New dimeric and supramolecular organotin(IV) complexes with a tridentate schiff base as potential biocidal agents

Article abstract of DOI:10.1016/j.jorganchem.2011.04.010

The paper describes the synthesis and structural characterization of six new diorganotin(IV) compounds 1-6, [R₂SnL] and a monoorganotin(IV) derivative, C₄H₉SnClL (7). Here L = N′-(5-bromo-2- oxidobenzylidene)-N-(oxidomethy

Full text of DOI:10.1016/j.jorganchem.2011.04.010

Journal of Organometallic Chemistry 696 (2011) 2772e2781
Contents lists available at ScienceDirect
Journal of Organometallic Chemistry
journal homepage: www.elsevier.com/locate/jorganchem
New dimeric and supramolecular organotin(IV) complexes with a tridentate
schiff base as potential biocidal agents
,
b
Shaukat Shujah a, Zia-ur-Rehman a, Niaz Muhammad a, Saqib Ali a , Nasir Khalid ,
*
Muhammad Nawaz Tahir c
a Department of Chemistry, Quaid-i-Azam University, Islamabad 45320, Pakistan
b Chemistry Division, Pakistan Institute of Nuclear Science and Technology, PO Nilore, Islamabad, Pakistan
c University of Sargodha, Department of Physics, Sargodha, Pakistan
a r t i c l e i n f o
a b s t r a c t
Article history:
The paper describes the synthesis and structural characterization of six new diorganotin(IV) compounds
1e6, [R2SnL] and
a
monoorganotin(IV) derivative, C4H9SnClL (7). Here
L
¼
N0-(5-bromo-2-
Received 8 March 2011
Received in revised form
6 April 2011
oxidobenzylidene)-N-(oxidomethylene)hydrazine ligand with ONO tridentate chelation capability and
R ¼ CH3 (1), C2H5 (2), n-C4H9 (3), C6H5 (4), C8H17 (5), tert-C4H9 (6), The packing diagram offers a supra-
molecular structure for 1 and a dimeric structure for 4 with distorted square-pyramidal and distorted
trigonal geometry, respectively. The different geometry of 1 than 4 can be attributed to the presence of
intermolecular non-covalent Sn—O and Sn—H interactions in the former. The antifungal, antibacterial,
antiurease and antileishmanial activities of these complexes proved them to be active biologically and
may be formulated as new metal-based drugs in future.
Accepted 11 April 2011
Keywords:
Organotin(IV) derivatives
ONO schiff base
Dimeric
Supramolecular
Antifungal
Ó 2011 Elsevier B.V. All rights reserved.
Antibacterial
Antileishmanial
Antiurease
1. Introduction
antileishmanial activities. This paper is unique in the sense that the
antiurease and antileishmanial activities for organotin(IV) schiff
Schiff base ligands received instant and enduring popularity not
only they have played a seminal role in the development of modern
coordination chemistry [1], but they can also be found at key points
in the development of inorganic chemistry [2], catalysis [3,4]
medicinal imaging [5], optical materials [6], and thin films [7,8].
The chemistry of organotin(IV) has been the area of interest for
many years because of their industrial and biomedical applications
[9]. Several organotin(IV) complexes have been found as affective
antifouling [10], anti-microbial [11] and antiviral agents. Organo-
tin(IV) complexes with schiff base ligands have been an area of
focus owing to their anti-tumor activities [12e20]. In addition to
this, the complexes belonging to this class also present interesting
structural diversities [21]. Keeping in view all these points and as an
extension of our previous work, we synthesized and characterized
seven new organotin(IV) derivatives of a ONO tridentate schiff base,
N0-(5-bromo-2-oxidobenzylidene)-N-(oxidomethylene)hydrazine,
and carried out their antifungal, antibacterial, antiurease and
bases are scantly available in the literature and the given article
may be the first step in this direction. The profound antileishmanial
activities demand further investigations on these complexes to be
used as antileishmanial agents in future.
2. Experimental
2.1. Chemicals
Organotin(IV) dichlorides, dioctyltin(IV) oxide, butyltin(IV)
chloridedihydroxide, 5-bromo-2-hydroxybenzaldehyde and formic
hydrazide were procured from Aldrich. The organic solvents
(toluene, chloroform, hexane, ethanol etc.) were used of Merck,
Germany and were dried in situ using standard procedures [22] and
freshly collected prior to use.
2.2. Instrumentation
The melting points were determined on an electrothermal
melting point apparatus, model MP-D Mitamura Rieken Kogyo
* Corresponding author. Tel.: þ92 51 90642130; fax: þ92 51 90642241.
E-mail address: drsa54@yahoo.com (S. Ali).
0022-328X/$ e see front matter Ó 2011 Elsevier B.V. All rights reserved.
doi:10.1016/j.jorganchem.2011.04.010

S. Shujah et al. / Journal of Organometallic Chemistry 696 (2011) 2772e2781
2773
(Japan) by using capillary tubes and are uncorrected. The infrared
(IR) spectra were recorded as neat liquids, using NaCl cells or as KBr
pellets for solids on a Bio-Rad Excaliber FT-IR, model FTS 300 MX
2.90; N, 11.53 Found: C, 39.50; H, 2.89; N, 11.57%. IR (cmꢀ1): 1706
(C]O), 3185 (NH),1098 (NeN),1609 (C]N), 3410 (OH)Phenolic.
n
n
n
n
n
spectrophotometer(USA) in the frequency rangeof 4000e400 cmꢀ1
.
