Pd(0) complex of fuberidazole modified magnetic nanoparticles: A novel magnetically retrievable high-performance catalyst for Suzuki and Stille C-C coupling reactions

Article abstract of DOI:10.1002/aoc.5771

Fuberidazole has been successfully immobilized onto nano-Fe₃O₄ supported (3-chloropropyl)trimethoxysilane (3-CPTS) leading to a novel functionalized magnetic nanoparticle (FB/MNP). The Pd(0) complex, Pd-FB/MNP, was prepared by grafting Pd (OAc)₂ on FB/MNP and subsequent reduction of a synthesized Pd (II) complex using NaBH₄. Pd-FB/MNP has been characterized by FT-IR, SEM, TGA, XRD, ICP, EDS, BET and VSM. The Pd(0) complex proved to be an efficient phosphine- and halide-free recyclable heterogeneous catalyst for Suzuki as well as for Stille C-C coupling reactions showing high catalytic activity (up to 98percent). Its catalytic activity in both reactions has been studied in PEG-400 as a green solvent. Besides, the selectivity of aryl iodide and aryl bromide over aryl chloride is observed during the C-C coupling reaction. The catalyst could be recovered easily from the reaction mixture using an external magnet device and recycled several times without considerable loss in activity. Additionally, the results of a palladium leaching test of the nano-catalyst demonstrate that no leaching of Pd took place during the C-C coupling process making the procedure environmentally friendly.

Full text of DOI:10.1002/aoc.5771

Received: 17 December 2019
DOI: 10.1002/aoc.5771
Revised: 19 March 2020
Accepted: 12 April 2020
F U L L P A P E R
Pd(0) complex of fuberidazole modified magnetic
nanoparticles: A novel magnetically retrievable high-
performance catalyst for Suzuki and Stille C-C coupling
reactions
Kheirollah Nouri | Mitra Ghassemzadeh
Maryam Afsharpour
| Farshid Mohsenzadeh |
Department of Inorganic Chemistry,
Fuberidazole has been successfully immobilized onto nano-Fe3O4 supported
(3-chloropropyl)trimethoxysilane (3-CPTS) leading to a novel functionalized
magnetic nanoparticle (FB/MNP). The Pd(0) complex, Pd-FB/MNP, was pre-
pared by grafting Pd (OAc)2 on FB/MNP and subsequent reduction of a syn-
thesized Pd (II) complex using NaBH4. Pd-FB/MNP has been characterized
by FT-IR, SEM, TGA, XRD, ICP, EDS, BET and VSM. The Pd(0) complex
proved to be an efficient phosphine- and halide-free recyclable heteroge-
neous catalyst for Suzuki as well as for Stille C-C coupling reactions show-
ing high catalytic activity (up to 98%). Its catalytic activity in both reactions
has been studied in PEG-400 as a green solvent. Besides, the selectivity of
aryl iodide and aryl bromide over aryl chloride is observed during the C-C
coupling reaction. The catalyst could be recovered easily from the reaction
mixture using an external magnet device and recycled several times without
considerable loss in activity. Additionally, the results of a palladium leaching
test of the nano-catalyst demonstrate that no leaching of Pd took place dur-
ing the C-C coupling process making the procedure environmentally
friendly.
Chemistry & Chemical Engineering
Research Center of Iran, Pajoohesh Blvd.,
17th Km of Tehran–Karaj Highway,
Tehran, 14968-13151, Iran
Correspondence
Mitra Ghassemzadeh, Department of
Inorganic Chemistry, Chemistry &
Chemical Engineering Research Center of
Iran, Pajoohesh Blvd., 17th Km of
Tehran–Karaj Highway, Tehran
14968-13151, Iran.
