Triorganotin(IV) complexes with o-substituted arylhydroxamates: Synthesis, spectroscopic characterization, X-ray structures and in vitro cytotoxic activities

Article abstract of DOI:10.1016/j.jorganchem.2014.04.015

Six new triorganotin(IV) complexes with six different RN-2-X- benzohydroxamic acid ligands having general formula R′C(O)N(RN)OH (R′ = alkyl/aryl; RN = alkyl/aryl or H), (X = -I, -NO₂, -OCH₃, -Br and R = -CH₃, -C₆

Full text of DOI:10.1016/j.jorganchem.2014.04.015

Journal of Organometallic Chemistry 763-764 (2014) 26e33
Contents lists available at ScienceDirect
Journal of Organometallic Chemistry
journal homepage: www.elsevier.com/locate/jorganchem
Triorganotin(IV) complexes with o-substituted arylhydroxamates:
Synthesis, spectroscopic characterization, X-ray structures and in vitro
cytotoxic activities
,
b
,
a
,
c
d
Naqeebullah Khan a , Yang Farina , Lo Kong Mun , Nor Fadilah Rajab ,
*
*
Normah Awang e
a School of Chemical Sciences and Food Technology, Faculty of Science & Technology, University Kebangsaan Malaysia, 43600 Bangi, Selangor Darul Ehsan,
Malaysia
b Department of Chemistry, Faculty of Physical Sciences, University of Balochistan, Sariab Road, Quetta 87300, Pakistan
c Department of Chemistry, Faculty of Science, University of Malaya, 50603 Kuala Lumpur, Malaysia
d Biomedical Science Programme, Faculty of Health Sciences, University Kebangsaan Malaysia, Jalan Raja Muda Abdul Aziz, 50300 Kuala Lumpur, Malaysia
e Environmental Health Programme, Faculty of Allied Health Sciences, Universiti Kebangsaan Malaysia, Jalan Raja Muda Abdul Aziz, 50300 Kuala Lumpur,
Malaysia
a r t i c l e i n f o
a b s t r a c t
Article history:
Six new triorganotin(IV) complexes with six different RN-2-X-benzohydroxamic acid ligands having
general formula R0C(O)N(RN)OH (R0 ¼ alkyl/aryl; RN ¼ alkyl/aryl or H), (X ¼ eI, eNO2, eOCH3, eBr and
R ¼ eCH3, eC6H5 and eC6H4eCH3), were prepared by condensation method with the respective orga-
notin(IV) chlorides using a stoichiometric ratio of 1:1. The bonding and coordination behaviour of these
complexes were investigated on the basis of FT-IR, multinuclear 1H, 13C and 119Sn NMR spectroscopies.
Complexes (1) and (3) crystallize in the orthorhombic P2(1)2(1)2(1) space group and complex (2)
crystallizes in the triclinic P-1 space group whereas complex (4) crystallizes in the monoclinic P2(1)/c
space group. The tested triphenyltin(IV) complexes showed significant cytotoxicities, higher than
doxorubicin toward K-562, Jurkat, HepG2 and L929 cells.
Received 4 January 2014
Received in revised form
11 April 2014
Accepted 13 April 2014
Keywords:
Triorganotin(IV) complex
Hydroxamic acid
NMR
Crystal structure
Cytotoxicity
Ó 2014 Elsevier B.V. All rights reserved.
Introduction
acids are usually used as supporting ligands in organometallic
chemistry and biology because of their tautomerization and po-
Since Lossen discovered the first hydroxamic acid more than
100 years ago, a considerable attention has been given to the
preparation, structureeactivity relationships (SAR), utilization, and
biological applications of hydroxamates [1,2]. These compounds are
capable of the inhibition of a variety of enzymes, including ureases,
peroxidases and matrix metalloproteinases [3e6]. In the biomed-
ical sciences, hydroxamic acid moieties are used in the design of
therapeutics targeting cancer, cardiovascular diseases [7,8]. In
addition, the hydroxamic acids have been employed as insecticides,
antimicrobials [9,10]. These compounds also show prominent ac-
tivities due to their chelating properties with metal ions, hence
constituting a very important class of chelating agents. Hydroxamic
tential as therapeutics agents [11,12]. The principal coordination
mode observed in metalehydroxamic acid complexes is the O,O-
bidentate chelation, in which the ligand is either singly deproto-
nated (hydroxamato) or doubly (RN ¼ H) deprotonated (hydrox-
imato) [13].
Organotin(IV) complexes with bidentate O-donor ligands [14],
including N-substituted hydroxamic acids, are well known and
have been a continuing subject of study in the recent years [15],
highlighting the synthesis of a number of complexes with inter-
esting properties [16,17]. The triorganotin(IV) derivatives of
bidentate ligands have been widely explored to have tetrahedral
[18,19] or trigonal bipyramidal [20e23] geometry depending upon
the nature of organo group and also the electronegativity of the
atoms attached with central tin atom. Organotin compounds are a
widely studied class of organometallic compounds with, broad
spectrum of applications, being used in antifouling paints [24], PVC
stabilization [25], as homogeneous catalysts [26], and as ion car-
riers in electrochemical membranes design [27], and in agriculture
* Corresponding authors. School of Chemical Sciences and Food Technology,
Faculty of Science & Technology, University Kebangsaan Malaysia, 43600 Bangi,
Selangor Darul Ehsan, Malaysia. Tel.: þ60 3 8921 3901; fax: þ60 3 89215410.
E-mail addresses: bionaqeeb@yahoo.com, naqeebhmd2@gmail.com (N. Khan),
farina@ukm.my (Y. Farina).
http://dx.doi.org/10.1016/j.jorganchem.2014.04.015
0022-328X/Ó 2014 Elsevier B.V. All rights reserved.

N. Khan et al. / Journal of Organometallic Chemistry 763-764 (2014) 26e33
27
that give rise to ubiquitous environmental contamination [28,29].
Organotins compounds have been the source of much biochemical
interest due to the fact that they display a number of biological
activities [17,30e32], Moreover, the increasing interest in the
chemistry of organotin(IV) compounds has led to the extended
studies against cancer [33e37]. The biological activity of organotin
compounds is mainly determined by the number and nature of
organic groups linked to the central tin atom. The biological activity
of OTC generally decreases in the following order:
R3Snþ>R2Sn2 þ>RSn3 þ [17,38e40], which has been related to their
ability to bind to proteins. The genotoxicity of tri-n-butyltins and
triphenyltins in mammalian cells have also been reported [29,41].
In this work, we carried out systematic studies of tri-
organotin(IV) derivatives of six different hydroxamic acid ligands.
