Synthesis, characterization, crystal structure and antitumor activity of organotin(IV) compounds bearing ferrocenecarboxylic acid

Article abstract of DOI:10.1016/j.ica.2011.04.049

Four new organotin(IV) complexes [(Bu₃Sn)(FcCOO)]_n (1), [(μ-Bu₂Sn)₂(μ-Bu₂SnFcCOO) ₂(μ₃-O)₂(μ-OCH₃) ₂]₂ (2), [Ph₃Sn(FcCOO)(H

Full text of DOI:10.1016/j.ica.2011.04.049

Inorganica Chimica Acta 375 (2011) 150–157
Contents lists available at ScienceDirect
Inorganica Chimica Acta
journal homepage: www.elsevier.com/locate/ica
Synthesis, characterization, crystal structure and antitumor activity
of organotin(IV) compounds bearing ferrocenecarboxylic acid
⇑
⇑
Chengchen Zhu, Liguo Yang, Dacheng Li, Qingfu Zhang , Jianmin Dou , Daqi Wang
School of Chemistry and Chemical Engineering, Liaocheng University, Liaocheng 252059, PR China
a r t i c l e i n f o
a b s t r a c t
Article history:
Four new organotin(IV) complexes [(Bu3Sn)(FcCOO)]n (1), [(l-Bu2Sn)2(l-Bu2SnFcCOO)2(l3-O)2-
(
(
l
-OCH3)2]2 (2), [Ph3Sn(FcCOO)(H2O)](phen) (3) and [{Ph3Sn(FcCOO)}2(4,40-bipy)] (4) [Fc =
Received 25 November 2010
Received in revised form 26 April 2011
Accepted 30 April 2011
g
5-C5H5)Fe( 5-C5H4)] have been synthesized and characterized by elemental analyses, IR, (1H and
g
13C) NMR spectra and X-ray single-crystal diffraction analyses. The structure analyses show that all tin
atoms in complexes 1–4 are five-coordinated with trigonal bipyramid geometry. Complexes 1–4 and
FcCOOH undergo reversible one-electron oxidations in methanol solution. The antitumor activities of
complexes 1–4 have also been tested. Complexes 1 and 2 exhibit medium activity towards P388 cell lines
and Hela cell lines. Complexes 3 and 4 exhibit medium activity towards P388 cell lines but strong activity
towards Hela cell lines. This may result from complexes 3 and 4 including the neutral molecules 1,10-
phenanthroline and 4,40-bipy.
Available online 11 May 2011
Keywords:
Organotin(IV)
Ferrocenecarboxylic acid
Antitumor activity
Crown Copyright Ó 2011 Published by Elsevier B.V. All rights reserved.
1. Introduction
steric hindrance of ferrocenyl. Till now, only several organotin
complexes containing FcCOO group have been structurally charac-
In recent years, organotin(IV) compounds have attracted more
attention, not only for their potential antitumour activities
[1–10], but also for their versatile structures in solid and solution,
such as monomers, dimers, tetramers, oligomeric ladders and
hexameric drums and so on [11]. In our previous work, several
12-MC-4 organotin metallacrowns with salicylhydroxamic acid
ligand have been successfully designed and prepared [12,13].
Since ferrocene was synthesized by Kealy and Pauson [14], great
attention has been paid to the metal complexes containing ferroce-
nyl ligands. Ferrocenecarboxylic acid is the simplest carboxylic
acid containing ferrocene group, It has attracted much attention
in the field of coordination chemistry [15] due to its excellent
properties such as high thermal stability, excellent redox activity
and potential applications in catalysis, magnetism and non-linear
optics [16–22]. As a ligand containing typical organometallic
group, ferrocenecarboxylic acid has versatile coordination modes,
such as monodentate, bidentate bridging, bidentate chelating,
and tridentate-bridging (Scheme 1) [23]. Up to now, a large num-
ber of transition-metal complexes containing ferrocenecarboxylic
acid have been synthesized and characterized [24–30].
terized by X-ray crystallography, such as FcCOOSn(CH@CH2)3 [31],
[FcCOOSnBu2O]2ꢀ4C6H6 [32], [n-BuSnCl(FcCOO)]3(O)(OH) [33],
[{BuSn(O) FcCOO}6] [34], {[l-(n-Bu)2Sn(l-FcCOO(n-Bu)2Sn(l3-O)]-
FcCOO}[35], [Me3Sn(Fc COO)]n, [Bn3Sn(FcCOO)], [BnSn(O)-
(FcCOO)]6, [Me2Sn(FcCOO)2] [36], and [(n-Bu)2Sn (FcCOO)2]2 [37].
In this report, four new organotin(IV) complexes with ferrocene-
carboxylic acid, [(Bu3Sn)(FcCOO)]n (1), [(
l-Bu2Sn)2(l-Bu2SnFc-
COO)2 3-O)2( -OCH3)2]2 (2), [Ph3Sn(FcCOO)(H2O)](phen) (3),
(l
l
and [{Ph3Sn(FcCOO)}2 (4,40-bipy)] (4) were successfully prepared
and characterized by elementary analyses, FT-IR spectroscopy,
NMR spectroscopy and single crystal X-ray diffraction. The
in vitro tumor-inhibiting activities of the four complexes against
P388 cell lines and Hela cell lines are also investigated.
