Silica-anchored organotin trichloride: A recyclable and clean organotin catalyst for transesterification reactions

Article abstract of DOI:10.1039/c3dt50292a

A new synthetic scheme towards silica-supported organotrichlorotin derivatives has been developed. It involves the synthesis of (11-triethoxysilyl)undecyltricyclohexyltin, followed by sol-gel processing and, subsequently in the formation of the resulting hybrid silica, by electrophilic substitution of the tricyclohexyltin function by the target grafted trichlorotin using tin tetrachloride. HR-MAS ¹¹⁹Sn and CP-MAS ²⁹Si NMR combined with N₂-sorption and TEM measurements evidenced the formation of a mesoporous organic-inorganic hybrid silica including a functionally pure supported-organotrichlorotin species. This silica-grafted organotrichlorotin displays a satisfactory catalytic activity in the transesterification of ethyl acetate by 1-octanol. The catalyst could be recycled four times without significant loss of activity. Furthermore, tin leaching below 10 ppm evidences the benefits of the proposed strategy to limit tin contamination of the final products. The Royal Society of Chemistry 2013.

Full text of DOI:10.1039/c3dt50292a

Dalton
Transactions
View Article Online
View Journal | View Issue
PAPER
Silica-anchored organotin trichloride: a recyclable and
clean organotin catalyst for transesterification
reactions†
Cite this: Dalton Trans., 2013, 42, 9764
Thierry Toupance,*a Laetitia Renard,a Bernard Jousseaume,a Céline Olivier,a
Vanja Pinoie,b Ingrid Verbruggenb and Rudolph Willemb
A new synthetic scheme towards silica-supported organotrichlorotin derivatives has been developed. It
involves the synthesis of (11-triethoxysilyl)undecyltricyclohexyltin, followed by sol–gel processing and,
subsequently in the formation of the resulting hybrid silica, by electrophilic substitution of the tricyclo-
hexyltin function by the target grafted trichlorotin using tin tetrachloride. HR-MAS 119Sn and CP-MAS
29Si NMR combined with N2-sorption and TEM measurements evidenced the formation of a mesoporous
organic–inorganic hybrid silica including a functionally pure supported-organotrichlorotin species. This
silica-grafted organotrichlorotin displays a satisfactory catalytic activity in the transesterification of ethyl
acetate by 1-octanol. The catalyst could be recycled four times without significant loss of activity. Further-
more, tin leaching below 10 ppm evidences the benefits of the proposed strategy to limit tin contami-
nation of the final products.
Received 29th January 2013,
Accepted 22nd April 2013
DOI: 10.1039/c3dt50292a
www.rsc.org/dalton
promising materials for the reproducible and sensitive detec-
tion of combustible or toxic gases.5
Introduction
Thanks to the ability of the tin atom to form stable and rela-
However, the harmful environmental effects of some organo-
tively strong bonds with most elements, organotin compounds tin compounds have led to developments in these fields
show a very rich chemistry, which has attracted, over the past tending to decrease tin residues in commercial products. In
few decades, worldwide academic and practical focus.1 In this context, new synthetic methodologies involving organotin
industry, they are applied as poly(vinylchloride) stabilizers, reagents in order to create carbon–carbon bonds,6 fluorous
room temperature vulcanizing (RTV) silicone curing agents biphasic reactions7 and polymer-supported tin reagents8 or
and homogeneous catalysts for transesterification reactions catalysts,9 leading to the target compounds with low tin resi-
and polyurethane polymerization.2 Furthermore, the versatile dues, have been successfully developed. As far as “green” organo-
reactivity of organotins, either homolytic or heterolytic tin catalysts for transesterification reactions are concerned,
depending upon the experimental conditions employed, gave polymer-grafted organotin species9 have been mainly develo-
rise to many applications in organic synthesis, exploiting for ped so far and excellent catalytic properties have been reported
instance, tetraorganotins to generate organolithium reagents for polystyrene-grafted dichlorobutyltins,9a,b distannoxanes9d,f
or the reductive properties of triorganotin hydrides.3 In and trichlorotins.9c,e,g,h In particular, the C11-grafted organo-
materials chemistry, combining the design of functional tin trichloride, in which an undecyl chain connects the tin
hydrolyzable organotins and sol–gel chemistry has allowed for center to the cross-linked polymer backbone, appeared to be
new prospects in the field of organic–inorganic hybrid most promising both in terms of catalytic efficiency and cata-
materials.4 Thus, functional tin oxide based nanostructures lyst recyclability.9e–h When compared to organic polymer car-
designed from organotin trialkynides appeared to be riers, silica-based supports are expected to yield better thermal
and chemical stabilities and no swelling or shrinking when
immersed in a solvent. However, despite these potential
aUniversity of Bordeaux, Institut des Sciences Moléculaires, ISM UMR 5255 CNRS,
C2M group, 33405 Talence Cédex, France. E-mail: t.toupance@ism.u-bordeaux1.fr;
Fax: +33 5 40006994; Tel: +33 5 40002523
bHigh Resolution NMR Centre (HNMR), Department of Materials and Chemistry
(MACH), Vrije Universiteit Brussel (UVB), Pleinlaan 2, B-1050 Brussels, Belgium
†Electronic supplementary information (ESI) available: CP-MAS 117Sn NMR
spectra and TG mass loss data. See DOI: 10.1039/c3dt50292a
advantages, only a few silica-supported organotins have been
reported so far,10 their most interesting use concerning Prins
condensation11 and Baeyer–Villiger12 reactions. Moreover, to
the best of our knowledge, the use of silica-supported organo-
tins to catalyze transesterification reactions has not been
reported so far.