We further report here the spectral characterization, X-ray
diffraction studies and the in vitro cytotoxic activities of the four
compounds against four different cell lines; i.e., human leukemic
lymphoblastoma K-562 cells, lymphoblastoma Jurkat cells, hep-
atoblastoma HepG2 cells and mouse fibroblast L929 cells.
NMR [DMSO-d6]: (ppm) ¼ 162.45 (C]O); 145.79 [C(1)], 125.02
[C(2)], 128.66e134.44 [C(3e6)], 37.13 [C(8)].
[HONCH3C(O)C6H4OCH3-2] (HL3). Colorless crystals. Yield: 69%.
Melting point: 136e137 ꢁC. Elemental Analysis Calcd. (%) for
H
11C9NO3: C 59.66, H 6.08, N 7.73. Found (%): C 59.31, H 6.76, N 8.52.
Selected IR data (KBr pellets, cmꢀ1): 3126 (s, br,
nOeH),1603 (s, nC]
O), 1486 (s,
n
CeN) and 918 (s,
n
NO). 1H NMR [CDCl3]: (ppm) ¼ 9.10
[s, br, 1H, OH]; 6.99e7.50 [m, 4H]; 3.86 [s, 3H] 3.23 [s, 3H]. 13C NMR
[CDCl3]: (ppm) ¼ 166.02 (C]O); 155.94 [C(1)], 111.24 [C(2)],
119.97e133.56 [C(3e6)], 36.78 [C(8)], 55.68 [C(9)].
[HONCH3C(O)C6H4Br-2] (HL4). Colorless crystals. Yield: 79%.
Melting point: 127e128 ꢁC. Elemental Analysis Calcd. (%) for
H8C8NO2Br: C 41.76, H 3.48, N 6.10. Found (%): C 39.60, H 2.98, N
6.01. Selected IR data (KBr pellets, cmꢀ1): 3123(s, br,
n
OeH), 1600 (s,
n
C]O), 1436 (s, nCeN) and 915 (s, n
NO). 1H NMR [CDCl3]:
(ppm) ¼ 10.39 [s, br, 1H, OH]; 7.22e7.64 [m, 4H]; 3.86 [s, 3H] 3.24 [s,
3H]. 13C NMR [CDCl3]: (ppm) ¼ 166.76 (C]O); 159.11 [C(1)], 111.24
[C(2)], 119.97e133.56 [C(3e6)], 36.78 [C(8)].
[HONC6H5C(O)C6H4OCH3-2] (HL5). Yellowish solid. Yield: 76%.
Melting point: 116e117 ꢁC. Elemental Analysis Calcd. (%) for
H
13C14NO3: C 69.14, H 5.35, N 5.76. Found (%): C 71.97, H 5.58, N
5.74. Selected IR data (KBr pellets, cmꢀ1): 3239 (s, br,
OeH), 1627
NO). 1H NMR [CDCl3]:
Experimental
n
(s, nC]O), 1490 (s, nCeN) and 900 (s, n
Materials and physical measurements
(ppm) ¼ 9.89 [s, br, 1H, OH]; 6.74e7.59 [m, 9H]; 3.54 [s, 3H]. 13C
NMR [CDCl3]: (ppm) ¼ 165.21 (C]O); 158.51 [C(1)], 111.65 [C(2)],
117.74e135.03 [C(3e13)], 56.68 [C(8)].
The chemicals were purchased from Aldrich and were used as
received. All the chemicals were of analytical grade. The purity of
the ligand and the derived complexes were assured by TLC using
silica gel-G as adsorbent. The melting points were determined in
open capillary tubes using an electrothermal 9300 digital melting
point apparatus. Carbon, hydrogen and nitrogen analysis were
preformed on an Elemental Fison EA 1108 CHNSeO Analyzer. Tin
was determined gravimetrically. Solid state infrared spectra of the
compounds are recorded in the range 4000e400 cmꢀ1. The infrared
spectra were recorded as KBr discs using a PerkineElmer spectro-
photometer GX. The 1H, 13C and 119Sn nuclear magnetic resonance
spectra were recorded using the BRUKER FT-NMR 600 MHz Cryo-
Prob spectrometer and the JEOL JNM-ECP 400 spectrometer, us-
ing DMSO as a solvent and tetramethylsilane as an internal
standard.
[HONCH3C6H4C(O)C6H4NO2-2] (HL6). Yellow solid. Yield: 73%.
Melting point: 172e173 ꢁC. Elemental Analysis Calcd. (%) for
H
12C14N2O4: C 61.76, H 4.41, N 10.29. Found (%): C 60.37, H 4.02, N
10.68. Selected IR data (KBr pellets, cmꢀ1): 3084 (s, br,
n
OeH), 1679
(s, nC]O), 1534 (s, nCeN) and 917 (s, n
NO). 1H NMR [DMSO-d6]:
(ppm) ¼ 10.60 [s, br, 1H, OH]; 7.36e8.14 [m, 8H]; 2.38 [s, 3H]. 13
C
NMR [DMSO-d6]: (ppm) ¼ 166.01 (C]O); 145.56 [C(1)], 114.00
[C(2)], 121.87e142.32 [C(3e13)], 20.86 [C(14)].
Synthesis of complexes
The complexes (1e6) were synthesized by dissolving the free
ligand (1 mM) and potassium hydroxide (1 mM) in 30 ml of
methanol and stirred for 4 h at room temperature. Then added
triphenyltin(IV) chloride (1 mM) dissolved in 15 ml of tetrahydro-
furan (THF) and refluxed for 12e13 h. The solution was then cooled
and filtered. The filtrate was placed under vacuum to evaporate the
solvent to afford the crystals. In some cases the complexes are
recrystallized in methanol.
Synthesis
Synthesis of ligands
The N-methyl o-substituted benzohydroxamic acids (HL1, HL2,
HL3 and HL4), were prepared by the reaction of the respective
benzoyl chloride (10 mM) with N-methylhydroxyl-amine (10 mM)
[42] while N-phenyl o-methoxybenzohydroxamic acid (HL5) and N-
tolyl o-nitrobenzohydroxamic acid (HL6) were prepared by treating
with N-phenyl- and N-tolyl-hydroxylamine (10 mM) in the pres-
ence of sodium hydrogen carbonate (20 mM) [42,43].
[Ph3SnONCH3C(O)C6H4I-2] (1). Colorless crystals. Yield: 68%.
