Synthesis, crystal structure, and characterization of dimeric tetraorganodistannoxane and two tricyclohexyltin carboxylates

Article abstract of DOI:10.1080/00958972.2010.500665

Three diorganotin(IV) series and triorganotin(IV) complexes, [(C ₆H₁₁)₂Sn]₄(L1)₂O ₂(OH)₂ (1), (C₆H₁₁) ₃Sn(HL₂) (2), and (C₆H₁₁) ₃SnL3 (3) (where HL1 is 2-(4-isopropyl benzoyl) benzoic acid, H ₂L₂ is phthalic acid and HL3 is 2-benzoyl benzoic acid), were synthesized and their crystal structures were determined. There are four crystallographically unique Sn centers in the structure of 1, which consists of a Sn₄O₂(OH)₂ ladder unit, and the ladder consists of four tins held together by two 3-oxygens and two 2-oxygens. The supermolecular motif of 1 is a 2-D structure linked by O-H O hydrogen bonds. The asymmetric unit of 2 contains two crystallographically independent monomers. The supramolecular architecture of 2 is a 2-D layer structure linked by face-to-face - interactions between phenyl rings of adjacent L2 anions. The structure of 3 contains one tricyclohexyltin cation and one L3 anion. The Sn O interactions lead the whole structure to a supramolecular chain. Elemental analysis, infrared, and 1H NMR of 1-3 were investigated and discussed.

Full text of DOI:10.1080/00958972.2010.500665

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Synthesis, crystal structure,
and characterization of dimeric
tetraorganodistannoxane and two
tricyclohexyltin carboxylates
Adama Moussa Sakho a , Dafeng Du a , Wenjie Li a , Shuangshuang
Liu a , Dongsheng Zhu a & Lin Xu a
a Department of Chemistry , Northeast Normal University ,
Changchun 130024, P.R. China
Published online: 13 Jul 2010.
To cite this article: Adama Moussa Sakho , Dafeng Du , Wenjie Li , Shuangshuang Liu ,
Dongsheng Zhu & Lin Xu (2010) Synthesis, crystal structure, and characterization of dimeric
tetraorganodistannoxane and two tricyclohexyltin carboxylates, Journal of Coordination Chemistry,
63:13, 2317-2327, DOI: 10.1080/00958972.2010.500665
To link to this article: http://dx.doi.org/10.1080/00958972.2010.500665
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Journal of Coordination Chemistry
Vol. 63, No. 13, 10 July 2010, 2317–2327
Synthesis, crystal structure, and characterization of dimeric
tetraorganodistannoxane and two tricyclohexyltin carboxylates
ADAMA MOUSSA SAKHO, DAFENG DU, WENJIE LI,
SHUANGSHUANG LIU, DONGSHENG ZHU* and LIN XU
Department of Chemistry, Northeast Normal University, Changchun 130024, P.R. China
(Received 4 January 2010; in final form 1 April 2010)
Three diorganotin(IV) series and triorganotin(IV) complexes, [(C6H11)2Sn]4(L1)2O2(OH)2 (1),
(C6H11)3Sn(HL2) (2), and (C6H11)3SnL3 (3) (where HL1 is 2-(4-isopropyl benzoyl) benzoic acid,
H2L2 is phthalic acid and HL3 is 2-benzoyl benzoic acid), were synthesized and their crystal
structures were determined. There are four crystallographically unique Sn centers in the
structure of 1, which consists of a Sn4O2(OH)2 ladder unit, and the ladder consists of four tins
held together by two m3-oxygens and two m2-oxygens. The supermolecular motif of 1 is a 2-D
structure linked by O–H ꢀ ꢀ ꢀ O hydrogen bonds. The asymmetric unit of 2 contains two
crystallographically independent monomers. The supramolecular architecture of 2 is a 2-D
layer structure linked by face-to-face ꢀ–ꢀ interactions between phenyl rings of adjacent L2
anions. The structure of 3 contains one tricyclohexyltin cation and one L3 anion. The Sn ꢀ ꢀ ꢀ O
interactions lead the whole structure to a supramolecular chain. Elemental analysis, infrared,
and 1H NMR of 1–3 were investigated and discussed.
Keywords: Organotin; Tetraorganodistannoxane; Synthesis; Crystal structure; Coordination
polymer
1. Introduction
Organotin carboxylate derivatives have antitumor activity, rich structural chemistry [1],
and wide use as PVC stabilizers, as catalysts, and in polyurethane polymerization [2].
The structural studies of organotin(IV) compounds of carboxylic acids are of growing
interest because there are many possible bonding interactions between oxygen of
carboxyl and tin. Studies on diorganotin(IV) or triorganotin(IV) compounds of
carboxylic acid [3] revealed new structural types which may lead to compounds with
different activities. However, dicyclohexyltin and tricyclohexyltin carboxylates have
not been reported [4]. We recently reported some organotin compounds with
different carboxylates. As the continuation of this investigation, we have now synthe-
sized three organotin carboxylates: [(C6H11)2Sn]4(L1)2O2(OH)2 (1), (C6H11)3Sn(HL2)
(2), and (C6H11)3SnL3 (3) (HL1 ¼ 2-(4-isopropyl benzoyl) benzoic acid; H2L2 ¼ phthalic
acid; HL3 ¼ 2-benzoyl benzoic acid). The 1H NMR and FT-IR spectroscopies
characterize 1–3.
*Corresponding author. Email: zhuds206@nenu.edu.cn
Journal of Coordination Chemistry
ISSN 0095-8972 print/ISSN 1029-0389 online ß 2010 Taylor & Francis
DOI: 10.1080/00958972.2010.500665

