[60]Fullerene-Based Pd(0) Complexes of Phosphorus Ylides as Efficient Nanocatalyst for Homo- and Heterogeneous Mizoroki–Heck Coupling Reactions

Article abstract of DOI:10.1007/s10562-017-2147-9

Abstract: This work reports the synthesis and catalytic properties of new mono- and bidentate palladium(0)-[60]fullerene complexes, prepared by reaction of α-keto stabilized phosphorus ylides [Ph₂P(CH₂)_nPPh₂=C(H)C(O)C₆H₄-p-R] (n = 1, R = Ph, NO₂, (Y¹, Y²); n = 2, R = Ph, NO₂, (Y³, Y⁴)), C₆₀ and Pd(dba)₂ (dibenzylideneacetone (dba)). Two coordination modes were observed: bidentate P,C-coordinated in the case of [(η ?C₆₀)Pd(κ² ?Y¹)] (1) and [(η²?C₆₀)Pd(κ²?Y²)] (2) and monodentate P-coordinated for [(η²?C₆₀)Pd(Y³)₂] (3) and [(η²?C₆₀)Pd(Y⁴)₂] (4) complexes. All complexes have been fully characterized by ¹H, ¹³C and ³¹P NMR spectroscopic methods and other conventional techniques such as IR, thermogravimetry, inductively coupled plasma optical emission spectroscopy, scanning electron microscopy, energy-dispersive X-ray spectroscopy and transmission electron microscopy analysis. Also, the catalytic activity of [60]fullerene-based nanocatalyst 2 in homo- and heterogeneous Mizoroki–Heck coupling reactions of various aryl chlorides with styrene was evaluated. The results implied that the both reactions exhibit their beneficial aspects such as high activity for homogeneous catalysis and facile separation and reusability for heterogeneous one. Furthermore, DFT studies of geometry-optimized monodentate and bidentate structures for 1 and 3 were calculated at the BP86/LANL2DZ and B3LYP/LANL2MB levels of theory to understand the origin of the observed coordination modes. Graphical Abstract: [Figure not available: see fulltext.].

Full text of DOI:10.1007/s10562-017-2147-9

Catal Lett
DOI 10.1007/s10562-017-2147-9
[60]Fullerene-Based Pd(0) Complexes of Phosphorus Ylides
as Efficient Nanocatalyst for Homo- and Heterogeneous
Mizoroki–Heck Coupling Reactions
Seyyed Javad Sabounchei1 · Ali Hashemi1 · Marjan Hosseinzadeh1 ·
Sadegh Salehzadeh1 · Farahnaz Maleki1
Received: 11 March 2017 / Accepted: 15 July 2017
© Springer Science+Business Media, LLC 2017
Abstract This work reports the synthesis and catalytic
properties of new mono- and bidentate palladium(0)-[60]
fullerene complexes, prepared by reaction of α-keto sta-
bilized phosphorus ylides [Ph2P(CH2)nPPh2=C(H)C(O)
C6H4-p-R] (n=1, R=Ph, NO2, (Y1, Y2); n=2, R=Ph,
NO2, (Y3, Y4)), C60 and Pd(dba)2 (dibenzylideneacetone
(dba)). Two coordination modes were observed: bidentate
P,C-coordinated in the case of [(η−C60)Pd(κ2 −Y1)] (1) and
[(η2−C60)Pd(κ2−Y2)] (2) and monodentate P-coordinated
for [(η2−C60)Pd(Y3)2] (3) and [(η2−C60)Pd(Y4)2] (4) com-
plexes. All complexes have been fully characterized by 1H,
13C and 31P NMR spectroscopic methods and other conven-
tional techniques such as IR, thermogravimetry, inductively
coupled plasma optical emission spectroscopy, scanning
electron microscopy, energy-dispersive X-ray spectroscopy
and transmission electron microscopy analysis. Also, the
catalytic activity of [60]fullerene-based nanocatalyst 2 in
homo- and heterogeneous Mizoroki–Heck coupling reac-
tions of various aryl chlorides with styrene was evaluated.
The results implied that the both reactions exhibit their
beneficial aspects such as high activity for homogene-
ous catalysis and facile separation and reusability for het-
erogeneous one. Furthermore, DFT studies of geometry-
optimized monodentate and bidentate structures for 1 and
3 were calculated at the BP86/LANL2DZ and B3LYP/
LANL2MB levels of theory to understand the origin of the
observed coordination modes.
Electronic Supplementary Material The online version
of this article (doi:10.1007/s10562-017-2147-9) contains
supplementary material, which is available to authorized users.
* Seyyed Javad Sabounchei
jsabounchei@yahoo.co.uk
1
Faculty of Chemistry, Bu-Ali Sina University,
Hamedan 65174, Iran
Vol.:(0123456789)
1 3

S. J. Sabounchei et al.
Graphical Abstract
ready isolation for characterization. In addition, synthesis
of such fullerene-containing complexes offers the poten-
tial to exploit new opportunities such as chemical reactiv-
ity, redox and electron acceptor characteristics, magnetic
properties and optical activity [10, 11]. Although numer-
ous reports of exohedral metallofullerenes have appeared
in recent literature [12, 13], palladium-fullerene complexes
containing phosphorus ligands have received relatively
less attention. Among these complexes, simple mono-
and diphosphines are the most commonly used ligands to
prepare palladacyclopropa [60]fullerenes [14–18]. Our
recent studies revealed that the α-keto stabilized phos-
phorus ylides containing versatile functionalized diphos-
phines 1,1-bis(diphenylphosphino)methane (dppm) and
1,2-bis(diphenylphosphino)ethane (dppe) could coordi-
nate to Pd(0) center of palladacyclopropa[60]fullerene
Keywords [60]Fullerene · Phosphorus ylide · Reusable
nanocatalyst · Mizoroki–Heck reaction
1 Introduction
Since the discovery of [60]fullerene in 1985 by Kroto et al.
[1], coordination chemistry of transition metal-fullerene
complexes has been the focus of considerable interest from
both the synthetic and theoretical communities [2–7]. Exo-
hedral metallofullerenes, in which the metal atom is cova-
lently bonded on the outside of carbon cage [8], are found
to be synthesized more readily than the endohedral metal-
lofullerenes that encapsulate a metal atom or cluster inside
hollow carbon cage [9]. This is because of the exohedral
metallofullerenes are easy to synthesize in solution and
O
Ph2
P
Ph2
P
P
Ph2
R
Pd
Pd
PPh2
P
Ph2
R
Ph2P
R
O
O
Bidentate palladacyclopropa[60]fullerenes
containing dppm phosphorous ylide
Monodentate palladacyclopropa[60]fullerenes
containing dppe phosphorous ylide
Scheme 1 Mono- and bidentate palladacyclopropa [60]fullerenes containing dppm and dppe phosphorus ylides
1 3