Email: mghassemzadeh@ccerci.ac.ir
K E Y W O R D S
carbon–carbon coupling reactions, magnetic nanoparticle, Pd(0) complex of fuberidazole, Stille
reaction, Suzuki reaction
1 | INTRODUCTION
heterogeneous catalysts.[9] In general, nanoparticles pos-
In the past few decades, the design, synthesis, and develop-
ment of heterogeneous reusable catalysts have attracted
considerable attention in organic chemistry.[1–3] In order
to reach this important goal, the homogeneous active sites
of catalysts has already been immobilized on various
supports.[4–8] Recently, magnetic nanoparticles have been
employed as convenient supports for the preparation of
sess several attractive features such as high stability, high
specific surface area, non-toxicity, ease of surface modifica-
tion and tunable particle sizes.[10,11] The main advantage
of magnetic nanoparticles over other high surface area
supports, remains in their facile recovery and recyclability
from the reaction mixture; since no conventional filtration
or purification is required.[12–14] In other words, the use of
Appl Organomet Chem. 2020;e5771.
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© 2020 John Wiley & Sons, Ltd.
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a simple external magnetic field along with minimal
workup procedures leads to a greener protocol from an
academic and industrial vantage point.[15]
a novel Pd(0) complex supported on functionalized Fe3O4
nanoparticles. In addition, the viability of this material as
a recyclable heterogeneous catalyst is studied for the syn-
thesis of biphenyl derivatives under Suzuki and Stille C-C
coupling reaction conditions.
Carbon–carbon coupling reactions have attracted a
great deal of attention in the preparation of natural
products, agrochemicals and pharmaceuticals[16] such
as Atazanavir,[17] Vancomycin[18] and MK2 inhibi-
tors.[19] Suzuki and Stille Pd-catalyzed cross-coupling
reactions represent two powerful and most widely used
methods in organic chemistry for the formation of C-C
bonds. In the classical method, these reactions have
been catalyzed by Pd-based Lewis acids and complexes
containing phosphine- and chlorine-based ligands hav-
ing air and/or moisture-sensitive properties with high
toxicity. Besides, the main problem encountered with
these homogeneous catalysts remains in Pd catalyst
recovery and metal ion leaching triggering undesired
metal contamination of the products.[20] To minimize
and overcome these issues, the design of Pd-based catalysts
via heterogenization has become a necessity.[21,22] In this
regard, various palladium-immobilized materials have
been designed to achieve waste-free processes.[23]
2 | EXPERIMENTAL SECTION
2.1 | Materials and methods
All chemicals were purchased from Merck, Aldrich or
Fluka and used without further purification. Fe3O4
nanoparticles, (3-chloropropyl)trimethoxysilane (3-CPTS)
modified Fe3O4 nanoparticles (3-CPTS/Fe3O4) and
fuberidazole (FB) have been prepared according to
literature.[48–50]
Powder X-ray Diffraction (XRD) of the catalyst was
performed on a PW 1730 instrument from PHILIPS
ꢀ
Company with Cu Kα-radiation froꢀm 2θ = 5 to 80 at
40 kV and 30 mA (scan step: 0.04 /sec). Fourier trans-
form infrared (FT-IR) spectra were recorded on a
VRTEX 70 model Bruker FT-IR spectrometer using KBr
Pellets (4000–400 cm−1). Energy-dispersive X-ray spec-
troscopy (EDS) and scanning electron microscopy
(SEM) were carried out on a FEI Quanta 200 scanning
electron microscopy (using an accelerating voltage of
25 kV). Thermogravimetric analyses (TGA) of the com-
pounds were carried out on a Perkin Elmer Pyris Dia-
mond Thermogravimetric Analyzer (temperature range:
30–800 ꢀC, heating rate: 10 ꢀC/min). Melting points
were determined using the Griffin melting point appa-
ratus and are uncorrected. The vibrating sample magne-
tometer (VSM) measurements were performed using a
MDKFD vibrating-sample magnetometer (by an exter-
nal field of up to 8 kOe). The Pd content of the com-
pound was determined by inductively coupled plasma
optical emission spectrometry (ICP-OES; PerkinElmer
optima 8000).
