Homoleptic chelating N-heterocyclic carbene complexes of palladium immobilized within the pores of SBA-15/IL (NHC-Pd@SBA-15/IL) as heterogeneous catalyst for Hiyama reaction

Article abstract of DOI:10.1016/j.jorganchem.2015.05.019

In this work, SBA-15 was selected as a support for the homoleptic chelating N-heterocyclic carbene complexes of palladium. Here, Pd²⁺ ions were coordinated to N-heterocyclic carbene (NHC-Pd) which also contain ionic liquid. Then, this NHC-Pd@SBA-15/IL catalyst (NHC-Pd active part of the catalyst) was successfully applied in the catalysis of Hiyama coupling reaction with lower mol% Pd rather to previously reported literatures. The role of TBAF and Cs₂CO₃ in the decrease of Pd mol% was crucial. Recyclability test showed a successful reusability for 5 runs. Simultaneous application of TBAF and NaOH did destroy the silica structure of SBA-15 in the first run.

Full text of DOI:10.1016/j.jorganchem.2015.05.019

Accepted Manuscript
Homoleptic chelating N-heterocyclic carbene complexes of palladium immobilized
within the pores of SBA-15/IL (NHC-Pd@SBA-15/IL) as heterogeneous catalyst for
Hiyama reaction
Sadegh Rostamnia, Habib Golchin Hossieni, Esmail Doustkhah
PII:
S0022-328X(15)00301-0
10.1016/j.jorganchem.2015.05.019
JOM 19057
DOI:
Reference:
To appear in: Journal of Organometallic Chemistry
Received Date: 29 January 2015
Revised Date: 9 April 2015
Accepted Date: 2 May 2015
Please cite this article as: S. Rostamnia, H.G. Hossieni, E. Doustkhah, Homoleptic chelating N-
heterocyclic carbene complexes of palladium immobilized within the pores of SBA-15/IL (NHC-
Pd@SBA-15/IL) as heterogeneous catalyst for Hiyama reaction, Journal of Organometallic Chemistry
(2015), doi: 10.1016/j.jorganchem.2015.05.019.
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ACCEPTED MANUSCRIPT

ACCEPTED MANUSCRIPT
Homoleptic chelating N-heterocyclic carbene complexes of palladium immobilized within
the pores of SBA-15/IL (NHC-Pd@SBA-15/IL) as heterogeneous catalyst for Hiyama
reaction
Sadegh Rostamnia,* Habib Golchin Hossieni, Esmail Doustkhah
Organic and Nano Group (ONG), Department of Chemistry, Faculty of Science, University of
Maragheh, P.O. Box. 55181-83111, Maragheh, Iran. Fax: +98 (41) 37276066. E-
mail:srostamnia@gmail.com; rostamnia@maragheh.ac.ir
Abstract: In this work, SBA-15 was selected as a support for the homoleptic chelating N-
heterocyclic carbene complexes of palladium. Here, Pd2+ ions were coordinated to N-
heterocyclic carbene (NHC-Pd) which also contain ionic liquid. Then, this NHC-Pd@SBA-15/IL
catalyst (NHC-Pd active part of the catalyst) was successfully applied in the catalysis of Hiyama
coupling reaction with lower mol% Pd rather to previously reported literatures. The role of
TBAF and Cs2CO3 in the decrease of Pd mol% was crucial. Recyclability test showed a
successful reusability for 5 runs. Simultaneous application of TBAF and NaOH did destroy the
silica structure of SBA-15 in the first run.
Keywords: Hiyama reaction; heterocyclic carbene; ionic liquid; NHC-Pd@SBA-15/IL;
homoleptic carbene.
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Introduction
Ionic liquids play an important role in greening chemical protocols and sustainable chemistry.
Nowadays, many types of Ionic liquids are available with variable cations and anions. These
liquids are a great candidate against volatile organic compounds (VOC) which are used for
example as solvent. The key step in ionic liquids is to support them to solid surface to generate a
recoverable and non-leachable and reusable. By changing one of the counter ions with
catalytically active ions, an efficient and ionic liquid-based catalyst can be obtained. Recently,
we supported N-methylimidazole inside the pore channels of SBA-15-Pr-Cl and then replaced
-
chloride ion with HSO4 , a Bronsted acid, to generate a Bronsted acid-type ionic liquid supported
SBA-15. Karimi et al., extensively synthesized various SBA-15 and periodic mesoporous
organosilica (PMO) supported ionic liquids with variable catalytically active anions [1-3]. By
supporting or confining ILs inside these pore channels, diffusability and mass transfer can be
affected [4, 5]. Also, ILs are powerful tools for synthesis and stabilization of nanoparticles [6, 7].