2318
A.M. Sakho et al.
2. Experimental
2.1. Materials and methods
Phthalic acid (HL2) was purchased from commercial sources and used without
purification; the solvents were purified before use by standard procedures. The melting
points were obtained in open capillaries and are uncorrected. Elemental analyses were
performed with a Perkin-Elmer PE 2400 CHN instrument and gravimetric analysis was
1
performed for Sn. H NMR spectra were recorded in CDCl3 on a Varian Mercury
300 MHz spectrometer. Infrared (IR) spectra using KBr pellets were recorded on an
Alpha Centauri FI/IR spectrometer (400–4000 cmꢁ1).
X-ray crystallographic data for 1–3 were recorded on a Bruker CCD Area detector
image plate diffractometer using the !/’ scan technique with Mo-Kꢁ radiation
˚
(ꢂ ¼ 0.71073 A). Absorption corrections were applied using multi-scan techniques [5].
The structures were solved by direct methods with SHELXS-97 [4] and refined by full-
matrix least squares with SHELXL-97 [6] within WINGX [7]. All non-hydrogen atoms
were refined with anisotropic temperature parameters. Hydrogens were refined as rigid
groups. The detailed crystallographic data and structure refinement parameters for 1–3
are summarized in table 1.
2.2. Syntheses
2.2.1. Synthesis of 2-(4-isopropylbenzoyl) acid (HL1). Phthalic anhydride (5.92 g,
0.04 mol), anhydrous aluminum chloride (10.67 g, 0.08 mol), and dry isopropyl benzene
(60 mL) were added to a three-neck flask. The mixture was stirred for 6 h at 50ꢂC and
transferred into a beaker. After cooling to room temperature it was hydrolyzed with
aqueous HCl (20%) to obtain a white solid which was collected by filtration. The solid
was dissolved in 20% aqueous NaOH and the excess solvent was removed by
hydrodistillation. The distillate obtained was acidified with 20% HCl and the solid got
precipitated. Then the filtrate was washed with water; the solid thus obtained was
recrystallized from the ethanol before a pure white powder was obtained. The yield was
63%, m.p. 118–120ꢂC, IR (KBr, cmꢁ1): ꢃsym(COO) 1420, 1569; ꢃasym(COO) 1599, 1614;
1
ꢃ(O–H) 3440; H NMR (CDCl3) ꢄ: 1,24 (d, 6H, –CH3), 3.05 (m, 1H, –CH), 7.26–8.11.
(m, 8H, Ar–H), 11.63 (s, 1H, –COOH). Anal. Calcd for C17H16O3 (%): C, 76.10; H,
6.01. Found (%): C, 76.03; H, 5.96.
2.2.2. Synthesis of 2-benzoyl benzoic acid (HL3). HL3 was prepared by the same
procedure as HL1; in which the mixture of phthalic anhydride (5.92 g, 0.04 mol),
anhydrous aluminum chloride (10.67 g, 0.08 mol), and dry benzene (60 mL) gave a pure
white powder whose yield was 58%, m.p. 138–140ꢂC, IR (KBr, cmꢁ1): ꢃsym(COO) 1413,
1555; ꢃas(COO) 1584, 1606; ꢃ(O–H) 3445; 1H NMR (CDCl3) ꢄ: 7.26–8.13 (m, 9H,
Ar–H), 11.13 (s, 1H, –COOH). Anal. Calcd for C14H10O3 (%): C, 74.33; H, 4.46. Found
(%): C, 74.26; H, 4.42.
2.2.3. Synthesis of [(C6H11)2Sn]4(L1)2O2(OH)2] (1). A mixture of dicyclohexyltin
oxide (0.301 g, 1 mmol) and HL1 (0.268 g, 1 mmol) in dry benzene (40 mL) was refluxed