2.3.2. Synthesis of Dimethyltin(IV) [N0-(5-bromo-2-oxidobenzylid
ene)-N-(oxidomethylene)hydrazine]; (1)
Multinuclear NMR (1H, 13C, and 119Sn) spectra were recorded on
a Bruker ARX 300 MHz-FT-NMR and a Bruker 400 MHz-FT-NMR
spectrometers Switzerland using CDCl3 as an internal reference.
A 250 mL two-necked flask containing 100 mL toluene, equip-
ped with a reflux condenser was charged with N0-(5-bromo-2-
Chemical shifts (
d
) are given in ppm and coupling constants (J) are
hydroxybenzylidene)formohydrazide 0.73 g (3.0 mmol), and
given in Hz. The multiplicities of signals in 1H NMR are given with
chemical shifts; (s ¼ singlet, d ¼ doublet, t ¼ triplet, q ¼ quartet,
m ¼ multiplet).
triethylamine 0.84 mL (6.0 mmol) along with a magnetic bar. To the
solution of triethylammonium salt of the ligand, dimethytin(IV)
dichloride (0.66 g, 3.0 mmol) in dry toluene was added drop wise
into the flask with stirring at room temperature. The solution
turned yellow, it was stirred for 5 h at room temperature. The white
precipitates of Et3NHCl formed during the reaction were filtered.
The filtrate was concentrated by rotary evaporator to obtain yellow
solid. The product was recrystallized from CHCl3/n-hexane (4:1)
mixture (Scheme 1b).
The mass spectra were recorded on a MAT-311A Finnigan
(Germany). The m/z values were evaluated assuming that H ¼ 1,
C ¼12, N ¼14, O ¼ 16, Cl ¼ 35andSn¼ 120. TheX-raydiffractiondata
were collected on a Bruker SMART APEX CCD diffractometer,
equipped with a 4 K CCD detector set 60.0 mm from the crystal. The
crystals were cooled to 100 ꢁ 1 K using the Bruker KRYOFLEX low-
temperature device and Intensity measurements were performed
IR(cmꢀ1): 1609
n(C]N),1079 n(NeN), 566 n(SneO), 498 n(SneN)
using graphite monochromated Mo-K
a radiation from a sealed
ceramic diffraction tube (SIEMENS). Generator settings were 50 kV/
40 mA. The structure was solved by Patterson methods and exten-
sion of the model was accomplished by direct methods using the
program DIRDIF or SIR2004. Final refinement on F2 carried out by
full-matrix least squares techniques using SHELXL-97, a modified
version of the program PLUTO (preparation of illustrations) and
PLATON package.
2.3.3. Diethyltin(IV) [N0-(5-bromo-2-oxidobenzylidene)-N-(oxidom
ethylene)hydrazine]; (2)
Compound 2 was prepared in the same way as 1, using follo-
wing quantities: N0-(5-bromo-2-hydroxybenzylidene)formohydr-
azide 0.73 g (3.0 mmol), diethyltin(IV) dichloride 0.74 g (3.0 mmol),
triethylamine 0.84 mL (6.0 mmol) were reacted in 1:1:2 ratio. Solid
product was recrystallized in chloroform and n-hexane (4:1)
mixture. IR (cmꢀ1): 1605
(SneN).
n(C]N), 1080 n(NeN), 563 n(SneO), 488
n
2.3. Syntheses
2.3.4. Dibutyltin(IV) [N0-(5-bromo-2-oxidobenzylidene)-N-(ox
idomethylene)hydrazine]; (3)
2.3.1. Synthesis of N0-(5-bromo-2-hydroxybenzylidene)formohydra
zide (H2L)
Compound 3 was prepared in the same way as 1, using
following quantities: N0-(5-bromo-2-hydroxybenzylidene)for-
mohydrazide 0.73 g (3.0 mmol), dibutyltin(IV) dichloride 0.91 g
(3.0 mmol), triethylamine 0.84 mL (6.0 mmol) were reacted in
1:1:2 ratio. Viscous liquid product was obtained. IR (cmꢀ1):
An ethanolic solution of 5-bromo-2-hydroxybenzaldehyde
3.35 g (16.65 mmol) was added slowly to the solution of formic
hydrazide 1.0 g (16.65 mmol), in ethanol with constant stirring at
room temperature. The mixture was refluxed for 1 h and on cooling
yellowcrystalline solid was obtained (Scheme 1a). m.p. 256e258 ꢂC.