Benzimidazoles are therapeutically active building
blocks, which have been extensively investigated in the
field of the pharmaceutical industry and drug design.[24]
Their coordination behavior towards transition metal
ions have different pharmacological and biological appli-
cations.[25] Moreover, their derivatives incorporating a
fluorescent aromatic moiety, usually act as chelating sites
toward metal ions and are generally utilized as chemical
tools for the recognition of metal ions.[26,27] So far, a
range of 2-aryl substituted benzimidazole-based moieties
(in order to chelate to transition metal ions) have been
used as a receptor for fluorescent sensing, e.g. 2-(20-
hydroxyphenyl)-benzimidazole,[28–31] 2-(20-aminophenyl)
-benzimidazole,[32–35] 2-(5-R-1H-benzimidazol-2-yl)-ben-
zene-1,4-diols.[36,37]
Fuberidazole (2-(20-furyl)-1H-benzimidazole) is
a
well-known antifungal agrochemical. It is essentially
used for the treatment of seeds particularly against Fusar-
ium spp as an agricultural plant pathogen.[38–40] The
structure of fuberidazole contains two aromatic heterocy-
cles: a 2-substituted benzimidazole moiety and a 2-furyl
one. While this biheterocyclic compound has the poten-
tial to coordinate to metal ions, a survey in the literature
revealed that there is no report on Pd complexes con-
taining fuberidazole as a chelating agent.
2.2 | Preparation of the catalyst
2.2.1 | Preparation of FB/MNP
Taking into account the importance of magnetic
nanoparticles as a sustainable support for chemical
transformations[41–43] and our interest in the design of
novel Pd-complexes[44–47] together with the use of
fuberidazole as a new benzimidazole-based ligand, herein,
we wish to report the preparation and characterization of
Fuberidazole (FB, 2 mmol) was added to a suspension of
3-CPTS/Fe3O4 (1 g) in toluene (50 ml) and stirred for
32 hr at 80 C under N2 atmosphere. The resulting resi-
due was separated by magnetic decantation, washed with
ethanol (3 × 10 ml) and air dried at room temperature to
give functionalized FB/MNP.
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2.2.2 | One-pot preparation of Pd-
FB/MNP
reaction mixture using an external magnetic bar and was
air-dried before being used in the next cycle. The reaction
mixture was extracted with diethyl ether (15 ml). The
organic layer was washed with water and dried over
anhydrous sodium sulfate. The solvent was then evapo-
rated to afford pure products.
Palladium acetate (0.25 g, 1.1 mmol) was added to a sus-
pension of FB/MNP (0.5 g) in ethanol (25 ml) and stirred
for 20 hr under reflux conditions. NaBH4 (0.19 g,
0.5 mmol) was added to the reaction mixture and
refluxed for further 2 hr. The resulting residue was sepa-
rated by a magnetic decantation method using an exter-
nal magnetic bar, washed with ethanol (3 × 10 ml) and
allowed to dry at room temperature.
2.3.2 | Experimental procedure for the
Stille reaction
The same procedure as in the Suzuki reaction was carried
out using triphenyltin chloride (0.5 mmol) instead of
phenylboronic acid.
2.3 | General procedure for the catalytic
reactions
2.3.1 | Experimental procedure for the
3 | RESULTS AND DISCUSSION
Suzuki reaction
3-CPTS/Fe3O4 was prepared from the reaction of Fe3O4
nanoparticles with 3-CPTS and was used as a support for
the preparation of fuberidazole functionalized magnetic
nanoparticles (FB/MNP). Eventually, the reaction of pal-
ladium (II) acetate with FB/MNP followed by the reduction
lof Pd (II) moieties using NaBH4 in EtOH by a one-pot two-
step reaction gave Pd-FB/MNP (Scheme 1).
In a round bottom flask (25 ml), a mixture of phe-
nylboronic acid (1 mmol), aryl halide (1 mmol), sodium
carbonate (3 mmol), Pd-FB/MNP (15 mg), and PEG-400
ꢀ
(1 ml) was stirred at 80 C for an appropriate reaction
time. After completion of the reaction (monitored by
TLC using n-hexane/acetone (8:2) as eluent), the reaction
mixture was diluted with water (15 ml) and diethyl ether
(2 ml). The heterogeneous catalyst was removed from the
The synthesized Pd-FB/MNP is an air-stable solid. It
was characterized by powder X-ray diffraction (XRD),
SCHEME 1 Route to the preparation of Pd-FB/MNP

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scanning electron microscopy (SEM), energy-dispersive X-
ray spectroscopy (EDS), inductively coupled plasma (ICP),
thermogravimetric analysis (TGA), Fourier transform infra-
red spectroscopy (FT-IR), nitrogen adsorption–desorption
isotherms and vibrating sample magnetometer (VSM).
agreement with Fe3O4 standard data (JCPDS-No.