2. Experimental
2.1. Material and methods
All reagents were obtained from commercially available sources
and were used without further purification. IR spectra were re-
corded on a Nicole-5700 spectrophotometer sodium chloride op-
tics using KBr disks. 1H and 13C NMR spectra were recorded on
Varian Mercury Plus 400 spectrometer operating at 400 and
100.6, respectively. The spectra were acquired at 298 K. 13C spectra
are broadband proton decoupled. Elemental analyses were
performed with a PE-2400II apparatus.
However, it is still a big challenge for the preparation of organo-
tin complexes bearing ferrocenecarboxylic groups because of the
⇑
Corresponding authors. Tel.: +86 0635 8239298; fax: +86 635 8239001.
E-mail addresses: zhangqingfu@lcu.edu.cn (Q. Zhang), dougroup@163.com
(J. Dou).
0020-1693/$ - see front matter Crown Copyright Ó 2011 Published by Elsevier B.V. All rights reserved.
doi:10.1016/j.ica.2011.04.049

C. Zhu et al. / Inorganica Chimica Acta 375 (2011) 150–157
151
O
O
M
(0.065 g, 0.2 mmol). Yield: 34 mg (46%). Anal. Calc. for
56H96Fe2O8Sn4: C, 45.32; H, 6.52. Found: C, 45.01; H, 6.85%. IR
(KBr)/cmꢁ1
3373(w), 2956(s), 2857(m), 1580(m), 1463(m),
1381(m), 1332(m), 1180(m), 817(m), 795(m), 681(m), 612(m),
560(m), 483(m). 1H NMR: d 0.91–1.63 (m, 108H, n-Bu–H), 3.48 (s,
12H, CH3O), 4.17 (s 20H Cp-H), 4.33 (d 8H Cp-H), 4.76 (d, 8H, Cp-
H). 13C NMR: d 13.66 (CH3), 26.75, 27.06 (SnCH2CH2CH2), 27.30,
27.88, (SnCH2CH2CH2), 69.60 (s 20C C5H5–C), 70.69 (d 8C C5H4–C),
70.75 (d 8C C5H4–C), 73.13 (s 4C Cp-Cipso), 176.69, (COO).
O
M
C
C
R
R
C
:
M
O
M
M
O
O
O
O
O
O
C
C
R
R
C
M
M
R
M
M
2.2.3. Preparation of [Ph3Sn(FcCOO)(H2O)](phen) (3)
Ph3SnCl (0.077 g, 0.2 mmol) was added to a solution of FcCOOH
(0.046 g, 0.2 mmol) and (CH3)4NOH (0.073 g, 0.2 mmol) in metha-
nol (10 mL), the mixture solution was stirred 30 min, then 1,10-
phen (0.036 g, 0.2 mmol) was added to the solution and stirred
overnight at room temperature in air. Then the above solution
was filtered. The filtrate was allowed to stand at room temperature
for about three weeks. Yellow crystal suitable for X-ray diffraction
analysis was obtained. Yield: 105 mg (68%). Anal. Calc. for C41H34Fe-
N2O3Sn: C, 63.35; H, 4.41; N, 3.60. Found: C, 62.57; H, 4.27; N, 3.78%.
IR (KBr)/cmꢁ1: 3055(w), 1628(s), 1587(m), 1567(m), 1509(m),
1454(m), 1422(m), 1316(m), 1173(m), 845(m), 732(m), 699(m),
513(m), 485(m), 455(w). 1H NMR: d 1.87 (s, 2H, H2O), 3.99 (s 5H
Cp-H), 4.34 (d 2H Cp-H) 4.83 (d, 2H, Cp-H), 7.25–8.23, (m, 23H,
Ph-H and phen-H). 13C NMR: d 69.62(s 5C C5H5–C), 70.72 (d 2C
C5H4–C), 70.98 (d 2C C5H4–C), 71.27 (s 1C Cp-Cipso), 122.96,
128.50, 128.81, 129.12, 130.02, 136.66, 137.13, 146.21, 150.22,
(Ph-C and 1,100-phen-C), 178.33, (COO).
Scheme 1. Typical coordination modes for the ferrocenecarboxylate ligand
[R = (
5-C5H5)Fe( 5-C5H4)].