Yield 80% (3.236 g). Anal. Calc. for C8H7BrN2O2 (M ¼ 242): C, 39.53; H,
1625
n
(C]N), 1088
n
(NeN), 548 n(SneO), 472 n(SneN).
a
O
H
C
H
H
Br
C
Br
Br
O
N
H
C
N
H
H
N
N
-H2O
H CNHNH2
+
OH
O
1 h reflux
Ethanol
OH
OH
OH
aldo-imine form
imine-ol form
b
H
C
H
C
Br
Br
N
H
N
R
H
N
N
+
R2SnCl2
+
2Et3N
+
2Et3NHCl
OH
O
Sn
OH
O
R
R = CH3(1), C2H5 (2), n-C4H9 (3), C6H5 (4), C8H17 (5), t-C4H9 (6)
c
H
H
Br
Br
C
N
H
C
N
H
N
N
C4H9Sn(OH)2Cl
+
+
2H2O
OH
O
Sn
OH
O
C4H9
Cl
Scheme 1. Synthesis of N0-(5-bromo-2-hydroxybenzylidene)formohydrazide (H2L) (a), diorganotin(IV) derivatives (b) and butylchloridetin(IV) derivative (c).

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S. Shujah et al. / Journal of Organometallic Chemistry 696 (2011) 2772e2781
2.3.5. Diphenyltin(IV) [N0-(5-bromo-2-oxidobenzylidene)-N-(oxido
methylene)hydrazine]; (4)
Compound 4 was prepared in the same way as 1, using follo-
wing quantities: N0-(5-bromo-2-hydroxybenzylidene)formohydr-
azide 0.73
g (3.0 mmol), diphenyltin(IV) dichloride 1.03 g
(3.0 mmol), triethylamine 0.84 mL (6.0 mmol) were reacted in 1:1:2
ratio. Solid product was recrystallized in chloroform and n-hexane
(4:1) mixture. IR (cmꢀ1): 1613
n(C]N), 1073 n(NeN), 570 n(SneO),
469 n(SneN).
2.3.6. Dioctyltin(IV) [N0-(5-bromo-2-oxidobenzylidene)-N-(oxidom
ethylene)hydrazine]; (5)
Compound 5 was prepared in the same way as 1, using follo-
wing quantities: N0-(5-bromo-2-hydroxybenzylidene)formohydr-
azide 0.73 g (3.0 mmol), dioctyltin (IV)oxide 1.09 g (3.0 mmol) were
reacted in 1:1 ratio. Viscous liquid product was obtained. IR (cmꢀ1):
1611 n(C]N), 1082 n(NeN), 569 n(SneO), 460 n(SneN).
2.3.7. Di-tert-butyltin(IV) [N0-(5-bromo-2-oxidobenzylidene)-N-
(oxidomethylene)hydrazine]; (6)
Compound 6 was prepared in the same way as 1, using follo-
wing quantities: N0-(5-bromo-2-hydroxybenzylidene)formohydra-
zide 0.73 g (3.0 mmol), di-tert-butyltin(IV) dichloride 0.91 g
(3.0 mmol), triethylamine 0.84 mL (6.0 mmol) were reacted in 1:1:2
ratio. Solid product was recrystallized in chloroform and n-hexane
(4:1) mixture. IR (cmꢀ1): 1614
465 (SneN).
n(C]N), 1088 n(NeN), 564 n(SneO),
n
2.3.8. Butyltin(IV) [N -(5-bromo-2-oxidobenzylidene)-N-(oxidomet
hylene)hydrazine] chloride; (7)
Compound 7 was prepared in the same way as 1, using follo-
wing quantities: N0-(5-bromo-2-hydroxybenzylidene)formohydr-
azide 0.73 g (3.0 mmol), butyltin(IV) chloridedihydroxide 0.74 g
(3.0 mmol) were reacted in 1:1 ratio. Solid product was recrystal-
lized in chloroform and n-hexane (4:1) mixture (Scheme 1c). IR
(cmꢀ1): 1608
n(C]N), 1080 n(NeN), 560 n(SneO), 468 n(SneN).
3. Results and discussion
3.1. Spectroscopy
In IR spectra of the ligand, the vibration bands due to
OeH and
C ] O were observed at 3185, 3410 and 1706 cmꢀ1
respectively. Due to enolization and deprotonation of the ligand on
complexation with diorganotin moiety, the C ] O band vanished.
The shifting of
C ] N band at 1609 cmꢀ1 to lower energy suggests
nNeH,
n
n
,
n
n
the coordination of azomethine nitrogen to the Sn atom [23]. The
shifting of NeN band from 1098 cmꢀ1 by a value of w20 cmꢀ1 on
complexation can be attributed to the decrease in repulsion of the
lone pairs of electrons on the nitrogen atoms [24]. The presence of
new bands associated with nSneO and nSneN, that were absent in
the precursors, further indicates the formation of complexes [25].
In 1H NMR chemical shift assignments of the diorganotin(IV)
moiety are straightforward from the multiplicity pattern and/or
resonance intensities; whereas the ligand skeleton was assigned by
multiplicity patterns and/or resonance intensities (Table 1). In the
spectra of ligand, single resonance is observed at 5.11 ppm, which is
absent in the spectra of all complexes, indicating the substitution of
phenolic proton by organotin moiety. The coordination of azome-
thine nitrogen with Sn atom shifted the CH]N proton resonance
signal down field by a value of w0.3 ppm with 3J (119Sn, 1H)
coupling constant value in the range 37e48 Hz.
