Macrocyclic organotin(IV) carboxylates based on benzenedicarboxylic acid derivatives: Syntheses, crystal structures and antitumor activities

Article abstract of DOI:10.1016/j.jorganchem.2011.03.048

Six new organotin carboxylates based on 1,3-benzenedicarboxylic acid and 1,4-benzenedicarboxylic acid derivatives, namely (Ph₃Sn) ₂(2,5-L¹)(C₂H₅OH)₂ (1) (2,5-H₂L¹ = 2,5-dibenzoylterephthalic acid), (Ph ₃Sn)₂(2,5-L²)(C₂H ₅OH)₂ (2) (2,5-H₂L² = 2,5-bis(4-methylbenzoyl)terephthalic acid), (Ph₃Sn) ₂(2,5-L³)(C₂H₅OH)₂ (3) (2,5-H₂L³ = 2,5-bis(4-ethylbenzoyl)terephthalic acid), [(n-Bu₂Sn)₄(4,6-L¹)O₂(OH)(OC ₂H₅)]₂·2(C₂H₅OH) (4) (4,6- H₂L¹ = 4,6-dibenzoylisophthalic acid), [(n-Bu₂Sn)₄(4,6-L¹)O₂(OH)(OC ₄H₉)]₂·2(C₄H₉OH) (5) and [(n-Bu₂Sn)₄(4,6-L²)O ₂(OH)(OC₂H₅)]₂·2(C ₂H₅OH) (6) (4,6-H₂L² = 4,6-bis(4-methylbenzoyl)isophthalic acid), have been synthesized. All the organotin carboxylates have been characterized by elemental analysis, IR, ¹H and ¹³C NMR spectroscopy and X-ray crystallography diffraction analyses. The structural analysis reveals that complexes 1-3 show similar structures, containing binuclear triorganotin skeletons. The significant intermolecular O-H?O hydrogen bonds linked the complexes 1-3 to form a novel 2D network polymer with 38-member macrocycles. In complexes 4-6, two Sn₄O₄ ladders are connected by two 1,3-benzenedicarboxylic acid derivatives to yield ladder-like octanuclear architectures and form macrocycle with 24 atoms. In addition, the antitumor activities of complexes 1-6 have been studied.

Full text of DOI:10.1016/j.jorganchem.2011.03.048

Journal of Organometallic Chemistry 696 (2011) 2549e2558
Contents lists available at ScienceDirect
Journal of Organometallic Chemistry
journal homepage: www.elsevier.com/locate/jorganchem
Macrocyclic organotin(IV) carboxylates based on benzenedicarboxylic acid
derivatives: Syntheses, crystal structures and antitumor activities
,
a
Dafeng Du a, Zijiang Jiang b, Chunling Liu a, Adama Moussa Sakho a, Dongsheng Zhu a , Lin Xu
*
a Department of Chemistry, Northeast Normal University, 5268 Renmin Street, Changchun 130024, PR China
b Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, 5625 Renmin Street, Changchun 130022, PR China
a r t i c l e i n f o
a b s t r a c t
Article history:
Six new organotin carboxylates based on 1,3-benzenedicarboxylic acid and 1,4-benzenedicarboxylic acid
derivatives, namely (Ph3Sn)2(2,5-L1)(C2H5OH)2 (1) (2,5-H2L1
¼
2,5-dibenzoylterephthalic acid),
Received 21 January 2011
Received in revised form
23 March 2011
(Ph3Sn)2(2,5-L2)(C2H5OH)2 (2) (2,5-H2L2 ¼ 2,5-bis(4-methylbenzoyl)terephthalic acid), (Ph3Sn)2(2,5-
L3)(C2H5OH)2 (3) (2,5-H2L3
¼
2,5-bis(4-ethylbenzoyl)terephthalic acid), [(n-Bu2Sn)4(4,6-L1)
Accepted 29 March 2011
O2(OH)(OC2H5)]2$2(C2H5OH) (4) (4,6- H2L1
¼
4,6-dibenzoylisophthalic acid), [(n-Bu2Sn)4(4,6-L1)
O2(OH)(OC4H9)]2$2(C4H9OH) (5) and [(n-Bu2Sn)4(4,6-L2)O2(OH)(OC2H5)]2$2(C2H5OH) (6) (4,6-
H2L2 ¼ 4,6-bis(4-methylbenzoyl)isophthalic acid), have been synthesized. All the organotin carboxylates
have been characterized by elemental analysis, IR, 1H and 13C NMR spectroscopy and X-ray crystallog-
raphy diffraction analyses. The structural analysis reveals that complexes 1e3 show similar structures,
containing binuclear triorganotin skeletons. The significant intermolecular OeH/O hydrogen bonds
linked the complexes 1e3 to form a novel 2D network polymer with 38-member macrocycles. In
complexes 4e6, two Sn4O4 ladders are connected by two 1,3-benzenedicarboxylic acid derivatives to
yield ladder-like octanuclear architectures and form macrocycle with 24 atoms. In addition, the anti-
tumor activities of complexes 1e6 have been studied.
Keywords:
Organotin(IV) carboxylates
1,3-Benzenedicarboxylic acid derivatives
1,4-Benzenedicarboxylic acid derivatives
Crystal structure
Antitumor activities
Ó 2011 Elsevier B.V. All rights reserved.
1. Introduction
1,3,5-benzene-tricarboxylic acid have been widely used for the
design and synthesis of the organotin carboxylates [21,22]. As far as
There is considerable interest in the assembly and structural
analysis of organotin complexes [1e3]. So far, a large number of
organotin complexes have been prepared and structurally charac-
terized because of their biological properties as well as their
unusual structural motifs [4e6]. Among them, organotin carbox-
ylates are particularly interesting because of their potential
industrial applications and topological structures [7e10]. Recently,
considerable advances have been made in this area, mono-, dicar-
boxylic acids and tricarboxylic acids have been extensively inves-
tigated [11e20]. The diverse structural motifs found in this family of
complexes are attributed to the coordinate characterization of the
carboxylate ligands. It is therefore necessary to select the new
carboxylate ligands with different structural features. Typically,
1,3-benzenedicarboxylic acid, 1,4-benzenedicarboxylic acid and
we know, no organotin carboxylates based on 1,3-benzenedi-
carboxylic acid and 1,4-benzenedicarboxylic acid derivatives have
been reported. To further understand the coordination chemistry of
1,3-benzenedicarboxylic acid and 1,4-benzenedicarboxylic acid
derivatives and to prepare novel organotin carboxylates with
beautiful architecture and good antitumor activities, we start to
elaborate and synthesize 1,3-benzenedicarboxylic acid and 1,4-
benzenedicarboxylic acid derivatives: 2,5-H2L1, 4,6-H2L1, 2,5-H2L2,
4,6-H2L2, 2,5-H2L3 and 4,6-H2L3, by reaction of pyromellitic dia-
nhydride with benzene, toluene, and ethylbenzene (Scheme 1),
respectively. The self-assembly of rigid aryl dicarboxylate (H2L
ligands) with triphenyltin hydroxide and di-n-butyltin oxide form
a series of novel organotin carboxylates (Scheme 2). In the present
paper, we report the syntheses, crystal structures and antitumor
activities of six macrocyclic organotin carboxylates, (Ph3Sn)2(2,5-
L1)(C2H5OH)2 (1), (Ph3Sn)2(2,5-L2)(C2H5OH)2 (2), (Ph3Sn)2(2,5-L3)
(C2H5OH)2 (3), [(n-Bu2Sn)4(4,6-L1)O2(OH)(OC2H5)]2$2(C2H5OH) (4),
[(n-Bu2Sn)4(4,6-L1)O2(OH)(OC4H9)]2$2(C4H9OH) (5) and [(n-Bu2-
Sn)4(4,6-L2)O2(OH)(OC2H5)]2$2(C2H5OH) (6).