9764 | Dalton Trans., 2013, 42, 9764–9770
This journal is © The Royal Society of Chemistry 2013

View Article Online
Dalton Transactions
Paper
As a consequence, we herein report a silica-supported tri- (resp. 10.6 ppm) in the 1H NMR (resp. {1H}–13C NMR) spec-
chloroorganotin catalyst for transesterification reactions in trum of 2 is typical for a CH2–Si group indicating that the
which the tin functionality is connected to the silica support silicon addition actually occurred at the terminal Csp2 carbon
by an undecyl chain in order to ensure good mobility and of alkene 1 (Fig. S1†). Subsequently, compound 2 was alterna-
accessibility to the catalytic site. This novel catalyst was syn- tively first co-hydrolyzed with tetraethoxysilane (TEOS) in the
thesized using an organic–inorganic hybrid approach invol- presence of an acidic (i.e. HCl), a basic (i.e. NaOH) or a nucleo-
ving the co-hydrolysis of a mixed organotin–organosilicon philic (i.e. NH4F) catalyst to yield a hybrid silica that includes
trialkoxide with tetraethoxysilane, followed by reaction of the an undecyltricyclohexyltin group. Whatever the catalyst used,
resulting organic–inorganic hybrid materials with tin tetra- the FTIR spectrum of 3 showed the resonances characteristic
chloride. The catalytic and recyclability properties in trans- for sol–gel silica, i.e. 3650 (shoulder, νOH silanol), 3414 (broad,
esterification reactions involving primary alcohols are presented νOH bonded), 1638 (δOH bonded), 1089 (νaSsi–O–Si), 961 (νSi–OH),
and discussed.
and 801 (νsSi–O–Si) cm−1. Moreover, the strong bands at 2920
(νaCsH2) and 2849 (νsCH2) cm−1 along with the weaker one at 1446
(δCH2) cm−1 are characteristic for the undecyltricyclohexyltin
moiety. The chemical environments of the tin and silicon
atoms in the hybrid materials were further probed by solid-
state 117Sn and 29Si MAS NMR, using standard procedures.9f,14
Regardless of the sol–gel conditions used to obtain 3, the
117Sn MAS spectrum exhibited an isotropic 117Sn chemical
shift at −65 ppm characteristic of tricyclohexylalkyltin deriva-
tives (Fig. S2A†).13,15
Results and discussion
As we have previously shown that alkyltin trichlorides can be
easily prepared from tricyclohexyltin chloride,13 a synthetic
route starting from the latter was developed to prepare the
target silica-supported organotin trichloride catalyst as shown
in Scheme 1. In a first step, the Grignard reagent of 1-bromo-
10-undecene reacted with tricyclohexyltin chloride to give tri-
cyclohexylorganotin 1 with 79% yield. Introduction of the
Si(OEt)3 group was then achieved through hydrosilylation of
the unsaturated precursor 1 with an excess of HSi(OEt)3
(2 equiv.) in the presence of a platinum catalyst (Karstedt
catalyst), which yielded almost quantitatively the organotin-
substituted organosilicon alkoxide 2. Compound 2 displays
resonances at −44.6 ppm in the {1H}–29Si NMR spectrum and
at −64.5 ppm in the {1H}–119Sn NMR spectrum characteristic
of alkylsilicon trialkoxide and alkyltricyclohexyltin moieties,
respectively. Moreover, a low frequency resonance at 0.6 ppm
The HR-MAS 119Sn NMR16 spectrum of 3, recorded in the
presence of CDCl3,9e–h enables one to obtain NMR spectral
information concerning the grafted organotin moiety dipped
in solution, in situ directly at the solid–solution interface.