[60]Fullerene-Based Pd(0) Complexes of Phosphorus Ylides as Efficient Nanocatalyst for Homo-…
complexes (Scheme 1) [19]. Different coordination behav-
ior of these ylides (P-coordination and P,C-chelation)
makes them as interesting ligands for subsequent coordina-
tion chemistry studies.
were recorded on a Perkin–Elmer FT-IR system, and sam-
ples were prepared using KBr pellets. Inductively coupled
plasma optical emission spectroscopy (ICP-OES) was per-
formed by using Varian 730-ES ICP-OES.
During the last three decades, different palladium-fuller-
ene complexes have been developed extensively as effi-
cient catalysts for a variety of reactions due to their unique
nanostructures and higher surface area than traditional Pd-
based catalysts [20–23]. Sulman and Leszczynski investi-
gated experimentally and theoretically the catalytic activity
of complex η−C60Pd(PPh3)2 in selective hydrogenation of
the acetylenic alcohols [20, 21]. Recently, the use of pal-
ladium catalysts supported on functionalized fullerene
(C60) as potential nanomediators in the formation of C–C
bonds has been also reported [24]. Veisi et al. reported the
synthesis of biguanide(metformine)-functionalized fuller-
ene (C60−Met/Pd2+) complexes and its application in the
Suzuki–Miyaura reaction [24]. Based on these studies, the
catalytic activity of palladium(0)-[60]fullerene complexes
can be investigated in the Mizoroki–Heck reaction which is
one of the fundamental palladium(0)-catalyzed C–C bond-
forming reactions [25–27].
2.2 Synthesis of Bidentate P,C-Coordinated
and Monodentate P-Coordinated Palladium(0)-[60]
Fullerene Complexes
2.2.1 General Procedure
A Schlenk tube was charged with C60 (0.05 mmol, 0.036 g)
and Pd(dba)2 (0.05 mmol, 0.029 g). Toluene (15 mL) was
added and the solution was stirred for 15 min at ambient
temperature. The purple solution turned into a black sus-
pension. Then, a solution of phosphorus ylide (0.05 mmol)
in 5 mL toluene was injected via a syringe pump to above
suspension. The system was further stirred for 2 h at room
temperature and a deep green solution was obtained. This
solution was layered with n-hexane overnight and resulting
deep green crystals were collected and washed with diethyl
ether.
Although there are many examples of catalytic systems
for the Mizoroki–Heck reaction, application of novel Pd
nanostructures as accessible, robust, and recyclable nano-
catalysts specially for aryl chlorides due to their low yield
and long reaction times is still a challenge. In continua-
tion of our interest in phosphine and nanocarbon chemistry
[19], herein, we report the synthesis, characterization and
application of new palladium(0)-[60]fullerene complexes
of mono- and bidentate phosphorus ylides systematically as
stable nanocatalysts in the Mizoroki–Heck coupling reac-
tion. The nature of metal–ligand bonds and their energetic
information in (η2−C60)Pd(Y) and (η2−C60)Pd(Y)2 (Y=Y1,
Y3) complexes have also been studied theoretically.
2.2.2 [(η2−C60)Pd(κ2−Y1)] (1)
Yield: 0.049 g (83%), M.p. >300°C. Selected IR absorp-
tion in KBr (cm−1): 527 (C60), 1651 (C=O). H NMR
1
(250.13 MHz, CDCl3) δH (ppm): 4.35 (dd, 2H, CH2,
2JP–H =27.51); 5.61 (d, H, PCH, JP–H =13.51); 7.06–8.36
2
(m, 29H, Ph). 31P NMR (101.24 MHz, CDCl3) δP
2
(ppm): 13.52 (d, PPh2, JP–P =80.15); 31.72 (d, PCH,
2JP–P =80.05). 13C NMR (62.89 MHz, CDCl3) δC (ppm):
1
34.64 (dd, PCH, JP–C =116.30); 125.28–134.78 (m, Ph);
142.13–146.29 (m, C60), 188.93 (s, CO).
2.2.3 [(η2−C60)Pd(κ2−Y2)] (2)
2 Experimental
Yield: 0.051 g (73%), M.p. >300°C. Selected IR absorp-
1
tion in KBr (cm−1): 526 (C60), 1649 (C=O). H NMR
2.1 General Considerations
(250.13 MHz, CDCl3) δH (ppm): 4.24 (dd, 2H, CH2,
2JP–H =16.00); 5.77 (br, H, PCH); 7.04–8.31 (m, 24H,
Ph). 31P NMR (101.24 MHz, CDCl3) δP (ppm): 12.99
All synthetic procedures were performed using standard
Schlenk techniques under an atmosphere of dry nitrogen
unless otherwise noted. Starting materials (C60 (+99.5%)
and Pd(dba)2) were purchased and used as received from
commercial sources. The ligands Y1–Y4 were prepared
based on the published methods [28, 29]. Toluene was dis-
tilled over a mixture of sodium/benzophenone and chloro-
form was dried over anhydrous calcium chloride and finally
distilled from P2O5 just before use. The NMR spectra
(1H, 13C and 31P) were recorded at the ambient tempera-
ture on BrukerAvance 500, 400 and 250 MHz spectrom-
eters with CDCl3 as solvent. Fourier transform IR spectra
2
2
(d, PPh2, JP–P =78.58); 31.17 (d, PCH, JP–P =78.07).
13C NMR (62.89 MHz, CDCl3) δC (ppm): 34.12 (dd,
1
1
CH2; JP–C =85.93); 36.19 (d, PCH, JP–C =57.28);
123.10–134.56 (m, Ph); 142.05–143.45 (m, C60); 194.85 (s,
CO).
2.2.4 [(η2−C60)Pd(Y3)2] (3)
Yield: 0.049 g (86%), M.p. >300°C. Selected IR absorp-
1
tion in KBr (cm−1): 518 (C60), 1578 (C=O). H NMR
(250.13 MHz, CDCl3) δH (ppm): 2.79 (m, 4H, CH2);
1 3