85–1436). The same template has also been observed in
the XRD pattern of 3-CPTS/Fe3O4, FB/MNP and Pd-
FB/MNP confirming the intactness of Fe3O4 nanostruc-
ture after modification. The XRD pattern ofꢀPd-FB/MNꢀP
ꢀ
showed the reflections at 2θ = 39.2 , 46.3 and 67.5 ,
ascribed to the reflections of the (111), (200) and (220)
diffraction planes for the Pd(0) phase (JCPDS-No.
46–1043). These three new absorptions confirm that pal-
ladium exists solely in the form of Pd(0), not Pd (II).
The SEM images revealed that Pd-FB/MNP has a
quasi-spherical morphology with a very homogeneous
particle size distribution. This novel material has an aver-
age diameter of 17 nm (Figure 2).
3.1 | Characterization of Pd-FB/MNP
The XRD patterns of Fe3O4 nanoparticles, 3-CPTS/Fe3O4,
FB/MNP and Pd-FB/MNP are shown in Figure 1. The
XRD pattern of Fe3O4 showed peaks at 2ꢀθ values of 30.9
ꢀ
ꢀ
ꢀ
ꢀ
ꢀ, 35.5 , 44.2 , 53.7 , 57.8 and 62.4 related to the
crystal planes in Fe3O4 cubic lattice, which were in
FIGURE 1 The powder XRD
patterns of Fe3O4 nanoparticles,
3-CPTS/Fe3O4, FB/MNP and Pd-
FB/MNP
FIGURE 2 SEM images of Pd-FB/MNP

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The EDS analysis carried out on Pd-FB/MNP con-
firmed also the presence of Fe, O, Si, C, N, and Pd with
the weight percentage of 38.53, 25.89, 0.57, 10.68, 2.25,
and 22.08, respectively (Figure 3). These results indicate
that Pd has been anchored to FB/MNP. The exact
amount of palladium in Pd-FB/MNP was found to be
1.84 × 10−3 mol g−1 based on the results obtained from
inductively coupled plasma optical emission spectrome-
try (ICP-OES).
Functionalization of the Fe3O4 nanoparticles with
organic layers was also verified by the FT-IR technique.
According to the FT-IR spectra of Fe3O4 nanoparticles,
3-CPTS/Fe3O4, FB/MNP and Pd-FB/MNP (Figure 4), the
stretching vibrations of Fe-O moieties were observed by a
strong absorption at ca 580 cm−1
.
Symmetrical- and asymmetrical modes of the surface
OH groups were observed at 3420–3550 cm−1 in FT-IR
spectrum of all compounds (Figure 4a). Modification of
Fe3O4 nanoparticles with 3-CPTS was confirmed by
absorption at 2947 cm−1 and 1087 cm−1, which are
related to C-H– and Si-O stretching vibration, respec-
tively. The vibration bands in FT-IR spectrum of
FB/MNP observed at 1404–1440 cm−1 and 1628 cm−1
could be assigned to C-N–, C=C– and C=N stretching
vibrations, respectively, confirming the successful synthe-
sis of FB/MNP.[49]
Thermogravimetric analysis (TGA) has been used to
determine the thermal degradation behavior of synthe-
sized compounds. The thermal analysis has been per-
formed on all samples by heaꢀting the compounds in the
temperature range of 25–800 C in air. The TGA curves
of the compounds show the mass loss of the supported
functional groups upon increasing the temperature. The
TGA curve of all compounds (Figure 5) shows a small
weight loss (ca. 5%) at temperatures below 200 ꢀC, which
can be assigned to the dehydration of the surface OH
FIGURE 4 FT-IR spectra of (a) Fe3O4 nanoparticles,
(b) 3-CPTS/Fe3O4, (c) FB/MNP and (d) Pd-FB/MNP
groups and removal of the physically adsorbed solvent in
these compounds. In the TGA curve of Fe3O4, the small
ꢀ
weight loss in higher temperature (>300 C) corresponds
to the thermal crystal phase transformꢀation of Fe3O4. The
weight loss in the range of 200–800 C observed in the
TGA curves of 3-CPTS/Fe3O4, FB/MNP and Pd-FB/MNP
is 13%, 17% and 19%, respectively and might be related to
the decomposition and removal of organic functional
groups on Fe3O4 surface.