The CSnC angle calculated for compound 1 from 2J (119Sn, 1H)
value, using Lockhart’s equation {
q
¼ 0.0105 [2J]2ꢀ0.799 [2J] þ 122.4},
is 126ꢂ (Table 3) thus, confirming five-coordinate geometry around

S. Shujah et al. / Journal of Organometallic Chemistry 696 (2011) 2772e2781
2775
Table 3
(CeSneC) angles (ꢂ) based on NMR parameters of selected of complexes 1-7.
Comp. No
Compound
1J(119Sn, 13C)
2J(119Sn, 1H)
Angle(ꢂ)
(Hz)
(Hz)
1
2
3
4
5
6
7
Me2SnL
Et2SnL
n-Bu2SnL
Ph2SnL
Oct2SnL
t-Bu2SnL
BuClSnL
646
609
596
639
595
566
615
79
e
e
e
e
e
e
133.4
130.2
134.5
138.5
134.4
131.7
136.3
129.6
e
e
e
e
e
e
Sn atom. The characteristic signals for all the magnetically non-
equivalent alkyl- or phenyl-protons of the organotin moieties have
also been assigned, which are in good agreement with reported
values [26].
The characteristic resonance peaks in 13C NMR spectra of the
complexes were recorded in CDCl3, Table 2. The 13C NMR spectra of
the complexes show a considerable up field shift of all carbon
resonances, compared with the ligand acid. This may be a conse-
quence of an electron density shift from the ligand to the acceptor.
In organotin compounds, the 1J [119Sn, 13C] value is an important
parameter to assess the coordination number of the Sn atom. The
calculated coupling constants for compounds 1-7 were found to be
in the range 566e646 Hz, which described the penta-coordinate
environment about the Sn atom in these compounds [27].
The presence of a single 119Sn peak for complexes 1-7 (Table 2) is
in conformity with the formation of a single species having penta-
coordinated Sn atom [28].
3.2. X-ray structure of H2L
Crystal data and structure refinements of ligand H2L are given in
Table 4. Selected bond angles and distances are listed in Table 5.
Fig. 1 shows the molecular structure along with atomic numbering
Table 4
Crystal data and structure refinement parameters for ligand H2L
Compound No.
H2L
Empirical formula
Formula mass
Crystal system
Space group
a(Å)
C8H7BrN2O2
243.07
Monoclinic
P 21/c
3.827(3)
24.259(2)
9.441(8)
90.00
100.48(4)
90.00
861.9(12)
4
b(Å)
c(Å)
a
b
g
(ꢂ)
(ꢂ)
(ꢂ)
V(Å3)
Z
Crystal habit
size (mm)
Block
0.49 ꢃ 0.43 ꢃ 0.39
r
m
(g.cmꢀ3
)
1.873
(Mo Ka) (mmꢀ1
)
4.73
F(000)
480
Total reflections
2527
Independent reflections
1859
For ðFo ꢄ 4:0
s
ðFoÞÞ
1420
0.033
P
P
RðFÞ ¼ ðjjFoj ꢀ jFcjjÞ= jFoj
For (F0>4.0
s
(F0))
P
P
wRðF2Þ ¼ ½ ½wðFo2 ꢀ Fc2Þ2ꢅ= ½wðFo2Þ2ꢅꢅ1=2
0.053
1.203
2.35e30.10
1859/0/140
ꢀ0.82 and 1.18
Goodness-of-fit
Range (deg)
q
Data/restrictions/params
Largest diff. peak and hole (eÅꢀ3
)

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S. Shujah et al. / Journal of Organometallic Chemistry 696 (2011) 2772e2781
Table 5
Table 6
Selected bond lengths (Å) and bond angles (ꢂ) of ligand H2L .
Hydrogen-bond geometry (Å, ꢂ) for ligand H2Le.
Bond lengths
DꢀH..A
DꢀH
0.81
0.77
H
..A
D
..A
DꢀH..A
136
171
N(1)eC(7)
N(1)eN(2)
N(2)eC(8)
1.275 (6)
1.377 (6)
1.323 (7)
O(1)eC(6)
O(2)eC(8)
Br(1a)eC(3)
1.348 (6)
1.227 (7)
1.896 (5)
O(1)ꢀH(1)..N(1)
1.84
2.10
2.649(3)
2.866(2)
N(2)ꢀH(2)..O(2)
Bond angles
C(2)eC(3)eBr(1a)
C(4)eC(3)eBr(1a)
O(1)eC(6)eC(5)
O(1)eC(6)eC(1)
120.37 (4)
119.34 (4)
117.52 (4)
123.14 (4)
N(1)eC(7)eC(1)
O(2)eC(8)eN(2)
C(7)eN(1)eN(2)
C(8)eN(2)eN(1)
120.95 (4)
123.67 (5)
116.68 (4)
118.33 (4)
group are further away from one another providing enough room
for oxygen atom of the adjacent molecule to interact with Sn atom
(Fig. 3). Thus, the two enolic oxygens are at the apical positions
and the two methyl carbons and azomethinic nitrogen in the
equatorial positions. The SneOshorter (2.106 and 2.086 Å) and SneO
longer bond lengths (2.145 and 2.166 Å) are less than the sum of
van der Waal’s radii of Sn and O (2.8 Å). The OeSneN (equatorial)
and OeSneO (axial) angles also show a large deviation from the
ideal values thus, confirming highly distorted trigonal bipyramidal
geometry. The SneN bond distances of the two molecules are
closer to the sum of covalent radii of Sn and N (2.15 Å) and
significantly less than the sum of van der Waal’s radii (3.75 Å), as
shown in Tables 8 and 9. The packing diagram of 1 (Fig. 3)
scheme. It contains nearly a planar salicylaldimine fragment which
is benzenoid like as shown by most of the azomethines. The
molecule forms both an intramolecular hydrogen bond,
O(1)ꢀ(H1).N(1) 2.649(3) and intermolecular hydrogen bond,
N(2)ꢀH(2).O(2) 2.866 Å; the O(1)H(1)N(1) angle is 136ꢂ (Table 6).