Tricyclohexyltin carboxylates
2319
Table 1. Crystal data and details of structure refinement parameters for 1–3.
1
2
3
Empirical formula
Formula weight
Crystal size (mm3)
Crystal system
Space group
C
1740.54
0.33 ꢃ 0.24 ꢃ 0.21
Monoclinic
P21/n
82H120O10Sn4
C20H37O4Sn
532.25
0.36 ꢃ 0.30 ꢃ 0.28
Monoclinic
P21/c
C32H42O3Sn
593.35
0.32 ꢃ 0.27 ꢃ 0.23
Monoclinic
P21/n
ꢂ
˚
Unit cell dimensions (A, )
a
b
c
12.4789(11)
17.2594(15)
19.6118(17)
100.7130(10)
4150.3(6), 2
1.393
1.242
1784
1.06–24.67
20,527
13,272 [R(int) ¼ 0.0467]
R1 ¼ 0.0567,
wR2 ¼ 0.1018
R1 ¼ 0.1288,
wR2 ¼ 0.1276
0.980
19.1159(11)
15.0730(9)
17.9044(10)
106.1730(10)
4954.7(5), 8
1.427
1.060
2200
1.75–26.04
27,313
9750 [R(int) ¼ 0.0361]
R1 ¼ 0.0369,
wR2 ¼ 0.0812
R1 ¼ 0.0611,
wR2 ¼ 0.0913
1.016
13.966(2)
14.399(2)
14.606(2)
93.101(2)
2932.8(8), 4
1.344
ꢅ
Volume (A ), Z
3
˚
Calculated density (g cmꢁ3
)
Absorption coefficient (mmꢁ1
F(000)
)
0.900
1232
ꢆ range for data collection (ꢂ)
Reflections collected
Unique reflections
1.99–25.01
14,618
5144 [R
¼ 0.0543]
(int)
Final R indices [I 4 2ꢇ(I )]
R1 ¼ 0.0476,
wR2 ¼ 0.0986
R1 ¼ 0.0975,
wR2 ¼ 0.1164
1.001
R indices (all data)
Goodness-of-fit on F 2
Largest differenꢁce3 peak
0.493 and ꢁ0.413
1.010 and ꢁ0.446
0.521 and ꢁ0480
˚
and hole (e A
)
for 8 h in a Dean–Stark separator. After cooling to room temperature, the solvent was
gradually removed by evaporation under vacuum until solid product was obtained. The
resulting solid was then recrystallized from ethanol/water to give buff crystals of 1. The
yield was 67%, m.p. 188–190ꢂC. IR (KBr, cmꢁ1): ꢃ(C–H) 2935, 2920, 2864; ꢃ(Sn–O–Sn)
482, 422; ꢃ(Sn–C) 541; ꢃsym(COO) 1376, 1432; ꢃas(COO) 1588, 1650. 1H NMR (CDCl3)
ꢄ: 1.23–1.94 (m, 88H, CH2, SnC6H11, 12H, –CH3), 2.04 (s, 2H, Sn–OH–Sn), 3.1 (m, 2H,
–CH), 7.15–7.65 (m, 16H, Ph). Anal. Calcd for C82H120O10Sn4 (%): C, 56.58; H, 6.95;
Sn, 27.28. Found (%): C, 56.53; H, 6.89; Sn, 27.24.
2.2.4. Synthesis of (C6H11)3Sn(HL2) (2). Complex 2 was prepared by the same
procedure as 1 in which a mixture of tricyclohexyltin hydroxide (0.385 g, 1 mmol) and
phthalic acid (H2L2) (0.166 g, 1 mmol) was refluxed for 8 h in a Dean–Stark separator.
After cooling to room temperature, the solvent was gradually removed by evaporation
under vacuum until solid product was obtained. The resulting solid was then
recrystallized from ethanol/water to give buff crystals of 2 in 58% yield, m.p.
170–172ꢂC. IR (KBr, cmꢁ1): ꢃ(Sn–O–Sn) 455, 416; ꢃ(Sn–C) 549; ꢃsym(COO) 1351, 1443;
ꢃas(COO) 1590, 1663. 1H NMR (CDCl3) ꢄ: 1.25–1.96 (m, 33H, CH2, SnC6H11),
7.19–7.96 (m, 4H, Ar–H). Anal. Calcd for C26H37O4Sn (%): C, 58.66; H, 7.01; Sn,
22.30. Found (%): C, 58.57; H, 7.11; Sn, 22.35.

