Catalytic Approach to Germanium-Functionalized Silsesquioxanes and Germasilsesquioxanes

Article abstract of DOI:10.1021/acs.organomet.7b00599

Silsesquioxanes have attracted considerable attention in recent years due to their unique hybrid structure and versatile properties. Herein, we report the first catalytic approach to the synthesis of completely and partially condensed germanium-functionalized silsesquioxanes as well as germasilsesquioxanes, mediated by scandium(III) triflate. We provide a solution for introducing germyl functionalities into various types of silsesquioxanes under mild conditions with excellent yields. This methodology turns out to be a highly efficient and selective synthesis route to obtaining novel germanium-containing silsesquioxanes. These new multielement POSS derivatives may have great potential for further applications as valuable multifunctional building blocks in material chemistry.

Full text of DOI:10.1021/acs.organomet.7b00599

Article
pubs.acs.org/Organometallics
Catalytic Approach to Germanium-Functionalized Silsesquioxanes
and Germasilsesquioxanes
Joanna Kazmierczak and Grzegorz Hreczycho*
́
Faculty of Chemistry, Adam Mickiewicz University in Poznan
́
́
*
S Supporting Information
ABSTRACT: Silsesquioxanes have attracted considerable atten-
tion in recent years due to their unique hybrid structure and
versatile properties. Herein, we report the first catalytic approach
to the synthesis of completely and partially condensed germanium-
functionalized silsesquioxanes as well as germasilsesquioxanes,
mediated by scandium(III) triflate. We provide a solution for
introducing germyl functionalities into various types of silsesquiox-
anes under mild conditions with excellent yields. This method-
ology turns out to be a highly efficient and selective synthesis route
to obtaining novel germanium-containing silsesquioxanes. These
new multielement POSS derivatives may have great potential for
further applications as valuable multifunctional building blocks in
material chemistry.
INTRODUCTION
industry, nanocomposite materials, pharmaceuticals and
■
18,19
others).
It has been reported that germanium-function-
Silsesquioxanes represent a class of organosilicon compounds
alized materials containing the Ge−O−Si moiety may show
of well-defined nanosized structure and versatile hybrid
20,21
1
−4
improved mechanical properties and thermal stability.
properties.
Due to their unique features, completely
Therefore, the germanium-containing POSS derivatives seem
to be particularly attractive for further applications and their
properties are still being investigated. Despite their great
potential, the number of reports regarding germanium-
functionalized silsesquioxanes and the methods for their
condensed as well as partially condensed functionalized
silsesquioxanes are of considerable interest and high relevance
in various fields of material chemistry and optoelectronics.
They are widely used as elastomers, optic and electronic
materials, hybrid adhesives, engineering materials, and
precursors of nanocomposites.
5
−9
22−25
5
−9
synthesis is still limited.
There are even fewer protocols
Moreover, a particularly
on the functionalization of incompletely condensed silsesquiox-
attractive group of POSS derivatives known as heterosilses-
quioxanes has attracted much attention owing to the presence
of heteroatoms (e.g., Ge, Sn, Al, B, P, transition metals, and
others) in addition to silicon and oxygen atoms in the POSS
26
anes with organogermanium groups.
Conventional methods for the synthesis of Ge−O−Si bond
are based on the condensation reaction of silanols/
chlorosilanes/alkoxysilanes with chloro-/alkoxygermananes or
1
0−13
skeleton.
For instance, the first germasilsesquioxane has
10,27
14
the cohydrolysis of chlorosilanes with chlorogermananes.
been synthesized by Feher and co-workers. Germasilsesquiox-
anes may serve as multielement precursors of hybrid
inorganic−organic materials. Furthermore, the presence of
germanium atoms in the POSS skeleton affects the dimensions
and parameters of the POSS framework. Germasilsesquioxanes
have been the subject of the experimental and computational
studies which have shown that the differences in the POSS
structure have a significant influence on the kinetics of trapping
Unfortunately, these reactions are restricted by the formation of
highly reactive and volatile byproducts (e.g., HCl). This
synthesis route involves the necessity of using moisture-
sensitive reagents and removal of corrosive byproducts.