S. J. Sabounchei et al.
2
4.20 (d, 1H, PCH, JP–H =47.75); 7.07–8.16 (m, 29H,
is as follows: nanocatalyst 2 (0.005 mmol), aryl chloride
(0.5 mmol), styrene (0.75 mmol) and Cs2CO3 (1 mmol)
were added to 2 mL of MeOH and the resulting mixture
was stirred for 2 h. After completion of the reaction (moni-
tored by TLC), a mixture of n-hexane (4 mL), ethyl acetate
(1 mL) and water (10 mL) was added and it separates into
two layers in the decanter. The aqueous layer was further
extracted by n-hexane/ethyl acetate (80:20, 2×5 mL). The
combined organic layers were washed with saturated brine
for two times, dried over CaCl2, filtered, and concentrated
to give the desired product, which was analyzed by 1H and
13C NMR spectroscopy.
Ph). 31P NMR (101.24 MHz, CDCl3) δP (ppm): 16.46 (d,
PCH, JP–P =44.73); 17.48 (d, PPh2, JP–P =38.76). 13C
2
2
NMR (62.89 MHz, CDCl3) δC (ppm): 21.68 (m, CH2);
1
46.91 (d, PCH, JP–C =111.33); 125.29–135.53 (m, Ph);
139.70–146.94 (m, C60); 185.04 (s, CO).
2.2.5 [(η2−C60)Pd(Y4)2] (4)
Yield: 0.081 g (83%), M.p. >300°C. Selected IR absorp-
tion in KBr (cm−1): 516 (C60), 1584 (C=O). H NMR
1
(250.13 MHz, CDCl3) δH (ppm): 2.88 (m, 4H, CH2);
2
4.26 (d, 1H, PCH, JP–H =423.51); 7.06–8.54 (m, 24H,
Ph). 31P NMR (101.24 MHz, CDCl3) δP (ppm): 16.75 (d,
PCH, JP–P =43.31); 17.41 (d, PPh2, JP–P =44.02). 13C
3 Results and Discussion
2
2
NMR (62.89 MHz, CDCl3) δC (ppm): 21.66 (m, CH2);
1
49.82 (d, PCH, JP–C =109.76); 123.24–134.78 (m, Ph);
3.1 Synthesis and Characterization
141.62–148.37 (m, C60); 182.58 (s, CO).
A toluene solution of phosphorus ylides Y1 and Y2 reacted
with [C60Pdx], formed in situ from C60 and Pd(dba), to
give the new bidentate P,C-coordinated complexes 1 and 2.
Whereas, the reaction of ylides Y3 or Y4 under same condi-
tions affords monodentate P-coordinated complexes 3 and
4 (Scheme 2). Other possible side products such as P-coor-
dinated [(η2−C60)Pd(Y1)2] and [(η2−C60)Pd(Y2)2] and
also P,C-coordinated [(η2−C60)Pd(κ2−Y3)] and [(η2−C60)
Pd(κ2−Y4)] complexes have not been observed in the reac-
tions, as evidenced from spectroscopic analysis. All these
complexes were insoluble in n-hexane, which makes it
2.3 Typical Procedure for the Mizoroki–Heck Reaction
Mizoroki–Heck couplings were carried out in a round-bot-
tom flask equipped with a magnetic stir bar at room tem-
perature. In a typical homogeneous catalytic reaction, 2 mL
of a DMF solution containing palladium(0)-[60]fullerene
complex 2 (0.005 mmol), styrene (0.75 mmol), p-sub-
stituted chlorobenzene (0.5 mmol) and K2CO3 (1 mmol)
was stirred for 2 h in the presence of air. Also, the gen-
eral procedure for heterogeneous Mizoroki–Heck reaction
+
R
R
O
O
Ph
P
O
Ph
Ph
P
Ph
Ph
Ph
n=2
P
P
HC
Pd
n=1
Pd
Pd
O
P
Ph Ph
O
P
Toluene, r.t., 2h
Toluene, r.t., 2h
Ph Ph
Ph
Ph
R
+
R=Ph
R=NO2
R=Ph
R=NO2
(3)
(4)
(1)
(2)
Ph
P
O
Ph Ph
P
n
Ph
R
1
2
3
4
n=
n=
n=
n=
1, R=
1, R=NO2
2, R=Ph
Ph
(
)
)
)
)
Y
Y
Y
Y
(
(
(
2, R=NO2
Scheme 2 Synthesis of palladium(0)-[60]fullerene complexes 1–4
1 3

[60]Fullerene-Based Pd(0) Complexes of Phosphorus Ylides as Efficient Nanocatalyst for Homo-…
possible to precipitate the products as shiny black solids
via layering of n-hexane on top of the toluene solution of
products.
(SEM), transmission electron microscopy (TEM), induc-
tively coupled plasma optical emission spectroscopy (ICP-
OES), thermogravimetry (TGA) and energy-dispersive
X-ray spectroscopy (EDX) were also used for the charac-
terization of the new nanocatalyst [(η2−C60)Pd(κ2−Y2)]
(2). A brief summary of spectral data of the ligands Y1–Y4
and their palladium(0)-[60]fullerene complexes is listed in
Table 1. Comparison between the parent phosphorus ylides
and related complexes confirms the assigned composition
of the ligands and complexes.
Based on the known chemistry of palladium(0)-[60]
fullerene complexes [14–18], an implicit mechanism for the
formation of these complexes was proposed (Scheme 3).
Phosphorus ylides Y1–Y4 contain one PPh2 group attached
to ylidic carbon and one free PPh2 at the end of diphos-
phine group. In the case of phosphorus ylides Y1 and Y2,
attack of the free PPh2 to palladium(0) center of C60Pdn
polymeric complex gave the P-coordinated [(η2−C60)
Pd(Y1)] and [(η2−C60)Pd(Y2)] intermediates, which fol-
lowed by attack of carbanion to the Pd(0) and formation of
five membered P,C-coordinated complexes 1 and 2. How-
ever, in the case of phosphorus ylides Y3 and Y4, formation
of six membered P,C-coordinated complexes from P-coor-
dinated [(η2−C60)Pd(Y3)] and [(η2−C60)Pd(Y4)] inter-
mediates were not favorable, and it was led to the further
addition of second ligand and formation of P-coordinated
complexes 3 and 4.
Analysis of the IR spectra of bidentate complexes 1
and 2 and related phosphorus ylides Y1 and Y2 dem-
onstrates the high-frequency shift of ν(CO), suggesting
that the coordination of the ylides occurs simoltaneously
through the ylidic carbon and PPh2 groups [30]. Whereas,
the unchanged region of ν(CO) absorption bands in the IR
spectra of monodentate complexes 3 and 4 comparing to
parent ylides Y3 and Y4 is consistent with the coordination
of the ylides through the PPh2 groups (See Supplementary
Material). Furthermore, the IR spectra of all complexes dis-
play four characteristic absorption bands around 526, 579,
1184 and 1435 cm−1 for their C60 cores.
The structural confirmation of all new compounds (1–4)
was fully performed using Fourier transform infrared (FT-
1
1
IR), H, 13C and 31P NMR spectroscopy. Further conven-
The H NMR spectra of complexes 1–4 show the cor-
tional techniques such as scanning electron microscopy
responding signals for their respective hydrogen-containing
C
60 + Pd(dba)2
Pd
Pd
Pd
Pd
Ph
P
O
n
1
Ph Ph
n= 1, R= Ph
n= 1, R=NO2
n= 2, R=Ph
n= 2, R=NO2
(
)
)
Y
2
P
(
)
Y
Ph
3
n
(
Y
4
(
)
Y
R
R
R
O
Ph
P
Ph
P
O
Ph Ph
Pd
Ph
Ph
Ph
P
P
P
n
O
Pd
Ph
P
PhPh
Ph
HC
Pd
Ph Ph
Ph
P
R
O
R
P
Ph
Ph
R=Ph
R=NO2
(3)
(4)
R=Ph
R=NO2
(1)
(2)
n=2
n=1
R
R
O
Ph
P
Ph
P
Ph
Ph
P
O
Pd
Ph
P
P
PhPh
O
Ph Ph
Ph
Pd
R
P
Ph
Ph
Scheme 3 Proposed pathway for synthesis of complexes 1–4
1 3