2320
A.M. Sakho et al.
2.2.5. Synthesis of (C6H11)SnL3 (3). Complex 3 was prepared by the same procedure
as 1 using a mixture of tricyclohexyltin hydroxide (0.385 g, 1 mmol) and HL3 (0.226 g,
1 mmol) in 53% yield, m.p. 138–140ꢂC. IR (KBr, cmꢁ1): ꢃ(Sn–O–Sn) 454, 412, ꢃ(Sn–C)
634; ꢃsym(COO) 1350, 1440; ꢃas(COO) 1584, 1663. 1H NMR (CDCl3) ꢄ: 1.23–1.93
(m, 33H, CH2, SnC6H11), 7.26–7.76 (m, 9H, Ar–H). Anal. Calcd for C32H42O3Sn (%):
C, 64.77; H, 7.13; Sn, 20.00. Found (%): C, 64.72; H, 7.07; Sn, 20.08.
3. Results and discussion
3.1. Syntheses
The synthetic procedures are shown in scheme 1.
3.2. IR spectra
In the IR spectra of 1–3, the absence of a broad band at 2500–3550 cmꢁ1, which appears
in the spectra of the free ligand as ꢃ(O–H), indicates the formation of metal–ligand
bonds. The difference of Dꢃ(ꢃas(COO) ꢁ ꢃsym(COO)) is used to determine the nature of
bonding of tin carboxylate complexes [8]. This difference in Dꢃ between asymmetric and
symmetric absorption frequencies below 200 cmꢁ1 indicates that the carboxylate is
bidentate, while greater than 200 cmꢁ1 indicates unidentate carboxylate [9]. The
ꢃas(COO) and ꢃsym(COO) vibrations are 1588, 1650 and 1376, 1432 cmꢁ1 for 1; 1590,
H
O
O
Benzene
OH
OH
S
n
Sn
O
SnO
O
O
O
Refluxing
O
O
O
Sn
S
n
O
O
H
HL
OH
1
1
OH
O
O
OH
O
O
Benzene
Refluxing
Sn
O
O
Sn
O
O
SnOH
OH
n
H 2 L 2
2
OH
O
Benzene
O
SnOH
O
Sn
Refluxing
O
O
3
HL 3
Scheme 1. The synthesis procedure of 1–3.