* Corresponding author. Tel.: þ86 043185098620; fax: þ86 0431 85098768.
E-mail address: zhuds206@nenu.edu.cn (D. Zhu).
0022-328X/$ e see front matter Ó 2011 Elsevier B.V. All rights reserved.
doi:10.1016/j.jorganchem.2011.03.048

2550
D. Du et al. / Journal of Organometallic Chemistry 696 (2011) 2549e2558
Scheme 1. The reaction scheme for the syntheses of H2L1, H2L2 and H2L3.
2. Experimental
of incubation at 37 ꢁC, then 200
ml of DMSO was added to each well.
The optical density (OD) was then read at a wavelength of 570 nm.
The decrease in OD measures the extent of decrease in the number of
cancer cells exposed to the test compounds.
2.1. General and instrumental
The reagents were used as supplied, while the solvents were
purified according to standard procedures [23]. The melting point
was obtained with Kofler micro-melting point apparatus and was
uncorrected. Elemental analyses (C, H) were carried out on a Per-
kineElmer PE 2400 CHN instrument. 1H and 13C NMR spectra were
recorded on a Varian Mercury operating at 300 and 75 MHz,
respectively. IR spectra (KBr pellets) were recorded on an Alpha
Centauri FI/IR spectrometer (400e4000 cmꢀ1 range).
2.4. Syntheses
The details of synthetic experiments of ligands and complexes
1e6 were shown in Scheme 1 and Scheme 2.
2.4.1. Syntheses of ligands
2,5-H2L1 (para) and 4,6-H2L1 (meta) were prepared by a stan-
dard method reported in the literature [27]. Typically, pyromellitic
dianhydride (4.36 g, 0.02 mol), anhydrous aluminum chloride
(10.67 g, 0.08 mol) and dry benzene (18.75 g, 0.24 mol) were added
into a three-neck flask. The reaction mixture was stirred for 3 h in
a water-bath at 65e70 ꢁC. The mixture is then poured into ice water
of containing concentrated hydrochloric acid, which is distilled in
a current of steam. When the benzene has been completely
removed, the crude mixtures of acids produced are left in the form
of white. These are washed with water, and dissolved in boiling
dilute potassium hydroxide solution. After filtration to remove
a little insoluble matter, the usual mixture of meta and para are
obtained with hydrochloric acid (Yield: 73.4%). Separated by crys-
tallization from glacial acetic acid, the para could be obtained first
from glacial acetic acid. The meta usually crystallized upon aqueous
dilution of the filtrates [28]. The para and meta isomers are
obtained in a ratio of 4:3. For para: Mp: 318e321 ꢁC 1H NMR
2.2. X-ray crystallography
Diffraction intensities for 1e6 were collected on a Bruker CCD
Area Detector image plate diffractometer by using the
u
/4
scan
technique with Mo-K radiation (
a
l
¼ 0.71073 Å). Absorption
corrections were applied by using multiscan techniques. The
structure was solved by direct methods with SHELXS-97 [24] and
refined using SHELXL-97 [25]. All non-hydrogen atoms were refined
with anisotropic temperature parameters; hydrogen atoms were
refined as rigid groups. Crystal data and refinement results for 1e6
are listed in Tables 1 and 3.
2.3. Antitumor studies
HeLa (cervical), HT1080 (fibrosarcoma) and U87 (glioma) were
obtained from the American Tissue Culture Collection (ATCC). The
cells were cultured with culture reagents and dissolved in dimethyl
sulfoxide (DMSO) and stored at 4 ꢁC. The [3-(4,5-dimethylthiazol-2-
yl)-2,5-diphenyl tetrazolium bromide] (MTT) assay that differenti-
ates dead from living cells was adapted [26]. The assay was carried
out as follows: A total of 1 ꢂ 104 cells were seeded into a 96-well
microplate and incubated for 24 h. Thereafter, the cells were treated
with various concentrations of both complexes 1e6 for 24 h. The
MTT (final concentration ¼ 0.5 mg/ml) was added toeach well for 4 h
(acetone-d6, 300 MHz):
J ¼ 7.5 Hz, AreH); 7.87 (d, 4H, J ¼ 7.2 Hz, AreH); 8.10 (s, 2H, AreH).
13C NMR (acetone-d6, 75 MHz):
194.96 (C]O); 166.13 (COO);
144.76, 142.38, 133.69, 132.21, 129.71, 129.03 (4C), 127.18 (4C),
(carbon protons of aryl groups); (all peaks 2C unless otherwise
noted). For meta: Mp: 278e280 ꢁC 1H NMR (acetone-d6, 300 MHz):
d
7.55 (t, 4H, J ¼ 7.5 Hz, AreH); 7.67 (t, 2H,
d
d
7.52 (t, 4H, J ¼ 7.5 Hz, AreH); 7.64 (t, 2H, J ¼ 7.5 Hz, AreH); 7.82 (d,
4H, J ¼ 7.2 Hz, AreH); 8.10 (s, 1H, AreH); 8.78 (s, 1H, AreH). 13C
NMR (acetone-d6, 75 MHz):
d 195.16 (C]O); 165.82 (COO); 147.26,
Scheme 2. The reaction scheme for the syntheses of 1e6.

D. Du et al. / Journal of Organometallic Chemistry 696 (2011) 2549e2558
2551
2.4.2. Synthesis of (Ph3Sn)2(2,5-L1)(C2H5OH)2 1
Table 1
Crystal data and details of structure refinement parameters for 1e3.
A mixture of triphenyltin hydroxide (0.73 g, 2 mmol) and 2,5-
H2L1 (0.37 g, 1 mmol) was heated under reflux in benzene (30 ml)
for 10 h in a DeaneStark apparatus for azeotropic removal of the
water formed in the reaction. After cooling to room temperature,
the reaction mixture was filtered and evaporated to afford the
products at room temperature. The products were then recrystal-
lized from ethanol to give colorless crystals. Yield: 72.6%; Mp:
100e102 ꢁC. Anal. Calcd for C62H54O8Sn2: C, 63.95; H, 4.67. Found:
C, 63.82; H, 4.81%. IR (cmꢀ1): v (CeH) 2962, 2909; vas (COO) 1652,
1
2
3
Empirical formula
Formula weight
Crystal system
Space group
a (Å)
C62H54O8Sn2
1164.43
Monoclinic
P 2(1)/c
9.8933(7)
14.1532(10)
19.2542(13)
90.0
95.2630(10)
90.0
2684.6(3)
2
C64H58O8Sn2
1192.48
Monoclinic
P 2(1)/c
10.0462(8)
14.6232(11)
19.4363(15)
90.0
98.6660(10)
90.0
C66H62O8Sn2
1220.54
Monoclinic
P 2(1)/n
10.3408(7)
14.5643(10)
19.6272(13)
90.0
100.0610(10)
90.0
b (Å)
c (Å)
a
b
g
(ꢁ)
(ꢁ)
(ꢁ)
1608; vs (COO) 1436, 1385;
6.91e7.71 (m, 40H, AreH); 8.12 (s, 2H, AreH); 3.63 (q, 4H,
n
(SneO) 457. 1H NMR (CDCl3, ppm):
d
V (Å3)
2822.7(4)
2
0.939
2910.5(3)
2
0.912
J ¼ 7.2 Hz, eCH2e, hydrogen protons of ethyl groups); 1.14 (t, 6H,
Z
m
J ¼ 6.9 Hz, eCH3, hydrogen protons of ethyl groups). 13C NMR
(mmꢀ1
)
0.985
Reflections collected
Independent Reflections
R(int)
22553
5277
0.0931
14058
4954
0.0221
24427
5736
0.0869
(CDCl3, ppm): d 194.56 (C]O); 171.45 (COO); 149.68, 147.32, 144.16,
138.65,136.49,134.76,132.18,130.56,129.48,128.69,126.56 (carbon
protons of aryl groups); 57.69 (C- , carbon protons of ethanol);
18.47 (C- , carbon protons of ethanol).