For example, they are used for generation of Pd nanoparticles and preventing it from aggregation
and generation of black Pd [8, 9]. One of the capabilities of imidazolium is to be act as a
carbene-based ligand for various types of transition metals such as Pd2+ [10].
Hiyama coupling reaction [11-13], corresponding of other organometallic reactions (e.g. Stille,
Suzuki-Miyaura) has attained some prevailing advantages owing to the fact that organosilanes
have low toxicity, facile handling, and stability in most chemical media. However due to the low
reactivity of organosilanes, the reaction generally proceeds by primary activation of C-Si bond
with fluoride anions [14, 15] or Na/KOH [16-18] transmetallation step. Several Pd containing
catalysts are currently reported for the catalysis of Hiyama reaction [19-21]. Among them
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phosphine-based ligands are the most common which are expensive, toxic and homogeneous
[22]. Therefore, demands for an available, highly efficient phosphine-free ligands, non-toxic, and
recyclable heterogeneous catalytic systems is still under the consideration. In addition, Hiyama
coupling reaction generally requires more catalytic amount of Pd when compared to other types
of cross-couplings such as Suzuki-Miyaura. Therefore, main part of Pd may be exposed to
leaching from heterogeneous supports. We found that by simultaneous application of both
fluoride ion and Cs2CO3 can raise the catalytic activity and decrease the catalytic amount of
NHC-Pd/SBA-15/IL. We believe that TBAF and Cs2CO3 can have complementary effect on the
activation of C-Si bond.
Results and Discussion
For the use of heterogeneous system, NHC-Pd complexes have mainly been immobilized on
silica-based supports. Karimi and Enders synthesized a bidentic NHC-Pd complex in solution
and then immobilized it on silica gel, which was successfully applied to the Heck reaction [2].
Yang’s group prepared a silica-based SBA-16 palladium pre-catalyst with same bidentic NHC-
Pd complex for the Suzuki and Heck reaction [5]. In these case, they anchored a mixture of
imidazolium ionic liquid/NHC-Pd precursor, which was synthesized in solution, on silica gel or
SBA-16 silica-based material. As an ongoing research in nanoporous silica materials [23-29], we
herein, synthesized mesoporous silica SBA-15 by hydrolysis of TEOS in acidic conditions in the
presence of P123, a triblock copolymer as a structure directing agent, for grafting of imidazolium
ionic liquid/NHC-Pd by one-pot method. Based on this method, first the N-methylimidazole
(NMI) reacted with 3-chloropropyltrimethoxysilane (CPTMS) moiety to produce imidazolium
chloride-based ionic liquid in solution phase. Afterwards, a submolar amount of PdCl2 was
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added to IL to produce a mixture of N-heterocyclic carbene-Pd and ionic liquid [see ref 5].
Finally, based on Karimi and Yang’s method, this NHC-Pd and IL mixture supported on SBA-15
(NHC-Pd/SBA-15/IL) as a catalyst for further studies (Scheme 1).
Scheme 1. Schematic synthesis pathway of NHC-Pd/SBA-15/IL.
TEM images show a hexagonal mesochannels of NHC-Pd/SBA-15/IL which confirms the
maintenance of SBA-15 structure after modification and carbene formation. SEM image of
NHC-Pd/SBA-15/IL show its morphology after production. In fact, this morphology is similar to
morphology of SBA-15 which indicates that after modification and NHC-Pd formation, the
morphology is still intact. Calculated average pore size for NHC-Pd/SBA-15/IL was around 6.5
nm. Also, EDS analysis was performed for the catalyst. Based on this analysis, C, Pd, O, and Si
atoms were exist in the structure of NHC-Pd/SBA-15/IL which exhibit the successful grafting of
Pd to SBA-15. Wt% of Pd in NHC-Pd/SBA-15/IL was calculated by ICP-AES. According to
this, the wt% of Pd was 0.81%.
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Figure 1. Characterization of NHC-Pd/SBA-15/IL: a) SEM image; b) SEM image; c) EDS
analysis and d) TEM image after first run in the presence of TBAF/NaOH.
