A heterometal (Pd–Pb) organic framework: synthesis, structure and heterogeneous catalytic application

Article abstract of DOI:10.1002/aoc.3493

A heterometallic organic framework {Pb[Pd(bpydc)Cl₂]DMF}_n (1) (H₂bpydc = 2,2′-bipyridine-5,5′-dicarboxylic acid) was synthesized via a one-pot solvothermal method and characterized using thermogravimetric analysis, X-ray photoelectron spectroscopy as well as powder and single-crystal X-ray diffraction. The crystal structure of 1 indicates that, in metalloligand Pd(bpydc)Cl₂, every Pd atom adopts a square planar coordination mode with two chloride ions and two nitrogen atoms from bpydc, and the carboxyl groups of Pd(bpydc)Cl₂ connect Pb atoms to form a one-dimensional chain along the crystallographic a-axis, which is interlinked via metalloligands to form a two-dimensional layer structure. This complex is highly active, stable and recyclable as a catalyst for the Suzuki–Miyaura and Heck reactions of a wide range of aryl halides including electron-rich and electron-poor aryl iodides/bromides, affording the corresponding products in good to excellent yields.

Full text of DOI:10.1002/aoc.3493

Full paper
Received: 28 December 2015
Revised: 7 March 2016
Accepted: 22 March 2016
Published online in Wiley Online Library
(wileyonlinelibrary.com) DOI 10.1002/aoc.3493
A heterometal (Pd–Pb) organic framework:
synthesis, structure and heterogeneous
catalytic application
Yanwei Ren*, Ou Jiang, Jiawei Li and Hang Zeng
A heterometallic organic framework {Pb[Pd(bpydc)Cl2]DMF}n (1) (H2bpydc = 2,2′-bipyridine-5,5′-dicarboxylic acid) was synthesized
via a one-pot solvothermal method and characterized using thermogravimetric analysis, X-ray photoelectron spectroscopy as well
as powder and single-crystal X-ray diffraction. The crystal structure of 1 indicates that, in metalloligand Pd(bpydc)Cl2, every Pd
atom adopts a square planar coordination mode with two chloride ions and two nitrogen atoms from bpydc, and the carboxyl
groups of Pd(bpydc)Cl2 connect Pb atoms to form a one-dimensional chain along the crystallographic a-axis, which is interlinked
via metalloligands to form a two-dimensional layer structure. This complex is highly active, stable and recyclable as a catalyst for
the Suzuki–Miyaura and Heck reactions of a wide range of aryl halides including electron-rich and electron-poor aryl
iodides/bromides, affording the corresponding products in good to excellent yields. Copyright © 2016 John Wiley & Sons, Ltd.
Additional supporting information may be found in the online version of this article at the publisher’s web-site.
Keywords: metal–organic framework; palladium(II) complex; heterogeneous catalyst; Suzuki–Miyaura reaction; Heck reaction
MOFs that could be used as efficient and recyclable heterogeneous
catalysts for the synthesis of cyclic carbonates by the cycloaddition
Introduction
of CO2 with epoxides using the Ni(salen) moieties as Lewis acid
Homogeneous palladium (Pd)-mediated catalysts have been
catalytic sites.[23,24] Recently, the bipyridine palladium complex Pd
extensively applied in the petrochemical industry, fine chemicals
(H2bpydc)Cl2 (H2bpydc = 2,2′-bipyridine-5,5′-dicarboxylic acid) has
and other fields based on their good selectivity and catalytic
performances during the past few decades.[1–7] However, the major
been used as metalloligand to prepare MOF catalysts, such as
Pd/Ln-MOFs,[25] Pd/Y-MOF,[26] doped UiO-67 and MOF-253,[27,28]
problem with many homogeneously catalyzed organic reactions is
which all exhibit good heterogeneous catalytic activity for C-C cou-
the recycling of the catalysts from the reaction media. From the
pling reactions. Compared to many employments of MOFs as scaf-
sustainable development viewpoint, it is very important to develop
folds for the encapsulation of Pd(0) nanoparticles,[31–34] a literature
heterogeneous Pd catalysts that combine the advantages of both
homogeneous and heterogeneous catalysis.[8] Heterogenization
survey shows that there are only a few examples reporting the syn-
thesis of MOFs incorporating molecular Pd(II) complexes as hetero-
of homogeneous catalysts, through immobilizing active complexes
geneous catalysts.[25–28,35,36]
on supports,[9–12] has been shown to be a promising method for
preparing heterogeneous catalysts with higher activity and
recyclability.
Herein, we present the synthesis and characterization of a new
stable heterometallic organic framework {Pb[Pd(bpydc)Cl2]DMF}n
(1). This complex shows high activity in the Suzuki–Miyaura
reaction (SMR) and Heck reaction (HR) of a variety of aryl bromides.
Importantly, Pd(II) leaching is largely inhibited due to the binding
interaction between Pd(II) and the MOF framework, which renders
1 recoverable and reusable for at least five cycles with slight loss
of catalytic efficiency.
Metal–organic frameworks (MOFs) have attracted tremendous
interests[13] and an enormous amount of MOFs have been
designed and synthesized for energy-, environment- and
medicine-relevant applications, such as gas sorption,[14]
luminescence,[15] sensors[16] and so on. Especially, MOFs used as
heterogeneous catalysts have been developed dramatically during
the past decade and many MOF-based catalysts containing various
types of catalytic sites have been reported.[17–30] Among them, the
most intensively investigated topic is MOF-based Lewis acid
catalysts that utilize the coordinatively unsaturated metal centers
in MOFs. However, these MOF catalysts often suffer from the
possible collapse of frameworks after catalytic reaction since the
coordinatively unsaturated metal centers are also responsible for
the stability of the frameworks. To overcome this problem, a more
rational strategy is to utilize metalloligands involving well-defined
catalytic sites rather than pure organic ligands to construct MOF
catalysts.[22–30] For example, we have reported two Ni(salen)-based
*
Correspondence to: Yanwei Ren, School of Chemistry and Chemical Engineering,
South China University of Technology, Guangzhou, 510641, China. E-mail:
renyw@scut.edu.cn
School of Chemistry and Chemical Engineering, South China University of
Technology, Guangzhou, 510641, China
Appl. Organometal. Chem. (2016)
Copyright © 2016 John Wiley & Sons, Ltd.