S. J. Sabounchei et al.
Table 1 Spectroscopic data for
Compound
IR; ν(CO) cm−1
1H NMR; δ(PCH) 13C NMR; δ(CO)
31P NMR; δ(PCH)
and (PPh2) (ppm)
compounds Y1–Y4 and 1–4
(ppm)
(ppm)
Y1
1
1565
1651
1525
1649
1516
1578
1530
1584
4.37
5.61
4.32
5.77
4.20
4.20
4.32
4.26
184.55
188.93
181.92
194.85
183.91
185.04
182.38
182.58
11.32, −29.78
31.72, 13.52
11.52, −30.31
31.17, 12.99
16.81, −12.95
16.46, 17.48
14.71, −15.24
16.75, 17.41
Y2
2
Y3
3
Y4
4
ylidic ligands. Bidentate P,C-coordination of ylides Y1
and Y2 in palladium(0)-[60]fullerene complexes 1 and 2
is resulted in significant downfield shift of methinic pro-
ton signals, while monodentate P-coordination of ylides Y3
and Y4 in complexes 3 and 4 has not changed significantly
the values of 1H NMR chemical shifts (See Supplementary
Material). Analogously, in the 13C NMR spectra of palla-
dium(0)-[60]fullerene complexes 1 and 2, the signals attrib-
uted to the carbonyl group of phosphorus ylides Y1 and Y2
are shifted to lower field, suggesting the bidentate coordi-
nation of the ligands. Whereas in the case of complexes 3
and 4, the above signals remained unaffected comparing
to the parent ylides Y3 and Y4, indicating monodentate
coordination of the ligands (See Supplementary Material).
Also, the 13C NMR spectra of all complexes displayed the
characteristic signals around 141–147 ppm for [60]fuller-
ene skeleton.
to parent ylides, indicating that coordination of the ylides
has occurred. According to the Scheme 2, reaction of poly-
meric complex C60Pdn and phosphorus ylide Y1 or Y2 gives
the bidentate complex 1 and 2. 31P NMR spectra of these
complexes displayed a set of doublets with a large down-
field shift for the both of PPh2 and PCH phosphorus atoms
in AX pattern, while 31P NMR spectra of monodentate
complexes 3 and 4 show a different pattern as two doublets
in second order AB system (See Supplementary Material).
For investigating the size and surface morphology of
the prepared catalysts, SEM images of C60 and palla-
dium(0)-[60]fullerene complex 2 were obtained as shown
in Fig. 1. As can be seen from SEM image of C60, the parti-
cles were so strongly aggregated that discrete particles were
impossible to find and average particle size was difficult to
obtain. However, the agglomerated particles were dispersed
in SEM image of complex 2 and size of particles which
labelled in the SEM image are in the range 34.3–67.0 nm.
For further investigating the morphology and nanome-
tre scale of the prepared catalysts, TEM images of palla-
dium(0)-[60]fullerene complex 2 were obtained. The pres-
ence of spherical Pd nanoparticles is clearly distinguished
as dark spots in Fig. 2. The TEM images show that the
Aproximitally, the best probe to determine the coordi-
nation mode of phosphorus ylides in these complexes is
the study of their 31P NMR spectra and investigation of
the changes in chemical shift of phosphorus atoms upon
the complexation. The 31P chemical shift values of com-
plexes 1–4 are almost completely different with respect
Fig. 1 SEM photographs of a C60, and b palladium(0)-[60]fullerene complex 2
1 3

[60]Fullerene-Based Pd(0) Complexes of Phosphorus Ylides as Efficient Nanocatalyst for Homo-…
Fig. 2 TEM images of palladium(0)-[60]fullerene complex 2
Fig. 3 EDX analysis of palladium(0)-[60]fullerene complex 2
Fig. 4 TGA spectra of a C60, and b palladium(0)-[60]fullerene com-
plex 2
fullerene-functionalized palladium nanoparticles possess
almost spherical morphology with relatively good mono-
dispersity. The EDX measurements evidence the presence
of all individual elements as expected. Elemental spec-
trum determined from the EDX analysis is shown in Fig. 3,
which demonstrates the presence of palladium, phosphorus,
oxygen, nitrogen and carbon in the palladium nanostructure
2. Also, to obtain an insight into the accurate amount of
Pd in complex 2, the ICP-OES analysis has been applied.
According to the ICP analysis, the content of Pd in com-
plex 2 has been calculated that it to be 7.45 wt%.
the slight weight loss of absorbed solvents (1.6 wt%) below
250°C was also observed and further heating of the com-
pound from 250 to 440°C resulted in 20.8% weight loss,
mainly due to the removal of phosphorus-containing func-
tional ligand. The third weight loss occurs at temperature
range of 440–600°C, which is related to the decomposition
of fullerene (C60). Therefore, the amount of palladium on
the surface of the supporting modified-fullerene is esti-
mated to be 17.3% from the TG analysis.
In order to investigate the thermal stability of new nano-
catalyst 2, TG analysis was conducted in an inert atmos-
phere. As shown in Fig. 4a, for C60, the light mass loss
(3.7 wt%) below 250°C can be attributed to the evaporation
of absorbed solvents such as water. A thermal decomposi-
tion starting after 380°C, with a weight loss of about 96%,
can be assigned to carbon cage and amorphous carbon
decompose in fullerene. For C60-Pd(0) complex 2 (Fig. 4b),
3.2 Mizoroki–Heck Coupling Reaction of Aryl
Chlorides with Styrene
Palladium catalyzed C(sp2)–C(sp2) bond forming reactions
are seen to be performed in both homogeneous and hetero-
geneous systems [31–34]. The homogeneous catalysts show
high selectivity and produce high yields of coupled prod-
ucts; however, this system has considerable disadvantages,
1 3