a
Final R indices [I > 2
R indices (all data)
s(I)]
0.0373, 0.0720
0.0724, 0.0803
0.0309, 0.0795
0.0431, 0.0834
0.0396, 0.0801
0.0883, 0.0917
b
2.4.3. Synthesis of (Ph3Sn)2(2,5-L2)(C2H5OH)2
2
The preparation of 2 is similar to that of 1 except that the 2,5-
H2L2 (0.40 g, 1 mmol) was used to take place of 2,5-H2L1. Yield: 76%;
Mp: 102e105 ꢁC. Anal. Calcd for C64H58O8Sn2: C, 64.46; H, 4.90.
Found: C, 64.12; H, 4.68%. IR (cmꢀ1): v (CeH) 2926, 2782; vas (COO)
1654, 1604; vs (COO) 1428, 1382; v (SneO) 450. 1H NMR (CDCl3,
137.17, 133.69, 132.54, 131.25 (1C), 129.58 (1C), 129.00 (4C), 127.45
(4C), (carbon protons of aryl groups); (all peaks 2C unless otherwise
noted).
The preparation of 2,5-H2L2 (para) and 4,6-H2L2 (meta) is similar
to that of H2L1 except that the dry toluene (22.11 g, 0.24 mol) was
used to take place of dry benzene (Yield: 69.2%). The separation of
two isomers is similar to that of 2,5-H2L1and 4,6-H2L1. The para and
meta isomers are obtained in a ratio of 4:1. For para: Mp:
ppm):
d 7.01e7.55 (m, 38H, AreH); 8.09 (s, 2H, AreH); 2.32 (s, 6H
AreCH3); 3.47 (q, 4H, J ¼ 7.2 Hz, eCH2e, hydrogen protons of ethyl
groups); 1.23 (t, 6H, J ¼ 7.2 Hz, eCH3, hydrogen protons of ethyl
groups). 13C NMR (CDCl3, ppm):
d 195.97 (C]O); 171.86 (COO);
332e335 ꢁC 1H NMR (acetone-d6, 300 MHz):
d
7.38 (d, 4H,
J ¼ 8.1 Hz, AreH); 7.76 (d, 4H, J ¼ 8.1 Hz, AreH); 8.12 (s, 2H, AreH);
2.37 (s, 6H, eCH3). 13C NMR (acetone-d6, 75 MHz):
194.86 (C]O);
144.17, 143.28, 137.71, 137.11, 136.79, 134.76, 130.53, 130.00, 129.62,
129.20, 128.77 (carbon protons of aryl groups); 57.64 (C- , carbon
protons of ethanol); 21.13 (C, carbon protons of methyl groups of 4-
methylphenyl groups), 18.62 (C- , carbon protons of ethanol).
a
d
165.53 (COO); 144.58, 142.58,134.88, 132.21, 129.89, 127.45 (4C),
125.87 (4C), (carbon protons of aryl groups); 21.11 (C, carbon
protons of methyl groups of 4-methylphenyl groups); (all peaks 2C
unless otherwise noted). For meta: Mp: 289e291 ꢁC 1H NMR
b
2.4.4. Synthesis of (Ph3Sn)2(2,5-L3)(C2H5OH)2
3
The preparation of 3 is similar to that of 1 except that the 2,5-
H2L3 (0.43 g, 1 mmol) was used to take place of 2,5-H2L1. Yield:
68.2%; Mp: 108e111 ꢁC. Anal. Calcd for C66H62O8Sn2: C, 64.94; H,
5.12. Found: C, 64.82; H, 5.31%. IR (cmꢀ1): v (CeH) 2971, 2926; vas
(acetone-d6, 300 MHz):
J ¼ 8.1 Hz, AreH); 7.47 (s, 1H, AreH); 8.77 (s, 1H, AreH); 2.34 (s, 6H,
eCH3). 13C NMR (acetone-d6, 75 MHz):
194.83 (C]O); 165.49
d
7.34 (d, 4H, J ¼ 7.8 Hz, AreH); 7.71 (d, 4H,
d
(COO); 146.49, 144.59, 134.75, 132.55, 130.65 (1C), 129.76 (1C),
127.20 (4C), 125.87 (4C), (carbon protons of aryl groups); 21.12 (C,
carbon protons of methyl groups of 4-methylphenyl groups); (all
peaks 2C unless otherwise noted).
(COO) 1646, 1603; vs (COO) 1428, 1388;
(CDCl3, ppm): 6.84e7.56 (m, 38H, AreH); 8.08 (s, 2H, AreH); 1.25
n
(SneO) 451. 1H NMR
d
(t, 6H, J ¼ 6.9 Hz, AreCeCH3); 2.64 (q, 4H, J ¼ 7.5 Hz, AreCH2e);
3.71 (q, 4H, J ¼ 7.2 Hz, eCH2e, hydrogen protons of ethyl groups);
The preparation of 2,5-H2L3 (para) and 4,6-H2L3 (meta) is similar
to that of H2L1 except that the dry ethylbenzene (25.48 g, 0.24 mol)
was used to take place of dry benzene (Yield: 68.8%). The separation
of two isomers is similar to that of 2,5-H2L1 and 4,6-H2L1. The para
and meta isomers are obtained in a ratio of 6:1. For para: Mp:
1.18 (t, 6H, J ¼ 7.5 Hz, eCH3, hydrogen protons of ethyl groups). 13
C
NMR (CDCl3, ppm):
d 196.10 (C]O); 170.31 (COO); 150.33, 147.47,
143.37, 137.45, 136.80, 134.94, 133.16, 130.21, 129.21, 128.79, 125.11
(carbon protons of aryl groups); 58.81 (C- , carbon protons of
ethanol); 29.36 (C- , carbon protons of ethyl groups of 4-ethyl-
phenyl groups); 18.80 (C- , carbon protons of ethanol); 15.85 (C-
carbon protons of ethyl groups of 4-ethylphenyl groups).