Y. Ren et al.
Typical procedure for HR
Experimental
A 20 ml glass vessel was charged with 1 (0.5 mol%), aryl halide
derivatives (0.5 mmol), olefin (0.75 mmol), Et3N (1.5 mmol) and
DMF (5 ml). The reaction mixture was stirred at the desired
temperature under nitrogen atmosphere. After the mixture was
cooled to room temperature, the solution was filtered and
concentrated under vacuum. The crude residue was purified by
flash silica gel chromatography to afford pure product, which was
identified using GC–MS, 1H NMR and 13C NMR analyses.
General methods
Unless otherwise noted, all commercial reagents and solvents were
used without further purification. Elemental analyses for C, H and N
were carried out using a Vario EL III elemental analyzer. Infrared (IR)
spectra were measured with a Nicolet Nexus 470 FT-IR spectrome-
ter in the range 400–4000 cmÀ1. NMR spectra were obtained with a
Bruker AM-400 (400 MHz) spectrometer using tetramethylsilane as
an internal standard. Powder X-ray diffraction (PXRD) patterns were
collected using a Bruker D8 powder diffractometer at 40 kV, 40 mA
with Cu Kα radiation (λ = 1.5406 Å), with a scan speed of 17.7 s per
step and a step size of 0.02° (2θ). Thermogravimetric analysis (TGA)
was performed with a Q600 SDT instrument under a flow of
nitrogen at a heating rate of 10 °C minÀ1 from ambient
temperature to 800 °C. X-ray photoelectron spectroscopy (XPS)
was performed using a Kratos Axis Ultra DLD system with a base
pressure of 10À9 Torr. The morphology of 1 was investigated using
a cold field emission scanning electron microscope (SEM; S-4800,
Hitachi). The content of Pd(II) ions was determined using
inductively coupled plasma atomic emission spectrometry (TJA
IRIS(HR)). GC–MS was conducted using a Shimadzu GCMSQP5050A
system that was equipped with a 0.25 mm × 30 m DB-WAX capillary
column.
Typical procedure for catalyst recovery
Once the reaction was finished, the mixture was centrifuged and
the solvent was removed using a syringe with a syringe filter. The
washing/centrifugation sequence was repeated four additional
times until no product was detected in the liquid phase using
TLC. The residual solvent was removed under reduced pressure
affording the recovered 1, which was directly used in the same tube
with fresh reagents for the next run.
Results and discussion
Synthesis and crystal structure of 1
Firstly, reaction of Pd(CH3CN)2Cl2 and H2bpydc in DMF and EtOH at
room temperature afforded Pd(bpydc)Cl2 as a metalloligand, in
which Pd(II) ion might preferentially coordinate to the two nitrogen
atoms of H2bpydc according to hard–soft acid–base theory.
Subsequently, oxophilic metal Pb(II) ions were added and
coordinated to the carboxylate groups of the metalloligand to
afford yellow rod-like crystals of 1 under solvothermal conditions.
The product is stable in air atmosphere and insoluble in water
and common organic solvents. TGA of 1 indicates that it is
thermally stable up to 240 °C, and a weight loss of 9.7% at about
240–285 °C (Fig. 1) corresponds to the loss of one DMF molecule.
SEM observation indicates that the solid sample of 1 consists of
rod-like crystallites on a scale of 200 μm (Fig. 2). The experimental
PXRD pattern of 1 is in agreement with the simulated pattern,
which indicates that the structure of the bulk sample is the same
