Tri-n-butyltin carboxylate derivatives of para-substituted phenyl-ethanoic acids: Synthesis, characterization and X-ray structure determination

Article abstract of DOI:10.1016/j.jorganchem.2004.06.052

The tributyltin esters of 4-(ethyl)-phenyl-ethanoic acid and 4-(isopropyl)-phenyl-ethanoic acid have been prepared as model compounds of the repeating unit of the related stannylated polystyrenic derivatives. Both the products were fully characterized by proton and carbon NMR two-dimensional techniques. FT-IR spectra show in the solid state carboxylated moieties bridging R 3 Sn groups with the metal atom expanding its coordination number, this structure being destroyed in solution. The supramolecular arrangement of the products in the solid state has been investigated by X-ray diffraction, which confirms the pentacoordination at tin in both the products, and indicates a different spatial arrangement of the alkylated aryl groups, as evidenced also by the slightly different thermal properties.

Full text of DOI:10.1016/j.jorganchem.2004.06.052

Journal of Organometallic Chemistry 689 (2004) 3301–3307
www.elsevier.com/locate/jorganchem
Tri-n-butyltin carboxylate derivatives of para-substituted
phenyl-ethanoic acids: synthesis, characterization and X-ray
structure determination
a,
a
a
Luigi Angiolini *, Daniele Caretti , Laura Mazzocchetti ,
a
Elisabetta Salatelli , Cristina Femoni
b
a
`
Dipartimento di Chimica Industriale e dei Materiali, Universita di Bologna, Viale Risorgimento 4, 40136 Bologna, Italy
b
`
Dipartimento di Chimica Fisica ed Inorganica, Universita di Bologna, 40136 Bologna, Italy
Received 21 April 2004; accepted 28 June 2004
Available online 11 September 2004
Abstract
The tributyltin esters of 4-(ethyl)-phenyl-ethanoic acid and 4-(isopropyl)-phenyl-ethanoic acid have been prepared as model com-
pounds of the repeating unit of the related stannylated polystyrenic derivatives. Both the products were fully characterized by pro-
ton and carbon NMR two-dimensional techniques. FT-IR spectra show in the solid state carboxylated moieties bridging R3Sn
groups with the metal atom expanding its coordination number, this structure being destroyed in solution. The supramolecular
arrangement of the products in the solid state has been investigated by X-ray diffraction, which confirms the pentacoordination
at tin in both the products, and indicates a different spatial arrangement of the alkylated aryl groups, as evidenced also by the
slightly different thermal properties.
ꢀ 2004 Elsevier B.V. All rights reserved.
Keywords: Tin coordination; Triorganotin carboxylate; X-ray diffraction; NMR spectroscopy; Supramolecular structure
1. Introduction
functionalities to a macromolecular chain [8] so as to
slower or prevent the release of tin in the environment
[9].
Usually, the synthesis of polymeric derivatives is
accompanied by the preparation of low molecular
weight model compounds resembling the organometallic
repeating unit, in order to compare their properties, and
hence the influence of the macromolecular chain on the
behaviour of the organometal moiety.
In the recent years organotin materials have gained
relevant interest in several research fields [1]. Apart from
academic concern related to fundamental research, tin
derivatives are widely used as components for antifoul-
ing paints [2–4], as catalysts [5] as well as anti-tumour
drugs [6] and ion carriers in electrochemical membrane
building [7].
Generally, tin derivatives suffer of some toxicity and
applications involving tin leaching should be improved,
or even avoided. In order to minimize this drawback,
successful results may be obtained by anchoring tin
In the course of our current investigation [10] on the
synthesis and characterization of poly(styrene) deriva-
tives, useful for electrochemical applications, possessing
the general structure depicted in Chart 1, we have pre-
pared the 4-(ethyl)-phenyl-ethanoic acid tributyltin ester
(III) and 4-(isopropyl)-phenyl-ethanoic acid tributyltin
ester (VI) (Chart 3) as models for the stannylated styr-
enic repeating unit.
*
Corresponding author. Tel./fax: +39-051-2093687.
E-mail addresses: angiolin@ms.fci.unibo.it, luigi.angiolini@uni-
bo.it (L. Angiolini).