FT-IR analyses were obtained in every step of NHC-Pd/SBA-15/IL synthesis. A peak at 2925
cm-1 shows the aliphatic chain of propyl moiety. A broad band in all spectrums relates to
stretching of surface SiO-H at ~1100 cm-1. In Fig. 2, the FT-IR spectroscopy of NHC-Pd/SBA-
15/IL exhibited new peaks around 1572 cm-1, compared with the FT-IR spectroscopy of SBA-
15/PrCl. This peak corresponded to the ring vibration of the imidazole ring.
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Figure 2. FT-IR spectrums of SBA-15-PrCl, SBA-15/IL, and NHC-Pd/SBA-15/IL.
This catalyst was studied in Hiyama cross-coupling reaction of aryl halides and
phenyltrimethoxysilane (PTMS). Various conditions were tested by a model reaction (p-
bromoacetophenone and PTMS) and under an optimized conditions, NHC-Pd/SBA-15/IL was
found to be efficient in the catalysis of Hiyama coupling reaction. As mentioned, due to lower
activity of C-Si bond, it needs to be activated by F- or OH- to generate a remarkable yield.
However, in many cases under such conditions, the reaction progress requires more catalytic
amount of Pd in Hiyama reaction in comparison with other corresponding cross-coupling
reactions (Suzuki-Miyaura and stile reactions). To decrease this the catalytic amount of Pd in the
reaction, we simultaneously used TBAF and a weak base (Cs2CO3) which generates a small
amount of OH- in the activation of C-Si bond. By this approach, the catalytic amount of Pd
decreased from 1 mol% to 0.8 mol%. Of course in the case of NaOH, the yield of reaction was
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higher than Cs2CO3. However, in the presence of NaOH, it led to remarkable leaching and
collapse of silica pore walls of SBA-15 in the first run.
Table 1. Optimizing the model reaction conditions catalyzed by NHC-Pd/SBA-15/IL. a
Entry
Catalyst
F-
OH-
Solvent
Base
T/t
Yield
(%)b
20
-
45
species species
(oC/h)
100/12
100/16
1
2
SBA-NHC-Pd TBAF
SBA-NHC-Pd NaF
SBA-NHC-Pd TBAF
SBA-NHC-Pd
SBA-NHC-Pd
-
-
-
H2O
H2O
DMF
-
-
3
DABCO 100/10
DABCO
DBU
4 g
5
NaF
KF
Cs2CO3
-
NaOH
H2O:diox
Toluene
H2O:diox
H2O:diox
H2O:diox
Dioxane
H2O:diox
Dioxane
H2O:PEG
Toluene
80/10
100/12 trace
6
6 g
7 g
8g
9
SBA-NHC-Pd TBAF
-
-
-
-
80/8
80/8
80/10
80/10
80/10
80/4
95
90
38
73
15
87
71
88
SBA-NHC-Pd TBAF Cs2CO3
SBA-NHC-Pd TBAF
SBA-NHC-Pd TBAF Cs2CO3
SBA-NHC-Pd
Pd(OAc)2
-
10g
11c
12d
13e
-
Cs2CO3
-
TBAF
-
TBAF
-
NaOH
-
DABCO
Pd(OAc)2
-
-
100/2
120/5
NHC-Pdf
a Reaction conditions: 1 mmol of 4-bromoacetophenone, 2 mmol of phenyltrimethoxysilane, 0.8
mol% of IL@SBA-15-NHC-Pd, 2 mmol of F- species, 1 mmol of Cs2CO3 species, 10 mol% of
b
c
base if needed; at variable reaction times and temperatures. Isolated yields, Abstracted from
ref. [15], Abstracted from ref. [30], Abstracted from ref. [31]. The catalyst has different
structure with homogeneous nature; mol% of Pd was 0.5% for ArCl. g H2O:dioxane (1:2)
d
e
f
The obtained TEM images from NHC-Pd/SBA-15/IL in the first run indicate that simultaneous
use of NaOH and TBAF totally have destructive effect on the structure of silica SBA-15.
Therefore, these conditions were not suitable method for the catalysis of Hiyama coupling
reaction by NHC-Pd/SBA-15/IL. In fact, a silica structure can’t be stable at very basic conditions
or in the presence of concentrated F-. However, when NaOH was replaced with Cs2CO3, a
destructive effect on the structure of SBA-15 was not observed. Also, to minimize the destructive
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effect of TBAF on silica, the catalyst was added to the reaction mixture after PTMS activation
(Figure 1d).