Melting point: 153e154 ꢁC. Elemental Analysis Calcd. (%) for
H
22C26NO2ISn: C, 49.83; H, 3.54; N, 2.24; Sn, 19.01. Found (%): C,
49.61; H, 3.44; N, 2.34; Sn, 18.26. Selected IR data (KBr pellets,
cmꢀ1): 1600 (s,
and 576 (s,
nC]O), 1530 (s, nCeN), 953 (s, nNO), 439 (s, nSneO)
n
SneC). 1H NMR [600 MHz, CDCl3]: (ppm) ¼ 6.76 (m, 4H,
3J(1He1H) ¼ 18 Hz, aromatic H in HL1), 7.37 (m, 9H, m- and p-
protons in SnPh3), 7.74 (m, 6H, 3J(1HeSn) ¼ 24 Hz, o-protons in
SnPh3); 3.31 [s, 3H]. 13C NMR [600 MHz, CDCl3]: (ppm) ¼ 163.69
(C]O); 94.02, 138.13 (C-2 and C-4 of HL1) 131.37 (C-6 of HL1),
128.28 (C-1 of SnPh3, 1J(13CeSn) ¼ 96 Hz), 128.07 (C-5 of HL1),
128.56 (C-3 and C-5 in SnPh3, 3J(13CeSn) ¼ 234 Hz), 136.8 (C-2 and
C-6 in SnPh3, 2J(13CeSn) ¼ 96 Hz), 139.42 (C-1 of HL1), 128.95 (C-4
in SnPh3), 144.48 (C-3 of HL1); 39.29 (NeC). 119Sn NMR [CDCl3]:
(ppm) ¼ ꢀ147.
[HONCH3C(O)C6H4I-2] (HL1). Colorless crystals. Yield: 84%.
Melting point: 134e135 ꢁC. Elemental Analysis Calcd. (%) for
H8C8NO2I: C 34.67, H 2.89, N 5.06. Found (%): C 35.32, H 2.71, N 4.93.
Selected IR data (KBr pellets, cmꢀ1): 3114 (s, br,
n
OeH), 1608 (s,
nC]
O), 1494 (s,
nCeN) and 915 (s, n
NO). 1H NMR [DMSO-d6]:
(ppm) ¼ 10.28 [s, br, 1H, OH]; 7.09-7.86 [m, 4H]; 3.24 [s, 3H]. 13C
NMR [DMSO-d6]: (ppm) ¼ 169.02 (C]O); 165.95 [C(1)], 93.39
[C(2)], 127.68e142.56 [C(3e6)], 38.88[C (8)].
[HONCH3C(O)C6H4NO2-2] (HL2). Yellow crystals. Yield: 76%.
Melting point: 169e170 ꢁC. Elemental Analysis Calcd. (%) for
H8C8N2O4: C 48.98, H 4.08, N 14.28. Found (%): C 49.12, H 4.12, 14.10.
[Ph3SnONCH3C(O)C6H4NO2-2] (2). Yellow crystals. Yield: 74%.
Melting point: 134e135 ꢁC. Elemental Analysis Calcd. (%) for
H
22C26N2O4Sn: C, 57.23; H, 4.07; N, 5.14; Sn, 21.83. Found (%): C,
Selected IR data (KBr pellets, cmꢀ1): 3100(s, br,
nOeH), 1601 (s, nC]
56.87; H, 3.83; N, 5.78; Sn, 20.27. Selected IR data (KBr pellets,
O), 1524 (s,
n
CeN) and 916 (s,
n
NO). 1H NMR [DMSO-d6]:
cmꢀ1): 1603 (s,
and 507 (s,
nC]O), 1527 (s, nCeN), 937 (s, nNO), 450 (s, nSneO)
(ppm) ¼ 8.74 [s, br, 1H, OH]; 7.27e7.69 [m, 4H]; 3.21 [s, 3H]. 13C
n
SneC). 1H NMR [600 MHz, DMSO-d6]: (ppm) ¼ 8.23 (m,

28
N. Khan et al. / Journal of Organometallic Chemistry 763-764 (2014) 26e33
4H, 3J(1He1H) ¼ 48 Hz, aromatic H in HL2), 7.61 (m, 9H, m- and p-
protons in SnPh3), 7.28 (m, 6H, 3J(1HeSn) ¼ 12 Hz, o-protons in
SnPh3); 3.23 (s, 3H) 13C NMR [600 MHz, DMSO-d6]: (ppm) ¼ 160.43
(C]O); 146.06, 132.21 (C-2 and C-4 of HL2) 125.54 (C-6 of HL2),
128.44 (C-1 of SnPh3, 1J(13CeSn) ¼ 120 Hz), 145.56 (C-5 of HL2),
128.81 (C-3 and C-5 in SnPh3, 3J(13CeSn) ¼ 24 Hz), 136.53(C-2 and
C-6 in SnPh3, 2J(13CeSn) ¼ 90 Hz), 124.06 (C-1 of HL2), 128.85 (C-4
in SnPh3), 123.21 (C-3 of HL2); 39.66 (NeC). 119Sn NMR [DMSO-d6]:
(ppm) ¼ ꢀ205.
(C-6 of HL6), 129.10 (C-1 of SnPh3, 1J(13CeSn) ¼ 144 Hz), 141.99 (C-5
of HL6), 129.35 (C-3 and C-5 in SnPh3, 3J(13CeSn) ¼ 126 Hz),
136.53(C-2 and C-6 in SnPh3, 2J(13CeSn) ¼ 54 Hz), 123.44 (C-1 of
HL6), 130.48 (C-4 in SnPh3), 122.17 (C-3 of HL6). 136.89, 132.21,
129.35 and 128.67 (C-8, C(9)/C(11), C(10)/C(12) and C13 of HL6);
21.29 (CeC). 119Sn NMR [DMSO-d6]: (ppm) ¼ ꢀ210.