A single resonance at −66 ppm was observed, indicating that
the tin atom is tetracoordinated in the dry solid state as well as
in the presence of a solvent (Fig. 1A). The fact that the
C11–SnCy3 functionality is indeed grafted in material 3 is
unambiguously supported by the characteristic signals found
in diffusion filtered 1H HR-MAS NMR spectra,16 enabling
specific spectral editing of grafted moieties, at the expense of
resonances from free, translationally mobile species that are
completely suppressed. Besides, the 29Si MAS NMR spectrum
of the hybrid silica is characteristic of a condensed silica
Fig. 1 Solid state 117Sn HR-MAS NMR spectra of 3 (A) and 4 (C) and 29Si MAS
NMR spectra of 3 (B) and 4 (D).
Scheme 1 Synthetic pathway to the target catalyst.
This journal is © The Royal Society of Chemistry 2013
Dalton Trans., 2013, 42, 9764–9770 | 9765

View Article Online
Paper
Dalton Transactions
Table 1 Chemical formula and textural properties of the different hybrid materials prepared
Material
Sol–gel hydrolysis conditions
Proposed chemical formula
C23.9H47.5O11Si4.7Sn0.7
SBET (m2 g−1
)
Average pore size (nm)
3
NH4F
HCl
NaOH
NH4F/SnCl4
43
2
30
2
1
a
3a
3b
4
C25H48O12Si4.8Sn0.8
<2
—
—
a
C19H37O11.3Si4.6Sn0.6
C10.5H22.4Cl2.1O11Si4.7Sn0.7
<2
153
5
14
a Non porous.
network (Fig. 1B).17 The spectrum of the hybrid silica presents
a main peak at −108 ppm with a shoulder around −100 ppm
along with less intense resonances at −56 ppm and −65 ppm
assigned to T2 and T3 species. On the basis of all these data, it
can be concluded that the tricyclohexyltin group is inserted into
the hybrid silica with a tin loading of about 1.0 0.2 mmol g−1
according to TGA and microanalysis data (Table 1). By contrast,
the hydrolysis conditions have a drastic influence on the tex-
tural properties of the hybrid powder obtained. Thus, nucleo-
philic catalysis with ammonium fluoride yielded the hybrid
material 3 showing the highest specific surface area, i.e. 43
2 m2 g−1, in strong contrast with the materials prepared under
Fig. 2 (A) N2 sorption isotherm and pore size distribution (insert) for material
3 (square, black) and hybrid catalyst 4 (triangle, red); (B) TEM image of the
hybrid catalyst 4.
basic or acidic conditions, i.e. less than 2 m2 g−1
.
As the highest surface area is expected to provide the
highest catalytic efficiency, hybrid material 3 was therefore
reacted with tin tetrachloride in order to obtain the trichloro-
tin analogue 4, after elimination of tricyclohexyltin chloride.
As expected, the significant decrease of the methylene stretch-
ing vibration modes at 2920 (νCasH2) and 2849 (νsCH2) cm−1 was
detected by FTIR spectroscopy. On the other hand, no v(Sn–O)
vibration band was observed in the FTIR spectrum of hybrid
material 4 in the 400–700 cm−1 region ruling out any signifi-
cant reaction of tin tetrachloride with silica surface hydroxyl
groups (Fig. S3†). In addition, the 117Sn MAS NMR spectrum of
4 showed a single isotropic chemical shift located around
0 ppm (Fig. S2B†), with a very broad and noisy resonance,
expanding over several tenths of ppm, characteristic for tri-
converted quantitatively into trichlorotin functionalities
without affecting the silica network. Moreover, the hybrid
material 4 showed improved textural properties with a strong
enhancement of the BET surface area, i.e. 153 5 m2 g−1. This
behaviour might be related to the elimination of the highly
hydrophobic and bulky tricyclohexyl group, a similar trend
having been reported for the silsesquioxane network including
hydrophobic linkers after chemical post-treatment.18 The N2
adsorption isotherms of 4 exhibit a type IV-like behaviour
including a type H2 hysteresis loop (Fig. 2A) characteristic for
mesoporous materials according to the IUPAC classification.19
The pore size distribution based on the adsorption branch is
quite narrow with an average pore diameter of 14 nm. The
TEM images of 4 confirmed that this material has a good
porous structure, comparable to “worm-hole”- or “sponge”-like
porous materials,20 with many small pores (Fig. 2B). All these
data are therefore consistent with the formation of undecyltri-
chlorotin functions grafted onto a hybrid silica support.
