
2
-
2
-
+
]
2 n
-
1
-1
-1
14
Crystal structures of antimony(III) bromide compounds are
very rare in the literature (see Introduction). Until now
antimony(III) bromide complexes with thione/thiole were
2
16 (5) cm , whereas the ν(Sb-S) bands appear at 194
14
-1
(
4) and 184 (5) cm . No ν(Sb-Br(bridging)) band was
observed in the case of 4. Polymeric 6 with µ -S displays
2
8
a
found to adopt octahedral (O
h
)
and pseudotrigonal-bipy-
8
b-d
ramidal (Ψ-TBP)
geometries (Scheme 1).
(
12) (a) Daga, V.; Hadjikakou, S. K.; Hadjiliadis, N.; Kubicki, M.; dos
Santos, J. H. Z.; Butler, I. S. Eur. J. Inorg. Chem. 2002, 1718, 1728.
b) Zachariadis, P. C.; Hadjikakou, S. K.; Hadjiliadis, N.; Michaelidis,
A.; Skoulika, S.; Balzarini, J.; De Clercq, S. Eur. J. Inorg. Chem.
004, 1420, 1426. (c) Hadjikakou, S.; Antoniadis, C. D.; Hadjiliadis,
N.; Kubicki, M.; Binolis, J.; Karkabounas, S. Inorg. Chim. Acta 2005,
58, 2861–2866.
ORTEP diagrams of 3, 4, 5, 6, 7, 8, and 10 are shown in
Figures 1-7, whereas selected bond lengths and angles are
given in Table 1.
3, synthesized in methanol/dichloromethane (1:1) solu-
tions, is a monomeric ionic salt in the solid state and it is
(
2
3
(
(
13) Williams, J. D.; Viehbeck, A. Inorg. Chem. 1979, 18, 1823–1825.
14) (a) Ludwig, C.; Dolny, M.; Gotze, H.-J. Spectrochim. Acta, Part A
2
000, 56, 547–555. (b) Lu, S. F.; Huang, J. Q.; Huang, X. Y.; Wu,
(15) La Manna, G.; Turco Liveri, M. L.; Liveri, V. T.; Saiano, F.; Alonzo,
Q. J.; Yu, R. M. Inorg. Chem. 1999, 38, 3801–3805.
G. J. Solution Chem. 1993, 22, 1063–1071.
2236 Inorganic Chemistry, Vol. 48, No. 5, 2009

New Antimony(III) Bromide Complexes
b,c,d-Br arrangement, whereas µ
and 3.069 Å) complete the Ψ-O
D polymer 7 with helical conformation. Finally, the
2
-Br· · · Sb conducts (3.417
h
geometry leading to the
1
equatorial plane in the SP unit of the polymeric 8 is formed
by two S and two Br atoms in a cis-S, cis-Br arrangement,
2
whereas a weaker µ -Br· · · Sb contact (3.742 Å) completes
the Ψ-O geometry leading to the 1D zigzag polymer 8.
h
It is therefore clear that the arrangements around the metal
center of these antimony(III)-thione complexes are octa-
hedral (O
h h
) or pseudo-octahedral (Ψ-O ). In methanolic or
water solutions on the other hand, MBZIM forms the ionic
+
-
salt 3 ({[SbBr
2
(MBZIM)
4
] [Br] H
2
O}) with O
h
geometry
+
most probably through the [SbBr
2
] species.
The complexes of the other thioamide ligands studied here
include dimers (4 and 5) or polymers (6, 7, and 8) with
monomeric units of square pyramidal (SP) geometries around
the metal center as building blocks. Strong intramolecular
interactions between µ
Sb atoms lead to dimeric (4 and 5) or to polymeric (6, 7 and
) assemblies with pseudooctahedral (Ψ-O ) geometries
around the Sb(III) ion. Thus, trans-S, trans-Br SP units lead
to dimers (4 and 5) with two µ -Br interactions. cis-S and
2
-Br (4, 5, 7, and 8) or µ
2
-S (6) and
8
h
Figure 1. Anisotropic ellipsoid representation of 3. The ellipsoids are drawn
at 50% probability level. The unlabeled part of the molecule is generated
by the symmetry operation 1 - x, -y, -z.
2
cis-Br SP stereoisomers lead to zigzag polymeric assemblies
the first example of an ionic antimony(III) bromide com-
of {[SbBr (µ -Br)(MTZD) ] } building blocks through µ -
Br interactions (8). Complexes of b,c,d-Br SP units are
2
2
2 n
2
h
pound with octahedral (O ) geometry. Four sulfur atoms from
thione ligands and two bromide ions form an octahedral (O
h
)
polymers with either zigzag (6) through µ -S bridges or
2
+
cationic [SbS
4 2
Br ] cation in which the two bromide anions
helical (7) through µ -Br bridges assemblies. The structural
2
occupy axial positions. A third bromide counteranion neu-
differences in the bridging atom (µ -Br or µ -S) observed
2
2
tralizes the whole complex. 3 and the corresponding ones
between 6 and 7-8 might be due to (i) the charge of the
bridging atom or (ii) the electron donor capacity between
µ -Br and µ -S because Sb(III) is known to be an acid of
+
-
with SbCl
CH
3
with MBZIM, {[SbCl
2
(MBZIM)
4
] ·Cl ·2H O·
2
+
-
11
(
3
OH)}, {[SbCl
2
4
(MBZIM) ] ·Cl ·3H
2
3
O·(CH CN)} are
2
2
similar species of a new class of Sb compounds.
and 5 are dimers, whereas 6, 7, and 8 are polymers,
built up from monomeric units with square pyramidal (SP)
geometries around the metal center. Two sulfur atoms from
thioamide ligands and three bromine atoms, bound to Sb
atoms formed the building blocks of the dimers and
intermediate strength preferring intermediate bases as ligands
for complex formation (Computational Study). In case of
7with helical structure, the dihedral Sb-Xbridging · · ·Sb’-X’bridging
angle is -37.48°, whereas in 6 and 8 with zigzag polymeric
structures these angles are -168.69° (6) and -152.96° (8),
respectively (Figures 4 and 6).