The N(1)eC(7) and O(2)eC(8) bond length (1.275(6), 1.227(7) Å)
indicates double bond character. However, the N(1)eN(2), N(2)e
C(8) and O(1)eC(6) bond lengths (1.377(6),1.323(7) and 1.348(6) Å)
are in close agreement with the single bond values reported in
literature [29]. The original formyl group is retained in the crystal
structure and is at trans position to the phenolic hydroxyl group.
The data pertaining to inter and intra-molecular hydrogen bonds is
provided in Table 6.
confirmed secondary NCH—N, Sn—O,
p—H and O—H interactions,
resulting in a supramolecular cage structure.
Crystal data and selected interatomic parameters for compound
4 are collected in Tables 10 and 11, respectively. An ORTEP view of
the molecule 4 including numbering scheme is shown in Fig. 4. The
Sn is coordinated to the carbon of two phenyl groups and a tri-
dentate ligand that is bonded to the Sn via a phenolic oxygen O(1),
azomethine nitrogen N(1) and amide oxygen O(2). For compound 4,
the geometry around Sn is a midway between trigonal bipyramidal
3.3. X-ray structure of 1 and 4
The asymmetric unit of 1 contains two different molecules;
a stereoview of the molecules and atomic numbering scheme are
shown in Fig. 2, while crystal data and selected bond lengths and
bond angles are given in Tables 7 and 8, respectively. The structure
of complex 1 consists of a deprotonated ONO dibasic tridentate
ligand bonded to the (CH3)2Sn(IV) moiety via two oxygen and
a nitrogen atom, forming a O2NC2 core around the Sn atom. The
ligand is non-planar, probably due to the steric requirements of
and square-pyramidal as evident from the
s value, 0.5. The equa-
torially positions are occupied by the nitrogen atom and two ipso-
carbon of the phenyl groups; the two oxygen atoms are present at
the apical position. The angle of O(1)Sn(1)O(2) is 157.29(14)ꢂ. Sn(1)
atom form a six membered ring with O(1), C(1), C(6), C(7), N(1)
atoms, while the Sn(1) atom forms a five membered ring with O(2),
C(8), N(2) and N(1) atoms. The SneO(1) and SneO(2) bond lengths
(2.068(3) and 2.140(3) Å) are less than the sum of Van der Waals
radii of Sn and O (2.8 Å). The low values of O(1)eSneN(1), and
O(2)eSneN(1) angles are 84.32ꢂ and 73.04ꢂ, respectively, and are
significantly different to those expected for a regular geometry. The
SneN(1) bond distance, 2.160 Å, is comparable to the sum of
covalent radii of Sn and N (2.15 Å) and has considerably lower value
than the sum of Van der Waals radii (3.75 Å) of the two atoms
suggesting a strong tin-nitrogen bond. The C(1)eO(1) and C(8)e
O(2) bond length (1.313 Å, 1.274 Å) are in agreement with the re-
ported values [31].
the five and six membered chelate rings formed. The
important parameter to decide the geometry of five-coordinated
metal and can be calculated by using equation )/60 [30],
¼ (
where and are the consecutive largest of the basal angles
around the Sn atom. For five-coordinated Sn with a perfect
trigonal-bipyramidal geometry value is one whereas a value of
zero corresponds to a perfect square-pyramidal structure. The two
molecules have a bit different geometry as clear from value, (0.5
and 0.37). The value 0.5 for molecules one indicates a geometry
s value is an
s
b-a
b
a
s
s
s
midway between trigonal bipyramidal and square-pyramidal
while distorted square-pyramidal geometry can be assigned to
the second molecule. The different geometry of molecule 2 from
that of molecule 1 may be due to less crowding of Sn center as
evident from large H3CeSneCH3 angle (155.19ꢂ). The methyl
The packing diagram (Fig. 5) indicates a dimeric structure for
compounds 4 in which the two molecules are linked together via
non-covalent secondary Br—Br intermolecular interactions with
a distance of 3.589 Å. The intramolecular hydrogen bond, H—Br,
Fig. 1. ORTEP drawing of H2Le with the atomic numbering scheme. The dashed line indicates hydrogen bonds.