a
a
347e350 ꢁC 1H NMR (acetone-d6, 300 MHz):
d
7.41 (d, 4H,
b
b,
J ¼ 7.8 Hz, AreH); 7.79 (d, 4H, J ¼ 8.1 Hz, AreH); 8.07 (s, 2H, AreH);
2.73 (q, 4H, J ¼ 6.9 Hz, eCH2e); 1.25 (t, 6H, J ¼ 6.9 Hz, eCH3). 13
C
NMR (acetone-d6, 75 MHz):
d
194.85 (C]O); 165.56(COO); 150.73,
2.4.5. Synthesis of [(n-Bu2Sn)4(4,6-L1)O2(OH)(OC2H5)]2$2(C2H5OH)
132.95, 130.60, 130.01, 129.69, 128.51 (4C), (carbon protons of aryl
groups); 125.26 (4C); 27.28 (C- , carbon protons of ethyl groups of
4-ethylphenyl groups); 15.62 (C- , carbon protons of ethyl groups
of 4-ethylphenyl groups) (all peaks 2C unless otherwise noted). For
meta: Mp: 308e311 ꢁC 1H NMR (acetone-d6, 300 MHz):
7.35 (d,
4
a
A mixture of di-n-butyltin oxide (0.99 g, 4 mmol) and 4,6-H2L1
(0.37 g, 1 mmol) was heated under reflux in benzene (30 ml) for
10 h in a DeaneStark apparatus for azeotropic removal of the water
formed in the reaction. After cooling to room temperature, the
reaction mixture was filtered and evaporated to afford the products
at room temperature. The products were then recrystallized from
ethanol to give colorless crystals. Yield: 75.7%; Mp: 292e295 ꢁC.
Anal. Calcd for C116H192O22Sn8: C, 48.24; H, 6.70. Found: C, 48.27; H,
6.74%. IR (cmꢀ1): v (CeH) 2957, 2925, 2862; vas (COO) 1635, 1605; vs
b
d
4H, J ¼ 8.1 Hz, AreH); 7.74 (d, 4H, J ¼ 8.1 Hz, AreH); 8.07 (s, 1H,
AreH); 8.78 (s, 1H, AreH); 2.71 (q, 4H, J ¼ 7.2 Hz, eCH2e); 1.25 (t,
6H, J ¼ 7.2 Hz, eCH3). 13C NMR (acetone-d6, 75 MHz):
d 194.82 (C]
O); 165.45 (COO); 149.56, 146.93,134.98,132.94,130.62 (1C),129.00
(1C), 127.23 (4C), 125.85 (4C), (carbon protons of aryl groups); 27.36
(C-
15.51 (C-
groups); (all peaks 2C unless otherwise noted).
a
, carbon protons of ethyl groups of 4-ethylphenyl groups);
(COO) 1397, 1340; v (SneO) 494;
ppm): 6.91e7.77 (m, 20H, AreH); 8.01 (s, 2H, AreH); 8.73 (s, 2H,
AreH); 1.19e1.56 (m, 96H, SnCH2CH2CH2e); 0.86 (t, 48H, J ¼ 7.2 Hz,
n
(SneOeSn) 608. 1H NMR (CDCl3,
b, carbon protons of ethyl groups of 4-ethylphenyl
d

2552
D. Du et al. / Journal of Organometallic Chemistry 696 (2011) 2549e2558
eCH3). 13C NMR (CDCl3, ppm):
d
197.21 (C]O); 170.72 (COO);
2.4.6. Synthesisof[(n-Bu2Sn)4(4,6-L1)O2(OH)(OC4H9)]2$2(C4H9OH)5
144.51, 137.71, 134.54, 133.81, 133.15, 129.82, 128.70, 125.74 (carbon
protons of aryl groups); 27.43 ( CH2), 25.04 ( CH2), 23.75 ( CH2),
13.95 (CH3) (carbon protons of butyl groups).
The preparation of 5 is similar to that of 4 except that the n-
butanol was used to take place of alcohol. Yield: 61.4%; Mp:
298e300 ꢁC. Anal. Calcd for C124H208O22Sn8: C, 49.63; H, 6.99.
a
b
g
Fig. 1. Perspective views of the molecular structure of complexes 1e3.

D. Du et al. / Journal of Organometallic Chemistry 696 (2011) 2549e2558
2553
Found: C, 49.67; H, 6.95%. IR (cmꢀ1): v (CeH) 2953, 2916, 2878; vas
(COO) 1641, 1612; vs (COO) 1391, 1332; v (SneO) 483; (SneOeSn)
601. 1H NMR (CDCl3, ppm):
6.87e7.71 (m, 20H, AreH); 8.03 (s, 2H,
n
d
AreH); 8.76 (s, 2H, AreH); 1.17e1.55 (m, 96H, SnCH2CH2CH2e);
0.83 (t, 48H, J ¼ 7.2 Hz, eCH3). 13C NMR (CDCl3, ppm):
d 197.12 (C]
O); 170.86 (COO); 144.34, 137.85, 135.82, 133.76, 132.29, 130.07,
128.95, 125.81 (carbon protons of aryl groups); 27.31 (
aCH2), 25.09
(b
CH2), 23.76 ( CH2), 13.91 (CH3) (carbon protons of butyl groups).
g
2.4.7. Synthesisof[(n-Bu2Sn)2(4,6-L2)O2(OH)(OC2H5)]2$2(C2H5OH)6
The preparation of 6 is similar to that of 4 except that the 4,6-
H2L2 (0.402 g, 1 mmol) was used to take place of 4,6-H2L1. Yield:
69.1%; Mp: 296e298 ꢁC. Anal. Calcd for C120H200O22Sn8: C, 48.95; H,
6.85. Found: C, 48.67; H, 6.78%. IR (cmꢀ1): v (CeH) 2956, 2924,
2862; vas (COO) 1634, 1605; vs (COO) 1398, 1341; v (SneO) 493;
n
(SneOeSn) 611. 1H NMR (CDCl3, ppm):
d
6.91e7.65 (m, 16H, AreH);
8.01 (s, 2H, AreH); 8.72 (s, 2H, AreH); 2.38 (s, 12H, AreCH3);
1.16e1.62 (m, 96H, SnCH2CH2CH2e); 0.88 (t, 48H, J ¼ 6.9 Hz, eCH3).
13C NMR (CDCl3, ppm):
d 197.00 (C]O); 170.79 (COO); 144.65,
143.78, 135.54, 133.99, 133.79, 129.96, 129.39, 125.77 (carbon
protons of aryl groups); 27.44 ( CH2), 25.06 ( CH2), 23.74 ( CH2),
a
b
g
13.94 (CH3) (carbon protons of butyl groups); 21.99, (C, carbon
protons of methyl groups of 4-methylphenyl groups).
3. Results and discussion
3.1. IR spectra
For the organotin carboxylates 1e6, the stretching frequencies
of interests are those associated with the COO, SneO and SneOeSn
groups. The bands at 3100e3550 cmꢀ1 which appear in the free
ligands H2L1, H2L2 and H2L3 as the
n (OeH) stretching vibrations, are
not observed in complexes 1e6, thus indicating metaleligand bond
formation through these sites. The two different absorption bands
in the ranges of 1603e1654 cmꢀ1 and 1332e1436 cmꢀ1 correspond
to the nas (COO) and ns (COO) modes of the coordinated carbonyl
groups, respectively. Deacon has proposed that Dn
[
nas (COO) ꢀ ns
(COO)] values >200 cmꢀ1 are associated with unidentated coor-
dination [29]. The Dn values of the complexes 1e3 and 4e6 are
about 215e226 and 236e280 cmꢀ1, which indicate that the
carboxylate ligands L1, L2 and L3 coordinate to the Sn atoms in the
manner of monodentates. The Dn values of the complexes 1e6 are
close to 200 cmꢀ1, which indicates that Sn/O interactions exist
between tin atoms and non-bonded oxygen atoms of carboxyl
groups. The Dn values of the complexes 1e3 are smaller than those
of 4e6, which indicates that Sn/O interactions in 1e3 are stronger
than those of 4e6. This was confirmed by X-ray structural analysis.