4
polymers. Strong intramolecular interactions between µ
4, 5, 7, and 8) or µ -S (6) and Sb atoms lead to dimeric (4
and 5) or to polymeric (6, 7, and 8) assemblies with
pseudooctahedral (Ψ-O ) geometries around the Sb(III) ion.
The equatorial plane in both SP units of the dimeric 4
and 5 is formed by two Br and two S atoms in a trans-S,
2
-Br
The Sb-S bond distances varied from 2.514(3) (7) to
2.8427(7) (8) Å (Table 1) in 3-8 and 10, with the longest
(
2
+
-
found in 8. The Sb-S distances in {[SbCl (MBZIM) ] ·Cl ·
2
-
4
+
h
2H O·(CH OH)}, {[SbCl (MBZIM) ] ·Cl ·3H O·(CH CN)}.
2
3
2
4
2
3
3 2 3 2
a,b,c-Cl [SbCl (MBZIM) ], a,b,d-Cl [SbCl (EtMBZIM) ], a,b,c-
1
1
Cl [SbCl (MTZD) ], and b,c,d-Cl [SbCl (tHPMT) ] varied
3
2
3
2
11
trans-Br arrangement. Two strong intramolecular µ
interactions (3.266 Å (4) and 3.203 Å (5)) complete the Ψ-O
geometry leading to the dimeric 4 and 5. Because the sum
2
-Br· · ·Sb
from 2.482 to 2.849 Å. The Sb-Br bond distances in 3-8
and 10 lie between 2.537(3) (8) and 3.0685(14) (7) Å (Table
1). The Sb-Br bond lengths are in agreement with the
h
1
6
3
Me
1
of van der Waals radii for Sb-Br bonds is 4.10-4.51 Å,
the µ -Br · · ·Sb interaction can be considered as strong. The
corresponding bond distances found in [Sb(k -Tm )(k -Tm-
Me
Me
8a
2
)Br] (Tm ) hydrotris(methimazolyl)borate) 2.9163(5) Å,
[SbBr(dmit)(THF)] (dmit ) 2-thioxo-1,3-dithiole-4,5-dithi-
8c
equatorial plane in the SP unit of the polymeric 6 is formed
by three Br and one S atom in b,c,d-Br arrangement. An
n
8
b
olato) 2.5833(3) Å, {[Ph-CHdCH(Ph)S]SbBr} 2.505(1) Å,
8d
2
additional strong intramolecular µ -S· · ·Sb interaction (3.221
6 4 2
and [S(C H S) ]SbBr 2.6373(6) Å.
Å shorter than the sum of van der Waals radii (4.0-4.47
Å) ) completes the Ψ-O geometry forming a 1D zigzag
h
polymeric 6. The equatorial plane in the SP unit of the
polymeric 7 is formed by three Br and one S atoms in a
The C-S bond lengths in the case of 3-8 and 10 varied
from 1.676(18) to 1.761(3) Å, supporting the ligand coor-
dination througth their thionate forms (average C-S ) 1.69
1
6
1
1
Å).
Although the axial Br-Sb-Br and the basal S1-Sb-S1a
and S2-Sb-S2a angles are 180°, the corresponding basal
S1-Sb-S2 and S1a-Sb-S2a angles are different that 90°,
(
16) (a) Batsanov, S. S. Inorg. Mater. 2001, 37, 871–885. Translated from
Neorganicheskie Materialy, 2001, 37, 1031-1046. (b) Bondi, A. J.
Phys. Chem. 1964, 68, 421–451.
Inorganic Chemistry, Vol. 48, No. 5, 2009 2237

Ozturk et al.
Figure 2. (A) Anisotropic ellipsoid representation of the building block of 4 with trans-Br, trans-S SP conformation. The ellipsoids are drawn at 50%
probability level. The counteranion is omitted for clarity (Experimental Section). (B) Strong intramolecular µ
Ψ-O geometry around Sb center. Symmetry codes: (i) x, y, z; (ii) 2 - x, -y, -z.
2
-Br· · ·Sb interactions lead to dimerization with
h
Figure 3. (A) Anisotropic ellipsoid representation of the building block of 5 with trans-Br, trans-S SP conformation. The ellipsoids are drawn at 50%
probability level. (B) Strong intramolecular µ
z; (ii) -x, -y, 1 - z.
2 h
-Br· · ·Sb interactions lead to dimerization with Ψ-O geometry around Sb center. Symmetry codes: (i) x, y,
and therefore the geometry is a distorted octahedron. The
of 180° or 90° (Table 1) as expected from the valance shell
electron pair repulsion theory (VSEPR) (Br1-Sb1-S1 )
88.28(13)° and Br2-Sb1-Br1 ) 172.8(1)° in 4 (Figure 2),
Br2-Sb1-S5 ) 82.49(3)° and Br2-Sb1-Br3 ) 177.76(2)°
lone pair of electrons located on the Sb atom in 4-8 affects
1
7,18
the ideal SP geometries around the metal ion
because
the basal bond angles are found to vary from the ideal values
2238 Inorganic Chemistry, Vol. 48, No. 5, 2009

New Antimony(III) Bromide Complexes
diffraction pattern (A), before and after heating at 110 °C
for 2 h (B and C), and the one after rehydration (D) (Figure
8
). The XRPD diagrams showed that removing a water
molecule from the initial sample (B) led to the crystal lattice
C). These produce (D) following rehydration of (C),
(
identical to the initial (B). The lattice (C) may correspond
to an SP geometry as in the case of chloride analogs of the
1
1
same complexes, whereas (B) and (D) adopt an O
geometry. Finally, a similar behavior was also observed by
h
1
9
Giolando et al. with O
2
influencing the geometry of the
] } complex in a similar fashion.
Computational Study. To investigate further the factors
governing the geometry of antimony(III) thione complexes
crystal structures) we performed computational studies by
V
-
{
2 6 4 3
[Sb (1,2-S C H )
(
means of density functional theory (DFT) with Becke3-LYP
method using standard basis sets 6-31G(d) (Table 2).