S. Shujah et al. / Journal of Organometallic Chemistry 696 (2011) 2772e2781
2777
Fig. 2. ORTEP drawing of complex 1 with the atomic numbering scheme.
Fig. 3. Supramolecular cage structure of for one of the two molecules of compound 1 showing intermolecular Sn—O interactions.

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S. Shujah et al. / Journal of Organometallic Chemistry 696 (2011) 2772e2781
Table 7
Table 9
Crystal data and structure refinement parameters for compounds 1.
Bond distances (Å) and bond angles (ꢂ) for compound 1 (molecule 2).
Empirical formula
C10H11BrN2O2Sn
Bond lengths
Formula mass
Crystal system
Space group
a (Å)
b (Å)
c (Å)
425.26
Monoclinic
P 21/c
11.4406(5)
15.6641(6)
14.4624(7)
90.00
98.39(2)
90.00
2563.9(2)
4
Block
0.449 ꢃ 0.40 ꢃ 0.38
296 (2)
1.102
Sn(2)eO(3)
Sn(2)eC(20)
Sn(2)eC(19)
Sn(2)eO(4)
Sn(2)eN(3)
O(4)eC(18)
Bond angles
O(3)eC(11)eC(12)
O(3)eC(11)eC(16)
N(3)eC(17)eC(16)
O(4)eC(18)eN(4)
C(17)eN(3)eN(4)
C(17)eN(3)eSn(2)
N(4)eN(3)eSn(2)
C(18)eN(4)eN(3)
O(4)eSn(2)eN(3)
C(11)eO(3)eSn(2)
2.086(5)
2.100(8)
2.110(10)
2.166(5)
2.169(5)
1.270(10)
C(17)eN(3)
C(18)eO(4)
C(18)eN(4)
N(3)eN(4)
O(3)eC(11)
1.285(9)
1.270(10)
1.277(10)
1.418(8)
1.327(8)
a
b
g
(ꢂ)
(ꢂ)
(ꢂ)
119.46(7)
122.47(6)
125.91(6)
128.68(5)
114.48(6)
129.07(5)
116.29(4)
109.58(6)
72.68(2)
C(18)eO(4)eSn(2)
O(3)eSn(2)eC(20)
O(3)eSn(2)eC(19)
O(3)eSn(2)eO(4)
O(3)eSn(2)eN(3)
C(20)eSn(2)eC(19)
C(20)eSn(2)eO(4)
C(20)eSn(2)eN(3)
C(19)eSn(2)eO(4)
C(19)eSn(2)eN(3)
112.73(5)
92.93(3)
95.44(4)
155.19(2)
82.74(2)
132.47(4)
94.72(3)
115.78(3)
96.68(4)
111.68(3)
V (Å3)
Z
Crystal habit
size (mm)
T (K)
r
m
(g.cmꢀ3
)
(Mo Ka) (mmꢀ1
)
2.654
812
F(000)
133.60(4)
Total reflections
7059
Independent reflections
4723
For ðFo ꢄ 4:0
s
ðFoÞÞ
4.2. Antibacterial activity
P
P
RðFÞ ¼ ðjjFoj ꢀ jFcjjÞ= jFoj
0.048
For F0>4.0
s
(F0)
P
P
The schiff base ligand and its diorganotin(IV) derivatives were
screened for their antibacterial activity against 2 gram-positive
(Bacillus subtilis, Staphylococcus aureus) and 4 gram-negative
wRðF2Þ ¼ ½ ½wðFo2 ꢀ Fc2Þ2ꢅ= ½wðFo2Þ2ꢅꢅ1=2
0.127
1.138
1.93e30.54
4723/0/361
Goodness-of-fit
q
Range (deg)
Data/restrictions/params
bacteria (Eschericha coli, Shigella flexenari, Pseudomonas aeruginosa,
Salmonella typhi) using Imipenem (C12H17N3O4S) is used as a stan-
dard drug for comparison (Fig. 7). Most of the diorganotin(IV)
derivatives significantly inhibit gram-positive bacterial growth.
This may be due to the ease of permeation of the complexes owing
to the simplicity of the cell wall of these strains. The high bacteri-
cidal activity of organotin derivatives than the parent ligand is most
probably due to the reduction in the polarity of the central Sn atom
upon coordination with the ligand. Two main factors are respon-
sible for this reduction in polarity; firstly because of the partial
sharing of its positive charge with donor groups and secondly due
exits in both molecules, however, the bond value is not exactly the
same (2.954 and 2.758 Å); the difference of about 0.196 Å is there.
4. Biological activities
4.1. Antifungal activity
The antifungal activity of synthesized compounds was tested
in vitro against human pathogenic fungal strains including yeasts
(Candida albicans ATCC 2192, Candida glabrata ATCC 90030),
dermatophytes (Microsporum canis ATCC 9865, Trichphyton long-
ifusus ATCC 22397), opportunistic molds (Aspergillus flavus ATCC
1030 and Fusarium solani ATCC 11712) by using the agar tube
dilution test. The parent ligand (H2L) is inactive against all the
studied strain except M. canis and F. solani, where the ligand has
comparable activity to the standard drug, especially against the
latter strain. In general 1, 2 and 7 are the least active organotin
derivatives. The activities of complexes 3e6 are fairly good, espe-
cially against A. flavus and F. solani. The strain C. glabrata is quite
resistant to all complexes (Fig. 6).
to
p-electrons delocalization within the whole chelating ring. As
consequence, the lipophilic nature of the central Sn atom increases,
which favors the permeation of the complexes through the lipid
layer of the cell membrane [32].