S. J. Sabounchei et al.
including inability of catalyst recovery from reaction prod-
ucts and impossibility of their reuse which is led to the loss
of expensive metals and ligands [35, 36]. In order to over-
come these limitations, researchers prefer the heterogene-
ous catalysts with the beneficial aspects of good stability,
facility of separation and satisfactory reusability [37, 38].
Also, spherical palladium nanoparticles with coordination-
driven basis combine the high activity of homogeneous
catalysts and the facile separation and recycling of hetero-
geneous ones [39]. This clearly implies that the nano-sized
Pd complexes synthesized in this study are likely expected
to behave as versatile catalysts for both homogeneous and
heterogeneous catalytic systems based on their different
solubility in different reaction conditions.
give the high yields at different reaction conditions. The
optimal conditions selected for homogeneous reaction
were: DMF as solvent; K2CO3 as base; 0.005 mmol of
complex 2 and 25°C as the reaction temperature. Also, the
conditions were optimized for Mizoroki–Heck coupling
reaction in heterogeneous medium. In this case, nanocata-
lyst 2 is insoluble in methanol and exhibits heterogene-
ous catalytic activity. The reaction carried out in methanol
gives the highest yield in the presence of Cs2CO3 as base
using 0.005 mmol of nanocatalyst 2 at room temperature
(See Table S1 in Supplementary Material).
Using the optimized reaction conditions, the coupling
reactions of different aryl chlorides with styrene were
assessed in both homogeneous and heterogeneous condi-
tions. We used economical aryl chlorides with less reac-
tivity than aryl bromides and iodides in above coupling
reactions. Functionalized aryl chlorides bearing both elec-
tron-donating to electron-withdrawing groups reacted with
styrene and were converted into the corresponding coupled
products in high to excellent yields (Table 2). Conversely,
increasing the electron density on aryl chlorides lowered
In order to investigate the catalytic activity of prepared
nanocatalyst 2, the effect of different parameters such as the
type and amount of the catalyst, solvent and base system,
and reaction temperature were determined. Initially, the
reaction conditions were optimized with chlorobenzene and
styrene as the model substrates. The results revealed that
the homogeneous and heterogeneous catalytic coupling
Table 2 Mizoroki–Heck coupling reaction of aryl chlorides
Entry
1
R
Type of reaction
Homogeneous
Product
Yield (%)a
96
COCH3
(5a)
2
COCH3
Heterogeneous
94
3
4
CHO
CHO
Homogeneous
Heterogeneous
91
94
(5b)
(5c)
5
6
H
H
Homogeneous
Heterogeneous
90
87
7
8
CH3
CH3
Homogeneous
Heterogeneous
86
85
(5d)
(5e)
9
OCH3
OCH3
Homogeneous
Heterogeneous
84
81
10
Reaction conditions for homogeneous Mizoroki–Heck coupling reaction: Aryl chloride (0.5 mmol), styrene (0.75 mmol), K2CO3 (1 mmol),
DMF (2 mL), catalyst (0.005 mmol), 2 h in the air. Reaction conditions for heterogeneous Mizoroki–Heck coupling reaction: Aryl chloride
(0.5 mmol), styrene (0.75 mmol), Cs2CO3 (1 mmol), methanol (2 mL), catalyst (0.005 mmol), 2 h in the air.
aIsolated yield
1 3

[60]Fullerene-Based Pd(0) Complexes of Phosphorus Ylides as Efficient Nanocatalyst for Homo-…
the catalyst activity. For example, excellent yields were
achieved when styrene reacted with aryl chlorides hav-
ing –COCH3 and –CHO electron-withdrawing substituent
(Table 2, entries 1–4). Deactivated aryl chlorides 4-chlo-
rotoluene and 4-chloroanisol gave lower yields, indicating
that the reaction is sensitive to the electron density on aryl
chlorides (Table 2, entries 7–10). The reaction of elec-
tronically neutral chlorobenzene with styrene was also gave
good amount of the product (Table 2, entries 5 and 6).
As can be seen from Table 2, palladium(0)-[60]fullerene
complex 2 exhibited good to excellent catalytic reactivity
in both homo-and heterogeneous systems, but its catalytic
activity in homogeneous form was higher than that in het-
erogeneous form. However, recycling of complex 2 as an
important subject, cannot be performed in the DMF reac-
tion system as a homogeneous way. In order to investigate
the reusability of nanocatalyst 2, it was filtered from the
reaction media upon completion of the reaction. The recov-
ered catalyst was rinsed with methanol and dried under
reduced pressure. The results depicted in Fig. 5 confirm
that the recovered nanocatalyst 2 is almost highly active in
further coupling reactions and can be recycled and reused
several times without appreciable loss of catalytic activity.
To discern between homogeneity or heterogeneity nature
of the truly active Pd species, several techniques have been
assessed. In the first, homogeneous nature of reaction per-
formed in DMF has been checked by mercury drop test
[40]. Since Hg(0) leads to amalgamation of the surface of
metallic palladium, and in contrast, Hg(0) is not expected
to have a poisoning effect on homogeneous monometallic
LPd(0) species, the results of desired test help us to deter-
mine the nature of active species [41]. Addition of 100
equiv. Hg(0) to the reaction between chlorobenzene and
styrene (0.0005 mmol of complex 2, 1 mmol of K2CO3,
2 mL DMF, 25°C and 2 h) at t=0, did not affect signifi-
cantly the conversion of reaction (85% conversion). This
fact indicates that no Pd nanoparticles or cluster particles
is being produced and thus the catalyst is homogeneous in
nature. However, addition of a large excess (300 equiv.)
of Hg(0) to the reaction mixture suppressed the catalytic
activity, which likely attributed to the ligand dissociation
and decomposition of the palladium complex as true cata-
lytically active species. Also, the addition of 100 equiv.
Hg(0) to the reaction between chlorobenzene and styrene in
heterogeneous system (0.0005 mmol of complex 2, 1 mmol
of Cs2CO3, 2 mL methanol, 25°C and 2 h) immediately
quenched the activity of the nanocatalyst 2. This result can
be rationalized assuming that the insoluble Pd nanoparti-
cles containing phosphorus ylide ligands are responsible
for the catalytic activity and they will react with Hg(0),
which leads to decreasing the catalytic performance until
complete deactivation.
We continued our study by exploring an additional
quantitative poisoning experiment with triphenylphosphine
to determine the nature of catalytic active species. Triph-
enylphosphine could bind strongly to the palladium metal
center and block the access of substrate to the active sites
in heterogeneous catalyst [42]. In contrast, this poison does
not quench the homogeneous catalytic reaction and it usu-
ally requires more than 1.0 equiv. to completely poison a
homogeneous catalyst [43]. Homogenous catalytic reac-
tion of 0.5 mmol chlorobenzene with 0.75 mmol styrene
in presence of 1 equiv. PPh3 (reaction condition: catalysts
2 (0.001 mol%), Cs2CO3 (1.5 mmol) and DMF (2 mL))
occurred with only a 5% decrease in conversion (85% con-
version), however, more than 3.0 equiv. is required to com-
pletely poison this reaction, which reinforces the previous
inference. On the other hand, the suppression of catalytic
reaction of 0.5 mmol chlorobenzene with 0.75 mmol sty-
rene by 1 equiv. PPh3 performed in methanol (reaction con-
dition: catalysts 2 (0.001 mol%), Cs2CO3 (1.5 mmol) and
methanol (2 mL)) is evidence that this reaction mechanism
follows a heterogeneous pathway supporting the results of
the Hg(0) test.
To ascertain the presence/absence of leached and cata-
lytically active species, the Maitlis filtration test was also
performed [44]. In order to do this, both the homo- and
heterogeneous reaction pathways were set up as described
above, but the reaction mixtures were stirred for 2 h. Then,
the reaction mixtures were filtered through sintered glass
filters containing cellulose to remove the solid particles
and both the filtrates and remained solid particles in cel-
luloses were evaluated for further investigations. Addition
of a suitable base to each filtrate and stirring of the reac-
tion mixtures for 2 h revealed that the filtrate of homoge-
neous reaction was catalytically active (85% conversion).
While no coupling product was obtained in the reaction
using filtrate of heterogeneous reaction, indicating that the
amount of palladium leached from the catalyst to metha-
nol is very negligible. Another supportive evidence for this
claim is based on the results from ICP-OES analysis on the
Pd content leaching into the reaction mixture. The amount
100
80
60
40
20
0
90
86
85
84
81
Fresh
1st
2nd
3rd
4th
Number of recycles
Fig. 5 Reusability of nanocatalyst 2 in the Mizoroki–Heck coupling
reaction of chlorobenzene with styrene in methanol
1 3