as that of the single crystal (Fig. 3).
Single-crystal X-ray diffraction data for 1 were collected with a
Rigaku Mercury CCD diffractometer using Mo Kα radiation. The
empirical absorption corrections were performed using the
CrystalClear program. The structure was solved by a direct method
and refined on F2 by the full-matrix least-squares technique using
the SHELXTL-97 program package. All non-hydrogen atoms were
refined with anisotropic displacement parameters. Hydrogen
atoms attached to carbon were placed in geometrically idealized
positions and refined using a riding model. Crystal data are given in
Table 1. The selected bond distances and angles are listed in Table
S1 (supporting information). CCDC: 1406659.
Synthesis of {Pb[Pd(bpydc)Cl2]DMF}n (1)
A mixture of H2bpydc (24 mg, 0.1 mmol) and Pd(CH3CN)2Cl2 (26 mg,
0.1 mmol) in a solution of DMF (5 ml) and EtOH (0.5 ml) was stirred
at 25 °C for 1 h. Then, Pb(NO3)2 (33 mg, 0.1 mmol) was added to the
solution. The resulting mixture was sealed in a 10 ml tube and
heated to 90 °C, at which temperature it was held for 72 h. The
produced yellow rod-like crystals of 1 were filtered, washed with
DMF and EtOH, and dried at ambient temperature. Yield: 63 mg,
0.09 mmol, 90%. Anal. Calcd for C15H13Cl2N3O5PbPd (%): C, 25.74;
H, 1.87; N, 6.00. Found (%): C, 25.18; H, 1.75; N, 6.11. IR (KBr, cmÀ1):
3449(s), 1614(m), 1558(m), 1379(s), 1128(w), 1049(m), 849(m), 776
(m), 710(m).
Single-crystal X-ray diffraction study reveals that every Pd atom
adopts a square planar coordination mode with two chloride ions
and two nitrogen atoms from bpydc (Fig. 4(a)). Each Pb atom is
coordinated by six oxygen atoms from four separate carboxylate
metalloligands, and one oxygen-coordinated DMF molecule,
adopting
a distorted seven-coordinated capped octahedral
geometry. All carboxyl groups of metalloligand Pd(bpydc)Cl2 adopt
a κ1-κ2-μ2 mode to connect the Pb atoms to one-dimensional chain
along the crystallographic a-axis (Fig. 4(b)), which is interlinked via
metalloligands to form a two-dimensional layer structure (Fig. 4
(c)). The adjacent Pd(bpydc)Cl2 planes locate in the inverse parallel
position with short PdÁÁÁPd interactions (4.536 Å), as is reported that
square planar Pd(II) centers have a tendency to aggregate in the
solid state.[37]
Typical procedure for SMR
A 20 ml glass vessel was charged with 1 (0.5 mol%), aryl halide
derivatives (0.5 mmol), phenylboronic acid (0.6 mmol), K2CO3
(0.75 mmol) and toluene (5 ml). The reaction mixture was stirred
at the desired temperature under nitrogen atmosphere. After the
mixture was cooled to room temperature, the solution was filtered
and washed with brine, dried over anhydrous MgSO4 and
concentrated under vacuum. The crude residue was purified by
flash silica gel chromatography to afford pure product, which was
identified using GC–MS, 1H NMR and 13C NMR analyses.
SMR catalyzed by 1
The Pd-catalyzed SMR is well known as an effective method for
forming C-C bonds in organic synthesis. The initial studies were fo-
cused on the SMR of aryl halide derivatives with phenylboronic acid
to evaluate the catalytic activity of 1 (Scheme 1). Firstly, the cou-
pling reaction between bromobenzene and phenylboronic acid
wileyonlinelibrary.com/journal/aoc
Copyright © 2016 John Wiley & Sons, Ltd.
Appl. Organometal. Chem. (2016)