Table 10
Crystal data and structure refinement parameters for compound (4).
Empirical formula
C20H15BrN2O2Sn
Formula mass
Crystal system
Space group
a (Å)
b(Å)
c(Å)
513.94
Monoclinic
P 21/c
19.514(13)
10.917(7)
9.196(5)
90.00
95.44(2)
90.00
a
b
g
(ꢂ)
(ꢂ)
(ꢂ)
Table 8
Bond distances (Å) and bond angles (ꢂ) for compound 1 (molecule 1).
V(Å3)
1950.1(2)
4
Bond lengths
Z
Sn(1)eC(9)
Sn(1)eC(10)
Sn(1)eO(1)
Sn(1)eO(2)
Sn(1)eN(1)
O(2)eC(8)
2.089(8)
2.095(5)
2.106(5)
2.145(5)
2.205(5)
1.284(9)
N(1)eC(7)
N(1)eN(2)
N(2)eC(8)
C(8)eO(2)
O(1)eC(1)
1.286(8)
1.403(8)
1.293(10)
1.284(9)
1.321(8)
Crystal habit
size (mm)
Block
0.49 ꢃ 0.43 ꢃ 0.39
r
(g.cmꢀ3
)
1.750
m
(Mo Ka) (mmꢀ1
)
3.375
1000
5915
F(000)
Total reflections
Bond angles
Independent reflections
3012
C(1)eO(1)eSn(1)
O(1)eC(1)eC(2)
O(1)eC(1)eC(6)
N(1)eC(7)eC(6)
O(2)eC(8)eN(2)
C(7)eN(1)eSn(1)
N(2)eN(1)eSn(1)
C(9)eSn(1)eO(2)
130.13(4)
118.82(6)
122.90(6)
126.11(6)
126.84(7)
127.85(4)
115.52(4)
98.65(3)
C(8)eO(2)eSn(1)
C(10)eSn(1)eC(9)
O(1)eSn(1)eC(9)
O(1)eSn(1)eO(2)
O(1)eSn(1)eN(1)
C(9)eSn(1)eN(1)
O(2)eSn(1)eN(1)
C(10)eSn(1)eN(2)
114.18(5)
132.92(3)
97.46(3)
152.28(2)
81.50(19)
105.15(3)
72.59(19)
121.90(3)
For ðFo ꢄ 4:0
s
ðFoÞÞ
P
P
RðFÞ ¼ ðjjFoj ꢀ jFcjjÞ= jFojj
0.038
For ðFo > 4:0
s
ðFoÞÞ
P
P
wRðF2Þ ¼ ½ ½wðFo2 ꢀ Fc2Þ2ꢅ= ½wðFo2Þ2ꢅꢅ1=2
0.095
1.022
1.05e30.49
3012/12/234
ꢀ0.423 and 0.671
Goodness-of-fit
Range (deg)
q
Data/restrictions/params
Largest diff. peak and hole (eÅꢀ3
)

S. Shujah et al. / Journal of Organometallic Chemistry 696 (2011) 2772e2781
2779
Table 11
Selected bond lengths (Å) and bond angles (ꢂ) of compound (4).
Bond lengths
Sn(1)eO(1)
Sn(1)eC(15)
Sn(1)eC(9)
Sn(1)eO(2)
2.068(3)
2.107(2)
2.133(4)
2.140(3)
2.160(4)
N(1)eN(2)
N(2)eC(8)
O(1)eC(1)
O(2)eC(8)
N(1)eC(7)
1.401(5)
1.284(7)
1.313(4)
1.274(7)
1.290(5)
Sn(1)eN(1)
Bond angles
C(1)eO(1)eSn(1)
O(1)eC(1)eC(2)
O(1)eC(1)eC(6)
N(1)eC(7)eC(6)
O(2)eC(8)eN(2)
C(10)eC(9)eSn(1)
C(14)eC(9)eSn(1)
C(16)eC(15)eSn(1)
C(20)eC(15)eSn(1)
C(7)eN(1)eSn(1)
N(2)eN(1)eSn(1)
132.82(2)
119.27(3)
123.11(4)
126.84(4)
127.53(3)
121.89(4)
119.42(4)
121.40(4)
118.57(19)
127.68(3)
116.18(3)
C(8)eO(2)eSn(1)
O(1)eSn(1)eC(15)
O(1)eSn(1)eC(9)
O(1)eSn(1)eO(2)
O(1)eSn(1)eN(1)
C(15)eSn(1)eC(9)
C(15)eSn(1)eO(2)
C(15)eSn(1)eN(1)
C(9)eSn(1)eO(2)
C(9)eSn(1)eN(1)
O(2)eSn(1)eN(1)
113.20(3)
94.62(12)
94.54(14)
157.29(14)
84.32(12)
127.49(15)
95.50(15)
120.45(12)
95.33(16)
111.86(13)
73.04(15)
Fig. 4. ORTEP drawing of complex 4 with the atomic numbering scheme.
tericin B (0.50 mg/mL) as standard drug (Table 12). The complexes
4.3. Anti-leishmanial activity
(1e7) are more active than the parent ligand. The complexes
activity decreases in the following order: 3 > 6 > 2 > 4 > 1 > 5 > 7. The
activity of the complexes 2, 4 and 6 is as good as standard drug. The
The Anti-leishmanial activity of ligand and complexes (1e7) was
obtained against the pathogenic Leishmania major, using Ampho-
Fig. 5. Dimeric structure of compound 5 due to the presence of BreBr interaction.