Table 2. Synthesis of biaryls over Hiyama reaction. a
Entry
I/Br
Br
Br
Br
Br
Br
Br
Br
I
R
H
T (h)
Yield (%)
1
2
3
4
5
6
7
8
9
8
8
6
7
8
6
5
8
8
90
82
92
83
90
92
93
95
94
2-OMe
4-COMe
2-NO2
4-Me
3-NO2
4-NO2
H
I
4-COMe
a Reaction conditions: aryl halide (1 mmol), triemthoxyphenylsilane (2 mmol), 0.8 mol % of Pd,
and 1 mmol of TBAF, and one mmol of Cs2CO3 at 80 ºC in 2 mL dioxane:H2O (2:1).
Chemoselectivity of the method was also tested by reacting p-bromobenzaldehyde with
phenyltrimethoxysilane under the optimized conditions. Under the suggested optimized reaction
conditions, it only produced biaryl product and no corresponding benzophenone derivative was
not observed (Scheme 2). This observation demonstrates the chemoselectivity of NHC-Pd/SBA-
15/IL under the optimized reaction conditions.
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Scheme 2. Chemoselectivity of Hiyama coupling under the reaction conditions.
This method had the least effect on the catalyst, since the catalyst was recycled for 5 successful
runs (Figure 3). In this study, NHC-Pd/SBA-15/IL could be recycled for 5 runs with no
significant decrease in the yields. However, after 6th runs, due to the fact that the ordered
mesoporous silica (SBA-15) which was as a support undergoes remarkable destruction in
structure, a significant drop in the yield can be observed. Figure 3 shows TEM image of NHC-
Pd/SBA-15/IL in 6th run in which the silica support is destroyed. Its reason can be related to the
destructive effect of F- on the silica structure. Upon catalyst recovery in each run, the catalyst
was washed with DCM (or diethyl ether) and reused in the next cycle. No Pd was detected in
reaction solution until 5th run (analyzing by ICP-AES), confirming the good stability of the
systems under the investigated reaction conditions.
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Fig. 3. a) Recyclability study of NHC-Pd/SBA-15/IL in Hiyama reaction (scale: 10 mmol) and b)
its TEM image after 6th run.
A possible mechanism can be predicted for the catalysis of Hiyama cross-coupling reaction
through NHC-Pd/SBA-15/IL according to previously reported literatures [32, 33]. In this
proposed mechanism, Pd(0) primarily undergoes an oxidative addition with arylhalide 1 to
generate intermediate 4 and then the activated C-Si bond in compound 3 (over Cs2CO3 and
TBAF) under transmetalation adds to 4 and finally, the product is generated by further reductive
elimination, and the Pd(0) regenerates to next catalytic cycle (Scheme 3).
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Scheme 3. NHC-Pd/SBA-15/IL catalysis proposed mechanism for Hiyama coupling.
Experimental and Catalyst Characterization
Pluronic P123 copolymer (EO20PO70EO20), (3-chloropropyl)trimethoxysilane (CPTMS) and
PdCl2 were purchased from Merck (Germany). Tetraethyl orthosilicate, N-methylimidazole and
various aryl bromides were obtained from Fluka (Switzerland) and used without further
purification. Thin linear chromatography (TLC) was used for monitoring the reaction
completion.
Preparation of NHC-Pd/SBA-15/IL:
Mesoporous SBA-15 was synthesized according to our previous method [26-28]. Synthesis of
NHC-Pd/SBA-15/IL was synthesized according to literature [2,5] with slight change. In a dry
and degased (with Ar) flask, CPTMS (2 mmol) was added to N-methylimidazole (2.2 mmol)
without any solvent. After being stirred at 100 ◦C for 40 h, the resulting solvent-free mixture was
allowed to cool to 25◦C, was washed with dry toluene. The obtained ionic liquid was a yellowish
sticky liquids. Then in a dry flask, PdCl2 (0.006 g) was added to the synthesized ionic liquid. The
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mixture was stirred at 60 ◦C for 8 h and then at 100 ◦C for 3 h under Ar atmosphere. The system
was attached to the vacuum system for 2 and was then allowed to cool down to 25◦C, affording a
pale green-yellow solution of NHC-Pd complex in ionic liquid (NHC-Pd/IL). Then, 1 g of SBA-
15 was dispersed in a mixture of toluene/EtOH (50 mL) for 30 min. Afterward, as synthesized
o
NHC-Pd/IL mixture was added to the SBA-15 mixture and allowed to stir for 20 h at 70 C.