Furthermore, it suffers from the lack of chemoselectivity and
low functional group tolerance. These significant drawbacks
limit the utility of the conventional methods. However, the
reports on the catalytic methods leading to the Ge−O−Si bond
formation are few. They are mainly based on B(C F ) -
15
and detrapping of atoms incorporated into the POSS cage.
Furthermore, the germanium-functionalized POSS compounds
containing Ge−O−Si bond in their structure may combine the
excellent physical, optical, and electrical properties of
silsesquioxanes and the enhanced features of germasiloxanes
e.g., higher refractive index, low dielectric constant, and
biocompatible properties).
6 5 3
catalyzed dealkylative coupling of hydrosilanes with alkox-
28
ygermananes or hydrogermananes with alkoxysilanes, the
coupling reaction of silanols with vinylgermananes catalyzed by
29
ruthenium(0) complexes or CpFe(CO) Me-catalyzed reac-
(
2
16,17
It is also worth noting that
organogermanium compounds have recently aroused much
Received: August 4, 2017
interest in various fields (e.g., as semiconductors in electronic
©
XXXX American Chemical Society
A
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1
6
tion of diphenylgermanane with silanes in DMF. Never-
theless, none of these reactions seems to be useful for
functionalization of commercially available POSS silanols.
This particularly interesting class of silsesquioxanes containing
silanol groups (Si−OH) plays an important role as easily
accessible precursors of other POSS derivatives.
methylallylgermananes providing the desired products in high
isolated yields (Table 1, entries 1−4).
Table 1. Synthesis of Monofunctional Derivatives in the
Reaction of POSS Monosilanol with 2-
Methylallylgermananes Catalyzed by Sc(OTf)3
a
To the best of our knowledge, the direct formation of Ge−
O−Si bond in all reported literature examples of Ge-
functionalized POSS derivatives and germasilsesquioxanes has
22−26
been achieved using conventional stoichiometric methods.
Moreover, there has been only one report regarding
incompletely condensed silsesquioxanes with organogerma-
26
nium functionalities. Marciniec and co-workers have recently
reported the synthesis of Ge-substituted incompletely con-
densed silsesquioxanes, however, their procedure does not
eliminate the formation of corrosive and reactive byproducts.
Our research group has recently found a new method for the
3
0−35
formation of E−O−Si bond (E = Si, Ge and B)
included
the O-metalation of silanols with 2-methylallylsilanes or 2-
methylallylgermananes in the presence of scandium(III)
30−33
trifluoromethanesulfonate.
Just recently, we have reported
the successful use of scandium(III) triflate in the O-silylation of
36
POSS silanols by 2-methylallylsilanes. Encouraged by these
results, we decided to extend this methodology for the
synthesis of germanium-functionalized silsesquioxanes as well
as POSS derivatives containing germanium atoms incorporated
into the POSS skeleton.
a
Reaction conditions: toluene, rt, 1 h, Sc(OTf) , catalyst loading 2 mol
, molar ratio of POSS/germanane = 1:4.
3
%
Thereafter, we decided to extend this methodology to the
functionalization of incompletely condensed silsesquioxanes:
POSS disilanol, trisilanol and double decker silsesquioxane
RESULTS
■
Herein, we report a successful extension of O-silylation of
POSS silanols to the synthesis of Ge-containing silsesquioxanes.
We present an efficient, selective and useful technique for the
formation of Ge−O−Si bond within POSS molecules. The aim
of this work was to examine the use of 2-methylallylgermananes
(
DDSQ) with four Si−OH groups (Scheme 1 and 2). All
Scheme 2. Synthesis of Digermasilsesquioxanes in the
Reaction of POSS Tetrasilanol (Double Decker
Silsesquioxane) with Bis(2-methylallyl)germananes
Catalyzed by Sc(OTf)3
as germylating reagents in Sc(OTf) -catalyzed O-germylation of
3
commercially available POSS silanols (Scheme 1).