X-ray crystallography
[Ph3SnONCH3C(O)C6H4OCH3-2] (3). Colorless crystals. Yield:
81%. Melting point: 119e120 ꢁC. Elemental Analysis Calcd. (%) for
H25 C27NO3Sn: C, 61.11; H, 4.72; N, 2.64; Sn, 22.44. Found (%): C,
61.15; H, 4.67; N, 2.61; Sn, 21.88. Selected IR data (KBr pellets,
The single crystals of triphenyltin(IV) N-methyl o-iodobenzo-
hydroxamte, triphenyltin(IV) N-methyl o-nitrobenzohydroxamate,
triphenyltin(IV) N-methyl o-methoxybenzohydroxamate and tri-
phenyltin(IV) N-methyl o-bromobenzohydroxamate (Figs. 1e4) of
suitable quality were each mounted on a fine glass capillary and
cmꢀ1): 1590 (s,
O) and 695 (s,
nC]O), 1498 (s, nCeN), 973 (s, nNeO), 439 (s, nSne
n
SneC). 1H NMR [600 MHz, DMSO-d6]: (ppm) ¼ 7.17
aligned on the Bruker SMART APEX2 diffractometer, equipped with
(m, 4H, 3J(1He1H) ¼ 120 Hz, aromatic H in HL3), 7.61 (m, 9H, m- and
p-protons in SnPh3), 7.50 (m, 6H, 3J(1HeSn) ¼ 60 Hz, o-protons in
SnPh3); 3.82 (s, 3H); 3.37 (s, 3H). 13C NMR [600 MHz, DMSO-d6]:
(ppm) ¼ 161.09 (C]O); 156.12, 146.03 (C-2 and C-4 of HL3) 128.42
(C-6 of HL3), 128.62 (C-1 of SnPh3, 1J(13CeSn) ¼ 126 Hz), 121.15 (C-5
of HL3), 130.1 (C-3 and C-5 in SnPh3, 3J(13CeSn) ¼ 60 Hz), 136.8 (C-2
and C-6 in SnPh3, 2J(13CeSn) ¼ 90 Hz), 120.68 (C-1 of HL3), 129.25
(C-4 in SnPh3), 112.48 (C-3 of HL3); 39.53 (NeC); 56.18 (OeC). 119Sn
NMR [DMSO-d6]: (ppm) ¼ ꢀ235.
ꢀ
graphite mono-chromated Mo-K
a
radiation source (
l
¼ 0.71073 A).
All data collection was carried out at 100 K and 296 K. The range for
data collection was 2.17e27.20 for (1) and 2.26e26.50 for (2), 1.56e
27.50 for (3) and 2.13e27.50 for (4). All calculations were performed
using the SHELXTL-97 package [44]. The data collection and
refinement parameters are summarized in Table 1.
Cell lines and culture method
[Ph3SnONCH3C(O)C6H4Br-2] (4). Colorless crystals. Yield: 78%.
Melting point: 136e137 ꢁC. Elemental Analysis Calcd. (%) for
K-562 human leukemic carcinoma cells, Jurkat human leukemic
carcinoma cells, HepG2 human hepatocarcinoma cells and L929
mouse fibroblast cells were obtained from American Type Culture
Collection (ATCC, USA). The K-562 cell line was grown and main-
tained in Iscove’s Modified Dulbecco’s Medium (IMDM), Jurkat cells
were grown and maintained in Roswell Park Memorial Institute
(RPMI-1640) medium whereas the HepG2 and L929 cell lines were
grown and maintained in Eagle’s Minimum Essential Medium
(EMEM), (Invitrogen Cooperation, UK) supplemented with 10% FBS
(PAA Laboratories, Australia) and antibiotics (50 U/mL penicillin/
50 mM streptomycin), EMEM was also supplemented with 1% so-
dium pyruvate ((Invitrogen Cooperation, UK), and 1% non-essential
amino acid, maintained at 37 ꢁC with 5% CO2 in humidified air
atmosphere.
H22C26NO2BrSn: C, 53.88; H, 3.83; N, 2.42; Sn, 20.55. Found (%): C,
54.22; H, 3.81; N, 2.41; Sn, 18.96. Selected IR data (KBr pellets,
cmꢀ1): 1601 (s,
and 552 (s,
nC]O), 1497 (s, nCeN), 946 (s, nNO), 450 (s, nSneO)
n
SneC). 1H NMR [600 MHz, CDCl3]: (ppm) ¼ 7.23 (m, 4H,
3J(1He1H) ¼ 48 Hz, aromatic H in HL4), 7.7.33 (m, 9H, m- and p-
protons in SnPh3), 7.56 (m, 6H, 3J(1HeSn) ¼ 90 Hz, o-protons in
SnPh3); 3.30 [s, 3H]. 13C NMR [600 MHz, CDCl3]: (ppm) ¼ 162.02
(C]O); 120.81, 137.04 (C-2 and C-4 of HL4) 127.75 (C-6 of HL4),
128.28 (C-1 of SnPh3, 1J(13CeSn) ¼ 126 Hz), 129.95 (C-5 of HL4),
130.1 (C-3 and C-5 in SnPh3, 3J(13CeSn) ¼ 306 Hz), 136.8 (C-2 and C-
6 in SnPh3, 2J(13CeSn) ¼ 96 Hz), 144.43(C-1 of HL4), 128.95 (C-4 in
SnPh3), 131.53 (C-3 of HL4); 39.14 (NeC). 119Sn NMR [CDCl3]:
(ppm) ¼ ꢀ175.
[Ph3SnONC6H5C(O)C6H4OCH3-2] (5). Yellow amorphous solid.
Yield: 65%. Melting point: 211e212 ꢁC. Elemental Analysis Calcd. (%)
for H27C32NO3Sn: C, 64.84; H, 4.60; N, 2.36; Sn, 20.10. Found (%): C,
64.64; H, 4.41; N, 2.20; Sn, 19.38. Selected IR data (KBr pellets,
MTT cytotoxicity assay
The antitumor activity against carcinoma cells was assayed by
cmꢀ1): 1600 (s,
O) and 695 (s,
n
C]O), 1530 (s, nCeN), 953 (s, nNeO), 439 (s, nSne
the
3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2H-tetrazolium
SneC). 1H NMR [600 MHz, CDCl3]: (ppm) ¼ 6.66 (m,
bromide (MTT) method [45,46]. The suspension cells were cultured
in 96-well plate at a density of 2 ꢂ 106 cells per well, whereas the
adherent cells were cultured at a density of 5 ꢂ 104 cells per well in
n
9H, 3J(1He1H) ¼ 48 Hz, aromatic H in HL1), 7.30 (m, 9H, m- and p-
protons in SnPh3), 7.43 (m, 6H, 3J(1HeSn) ¼ 60 Hz, o-protons in
Ph3Sn); 3.45 (s, 3H, o-OCH3), 2.50. 13C NMR [600 MHz, CDCl3]:
(ppm) ¼ 161.65 (C]O); 155.84, 140.21 (C-2 and C-4 of HL5) 125.50
(C-6 of HL5), 128.11 (C-1 of SnPh3, 1J(13CeSn) ¼ 54 Hz), 122.32 (C-5
of HL5), 128.20 (C-3 and C-5 in SnPh3, 3J(13CeSn) ¼ 42 Hz), 132.09
(C-2 and C-6 in SnPh3, 2J(13CeSn) ¼ 90 Hz), 120.28 (C-1 of HL5),
128.24 (C-4 in SnPh3),111.04 (C-3 of HL5); 131.67,130.34,129.44 and
127.84 (C-9, C(10)/C(12), C(11)/C(13) and C14 of HL5); 56.18 (OeC).
119Sn NMR [DMSO-d6]: (ppm) ¼ ꢀ261.