Tricyclohexyltin carboxylates
2321
1663 and 1351, 1443 cmꢁ1 for 2; and 1584, 1663 and 1350, 1440 cmꢁ1 for 3. The
differences of D[ꢃas(COO) ꢁ ꢃsym(COO)] between these frequencies for 1–3 are close to
those found for a unidentate carboxylate (218 and 212 cmꢁ1 for 1; 239 and 220 cmꢁ1 for
2; and 208 and 223 cmꢁ1 for 3), which was confirmed by X-ray structural analyses.
Bands at 477 and 419 cmꢁ1 are assigned to ꢃ(Sn–O–Sn), indicating the formation of
Sn–O–Sn bridges [9]. The absorption bands at 536, 585, and 549 cmꢁ1 for 1–3 are
assigned to ꢃ(Sn–C) stretching modes [10].
3.3. 1H NMR spectra
1
In H NMR spectra of the free ligands, single resonances are observed at 11–12 ppm,
1
which are absent when the carboxylate coordinates with Sn. H NMR of 1–3 show a
multiplet at 1.23–1.96 ppm due to the cyclohexyl protons, and the protons on the
phenyls of 1–3 show multiplets at 7.15–7.96 ppm.
3.4. Crystal structures
Detailed crystallographic data and structural refinement parameters for 1–3 are
summarized in table 1 with selected bond lengths and angles in table 2.
3.4.1. Structure of [(Cy2Sn)4(L1)2)O2(OH)2]. As shown in figure 1, the structure of 1
consists of a Sn4O2(OH)2 ladder unit. Four tin atoms are almost coplanar, with the
˚
largest deviation from the Sn4O2(OH)2 ladder plane being 0.0149 A. Each ladder
consists of four tin centers held together by two m3-oxygens. According to their
coordination environments, the four tins can be divided into two types. Sn1 and Sn4,
bonded to one m3-oxygen, one m2-oxygen, and one oxygen derived from the carboxylate
ꢂ
˚
Table 2. Selected bond lengths (A) and angles ( ) for 1–3.
1
Sn1–O5
Sn2–O2
Sn2–O3
2.171(9)
2.024(8)
2.130(8)
Sn3–O3
Sn3–O2
Sn4–O7
2.070(7)
2.180(8)
2.197(9)
O5–Sn1–O1
O2–Sn1–C41
O2–Sn1–C51
C41–Sn1–C51
O1–Sn2–O3
O2–Sn2–C61
O2–Sn2–C71
C61–Sn2–C71
155.4(3)
113.4(6)
112.6(6)
131.8(8)
147.7(3)
122.9(5)
115.3(6)
121.6(7)
O4–Sn3–O2
146.4(3)
118.2(5)
121.4(6)
120.5(7)
155.1(3)
117.7(5)
110.0(6)
130.4(7)
O3–Sn3–C81
O3–Sn3–C91
C81–Sn3–C91
O7–Sn4–O4
O3–Sn4–C101
O3–Sn4–C111
C101–Sn4–C111
2
Sn1–C41
Sn2–C71
2.149(3)
2.162(3)
Sn1–O1
Sn2–O7#3
2.479(2)
2.284(2)
O3–Sn1–O1
171.74(8)
O7#3–Sn2–O5
171.60(9)
2.150(7)
123.2(6)
3
Sn1–O1
Sn1–C41
2.132(4)
2.144(5)
Sn1–C31
O1–Sn1–C31
93.0(3)
O2–C1–O1
Symmetry code: #3 x, ꢁy þ 5/2, z þ 1/2.