The vibrating sample magnetometer (VSM) of Fe3O4
nanoparticles and Pd-FB/MNP were conducted at room
temperature. According to the VSM diagrams (Figure 6),
these compounds have neither remanence nor coercivity
and exhibit superparamagnetic characteristics at room
temperature. Pd-FB/MNP (60.05 emu g−1) exhibit lower
magnetic value compared to Fe3O4 nanoparticles
(99.7 emu g−1), which may be explained as a conse-
quence of functionalization of Fe3O4 nanoparticles with
non-magnetic materials like palladium complex.
In general, the specific BET surface area of the catalyst
plays a crucial role in the enhancement of heterogeneously
catalyzed organic reactions. In this regard, nitrogen
FIGURE 3 EDS analysis of Pd-FB/MNP

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FIGURE 5 TGA curves of Fe3O4
nanoparticles, 3-CPTS/Fe3O4, FB/MNP and Pd-
FB/MNP
FIGURE 6 Magnetization hysteresis loops
of Fe3O4 nanoparticles and Pd-FB/MNP
adsorption/desorption isotherms were used to determine
the surface area of Pd-FB/MNP. N2 adsorption/desorption
measurements demonstrate the type IV isotherm with H3
hysteresis loop illustrating the presence of mesopores
(Figure 7). The specific surface area of Pd-FB/MNP was cal-
culated to be 38.45 m2/g using Brunauer–Emmett–Teller
(BET) method. On the other hand, the surface area of
Fe3O4 nanoparticles is reported to be 57.54 m2/g.[51] Appar-
ently, the surface area of Pd-FB/MNP was significantly
decreased via Fe3O4 functionalization indicating the stabili-
zation of organic layers including palladium complex on the
surface of Fe3O4 nanoparticles.
To evaluate the efficiency of Pd-FB/MNP, the cou-
pling of iodobenzene (1 mmol) and phenylboronic acid
(1 mmol) was studied as a model reaction. In order to
3.2 | Catalytic activity of Pd-FB/MNP in
Suzuki and Stille reactions
The catalytic activity of Pd-FB/MNP has been investi-
gated in Suzuki and Stille carbon–carbon coupling
reactions.
FIGURE 7 N2 adsorption–desorption isotherm of Pd-FB/MNP

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determine the optimum reaction conditions, the reaction
temperature, the amount of catalyst and the effect of sol-
vent and base were investigated and the results based on
product yield are summarized in Table 1.
catalyst, faster completion of the reaction was observed
(40 min). The optimum amount of Pd-FB/MNP was
found to be 15 mg of catalyst containing 0.0276 mmol
of Pd per one mmol of substrate (phenylboronic acid)
(Table 1, entry 6) leading to a quantitative yield of
biphenyl.
The same reaction was carried out in the presence of
various solvents such as H2O, DMF, DMSO and PEG-400
(Table 1, entries 8–11). The excellent yield of product
(98%) was obtained using DMF, DMSO, and PEG-400 in
40 min. Due to the toxicity of DMF and DMSO in com-
parison to PEG-400 (known as a green solvent), the use
of the formers is not recommended. Therefore, PEG-400
was chosen as the optimum solvent.
Finally, the synthesis of biphenyl was also performed
in the presence of common bases such as NaOEt, NaOH,
Et3N, and Na2CO3 (Table 1, entries 12–15). Among these
bases, Na2CO3 proved to be the most effective one on
the basis of shorter reaction time (40 min) and excellent
yield (98%).