A band in the 450e494 cmꢀ1 region is assigned to the stretching
frequency associated with the SneO bond. A strong band in
601e611 cmꢀ1 for complexes 4e6 is assigned to
indicating a SneOeSn bridged structure [30].
n (SneOeSn),
3.2. NMR spectra
In the 1H NMR spectra of the H2L1, H2L2 and H2L3 ligands, the
signal of the two hydrogen protons on central aromatic rings in the
4,6-H2L ligand has one more than that of the corresponding 2,5-H2L
ligand. The COOH group resonance appears at 11e12 ppm [31].
However, this resonance disappears when the carboxylate group
participated in coordination to the Sn atom in complexes 1e6. The
same chemical shifts of the two hydrogen protons on central
aromatic rings of complexes 1e3 exhibit signals at 8.08e8.12 ppm
as single peak, and the different chemical shifts of the two
hydrogen protons on central aromatic rings of complexes 4e6 at
8.01e8.03 and 8.72e8.76 ppm as single peak and the chemical
Fig. 2. The 2D supramolecular structures with 38-member macrocycles formed
through intermolecular OeH/O hydrogen-bond interactions in complexes 1e3.

2554
D. Du et al. / Journal of Organometallic Chemistry 696 (2011) 2549e2558
shifts of the hydrogen protons on the other phenyl groups of
complexes 1e6 at 6.84e7.77 ppm as multiplets.
intermolecular coordinative bond. The Sn1eO (oxygen atom of
carboxylate ligand) (O2 for 1; O3 for 2; O2 for 3) bond lengths of 1e3
are 2.158(2), 2.148 (2) and 2.135(3) Å, respectively, which prove that
the carboxylate O atom is coordinated to the tin atom by a strong
chemical bond. However, the Sn1/O (oxygen atom of carboxylate
ligand) (O3 for 1; O2 for 2; O1 for 3) distances (3.122 Å for 1; 3.061 Å
for 2; 3.097 Å for 3) are considerably shorter than the sum of the van
der Waals radii of the Sn and O atom (3.68 Å), therefore the oxygen
atom is involved in intramolecular interactions with tin [32]. If the
weak Sn(1)/O interaction is taken into consideration, the geometry
of tin atoms is best described as distorted octahedron. In addition,
the distance between Sn1 and Sn1A in 1e3 decrease in the order of 3
(11.487 Å) > 2 (11.437 Å) > 1 (11.431 Å), and this phenomenon is
attributed to the volume of group (ethylbenzoyl > methyl-
benzoyl > benzoyl) on central aromatic ring.
The 13C NMR spectra of the complexes 1e6 show a significant
downfield shift of all carboxylate carbon resonances compared with
the free ligands H2L1, H2L2 and H2L3. The shift is a consequence of
electron density transfer from the ligand to the Sn atom. The carbon
protons of central aromatic rings present three and four kinds of
chemical environment in complexes 1e3 and complexes 4e6,
respectively. The single resonances at 194.56e197.21 and
170.72e171.86 are attributed to the C]O and COO groups in
complexes 1e6. These data are consistent with the structures of 1e6.
3.3. Crystal structures
3.3.1. Crystal structures of 1e3
Besides, for complexes 1e3, intermolecular hydrogen-bond
interactions between the ethanol and the oxygen atom of carbonyl
in an adjacent molecule [O(1)eH/O(4A) ¼ 2.829 Å for 1, O(1)e
H/O(4A) ¼ 2.820 Å for 2, and O(3)eH/O(4A) ¼ 2.884 Å for 3] result
in the formation of a two dimensional network. It is noteworthy that
the 38-member of complex 1e3 is formed via the two intermolec-
ular OeH/O interactions. As can be seen from Fig. 2, the infinite
macrocycles constitute 2D supramolecular structures.
The molecular and 2D supramolecular structures of 1e3 are
shown in Figs.1 and 2, respectively, selected bond lengths and angles
for 1e3 are given in Table 2. From the structures we can see that the
complexes 1e3 show similar structures, containing binuclear tri-
organotin skeletons. In the complexes 1e3, each of the twotin atoms
has a coordination number of five. The geometry at Sn1 is a distorted
trigonal bipyramid with the ethanolic oxygen (O1 for 1; O1 for 2; O3
for 3) and the carboxylate O atom (O2 for 1; O3 for 2; O2 for 3) in the
axial sites. Three phenyl carbon atoms (C3, C9 and C15 for 1; C15, C21
and C27 for 2; C3, C9 and C15 for 3) occupy the equatorial plane. The
axial OeSn1eO angles of 1e3 are not 180ꢁ but 174.81(9)ꢁ for
O2eSn1eO1 of 1, 174.16(9) for O3eSn1eO1 of 2, and 171.88(11)ꢁ for
O2eSn1eO3 of 3, which prove the distortion of the geometry. The
Sn1eO (ethanolic oxygen atom) bond lengths of 1e3 are 2.447(3),
2.473(2), and 2.515(3) Å, which are slightly longer than the SneO
covalent bond length (2.13 Å) but considerably shorter than the sum
of the van der Waals radii of the two atoms (3.68 Å) [32]. It indicates
that the ethanolic oxygen atom and tin atom form a stable
3.3.2. Crystal structures of 4e6
Selected bond distances and angles for 4e6 are listed in
Tables 4e6, and the structures of 4e6 are shown in Figs. 3e5,
respectively. Each of the three structures consists of two novel
Sn4O4 ladders connected by two carboxylate ligands. These struc-
tures of the ladder parts are very similar to the complex [(iPrOCS2)
Me2Sn(OEt)OSnMe2]2 which features
a centrosymmetric core
arranged as a ladder [33]. In the Sn4O4 ladders, the four tin atoms
are almost coplanar, with the largest deviation being 0.0181 Å for 4,
0.0659 Å for 5 and 0.0589 Å for 6. According to their different
coordination environments, the four tin atoms can be divided into
two types: the endocyclic tin (Sn1 and Sn4 for 4; Sn2 and Sn3 for 5;
Sn2 and Sn3 for 6) and the exocyclic tin (Sn2 and Sn3 for 4; Sn1 and
Sn4 for 5; Sn1 and Sn4 for 6). The endocyclic and exocyclic tin
atoms are connected by the m3-oxygen atoms (O1 and O2 for 4; O2
and O3 for 5; O8 and O9 for 6) and the m2-oxygen atoms (O3 and
ethanolic oxygen O4 for 4; O4 and butanolic oxygen O1 for 5; O10
and ethanolic oxygen O7 for 6). All of the tin atoms of 4e6 are five-
coordinated by two n-Bu groups and three O atoms, resulting in
Table 2
Selected bond lengths (Å) and angles (ꢁ) for 1e3.
Complex 1
Bond lengths
Sn(1)eO(1)
Sn(1)eO(2)
Sn(1)eC(15)
2.447(3)
2.158(2)
2.131(4)
Sn(1)eC(9)
Sn(1)eC(3)
2.121(4)
2.118(4)
Bond angles
C(3)eSn(1)eC(9)
C(3)eSn(1)eC(15)
C(9)eSn(1)eC(15)
C(3)eSn(1)eO(2)
C(9)eSn(1)eO(2)
122.7(2)
122.21(15)
112.6(2)
95.00(12)
101.60(13)
C(15)eSn(1)eO(2)
C(3)eSn(1)eO(1)
C(9)eSn(1)eO(1)
C(15)eSn(1)eO(1)
O(2)eSn(1)eO(1)
89.25(13)
84.55(13)
82.92(13)
86.64(13)
174.81(9)
Table 3
Crystal data and details of structure refinement parameters for 4e6.