0022-328X/$ - see front matter ꢀ 2004 Elsevier B.V. All rights reserved.
doi:10.1016/j.jorganchem.2004.06.052

3302
L. Angiolini et al. / Journal of Organometallic Chemistry 689 (2004) 3301–3307
2. Results and discussion
CH
CH2
CH
CH2
n
1-n
Tri-n-butyltin carboxylates can be obtained in several
ways [12], the most important being a direct esterification
of the carboxylic acid with bis-tributyltin oxide (BTBTO).
Indeed, using toluene as solvent, the water produced in
the reaction can be easily taken off by azeotropic distilla-
tion and the product yield is nearly quantitative.
CH2
COOSnBu3
As depicted in Chart 3, we applied this method to the
preparation of 4-(ethyl)-phenyl-ethanoic acid tributyltin
ester (III) starting from the corresponding carboxylic
acid (II), obtained in turn by catalytic selective hydro-
genation of the commercial unsaturated derivative (I),
an useful monomer for the synthesis of polymeric com-
pounds having III as the repeating unit. Although the
esterification reaction is readily carried out, some unre-
acted BTBTO can be difficult to be removed because of
complexation between tin and carboxylic moieties, thus
requiring repeated crystallizations of the reaction prod-
uct with consequent reduction of yield. For this reason,
despite the reaction is very effective and easy to perform,
we used a different approach for the synthesis of 4-(iso-
propyl)-phenyl-ethanoic acid tributyltin ester (VI). Since
it is known that organotin halides can react with metal-
lic carboxylate [13], we used the sodium salt of 4-(iso-
propyl)-phenyl-ethanoic acid (V) and tri-n-butyltin
chloride as reactants for the preparation of VI. The
carboxylic acid V can be prepared quenching with car-
bon dioxide the Grignard reagent obtained form 4-iso-
propyl-benzylchloride (IV) and magnesium.
Chart 1.
It is known [11] that organotin carboxylates can ex-
ist in at least two different forms (Chart 2). Usually
the first one, where the tin atom is tetracoordinated,
is adopted in diluted solution, as evidenced by both
Sn NMR (d ꢀ 100 ppm for tributyltin derivatives)
and infrared spectroscopy (band close to 1650 cmÀ1
related to the carbonyl stretching of organotin
carboxylate).
Pentacoordinated tin can be observed in concentrated
solutions or in the solid state, as shown by the resonance
at d ꢀ À50 ppm in the Sn NMR spectrum and the IR
absorption band at ca. 1570 cmÀ1 attributed to the car-
bonyl interacting with tin so as to expand its coordina-
tion number.
In some cases tin exhibits both tetra- and pentacoor-
dination, in particular in polymeric materials where, in
the solid state, the macromolecular chain is unable to as-
sume a conformation involving sufficiently extended
pentacoordinated structures. The extent of this behav-
iour is related to both structural parameters of the pol-
ymer itself and to the concentration of stannylated units
[8]. Similar results are also obtained when the substitu-
ents at tin are particularly hindering and prevent, for
sterical reasons, the establishment of a pentacoordinated
form.
Aim of the present paper is therefore to investi-
gate the structure of model compounds III and VI
by using the X-ray diffraction technique in order to
better understanding the behaviour of the related poly-
meric derivatives. Particular attention will be focused
not only to tin coordination, but also to the superstruc-
ture of the aggregates resulting from intermolecular tin
coordination.
Model compounds III and VI were both character-
ized by proton and carbon NMR spectroscopy.
In the high field section of the 13C NMR spectra
recorded in CDCl3, apart from the expected carbon
H2
O(SnBu3)2
Pd/C
CH2
CH2
CH2
COOH
COOH
COOSnBu3
II
I
III
EtONa
Mg
O
CO2
Bu3SnCl
R'
R
Bu
Sn
Bu
Sn
CH2
CH2
O
CH2Cl
C
COOH
COOSnBu3
O
Sn
O
O
O
Bu
Bu
Bu
Bu
Chart 2.
Bu
Bu
Bu
IV
V
VI
Chart 3.

L. Angiolini et al. / Journal of Organometallic Chemistry 689 (2004) 3301–3307
3303
resonances, some satellite bands appear, resulting from
the coupling between 13C and tin (both 117Sn and
119Sn isotopes) and related to the proximity to tin by
the C atoms of n-butyl group, while no coupling is ob-
served between tin and the carbonyl or benzylic carbon.