First, we discovered that POSS monosilanol containing the
silanol group (Si−OH) successfully undergoes selective O-
germylation with 2-methylallylgermananes in the presence of 2
mol % of Sc(OTf) in toluene at room temperature with the
3
evolution of isobutylene as neutral and harmless byproduct
(Table 1). These optimal conditions were applied to various 2-
Scheme 1. Synthesis of Mono-, Di-, Trifunctional Ge-
Substituted POSS Derivatives and Germasilsesquioxanes
reactions were performed at room temperature, using toluene
as a solvent or a mixture of solvents CH CN/THF (v/v = 1:1)
3
when using double-decker derivatives due to their poor
solubility in toluene. The catalyst loading required for the O-
germylation of incompletely condensed silsesquioxanes con-
taining two, three or four Si−OH groups was 4 mol % of
Sc(OTf) to obtain desired products (Tables 2 and 3).
3
The purity of obtained compounds was determined by NMR
spectroscopy and elemental analysis. The conversion of
reagents was determined by NMR spectroscopy, in particular
29
29
by Si NMR spectroscopy (79 MHz, C D ). In the Si spectra
6
6
of the obtained products, we did not observe the peaks from
silicon atoms of silanol groups which proves the full conversion.
29
The Si spectra of the products as well as the reagents used for
the synthesis; POSS silanols are presented in the Supporting
Information.
B
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Table 2. Reactions of POSS Disilanol with 2-
reaction conditions, short time of reactions (1−2 h), and the
simplicity of experimental techniques. The coupling reaction of
POSS silanols and 2-methylallylgermananes proceeds with the
evolution of no corrosive or reactive byproducts. The only
byproduct formed in this reaction is a neutral and harmless
olefin-isobutylene.
Methylallylgermananes and Bis(2-methylallyl)germananes
,
ab
Catalyzed by Sc(OTf)3
It is worth noting that another advantage of this procedure is
the simplicity of separating the product from the catalyst as well
as the excess of germylating reagent by adding acetonitrile after
the reaction is completed. This particular solvent dissolves both
the catalyst and the excess of 2-methylallylgermanane but does
not dissolve POSS derivatives. The difference between the
solubility of Sc(OTf) and the silsesquioxanes in acetonitrile
3
allows obtaining the product as a precipitate.
Herein, we also report the first and efficient catalytic method
for capping the corner within incompletely condensed POSS
molecules with a germanium atom. We performed the corner-
capping reaction of POSS trisilanols with tris(2-methylallyl)-
germananes (Table 3, entries 11 and 12), POSS disilanol with
bis(2-methylallyl)germananes (Table 2, entries 7 and 8) and
double-decker silsesquioxane with bis(2-methylallyl)-
germananes (Scheme 2, entries 13 and 14). As a result, we
successfully synthesized various fully condensed germasilses-
quioxanes and digermasilsesquioxanes (Scheme 2). This
approach to germanium-capped POSS derivatives seems to be
an unprecedented catalytic method for the corner-capping
reaction and introducing germanium atoms into the POSS
skeleton.
a
Reaction conditions: toluene, rt, 2 h, Sc(OTf) , catalyst loading 4 mol
, molar ratio of POSS/germanane = 1:4. Reaction conditions:
3
b
%
toluene, rt, 2 h, Sc(OTf) , catalyst loading 4 mol %, molar ratio of
POSS/germanane = 1:1.