g
g
2.2. Syntheses
2.2.1. Preparation of [(Bu3Sn)(FcCOO)]n (1)
Bu3SnCl (0.065 g, 0.2 mmol) was added to a solution of FcCOOH
(0.046 g, 0.2 mmol) and (CH3)4NOH (0.073 g, 0.2 mmol) in metha-
nol (10 mL). The mixture solution was stirred overnight at room
temperature in air. Then the above solution was filtered. The fil-
trate was allowed to stand at room temperature for about three
weeks. Finally, red crystal suitable for X-ray diffraction analysis
was obtained. Yield: 63 mg (61%). Anal. Calc. for C23H36FeO2Sn: C,
53.21; H, 6.99. Found: C, 53.45; H, 6.41%. IR (KBr)/cmꢁ1: 3430(s),
2955(m), 2921(m), 1578(s), 1557(s), 1459(s), 1383(s), 1355(m),
1337(m), 669(m), 603(m), 509(s), 481(m). 1H NMR: d 0.91–1.67
(m, 54H, n-Bu–H), 4.17 (s 10H Cp-H), 4.32 (d 4H Cp-H), 4.76 (d,
4H, Cp-H). 13C NMR: d 13.66 (CH3), 26.75, 27.06, 27.38, 27.9,
(SnCH2CH2CH2), 69.60 (s 10C C5H5–C), 70.69 (d 4C C5H4–C),
70.75 (d 4C C5H4–C), 73.15 (s 2C Cp-Cipso), 176.83, (COO).
2.2.4. Preparation of [{Ph3Sn(FcCOO)}2(4,40-bipy)] (4)
The procedure was the same as that for (3), except that 4,40-bipy
(0.016 g, 0.1 mmol) was used instead of 1,10-phen (0.036 g,
0.2 mmol). Yield: 71 mg (54%). Anal. Calc. for C68H56Fe2N2O4Sn2:
C, 62.14; H, 4.29; N, 2.13. Found: C, 61.54; H, 4.12; N, 2.10%. IR
2.2.2. Preparation of [(l-Bu2Sn)2(l-Bu2SnFcCOO)2(l3-O)2(l-OCH3)2]2
(2)
The procedure was the same as that for complex 1, except that
(KBr)/cmꢁ1
:
3439(w), 1632(m), 1599(m), 1455(m), 1430(m),
Bu2SnCl2 (0.061 g, 0.2 mmol) was used instead of Bu3SnCl
1376(m), 1310(s), 1172(m), 808(m), 783(m), 696(m), 616(m),
Table 1
Crystal, data collection and structure refinement parameters for complexes 1–4.
Complex 1
23H36FeO2Sn
519.06
298(2)
Complex 2
Complex 3
Complex 4
Empirical formula
Formula weitht
Temperature (K)
k (Å)
C
C111H190Fe4O16Sn8
2953.55
298(2)
C41H34FeN2O3Sn
777.24
298(2)
C68H56Fe2N2O4Sn2
1314.23
298(2)
0.71073
0.71073
0.71073
0.71073
Crystal system
Space group
a (Å)
b (Å)
c (Å)
monoclinic
P2(1)/c
11.9501(17)
10.3200(11)
19.690(2)
90
102.640(2)
90
2369.4(5)
4
triclinic
triclinic
triclinic
ꢀ
ꢀ
ꢀ
P1
P1
P1
11.5591(11)
14.4283(15)
20.494(2)
91.1800(10)
93.9980(10)
102.714(2)
3323.8(6)
9.3277(8)
9.7111(7)
9.9415(9)
12.1722(12)
15.5537(16)
106.399(2)
91.4220(10)
92.3560(10)
1691.5(3)
16.4615(13)
82.6450(10)
84.078(2)
65.0790(10)
1427.3(2)
a
(°)
b (°)
c
(°)
V (Å3)
Z
1
2
1
Absorption coefficient (mmꢁ1
)
1.680
1.455
1064
1.948
1.476
1488
1.210
1.526
788
1.414
1.529
662
Dcalc (mg mꢁ3
F(0 0 0)
)
Crystal size (mm)
0.39 ꢂ 0.14 ꢂ 0.07
1.75–25.01
ꢁ14 6 h 6 9, ꢁ12 6 k 6 12,
ꢁ23 6 l 6 23
4123
0.46 ꢂ 0.44 ꢂ 0.43
1.45–25.02
ꢁ13 6 h 6 12, ꢁ14 6 k 6 17,
ꢁ22 6 l 6 24
11 148
0.43 ꢂ 0.39 ꢂ 0.27
1.75–25.01
ꢁ11 6 h 6 11, ꢁ14 6 k 6 11,
ꢁ18 6 l 6 17
8886
0.43 ꢂ 0.41 ꢂ 0.36
2.27–25.02
ꢁ11 6 h 6 10, ꢁ11 6 k 6 11,
ꢁ14 6 l 6 19
7464
H
Range (°)
Limiting indices
Independent reflection
Maximum and minimum
transmission
0.7519, 0.7192
0.4880, 0.4677
0.7360, 0.6243
0.6300, 0.5815
Goodness-of-fit (GOF) on F2
1.016
1.029
1.000
1.031
R[I > 2
R (all data)
r
(I)]
R1 = 0.0670, wR2 = 0.1664
R1 = 0.1140, wR2 = 0.2038
R1 = 0.0789, wR2 = 0.1828
R1 = 0.1829, wR2 = 0.2575
1.135, ꢁ0.577
R1 = 0.0416, wR2 = 0.0870
R1 = 0.0683, wR2 = 0.1030
0.848, ꢁ0.540
R1 = 0.0603, wR2 = 0.1344
R1 = 0.0975, wR2 = 0.1591
0.913, ꢁ0.641
Largest difference in peak and hole 0.993, ꢁ0.616
(ꢂ102 e Åꢁ3
)

152
C. Zhu et al. / Inorganica Chimica Acta 375 (2011) 150–157
582(w), 510(m), 484(m), 455(m), 448(m). 1H NMR: d 3.99 (s, 10H,
Cp-H), 4.35 (d, 4H, Cp-H), 4.83 (d, 4H, Cp-H), 7.25-8.23, 8.71, 8.73,
(m, 38H, Ph-H and 4,40-bipy-H). 13C NMR: d 69.66 (s 10C C5H5–C),
70.83 (d 4C C5H4–C), 71.02 (d 4C C5H4–C), 71.29 (s 2C Cp-Cipso),
128–137, (Ph-C), 121.38, 145.54, 150.60, (4,40-bipy-C), 178.34,
(COO).