Thus, in methanolic or water media the ionic salt 3 with
O
h
geometry was formed, in the case of the MBZIM ligand,
+
most probably through the [SbBr
2
] species (eq V).The ∆G
of eq V is -102.1 or -100.3 Kcal/mol in water or methanol,
respectively.
Other thioamide ligands studied here form dimers or
zigzag and helical polymer complexes that are built up from
SP units. In these cases, either µ
2 2
-Br or µ -S bridges were
observed. The partial negative charges on sulfur atoms were
calculated for the thiones used in this work and the results
are shown in Table 2. They are summarized as: (i) The higher
negative charge on the sulfur atom (-0.45 e), lower HOMO
20a
energy, which is related with its basicity (-0.3448 hartree)
and higher nucleophilicity (-0.3556 hartree) forms zigzag
polymeric conformation with µ -S bridges in the case of the
2
tHPMT complex. (ii) Ligands with lower negative charges
Figure 4. (A) Anisotropic ellipsoid representation of the building block
of 6 with b,c,d-Br SP conformation. The ellipsoids are drawn at 50%
20b
probability level. (B) Strong intramolecular µ
2
-S· · ·Sb interactions lead to
zigzag polymerization with Ψ-O
h
geometry around Sb center. Symmetry
1
1
codes: (i) x, y, z; (ii) x, /
2
- y, /
2
+ z; (iii) x, y, 1 + z.
on their sulfur atoms, on the other hand, with lower basicity
and lower nucleophilicity yield polymers with µ
Thus, the PYT and MTZD ligands with lower sulfur charge
2
-Br bridges.
in5(Figure3),Br1-Sb1-Br3)92.97(1)°andBr1-Sb1-Br2
165.33(1)° in 6 (Figure 4), Br1-Sb1-Br2 ) 165.39(5)°
and Br1-Sb1-S12 ) 79.54(10)° in 7 (Figure 5) and
Br3-Sb1-S2 ) 170.35(2)° and Br2-Sb1-S2 ) 88.74(2)°
in 8 (Figure 6).
)
(
(
-0.38 e (PYT) and -0.31 e (MTZD)), lower basicity
-0.2028 and -0.2162 hartree for PYT and MTZD, respec-
tively), and lower nucleophilicities (-0.1470 hartree (PYT)
and -0.1853 hartree (MTZD)) (Table 2)) afford polymeric
complexes with helical (7) and zizag (8) conformations
1
0 is a polymeric ionic salt compound in the solid state,
and it is the first example of a new category of antimony(III)
2
-
2
through µ -Br bridges. (iii) Ligands with similar negative
compounds. Five bromide ions form a dianionic [SbBr
counterion with SP geometry around Sb(III) Sb-Br bond
distance varied between 2.57-2.26 Å. One bridging µ -Br
unit complete the octahe-
dron around the metal center. The (Sb-(µ -Br) is found to
5
]
charges on their sulfur atoms and lower bacicity and
nucleophilicity form dimers. Thus, sulfur charges of -0.37
e in case of MMBZIM ligand and -0.38 e for EtMBZIM
and more lower HOMO energies (basicity) (-0.1994 and
2
2
-
5
atom from a sequential [SbBr ]
2
-
0.1928 hartree for MMBZIM and EtMBZIM) and nulceo-
be 3.194 Å, whereas the basal angles are almost 90° (Table
philicities of -0.1725 and -0.1694 hartree for MMBZIM
1
) confirming the octahedral arrangement. The compound
and EtMBZIM respectively (Table 2) lead to dimers with
µ -Br bridges (4 and 5). This result may be attributed to steric
2
reasons in case of the trans isomers where the formation of
dimers allowed by their general arrangements stops the
reaction and polymers cannot form for 1, 2, and 9 where
structural data are not available yet; the computational studies
indicate polymeric assemblies for 1 and 2 most probably with
+
is neutralized by two protonated PMTH
2
ligands.
X-ray Powder Diffraction Study. To examine further our
hypothesis about the influence of water or methanol on the
geometry adopted by the Sb(III) complexes (conductivity
measurements) we studied the X-ray powder diffraction
(
XRPD) spectra of 3 (calculated from single crystal X-ray
µ
2
-S bridges and a dimeric conformation with the µ
2
-Br
(
(
17) (a) Haiduc, I.; Silvestru, C. Main Group Elements and Their
Compounds; Springer-Verlag: Berlin, 1996; p 355. (b) Liu, Y; Tiekink,
E. R. T. CrystEngComm 2005, 7, 20–27.
18) Vickaryous, W. J.; Zakharov, L. N.; Johnson, D. W. Main Group Met.
Chem. 2006, 5, 51–59.
bridge in the case of 9 (Table 2).
(19) Wegener, J.; Kirschbaum, K; Giolando, D. M. J. Chem. Soc., Dalton
Trans. 1994, 121, 3–1218.
Inorganic Chemistry, Vol. 48, No. 5, 2009 2239

Ozturk et al.
Figure 5. (A) Anisotropic ellipsoid representation of the building block of 7 with b,c,d-Br SP conformation. The ellipsoids are drawn at 50% probability
level. The strange shape of Br3 ellipsoid is probably the result of the disorder (text). (B) Strong intramolecular µ -Br· · ·Sb interactions lead to helicoidal
2
1
5
1
1
polymerization with Ψ-O
h
geometry around Sb center. Symmetry codes: (i) x, y, z; (ii) 2 - x, y, /
2
- z; (iii) /
2
- x, -y, z; (iv) /
2
+ x, -y, / - z.
2
Biological Tests. Cytostatic Activity. 1-10 were evalu-
ated in vitro for their inhibitory effects on the proliferation
of murine leukemia cells (L1210), murine mammary
carcinoma cells (FM3A), human T-lymphocyte cells
Sb 1-10 toward lung embryonic fibroblasts (Hel) cells
and their concentrations required to cause visible alter-
ations in 50% of intact Hel cells are also reported in Table
3. Complexes 1-10 showed usually a modest cytostatic
activity against the tumor cell lines studied (Table 3).