2322
A.M. Sakho et al.
Figure 1. A view of the molecular structure of 1 showing the atomic numbering scheme. Hydrogen atoms
have been omitted for clarity.
HL1, can be regarded as type 1; Sn2 and Sn3, bonded to two m3-oxygens and one
m3-oxygen, can be regarded as type 2. All of the tin atoms are five-coordinate with two
cyclohexyl groups and three oxygens, resulting in a cis-(C6H11)2SnO3 trigonal–
bipyramidal coordination environment with two cyclohexyl groups and one oxygen
in equatorial positions. The angle range of O–Sn–O is 146.4(3)–155.4(3)ꢂ, deviating
considerably from 180ꢂ, which indicates that the structure is distorted. For Sn1, the
trigonal plane is defined by C41, C51, and O2 with axial positions occupied by O5 and
O1; the trigonal plane for Sn2 is defined by C61, C71, and O2 with axial positions
occupied by O3 and O1. For Sn3, C81, C91, and O3 are equatorial and O4 and O2 are
axial. For Sn4, C111, C101, and O3 are equatorial and O7 and O4 are axial. Each
˚
exocyclic Sn is also coordinated by monodentate carboxylate Sn1–O5 ¼ 2.171(9) A and
˚
Sn4–O7 ¼ 2.197(9) A.
Complex 1 displays a ladder-type structure that is analogous to the structure of
symmetric distannoxanes [11]. The central cyclic four-membered Sn2O2 core of 1 is
linked to two terminal Cy2Sn entities through m3-oxos O2 and O3, and Sn–O bond
˚
˚
˚
lengths are Sn2–O2 ¼ 2.024(8) A; Sn3–O2 ¼ 2.180(8) A; Sn2–O3 ¼ 2.130(8) A; and Sn3–
˚
O3 ¼ 2.070(7) A. The four tin centers are held together by m3 O2 and O3. Sn2 and Sn3
are each bonded to two m3-oxos and one m2-oxo. Sn1 and Sn4 are each bonded to one
m3-oxo and one m2-oxo, and are asymmetrically bridged by HL1 through O5 and O7.
The central Sn2O2 core is linked to the two outer Sn2O2 rings resulting in a ladder-type
structure as shown in figures 1 and 2. The two oxygens of the central cyclic unit are
tridentate, linking three Sn atoms (two endocyclic and one exocyclic). O6 and O8 of the
˚
carboxylate have weak interactions with Sn; the bond lengths of Sn1 ꢀ ꢀ ꢀ O6 (2.988 A)
˚
˚
and Sn4 ꢀ ꢀ ꢀ O8 (3.090 A) are less than the sum of the Van der Waals radii (3.58 A) [12]
(figure 3). Weak O–H ꢀ ꢀ ꢀ O interactions exist between hydroxy hydrogen and
˚
carboxylate oxygen (O(1)–H(1) ꢀ ꢀ ꢀ O(10)#1 of 2.06 A and O(4)–H(4) ꢀ ꢀ ꢀ O(9)#2 of
˚
2.35 A). These interactions lead 1 to form a 2-D supramolecular framework (figure 4).
Detailed O–H ꢀ ꢀ ꢀ O hydrogen bond parameters are listed in table 3.

Tricyclohexyltin carboxylates
2323
Figure 2. Repeating fragment ladder-type structure in the polymeric layer of 1. For clarity, only the first
carbons of the cyclohexyl linked to Sn are shown.
Figure 3. Repeating unit of 1, including Sn ꢀ ꢀ ꢀ O interactions shown by orange dotted lines. Selected bond
˚
˚
distances: [Sn1 ꢀ ꢀ ꢀ O6 ¼ 2.988 A and Sn4 ꢀ ꢀ ꢀ O8 ¼ 3.090 A].
3.4.2. Molecular and crystal structure of 2. The structure of 2 (figure 5) contains two
independent units with similar conformations and only small differences in bond
lengths and angles (table 2). Each unit contains two different carboxylates, one L2 anion
and one benzoic anion. The tins form distorted trans-O2SnC3 trigonal bipyramidal
with three cyclohexyl groups in the equatorial plane [13]. Sn–C distances lie in the
˚
range 2.149(3)–2.162(3) A and Sn–O bond lengths involving carboxyl oxygen are
˚
˚
˚
˚
2.284(2)–2.479(2) A [Sn1–O1 ¼ 2.479(2) A; Sn1–O3 ¼ 2.242(2) A; Sn2–O5 ¼ 2.339(2) A;
˚
and Sn2–O7#3 ¼ 2.284(2) A]. Weak distortion angle observed can be attributed to the
presence of steric interactions by three cyclohexyl groups attached to Sn1 and Sn2
(shown by the first carbon of the cyclohexyl groups), giving angles of O3–Sn1–O1
and O7#3–Sn2–O5 [171.74(8)ꢂ and 171.60(9)ꢂ, respectively]. The carboxylate oxygens of
L2 anions and benzoic anions are monodentate. Tricyclohexyltin groups are linked