Fig. 6. Antifungal activity of H2Le and its organotin(IV) derivatives against various fungi.

2780
S. Shujah et al. / Journal of Organometallic Chemistry 696 (2011) 2772e2781
Fig. 7. Antibacterial activitya,b of N0-(5-bromo-2-hydroxybenzylidene)formohydrazide (H2Le) and its organotin(IV) complexes.
high activity of 3 and 6 than 2 can be explained on the basis their
high lipophilic character. The low activity of tert-butyltin(IV)
derivative (6) than n-butlyltin(IV) compound (3) may be due to
reduce planarity of the former that slow down the complex diffu-
sion. The high activity of 4 than 1 can be attributed to its planarity
and lipophilicity. The low activity of 5 may be due to its high
molecular weight that turn into reduction of its permeability. The
lowest activity of the chlorobutyltin(IV) complex confirms the idea
that monorganotins are least toxic than diorganotins [33]. The
compound 3 inhibits the leishmanial growth even more effectively
than Amphotericin B, and thus has a potential to be marketed as
leishmanicidal agents.
4.4. Antiurease activity
Parent ligand and its complexes were tested for their in vitro
urease inhibition activities at 0.5 mM concentration against jack
bean urease. The urease inhibition activity was undertaken
according to the literature protocols [34], using thiourea as the
standard inhibitor having an IC50 value of 21 ꢁ 0.01
mM. The results
are presented in Table 13.The parent ligand and its organotin(IV)
derivatives displayed moderate inhibition.
5. Conclusion
In summing up, seven new diorganotin(IV) compounds of
[N0-(5-bromo-2-oxidobenzylidene)-N-(oxidomethylene)hydrazine
have been synthesized and characterized by IR, NMR, mass spec-
troscopy and elemental analysis. The crystal structure of the parent
ligand, dimethyl- and diphenyltin(IV) derivatives has also been
determined by X-ray single crystal diffraction analyses. Both
dimethyl- and diphenyltin(IV) derivatives have a distorted square-
pyramidal (supramolecular structure) and a distorted trigonal-
bipyramidal (dimeric structure) geometry, respectively. The
synthesized complexes showed moderate antibacterial, antifungal
and antiurease activities. Most of the complexes showed leishma-
nicidal activity comparable to those of standard drug. The highest
Table 12
Antileishmanial activityaed of selective ligands and their organo-
tin(IV) complexes.
Compound No.
IC50
(
m
g/mL) ꢁ S.D
H2Le
(1)
(2)
(3)
(4)
(5)
(6)
(7)
22.07 ꢁ 0.33
4.28 ꢁ 0.03
2.26 ꢁ 0.02
0.41 ꢁ 0.05
2.51 ꢁ 0.01
5.21 ꢁ 0.04
1.22 ꢁ 0.02
8.11 ꢁ 0.04
activity was noted for complex 3 [IC50
that exceeds the standard drug, the Amphotericin. B [IC50
(
m
g/mL) ꢁ S.D ¼ 0.41 ꢁ 0.05],
a
Test organism: Leishmania major (DESTO).
Standard drug: Amphotericin. B (
Incubation period: 72 h.
Incubation temperature: 22 ꢁ 1 ꢂC.
(
mg/
b
c
m
g/mL) ꢁ S.D ¼ 0.50 ꢁ 0.02.
mL) ꢁ S.D ¼ 0.50 ꢁ 0.02] and may be used as a new metal-based
d
leishmanicidal drug in future.
Acknowledgments
Table 13
Antiurease activity of representative ligands and their organotin(IV) complexesa,b,c,d
We thank the Higher Education Commission of Pakistan for
financial support.
Compound No.
% Inhibition
H2Le
(1)
(2)
(3)
(4)
(5)
(6)
(7)
45.1
36.5
27.3
18.1
28.0
20.1
16.2
18.2
IC50 ꢁ S.D [
m
M]
e
e
e
e
e
e
e
e
Appendix A. Supplementary data
a
Sample Concentration [mM] 0.5.
b
c
Standard: Thiourea, IC50 ꢁ SEM [ M], 21.0 ꢁ 0.11.
m
CCDC 815286, 815288 and 815288 contains the supplementary
crystallographic data for H2Lcomplexes 1 and 4, respectively. These
Proposed implications of inhibitor : Acute ulcer.
d
IC50 reported for those compounds whose % inhibition is more than 55%.

S. Shujah et al. / Journal of Organometallic Chemistry 696 (2011) 2772e2781
2781
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