Complex 2
Bond lengths
Sn(1)eO(1)
Sn(1)eO(3)
Sn(1)eC(27)
4
5
6
2.473(2)
2.148(2)
2.117(3)
Sn(1)eC(21)
Sn(1)eC(15)
2.129(4)
2.124(4)
Empirical formula
Formula weight
Crystal system
Space group
a (Å)
C116H192O22Sn8 C124H208O22Sn8 C120H200O22Sn8
2888.22
Monoclinic
C2/c
29.5685(12)
21.4564(9)
24.6164(10)
119.5920(10)
13580.4(10)
4
1.413
1.504
5856
1.58, 26.04
37303
3000.42
Monoclinic
C2/c
30.0543(17)
21.3451(12)
25.1368(14)
120.2260(10)
13933.2(14)
4
1.430
1.468
6112
1.77, 26.03
38258
2944.32
Monoclinic
P2(1)/n
13.4647(8)
19.5797(12)
25.9828(16)
100.5710(10)
6733.7(7)
2
1.452
1.518
2992
1.59, 26.04
36938
Bond angles
C(27)eSn(1)eC(15)
C(27)eSn(1)eC(21)
C(15)eSn(1)eC(21)
C(27)eSn(1)eO(3)
C(15)eSn(1)eO(3)
121.35(13)
122.27(14)
114.07(14)
95.35(10)
88.62(11)
C(21)eSn(1)eO(3)
C(27)eSn(1)eO(1)
C(15)eSn(1)eO(1)
C(21)eSn(1)eO(1)
O(3)eSn(1)eO(1)
101.04(11)
84.05(10)
86.75(11)
84.12(11)
174.16(9)
b (Å)
c (Å)
b
(ꢁ)
V (Å3)
Complex 3
Bond lengths
Sn(1)eO(2)
Sn(1)eO(3)
Sn(1)eC(15)
Bond angles
C(15)eSn(1)eC(9)
C(15)eSn(1)eC(3)
C(9)eSn(1)eC(3)
C(15)eSn(1)eO(2)
C(9)eSn(1)eO(2)
Z
Dc (Mg/m3)
2.135(3)
2.515(3)
2.106(4)
Sn(1)eC(9)
Sn(1)eC(3)
2.114(5)
2.114(4)
m
(mmꢀ1
)
F(000)
q
Range (ꢁ)
Reflections collected
Independent reflections
R(int)
119.6(2)
121.8(2)
115.6(2)
96.64(14)
88.51(14)
C(3)eSn(1)eO(2)
C(15)eSn(1)eO(3)
C(9)eSn(1)eO(3)
C(3)eSn(1)eO(3)
O(2)eSn(1)eO(3)
101.97(15)
83.49(14)
84.40(14)
84.72(14)
171.88(11)
13262
0.0681
98.8%
0.937
13506
0.0337
98.4%
1.025
13257
0.0394
99.9%
1.024
Completeness to qmax
Goodness-of-fit (F2)
Final R indices [I > 2
s
(I)] 0.0488, 0.1145
0.0360, 0.0973
0.0522, 0.1214

D. Du et al. / Journal of Organometallic Chemistry 696 (2011) 2549e2558
2555
Table 4
Table 6
Selected bond lengths (Å) and angles (ꢁ) for 4.
Selected bond lengths (Å) and angles (ꢁ) for 6.
Sn(1)eO(2)
Sn(1)eC(34)
Sn(1)eC(30)
Sn(1)eO(1)
Sn(1)eO(3)
Sn(2)eO(1)
Sn(2)eC(55)
Sn(2)eC(48)
Sn(2)eO(7A)
Sn(2)eO(4)
2.043(3)
2.125(7)
2.130(6)
2.136(3)
2.168(4)
1.997(3)
2.113(8)
2.120(7)
2.162(4)
2.197(4)
Sn(3)eO(3)
Sn(3)eC(26)
Sn(3)eO(2)
Sn(3)eC(22)
Sn(3)eO(5)
Sn(4)eO(1)
Sn(4)eO(2)
Sn(4)eC(38)
Sn(4)eC(42)
Sn(4)eO(4)
2.047(3)
2.087(7)
2.107(3)
2.133(6)
2.263(4)
2.046(3)
2.099(3)
2.114(7)
2.122(7)
2.192(4)
Sn(1)eO(10)
Sn(1)eC(47)
Sn(1)eC(51)
Sn(1)eO(9)
Sn(1)eO(4A)
Sn(2)eO(9)
Sn(2)eC(39)
Sn(2)eC(35)
Sn(2)eO(8)
Sn(2)eO(10)
2.037(4)
2.106(7)
2.112(7)
2.114(4)
2.254(4)
2.029(4)
2.111(8)
2.115(8)
2.134(4)
2.192(4)
Sn(3)eO(8)
Sn(3)eC(43)
Sn(3)eO(9)
Sn(3)eC(57)
Sn(3)eO(7)
Sn(4)eO(8)
Sn(4)eC(27)
Sn(4)eC(31)
Sn(4)eO(1)
Sn(4)eO(7)
2.034(4)
2.116(10)
2.124(4)
2.129(9)
2.176(4)
2.016(4)
2.110(9)
2.134(7)
2.168(4)
2.204(4)
O(2)eSn(1)eC(34)
O(2)eSn(1)eC(30)
C(34)eSn(1)eC(30)
O(2)eSn(1)eO(1)
C(34)eSn(1)eO(1)
C(30)eSn(1)eO(1)
O(2)eSn(1)eO(3)
C(34)eSn(1)eO(3)
C(30)eSn(1)eO(3)
O(1)eSn(1)eO(3)
O(1)eSn(2)eC(55)
O(1)eSn(2)eC(48)
C(55)eSn(2)eC(48)
O(1)eSn(2)eO(7A)
C(55)eSn(2)eO(7A)
C(48)eSn(2)eO(7A)
O(1)eSn(2)eO(4)
C(55)eSn(2)eO(4)
C(48)eSn(2)eO(4)
O(7A)eSn(2)eO(4)
114.3(2)
115.9(2)
129.7(2)
74.48(13)
96.0(2)
96.5(2)
73.12(13)
97.1(2)
O(3)eSn(3)eC(26)
O(3)eSn(3)eO(2)
C(26)eSn(3)eO(2)
O(3)eSn(3)eC(22)
C(26)eSn(3)eC(22)
O(2)eSn(3)eC(22)
O(3)eSn(3)eO(5)
C(26)eSn(3)eO(5)
O(2)eSn(3)eO(5)
C(22)eSn(3)eO(5)
O(1)eSn(4)eO(2)
O(1)eSn(4)eC(38)
O(2)eSn(4)eC(38)
O(1)eSn(4)eC(42)
O(2)eSn(4)eC(42)
C(38)eSn(4)eC(42)
O(1)eSn(4)eO(4)
O(2)eSn(4)eO(4)
C(38)eSn(4)eO(4)
C(42)eSn(4)eO(4)
108.7(2)
74.35(13)
99.6(2)
109.10(19)
140.9(2)
99.52(19)
82.40(13)
86.6(2)
156.72(13)
89.02(19)
75.24(13)
117.2(2)
99.4(2)
117.2(2)
98.1(2)
125.4(3)
71.43(14)
146.67(14)
95.9(2)
O(10)eSn(1)eC(47)
O(10)eSn(1)eC(51)
C(47)eSn(1)eC(51)
O(10)eSn(1)eO(9)
C(47)eSn(1)eO(9)
C(51)eSn(1)eO(9)
O(10)eSn(1)eO(4A)
C(47)eSn(1)eO(4A)
C(51)eSn(1)eO(4A)