chloroalkyltin moieties. The HR-MAS 119Sn NMR spectrum of
9e–h
4, likewise in the presence of CDCl3
as for 3, provides a
single, broader resonance around 0 ppm, indicating again that
the tin atom tetracoordination in 4 is identical in the dry solid
state and in the presence of a solvent (Fig. 1C), as observed for
3. The visible upfield shoulder in the resonance has been
shown earlier to arise from the weak interaction with a water
molecule, the presence of which was demonstrated before to
be unavoidable, but also harmless for chemical and catalytic
Acetylation of 1-octanol by ethyl acetate was investigated in
the presence of 3, 4 or a soluble analogue (Scheme 2). Reac-
tions were carried out with a sevenfold excess of ethyl acetate
1
stability.9e,g Again, H diffusion filtered HR-MAS NMR spectra
of 4 unambiguously evidence the C11–SnCl3 target functional-
ity to be still grafted onto the silica support after conversion
from 3 to 4. Similarly, the expected bands of a condensed
mixed hybrid silica/silica network were also observed for 4 by
29Si MAS solid state NMR (Fig. 1D). Thus, the spectrum of 4
again exhibits a main peak at −109 ppm with a shoulder
around −102 ppm along with smaller contributions at
−58 ppm and −65 ppm assigned to T2 and T3 species. As a
consequence, all the tricyclohexyltin functions have been
Scheme 2 Transesterification of 1-octanol by ethyl acetate to ethanol and
1-octylacetate catalyzed by hybrid material 4.
9766 | Dalton Trans., 2013, 42, 9764–9770
This journal is © The Royal Society of Chemistry 2013

View Article Online
Dalton Transactions
Paper
under reflux for up to 48 h for each catalyst studied. Conver- dephenylation of the intermediate grafted undecyl triphenyltin
sion degrees were determined by 1H NMR, after filtration of obtained, failed to provide functionally pure undecyltrichloro-
the solid-supported catalyst and removal of the excess of ethyl tin.21 Thus, in contrast with earlier observations on cross-
acetate. For the sake of comparison, the activity of 4 was com- linked polystyrene grafted undecyltrichlorotin, which was
pared with that of 3 and of a homogeneous catalyst analogue obtained functionally pure,9f–h the same reaction pathway pro-
in solution, BuSnCl3 or BuSnO(OH)Cl, all with identical molar vided at best a silica grafted mixture of undecyltintrichloride
fractions, i.e. 1 mol%. The results are reported in Fig. 3. While and undecylphenyltindichloride in the molar ratio 4 : 1. Not-
3 led to no conversion after several hours, the catalyst 4 led to withstanding this limitation, the latter material displayed com-
satisfactory activity with a conversion yield higher than 95% parable catalytic activity.21
after 20 hours comparable to that reached after 2–4 hours with
the homogeneous analogue. Moreover, the catalyst 4 could be
recycled four times without any significant decrease of its
catalytic activity showing that it remains stable under the
Conclusions
experimental conditions used. Besides, tin leaching, expressed We have successfully developed a new synthetic route leading
in tin mass, is rather low, i.e. 10 ppm per run (Fig. 3C), and to silica-supported organotrichlorotins for application as
comparable with that reported for tin-grafted polystyrene catalysts in transesterification reactions. The key step involved
supports.9e–h
the electrophilic cleavage by tin tetrachloride of a tricyclo-
An alternative reaction pathway to the hybrid catalyst 4, con- hexyltin function introduced into a hybrid silica network
sisting of reacting the undecyl bromide grafted to silica with yielding functionally pure supported-organotrichlorotin species.
triphenylstannyl lithium, followed by triple hydrochloro- Compared to the preparation route of the polymer-grafted ana-
logues, the above-described method is straightforward avoid-
ing the use of long time-consuming and solvent-wasting
washing steps.9 The resulting porous hybrid catalyst showed a
satisfactory activity in the transesterification reaction studied.
The satisfactory tin leaching amounts along with the good
recyclability of the organotrichlorotin-grafted silica compared
to its soluble analogue clearly evidenced the benefits of our
proposed strategy in the field of organotin chemistry and
catalysis.
Experimental section
Materials and methods
All manipulations of air- and/or moisture-sensitive compounds
were carried out using standard Schlenk lines under a nitrogen
atmosphere or under vacuum. Pentane, toluene, THF and
diethyl ether were dried and distilled from sodium benzophe-
none ketyl prior to use. Acetonitrile was dried over CaH2 and
then distilled. Tin tetrachloride (Acros Organics) and triethoxy-
silane (Aldrich) were distilled just before use. The Karstedt
catalyst (platinum(0)-1,3-divinyl-1,1,3,3-tetramethyldisiloxane
complex solution in xylene, Aldrich) was used as received. Tri-
cyclohexyltin chloride was synthesized according to a literature
method.22 Solution 1H, 13C and 119Sn NMR spectra were
recorded on a Bruker DPX-300 spectrometer (solvent CDCl3).