S. J. Sabounchei et al.
of Pd after five runs was only 1.45 ppm, which indicated
that the catalyst was stable and leaching of Pd during the
reaction was less than 1% of the starting Pd amount. Also,
the celluloses were washed with proper solvent and were
added to the reaction mixture of chlorobenzene and styrene
in the specified reaction conditions. The results of reaction
carried out with the remained solid particles in cellulose
of heterogeneous reaction suggest that the leaching of Pd
species from the solid particles is low and it was still het-
erogeneously catalytic active (86% conversion). Whereas,
application of the remained solid particles in cellulose of
homogeneous reaction in a fresh reaction without further
addition of the catalyst gave no coupling product, which
supports the presence of soluble molecular Pd(0) spices
and homogeneous catalytic process.
loadings [45–52]. But the results observed with our catalyst
at mild reaction conditions (25°C, 2 h and 1 mol% of cata-
lyst) are still good in comparison to those reported in the
literature.
3.3 Theoretical Study
Similar to our previous work [19], density functional the-
ory was used to explore the nature of metal–ligand bonds
in (η2−C60)Pd(Y1), (η2−C60)Pd(Y3), (η2−C60)Pd(Y1)2
and (η2−C60)Pd(Y3)2 complexes and study on their rela-
tive thermodynamic stability. For this purpose, at first,
the geometry optimizations of complexes were performed
at B3LYP/LANL2MB level of theory using the Gauss-
ian 09 program [53]. Then a further calculation was per-
formed at a higher level of theory, BP86/LANL2DZ. The
results show that the structures which are optimized at less
expensive B3LYP/LANL2MB level of theory are similar to
those at BP86/LANL2DZ one. Indeed, the main difference
between the data obtained from the above level of calcula-
tions concerns to the Pd–P bond, where the values derived
of former level of theory are considerably larger than those
from latter one. The experimental values reported for Pd–P
bond length in similar complexes is about 2.3–2.4 Å, indi-
cating that the data at BP86/LANL2DZ level of theory are
In order to show the merit and efficiency of this catalyst
in both homo- and heterogeneous Mizoroki–Heck coupling
reaction of aryl chlorides, a comparison between the pre-
sent catalytic systems and other recently reported protocols
was done. As shown in Table 3, the Mizoroki–Heck reac-
tion of styrene with aryl chlorides catalyzed by the most
active homogeneous palladacycles and N-heterocyclic car-
benes (NHCs) Pd complexes and also heterogeneous Pd
nanoparticles need to use harsh reaction conditions, such as
elevated temperatures, long reaction times or high catalyst
Table 3 Comparison of Mizoroki–Heck coupling reaction of p-chloroacetopheneone and styrene using complex 2 and other catalytic systems
Entry Pd source
Catalyst
loading
(mol%)
Condition
Yield (%) Ref
1
2
3
4
5
Homogeneous Pd(0) complex of NHC and phosphine ligand
0.5
0.5
0.5
2
NaOAc, TBAB, 140°C, 2 h
NaOAc, DMAc, 130°C, 30 h
KHCO3, DMF, 140°C, 1 h
K2CO3, DMF, 130°C, 4 h
K2CO3, DMF, 25°C, 2 h
85
31
95
85
96
[45]
[46]
[47]
[48]
Homogeneous Pd(II) complex of chelating bis-NHC ligand
Homogeneous Pd(II) complex of anionic NHC ligand
Homogeneous palladacycle containing P,C-donor atoms
Homogeneous [60]fullerene-based Pd(0) complex of phospho-
1
This work
rus ylide
6
Heterogeneous Pd nanoparticles supported
on polystyrene resin
0.07
2
Na2CO3, EtOH/H2O, 120°C, 0.5 h 82
[49]
7
Heterogeneous Pd nanoparticle stabilized by [Bmim]Lac ionic
NEt3, DMF/H2O, 90°C, 24 h
NEt3, DMF, 120°C, 3 h
5
99
85
94
[50]
liquida
8
Heterogeneous Pd(II) complex of EDTA supported on SBA-15 0.87
surfacea
[51]
9
Heterogeneous Pd nanoparticles supported on phosphinated
47
K2CO3, DMF, 100°C, 6 h
Cs2CO3, MeOH, 25°C, 2 h
[52]
poly(vinyl alcohol)a
10
Heterogeneous [60]fullerene-based Pd(0) complex of phospho-
rus ylide
1
This work
ap-Nitrochlorobenzene as aryl chloride substrate has been used
1 3

[60]Fullerene-Based Pd(0) Complexes of Phosphorus Ylides as Efficient Nanocatalyst for Homo-…
in better agreement with the experimental values [54, 55].
Figure 6 shows the optimized structures of all complexes
only at BP86/LANL2DZ level, but the bond length and
bond angles of metal–ligand bonds for both B3LYP/LAN-
L2MB and BP86/LANL2DZ levels of theory are given
in Table 4. Also in Supporting Information the Cartesian
atomic coordinates of all compounds are available at both
B3LYP/LANL2MB and BP86/LANL2DZ levels of theory.
It should be noted that in these complexes the Pd atom can
be coordinated to two different types of C–C bonds in the
C60 structure. Indeed, in C60 structure there are two types
of bonds: the bonds at the junction of two hexagons, [6,6]-
bonds, and those between one pentagon and one hexagon
[5,6]-bonds. In this work, similar to our previous work [19]
Fig. 6 The optimized structures of (η2−C60)Pd(Y1), (η2−C60)Pd(Y3), (η2−C60)Pd(Y1)2 and (η2−C60)Pd(Y3)2 complexes at BP86/LANL2DZ
level of theory
1 3