[Ph3ONCH3C6H4C(O)C6H4NO2-2] (6). Yellow amorphous solid.
Yield: 69%. Melting point: 91e92 ꢁC. Elemental Analysis Calcd. (%)
for H26C32N2O4Sn: C, 61.84; H, 4.19; N, 4.51; Sn, 19.16. Found (%): C,
61.36; H, 4.74; N, 4.87; Sn, 18.55. Selected IR data (KBr pellets,
cmꢀ1): 1611 (s,
and 544 (s,
nC]O), 1499(s, nCeN), 951 (s, nNO), 416 (s, nSneO)
n
SneC). 1H NMR [600 MHz, CDCl3]: (ppm) ¼ 7.88 (m, 8H,
3J(1He1H) ¼ 156 Hz, aromatic H in HL1), 7.35 (m, 9H, m- and p-
protons in SnPh3), 7.54 (m, 6H, 3J(1HeSn) ¼ 90 Hz, o-protons in
SnPh3); 2.08 (s, 3H, p-CH3). 13C NMR [600 MHz, CDCl3]:
(ppm) ¼ 163.42 (C]O); 146.24, 140.09 (C-2 and C-4 of HL6) 125.69
Fig. 1. Thermal ellipsoidal plot of C26H22INO2Sn. Displacement ellipsoids are drawn at
the 50% probability level, and H atoms are shown as spheres of arbitrary radii.

N. Khan et al. / Journal of Organometallic Chemistry 763-764 (2014) 26e33
29
Fig. 2. Thermal ellipsoidal plot of C26H22N2O4Sn. Displacement ellipsoids are drawn at
the 50% probability level, and H atoms are shown as spheres of arbitrary radii.
Fig. 4. Thermal ellipsoidal plot of C26H22BrNO2Sn. Displacement ellipsoids are drawn
at the 50% probability level and H atoms are shown as spheres of arbitrary radii.
a volume of 200
ml and were treated with various concentrations of
the compounds for 24 h. After treatment, 20
m
l of 5 mg/ml MTT
hydroxide (1 mM) in 30 ml of methanol and stirred for 4 h at room
temperature followed by the addition of triphenyltin(IV) chloride
(1 mM) dissolved in 15 ml of tetrahydrofuran (THF). The resulting
mixture was heated under reflux for 12e13 h. The solution was then
cooled and filtered. The filtrate was placed under vacuum to afford
crystals which were recrystallized from methanol (Scheme 2).
The ligands and derived complexes were evaluated for purity by
TLC technique, using silica gel-G as adsorbent. The newly synthe-
sized complexes are either yellow or colorless solids, stable in air,
soluble in common organic solvents. Tin was determined gravi-
metrically, by igniting a known quantity of each complex till con-
stant weight. The triphenyltin(IV) hydroxamates were found to
decompose at 245e300 ꢁC, and after prolong heating the mass
transformed to SnO2 through some undefined intermediates at
360e555 ꢁC.
(SigmaeAlrich, US) was added to each treated cells and further
incubated for 4 h at 37 ꢁC. Subsequently the medium was discarded
from each well and 200
ml of DMSO (Fisher Scientific, UK) was
added for complete dissolution of the formazan crystals, then the
plate was incubated for 10 min followed by gentle shaking for
10 min. The cytotoxic effect of the organotins on K562, Jurkat,
HepG2 and L929 cells was assessed by measuring the absorbance of
each well at 570 nm (MTT). Tests using DMSO (0.5% in each me-
dium) as negative control were performed in parallel. Mean
absorbance for each concentration was expressed as a percentage
of vehicle control absorbance and plotted versus compound con-
centration. All experiments were carried out in triplicate.
Results and discussion
Synthesis of ligands and complexes
Infra-red spectroscopy
The hydroxamic acid ligands (1e6) were prepared by the
dropwise addition of benzoyl chloride (10 mM) to a stirred cold
solution of N-methyl-, N-phenyl- and N-tolylhydroxylamine
(10 mM) containing sodium hydrogen carbonate (20 mM), for
30 min at 04 ꢁC. The solution was filtered and reduced to evaporate
at low pressure which afforded a precipitate, as depicted in
Scheme 1. The precipitate was then dissolved in boiling ethyl ace-
tate to remove any undissolved substance and then the filtrate is
placed in fridge overnight to afford single crystals.
Solid state infrared spectra of all five different ligands and their
complexes have been recorded in the range 4000e400 cmꢀ1. The
principal infrared absorption bands are those due to
n(OeH), n(C]
O), (CeN) and (NeO) stretching vibrations of the hydroxamate
n
n
group observed in the spectrum of free hydroxamic acid. By
comparing the IR spectra of the free ligands (HL1eHL6), with those
of the corresponding triorganotin(IV) complexes illustrated clear
differences. In all cases, n(OeH) stretching modes were absent in
the spectra of the complexes, thus suggesting the deprotonation of
the hydroxamate group on complexation, hence resulting in the
elimination of the Oe/O intramolecular stretch. Similarly, the
The triphenyltin(IV) complexes (1e6) were synthesized by dis-
solving the hydroxamic acid ligands (1 mM) and potassium
n
(C]O) observed in the range 1679e1601 cmꢀ1, in the ligand are
shifted to lower wave numbers in the range 1611e1590 cmꢀ1 for
the complexes, thus indicating the reduced electron density in the
(C]O) bond due to the oxygen coordinating with the tin centers.
Moreover, the (NeO) stretching vibrations occurring at 918e
900 cmꢀ1 in the free ligands were shifted to higher frequencies
996e937 cmꢀ1 in the chelated one, thus excluding the coordination
via the nitrogen atom [47]. The above statements were further
supported by the occurrence of the stretching modes for (SneC)
and (SneO) in the triorganotin(IV) complexes, assigned in the
range 698e507 and 444e416 cmꢀ1 respectively [48,49].
NMR spectroscopy
1H NMR spectra of the free ligands and their organotin(IV)
complexes have been recorded in DMSO and CDCl3 solution and
tetramethylsilane as internal standard at room temperature. The 1H
NMR spectra of the free ligands show a signal at 10.60e8.74 ppm
Fig. 3. Thermal ellipsoidal plot of C27H25NO3Sn. Displacement ellipsoids are drawn at
the 50% probability level, and H atoms are shown as spheres of arbitrary radii.

30
N. Khan et al. / Journal of Organometallic Chemistry 763-764 (2014) 26e33
Table 1
Experimental data for crystallographic analysis for complexes 1, 2, 3 and 4.