Chemical shifts are quoted in δ (ppm) and coupling constants
in hertz, while “t” stands for triplet, “q” for quartet and “m”
for multiplet. Tin-carbon coupling constants (Hz) are given in
brackets. The solid state 29Si and 117Sn spectra were recorded
on a Bruker DRX 250 MHz instrument, using procedures
described earlier.9g,14 The HR-MAS 119Sn NMR spectra were
recorded in CDCl3 on a Bruker Avance2 500 MHz instrument,
using procedures described elsewhere.9e–h,16 Infrared spectra
Fig. 3 Catalytic activities: (A) conversion degree as a function of time for
(KBr pellets or disks) were recorded in the absorption mode
using an FTIR Perkin-Elmer spectrophotometer. Elemental
BuSnCl3 or BuSnO(OH)Cl (blue), hybrid material 3 (green) and hybrid catalyst 4
(red); (B) recycling tests; (C) tin leaching.
This journal is © The Royal Society of Chemistry 2013
Dalton Trans., 2013, 42, 9764–9770 | 9767

View Article Online
Paper
Dalton Transactions
analyses were carried out in the Centre of Chemical Analysis of
the CNRS (Vernaison France).
Hybrid material 4. In a Schlenk tube under a nitrogen
atmosphere, tin tetrachloride was added dropwise (0.25 mL,
2.1 mmol) to a suspension of 3 (0.77 g) in toluene (5 mL) and
the reaction medium was then heated at 55 °C for 24 hours.
After filtration, the obtained powder was washed several times
with toluene and then dried in vacuo at 60 °C for 5 hours to
give a yellowish powder. Yield: 1.94 g. Anal. found (Calcd for
Synthesis
C10.5H22.4Cl2.1O11Si4.7Sn0.7): C 20.5 (20.5), H 3.9 (3.7), Sn 13.8
Undec-10-enyltricyclohexyltin 1. In
a three-necked flask (13.5), Cl 13.0 (12.2).
under a nitrogen atmosphere, a solution of 11-bromoundec-1-
ene (6.87 g, 28 mmol) in diethyl ether (23 mL) was added drop-
wise to a suspension of magnesium (0.89 g, 36 mmol) in
diethyl ether (5 mL) under vigorous stirring. The resulting
mixture was refluxed for 1 h. After cooling, this mixture was
slowly added to a solution of tricyclohexyltin trichloride
(7.98 g, 21.5 mmol) in diethyl ether (80 mL). The mixture was
then refluxed for another 2 h. After hydrolysis with a saturated
solution of NH4Cl, the resulting organic phases were washed
three times with water (80 mL) and dried over MgSO4 to yield a
yellowish oil after evaporation of the solvent. Further purifi-
cation by column chromatography over silica (eluent: pet-
roleum ether) gave a colorless oil. Yield: 10.45 g (93%). 1H
NMR (300 MHz, CDCl3, 293 K): δ 0.78 (m, 2H, H1), 1.29–2.08
(m, 49H, Ha–d and H2–9), 4.97 (m, 2H, H11), 5.82 (m, 1H, H10).
13C NMR (74.5 MHz, CDCl3, 293 K): δ 7.0 ([268], C1), 26.2
([320], Ca), 27.6 (Cd), 29.3, 29.5, 29.7 (Cc), 29.9, 30.0, 32.7 ([15],
Cb), 34.2 (C9), 35.4 ([50], C3), 114.4 (C11), 139.2 (C10). 119Sn
NMR (111.9 MHz, CDCl3, 293 K): δ −64.5. Anal. found (Calcd
for C29H54Sn): C 67.1 (66.8), H 10.6 (10.4), Sn 22.5 (22.7).
Triethoxysilylundecyltricyclohexyltin 2. In a Schlenk tube
under a nitrogen atmosphere, a few drops of the Karstedt cata-
lyst were slowly added to a solution of 1 (3.01 g, 5.8 mmol) and
triethoxysilane (2.1 mL, 11.2 mmol) in toluene (10 mL). The
resulting mixture was then stirred overnight at room temp-
erature. Evaporation of the toluene and drying in vacuo at 50 °C
for 6 h gave a colorless oil. Yield: 3.75 g (94%). 1H NMR
(300 MHz, CDCl3, 293 K): δ 0.63 (m, 2H, H11), 0.76 (m, 2H, H1),
1.22 (t, 9H, H13), 1.22–1.85 (m, 51H, Ha–d and H2–10), 3.81 (q,
6H, H12). 13C NMR (74.5 MHz, CDCl3, 293 K): δ 7.0 ([262], C1),
10.5 (C11), 18.4 (C13), 23.0 (C9) 26.1 ([320], Ca), 27.4 (Cd), 29.1,
29.4, 29.5 (Cc), 29.8, 30.0, 32.5 ([15], Cb), 32.6, 32.7, 33.4 (C9),
35.3 ([49], C3), 58.4 (C12). 29Si NMR (59 MHz, CDCl3, 293 K): δ
−44.6. 119Sn NMR (111.9 MHz, CDCl3, 293 K): δ −64.5. Anal.
found (Calcd for C35H70O3SiSn): C 61.4 (61.3), H 10.6 (10.3), Si
4.5 (4.1), Sn 16.7 (17.3).