3
Moreover, we performed the reaction of POSS monolsilanol
with bis(2-methylallyl)germanane (Scheme 3). We successfully
Table 3. Reactions of POSS Trisilanol with 2-
Methylallylgermananes and Tris(2-methylallyl)germananes
,
ab
Catalyzed by Sc(OTf)3
Scheme 3. Synthesis of Ge-Functionalized Bridged POSS
Derivative 15
obtained Ge-functionalized bridged POSS compound consist-
ing of two POSS molecules of nanometer size linked together
by a organogermanium functionality (entry 15). The structure
was confirmed by NMR spectroscopy, elemental analysis, and
MS spectrometry.
It has been reported that bridged silsesquioxanes can be
applied as porous materials (e.g., gels with meso- and
macropores) owing to their unique three-dimensional
37
structure. When using metal triflate as a catalyst, both the
Lewis acid catalysis and the hidden Brønsted acid (TfOH)
catalysis may be competitive because triflic acid can be
38−40
generated in situ from triflates.
study, we also examined the difference in activity of Lewis acid
Sc(OTf) ) and Brønsted acid (TfOH) as catalysts in O-
During the course of our
(
3
germylation of POSS silanols (Scheme 4). We decided to check
which one is the active catalytic species in the coupling
reactions between POSS silanols and 2-methylallylgermananes.
Our first experiment was to check the performance of the
a
Reaction conditions: toluene, rt, 2 h, Sc(OTf) , catalyst loading 4 mol
, molar ratio of POSS/germanane = 1:6. Reaction conditions:
3
b
%
toluene, rt, 2 h, Sc(OTf) , catalyst loading 4 mol %, molar ratio of
POSS/germanane = 1:1.
3
same loading of pure TfOH (2−4 mol %), instead of Sc(OTf) ,
3
as the catalyst in the O-gemylation of POSS monosilanol and
partially condensed POSS trisilanol. Our experiments con-
firmed that TfOH can serve as the catalyst in this process but it
leads to partial decomposition of incompletely condensed
The important features of this procedure are high efficiency
and selectivity, low catalyst loading required (2−4 mol %), mild
C
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Article
Scheme 4. Difference in Activity of Sc(OTf) and TfOH as
Catalysts in O-Germylation of POSS Silanols
silsesquioxanes and introducing germanium atoms into the
POSS skeleton. This methodology has many favorable features
and advantages including mild reaction conditions, no corrosive
byproducts, short reaction time, low catalyst loading, and high
efficiency. We believe that it can be of great importance and
practical use for the functionalization of silsesquioxanes. We
also investigated the differences in the activity of the Lewis acid
3
(
Sc(OTf) ) and the hidden Brønsted acid (TfOH) as catalysts
3
in the O-germylation of silsesquioxanes. Our study proves that
Sc(OTf) is the active catalytic species in this reaction and does
3
not cause the decomposition of POSS molecules. The novel
multifunctional POSS derivatives reported in this paper can be
suitable as valuable precursors of various functional materials
with enhanced mechanical and thermal properties. They also
have the great potential for the application in many areas of
material chemistry, for instance as multielement building blocks
in the synthesis of hybrid materials.
silsesquioxanes. Then, we examined the Sc(OTf) -catalyzed
EXPERIMENTAL SECTION
Materials and Methods. The reagents and Sc(OTf) used for
experiments were purchased from Sigma-Aldrich Co. and ABCR
GmbH & Co. KG. Various 2-methylallylgermananes were synthesized
from chlorogermananes via the Grignard reaction. POSS compounds
were obtained from Hybrid Plastics. (Isobutyl monosilanol POSS was
synthesized according to the literature procedure.