O(9)eSn(1)eO(4A)
O(9)eSn(2)eC(39)
O(9)eSn(2)eC(35)
C(39)eSn(2)eC(35)
O(9)eSn(2)eO(8)
C(39)eSn(2)eO(8)
C(35)eSn(2)eO(8)
O(9)eSn(2)eO(10)
C(39)eSn(2)eO(10)
C(35)eSn(2)eO(10)
O(8)eSn(2)eO(10)
11.7(2)
114.0(2)
134.2(3)
74.51(15)
98.3(2)
97.5(2)
84.16(15)
91.1(2)
O(8)eSn(3)eC(43)
O(8)eSn(3)eO(9)
C(43)eSn(3)eO(9)
O(8)eSn(3)eC(57)
C(43)eSn(3)eC(57)
O(9)eSn(3)eC(57)
O(8)eSn(3)eO(7)
C(43)eSn(3)eO(7)
O(9)eSn(3)eO(7)
C(57)eSn(3)eO(7)
O(8)eSn(4)eC(27)
O(8)eSn(4)eC(31)
C(27)eSn(4)eC(31)
O(8)eSn(4)eO(1)
C(27)eSn(4)eO(1)
C(31)eSn(4)eO(1)
O(8)eSn(4)eO(7)
C(27)eSn(4)eO(7)
C(31)eSn(4)eO(7)
O(1)eSn(4)eO(7)
114.2(3)
75.06(15)
99.1(3)
117.7(3)
128.0(4)
96.4(2)
72.43(15)
96.8(3)
147.35(16)
96.0(2)
120.6(3)
114.2(2)
125.0(3)
79.88(15)
96.1(3)
98.5(2)
72.18(15)
95.3(3)
97.6(2)
89.3(2)
147.60(13)
113.0(3)
115.6(3)
130.8(3)
80.39(13)
98.8(2)
96.0(2)
72.20(14)
93.2(3)
158.59(15)
116.4(3)
118.2(3)
125.4(3)
74.96(15)
98.5(3)
97.0(2)
73.01(15)
94.6(2)
94.6(2)
152.55(14)
99.0(3)
147.94(15)
95.9(2)
151.86(15)
96.9(2)
Symmetry transformations used to generate equivalent atoms: A ꢀx, ꢀy, ꢀz.
Symmetry transformations used to generate equivalent atoms: A ꢀx þ 1, ꢀy þ 1, ꢀz.
considerably from 180ꢁ, which indicate that the structures are
distorted trigonal bipyramidal. The distortions are partly due to the
rigid framework of the ladders. Moreover, each carboxylate group
coordinates to an exocyclic Sn atom exclusively in the monodentate
mode to generate a macrocycle containing two ladders (Fig. 3).
The formation of 4e6 represents an example of ladder-type
carboxylates in which the insertion of m2-OR (R ¼ CH3CH2e or
CH3CH2CH2CH2e) group occurs. Crystal structure of 4e6 features
n-Bu2SnO3 trigonal bipyramidal coordination environments with
the two n-Bu groups and one O atom in equatorial positions and the
other two O atoms in axial positions. The axial OeSneO angles
range from 146.67(14) to 158.59(15) for 4e6, and thus deviate
Table 5
Selected bond lengths (Å) and angles (ꢁ) for 5.
Sn(1)eO(2)
Sn(1)eC(25)
Sn(1)eC(29)
Sn(1)eO(7)
Sn(1)eO(1)
Sn(2)eO(2)
Sn(2)eO(3)
Sn(2)eC(45)
Sn(2)eC(41)
Sn(2)eO(1)
2.007(2)
2.115(6)
2.134(5)
2.174(2)
2.207(3)
2.043(2)
2.102(2)
2.126(4)
2.132(4)
2.185(3)
Sn(3)eO(3)
Sn(3)eC(33)
Sn(3)eC(21)
Sn(3)eO(2)
Sn(3)eO(4)
Sn(4)eO(4)
Sn(4)eO(3)
Sn(4)eC(49)
Sn(4)eC(53)
Sn(4)eO(6A)
2.049(2)
2.127(4)
2.131(4)
2.137(2)
2.162(2)
2.059(2)
2.110(2)
2.120(4)
2.120(4)
2.285(2)
a
m2-coordination of eOR. This result can be interpreted in terms of
donor strength competition, in which the eOR groups show higher
donor capacity than the carboxylates group of the HL [34,35].
The Sn2/O8A for 4, Sn1/O8 for 5 and Sn4/O2 for 6 distance is
3.143, 3.192 and 3.092 Å, which is less than the sum of van der
Waals radii (3.68 Å) [32]. Thus, if this weak interaction is considered
sufficiently, the geometry around Sn atom is best described as
skew-trapezoidal bipyramidal geometry.
The O6 for 4, O5A for 5 and O3A for 6 of the carboxylate have
weak interactions with Sn: the bond lengths of Sn3/O6 (3.522 Å)
for 4, Sn4/O5A (3.567 Å) for 5 and Sn1/O3A (3.451 Å) for 6.
Intermolecular Sn/O interactions exist between Sn (Sn3 for 4, Sn4
for 5 and Sn1 for 6) and O (ethanolic oxygen O11B for 4, ethanolic
oxygen O11B for 5 and carbonylic oxygen O5B for 6) at 3.017, 2.903
and 3.393 Å, in which the ethanolic oxygen shows stronger coor-
dination than carbonylic oxygen. The influence of the intermolec-
ular O atoms is so strong that it causes the expansion of the
CeSneC angle [C26eSn3eC22 140.9(2)ꢁ for 4, C49eSn4eC53
138.11(15)ꢁ for 5 and C47eSn1eC51134.2(3)ꢁ for 6]. If these oxygen
atoms can be considered as bonding, each tin atom (Sn3 for 4, Sn4
for 5 and Sn1 for 6) is seven-coordinated.