Finally, the solid was filtered and washed with dichloromethane (DCM).
General synthesis of biaryls through Hiyama coupling reaction:
For catalyst test, in a typical method, 1 mmol of aryl halide, 2 mmol of PTMS, 1 mmol of TBAF,
1 mmol of Cs2CO3, 0.3 mol% (0.10 g) of NHC-Pd/SBA-15/IL were mixed to react in 2 mL
o
dioxane:H2O (2:1) at 80 C for 8 h. afterwards, the reaction mixture was cooled to room
temperature and the catalyst was separated by filtration and with DCM. Work-up step was
performed by DCM (organic solvent) and distilled water. Then, the organic solution was
evaporated and the residue was purified by column chromatography and the product. All
obtained products are known and characterized and compared with physical and instrumental
methods.
NMR data for selected compounds:
4-Methylbiphenyl: White solid, mp: 45-47 oC. 1H NMR (300 MHz, CDCl3):
δ
= 7.28-7.63 (m,
Ar-H, 9 H), 2.44 (s, CH3, 3 H). 13C NMR (75 MHz, CDCl3):
128.73, 127.23, 127.18, 127.00, 21.11.
δ = 141.18, 138.38, 137.03, 129.50,
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o
Biphenyl: White solid, mp: 71-72 C. 1H NMR (300 MHz, CDCl3):
δ
= 7.62-7.65 (m, 4 H),
7.46-7.50 (m, 4 H), 7.38-7.40 (m, 2 H). 13C NMR (75 MHz, CDCl3):
127.19.
δ = 141.25, 128.77, 127.27,
1-Biphenyl-4-yl-ethanone: White solid, mp: 121-123 oC. 1H NMR (300 MHz, CDCl3):
8.06 (m, 2 H), 7.63-7.78 (m, 4 H), 7.41-7.50 (m, 3 H), 2.65 (s, 3 H). 13C NMR (75 MHz, CDCl3):
δ = 8.03-
δ
= 197.83, 145.80, 139.87, 135.85, 128.95, 128.92, 128.23 127.27, 127.23, 26.65.
4-Methoxybiphenyl: White solid, mp: 89-91 oC. 1H NMR (300 MHz, CDCl3):
δ
= 7.57-7.61 (m,
13
4 H), 7.44-7.48 (m, 2 H), 7.32-7.37 (m, 1 H), 7.01-7.04 (m, 2 H), 3.88 (s, 3 H); CNMR (75
MHz, CDCl3):
2-Methoxylbiphenyl: Colorless viscous liquid. 1H NMR (300 MHz, CDCl3):
7.50 (m, 2 H), 7.41-7.43 (m, 3 H), 7.05-7.14 (m, 2 H), 3.88 (s, 3 H); 13C NMR (75 MHz, CDCl3):
δ = 159.19, 140.86, 133.80, 128.75, 128.18, 126.76, 126.69, 114.24, 55.35.
δ
= 7.62 (m, 2 H),
δ
= 156.54, 138.63, 130.96, 130.79, 129.63, 128.83, 128.05, 126.98, 120.91, 111.31, 55.59.
2-Methyl-biphenyl: Colorless oil. 1H NMR (300 MHz, CDCl3):
δ = 7.26-8.46 (m, 9 H), 1.26 (s,
13
3 H). C NMR (75 MHz, CDCl3):
127.15, 122.02, 121.95, 29.69.
δ = 142.87, 138.66, 133.04, 129.71, 129.16, 128.54, 127.95,
3-Methyl-4'-methoxy-biphenyl: Colorless oil. 1H NMR (300 MHz, CDCl3):
H), 3.87 (s, 3 H), 2.45 (s, 3 H). 13C NMR (75MHz, CDCl3):
δ = 6.99-7.57 (m, 8
δ
= 159.10, 140.83, 138.30, 133.91,
128.67, 128.18, 127.58, 127.45, 123.88, 114.17, 55.34, 21.56.