In an initial study, the reaction temperatureꢀ was
optimized within a temperature range of 25 to 80 C in
the presence of 15 mg of catalyst, Na2CO3 as base and
PEG-400 as solvent (Table 1, entries 1–3). While the
poor yield of product was observed up to 60 ꢀC, the reac-
ꢀ
tion yield sharply increased at 80 C leading to excellent
yield (98%).
The model reaction was studied in the absence and
presence of the catalyst (Table 1, entries 4 and 5). No
product was obtained in the absence of the catalyst
even after long reaction time (24 hr), whereas the use
of 10 mg of catalyst led to the formation of product
after 70 min in high yield (90%). The effect of the
amount of catalyst was determined from three reactions
containing 10, 15 and 20 mg of Pd-FB/MNP (Table 1,
entries 5–7). In the presence of 15 and 20 mg of
TABLE 1
Optimization of Suzuki coupling reaction in the presence of Pd-FB/MNPa
Entry
Catalyst (mg)
Solvent
Base
Temperature (ꢀC)
Time (min)
Yield (%)b
Temperature effect
1
15
15
15
PEG-400
PEG-400
PEG-400
Na2CO3
Na2CO3
Na2CO3
r.t.
60
80
60
60
40
Trace
31
2
3
98
Catalyst amount
4
-
PEG-400
PEG-400
PEG-400
PEG-400
Na2CO3
Na2CO3
Na2CO3
Na2CO3
80
80
80
80
24 h
70
-
5
10
15
20
90
98
98
6
40
7
40
Solvent effect
8
15
15
15
15
H2O
Na2CO3
Na2CO3
Na2CO3
Na2CO3
80
80
80
80
70
40
40
40
63
98
98
98
9
DMF
10
DMSO
PEG-400
11
Base effect
12
13
14
15
15
15
15
15
PEG-400
PEG-400
PEG-400
PEG-400
NaOEt
NaOH
Et3N
80
80
80
80
60
60
60
40
Trace
53
49
Na2CO3
98
aReaction conditions: iodobenzene (1 mmol), phenylboronic acid (1 mmol), base (3 mmol) and solvent (1 ml),
bIsolated yield.

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Accordingly, the reactꢀion containing Pd-FB/MNP
be an important advantage of the presented method since
selectivity is an important factor in catalytic systems.
To extend the scope of activity of the catalyst, it was
also tested for Stille C-C coupling of a variety of aryl
halides with triphenyltin chloride (Ph3SnCl) in a molar
ratio of 1:0.5 under optimized reaction conditions. As
depicted in Table 3, the biphenyl derivatives were
obtained in high to excellent yields and TON values for
aryl halides containing either electron-rich or electron-
deficient substituents. The high value of TON confirms
the excellent catalytic activity of Pd-FB/MNP in coupling
reactions. While the same trend is observed for Stille and
Suzuki coupling reaction, Stille reaction requires a longer
reaction time. Interestingly, this reaction showed also the
same selectivity towards chloro substituted aryl bromide
(Table 3, entry 7).
Reusability of the catalysts is an important factor in
the field of heterogeneous catalysis. To investigate this
issue, the recyclability of Pd-FB/MNP catalyst has been
studied in the coupling reaction of iodobenzene with
phenylboronic acid as a model reaction. After comple-
tion of the reaction, the catalyst was removed readily
from the reaction mixture using an external magnetic
bar, washed with diethyl ether, and reused for a subse-
quent run. As depicted in Figure 8, Pd-FB/MNP can be
reused up to eight times without significant loss in cata-
lytic activity (product yield: 98% for the first run; 90% for
the eighth run).
(15 mg) as a catalyst at 80 C after 40 min exhibited the
highest isolated yield and afforded the product (biphenyl)
quantitatively (Table 1, entry 3).