Antimony(III) bromide-thione complexes consistently
showed a more selective antiproliferative activity against
HeLa cells, which also observed in case of the corre-
(
(
Molt4/C8, CEM) and human cervix carcinoma cells
HeLa). The results of this study are reported, as 50%
inhibitory concentration (IC50) values in Table 3. The
corresponding IC50 values of the cytotoxic activity of the
2240 Inorganic Chemistry, Vol. 48, No. 5, 2009

New Antimony(III) Bromide Complexes
Figure 6. (A) Anisotropic ellipsoid representation of the building block of 8 with cis-Br, cis-S SP conformation. The ellipsoids are drawn at 50% probability
level. (B) Strong intramolecular µ
2
-Br· · ·Sb interactions lead to zigzag polymerization with Ψ-O
h
geometry around the Sb center. Symmetry codes: (i) x, y,
1
1
z; (ii) x, /
2
- y, /
2
+ z; (iii) x, y, 1 + z.
sponding antimony(III) chloride complexes studied previ-
respectively, indicating low cytotoxic activity of 1-10
against these cell lines in respect to cisplatin.
1
1
ously (Table 3). However, the antimony(III) bromide
complexes studied here were at the average less active
than the corresponding chlorides studied previously (Table
Conclusions
1
1
3
). The antiproliferative activity against cervix carci-
The conclusions drawn from the above work are: (i) the
geometries around antimony(III) are found to be either
noma (HeLa) cells was 2-3 to >10-fold more potent than
against the leukemia and lymphocyte cells. Polymeric
ionic 10 with O geometry around the metal center exhibits
h
octahedral (O
h
h h
) or pseudo-octahedral (Ψ-O ). Thus, the O
geometry in case of the ionic salt 3 is achieved, most
a slightly stronger cytotoxicity against murine leukemia
cells (L1210), murine mammary carcinoma cells (FM3A),
T-lymphocyte cells (Molt4/C8, CEM), and human cervix
carcinoma cells (HeLa). The corresponding IC50 values
found for cisplatin and carboplatin on the proliferation of
HeLa cells are 10 and >37 µM (3.0 and >11 µg/ml),
probably through ionization, as shown in eqs V and VI,
+
producing the [SbBr
2
] species. This assembly is found to
1
1
depend solely on solvent media. The other thioamide
ligands studied here produce dimers (4 and 5) or polymers
2
0a
(21) (a) Carland, M.; Tan, K. J.; White, J. M.; Stephenson, J.; Murray, V.;
Denny, W. A.; McFadyen, D. J. Inorg. Biochem. 2005, 99, 1738–
1743. (b) Shamsuddin, S.; Takahashi, I.; Siddik, Z. H.; Khokhar, A. R.
J. Inorg. Biochem. 1996, 61, 291–301. (c) Dabholkar, M.; Parker, R.;
Reed, E. Mutat. Res. 1992, 274, 45–56.
respectively.
Thus, all antimony(III) 1-10 tested
showed comparable activity against the cervix carcinoma
HeLa cells, whereas the cytotoxicity of 10 is 3-4 times
2
0a
higher than that of carboplatin. The IC50 values found
for cisplatin on the proliferation of L1210 or Molt4 cells
(
22) (a) Oxford Diffraction, CRYSALIS CCD and CRYSALIS RED, version
p171.29.2; Oxford Diffraction Ltd.: Abingdon, Oxford, England, 2006.
(b) CrysAlis CCD, version 1.171.31.5; Oxford Diffraction Ltd. (release
2
0b,22b
are 0.23 and 0.33 µM (0.07 and 0.1 µg/ml),
28-08-2006 CrysAlis171.NET). (c) CrysAlis RED, version 1.171.31.5;
Oxford Diffraction Ltd. (release 28-08-2006 CrysAlis171.NET). (d)
Sheldrick, G. M. Acta Crystallogr. 1990, A46, 467. (e) Sheldrick, G. M.
SHELXL-97, Program for the Refinement of Crystal Structures,
University of G o¨ ttingen: G o¨ ttingen, Germany, 1997.
(
20) (a) I. Fleming, Frontier Orbitals and Organic Reactions; Wiley: Londo,
976; 183-190, pp 35-40. (b) Hemmateenejad, B.; Safarpour, M. A.;
Taghavi, F. J. Mol. Struct. (Theochem) 2003, 635.
1
Inorganic Chemistry, Vol. 48, No. 5, 2009 2241

Ozturk et al.
Figure 8. X-ray powder diffraction (XRPD) diagrams of 3 (calculated from
single crystal X-ray diffraction pattern A) before and after heating at 110
°
C for 2 h (B and C) and the one after rehydration (D).
relative basicity between µ
2 2
-Br and µ -S because Sb(III) in
terms of Pearson’s hard and soft acid and base approach is
known to be an intermediate acid preferring to be bound to
intermediate bases as ligands in forming complexes.
The complexes showed moderate cytostatic activity against
several tumor cell lines with preference for human cervix
carcinoma (HeLa) cells as also observed in case of the
Figure 7. (A) Anisotropic ellipsoid representation of the building block
of 10. The ellipsoids are drawn at 50% probability level. The unlabeled
part of the molecule is generated by the symmetry operation -x, -y, 1 -
z. (B) Strong intramolecular µ -Br· · ·Sb interactions lead to 1D polymer-
2
ization with Ψ-O
two disordered µ
h
geometry around Sb center. For clarity, only one of the
-Br atoms (with 0.5 occupancy) is shown. Symmetry
codes: (i) x, y, z; (ii) 1 + x, y, z; (iii) -1 + x, y, z.
1
1
2
corresponding antimony chloride complexes.
Experimental Section
(
6, 7, and 8), containing SP building blocks. In these cases,
either µ -Br or µ -S bridges were observed. Strong intramo-
lecular interactions between µ -Br (4, 5, 7, and 8) or µ -S
6) and Sb atoms lead to dimeric (4 and 5) or polymeric (6,
Materials and Instruments. All solvents used were of reagent
grade. Antimony(III) bromide (Aldrich) as well as thiones thiourea
2
2
2
2
(
Aldrich), 2-mercapto-1-methylimidazole (Sigma), 2-mercaptoben-
zimidazole (Merck), 2-mercapto-5-methylbenzimodazole (Aldrich),
-ethoxy-2-mercapto benzimidazole (Aldrich), 2-mercapto-3,4,5,6-
(
7
h
, and 8) assemblies with pseudooctahedral (Ψ-O ) geom-
5
etries around the Sb(III) ion. Thus, trans-S, trans-Br, and
SP units lead to dimers (4 and 5) through two µ -Br
interactions. cis-S, cis-Br, and SP stereoisomers lead to
zigzag polymeric assemblies through µ -Br interactions (8).