3-Methyl-2'-methoxy-biphenyl: Colorless oil. 1H NMR (300 MHz, CDCl3):
H), 3.84 (s, 3 H), 2.44 (s, 3 H). 13C NMR (75MHz, CDCl3):
δ
= 7.00-7.36 (m, 8
δ
= 156.46, 139.50, 138.49, 137.52,
130.91, 130.24, 128.52, 127.87, 127.73, 126.68, 120.76, 111.13, 55.54, 21.57.
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1-[4-(3-methylphenyl)phenyl]-1-ethanone: 1H NMR (300 MHz, CDCl3):
δ =2.45 (s, 3 H), 2.65
13
(s, 3 H), 7.22-8.04 (m, 8 H). C NMR (75 MHz, CDCl3):
δ
= 197.82, 145.94, 139.85, 138.60,
135.86, 128.98, 128.86, 128.02, 127.22, 124.38, 26.66, 21.52.
1
1-Nitro-3-phenylbenzene: H NMR (300 MHz, CDCl3):
δ
= 7.25-8.44 (m, 9 H). 13C NMR (75
MHz, CDCl3):
121.94.
δ
= 148.71, 142.85, 138.65, 133.03, 129.69, 129.15, 128.52, 127.14, 122.01,
1
3-Phenylbenzaldehyde: H NMR (300 MHz, CDCl3):
δ
= 7.26-8.12 (m, 9 H), 10.10 (s, 1 H).
13C NMR (75 MHz, CDCl3):
128.64, 128.20, 128.02, 127.14.
δ = 192.38, 142.16, 136.91, 135.57, 133.07, 129.50, 129.01,
2-Phenylbenzaldehyde: 1H NMR (300 MHz, CDCl3):
δ
= 6.87-8.01 (m, 9 H), 9.97 (s, 1 H). 13C
NMR (75 MHz, CDCl3):
128.10, 127.75, 127.53.
δ = 192.44, 145.92, 137.70, 133.56, 130.75, 130.07, 129.51, 128.40,
Conclusion
In conclusion, synthesis of imidazolium-based ionic liquid was successfully achieved on the
surface of SBA-15. And partial conversion of imidazolium moieties to carbene-Pd generated an
efficient catalytic heterogeneous system containing supported NHC-Pd and ionic liquid.
Addition of Cs2CO3 increased the product yield and decreased the amount of Pd mol% by
synergic effect with TBAF in Hiyama coupling reaction. Under the optimized conditions, NHC-
Pd/SBA-15/IL had chemoselectivity towards Hiyama products could successfully be run for six
set-up with 5th successful recycling.
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Reference
[1] B. Karimi, F.B. Rostami, M. Khorasani, D. Elhamifar, H. Vali, Selective oxidation of
alcohols with hydrogen peroxide catalyzed by tungstate ions (WO4=) supported on periodic
mesoporous organosilica with imidazolium frameworks (PMO-IL), Tetrahedron, 70 (2014)
6114-6119.
[2] B. Karimi, D. Enders, New N-Heterocyclic Carbene Palladium Complex/Ionic Liquid Matrix
Immobilized on Silica: Application as Recoverable Catalyst for the Heck Reaction, Org. Lett. 8
(2006) 1237.
[3] B. Karimi, D. Elhamifar, J.H. Clark, A.J. Hunt, Ordered Mesoporous Organosilica with
Ionic-Liquid Framework: An Efficient and Reusable Support for the Palladium-Catalyzed
Suzuki-Miyaura Coupling Reaction in Water, Chemistry – A European Journal, 16 (2010) 8047-
8053.
[4] B. Karimi, A. Zamani, SBA-15-functionalized palladium complex partially confined with
ionic liquid: an efficient and reusable catalyst system for aqueous-phase Suzuki reaction,
Organic & Biomolecular Chemistry, 10 (2012) 4531-4536.
[5] H.Yang, X. Han, G. Li, Y. Wang. N-Heterocyclic carbene palladium complex supported on
ionic liquid-modified SBA-16: an efficient and highly recyclable catalyst for the Suzuki and
Heck reactions, Green Chem., 11 (2009) 1184-1193.
[6] S. Zhang, Y. Zhang, Y. Wang, S. Liu, Y. Deng, Sonochemical formation of iron oxide
nanoparticles in ionic liquids for magnetic liquid marble, Physical Chemistry Chemical Physics,
14 (2012) 5132-5138.