for the synthesis of POSS monosilanol is shown in Supporting
Information. The structures of products were determined by mass
3
■
coupling reaction of POSS monosilanol and triethyl(2-
methylallyl)germanane in CH Cl with the addition of
3
2
2
cocatalytic amounts of tert-butyl chloride (2 mol % Sc(OTf)3
and 8 mol % t-BuCl) to generate the hidden Brønsted acid
(TfOH) released from scandium(III) triflate in halogenated
4
1,42
The procedure
solvents. We discovered that the reaction of POSS trisilanol
with 2-methylallylgermanane in CH Cl in the presence of
2
2
Sc(OTf)3 and t-BuCl leads to partial decomposition of
incompletely condensed silsesquioxanes. The decomposition
of POSS compounds was observed in the NMR spectra which
are presented in the Supplement Information. We also
investigated this coupling reaction catalyzed by Sc(OTf)3
with the Brønsted base 2,6-di-tert-butylpyridine (DTBP) (2
1
13
spectrometry and NMR spectroscopy. H NMR (400 MHz),
C
29
NMR (101 MHz), Si NMR (79 MHz) spectra were recorded on a
Varian XL 300 spectrometer using C D as the solvent.
6
6
Synthetic Procedures. General Procedure for the Synthesis of
Completely Condensed Monofunctionalized POSS Derivatives 1−4.
A mixture of 1 mmol of POSS monosilanol, 4 mmol of 2-
methylallylgermanane, and anhydrous toluene (2 mL) was placed in
a 50 mL one-necked round-bottomed flask equipped with a magnetic
mol % Sc(OTf) and 2 mol % DTBP in the case of POSS
3
monosilanol and 4 mol % Sc(OTf) and 4 mol % DTBP in the
3
stirring bar. Next, 0.02 mmol (2 mol %) of Sc(OTf) was added, and
3
case of POSS trisilanol). DTBP was added in order to bind/
coordinate the hidden Brønsted acid. In this experiment, we
obtained products in similarly good yields which proves that
the Lewis acid catalysis seems to be the favorable catalytic
pathway. These experiments lead to the conclusion that our
the reaction mixture was stirred at room temperature for 1 h. After
this, the solvent was evaporated under vacuum, and the product was
separated from the catalyst by adding acetonitrile which dissolved both
the catalyst and the excess of 2-methylallylgermanane. The product
was obtained as a precipitate which was then filtered off or as oil which
was separated from acetonitrile to give corresponding compounds 1−
optimized reaction conditions (the use of Sc(OTf) as a catalyst
3
4
.
and toluene as a solvent) enable the highly selective and
efficient O-germylation of POSS silanols, especially the
incompletely condensed silsesquioxanes. Moreover, the main
advantages of using Sc(OTf)3 over pure TfOH are the
simplicity of experimental techniques and the lack of POSS
decomposition during the catalytic cycle.
General Procedure for the Synthesis of Incompletely Condensed
Difunctional Silsesquioxane Derivatives 5 and 6. A mixture of 1
mmol of POSS disilanol, 4 mmol of 2-methylallylgermanane, and
anhydrous toluene (2 mL) was placed in a 50 mL one-necked round-
bottomed flask equipped with a magnetic stirring bar. Then, 0.04
mmol (4 mol %) of Sc(OTf) was added, and the reaction mixture was
3
As a result of our study, we obtained a series of completely
and partially condensed POSS molecules substituted with
organogermanium functional groups. We also synthesized the
completely condensed germasilsesquioxanes containing germa-
nium atoms in the POSS core. All newly obtained compounds
were characterized by H, C, and Si NMR spectroscopy and
elemental analysis. These novel POSS derivatives can be of high
relevance because multielement compounds turn out to be
beneficial and useful in material science. Therefore, they may
have significant potential for further applications.
In conclusion, we present the first catalytic method for the
synthesis of germanium-functionalized silsesquioxanes. This
convenient synthesis route allows us to obtain germasilses-
quioxanes and Ge-containing completely and partially con-
densed POSS derivatives with excellent yields and high
selectivity. Moreover, our procedure provides a highly effective
method for capping the corner of incompletely condensed
stirred at room temperature for 2 h. After this, the solvent was
evaporated under vacuum, and the product was separated from the
catalyst by adding acetonitrile which dissolved both the catalyst and
the excess of 2-methylallylgermanane. The product was obtained as a
precipitate which was then filtered off or as oil which was separated
from acetonitrile to give corresponding compounds 5 and 6.