In particular for compounds III and VI it is possible to
1
observe J(13C, 117Sn/119Sn) = 343/357 and 342/356 Hz
(Table 1), respectively, which are values typical of a
pseudo-tetrahedral arrangement around tin atom [14].
In order to unambiguously assign the 13C chemical
shift values, a combination of two-dimensional NMR
techniques has been used: a gCOSY spectrum showing
cross peaks correlating the mutually coupled protons
and, once this pattern is established, a gHSCQ sequence
allowing the attribution of the carbon atoms.
Upon passing from the carboxylic acids to the corre-
sponding tri-n-butyl derivatives, the disappearance of
the IR carboxyl stretching band centred at 1700 cmÀ1
À1
and new bands at 1572 and 1386 cm
for III, and at
1590 and 1380 cmÀ1 for VI, related to organotin carb-
oxylate are observed. Such new bands are visible only
in the solid state IR and are typical of pentacoordina-
tion at tin due to interaction with carbonyl groups; this
is also confirmed by the Dt difference between the fre-
quencies of asymmetrical and symmetrical stretching
vibrations of the carboxyl moiety (186 and 210 cmÀ1
for III and VI, respectively). These values are close to
those reported [15] for tin in the ionic form, and support
the hypothesis of a structure involving bridged carboxy-
late groups located between planar SnR3 groups with
pentacoordinated tin, having a trigonal bipyramidal
geometry, as formerly depicted in Chart 2.
Fig. 1. ORTEP plot of two adjacent molecules of compound III
belonging to the same chain and interacting through carbonyl oxygen
atom.
The IR spectra recorded in dilute chloroform solu-
tion show the presence of new bands at nearly 1645
and 1355 cmÀ1, attributed to the tetracoordinated form
of the organotin carboxylate since the bridging by carb-
oxylic groups is broken at the coordination bond upon
interaction with the solvent. As expected, the difference
between the asymmetrical and symmetrical carbonyl
stretching vibrations is now higher, i.e. Dt = 291 and
289 cmÀ1, respectively, and closer to typical values of
an organic ester.
Table 1
119Sn NMR data (chemical shifts expressed in ppm) and nJ(13C,
117Sn/119Sn) coupling constants evaluated from 13C NMR spectra
(expressed in Hz) for compounds III and VI in CDCl3 and C6D6
III
VI
CDCl3
C6D6
CDCl3
C6D6
d(119Sn)
109
97
110
98
1J(13C, 117Sn/119Sn)
2J(13C, 117Sn/119Sn)a
3J(13C, 117Sn/119Sn)a
a
343/357
63
20
348/364
64
22
342/356
62
20
344/360
63
21
Fig. 2. ORTEP plot of two adjacent molecules of compound VI
belonging to the same chain and interacting through carbonyl oxygen
atom.
A single approximate value is given when the coupling with 119Sn
and 117Sn is unresolved.

3304
L. Angiolini et al. / Journal of Organometallic Chemistry 689 (2004) 3301–3307
Fig. 3. Single chain structure of organotin carboxylate III as determined by X-ray diffraction.
drance appears to originate a different arrangement of
the aryl groups along the chains. More precisely, in
the case of III the aryl groups bearing the ethyl substit-
uent are in cis position to one another, with respect to
the plane containing oxygen and tin atoms, as evidenced
from the view along the polymeric propagation axis
(Fig. 4), whereas in VI a trans arrangement of the iso-
propyl substituted aryl groups is observed (Fig. 5).
However, the different structure in the crystalline
state of III and VI is not significantly evidenced by their
melting temperature (74.5 and 73.1 ꢁC, respectively) nor
by their melting enthalpy values (43.3 and 38.1 kJ/mol,
respectively), as determined by DSC, thus inducing to
consider both III and VI as substantially equivalent
model compounds of the repeating units in the related
polymeric derivatives.