for 20 min on a plate shaker to ensure complete dissolution. The
optical density of each well was measured at 570 nm wavelength.
The antitumor activity was determined three times in independent
experiments.
3. Results and discussion
3.1. Syntheses
2.3. X-ray crystallography
Complexes 1 and 2 were obtained by the reactions of ferrocene-
carboxylic acid with Bu3SnCl and Bu2SnCl2 in methanol solution,
respectively. Complexes 3 and 4 were also obtained in methanol
solution but using Ph3SnCl, FcCOOH and neutral ligand 1,10-phe-
nanthroline, 4,40-bipy as starting materials, respectively. As shown
in Scheme 2, all the reactions occurred at the basic conditions.
Crystal data are given in Table 1, together with refinement de-
tails. All X-ray crystallographic data were collected on a Bruker
SMART CCD 1000 diffractometer with graphite monochromated
Mo Ka radiation (k = 0.71073 Å) at 298(2) K. A semi-empirical
absorption correction was applied to the data. The structure was
solved by direct methods using SHELXL-97 and refined against F2
by full-matrix least squares using SHELXL-97. Hydrogen atoms were
placed in calculated positions.
3.2. IR spectra
In compound 1, there are three disordered butyl groups. In the
first butyl group, the C13–C15 atoms were distributed two posi-
tions with refined site occupancies of 0.724(16) and 0.276(16). In
the second butyl group, the C17–C19 atoms were distributed two
positions with refined site occupancies of 0.602(12) and
0.398(12). In the third butyl group, the C21–C23 atoms were dis-
tributed two positions with refined site occupancies of 0.701(12)
and 0.299(12). Similarly, in compound 2, the disordered butyl car-
bon atoms C13–C15, C17–C19, C25–C27, C52–C54 and C42 were
also distributed two positions with refined site occupancies of
0.60(2) and 0.40(2), 0.629(15) and 0.371(15), 0.458(17) and
0.542(17), 0.396(10) and 0.604(10), 0.52(3) and 0.48(3), respec-
tively. In addition, the DELU and SIMU restraints were applied to
C10 and C11 atoms in compound 4.
The IR spectra of complexes 1–4 were recorded in the range of
4000–400 cmꢁ1
.
The band at 2955–2852 cmꢁ1 for 1, 2956–
2857 cmꢁ1 for 2 can be assigned to the sp3 C–H bonds of the butyl
groups. The vibrations of Cp-H are much closer to 3100 cmꢁ1. The
band at 3055 cmꢁ1 for 3, 3065–2987 cmꢁ1 for 4 belongings to C–H
vibration of Cp-H and Ph-H from the Ph3Sn and phen/bpy ligands,
overlapping in the spectrum, which agree well with the previous
report [27,39]. The strong absorption bands at 1578–1599 and
1383–1422 cmꢁ1 ranges can be assigned to the
m
as(COOꢁ) and
m
s(COOꢁ) vibrations. The absorption bands at 1454, 1481 cmꢁ1 in
complex 3 and 1455, 1479 cmꢁ1 in complex 4 can be assigned to
C@N vibration [40,41].
3.3. NMR spectra
2.4. Electrochemistry
The 1H NMR spectra show the expected integration and peak
multiplicities. The 1H NMR spectra of complexes 1 and 2 show that
the chemical shifts of the protons of Cp-ring and butyl bound to tin
atom (CH3CH2CH2CH2Sn) exhibit multi signals at the region 4.17–
4.76 ppm and 0.91–1.67 ppm and there are no peak of the protons
of –COOH, which indicates the oxygen atoms coordinate to the tin
atoms. The 1H NMR spectra of complex 2 exhibits a signal peak of
the protons of methanol at 3.48 ppm, but no peak exhibits the
proton of –OH, which indicates that the methanol was
deprotonated. The protons of aromatic rings exhibit at the region
of 7.2–8.2 ppm.
Cyclic voltammetry studies were conducted by a potentiostat
CHI 1030A (Shanghai Chenhua Instruments Co.). A conventional
three-electrode electrochemical system with Ag/AgCl (in 3 M KCl)
and a platinum wire (0.5 mm in diameter) were used as the refer-
ence and counter electrodes, and a GC as the working electrode,
respectively. For CV, the potential were scanned from 0.1 to 1.3 V
at a scan rate of 50 mV sꢁ1 and the potential referred to the Ag/
AgCl. The measurements were performed in CH3OH solution con-
taining
tetrabutyl
ammonium
perchlorate
(n-Bu4NClO4)
(0.1 mol dmꢁ3) as supporting electrolyte.