15

ACCEPTED MANUSCRIPT
[7] E. Vanecht, K. Binnemans, S. Patskovsky, M. Meunier, J.W. Seo, L. Stappers, J. Fransaer,
Stability of sputter-deposited gold nanoparticles in imidazolium ionic liquids, Physical
Chemistry Chemical Physics, 14 (2012) 5662-5671.
[8] G. Liu, M. Hou, T. Wu, T. Jiang, H. Fan, G. Yang, B. Han, Pd(ii) immobilized on
mesoporous silica by N-heterocyclic carbene ionic liquids and catalysis for hydrogenation,
Physical Chemistry Chemical Physics, 13 (2011) 2062-2068.
[9] Y.S. Chun, J.Y. Shin, C.E. Song, S.-g. Lee, Palladium nanoparticles supported onto ionic
carbon nanotubes as robust recyclable catalysts in an ionic liquid, Chemical Communications,
(2008) 942-944.
[10] F. Rajabi, W.R. Thiel, An Efficient Palladium N-Heterocyclic Carbene Catalyst Allowing
the Suzuki–Miyaura Cross-Coupling of Aryl Chlorides and Arylboronic Acids at Room
Temperature in Aqueous Solution, Advanced Synthesis & Catalysis, 356 (2014) 1873-1877.
[11] T. Hiyama, How I came across the silicon-based cross-coupling reaction, Journal of
Organometallic Chemistry, 653 (2002) 58-61.
[12] Y. Hatanaka, T. Hiyama, Cross-coupling of organosilanes with organic halides mediated by
a palladium catalyst and tris(diethylamino)sulfonium difluorotrimethylsilicate, The Journal of
Organic Chemistry, 53 (1988) 918-920.
[13] Y. Hatanaka, T. Hiyama, Highly Selective Cross-Coupling Reactions of Organosilicon
Compounds Mediated by Fluoride Ion and a Palladium Catalyst, Synlett, 1991 (1991) 845-853.
[14] J.-Y. Lee, G.C. Fu, Room-Temperature Hiyama Cross-Couplings of Arylsilanes with Alkyl
Bromides and Iodides, Journal of the American Chemical Society, 125 (2003) 5616-5617.
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ACCEPTED MANUSCRIPT
[15] J.-H. Li, C.-L. Deng, W.-J. Liu, Y.-X. Xie, Pd(OAc)2/DABCO as an Inexpensive and
Efficient Catalytic System for Hiyama- Cross-Coupling Reactions of Aryl Halides with
Aryltrimethoxysilanes, Synthesis, 2005 (2005) 3039-3044.
[16] R. Lerebours, C. Wolf, Palladium-Phosphinous Acid Catalyzed Cross-Coupling of Aryl
Halides Using a Hypervalent Phenylsilane in Water, Synthesis, 2005 (2005) 2287-2292.
[17] T. Huang, C.-J. Li, Palladium-catalyzed coupling of aryl halides with arylhalosilanes in air
and water, Tetrahedron Letters, 43 (2002) 403-405.
[18] Á. Gordillo, E. de Jesús, C. López-Mardomingo, C−C Coupling Reactions of Aryl
Bromides and Arylsiloxanes in Water Catalyzed by Palladium Complexes of Phosphanes
Modified with Crown Ethers, Organic Letters, 8 (2006) 3517-3520.
[19] H.F. Sore, W.R.J.D. Galloway, D.R. Spring, Palladium-catalysed cross-coupling of
organosilicon reagents, Chemical Society Reviews, 41 (2012) 1845-1866.
[20] M. Guo, L. Qi, Q. Zhang, Z. Zhu, W. Li, X. Li, MIDA as a simple and highly efficient
ligand for palladium-catalyzed Hiyama cross-coupling of aryl halides, Organic & Biomolecular
Chemistry, 12 (2014) 7136-7139.
[21] A. Modak, J. Mondal, A. Bhaumik, Pd-grafted periodic mesoporous organosilica: an
efficient heterogeneous catalyst for Hiyama and Sonogashira couplings, and cyanation reactions,
Green Chemistry, 14 (2012) 2840-2855.
[22] E. Hagiwara, K.-i. Gouda, Y. Hatanaka, T. Hiyama, NaOH-Promoted cross-coupling
reactions of organosilicon compounds with organic halides: Practical routes to biaryls,
alkenylarenes and conjugated dienes, Tetrahedron Letters, 38 (1997) 439-442.