On the basis of these observations we can assume that
compounds III and VI are completely pentacoordinated
in the solid state and loose this ordered structure when
in the presence of a solvating agent. In order to assess
the influence of the solvent on the tin coordination num-
ber, III and VI were analyzed by both 13C and 119Sn
NMR in C6D6 solution, checking the d(119Sn) and the
1J(13C, 117Sn/119Sn) behaviour (Table 1), since both
these parameters are directly related to the central metal
atom arrangement [14]. In fact, in the case of a trigonal
bipyramidal arrangement, it should be reasonably ex-
pected a d (119Sn) value shifted towards higher field
Fig. 4. Supramolecular assembly of tri-n-butyltin carboxylate III
chains as determined by X-ray diffraction, viewed along the chain
propagation axis.
The X-ray structures of III and VI confirm the penta-
coordination of tin atoms, as suggested by IR spectra. In
III (Fig. 1) the tin–oxygen distances are in the range
˚
2.168(9) for the ester oxygen Sn1–O1, to 2.476(11) A
for the carbonyl oxygen atom Sn1–O2_2. Similarly, in
compound VI (Fig. 2) the range is from 2.165(5) for
4
[8]. The J(119Sn, 117Sn) might not be visible anyway,
˚
Sn1–O1 to 2.517(6) A for Sn1–O2_2.
due to the long-range coupling sensitivity to bond length
[16], since the coupling pathway passes through a rather
long bond distance Sn–O, as evidenced by X-ray struc-
tures. None of these changes was however observed
In the solid state both these compounds are arranged
in ordered, quasi-linear, infinite chains and purely steric
factors seem to drive their packing (Fig. 3). Steric hin-
Fig. 5. Supramolecular assembly of tri-n-butyltin carboxylate VI chains as determined by X-ray diffraction, viewed along the chain propagation axis.

L. Angiolini et al. / Journal of Organometallic Chemistry 689 (2004) 3301–3307
3305
upon passing from CDCl3 to C6D6, accounting for a tet-
4. Experimental
rahedral arrangement even in a weakly polar solvent for
both the compounds III and VI. Moreover the 13C
NMR spectra display 1J(13C, 117Sn/119Sn) values similar
to those observed in CDCl3 (Table 1), thus confirming a
pseudo-tetrahedral arrangement of the tin atom.
Chemicals are supplied by Sigma–Aldrich and gener-
ally used as received. Solvents are purified using normal
purification techniques [17].
Elemental analyses were performed by REDOX s.n.c.
(Milano).
1H and 13C NMR spectra are recorded both on a
Varian Gemini 300 NMR and Varian Mercury 400
NMR using CDCl3 and C6D6 solutions and tetrameth-
ylsilane as internal standard. 119Sn NMR spectra are re-
corded on Varian Mercury 400 using CDCl3 and C6D6
solutions and tetramethyltin as external standard. In
describing the NMR spectra we will use the following
notation: Ci = ipso carbon of the functionalized phenyl
group, bound to the variable substituent; Co = ortho;
Cm = meta; Cp = para.
3. Conclusions
4-(Ethyl)-phenyl-ethanoic acid tributyltin ester and 4-
(isopropyl)-phenyl-ethanoic acid tributyltin ester were
prepared from the corresponding carboxylic acids by di-
rect esterification with BTBTO and by reaction with
Bu3SnCl of the carboxylic acid sodium salt, respectively.
Both of them exhibit tetracoordinated and pentaco-
ordinated tin atom in solution and in the solid state,
respectively, as suggested by IR analysis.
A more detailed structure elucidation carried out by
X-ray diffraction techniques confirms the pentacoordi-
nation of tin in the solid state and shows a different spa-
tial arrangement for these stannylated derivatives. The
difference in supramolecular structure can be attributed
to the sterical hindrance of the isopropyl substituent as
compared to the ethyl one. Their similar thermal behav-
iour allows to consider both of these compounds as
substantially equivalent models of the related macromo-
lecular derivatives.
Infrared spectra in KBr pellets are recorded by a Per-
kin–Elmer 1750 FT-IR spectrometer.
Melting points and DHm values of stannylated
compounds have been determined by differential scan-
ning calorimetry using a TA Instruments DSC 2920
modulated calorimeter. M.p. values are given as the
temperature value at the maximum of the endother-
mic peak.