In 13C NMR spectra, the positions of Cp-ring signals are almost
identical in the four complexes, at the region of 69.6–73.1 ppm.
The positions of CH3CH2CH2CH2Sn in complex 2 is similar to com-
plex 1 and the positions of aromatic ring carbon signals remains
almost unchanged in complexes 3 and 4. The carbon signals of
–COO appear at 176.83, 176.69, 178.33, 178.34 ppm in complexes
1–4.
2.5. Antitumor activity in vitro
The tumor cell lines which were used for screening were grown
and maintained in RPMI-1640 medium supplemented with 10% fe-
tal bovine serum at 37 °C in humidified incubators in an atmo-
sphere of 5% CO2. Cell proliferation in compound-treated cultures
was evaluated by using a system based on the tetrazolium com-
pound (MTT) [38] in the School of Medicine and Pharmacy, Ocean
University of China. All cell lines were seeded into 96 well plates at
a concentration of about 50,000 cells/mL and were incubated in an
3.4. Electrochemical studies
The electrochemical behaviors of FcCOOH and complexes 1–4
were investigated by cyclic voltammetry. The results were shown
in Fig. 1. It can be seen from Fig. 1 that all compounds show a single
quasireversible peak with an E1/2 value of 0.71 V for FcCOOH,
0.42 V for 1, 0.45 V for 2, 0.52 V for 3, 0.55 V for 4, respectively.
The voltammogram of complexes 1–4 are different from FcCOOH.
The half-wave potential of complexes 1–4 is lower than FcCOOH,
sugesting that these compounds are easier to undergo sequential
oxidation and reduction than FcCOOH. The electrochemical behav-
iors for complexes 1–4 and ferrocenecarboxylic acid are reversible
even after being tested for many cycles. These results suggest that
atmosphere of 5% CO2 for 72 h. Then, 150 lL of the sample
(organotin complexes) DMSO solution was added and further incu-
bation was carried out at 37 °C for 48 h. The compounds were seri-
ally diluted (in four to six steps) with DMSO and added to cell
incubation medium at the final concentration of 1.0% DMSO in
the medium. Fifty microliters of 0.1% MTT was added to each well.
After 4 h incubation, the culture medium was removed, and 150 lL
of isopropanol was added to dissolve the insoluble blue formazan
precipitates produced by MTT reduction. The plate was shaken

C. Zhu et al. / Inorganica Chimica Acta 375 (2011) 150–157
153
Bu
Bu
Sn
Bu
Fc
Bu
Sn
Bu Bu
O
(CH3)4NOH
MeOH
+ Bu3SnCl
FcCOOH
C
O
O
C
Fc
O
n
1
Bu
O
Bu
Fc
Fc
O
C
O
Bu Bu
CH3
Sn
CH3
C
O
Bu
O
O Sn
Bu
O
Bu
Bu
O
Sn
(CH3)4NOH
MeOH
Sn
Bu
Sn Bu
FcCOOH +
Bu2SnCl2
Bu
O
Sn
O
O
Sn
O
CH3
Bu
CH
O
Sn
O
O
Fc
3 Bu
Bu
C
Bu
C
Bu
Fc
O
2
Ph
Ph
O
Sn
O
1,10-phen
Fc
C
N
N
Ph
O
(CH3)4NOH
FcCOOH + Ph3SnCl
3
MeOH
Ph
Ph
4,4'-bipy
Sn
Ph
N
O
O
Fc
C
2
4
Scheme 2. The syntheses procedures of complexes 1–4.
ferrocenecarboxylic acid
2.5
2.0
1.5
1.0
complex 1
0.5
complex 2
complex 3
0.0
complex 4
-0.5
-1.0
-1.5
-2.0
-2.5
-3.0
0.2
0.4
0.6
0.8
1.0
1.2
Potential / V
Fig. 2. Molecular structure of the complex 1.
Fig. 1. The cyclic voltammogram of complexes 1–4 and the ferrocenecarboxylic
acid in methanol containing n-Bu4NClO4 (0.1 M) at a scanning rate of 50 mV sꢁ1 (vs.
Ag/AgCl).
3.5. Description of crystal structures
3.5.1. Crystal structure of complex (1)
the four complexes are stable and does not decompose upon oxida-
tion, which is consistent with the previous report [34].
The molecular structure of complex 1 is shown in Fig. 2. The
selected bond lengths and angles are listed in Table 2. In the

154
C. Zhu et al. / Inorganica Chimica Acta 375 (2011) 150–157
Table 2
bond distances are different [O1–Sn1 2.543(6), O2A–Sn1
Selected bond lengths [Å] and angles [°] for complexes 1–4.
2.117(6) Å]. In the carboxylate groups of complex 1, the C–O bond
distances are 1.218(8) and 1.265(10) Å. Therefore, the C–O and
C@O can be distinguished according the bond lengths of the Sn–
O and C–O, although they are highly delocalized.