General Procedure for the Synthesis of Completely Condensed
Germasilsesquioxanes 7 and 8. A mixture of 1 mmol of POSS
disilanol, 1 mmol of bis(2-methylallyl)germanane, and anhydrous
toluene (2 mL) was placed in a 50 mL one-necked round-bottomed
flask equipped with a magnetic stirring bar. Then, 0.04 mmol (4 mol
1
13
29
%
) of Sc(OTf) was added, and the reaction mixture was stirred at
3
room temperature for 2 h. After this, the solvent was evaporated under
vacuum, and the product was separated from the catalyst by adding
acetonitrile. The product was obtained as a precipitate which was then
filtered off or as oil which was separated from acetonitrile to give
corresponding compounds 7 and 8.
General Procedure for the Synthesis of Incompletely Condensed
Trifunctional Silsesquioxane Derivatives 9 and 10. A mixture of 1
D
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mmol of POSS trisilanol, 6 mmol of 2-methylallylgermanane, and
anhydrous toluene (2 mL) was placed in a 50 mL one-necked round-
bottomed flask equipped with a magnetic stirring bar. Then, 0.04
(2) Yan, Z.; Xu, H.; Guang, S.; Zhao, X.; Fan, W.; Liu, X. Y. Adv.
Funct. Mater. 2012, 22, 345−352.
(3) Ayandele, E.; Sarkar, B.; Alexandridis, P. Nanomaterials 2012, 2,
445−475.
mmol (4 mol %) of Sc(OTf) was added, and the reaction mixture was
3
stirred at room temperature for 2 h. After this, the solvent was
evaporated under vacuum, and the product was separated from the
catalyst by adding acetonitrile which dissolved both the catalyst and
the excess of 2-methylallylgermanane. The product was obtained as a
precipitate which was then filtered off or as oil which was separated
from acetonitrile to give corresponding compounds 9 and 10.
(4) Phillips, S. H.; Haddad, T. S.; Tomczak, S. J. Curr. Opin. Solid
State Mater. Sci. 2004, 8, 21−29.
(5) Olivero, F.; Carniato, F.; Bisio, C.; Marchese, L. J. J. Mater. Chem.
2012, 22, 25254−25261.
(6) Chan, K. L.; Sonar, P.; Sellinger, A. J. Mater. Chem. 2009, 19,
9
103−9120.
7) Yang, X.; Froehlich, J. D.; Chae, H. S.; Harding, B. T.; Li, S.;
Mochizuki, A.; Jabbour, G. E. Chem. Mater. 2010, 22, 4776−4782.
8) Kamino, B. A.; Bender, T. P. Chem. Soc. Rev. 2013, 42, 5119−
130.
9) Seurer, B.; Coughlin, E. B. Macromol. Chem. Phys. 2008, 209,
198−1209.
10) Murugavel, R.; Voigt, A.; Walawalkar, M. G.; Roesky, H. W.
Chem. Rev. 1996, 96, 2205−2236.
11) Feher, F. J.; Budzichowski, T. A.; Ziller, J. W. Inorg. Chem. 1997,
6, 4082−4086.
12) Lorenz, V.; Edelmann, F. T. Advances in Organometallic
Chemistry. Metallasilsesquioxanes; Elsevier: Magdeburg, Germany,
005; pp 101−153.
13) Levitsky, M. M.; Yalymov, A. I.; Kulakova, A. N.; Petrov, A. A.;
Bilyachenko, A. N. J. Mol. Catal. A: Chem. 2017, 426, 297−304.
14) Feher, F. J.; Newman, D. A.; Walzer, J. F. J. Am. Chem. Soc.
989, 111, 1741−1748.