A summary of the crystallographic data and struc-
tural refinement for compounds III and VI is reported
in Table 2. Both data collections were performed on a
Table 2
Crystal data and structure refinement for III and VI
Compound
III
VI
Empirical formula
Formula weight (g/mol)
Temperature (K)
C
22H38O2Sn
C23H40O2Sn
467.24
293(2)
453.21
293(2)
0.71073
Monoclinic
P2(1)/c
˚
Wavelength (A)
˚
0.71073 A
Crystal system
Space group
Unit cell dimensions
Monoclinic
P2(1)/c
˚
a (A)
14.207(4)
17.681(6)
10.292(3)
109.445(8)
2437.9(13)
4
16.182(3)
10.551(2)
16.537(3)
114.998(4)
2559.0(9)
4
˚
b (A)
˚
c (A)
b (ꢁ)
3
˚
V (A )
Z
Dcalc (Mg/m3)
Absorption coefficient (mmÀ1
Crystal size (mm)
1.235
1.059
1.213
1.010
)
0.80 · 0.10 · 0.10
1.52–25.00
0.20 · 0.05 · 0.05
1.39–25.00
h Range for data collection (ꢁ)
Reflections collected/unique [Rint
Completeness to h = 25.00 (%)
Absorption correction
]
21163/4287 [0.5160]
100.0
Empirical
19589/4506 [0.0730]
100.0
Empirical
Maximum and minimum transmission
Refinement method
0.9015 and 0.4847
Full-matrix least-squares on F2
4287/112/226
0.9512 and 0.8235
Full-matrix least-squares on F2
4506/154/203
Data/restraints/parameters
Goodness-of-fit on F2
0.914
0.956
Final R indices [I > 2r(I)]
R indices (all data)
Largest difference peak and hole (e A
R1 = 0.1245, wR2 = 0.2015
R1 = 0.2709, wR2 = 0.2218
0.726 and À0.742
R1 = 0.0656, wR2 = 0.1721
R1 = 0.1156, wR2 = 0.1867
0.699 and À0.773
À3
˚
)

3306
L. Angiolini et al. / Journal of Organometallic Chemistry 689 (2004) 3301–3307
Bruker SMART 2000 equipped with a CCD detector.
An empirical absorption correction was applied (SA-
DABS) [18]. Crystals of compound III were not of a very
good quality and this gave high value of Rint. The struc-
tures were solved by direct methods and refined with
full-matrix least-square (SHELX-97) [19]. Non-hydrogen
atoms were refined anisotropically with the exception
of disordered groups, specifically both alkyl and aryl
groups in compund IV, which were split in two posi-
tions, using distance and anisotropic displacement
parameter restraints, and refined isotropically. Hydro-
gen positions were set geometrically.
4.3. 4-(Isopropyl)-phenyl-ethanoic acid (V)
In a nitrogen flushed three necked 100 ml round bot-
tomed flask, equipped with magnetic stirrer and drop-
ping funnel, 0.43 g (12.3 mmol) of clean magnesium is
added to 30 ml of freshly distilled THF, then a solution
of 2.07 g (12.3 mmol) of 4-isopropyl-benzylchloride in
10 ml of THF is slowly dropped in. The mixture is
heated at 35 ꢁC and allowed to react until no more mag-
nesium is present. Carbon dioxide is then bubbled in the
solution for 3 h. Saturated NH4Cl aqueous solution is
added, the organic phase washed twice with this solution
and finally with brine. The organic phase is treated with
10% NaOH solution and extracted with CHCl3, and
then the aqueous phase is made acidic by addition of
concentrated HCl and further extracted with CHCl3.
The organic solvent is distilled off and the product is
purified by crystallization with petroleum ether.
M.p. = 49 ꢁC (lit. 52 ꢁC [21]). Yield: 0.92 g (42%).
1H NMR: 7.2 (s, 4H, arom.); 3.6 (s, 2H, CH2); 2.9
(hept, 1H, CH); 1.2 (d, 6H, CH3).
4.1. 4-(Ethyl)-phenyl-ethanoic acid (II)
1.00 g (6.16 mmol) of 2-(4-styryl)-ethanoic acid and
50 mg of Pd 5% on carbon are dissolved in 50 ml of
THF. The solution is hydrogenated at 3 atm for 3 h at
room temperature in a Parr apparatus. The suspension
is filtered on silica and evaporated to give 1.01 g of (4-
ethyl)-phenyl-ethanoic acid corresponding to a quantita-
tive yield. M.p. = 91 ꢁC (lit. 91 ꢁC [20])
13C NMR: 178.7 (COOH); 148.7 (Cp); 131.2 (Ci);
129.9 (Co); 127.4 (Cm); 41.3 (CH2); 34.4 (CH); 24.6
(CH3).