Catalysis experiments
A mixture of ethyl acetate (6.5 mL, 665 mmol), 1-octanol
(1.5 mL, 95 mmol) and hybrid catalyst 4 (0.1 g, 0.11 mmol)
was refluxed for 48 hours. The transesterification reaction was
monitored by removing 100 μL aliquots at regular intervals
and analyzing each aliquot after evaporation of ethyl acetate
1
and ethanol, using solution H NMR spectroscopy with CDCl3
as a solvent. The ratio of initial 1-octanol to formed 1-octyl
acetate was estimated by integration of the respective (CH2O)
1H NMR resonances. After each catalytic run, the reaction
mixture was centrifuged and, after elimination of the super-
natant, the resulting powder was washed three times with
dichloromethane and, then, dried in vacuo.
Sample characterization
TGA studies were carried out on a Netzsch STA simultaneous
analyzer. Thermogravimetry (TG) traces were recorded in the
50–600 °C temperature range with a heating rate of 10 °C
min−1 under an air flow. Infrared spectra (KBr pellets) were
recorded in the transmission mode using an FTIR Perkin-
Elmer spectrophotometer. The texture of the dried and cal-
cined samples was analysed by nitrogen adsorption isotherm
(77 K) measurements. Data collection was performed by the
static volumetric method, using an ASAP2010 (Micromeritics)
apparatus. Prior to each measurement, the samples were
degassed at 120 °C in vacuo for a time long enough to reach a
constant pressure (<10 μmHg). The BET equation was applied
between 0.05 and 0.3 relative pressures to provide specific
surface areas. Total pore volumes were determined by the
amount of nitrogen adsorbed at a 0.99 relative pressure. Pore
size distributions were evaluated by the Barrett, Joyner,
Halenda (BJH) method for mesopores (pores of diameter
2–50 nm).23 The adsorption isotherm was used to determine
the overall pore size distribution and the calculation was per-
formed by the Micromeritics software package which uses the
recurrent method and applies the Harkins and Jura equation
for the multilayer thickness.
Hybrid material 3. In a Schlenk tube under a nitrogen
atmosphere and under vigorous stirring, an aqueous solution
of ammonium fluoride was added dropwise (0.91 mL,
0.27 mmol) to a solution of 2 (3.75 g, 5.5 mmol) and tetra-
ethoxysilane (4.55 g, 21.9 mmol) in 2-propanol (14.7 mL). Geli-
fication took place within 1 hour and the gel was then aged
Acknowledgements
nine days at room temperature without stirring. After filtration, Mrs Odile Babot and Mrs Elisabeth Sellier are acknowledged
the obtained gel was washed several times with THF and for N2 sorption and TEM measurements, respectively. R. W.,
ethanol and then lyophilized to give a white powder. Yield: V. P. and I. V. are indebted to the research council of the VUB
2.95 g (68%). Anal. found (Calcd for C23.9H47.5O11Si4.7Sn0.7): C for financial support (“Geconcerteerde Onderzoeksactie”,
39.9 (39.5), H 6.8 (6.6), Sn 10.9 (11.4).
GOA31).
9768 | Dalton Trans., 2013, 42, 9764–9770
This journal is © The Royal Society of Chemistry 2013

View Article Online
Dalton Transactions
Paper
Chem.–Eur. J., 2005, 11, 2455–2461; corrigenda:
C. Camacho-Camacho, M. Biesemans, M. Van Poeck,
F. A. G. Mercier, R. Willem, K. Darriet-Jambert,
B. Jousseaume, T. Toupance, U. Schneider and
U. Gerigk, Chem.–Eur. J., 2005, 11, 3500; (d) G. Deshayes,
K. Poelmans, I. Verbruggen, C. Camacho-Camacho,
P. Degée, V. Pinoie, J. C. Martins, M. Piotto,
M. Biesemans, R. Willem and P. Dubois, Chem.–Eur. J.,
2005, 11, 4552–4561; (e) V. Pinoie, K. Poelmans,
H. E. Miltner, I. Verbruggen, M. Biesemans, G. Van
Assche, B. Van Mele, J. C. Martins and R. Willem, Orga-
nometallics, 2007, 26, 6718–6725; (f) K. Poelmans,
V. Pinoie, I. Verbruggen, M. Biesemans, G. Van Assche,
G. Deshayes, P. Degée, P. Dubois and R. Willem, Appl.
Organomet. Chem., 2007, 21, 504–513; (g) K. Poelmans,
V. Pinoie, I. Verbruggen, M. Biesemans, G. Deshayes,
E. Duquesne, C. Delcourt, P. Degée, H. E. Miltner,
P. Dubois and R. Willem, Organometallics, 2008, 27,
1841–1849; (h) V. Pinoie, M. Biesemans and R. Willem,
Organometallics, 2010, 29, 193–198.
Notes and references
1 For a review see: A. G. Davies, in Organotin Chemistry, VCH,
Weinheim, Germany, 2004.
2 (a) A. G. Davies and P. J. Smith, in Comprehensive Organo-
metallic Chemistry, ed. F. G. A. Stone and E. W. Abel, Perga-
mon, New York, U.S., 1982, vol. 2, p. 610; (b) C. J. Evans, in
Chemistry of Tin, ed. P. J. Smith, Blakie, New York, U.S.,
2nd edn, 1998, p. 444; (c) J. Otera, Chem. Rev., 1993, 93,
1449–1470.
3 For a review see: Tin Chemistry: Fundamentals, Frontiers
and Applications, ed. A. G. Davies, M. Gielen,
K. H. Pannell and E. R. T. Tiekink, Wiley, Chichester,
U.K., 2008.
4 (a) H. El Hamzaoui, B. Jousseaume, H. Riague,
T. Toupance, P. Dieudonné, C. Zakri, M. Maugey and
H. Allouchi, J. Am. Chem. Soc., 2004, 126, 8130–8131;
(b) H. Elhamzaoui, T. Toupance, M. Maugey, C. Zakri and
B. Jousseaume, Langmuir, 2007, 23, 785–789.
5 (a) L. Renard, H. Elhamzaoui, B. Jousseaume, T. Toupance,
G. Laurent, F. Ribot, H. Saadaoui, J. Brötz, H. Fuess, 10 (a) N. Y. M. Fung, J. H. de Mayo, J. H. Schauble and
R. Riedel and A. Gurlo, Chem. Commun., 2011, 47, 1464–
1466; (b) L. Renard, O. Babot, H. Saadaoui, J. Brötz,
H. Fuess, A. Gurlo, E. Arveux, A. Klein and T. Toupance,
Nanoscale, 2012, 6, 6806–6813.
6 (a) A. Hervé, A. Rodriguez and E. Fouquet, J. Org. Chem.,
2005, 70, 1953–1956; (b) M. Huiban, A. Huet, L. Barré,
F. Sobrio, E. Fouquet and C. Perrio, Chem. Commun., 2006,
97–99.
A. C. Weedon, J. Org. Chem., 1978, 43, 3977–3979;
(b) H. Schumann and B. Pachaly, Angew. Chem., Int. Ed.
Engl., 1981, 20, 1043–1044; (c) Q. J. Fu, A. M. Steele and
S. C. Tsang, Green Chem., 2001, 3, 71–73; (d) S. A. Matlin
and P. S. Gandham, J. Chem. Soc., Chem. Commun., 1984,
798–799; (e) S. Boutet, B. Jousseaume, M. Biesemans,
R. Willem, C. Labrugère and L. Delattre, Chem. Mater.,
2005, 17, 1803–1811.
7 (a) J. Xiang, S. Toyoshima, A. Orita and J. Otera, Angew. 11 (a) T. M. Jyothi, M. L. Kaliya and M. V. Landau, Angew.
Chem., Int. Ed., 2001, 40, 3670–3685; (b) J. Otera, Acc. Chem.
Res., 2004, 37, 288–296.
8 (a) U. Gerigk, M. Gerlach, W. P. Neumann, R. Vieler and
Chem., Int. Ed., 2001, 40, 2881–2884; (b) T. M. Jyothi,
M. L. Kaliya, M. Herskowitz and M. V. Landau, Chem.
Commun., 2001, 992–993.
V. Weintritt, Synthesis, 1990, 448–452; (b) H. Kuhn and 12 A. Yoshida, X. Hao, O. Yamazaki and J. Nishikido, Mole-
W. P. Neumann, Synlett, 1994, 123–124; (c) G. Dumartin, cules, 2006, 11, 627–640.
M. Pourcel, B. Delmond, O. Donard and M. Pereyre, Tetra- 13 B. Jousseaume, H. Riague, T. Toupance, M. Lahcini,
hedron Lett., 1998, 39, 4663–4666; (d) J. Cossy, D. Rasamiso
and D. Gomez Pardo, J. Org. Chem., 2001, 66, 7195–7198;
P. Mountford and B. R. Tyrrell, Organometallics, 2002, 21,
4590–4594.