[23] S. Rostamnia, E. Doustkhah, Nanoporous silica-supported organocatalyst: a heterogeneous
and green hybrid catalyst for organic transformations, RSC Advances, 4 (2014) 28238-28248.
17

ACCEPTED MANUSCRIPT
[24] S. Rostamnia, A. Morsali, Size-controlled crystalline basic nanoporous coordination
polymers of Zn4O(H2N-TA)3: Catalytically study of IRMOF-3 as a suitable and green catalyst
for selective synthesis of tetrahydro-chromenes, Inorganica Chimica Acta, 411 (2014) 113-118.
[25] S. Rostamnia, H. Xin, Simultaneous application of ultrasonic irradiation and immobilized
ionic liquid onto the SBA-15 nanoreactor (US/[MPIm]Cl@SBA-15): A robust, recyclable, and
useful combined catalytic system for selective and waste-free Kabachnik Fields reaction, Journal
of Molecular Liquids, 195 (2014) 30-34.
[26] S. Rostamnia, X. Liu, D. Zheng, Ordered interface mesoporous immobilized Pd pre-
catalyst: En/Pd complexes embedded inside the SBA-15 as an active, reusable and selective
phosphine-free hybrid catalyst for the water medium Heck coupling process, Journal of Colloid
and Interface Science, 432 (2014) 86-91.
[27] S. Rostamnia, E. Doustkhah, A. Nuri, Hexafluoroisopropanol dispersed into the nanoporous
SBA-15 (HFIP/SBA-15) as a rapid, metal-free, highly reusable and suitable combined catalyst
for domino cyclization process in chemoselective preparation of alkyl rhodanines, Journal of
Fluorine Chemistry, 153 (2013) 1-6.
[28] S. Rostamnia, E. Doustkhah, A mesoporous silica/fluorinated alcohol adduct: an efficient
metal-free, three-component synthesis of indazolophthalazinetrione heterocycles using a reusable
nanoporous/trifluoroethanol adduct (SBA-15/TFE), Tetrahedron Letters, 55 (2014) 2508-2512.
[29] S. Rostamnia, A. Hassankhani, H.G. Hossieni, B. Gholipour, H. Xin, Brønsted acidic
hydrogensulfate ionic liquid immobilized SBA-15: [MPIm][HSO4]@SBA-15 as an
environmentally friendly, metal- and halogen-free recyclable catalyst for Knoevenagel–Michael-
cyclization processes, Journal of Molecular Catalysis A: Chemical, 395 (2014) 463-469.
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[30] S. Shi, Y. Zhang, Pd(OAc)2-Catalyzed Fluoride-Free Cross-Coupling Reactions of
Arylsiloxanes with Aryl Bromides in Aqueous Medium, The Journal of Organic Chemistry, 72
(2007) 5927-5930.
[31] J. Yang, L. Wang, Synthesis and characterization of dinuclear NHC-palladium complexes
and their applications in the Hiyama reactions of aryltrialkyoxysilanes with aryl chlorides,
Dalton Transactions, 41 (2012) 12031-12037.
[32] S.E. Denmark, C.S. Regens, Palladium-Catalyzed Cross-Coupling Reactions of
Organosilanols and Their Salts: Practical Alternatives to Boron- and Tin-Based Methods,
Accounts of Chemical Research, 41 (2008) 1486-1499.
[33] L. Bi, G.I. Georg, Direct Hiyama Cross-Coupling of Enaminones With
Triethoxy(aryl)silanes and Dimethylphenylsilanol, Organic Letters, 13 (2011) 5413-5415.
[34] B. Tian, X. Liu, B. Tu, C. Yu, J. Fan, L. Wang, S. Xie, G.D. Stucky, D. Zhao, Self-adjusted
synthesis of ordered stable mesoporous minerals by acid-base pairs, Nat Mater, 2 (2003) 159-
163.
[35] H. Qiu, S.M. Sarkar, D.-H. Lee, M.-J. Jin, Highly effective silica gel-supported N-
heterocyclic carbene-Pd catalyst for Suzuki-Miyaura coupling reaction, Green Chemistry, 10
(2008) 37-40.
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Research highlights
► SBA-15/IL were applied as a support for Pd in Hiyama reaction of various aryl halides and
triethoxyphenylsilane. ► NHC-Pd/SBA-15/IL was synthesized. ►A reusable porous catalyst system
using commercially available material was employed. ►Represents advantages, operational simplicity,
no waste, higher yield and with easy workup.