15) Pach, M.; Macrae, R. M.; Carmichael, I. J. Am. Chem. Soc. 2006,
28, 6111−6125.
16) Kamitani, M.; Fukumoto, K.; Tada, R.; Itazaki, M.; Nakazawa,
General Procedure for the Synthesis of Completely Condensed
Germasilsesguioxanes 11 and 12. A mixture of 1 mmol of POSS
trisilanol, 1 mmol of tris(2-methylallyl)germanane, and anhydrous
toluene (2 mL) was placed in a 50 mL one-necked round-bottomed
flask equipped with a magnetic stirring bar. Then, 0.04 mmol (4 mol
(
(
5
(
1
%
) of Sc(OTf) was added, and the reaction mixture was stirred at
3
room temperature for 2 h. After this, the solvent was evaporated under
vacuum, and the product was separated from the catalyst by adding
acetonitrile. The product was obtained as a precipitate which was then
filtered off or as oil which was separated from acetonitrile to give
corresponding compounds 11 and 12.
(
(
3
(
General Procedure for the Synthesis of Digermasilsesquioxanes
3 and 14. To a 50 mL one-necked round-bottomed flask were added
1
2
(
1
mmol of POSS tetrasilanol (DDSQ), 2 mmol of bis(2-methylallyl)-
germanane, and 6 mL of the mixture of CH CN/THF (ratio v/v =
3
1
:1). Then, 0.04 mmol (4 mol %) of Sc(OTf) was added, and the
3
(
1
(
1
reaction mixture was stirred at room temperature for 2 h. After this,
the solvent was evaporated under vacuum, and the product was
separated from the catalyst by adding acetonitrile. The product was
obtained as a precipitate which was then filtered off to give products
̈
(
1
3 and 14.
H. Organometallics 2012, 31, 2957−2960.
(17) Risen, W. M.; Wang, Y. Z., Jr.; Honore, A. U.S. Patent 2001/
6248852, 2001.
General Procedure for Obtaining the Bridged Ge-Functionalized
POSS Derivative 15. A mixture of 2 mmol of POSS monosilanol, 1
mmol of bis(2-methylallyl)germanane, and anhydrous toluene (2 mL)
was placed in a 50 mL one-necked round-bottomed flask equipped
with a magnetic stirring bar. Next, 0.04 mmol (4 mol %) of Sc(OTf)3
was added, and the reaction mixture was stirred at room temperature
for 2 h. After this, the solvent was evaporated under vacuum, and the
product was separated from the catalyst by adding acetonitrile which
dissolved the catalyst. The product was obtained as a precipitate which
was then filtered off to give compound 15.
(18) Gadzała-Kopciuch, R.; Pypowski, K.; Chrzasc
Crit. Rev. Anal. Chem. 2010, 40, 187−193.
́
ik, I.; Kluska, M.
(19) Carpenter, J.; Lukehart, M.; Henderson, D. O.; Mu, R.; Jones, B.
D.; Glosser, R.; Stock, S. R.; Wittig, J. E.; Zhu, J. G. Chem. Mater. 1996,
8, 1268−1274.
(20) Lin, Q.; Bu, X.; Mao, C.; Zhao, X.; Sasan, K.; Feng, P. J. Am.
Chem. Soc. 2015, 137, 6184−6187.
(21) Nedez, C.; Choplin, A.; Basset, J. M.; Benazzi, E. Inorg. Chem.
ASSOCIATED CONTENT
Supporting Information
The Supporting Information is available free of charge on the
ACS Publications website at DOI: 10.1021/acs.organo-
met.7b00599.
1994, 33, 1094−1098.
22) Rzonsowska, M.; Dudziec, B.; Marciniec, B. Dalton Trans. 2016,
5, 17187−17194.
23) Frąckowiak, D.; Zak, P.; Spol
Organometallics 2015, 34, 3950−3958.