Complexes of b,c,d-Br SP units built up polymers with either
zigzag (6) (through µ -S bridges) or helical (7) (through µ
Br bridges) assemblies. Crystallographic and computational
data suggest that the differences in the bridging atoms (µ
Br or µ -S) observed between 6 and 7-8 might be due to
i) the charge of the bridging atom with the higher negatively
charged atom (Br or S) to bridge the Sb units and (ii) the
tetrahydro-pyrimidine (Aldrich), 2-mercaptopyridine (Fluka), 2-mer-
captothiazolidine (Aldrich), 3-methyl-2-benzothiazolinthion (Ald-
rich), and 2-mercaptopyrimidine (Aldrich) were used without further
purification. Elemental analyses for C, H, N, and S were carried
out with a Carlo Erba EA MODEL 1108 elemental analyzer.
Melting points were measured in open tubes with a STUART
scientific apparatus and are uncorrected. Infrared spectra in the
2
2
2
2
-
-1
region of 4000-370 cm were obtained for KBr pellets, whereas
far-infrared spectra in the region of 400-50 cm- were measured
for polyethylene discs, with a PerkinElmer Spectrum GX FTIR
spectrometer. Micro Raman spectra (64 scans) were recorded at
room temperature using a low-power (∼30 mW) green (514.5) mm
laser on a Renishaw In Via spectrometer set at 2.0 resolution.
Thermal studies were carried out on a Shimadzu DTG-60 simul-
2
-
1
2
(
(
23) (a) Becke, A. D. Phys. ReV. A 1988, 38, 3098–3100. (b) Becke, A. D.
J. Chem. Phys. 1993, 98, 5648–5652. (c) Lee, C.; Yang, W.; Parr,
R. G. Phys. ReV. B 1988, 37, 785–789. (d) Stephens, P. J.; Devlin, F,
J; Chabalowski, C. F.; Frisch, M. J. J. Phys. Chem. 1994, 98, 1162311
3
-1
taneous DTA-TG apparatus, under a N2 flow (50 cm min ) at a
-1
heating rate of 10 °C min . Conductivity titrations were performed
627. (e) Hehre, W. J.; Ditchfield, R; Pople, J. A. J. Chem. Phys. 1972,
out at T ) 293 K in methanol and acetonitrile or acetonitrile/water
5
6, 2257–2261. (f) Frisch, M. J.; Pople, J A; Binkley, J. S. J. Chem.
Phys. 1984, 80, 3265–3269. (g) Frisch, M. J.; Trucks, G. W.; Schlegel,
H. B.; Scuseria, G. E.; Robb, M. A.; Cheeseman, J. R.; Zakrzewski,
V. G.; Montgomery, J. A., Jr.; Stratmann, R. E.; Burant, J. C.;
Dapprich, S.; Millam, J. M.; Daniels, A. D.; Kudin, K. N.; Strain,
M. C.; Farkas, O.; Tomasi, J.; Barone, V.; Cossi, M.; Cammi, R.;
Mennucci, B.; Pomelli, C.; Adamo, C.; Clifford, S.; Ochterski, J.;
Petersson, G. A.; Ayala, P. Y.; Cui, Q.; Morokuma, K.; Malick, D. K.;
Rabuck, A. D.; Raghavachari, K.; Foresman, J. B.; Cioslowski, J.;
Ortiz, J. V.; Stefanov, B. B.; Liu, G.; Liashenko, A.; Piskorz, P.;
Komaromi, I.; Gomperts, R.; Martin, R. L.; Fox, D. J.; Keith, T.; Al-
Laham, M. A.; Peng, C. Y.; Nanayakkara, A.; Gonzalez, C.; Challa-
combe, M.; Gill, P. M. W.; Johnson, B.; Chen, W.; Wong, M. W.;
Andreas, J. L.; Gonzalez, C.; Head-Gordon, M.; Replogle, E. S.; Pople,
J. A. Gaussian 98; Gaussian: Pittsburgh, PA, 1998.
solutions with a WTF LF-91 conductivity meter.
Synthesis and Crystallization of [SbBr
3
(TU)
O} (3), {[Sb-
2
]
(1),
+
-
[
SbBr
Br (µ
MeOH} (5), {[SbBr
Br)(PYT) (7), {[SbBr
MMBZT) ] (9), and [SbBr
3
(MMI)
-Br)(MMBZIM)
(µ
2
] (2), {[SbBr
} (4), {[SbBr
-S-tHPMT)(tHPMT)]
(µ -Br)(MTZD)
2
(MBZIM)
4
] [Br] H
(µ -Br)(EtMBZIM)
} (6), {[SbBr (µ
(8), [SbBr
2
2
2
2
]
2
2
2
2
]
2
3
2
n
2
2
-
2
]
n
}
2
2
2
]
n
}
3
-
(
2
3
(PMT)] (10). 2-mercapto-benzimi-
dazole (0.5 mmol, 0.075 g), 1.0 mmol of thiourea (0.076 g), 1.0
mmol of 2-mercapto-1-methylimidazole (0.114 g), 1.0 mmol of
2-mercapto-5-methylbenzimidazole (0.164 g), 1.0 mmol of 5-ethoxy-
2-mercaptobenzimidazole (0,194 g), 1.0 mmol of 2-mercapto-
2242 Inorganic Chemistry, Vol. 48, No. 5, 2009

New Antimony(III) Bromide Complexes
3
,4,5,6-tetrahydro-pyrimidine (0.116 g), 1.0 mmol of 2-mercapto-
pyridine (0.111 g), 1.0 mmol of 2-mercaptothiazoline (0.119 g),
.0 mmol of 3-methyl-2-benzothiazolinthione (0.181 g), and 1.0
1
mmol of 2-mercaptopyrimidine (0.112 g) were dissolved in
3
dichloromethane (10 cm ) in the cases of preparation of 2, 3, 4, 6,
3
8
9
and in acetonitrile (10 cm ) in the cases of preparation of 1, 5, 7,
, 10. A solution of antimony(III) bromide (0.181 g, 0.5 mmol) in
methanol (10 cm ) for 1, 3, 5, 7, 9, 10 and in dichloromethane (10
cm ) for 2, 4, 6, 8 was then added to the above solution. The solution
3
3
of 1, 3, 5, 7, 9, and 10 were filtered off, and the resulting clear
solutions were kept in darkness at room temperature to give crystals
of the named 3, 5, 7, 9, and 10 except for 1, which precipitated as
a powder. In the cases of 2, 4, 6 and 8, the solutions were stirred
for 15 min and the resulting precipitations were filtered off and
3
dried. Recrystallization of these solids from hot CH
3
CN (20 cm )
yielded crystals of 4, 6, and 8, whereas 2 precipitated as a powder.