(e) J.-M. Chrétien, F. Zammattio, D. Gauthier, E. Le 14 (a) G. Mosselmans, M. Biesemans, R. Willem, J. Wastiels,
Grognec, M. Paris and J.-P. Quintard, Chem.–Eur. J., 2006,
12, 6816–6828; (f) J.-M. Chrétien, A. Mallinger,
F. Zammattio, E. Le Grognec, M. Paris, G. Montavon and
J.-P. Quintard, Tetrahedron Lett., 2007, 48, 1781–1785;
(g) G. Kerric, F. Zammattio, E. Le Grognec, M. Paris and
J.-P. Quintard, J. Organomet. Chem., 2010, 695, 103–110;
(h) G. Kerric, E. Le Grognec, V. Fargeas, F. Zammattio,
M. Leermakers, H. Rahier, S. Brughmans and B. Van Mele,
J. Therm. Anal. Calorim., 2007, 88, 723–729; (b) H. Rahier,
J. Wastiels, M. Biesemans, R. Willem, G. Van Assche and
B. Van Mele, J. Mater. Sci., 2007, 42, 2982–2996;
(c) G. Dumartin, J. Kharboutli, B. Delmond, M. Pereyre,
M. Biesemans, M. Gielen and R. Willem, Organometallics,
1996, 15, 19–23.
J.-P. Quintard, M. Biesemans and R. Willem, J. Organomet. 15 G. Vilaça, K. Barathieu, B. Jousseaume and T. Toupance,
Chem., 2010, 695, 1414–1424. Organometallics, 2003, 22, 4584–4592.
9 (a) F. A. G. Mercier, M. Biesemans, R. Altmann, R. Willem, 16 J. C. Martins, F. A. G. Mercier, A. Vandervelden,
R. Pintelon, J. Schoukens, B. Delmond and G. Dumartin,
M. Biesemans, J.-M. Wieruszeski, E. Humpfer, R. Willem
Organometallics, 2001, 20, 958–962; (b) M. Biesemans,
and G. Lippens, Chem.–Eur. J., 2002, 8, 3431–3441.
F. A. G. Mercier, M. van Poeck, J. C. Martins, G. Dumartin 17 (a) G. Engelhardt and D. Michel, High Resolution Solid-State
and R. Willem, Eur. J. Inorg. Chem., 2004, 2908–2913;
(c) C. Camacho-Camacho, M. Biesemans, M. Van Poeck,
F. A. G. Mercier, R. Willem, K. Darriet-Jambert,
B. Jousseaume, T. Toupance, U. Schneider and U. Gerigk,
NMR of Silicates and Zeolites, John Wiley & Sons, Chiche-
ster, U.K., 1987; (b) S. Léonardelli, L. Facchini, C. Fretigny,
P. Tougne and A. P. Legrand, J. Am. Chem. Soc., 1992, 114,
6412–6418.
This journal is © The Royal Society of Chemistry 2013
Dalton Trans., 2013, 42, 9764–9770 | 9769

View Article Online
Paper
Dalton Transactions
18 P. Chevalier, R. J. P. Corriu, P. Delord, J. J. E. Moreau and 21 V. Pinoie, PhD dissertation, May 2009, Vrije
M. Wong Chi Man, New J. Chem., 1998, 423–433.
19 K. S. W. Sing, D. H. Everett, R. A. W. Haul, L. Moscou,
Universiteit
(Belgium).
Brussel,
Faculty
of
Engineering
R. A. Pierotti, J. Rouquerol and T. Siemieniewska, Pure 22 J. C. Pommier, M. Pereyre and J. Valade, C. R. Acad. Sci.,
Appl. Chem., 1985, 57, 603–619. 1965, 260, 6397–6399.
20 (a) W. Zhang, T. R. Pauly and T. J. Pinnavaia, Chem. Mater., 23 (a) E. P. Barrett, L. Joyner and P. P. Halenda, J. Am. Chem.
1997, 9, 2491–2498; (b) I. Park, Z. Wang and T. J. Pinnavaia,
Chem. Mater., 2005, 17, 383–386.
Soc., 1951, 73, 373–380; (b) J. P. Olivier, J. Porous Mater.,
1995, 2, 9–17.
9770 | Dalton Trans., 2013, 42, 9764–9770
This journal is © The Royal Society of Chemistry 2013