(24) Zak, P.; Frąckowiak, D.; Grzelak, M.; Bołt, M.; Kubicki, M.;
Marciniec, B. Adv. Synth. Catal. 2016, 358, 3265−3276.
■
(
4
(
*
S
̇
́
nik, G.; Pyziak, M.; Marciniec, B.
̇
Details concerning experimental techniques and NMR
spectra of isolated products (PDF)
̇
(
25) Frąckowiak, D.; Zak, P.; Marciniec, B. U.S. Patent 2016/
249167, 2016.
26) Grzelak, M.; Frąckowiak, D.; Marciniec, B. Eur. J. Inorg. Chem.
2017, 2017, 3337−3342.
27) Puff, H.; Bockmann, M. P.; Kok, T. R.; Schuh, W. J. Organomet.
Chem. 1984, 268, 197−206.
28) Ignatovich, L.; Muravenko, V.; Grinberga, S.; Lukevics, E. Chem.
9
(
AUTHOR INFORMATION
Corresponding Author
E-mail: g.h@amu.edu.pl.
■
*
(
(
ORCID
Heterocycl. Compd. 2006, 42, 268−271.
29) Hreczycho, G.; Frąckowiak, D.; Pawluc,
Tetrahedron Lett. 2011, 52, 74−76.
30) Hreczycho, G.; Kucinski, K.; Pawluc,
Organometallics 2013, 32, 5001−5004.
31) Hreczycho, G.; Pawluc, P.; Marciniec, B. New J. Chem. 2011, 35,
(
́
P.; Marciniec, B.
Grzegorz Hreczycho: 0000-0002-3606-7114
Notes
The authors declare no competing financial interest.
(
́
́
P.; Marciniec, B.
(
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ACKNOWLEDGMENTS
2743−2746.
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(
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32) Hreczycho, G. Eur. J. Inorg. Chem. 2015, 67−72.
33) Kucinski, K.; Hreczycho, H. ChemCatChem 2017, 9, 1868−
This work was supported by a National Science Centre Grant
UMO-2015/19/B/ST5/00240.
́
1
885.
(
34) Frackowiak, D.; Walkowiak, J.; Hreczycho, G.; Marciniec, B. Eur.
J. Inorg. Chem. 2014, 3216−3220.
(35) Kucinski, K.; Hreczycho, G. ChemSusChem 2017,
DOI: 10.1002/cssc.201701648.
REFERENCES
■
(
1) Cordes, D. B.; Lickiss, P. D.; Rataboul, F. Chem. Rev. 2010, 110,
́
2
081−2173.
E
DOI: 10.1021/acs.organomet.7b00599
Organometallics XXXX, XXX, XXX−XXX

Organometallics
Article
(
5
(
36) Kazm
6, 9337.
37) Kaneko, Y.; Coughlin, E. B.; Gunji, T.; Itoh, M.; Matsukawa, K.;
Naka, K. Int. J. Polym. Sci. 2012, 2012, 1−2.
38) Sharma, I.; Wurst, J. M.; Tan, D. S. Org. Lett. 2014, 16, 2474−
477.
́
́
ierczak, J.; Kucinski, K.; Hreczycho, G. Inorg. Chem. 2017,
(
2
(
(
39) Dzudza, A.; Marks, T. J. Chem. - Eur. J. 2010, 16, 3403−3422.
40) Dang, T. T.; Boeck, F.; Hintermann, L. J. Org. Chem. 2011, 76,
9
(
353−9361.
41) Roesky, H. W. Efficient Methods for Preparing Silicon Compounds;
Elsevier: Gottingen, Germany, 2016; pp 143−159.
42) Duchateau, R.; Abbenhuis, H. C. L.; van Santen, R. A.; Thiele, S.
K. H.; van Tol, M. F. H. Organometallics 1998, 17, 5222−5224.
̈
(
F
DOI: 10.1021/acs.organomet.7b00599
Organometallics XXXX, XXX, XXX−XXX