All of the solid products are stable when kept in darkness at room
temperature.
1
: yellow powder; yield, 68%. Elemental analysis, Found: C,
.39; H, 1.52; N, 10.62; S, 12.13. Anal. Calcd for C Br Sb:
C, 4.68; H, 1.57; N, 10.91; S, 12.48. IR (cm ): 3370m, 3282m,
4
2
H
8
3 4 2
N S
-1
3
201m, 2361m, 1634s, 1405m, 1120w, 688m, 608m, 548m.
: yellow powder; yield, 65%. Elemental analysis, Found: C,
6.69; H, 1.90; N, 9.88; S, 10.39. Anal. Calcd for C Sb:
2
1
8 3 4 2
H12Br N S
-1
C, 16.20; H, 2.05; N, 9.50; S, 10.87. IR (cm ): 3092s, 3000w,
2
1
938w, 2884w, 1623w, 1570s, 1464s, 1350w, 1280m, 1154m,
094m, 1017w, 917w, 738m, 669m, 511w.
3
: orange crystals; yield, 40%. Elemental analysis, Found: C,
3
4.99; H, 2.37; N, 11.31; S, 12.80. Anal. Calcd for
C
28
H
26Br
3
N
8
OS
4
Sb: C, 34.96; H, 3.03; N, 11.25; S, 12.87. IR
-
1
(
cm ): 3069m, 1617m, 1491s, 1450s, 1389w, 1365w, 1347s,
1
254w, 1220w, 1165m, 1007m, 973m, 751s, 618w, 599s, 468w.
: yellow crystals; yield, 65%. Elemental analyses, Found: C,
8.01; H, 2.11; N, 8.01; S, 9.55. Anal. Calcd for C16 Sb:
4
2
H
3 4 2
16Br N S
-1
C, 27.85; H, 2.34; N, 8.12; S, 9.30. IR (cm ): 3129m, 1616m,
1
448s, 1326m, 1184m, 803s, 719w, 626w, 538w.
: brown crystals; yield, 65%. Elemental analyses, Found: C,
9.39; H, 2.56; N, 7.02; S, 8.32. Anal. Calcd for
5
2
C
-1
18 3 4 3 2
H22Br N O S Sb: C, 29.18; H, 3.09; N, 7.16; S, 8.20. IR (cm ):
3
1
059s, 2973m, 1636s, 1500s, 1461s, 1384s, 1332m, 1258m, 1167s,
117m, 1040m, 962w, 805m, 775w, 670w, 629w, 584m, 517w.
6
: yellow crystals; yield, 69%. Elemental analyses, Found: C,
1
6.68; H, 2.82; N, 9.76; S, 10.99. Anal. Calcd for C Sb:
8 3 4 2
H16Br N S
-1
C, 16.18; H, 2.72; N, 9.43; S, 10.80. IR (cm ): 3328w, 3221m,
2
1
971m, 1623s, 1590m, 1556s, 1438m, 1366m, 1317m, 1219m,
072w, 812m, 688m, 623w, 560m, 412m.
7
: orange crystals; yield, 54%. Elemental analyses, Found: C,
2
0.24; H, 1.69; N, 4.67; S, 10.63. Anal. Calcd for C10 Sb:
3 2 2
H10Br N S
-1
C, 20.57; H, 1.73; N, 4.80; S, 10.99. IR (cm ): 3429m, 2910w,
1
582s, 1511m, 1439w, 1368w, 1261m, 1127m, 761s, 485m.
: yellow crystals; yield, 75%. Elemental analyses, Found: C,
2.22; H, 1.46; N, 4.23; S, 21.02. Anal. Calcd for C Sb:
8
1
6 3 2 4
H10Br N S
-1
C, 12.01; H, 1.68; N, 4.67; S, 21.38. IR (cm ): 3449w, 3263s,
2
362m, 1514s, 1339w, 1302m, 1042m, 991w, 926w, 614w, 425w.
: yellow crystals; yield, 54%. Elemental analyses, Found: C,
6.27; H, 1.91; N, 10.61; S, 12.12. Anal. Calcd for
9
2
C
-1
16 3 2 4
H14Br N S Sb: C, 26.54; H, 1.95; N, 10.91; S, 12.48. IR (cm ):
3
1
446m, 2361m, 1459s, 1426m, 1348s, 1313m, 1262m, 1141m,
096s, 967s, 752s, 638w, 522m, 423w.
1
0: orange crystals; yield, 30%. Elemental analyses, Found: C,
1
2.68; H, 1.38; N, 7.55; S, 9.07. Anal. Calcd for C Sb:
8 5 4 2
H10Br N S
Inorganic Chemistry, Vol. 48, No. 5, 2009 2243

Ozturk et al.