Complex 1
Sn(1)–C(20)
Sn(1)–C(12)
Sn(1)–O(2)#1
2.063(9)
2.099(8)
2.117(6)
2.132(11)
121.5(4)
99.1(4)
97.8(3)
118.7(5)
115.8(4)
Sn(1)–O(1)
O(1)–C(1)
O(2)–C(1)
O(2)–Sn(1)#2
C(12)–Sn(1)–O(1)
O(2)#1–Sn(1)–O(1)
C(16)–Sn(1)–O(1)
O(2)#1–Sn(1)–C(16)
C(20)–Sn(1)–O(1)
2.543(6)
1.218(8)
1.265(11)
2.117(6)
82.3(3)
174.3(2)
82.2(3)
92.6(4)
Sn(1)–C(16)
C(20)–Sn(1)–C(12)
C(20)–Sn(1)–O(2)#1
C(12)–Sn(1)–O(2)#1
C(20)–Sn(1)–C(16)
C(12)–Sn(1)–C(16)
3.5.2. Crystal structure of complex (2)
The molecular structure of complex 2 is shown in Fig. 4. The se-
lected bond lengths and angles are listed in Table 2. In the crystal
structure of complex 2, there are two molecules in the asymmetric
unit. Each unit is a ladder-type structural motif with all tin atoms
five coordinated. There was a serious distortion about the coordi-
nation geometry of the tin atoms, but it still can be described as
a distorted trigonal bipyramidal. In this complex, all FcCOO groups
act as monodentate ligand coordinating to tin atoms. The molecule
85.5(3)
Complex 2
Sn(1)–O(3)
Sn(1)–O(4)#1
Sn(2)–O(3)
Sn(3)–O(7)
Sn(3)–O(8)#2
Sn(4)–O(7)#2
O(1)–C(1)
2.014(8)
2.251(8)
2.127(8)
2.010(11)
2.273(10)
2.055(10)
1.297(15)
1.286(19)
71.4(3)
73.6(3)
73.1(3)
70.5(4)
73.7(5)
Sn(1)–O(1)
Sn(2)–O(3)#1
Sn(2)–O(4)
Sn(3)–O(5)
Sn(4)–O(7)
Sn(4)–O(8)
O(2)–C(1)
O(6)–C(28)
O(3)–Sn(1)–O(1)
O(1)–Sn(1)–O(4)#1
O(3)–Sn(2)–O(4)
O(7)–Sn(3)–O(5)
O(5)–Sn(3)–O(8)#2
O(7)#2–Sn(4)–O(8)
2.123(8)
2.044(8)
2.146(8)
2.128(10)
2.098(11)
2.135(11)
1.293(16)
1.220(18)
82.0(3)
153.4(3)
146.7(3)
81.9(4)
152.3(4)
72.6(4)
A and B adopt a centrosymmetric dimeric structure by virtue of l3
-
oxo [Sn2–O3 2.127(8) Å, Sn2–O3a 2.044(8) Å; Sn4–O7 2.098(11) Å,
Sn4–O7a 2.055(10) Å] which form the central Bu4Sn2O2 core with
planar Sn2O2 ring. There are two tridentate oxygen atoms in each
unit which link two endo-cyclic Sn atoms and one exo-cyclic Sn
atom. The distance between the two tin atoms is 3.403 Å
(Sn1ꢀꢀꢀSn2, Sn1aꢀꢀꢀSn2a) and 3.421 Å (Sn3ꢀꢀꢀSn4, Sn3aꢀꢀꢀSn4a) in
the two endo-cyclic. And the distance between the two tin atoms
in the exo-cyclic is 3.340 Å (Sn2ꢀꢀꢀSn2a) and 3.324 Å (Sn4ꢀꢀꢀSn4a),
respectively. The additional links between the endo- and exo-cyclic
Sn are provided by bidentate deprotonated methanol that form the
asymmetrical bridges (Sn1–O4 2.251(8) Å, Sn2–O4 2.146(8) Å;
Sn3–O8 2.273(10) Å, Sn4–O8 2.135(11) Å). The dihedral angle be-
tween the planes of the Sn2O2 rings is 83.36° in this complex.
In complex 2, the molecule A and B are linked via C10–H10ꢀꢀꢀO6
interactions. The complex is linked into one-dimensional infinite
chains via C10A–H10AꢀꢀꢀO6A. The oxygen atoms O6 and O6A derive
from the carboxyl groups in molecule B. Then the 1D chain is self-
assembled into a 2D supramolecular framework (Fig. 5) by C37–
H37ꢀꢀꢀO2 interactions. The oxygen atoms O2 and O2A derived from
the carboxyl groups in molecule A. The distance of H10ꢀꢀꢀO6 and
H10AꢀꢀꢀO6A is 2.42 Å and the distance of H37ꢀꢀꢀO2 is 2.62 Å, which
both lie within the values in previous literature [42,43]. The angle
of C10–H10ꢀꢀꢀO6, C10A–H10AꢀꢀꢀO6A is 169.6° and the angle of C37–
H37ꢀꢀꢀO2 is 151.3°. The information hydrogen bonds were showed
in Table 3.