After obtaining the best reaction conditions, a variety
of aryl halides bearing electron-donating (hydroxyl, met-
hoxy, and methyl) and electron-withdrawing (chloro,
cyano, carbonyl, and nitro) substituents were investigated
to confirm the generality of the present method. As
depicted in Table 2, all biphenyl products were obtained
in high to excellent yields and TON values, although the
reaction time depended strongly on the nature of substit-
uents. The results revealed that this methodology is effec-
tive for phenyl iodide (Table 2, entry 1) and -bromide
(Table 2, entry 4). On the contrary, phenyl chloride
(Table 2, entry 13) showed no reactivity towards the cou-
pling reaction. In this regard, we found that the chloro
functional group remained intact during the C-C cou-
pling reactions (Table 2, entry 10). This limitation might
To confirm the sustainable nature of Pd-FB/MNP, the
leaching test was performed for the optimized Suzuki
coupling model reaction (Table 2, entry 1). For this pur-
pose, two parallel reactions were carried out. In the first
reaction, 60% of biphenyl product was obtained in half-
time of reaction (20 min), whereas in the second reaction,
catalyst was removed after 20 min and the reaction was
FIGURE 8 Recyclability of Pd-FB/MNP in the coupling
reaction of iodobenzene with PhB (OH)2
TABLE 4
A comparison study of Pd-FB/MNP in the Suzuki coupling reaction of iodobenzene with phenylboronic acid with previously
reported catalysts
Time
(min)
Yield (%)
[Ref.]
Entry Catalyst
Reaction conditions
1
PANI-Pd
K2CO3, 1,4-dioxane: H2O (1:1),
95 ꢀC
240
9153
9754
2
N,N0-bis(2-pyridinecarboxamide)-1,2-benzene Pd
complex
H2O, K2CO3, 100 ꢀC
180
3
NHC-Pd (II) complex
Au/Pd NPs
THF, Cs2CO3, 80 ꢀC
12 h
24 h
12 h
300
90
8855
8856
9557
9958
9759
9960
98[this work]
4
EtOH/H2O, K2CO3, 80 ꢀC
H2O, KOH, 100 ꢀC
5
Pd NP
7
Polymer anchored Pd (II) Schiff base complex
Pd/SBA-15/IL DABCO
SBA-16-2 N-Pd (II)
Pd-FB/MNP
K2CO3, DMF: H2O (1:1), 80 ꢀC
K2CO3, H2O, 80 ꢀC
8
9
EtOH, K2CO3, 60 ꢀC
120
40
10
PEG-400, Na2CO3, 80 ꢀC

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then allowed to continue without catalyst. In this stage,
63% of biphenyl product (instead of 98%) was obtained.
These experiments confirm that the leaching of palla-
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The results obtained from Suzuki coupling reaction of
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4 | CONCLUSIONS
Pd-FB/MNP has been introduced as a novel magneti-
cally retrievable nanoparticle material. Its formation has
been confirmed by spectroscopic techniques such as FT-
IR, SEM, TGA, XRD, ICP, EDS, BET and VSM. The
viability of Pd-FB/MNP as a catalyst has been investi-
gated for Suzuki and Stille C-C coupling reactions in a
mild basic green media (Na2CO3 in PEG-400). Also,
selective formation of biphenyl derivatives from aryl
iodides and bromides was successfully achieved. The
attractive features of this phosphine- and halide-free
protocol remain in its relatively low palladium loading
(2.76 mol%), facile recovery of the catalyst (using an
external magnet) and its non-leaching nature and its
high performance even after eight consecutive reaction
cycles (90%). The coordination of Pd to fuberidazole as
a novel immobilized chelating agent (bearing N in the
benzimidazolium core and O in its furyl one) may open
new venues for the design of analogous materials and
various purposes.
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Maryam Afsharpour https://orcid.org/0000-0002-5672-
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Ghassemzadeh M, Mohsenzadeh F, Afsharpour M.
Pd(0) complex of fuberidazole modified magnetic
nanoparticles: A novel magnetically retrievable
high-performance catalyst for Suzuki and Stille
C-C coupling reactions. Appl Organomet Chem.
2020;e5771. https://doi.org/10.1002/aoc.5771