S. J. Sabounchei et al.
(η2−C60)Pd Pd(Y) or Pd(Y)2
Table 4 The bond lengths [Å]
and bond angles [degree] of
metal–ligand in all complexes at
BP86/LANL2DZ (normal text)
and B3LYP/LANL2MB (Italic)
levels of theory
Complexes
(η2−C60)Pd
Pd(Y) or Pd(Y)2
l Pd-C1 l Pd-C2 l Pd-P1 l Pd-P2 or ∠C1-Pd-C2 ∠P1-Pd-P2 or ∠P1-Pd-C3
l Pd-C3
(η2−C60)Pd(Y1)
2.16
2.15
2.14
2.17
2.12
2.15
2.15
2.18
2.13
2.41
2.74
2.44
2.65
2.42
2.73
2.46
2.67
2.20
2.19
2.47
2.67
2.21
2.19
2.47
2.72
40.82
41.47
40.39
41.48
40.85
41.57
40.57
41.51
89.87
85.94
116.25
106.39
91.85
88.32
106.57
102.22
2.12
(η2−C60)Pd(Y1)2 2.16
2.12
(η2−C60)Pd(Y3)
2.16
2.11
(η2−C60)Pd(Y3)2 2.15
2.12
and based on experimental observations for similar com-
plexes, we have assumed that the Pd atom is only attached
to a [6,6]-double bond [56].
Pd‒Y bonds the contribution of ΔEelec term in total inter-
action energy is larger than ΔEorb term. However, in all
complexes the (η2−C60)‒PdY bond is more covalent in
nature compared with (η2−C60)Pd‒Y bond.
In continue, energy decomposition analysis (EDA) with
ADF 2013 program were employed for analyzing the pal-
ladium‒C60 and palladium‒Y (Y=Y1 and Y3) bonds in
(η2−C60)Pd(Y1), (η2−C60)Pd(Y3), (η2−C60)Pd(Y1)2 and
(η2−C60)Pd(Y3)2 complexes at BP86-D3/TZP//BP86/LAN-
L2DZ level of theory. The EDA decomposes the interaction
energy between two considered fragments A and B into
four terms which can be interpreted in a chemically mean-
ingful way. The four terms are including the quasiclassical
electrostatic interaction between the frozen charges of the
fragments (ΔEelec); the exchange (Pauli) repulsion between
electrons possessing the same spin (ΔEPauli); the orbital
interaction term (ΔEorb) and the dispersion contributions
(ΔEdisp).
As we saw in “Experimental” the Y1 and Y3 form the
P- and P,C-coordinated complexes, respectively. In order
to explain the difference between the complexes of Y1
and Y3 with (η2−C60)Pd we studied the following reac-
tions (1) and (2) at both B3LYP/LANL2MB and BP86/
LANL2DZ (figures in parentheses) levels of theory.
(
)
(
)
(
)
(
)
η2 − C60 Pd Y1 + Y1 → η2 − C60 Pd Y1
ΔE = +5.21 (−13.02) kcal/mol
2
(1)
(2)
(
)
(
)
(
)
(
)
η2 − C60 Pd Y3 + Y3 → η2 − C60 Pd Y3
2
ΔE = −7.19 (−37.31) kcal/mol
Indeed, in above equations the Y1 and Y3 are added
Table 5 represents the EDA results where in all com-
plexes the interaction energy values, ΔEint, between
(η2−C60)Pd and phosphorus ylide (Y1 or Y3) fragments
are somewhat larger than those between (η2−C60) and
Pd‒phosphorus ylide (Y1 or Y3) fragments. As can be
seen, the percentage contribution of ΔEelec term in the
series of studied complexes in in the range of 59–62% for
(η2−C60)Pd‒Y and 50% for (η2−C60)‒PdY bond. Indeed,
in all complexes and for both (η2−C60)‒PdY and (η2−C60)
to P,C-coordinated (η2−C60)Pd(Y1) and (η2−C60)Pd(Y3)
complexes to produce the P-coordinated (η2−C60)Pd(Y1)2
and (η2−C60)Pd(Y3)2 complexes, respectively. As can be
seen in the case of Y3, the formation of P-coordinated
(η2−C60)Pd(Y3)2 is considerably more exothermic at both
levels of theory. So it seems that the (η2−C60)Pd(Y1) and
(η2−C60)Pd(Y3)2 complexes are main products in the case
of of Y1 and Y3 ligands, respectively.
Table 5 Energy decomposition
Complexes
Fragments
ΔEint
ΔEPauli ΔEelec
ΔEorb
ΔEdisp
analysis (EDA) data [kcal/
mol] at BP86-D3/TZP//BP86/
LANL2DZ level of theory
(η2−C60)Pd(Y1) (η2−C60)Pd...(Y1) −81.00 173.97 −158.82 (62%) −74.45 (29%) −21.70 (9%)
(η2−C60)...Pd(Y1) −65.48 156.40 −111.87 (50%) −92.44 (42%) −17.57 (8%)
(η2−C60)Pd(Y1)2 (η2−C60)Pd...(Y1)2 −85.52 170.98 −155.58 (61%) −70.75 (28%) −30.17 (12%)
(η2−C60)...Pd(Y1)2 −63.80 161.90 −113.96 (50%) −86.80 (38%) −24.95 (11%)
(η2−C60)Pd(Y3) (η2−C60)Pd...(Y3) −85.46 179.63 −161.72 (61%) −77.60 (29%) −25.77 (10%)
(η2−C60)...Pd(Y3) −69.81 162.29 −115.58 (50%) −95.56 (41%) −20.95 (9%)
(η2−C60)Pd(Y3)2 (η2−C60)Pd...(Y3)2 −92.64 162.69 −151.41 (59%) −71.87 (28%) −32.05 (13%)
(η2−C60)...Pd(Y3)2 −71.65 171.28 −120.92 (50%) −95.47 (39%) −26.54 (11%)
1 3