1H NMR: 10.4 (bs, 1H, COOH); 7.2 (m, 4H, arom.);
3.6 (s, 2H, CH2CO); 2.6 (q, 2H, CH2–CH3); 1.2 (t, 3H,
CH3).
FT-IR: 3412 (mOH acid); 2959 (mCH aliph.); 1708 (mCO
acid); 815 (d1,4-subst.ring arom.) cmÀ1
.
13C NMR: 179.1 (COOH); 144.0 (Cp); 131.1 (Ci);
130.0 (Co); 128.8 (Cm); 41.4 (Ar-CH2); 29.1 (CH2CH3);
16.2 (CH3).
4.4. 4-(Isopropyl)-phenyl-ethanoic acid tributyltin ester
(VI)
FT-IR: 3445 (mOH acid); 2959–2868 (mCH aliph.); 1699
(mCO acid); 824 (d1,4-subst.ring arom.) cmÀ1
.
In a nitrogen flushed three necked 100 ml round bot-
tomed flask, equipped with magnetic stirrer and drop-
ping funnel, 0.03 g (3.5 mmol) of sodium is added to 7
ml of absolute ethanol. When the metal is completely re-
acted, 0.5 g of 4-(isopropyl)-phenyl-ethanoic acid (2.8
mmol) dissolved in 7 ml of absolute ethanol is dropped
during 30 min time, then 0.92 g (2.8 mmol) of Bu3SnCl is
slowly added. NaCl formation is observed and after fil-
tration, the solvent is distilled off. The 4-(isopropyl)-phe-
nyl-ethanoic acid tributyltin ester gives air stable white
prismatic crystals by crystallization with ethanol–water
(1:1). Yield: 0.78 g (65%). M.p. = 73.1 ꢁC. DHm = 38.1
kJ/mol.
4.2. 4-(Ethyl)-phenyl-ethanoic acid tributyltin ester (III)
In a 100 ml flask equipped with a Dean Stark appa-
ratus 0.70 g (4.26 mmol) of (4-ethyl)-phenyl-ethanoic
acid is dissolved in toluene (40 ml) and 2.2 ml (4.26
mmol) of bis(tributyltin) oxide is added. The reaction
mixture is heated until no more water evolution is ob-
served and toluene is further distilled under reduced
pressure. The (4-ethyl)-phenyl-ethanoic acid tributyltin
ester gives air stable white prismatic crystals by crystal-
lization with ethanol–water (1:1). Yield: 1.54 g (79%).
M.p. = 74.5 ꢁC. DHm = 43.3 kJ/mol.
Anal. Calc.: C, 58.30; H, 8.45; O, 7.06; Sn, 26.19.
Found: C, 58.49; H, 8.31; O, 6.99%.
Anal. Calc.: C, 59.12; H, 8.63; O, 6.85; Sn, 25.4.
Found: C, 59.31; H, 8.41; O, 6.98%.
1H NMR: 7.1–7.2 (2dd, 4H, arom.), 3.6 (s, 2H,
CH2CO), 2.6 (q, 2H, CH2–CH3), 1.6 (m, 6H, CH2bBu),
1.2–1.4 (m, 15H, CH2aBu + CH2cBu + CH3–CH2), 0.9
(t, 9H, CH3Bu).
13C NMR: 177.8 (COO); 143.0 (Cp); 133.7 (Ci); 129.8
(Co); 128.4 (Cm); 42.3 (CH2CO); 29.1 (CH2–CH3); 28.6
(CH2bBu); 27.7 (CH2cBu); 17.1 (CH2aBu); 16.2 (CH3–
CH2); 14.3 (CH3Bu).
1H NMR: 7.1–7.2 (2dd, 4H, arom.); 3.6 (s, 2H,
CH2CO); 2.9 (hept, 1H, CH); 1.6 (m, 6H, CH2bBu);
1.2–1.4 (m, 18H, CH2aBu + CH2cBu + CH3–CH); 0.9 (t,
9H, CH3Bu).