O(2)eSn(1)eC(25)
O(2)eSn(1)eC(29)
C(25)eSn(1)eC(29)
O(2)eSn(1)eO(7)
C(25)eSn(1)eO(7)
C(29)eSn(1)eO(7)
O(2)eSn(1)eO(1)
C(25)eSn(1)eO(1)
C(29)eSn(1)eO(1)
O(7)eSn(1)eO(1)
O(2)eSn(2)eO(3)
O(2)eSn(2)eC(45)
O(3)eSn(2)eC(45)
O(2)eSn(2)eC(41)
O(3)eSn(2)eC(41)
C(45)eSn(2)eC(41)
O(2)eSn(2)eO(1)
O(3)eSn(2)eO(1)
C(45)eSn(2)eO(1)
C(41)eSn(2)eO(1)
113.9(2)
114.4(2)
131.6(3)
80.04(9)
94.1(2)
O(3)eSn(3)eC(33)
O(3)eSn(3)eC(21)
C(33)eSn(3)eC(21)
O(3)eSn(3)eO(2)
C(33)eSn(3)eO(2)
C(21)eSn(3)eO(2)
O(3)eSn(3)eO(4)
C(33)eSn(3)eO(4)
C(21)eSn(3)eO(4)
O(2)eSn(3)eO(4)
O(4)eSn(4)eO(3)
O(4)eSn(4)eeC(49)
O(3)eSn(4)eC(49)
O(4)eSn(4)eC(53)
O(3)eSn(4)eC(53)
C(49)eSn(4)eC(53)
O(4)eSn(4)eO(6A)
O(3)eSn(4)eO(6A)
C(49)eSn(4)eO(6A)
C(53)eSn(4)eO(6A)
113.11(14)
116.84(14)
130.03(17)
74.48(9)
97.59(13)
94.38(13)
73.37(9)
96.85(13)
98.10(13)
147.77(9)
74.26(9)
110.38(13)
102.51(13)
109.05(13)
101.19(13)
138.11(15)
81.78(9)
97.06(18)
72.53(9)
96.36(19)
94.80(17)
152.56(10)
75.36(9)
119.35(15)
97.25(13)
114.22(15)
100.96(15)
126.15(18)
72.34(10)
147.27(10)
93.94(14)
96.92(15)
In the interesting structures of complex 4 and 5, the ethanolic
oxygen forms weak Sn/O interactions and OeH/O (2.818 Å for 4
and 2.783 Å for 5) hydrogen bonds, which construct the 2D supra-
molecular network structure with each other’s adjacent macrocycle
containing two ladders to afford a novel macrocycle (II) (Fig. 4).
155.96(9)
83.86(13)
88.27(12)
Symmetry transformations used to generate equivalent atoms: A ꢀx þ 1, ꢀy þ 2,
ꢀz þ 1.

2556
D. Du et al. / Journal of Organometallic Chemistry 696 (2011) 2549e2558
Fig. 4. The supramolecular structure of 4 and 5, showing the 2D supramolecular
network structure by intermolecular Sn/O interactions and OeH/O hydrogen bonds.
Parts of the n-butyl groups have been omitted for clarity.
(II) voids of complex 6 allow for two ethanol molecules, but the
obvious interactions [(n-Bu2Sn)2(4,6-L2)O2(OH)(OC2H5)]2 moiety
and the ethanol molecules have not been found. For clarity, the
ethanolic guest molecule is space-filling.
3.3.3. Antitumor activity
Table 7 shows antitumor effects against three cancer cell lines in
different concentrations (0.3, 1, 3, 10, and 30 mg/ml) of complexes
1e6. From the data of Table 7, we can see that the growth inhibition
of all cells to 10 mg/ml solutions of complexes 1e6 are partly the
best. In addition, 0.3 mg/ml of 2 and 4 do not show antitumor effects
against HT1080, the same with 0.3 mg/ml of 4 and 6 to HeLa. In
comparisonwith complexes 1 and 2, 3 is the best antitumoragent for
HeLa (3 > 1 > 2), and so is 1 for HT1080 (1 > 3 > 2) and U87
(1 > 2 > 3). Compared with complexes 4 and 6, 5 is the best anti-
tumor agent for HeLa (5 > 6 > 4), and so is 4 for HT1080 (4 > 6 > 5)
and U87 (4 > 6 > 5). The relative effectiveness of the anti-cancer
activities shows that the different complexes act against the same
Fig. 3. The molecular structures of complexes 4e6 with thermal ellipsoids at 15%
probability level. Solvent molecules have been omitted for clarity.
It is noteworthy that the self-assembly occurs through an
extensive set of intermolecular Sn/O interactions in 6 and helps
the molecules form a 1D infinite chains with another type of a novel
macrocycle (II) having larger cavity (Fig. 5). The novel macrocyclic

D. Du et al. / Journal of Organometallic Chemistry 696 (2011) 2549e2558
2557
Fig. 5. The supramolecular structure of the complex 6, showing the inclusion of solvent molecules within the macrocycle void, macrocyclic network and 1D chain of rings connected
by intermolecular Sn/O interactions. Parts of the n-butyl groups have been omitted for clarity.
It should be pointed out that we tested the effect of ligands
(H2L1e3) alone against each cell line, however, those ligands
exhibited almost no inhibition of cellular proliferation
(IC50 > 300 mg/ml). In addition, fat-solubility of di-n-butyltin oxide
and triphenyltin hydroxide are poor and they are not easily hydro-
lyzed into active ion (n-Bu2Sn2þ and Ph3Snþ), while organic acid
ligand enhances the fat-solubility of organotin carboxylates
[39e41].
Table 7
The in vitro antitumor activities of 1e6 against HeLa, HT1080 and U87 cells.
Drug labeling Dose (
mg/ml) Anticancer activity (%)
HeLa
HT1080
U87
Complex
1
2
3
1
2
3
1
2
3
0.3
1
3
10
11.7 14.5 24.3 6.3 ꢀ2.1 8.9 52.3 40.0 28.2
33.2 26.4 50.4 25.0 19.0 15.3 67.1 55.9 40.0
43.4 38.1 56.9 56.6 42.0 54.6 72.4 67.6 43.1
44.4 44.5 57.6 66.0 65.8 65.5 74.7 73.6 43.7
43.9 43.9 56.8 66.0 65.2 62.5 72.8 73.3 44.2
30
Acknowledgments
Complex
4
5
6
4
5
6
4
5
6
0.3
1
3
10
30
ꢀ2.3 9.1 ꢀ1.4 ꢀ3.1 1.6 0.7 50.9 9.8 6.5
6.5 47.6 ꢀ0.2 10.2 4.1 ꢀ0.4 64.2 31.3 9.5
30.8 52.2 7.3 14.0 2.7 3.6 69.4 40.5 53.8
42.6 56.9 34.2 61.7 17.8 28.8 73.6 42.9 70.2
42.1 55.9 43.8 61.0 22.0 45.3 71.0 43.4 71.2
We acknowledged the Postdoctoral Science foundation of China
(No. 2005038561).
Appendix A. Supplementary data
CCDC 717707, 717708, 717709, 717703, 717706 and 717704
contain the supplementary crystallographic data for complexes
1e6. These data can be obtained free of charge from The Cambridge
Crystallographic Data Centre via www.ccdc.cam.ac.uk/data_
request/cif.
cell with different effects, while the same complex acts against the
different cells also with different effects. The results indicate that
complexes act against cells selectively and the substituent groups of
the ligands have an effect on antitumor activity.
From the derived IC50 values (Table 8), 3 seems to be the most
efficient antitumor agent for HeLa and its antitumor activity is
higher than that of the clinically used cis-platin (IC ¼ 3.50) [36]. 1, 2
and 4 seem to be the most efficient antitumor agents for U87 and
their antitumor activities are higher than that of the clinically used
cis-platin (IC ¼ 2.60 ꢃ 1.00) [37]. Cis-platin cannot kill the HT1080
cancer cell [38], but the complexes 1e6 have an effect on HT1080, so
we can arrive at a conclusion that 1 is best for HT1080, while
antitumor effects of the complexes 2 and 3 are similar, which
indicates that the ligand substituting group has little impact on
HT1080.
Appendix. Supplementary data
Supplementary data related to this article can be found online at
doi:10.1016/j.jorganchem.2011.03.048.
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