Compounds
1
2
3
4
Gross formula
M
C26H22INO2Sn
626.04
Orthorhombic
P2(1)2(1)2(1)
Plate
Colorless
9.0202(2)
10.0487(2)
26.1695(6)
90.00
90.00
90.00
2372.04(9)
4
1.753
C52H44N4O8Sn2
1090.29
Triclinic
P-1
C27H25NO3Sn
530.17
Orthorhombic
P2(1)2(1)2(1)
Plate
Colorless
9.25010(10)
9.93270(10)
26.0388(4)
90.0
90.00
90.00
2392.40(5)
4
1.472
C26H22BrNO2Sn
579.05
Monoclinic
P2(1)/c
Block
Colorless
11.49820(10)
11.36120(10)
17.6842(2)
90.0
91.1800(10)
90.00
2309.66(4)
4
1.665
1144
Crystal system
Space group
Crystal shape
Color
Block
Yellow
14.642(16)
11.506(13)
14.988(17)
90.00
105.199(18)
90.00
2437(5)
2
ꢀ
a, A
ꢀ
b, A
ꢀ
c, A
ꢁ
ꢁ
ꢁ
a
,
b
,
g
,
3
ꢀ
V, A
Z
Dcalc, (mg/m3)
F(000)
1.486
1096
1.082
1216
2.401
1072
1.096
m
(mmꢀ1
)
2.859
T, K
100
296
296
100
Crystal size, mm
Tmin
Tmax
Measured reflections
Independent reflections
0.32, 0.23, 0.06
0.5138
0.8693
21,743
5293
0.40, 0.30, 0.20
0.5567
0.7457
16,037
5040
0.23, 0.18, 0.03
0.7867
0.9679
22,767
5487
0.36, 0.14, 0.05
0.5652
0.7457
21,575
5288
Reflections with I > 2
s
(I)
5193
2910
5344
4584
Rint
qmax
0.0231
25.50
0.0762
26.50
0.0228
27.50
0.0242
27.50
qmin
2.17
2.26
1.56
2.13
Completeness to theta
1
0.994
0.999
1
h
k
l
ꢀ11 11
ꢀ12 12
ꢀ33 33
0.0488
0.1129
1.061
ꢀ16 18
ꢀ14 12
ꢀ18 18
0.0488
0.1371
0.961
ꢀ11 12
ꢀ12 12
ꢀ32 33
0.0180
0.0446
1.107
ꢀ14 14
ꢀ14 14
ꢀ22 22
0.0218
0.0470
1.034
R[F2 > 2
wR(F2)
S
s
(F2)]
Reflections
Parameters
Restraints
5293
281
0
5.089
ꢀ4.180
5040
299
0
0.618
ꢀ1.092
5487
291
0
0.485
ꢀ0.440
5288
281
0
0.442
ꢀ0.302
ꢀꢀ3
Drmax e A
ꢀꢀ3
Drmin e A
w ¼ 1/[
w ¼ 1/[
w ¼ 1/[
w ¼ 1/[
s
s
s
s
2(F2o)þ(0.0262P)2 þ 28.9017P] where P ¼ (Fo2 þ 2F2c)/3 for compound (1).
2(F2o)þ(0.0950P)2 þ 0.0000P] where P ¼ (Fo2 þ 2F2c)/3 for compound (2).
2(F2o)þ(0.0222P)2 þ 1.4354P] where P ¼ (Fo2þ2F2c)/3 for compound (3).
2(F2o)þ(0.0205P)2 þ 1.1216P] where P ¼ (Fo2 þ 2F2c)/3 for compound (4).
which is due to intramolecularly hydrogen bonded hydroxyl pro-
ton, which completely disappeared in the spectra of the complexes
indicating, thereby, the substitution of the hydroxyl proton and the
chelation of the oxygen to the tin atom, thus showing consistency
with the IR data. The proton signals appearing in the region 3.23e
3.37 ppm were attributed to methyl protons attached to the ni-
trogen atom in complexes (1e4), which remained unchanged on
chelation, supporting further, the non-involvement of this group in
complexation. In complexes (3) and (5), the proton absorptions
appeared as a singlet in the region 3.80 ppm were attributed to the
methoxy protons and in complex (6), the singlet appeared in the
range 2.08 ppm was allotted to the tolyl protons. A multiplet found
at 6.66e8.23 ppm is assigned to the aromatic protons of the free
ligands and all complexes. The individual resonances for the
hydroxamate fragment and phenyl rings were assigned and the
coupling constant values are calculated. In some cases, a more
complex multiplet was found for the aromatic protons, which is
due to the overlapping of the signals of the aromatic protons of the
ligands and phenyl group protons in triphenyltin(IV) complexes
[50,51].
X
R
Cl
C
HO
R
O
O
MeOH/THF
Reflux
N
N
C
HL + Ph3SnCl
Sn
KCl
C
O
O
NaHCO3
RNHOH
2HCl
MeOH/ Ether
X
X
X = I, NO2, OCH3 and Br. R= -CH3, -C6H5 and –C6H4-CH3.
Scheme 1. Synthesis of hydroxamic acid ligands (1e6).
X = I, NO2, OCH3 and Br. R= -CH3, -C6H5 and –C6H4-CH3.
Scheme 2. Synthesis of triphenyltin(IV) complexes (1e6).

N. Khan et al. / Journal of Organometallic Chemistry 763-764 (2014) 26e33
31
Table 2
Selected bond lengths (A) for complexes 1, 2, 3 and 4.