2324
A.M. Sakho et al.
Figure 4. The 2-D network connected by intermolecular OꢁHꢀ ꢀ ꢀO interactions. The hydrogen atoms
(except H1 and H4) and cyclohexyl groups have been omitted for clarity.
Table 3. Hydrogen bonds for 1.
DꢁH ꢀ ꢀ ꢀ A (ꢂ)
169.8
133.7
˚
˚
˚
DꢁH ꢀ ꢀ ꢀ A
DꢁH (A)
H ꢀ ꢀ ꢀ A (A)
D ꢀ ꢀ ꢀ A (A)
O(1)–H(1) ꢀ ꢀ ꢀ O(10)#1
O(4)–H(4) ꢀ ꢀ ꢀ O(9)#2
0.75
0.76
2.06
2.35
2.922(12)
2.809(13)
#1: ꢁx þ 1, yꢁ1/2, ꢁzꢁ1; #2: ꢁx þ 1, y þ 1/2, ꢁz.
to L2 via O3 for Sn1, O5 for Sn2; and are linked to benzoic anions via O1 for Sn1, O7#3
for Sn2. As shown in figure 5, the L2 anions link Sn1 and Sn2 tricyclohexyltin groups to
two polymeric chains. Face-to-face ꢀ–ꢀ interactions between the phenyl rings of
˚
adjacent L2 anions are observed with a face-to-face distance of 3.612 A (figure 6). The
supramolecular architecture of 2 is a 2-D layer structure.
3.4.3. Molecular and crystal structures of 3. The structure of 3 contains one
tricyclohexyltin cation and one L3 anion (figure 7). The tin has distorted tetrahedral
geometry with bond angles of 93.0(3)ꢂ to 123.2(6)ꢂ, the carboxylate oxygen of L3
˚
coordinates monodentate to tin giving a Sn1–O1 distance of 2.132(4) A. The Sn–C bond
˚
lengths are in the range 2.144(5) to 2.150(7) A, within the normal literature values [14].

Tricyclohexyltin carboxylates
2325
Figure 5. Repeating motif of the two independent structures of 2.
Figure 6. The 2-D supramolecular network of 2 formed by ꢀ – ꢀ stacking interactions shown by blue dotted
lines. Cyclohexyl groups have been omitted for clarity.

2326
A.M. Sakho et al.
Figure 7. Molecule structure of 3 showing atomic numbering scheme. Hydrogen atoms have been omitted
for clarity.
Figure 8. Polymeric chain of 3 formed by intramolecular weak O ! Sn interactions.
˚
The Sn ꢀ ꢀ ꢀ O interaction between O2 and Sn1 (at a distance of 2.867 A) was smaller than
˚
the sum of Van der Waals radii 3.73 A [15]. The structure of 3 is one of the two major
motifs for R0CO2SnR3 [16]. Intermolecular Sn ꢀ ꢀ ꢀ O interactions exist between Sn1 and
˚
O3 at 3.060 A. These Sn ꢀ ꢀ ꢀ O interactions lead the whole structure to a supramolecular
chain, as shown in figure 8.
Supplementary material
CCDC-769210, 769211, and 769212 contain supplementary crystallographic data for
1–3. The data can be obtained free of charge from the Cambridge Crystallographic
Data Center via www.ccdc.cam.ac.uk/data–request.cif.

Tricyclohexyltin carboxylates
2327
Acknowledgments
We acknowledge the support from Postdoctoral Science Foundation, P.R. China
(No. 2005038561).
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