Table 2. Gas and Dichloromethane Phase B3LYP/6-31G(d) Calculated Energy, Charge for S Atoms, HOMO, LUMO and Nucleophilicity (n), Values
of Ligands
Gas Phase
HOMO
Dichloromethane Phase
HOMO LUMO
(Hartrees) charge(S) (e) (Hartrees) (Hartrees)
energy
LUMO
nucleophlicitya
(Hartrees) charge(S) (e) (Hartrees) (Hartrees) (Hartrees)
energy
nucleophlicity
(Hartrees)
a
ligands
TU
MMI
MBZIM
MMBZIM -817.3947
EtMBZIM -931.9172
-548.2156
-664.9445
-778.0771
-0.30
-0.32
-0.30
-0.30
-0.31
-0.36
-0.31
-0.23
-0.22
-0.25
-0.4079 -0.0069
-0.2002 0.0036
-0.4011
-0.2038
-0.3152
-0.1683
-0.1657
-0.3644
-0.1433
-0.1807
-0.1652
-0.1325
-548.2299
-664.9597
-778.0907
-817.4082
-931.9363
-664.9684
-646.4914
-968.4777
-1160.2246
-662.5252
-0.41
-0.40
-0.37
-0.37
-0.38
-0.45
-0.38
-0.31
-0.28
-0.34
-0.4064
-0.2055
0.0124
0.0051
-0.4189
-0.2106
-0.3150
-0.1725
-0.1694
-0.3556
-0.1470
-0.1853
-0.1665
-0.1400
-0.3457 -0.0305
-0.1980 -0.0297
-0.1911 -0.0254
-0.3421 -0.0272
-0.1994 -0.0269
-0.1928 -0.0234
tHPMD
PYT
MTZD
MMBZT
PMT
-664.9506
-646.4803
-968.4629
-1160.2149
-662.5103
-0.3536
0.0107
-0.3448
0.0107
-0.2011 -0.0578
-0.2135 -0.0328
-0.2109 -0.0456
-0.2076 -0.0751
-0.2028 -0.0559
-0.2162 -0.0309
-0.2136 -0.0471
-0.2126 -0.0726
a
n ) EHOMO - ELUMO
.
Table 3. Cytostatic Activity of the Compounds Against murine Leukemia Cells (L1210), Murine Mammary Carcinoma Cells (FM3A), Human
T-Lymphocyte (Molt4/C8, CEM) and Human Cervix Carcinoma (HeLa) Cells
c
b
IC50 (µg/ml)
MCC (µg/ml)
Sb(III) bromide compound
(TU) ] (1)
L1210
FM3A
Molt4/C8
CEM
Hela
Hel
Hel
ref
c
c
c
c
c
c
c
c
c
c
[
[
SbBr
SbBr
3
2
20 ( 9
42 ( 14
42 ( 15
24 ( 6
41 ( 11
22 ( 6
19 ( 3
23 ( 8
43 ( 28
15 ( 3
10.8
47 ( 1
72 ( 1
66 ( 1
52 ( 8
64 ( 2
54 ( 4
56 ( 6
53 ( 1
57 ( 8
37 ( 4
32.3
12 ( 2
27 ( 12
21 ( 9
14 ( 2
26 ( 3
16 ( 6
13 ( 3
15 ( 4
15 ( 6
9.4 ( 0.8
21.5
55 ( 21
75 ( 25
67 ( 11
50 ( 7
42 ( 2
63 ( 20
42 ( 16
59 ( 11
31 ( 17
44 ( 25
80.7
12 ( 0
17 ( 2
20 ( 2
14 ( 2
16 ( 0
14 ( 1
3.7 ( 0.5
15 ( 0
16 ( 2
3.1 ( 1.2
5.7
5.6 ( 3.5
22 ( 17
12 ( 1
15 ( 1
<8
12 ( 0
9.3 ( 0.0
12 ( 2
17 ( 12
5.9 ( 1.2
100
500
500
500
g100
500
g20
500
500
20
3
(MMI) ] (2)
2
{
{
{
{
{
{
[SbBr
2
2
2
3
2
2
(MBZIM)
4
]+ [Br]-
H
2
O} (3)
} (4)
MeOH} (5)
[SbBr
[SbBr
[SbBr
[SbBr
[SbBr
(µ
(µ
(µ
(µ
(µ
2
2
2
2
2
-Br)(MMBZIM)
-Br)(EtMBZIM)
2
]
]
2
2
2
-S-tHPMT)(tHPMT)]
-Br)(PYT) } (7)
-Br)(MTZD) } (8)
] (9)
n
} (6)
2 n
)
]
2 n
[
SbBr
3
(MMBZT)
2
2-
+
{
{
{
[
[
[
[
[SbBr
5
]
[(PMTH
2
)
2
]} (10)
+
-
11
11
[SbCl
[SbCl
2
(MBZIM)
(MBZIM)
4
] ·Cl ·2H
4
2
O·(CH
O·(CH
3
OH)}
CN)}
+
-
2
] ·Cl ·3H
2
3
17.3
16.4
12.9
13.5
76.1
54.4
25.3
26.1
25.9
23.8
9.2
14.9
76.1
59.2
14.8
57.8
6.1
4.1
4.3
3.2
1
1
1
1
1
1
1
1
SbCl
3
3
3
3
(MBZIM)
(EtMBZIM)
(MTZD)
(tHPMT)
2
]
SbCl
SbCl
SbCl
2
]
2
]
2
]
13.4
42.4
17.5
54.3
3.5
cisplatin
carboplatin
a
0.07
0.1
3.0
<11
20a, b
20a
a
b
5
0% inhibitory concentration or compound concentration required to inhibit tumor cell proliferation by 50%. Minimal cytotoxic concentration required
c
to cause a microscopically visible alteration of cell morphology. This work.