13C NMR: 177.9 (COO); 147.6 (Cp); 133.8 (Ci); 129.8
(Co); 127.1 (Cm); 42.3 (CH2CO); 34.4 (CH); 28.5
(CH2bBu); 27.7 (CH2cBu); 24.7 (CH3CH); 17.1 (CH2aBu);
14.3 (CH3Bu).
FT-IR: 2956–2854 (mCH aliph.); 1572 (mCOOSn); 814
FT-IR: 2956–2854 (mCH aliph.); 1572 (mCOOSn); 814
(d1,4-subst.ring arom.) cmÀ1
.
(d1,4-subst.ring arom.) cmÀ1
.

L. Angiolini et al. / Journal of Organometallic Chemistry 689 (2004) 3301–3307
3307
[5] J. Otera, Chem. Rev. 93 (1993) 1449.
[6] M. Gielen, Chim. Nouv. 76 (2001) 33.
5. Supplementary material
[7] J.K. Tsagatakis, N.A. Chaniotakis, K. Jurkschat, S. Damoun, P.
Geerlings, A. Bouhdid, M. Gielen, I. Verbruggen, M. Biesemans,
J.C. Martins, R. Willem, Helv. Chim. Acta 82 (1999) 531.
[8] L. Angiolini, M. Biesemans, D. Caretti, E. Salatelli, R. Willem,
Polymer 41 (2000) 3913.
Crystallographic data for the structural analysis have
been deposited with the Cambridge Crystallographic
Data Centre, CCDC No. 231340 and 231341 for com-
pounds III and VI, respectively. Copies of this informa-
tion may be obtained free of charge from: The Director
CCDC, 12 Union Road, Cambridge CB2 1EZ, UK (fax:
+44(1223)336-033 or e-mail: deposit@ccdc.cam.ac.uk or
www: http://www.ccdc.cam.ac.uk).
[9] M. Hoch, Appl. Geochem. 16 (2001) 719.
[10] L. Angiolini, D. Caretti, L. Mazzocchetti, E. Salatelli, M.
Biesemans, R. Willem, J. Polym. Sci. A (in press).
[11] P.J. Smith, A.P. Tupciauskas, Annu. Rev. NMR Spectrosc. 8
(1978) 291.
[12] A.G. Davies, P.J. SmithComprehensive Organometallic Chemis-
try, vol. 2, Pergamon Press, New York, 1982, p. 564.
[13] D.A. Alleston, A.G. Davies, J. Chem. Soc. 12 (1962) 2050.
Acknowledgement
´
[14] J. Holeeek, M. Nadvornik, K. Hanlır, J. Organomet. Chem. 315
`
ˇ
(1986) 299.
The authors gratefully acknowledge the financial sup-
port by the University of Bologna (Progetti Pluriennali
di Ricerca 2001).
`
´ˇ
`
[15] J. Holeeek, K. Hanlır, A. Lyeka, T.K. Chattopadhyay, B.
Majee, A.K. Kumar, Collect. Czech. Chem. Commun. 51 (1986)
1100.
[16] M. Gielen, R. Willem, B. Wrackmeyer, Advanced Applications of
NMR to Organometallic Chemistry, Wiley, Chichester, 1996.
[17] D.D. Perrin, W.L.F. Armarego, D.R. Perrin, in: Purification of
Laboratory Chemicals, Pergamon Press, Oxford, 1966.
[18] G.M. Sheldrick, SADABS, University of Go¨ttingen, Germany.
[19] G.M. Sheldrick, SHELX-97. Programs for Crystal Structure
Solution and Refinement, University of Go¨ttingen, Germany,
1997.
References
[1] A.G. Davies, Organotin Chemistry, VCH, Weinheim, 1997.
[2] D. Seyferth, T.C. Masterman, Appl. Organomet. Chem. 8 (1994)
335.
[3] A.A. Mahmoud, A.F. Shaaban, M.M. Azab, N.N. Messia, Eur.
Polym. J. 28 (1992) 555.
[20] Y. Kusuyama, Y. Ikeda, Bull. Chem. Soc. Jpn. 46 (1973)
204.
[4] J.R. Dharia, C.P. Pathak, G.N. Babu, S.K. Gupta, J. Polym. Sci.
26 (1988) 595.
[21] E. Rothstein, F. Vallely, J. Chem. Soc., Perkin Trans. 1 (1974)
443.