ꢀ
1
2
3
4
I1 C21
2.109(12)
2.086(5)
2.138(7)
2.143(7)
2.162(7)
2.319(5)
1.376(8)
1.262(9)
1.307(10)
1.447(10)
Sn1 O1
Sn1 C13
Sn1 C1
Sn1 C7
Sn1 O2
N1 C19
N1 O1
N1 C26
N2 O3
N2 C21
O2 C19
2.085(5)
2.140(8)
2.154(8)
2.161(6)
2.344(5)
1.309(7)
1.373(6)
1.433(8)
1.154(10)
1.467(11)
1.264(7)
Sn1 O1
Sn1 C1
Sn1 C13
Sn1 C7
Sn1 O2
N1 C19
N1 O1
N1 C27
O2 C19
O3 C21
O3 C26
2.0937(15)
2.143(2)
2.145(2)
2.168(2)
2.3015(16)
1.315(3)
1.377(2)
1.446(3)
1.257(3)
1.365(4)
1.428(3)
Sn1 O1
Sn1 C1
Sn1 C13
Sn1 C7
Sn1 O2
Br1 C21
O1 N1
O2 C19
N1 C19
N1 C26
2.1126(13)
2.142(2)
2.149(2)
2.1667(19)
2.2820(13)
1.9011(19)
1.380(2)
1.265(2)
1.313(2)
1.451(2)
Sn1 O1
Sn1 C13
Sn1 C1
Sn1 C7
Sn1 O2
O1 N1
O2 C19
N1 C19
N1 C26
13CNMR spectra of the free ligands and their organotin(IV)
complexes have been recorded in DMSO solution and tetrame-
thylsilane as internal standard at room temperature. 13C NMR
chemical shifts in every complex show expected resonances and
the spectra are generally in agreement with the results drawn from
1H NMR signals. The carbonyl (C]O) signal appeared at 158.05e
166.02 ppm in free ligands were shifted upfield in the complexes
149.34e161.09 ppm. The methyl carbon attached to the nitrogen
appeared at 38.37e40.98 ppm in complexes (1e4). The methoxy-
and tolyl-carbon appeared at 56.18 and 22.02 ppm in complexes (5)
and (6) respectively. The aromatic carbon C(9) of the phenyl ring
directly attached to the electronegative nitrogen atom appeared at
131.67 ppm, and other carbon atoms in the phenyl ring, C(10)/C(12)
and C(11)/C(13) appeared at 130.34 and 129.44 ppm respectively
and each pair has approximately twice the intensity of those from
the other carbon nuclei. The signal at 127.84 ppm may be assigned
to carbon C(12) of the phenyl moiety. The resonance for aromatic
carbon C(8) of the tolyl ring directly attached to the electronegative
nitrogen atom appeared at 136.89 and C(11) appeared at
128.67 ppm, and other carbon atoms of the tolyl moiety, C(9)/C(11)
and C(10)/C(12) appeared at 132.21 and 129.35 ppm. The signals
appearing at 94.02e156.12 ppm, were assigned to the aromatic
carbons of the hydroxamate moiety and the phenyl rings.
Furthermore, the individual resonances were assigned and the
coupling constants values are calculated. By comparing the 13C
NMR spectra of the free ligands with respective triorganotin(IV)
complexes, a slight upfield shift has been observed in the position
of carbonyl signal, suggesting the bidentate nature of hydroxamate
group [52,53].
The 119Sn NMR spectra of compounds studied herein in DMSO,
at room temperature shows only one sharp signal in the range ꢀ147
to ꢀ261 ppm. The chemical shifts
d(
119Sn) for triphenyltin(IV)
complexes lie in a broad range from ꢀ40 to ꢀ260 ppm [54]. In all
cases of triphenyltin complexes (1e6), the occurrence of 119Sn
chemical shifts in these areas strongly supports the five coordina-
tion around tin in a distorted bipyramidal geometry [55,56].
Single crystal X-ray diffraction studies
The molecular structures of complexes (1e4) are shown in
Figs. 1e4 respectively. Selected bond lengths and angles of com-
plexes (1e4) are listed in Tables 2 and 3. The molecular structures of
complexes 1, 2, 3 and 4 have similar structural features in which the
tin atom is coordinated to two oxygen atoms of the ligand and three
carbon atoms of the phenyl groups, giving rise to a five-coordinated
tin structure. The benzohydroxamic acid moiety acts as a bidentate
ligand and coordinated to the tin atoms via the hydroxyl and
carbonyl oxygen atoms. The bond lengths of Sn(1)eO(1), Sn(1)e
ꢀ
ꢀ
ꢀ
O(2) are 2.086(5) A, and 2.319(5) A for compound (1), 2.085(5) A
ꢀ
ꢀ
ꢀ
and 2.344(5) A for compound (2), 2.0937(15) A and 2.3015(16) A for
Table 3
Selected bond angles (ꢁ) for complexes 1, 2, 3 and 4.
1
2
3
4
O1 Sn1 C13
O1 Sn1 C1
C13 Sn1 C1
O1 Sn1 C7
C13 Sn1 C7
C1 Sn1 C7
O1 Sn1 O2
C13 Sn1 O2
C1 Sn1 O2
C7 Sn1 O2
N1 O1 Sn1
C19 O2 Sn1
C19 N1 O1
C19 N1 C26
O1 N1 C26
O2 C19 N1
O2 C19 C20
C18 C13 Sn1
C14 C13 Sn1
C8 C7 Sn1
C12 C7 Sn1
C2 C1 Sn1
C6 C1 Sn1
120.5(2)
114.5(2)
117.8(3)
88.2(2)
106.5(3)
101.7(3)
71.56(19)
86.1(2)
O1 Sn1 C13
O1 Sn1 C1
C13 Sn1 C1
O1 Sn1 C7
C13 Sn1 C7
C1 Sn1 C7
O1 Sn1 O2
C13 Sn1 O2
C1 Sn1 O2
C7 Sn1 O2
C19 N1 O1
O1 N1 C26
O3 N2 O4
O4 N2 C21
C19 O2 Sn1
N1 O1 Sn1
C6 C1 Sn1
C2 C1 Sn1
C8 C7 Sn1
C12 C7 Sn1
C18 C13 Sn1
C14 C13 Sn1
O2 C19 N1
115.3(2)
116.8(2)
120.4(3)
88.0(2)
103.5(3)
105.0(3)
71.42(17)
84.9(2)
O1 Sn1 C1
O1 Sn1 C13
C1 Sn1 C13
O1 Sn1 C7
C1 Sn1 C7
C13 Sn1 C7
O1 Sn1 O2
C1 Sn1 O2
C13 Sn1 O2
C7 Sn1 O2
C19 N1 O1
C19 N1 C27
O1 N1 C27
N1 O1 Sn1
C19 O2 Sn1
C2 C1 Sn1
C6 C1 Sn1
C14 C13 Sn1
C18 C13 Sn1
C8 C7 Sn1
C12 C7 Sn1
O2 C19 N1
116.34(8)
121.73(7)
115.49(8)
87.84(7)
101.41(8)
106.22(9)
72.04(6)
85.66(7)
87.28(7)
159.70(7)
117.89(19)
128.8(2)
113.27(18)
115.86(12)
111.93(15)
119.23(17)
122.04(17)
119.89(17)
121.71(17)
118.20(17)
124.14(17)
120.0(2)
O1 Sn1 C1
O1 Sn1 C13
C1 Sn1 C13
O1 Sn1 C7
C1 Sn1 C7
C13 Sn1 C7
O1 Sn1 O2
C1 Sn1 O2
C13 Sn1 O2
C7 Sn1 O2
N1 O1 Sn1
C19 O2 Sn1
C19 N1 O1
O1 N1 C26
C6 C1 Sn1
C2 C1 Sn1
C12 C7 Sn1
C8 C7 Sn1
C14 C13 Sn1
C18 C13 Sn1
O2 C19 N1
N1 C19 C20
C20 C21 Br1
107.65(7)
127.49(6)
117.36(7)
88.45(6)
106.73(8)
102.43(8)
71.92(5)
89.92(7)
82.17(6)
85.6(2)
86.0(2)
159.7(2)
117.6(4)
112.6(5)
117.8(6)
128.8(7)
113.4(6)
120.0(7)
119.6(7)
119.6(6)
121.5(5)
118.5(6)