Table 4. Structure Refinement Details for 3-8 and 10
3
4
5
6
7
8
10
empirical formula
fw
T (K)
C
28
H
26Br
3
N
8
OS
4
Sb
C
16
H
16Br
3
N
4
S
2
Sb
C
19
H
24Br
3
N
4
O
3
S
2
Sb
C
8
H
16Br
3
N
4
S
2
Sb
C
10
H
10Br
3
N
2
S
2
Sb
C
6
H
10Br
3
N
2
S
4
Sb
8 5 4 2
C H10Br N S Sb
Monoclinic
100(2)
996.34
100(2)
689.93
100(2)
782.02
100(2)
593,84
100(2)
583.80
293
599.89
100(2)
cryst syst
space group
a (Å)
b (Å)
c (Å)
Monoclinic
P2 /c
13.806(5)
16.935(7)
7.808(3)
90
98.262(5)
90
1806.6(12)
1
Triclinic
Triclinic
Monoclinic
P2 /c
9.7370(6)
20.7721(10)
8.7033(4)
90
107.507(5)
90
1678.77(16)
4
Orthorhombic
Ccca
10.831(2)
28.157(6)
25.489(5)
90
90
90
7773(3)
8
2.125
8.8
Monoclinic
P2 /c
8.5545(3)
14.8824(4)
12.2796(3)
90
100.417(3)
90
1537.57(8)
4
Monoclinic
P2 /n
1
P1j
P1j
1
1
1
8.8226(13)
9.0708(2)
9.2943(2)
15.3618(4)
78.752(2)
87.505(2)
86.356(2)
1267.02(5)
2
5.7512(1)
15.1339(4)
10.5575(3)
90
104.248(3)
90
890.64(4)
2
2.788
11.2837(17)
12.505(2)
110.002(14)
91.959(13)
102.982(13)
1131.5(3)
2
R (deg)
ꢀ
(deg)
γ (deg)
3
V (Å )
Z
3
F
calcd (g/cm )
µ (mm
1.864
4.4
0.044, 0.077, 0.72
2.013
6.7
1.986
6.0
2.350
9.0
2.592
10.1
-1
)
13
R, wR, S
0.069, 0.203, 1.00 0.033, 0.071, 0.93
0.019, 0.041, 0.96 0.067, 0.207, 1.05 0.019, 0.038, 0.92 0.022, 0.051, 0.97
C, 12.85; H, 1.35; N, 7.49; S, 8.58. IR (cm-1): 3443m, 2895m,
All data were corrected for Lorentz-polarization effects and
22a,c
2
4
361m, 1600s, 1547m, 1377w, 1263m, 1190s, 988m, 773m, 625w,
65m.
absorption.
The structures were solved with direct methods with
22d
SHELXS97 and refined by full-matrix least-squares procedures on
2
22e
X-ray Structure Determination. Intensity data for the colorless
F with SHELXL97. All non-hydrogen atoms were refined aniso-
tropically, and hydrogen atoms were located at calculated positions
and refined via the “riding model” with isotropic thermal parameters
crystals of 3, 4, 5, 6, 8, and 10 were collected on an Oxford
22a
Diffraction CCD instrument, using graphite-monochromated Mo
radiation (λ ) 0.71073 Å), whereas a KUMA KM4CCD four-circle
diffractometer with a CCD detector used for 7, using graphite-
3
fixed at 1.2 (1.3 for CH groups) times the Ueq value of the appropriate
carrier atom. Significant crystal data are given in Table 4.
2
2b
monochromated Mo radiation (λ ) 0.71073 Å). Cell parameters
The crystal structure of 3 could be refined better (with regard
to both the R factors and displacement parameters) if the
2
2c
were determined using up to 9402 reflections.
244 Inorganic Chemistry, Vol. 48, No. 5, 2009
2

New Antimony(III) Bromide Complexes
-
-
counteranion is defined as a disorder Br /OH (53/47). This may
have occurred because of a hydrolysis process that took place
during the preparation. The strange shape of Br3 ellipsoid in
the case of the structure of 7 is probably the result of a disorder.
Supplementary data are available from the CCDC, 12 Union
Road, Cambridge CB2 1EZ, U.K., (e-mail: deposit@ccdc.cam.ac.uk),
on request, quoting the deposition nos. CCDC-702615 (3), 702617
100 µL of a the cell suspensions were added to 100 µL of an
appropriate dilution of the test compounds in 96 well microtiter
plates. After incubation at 37 °C for two (L1210 and FM3A) or
three (Molt4, CEM and HeLa) days, the cell number was determined
using a Coulter counter. The number of the suspension cells could
be counted directly; the number of the monolayer HeLa cells were
counted after detachment of the cells upon trypsinization. The IC50
was defined as the compound concentration required to inhibit cell
proliferation by 50%.
(
4), 702615 (5), 702620 (6), 702619 (8) and 702618 (10),
respectively, and CCDC-704581 for 7.
X-ray Powder Diffraction. X-ray powder diffraction patterns,
from powders derived from the crushed, were obtained using a
Bruker AXS D8 Avance diffractometer in Bragg-Brentano ge-
ometry equipped with a Cu sealed-tube radiation source (λ )
Acknowledgment. This research was carried out in partial
fulfillment of the requirements for the Ph.D. thesis of I.I.O.
within the graduate program in Bioinorganic Chemistry at
the University of Ioannina. S.K.H., N.H., H.S, and I.S.B.
would like to acknowledge a NATO grant for the exchange
of scientists. I.I.O. would like to thank the Hellenic Ministry
of Education for a scholarship for postgraduate studies. The
research of J.B. was supported by grant GOA no. 05/19.
1
2
0
.54178 Å) and a secondary beam graphite monochromator. The
θ range used in the measurements was from 5° to 50° in steps of
.02° with a count time of 10 s per step.
Computational Studies. All of energies were calculated with
2
3a-d
DFT Becke3-LYP method
together with the standard basis
2
3e,f
23g
sets 6-31G(d)
as implemented in the Gaussian 98 program.
The total energies are given in Hartrees using the conversation factor
-
1
1
Hartree ) 627.5095 kcal mol .
Note Added after ASAP Publication. This article was
published ASAP on January 26, 2009, with minor text errors
in equations II and III. The corrected article was published
ASAP on February 2, 2009.
Cytostatic Activity Assays. Murine leukemia L1210, murine
mammary carcinoma FM3A, human T-lymphocyte Molt 4 and
CEM, and human cervix carcinoma HeLa cells were suspended at
3
00 000-500 000 cells/ml in RPMI-1640 culture medium supple-
mented with 10% fetal bovine serum and 2 mM L-glutamine, and
IC8019205
Inorganic Chemistry, Vol. 48, No. 5, 2009 2245