O(5)–C(28)
O(3)–Sn(1)–O(4)#1
O(3)#1–Sn(2)–O(3)
O(3)#1–Sn(2)–O(4)
O(7)–Sn(3)–O(8)#2
O(7)#2–Sn(4)–O(7)
O(7)–Sn(4)–O(8)
146.2(4)
Complex 3
Sn(1)–C(12)
Sn(1)–C(18)
Sn(1)–O(3)
2.126(4)
2.146(4)
2.405(3)
1.224(5)
121.91(17)
121.65(17)
97.77(15)
87.14(15)
85.02(14)
Sn(1)–C(24)
Sn(1)–O(1)
O(1)–C(1)
2.132(4)
2.152(3)
1.280(5)
O(2)–C(1)
C(12)–Sn(1)–C(24)
C(24)–Sn(1)–C(18)
C(24)–Sn(1)–O(1)
C(12)–Sn(1)–O(3)
C(18)–Sn(1)–O(3)
C(12)–Sn(1)–C(18)
C(12)–Sn(1)–O(1)
C(18)–Sn(1)–O(1)
C(24)–Sn(1)–O(3)
O(1)–Sn(1)–O(3)
114.47(17)
97.93(15)
87.97(14)
83.97(15)
172.60(11)
Complex 4
O(1)–C(1)
Sn(1)–O(2)
Sn(1)–C(24)
O(2)–Sn(1)–C(18)
O(2)–Sn(1)–C(12)
C(18)–Sn(1)–C(12)
1.224(10)
2.094(5)
2.116(8)
101.9(2)
91.0(3)
O(2)–C(1)
Sn(1)–C(18)
Sn(1)–C(12)
O(2)–Sn(1)–C(24)
C(18)–Sn(1)–C(24)
C(24)–Sn(1)–C(12)
1.284(10)
2.106(8)
2.136(8)
95.5(3)
128.5(3)
113.2(3)
114.5(3)
Symmetry transformations used to generate equivalent atoms: (1) #1 ꢁx + 2, y + 1/
2, ꢁz + 1/2 #2 ꢁx + 2, y ꢁ 1/2, ꢁz + 1/2; (2) #1 ꢁx + 1, ꢁy + 1, ꢁz #2 ꢁx, ꢁy, ꢁz + 1;
(4) #1 ꢁx + 1, ꢁy + 2, ꢁz.
crystalline state, this complex adopts an infinite 1D polymeric
chain structure. The tin atoms are arranged in zig-zag chain rather
than colinear (Fig. 3). And each Sn atom in this complex shows
trans-trigonal bipyramidal coordination. The three carbon atoms
occupy the equatorial positions and the two oxygen atoms occupy
the axial positions [O1–Sn1–O2A, 174.3(2)°] for each tin atom. In
the complex, FcCOO groups adopt bidentate bridging coordination
mode that links the tin atoms into a chain. In addition, the Sn–O
3.5.3. Crystal structure of complex (3)
The molecular structure of complex 3 is shown in Fig. 6. The se-
lected bond lengths and angles are given in Table 2. For complex 3,
the geometry at Sn1 is distorted trigonal bipyramidal in which the
axial apical positions were occupied by two oxygen atoms. The
two oxygen atoms come from the water molecular and carboxyl
group, respectively. The four atoms Sn1, C12, C18 and C24 which
form a palne with the tin atom slightly deviate from the ideal plane
by 0.173 Å. The angle of O1–Sn1–O3 is 172.60(11)°. In this complex,
ferrocenecarboxylic acid is monodentate ligand and the distance
between Sn1 and O1 is 2.152(3) Å. The water molecular is also found
in the coordination sphere, with Sn–O bond length is 2.405(3) Å.
As shown in Fig. 7, the adjacent molecules form a linear
1D chain structure by intramolecular C31–H31ꢀꢀꢀO1 and
intermolecular C38–H38ꢀꢀꢀO2 hydrogen bonds in which the oxygen
atoms O1, O2 derived from the carboxyl group. The distance of
C31ꢀꢀꢀO1 and C38ꢀꢀꢀO2 is 3.517(6) and 3.127(7) Å, which both lie
within the values in previous literature [44,45]. These adjacent
1D chains are linked into a 2D network via O3–H43ꢀꢀꢀN1 (N atoms
derived from 1,10-phenanthroline). The bond distance of H43ꢀꢀꢀN1
is 1.99(2) Å, which is consistent with the values in previous
literature [46]. The information hydrogen bonds were showed in
Table 3.
Fig. 3. 1D chain structure of the complex 1.

C. Zhu et al. / Inorganica Chimica Acta 375 (2011) 150–157
155
Fig. 4. Crystal structure of the complex 2.
Fig. 5. The 2D network of complex 2.
3.5.4. Crystal structure of complex (4)
and the angle of O–Sn–N is 175.92°. The distance between Sn
and N is 2.722 Å which is close to the Sn–N bond length reported
before [47,48]. The three C atoms of phenyl groups form an equa-
torial plane, and the sum of the trigonal plane angle is 356.06(6)°,
while the oxygen atom belonging to the carboxyl groups and the
nitrogen atom from 4,40-bipy occupy the axial apical position.