124.0(5)
119.8(5)
122.3(6)
159.4(2)
118.6(5)
114.1(5)
123.6(10)
117.0(9)
112.3(4)
117.9(3)
117.9(7)
124.2(6)
123.9(6)
118.5(5)
121.8(5)
122.4(6)
119.7(5)
157.57(6)
116.20(10)
113.62(12)
117.67(16)
113.52(15)
122.66(16)
119.36(16)
117.66(15)
124.59(15)
119.50(15)
122.68(14)
119.76(17)
121.82(17)
120.01(14)

32
N. Khan et al. / Journal of Organometallic Chemistry 763-764 (2014) 26e33
110
100
90
80
70
60
50
40
30
20
10
0
110
100
(2) Vs K562
90
(3) Vs K562
(3) Vs Jurkat
(3) Vs HepG2
(3) Vs L929
(2) Vs Jurkat
80
(2) Vs HepG2
70
(2) Vs L929
60
50
40
30
20
10
0
0
5 10 15 20 25 30 35 40 45 50 55
0
5 10 15 20 25 30 35 40 45 50 55
Conc.μM
Conc. μM
110
100
90
80
70
60
50
40
30
20
10
0
110
100
90
80
70
60
50
40
30
20
10
0
(6) Vs K52
(5) Vs K562
(5) Vs Jurkat
(5) Vs HepG2
(5) Vs L929
(6) Vs Jurkat
(6) Vs HepG2
(6) Vs L929
0
5 10 15 20 25 30 35 40 45 50 55
0
5 10 15 20 25 30 35 40 45 50 55
Conc. μM
Conc. μM
Fig. 5. Representative graphs show viability of K-562, Jurkat, HepG2 and L929 cells grown for 24 h in the presence of increasing concentrations of the studied triorganotin
complexes (2, 3, 5 and 6).
ꢀ
ꢀ
compound (3) and 2.1126(13) A and 2.2820(13) A for compound (4),
which were found in agreement to the corresponding bond length
of similar compounds in the literature [14,57]. The shorter bond
length is closed to the sum of covalent radii of tin and oxygen
percentage of cell viability in the presence of the studied com-
pounds at M. The four different tested triorganotin(IV) com-
pounds induced concentration-dependent anti-proliferative
effect towards K-562, Jurkat, HepG2 and L929 cells upon treatment
for 24 h. Moreover, the results have shown that these compounds
are more potent towards the suspension cells (K-562 and Jurkat).
All the triphenyltin(IV) compounds were found to have relatively
some promising potency against a range of cells with the inhibitory
m
a
ꢀ
(2.098(6) A) and the longer SneO bond length is much shorter than
ꢀ
the van der Waals radii (4.0 A). The cis-trigonal bipyramid envi-
ronment around tin in compound (1) is defined by the C7 and O2 in
the apical position and O1, C1 and C13 in the equatorial position.
The apical angles C7eSn1eO2 for the four complexes are 159.73ꢁ,
159.42ꢁ, 159.70ꢁ and 157.57ꢁ respectively. The sum of equatorial
angles, C1eSn1eC13, O1eSn1eC13 and O1eSn1eC1 for the four
complexes are 352.80ꢁ, 352.61ꢁ, 353.56ꢁ and 352.50ꢁ respectively.
These data indicated that there is severe distortion from the ideal
trigonal bipyramidal geometry found in all the four complexes. It
was also noted that there is no significant hydrogen bonding
interaction in the four molecular structures.
concentration IC50 values of 2.50
for complex (2), 2.20, 3.00, 4.20, 4.00 for complex (3), 2.20, 3.00,
3.60, 6.00 M for complex (5) and 3.10, 3.20, 4.00, 3.80 M for
mM, 2.30 mM, 3.05 mM and 4.10 mM
m
m
complex (6) as presented in Table 4. In all cases, the triphenyltin(IV)
complexes were found even more effective than doxorubicin.
Doxorubicin is commonly used to treat leukemias as well as other
types of cancer, was employed as a positive control. Our current
data are in agreement with previous study, whereby organotin(IV),
especially triorganotin compounds showed antiproliferative effects
in various cancer cell lines [56,58]. The triphenyltin(IV) complexes
exhibit higher antiproliferative effects compare to diorganotin(IV)
derivatives against different cell lines [59e62]. Therefore, on the
basis of the IC50 values, triphenyltin(IV) complexes exerted higher
cytotoxic activity and has the potential to be developed as an
antitumor agent due to the potent cytotoxic effect at micro molar
concentration which warrant further mechanistic studies.
In vitro cytotoxic activity
The synthesized triphenyltin(IV) hydroxamates were evaluated
for the biological activity specifically cytotoxicity on four different
cell lines K-562, Jurkat, HepG2 and L929. Fig. 5 presents the
Table 4
The experimental antiproliferative activity IC50 values of triorganotin(IV) complexes
against K-562, Jurkat, HepG2 and L929 cells.
Conclusions
Compounds
IC50 (mM)
In conclusion, by using suitable experimental conditions, we
have successfully synthesized six new triphenyltin(IV) hydrox-
amates, which gave fairly sharp melting points indicating that the
compounds were pure and characterized by elemental analyses, IR,
TGA, NMR and X-ray single-crystal diffraction. The structural ana-
lyses of complexes (1e6) reveal that the coordination mode
K-562
Jurkat
HepG2
L929
Ph3SnONCH3C(O)C6H4NO2-2 (2)
Ph3SnONCH3C(O)C6H4OCH3-2 (3)
Ph3SnONC6H5C(O)C6H4OCH3-2 (5)
Ph3ONCH3C6H4C(O)C6H4NO2-2 (6)
2.50
2.20
2.20
3.10
2.30
3.00
3.00
3.20
3.05
4.20
3.60
4.00
4.10
4.00
6.00
3.80

N. Khan et al. / Journal of Organometallic Chemistry 763-764 (2014) 26e33
33
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Acknowledgments
This work was supported by grant UKM-ST-06-FRGS 112-2009,
UKM-GUP-NBT-08-27-112 and GUP-2012-022 and we gratefully
acknowledge the School of Chemical Sciences and Food Technology,
Universiti Kebangsaan Malaysia, for providing the essential labo-
ratory facilities. We would also like to thank the Faculty Develop-
ment Programme, University of Balochistan Quetta, Pakistan for
their financial support.
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