[60]Fullerene-Based Pd(0) Complexes of Phosphorus Ylides as Efficient Nanocatalyst for Homo-…
23. Starodubtseva EV, Sokolov VI, Bashilov VV, Novikov YN, Mar-
4 Conclusions
tynova EV, Vinogradov MG, Turova OV (2008) Mendeleev Com-
mun 18:209–210
The present study describes the synthesis and catalytic
application of new palladium(0)-[60]fullerene complexes
containing unsymmetrical phosphorus ylides in simple and
convenient method. On the basis of physicochemical and
spectroscopic data, we propose that the phosphorus ylides
Y1 and Y2 coordinated to (η2−C60)Pd in bidentate P,C-
coordinated form, whereas the phosphorus ylides Y3 and Y4
coordinated to (η2−C60)Pd in monodentate P-coordinated
form. Also, the catalytic activity of nanocatalyst 2 towards
Mizoroki–Heck coupling reaction of various aryl chlorides
and styrene were investigated in homo- and heterogeneous
reactions. The results showed that palladium(0)-[60]fuller-
ene complex catalyzes Csp2–Csp2 bond-forming reactions,
and allows use of recoverable catalysts for several times,
while retaining high productivity and stability.
24. Veisi H, Masti R, Kordestani D, Safaei M, Sahin O (2014) J Mol
Catal A 385:61–67
25. Mizoroki T, Mori K, Ozaki A (1971) Bull Chem Soc Jpn
44:581–581
26. Lin Y-C, Hsueh H-H, Kanne S, Chang L-K, Liu F-C, Lin IJB, Lee
G-H, Peng S-M (2013) Organometallics 32:3859–3869
27. Smith MR, Jang YJ, Kim JY, Ciufolini MA (2013) Tetrahedron
69:10139–10151
28. Sabounchei SJ, Samiee S, Salehzadeh S, Bayat M, Nojini ZB,
MoralesMorales D (2010) Inorg Chim Acta 363:1254–1261
29. Sabounchei SJ, Samiee S, Salehzadeha S, Nojini ZB, Irran E
(2010) J Organomet Chem 695:1441–1450
30. Ebrahim MM, Panchanatheswaran K, Neels A, Stoeckli-Evans H
(2009) J Organomet Chem 694:643–648
31. Ghotbinejad M, Khosropour AR, Mohammadpoor-Baltork I,
Moghadam M, Tangestaninejad S, Mirkhani V (2014) J Mol Catal
A 385:78–84
32. Pradhan S, Dutta S, John RP (2016) New J Chem 40:7140–7147
33. Silarska E, Trzeciak AM, Pernak J, Skrzypczak A (2013) Appl
Catal A 466:216–223
Acknowledgements Funding of our research from the Bu-Ali Sina
34. Sabounchei SJ, Ahmadi M, Panahimehr M, Akhlaghi Bagherjeri F,
Nasri Z (2014) J Mol Catal A 383–384:249–259
35. Baran T, Acıksöz E, Mentes E (2015) J Mol Catal A 407:47–52
36. Nan G, Ren F, Luo M (2010) Beilstein J Org Chem 6:70
37. Fukaya N, Ueda M, Onozawa S, Bando KK, Miyaji T, Takagi Y,
Sakakura T, Yasuda H (2011) J Mol Catal A 342–343:58–66
38. Dong W, Zhang L, Wang C, Feng C, Shang N, Gaoa S, Wang C
(2016) RSC Adv 6:37118–37123
University is gratefully acknowledged.
References
1. Kroto HW, Heath JR, O′Brien SC, Curl RF, Smalley RE (1985)
Nature 318:162–163
2. Matsuo Y, Muramatsu A, Lu J, Nakamura E (2010) Chem Lett
39:342–343
39. Zhao C-W, Ma J-P, Liu Q-K, Yu Y, Wang P, Li Y-A, Wang K,
Dong Y-B (2013) Green Chem 15:3150–3154
3. Goclon J, Winklera K, Margraf JT (2017) RSC Adv 7:2202–2210
4. Kuninobu Y, Matsuo Y, Toganoh M, Sawamura M, Nakamura E
(2004) Organometallics 23:3259–3266
40. Whitesides GM, Hackett M, Brainard RL, Lavalleye J-PPM, Sow-
inski AF, Izumi AN, Moore SS, Brown DW, Staudt EM (1985)
Organometallics 4:1819–1830
5. Özdamar B, Boero M, Massobrio C, Felder-Flesch D, Le Roux S,
(2015) J Chem Phys 143:114308(1)–114308(8)
41. Hajipour MAR, Abrisham F, Tavakoli G (2011) Transit Met Chem
36:725–730
6. RobledoM, AguirreNF, Díaz-TenderoS, MartínF, AlcamíM(2014)
RSC Adv 4:53010–53020
42. Andrews SP, Stepan AF, Tanaka H, Ley SV, Smith MD (2005)
Adv Synth Catal 347:647–654
7. Konarev DV, Troyanov SI, Otsuka A, Yamochi H, Saitode G,
Lyubovskaya RN (2016) Dalton Trans 45:6548–6554
43. Hamlin JE, Hirai K, Millan A, Maitlis PM (1980) J Mol Catal
7:543–544
8. Filippone S, Martín
N (2014) Encycl Polym Nanomater.
44. Nobre SM, Monteiro AL (2009) J Mol Catal A 313:65–73
45. Lee J-Y, Shen J-S, Tzeng R-J, Lu I-C, Lii J-H, Hu C-H, Lee HM
(2016) Dalton Trans 45:10375–10388
doi:10.1007/978-3-642-36199-9_332-1
9. Popov MAA, Yang S, Dunsch L (2013) Chem Rev 113:5989–6113
10. Langa F, Nierengarten J-F (2007) ‘Fullerenes: principles and
Applications’. RSC Publication, Cambridge
46. Allolio C, Strassner T (2014) J Org Chem 79:12096–12105
47. Guest D, da Silva VHM, de Lima Batista AP, Roe SM, Braga
AAC, Navarro O (2015) Organometallics 34:2463–2470
48. Karami K, Ghasemi M, Haghighat Naeini N (2013) Tetrahedron
Lett 54:1352–1355
11. Thompson BC, Fréchet JMJ, (2008) Angew Chem Int Ed 47:58–77
12. Lebedeva MA, Chamberlain TW, Khlobystov AN (2015) Chem
Rev 115:11301–11351
13. Balch AL, Winkler K (2016) Chem Rev 116:3812–3882
14. Lerke SA, Parkinson BA, Evans DH, Fagan PJ (1992) J Am Chem
Soc 114:7807–7813
49. Shah D, Kaur H (2016) J Mol Catal A 424:171–180
50. Wang F, Tang S, Yu Y, Wang L, Yin B, Li X (2014) Chin J Catal
35:1921–1926
15. Nagashima H, Kato Y, Yamaguchi H, Kimura E, Kawanishi T,
Kato M, Saito Y, Haga M, Itoh K (1994) Chem Lett 23:1207–1210
16. Sokolov VI (2007) Russ J Coord Chem 33:711–724
17. Bashilov VV, Dolgushin FM, Petrovskii PV, Sokolov VI, Sada M,
Benincori T, Zotti G (2005) J Organomet Chem 690:4330–4336
18. Song L-C, Yu G-A, Hu Q-M, Che C-M, Zhu N, Huang J-S (2006)
J Organomet Chem 691:787–792
51. Rathod J, Sharma P, Pandey P, Singh A, Kumar P (2017) J Porous
Mater 24:837–846. doi:10.1007/s10934-016-0323-8
52. Ebrahimzadeh F, Tamami B (2015) Phosphorus Sulfur Silicon
Relat Elem 190:144–157
53. Frisch MJ et al (2009) Gaussian 09, revision A.02. Gaussian Inc.,
Wallingford, CT
54. Hirsch MA, M. Brettreich (2005) Fullerenes: Chemistry and
Reactions. Wiley, Weinheim, pp 393–393
19. Sabounchei SJ, Hosseinzadeh M, Hashemi A, Salehzadeha S,
Maleki F (2016) Dalton Trans 45:13899–13906
55. Olmstead MM, Hao L, Balch AL (1999) J Organomet Chem
578:85–90
20. Sulman E, Matveeva V, Semagina N, Yanov I, Bashilov V, Sokolov
V (1999) J Mol Catal A 146:257–263
56. Song L-C, Su F-H, Hu Q-M (2005) J Organomet Chem
690:1121–1124
21. Yanov MI, Leszczynski J, Sulman E, Matveeva V, Semagina N
(2004) Int J Quantum Chem 100:810–817
22. Goldshleger NF (2001) Fuller Sci Technol 9:255–280
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