The molecular structure of complex 4 is shown in Fig. 8. The se-
lected bond lengths and angles are listed in Table 2. For complex 4,
the structure contains two Ph3Sn(O2CFc) units associated through
a bridging 4,40-bipy moiety. The geometry of Sn atom is trigonal
bipyramidal with a uncoordinated N atom derived of 4,40-bipy

156
C. Zhu et al. / Inorganica Chimica Acta 375 (2011) 150–157
Table 3
Geometry parameters of hydrogen bonding geometries for the ligand and complexes
2 and 3.
Complex 2
D–HꢀꢀꢀA
d(D–H)
0.98
0.98
d(HꢀꢀꢀA)
2.42
2.62
d(DꢀꢀꢀA)
3.38(2)
3.51(2)
angle (DHA)
169.6
151.3
C(10)–H(10)ꢀꢀꢀO(6)
C(37)–H(37)ꢀꢀꢀO(2)#3
Complex 3
D–HꢀꢀꢀA
d(D–H)
0.93
0.853(19)
0.93
d(HꢀꢀꢀA)
2.27
1.99(2)
2.61
d(DꢀꢀꢀA)
3.127(7)
2.839(5)
3.517(6)
angle (DHA)
153.0
175(5)
C(38)–H(38)ꢀꢀꢀO(2)#3
O(3)–H(43)ꢀꢀꢀN(1)#2
C(31)–H(31)ꢀꢀꢀO(1)
165.7
Symmetry transformations used to generate equivalent atoms for Complex 2: #1
ꢁx + 1, ꢁy + 1, ꢁz #2 ꢁx, ꢁy, ꢁz + 1 #3 x ꢁ 1, y, z; for complex 3: #1 ꢁx + 1, ꢁy + 1,
ꢁz + 1 #2 x ꢁ 1, y, z #3 x + 1, y + 1, z.
Fig. 7. The 2D network of complex 3.
3.6. Antitumor activities
Complexes 1–4 were screened for the in vitro tumor-inhibiting
activity against P388 cell line and Hela cell line. The inhibitory con-
centration IC50 has been assayed for complexes 1–4, the corre-
sponding IC50 values for P388 and Hela cell lines are listed in
Table 4. The results show that complexes 1 and 2 exhibit medium
activity towards P388 cell lines and Hela cell lines, complexes 3
and 4 also exhibit medium activity towards P388 cell lines but
strong activity towards Hela cell lines, which is more activity than
the reported organotin(IV) compounds [12,13,49]. In these four
complexes, complexes 3 and 4 more activity than complexes 1
and 2, which may result from complexes 3 and 4 include the neu-
tral molecules 1,10-phenanthroline and 4,40-bipy.
4. Conclusion
In conclusion, four new organotin(IV) complexes with ferro-
cenecarboxylic acid ligand has been successfully synthesized and
characterized by elemental analyses, IR, NMR spectra and X-ray
single-crystal diffraction. All the tin atoms in complexes 1–4 dis-
play five-coordinated trigonal bipyramid geometry. In complexes
2–4, ferrocenecarboxylate acts as monodentate ligand, while in
complex 1 it was a bidentate ligand. Complex 1 is a one-dimen-
sional polymer with the carboxylato groups acting as the bridge
to connect the tin units. Complexes 2 and 3 are able to assemble
into supramolecular framework through C–HꢀꢀꢀO and O–HꢀꢀꢀN weak
interactions. Antitumor activities of complexes 1–4 have also been
tested. Complexes 1 and 2 exhibit medium activity towards P388
Fig. 6. Crystal structure of the complex 3.
Being similar to the complexes 2 and 3, ferrocenecarboxylic acid is
also monodentate ligand in this complex and the distance of the
Sn1–O2 bond is 2.094(5) Å.
Fig. 8. Crystal structure of the complex 4.

C. Zhu et al. / Inorganica Chimica Acta 375 (2011) 150–157
157
Table 4
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(2010) 2134.
Half maximal inhibitory concentration (IC50
lines.
lM) of complexes 1–4 against tumor cell
Tumor cell line
Complex 1
Complex 2
Complex 3
Complex 4
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(2010) 346.
Hela
P388
3.56
4.12
2.28
3.20
0.79
2.44
0.65
2.54
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IC50 > 1 ꢂ 10ꢁ4 mol/L
(inactivity);
IC50 6 1 ꢂ 10ꢁ4 mol/L
(weak
activity);
IC50 6 1 ꢂ 10ꢁ5 mol/L (medium activity); IC50 6 1 ꢂ 10ꢁ6 mol/L (strong activity).
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ium activity towards P388 cell lines but strong activity towards
Hela cell lines.
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This work was supported by the National Natural Science Foun-
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CCDC 784813, 784816, 784814, and 784815 contain the supple-
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tively. These data can be obtained free of charge from The
Cambridge Crystallographic Data Centre via www.ccdc.cam.ac.uk/
data_request/cif. Supplementary data associated with this article
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