Heterometal(Pd-Pb) organic framework
Table 1. Crystal data and structure refinements for 1
Empirical formula
C15H13Cl2N3O5PbPd
Formula weight
Temperature (K)
Wavelength (Å)
Crystal system
Space group
699.77
293
0.71073
Monoclinic
P21/n
a = 15.578(3) Å; α = 90°
b = 7.5968(15)Å; β = 114.00(3)°
c = 17.030(3) Å; γ = 90°
1841.2(6)
Volume (Å3)
Z
4
Density (calcd g cmÀ3
)
2.524
Absorption coeff. (mmÀ1
F(000)
)
10.432
Figure 2. SEM image of 1.
1304
Crystal color and shape
θ range data collection
Limiting indices
Yellow, rod-like
2.99 to 27.47
bpy molecule in Pd(bpy)Cl2. These results showed that the Pd(II)
ions in 1 are catalytic active centers for the SMR.
À20 ≤ h ≤ 20, À9 ≤ k ≤ 9, À21 ≤ l ≤ 21
14 719
Reflections collected
Unique
The scope of 1-catalyzed coupling reactions of a variety of aryl
halides with phenylboronic acid was further investigated. As
evident from Table 3, 1 could catalyze the coupling reactions very
well for various aryl bromides bearing electron-withdrawing
groups, such as -CN and -COMe, while relatively low yields were ob-
tained when aryl bromides bearing electron-donating substituents
(-Me and -OMe) were used. These results are in agreement with the
known general conclusion that electron-deficient aryl bromides
exhibit higher activity than electron-rich ones. Iodobenzene and
4-iodoanisole are active under the standard conditions, giving cor-
responding products with excellent yields (Table 3, entries 6 and 7).
Compared with the high reactivity of aryl iodides/bromides, using
chlorobenzene derivatives as substrate led to very much lower
yields (Table 3, entries 9 and 10), perhaps owing to the higher bond
energy of the C-Cl bond.
4086 [R(int) = 0.0622]
Full-matrix least-squares on F2
4086/0/244
Refinement method
Data/restraints/parameters
Goodness-of-fit on F2
Final R indices [I > 2σ(I)]
R indices (all data)
1.084
R1 = 0.0445, wR2 = 0.1037
R1 = 0.0489, wR2 = 0.1111
was selected as a model reaction in order to screen the reaction pa-
rameters. After several reaction variables such as base, temperature,
time and solvent were investigated (Table 2), the optimized reac-
tion conditions involved phenylboronic acid, aryl halide and
K2CO3 as base in toluene in the presence of 0.5 mol% of 1 at
100 °C (Table 2, entry 3). A blank control shows that no expected
product was obtained when the coupling reaction between
bromobenzene and phenylboronic acid was performed in the ab-
sence of catalyst (Table 2, entry 5). In addition, under the optimized
HR catalyzed by 1
conditions,
a
three-dimensional Pd-free MOF, namely [Pb
The Pd-catalyzed HR between olefins and aryl halides is also an
important reaction for the formation of C-C bonds in synthetic
chemistry. Thus, the catalytic activity of 1 for HR of aryl halides with
olefins was examined (Scheme 2). Firstly, we chose bromobenzene
and styrene as a model reaction to screen the reaction parameters.
An excess of olefin with respect to aryl halide was used to avoid the
(bpdc)]n[38] (bpdc =4,4′-biphenyldicarboxylic acid), gave no conver-
sion for this reaction, confirming the need for Pd to perform the
coupling reaction (Table 2, entry 9). When the same amount of Pd
(bpy)Cl2 (bpy = 2,2′-bipyridine)[39] as homogeneous catalyst was
used to replace 1, the yield decreased slightly (Table 2, entry 10).
The higher activity of 1 compared to its homogeneous counterpart
could be related to the surface effect of MOF and the difference in
the electron configuration of the bpydc moiety in 1 from that of the
Figure 3. PXRD patterns of 1: (a) simulated pattern from crystal structure;
(b) as-synthesized sample; (c) after the SMR for one-run catalysis cycle; (d)
after the HR for one-run catalysis cycle.
Figure 1. TGA curve of 1.
Appl. Organometal. Chem. (2016)
Copyright © 2016 John Wiley & Sons, Ltd.
wileyonlinelibrary.com/journal/aoc

Y. Ren et al.
Table 3. SMR of various aryl halides catalyzed by 1a
Entry
Aryl halides
Yield (%)b
1
2
3
4
5
6
7
8
9
10
C6H5Br
4-CNC6H5Br
4-CH3COC6H5Br
4-CH3C6H5Br
4-CH3OC6H5Br
C6H5I
92
96
95
90
85
98
96
<5
<5
9
4-CH3OC6H5I
C6H5Cl
4-CH3OC6H5Cl
4-CH3COC6H5Cl
aReaction conditions: aryl halides (0.5 mmol), phenylboronic acid
(0.6 mmol) and K2CO3 (0.75 mmol) under nitrogen atmosphere, 6 h.
bPure product isolated yield after purification by flash column
Figure 4. Crystal structure of 1: (a) Pd(bpydc)Cl2 moiety; (b) [PbO2]∞ chain;
(c) two-dimensional framework formed by the interlink of [PbO2]∞ chains.
Grey, C; blue, N; red, O; green, Cl; purple blue, Pd; yellow grey, Pb.
chromatography.
comparison, under the optimized conditions (Table 4, entry 6), a
blank control indicates that no product was obtained in the ab-
sence of catalyst (Table 4, entry 8), and also the Pd-free MOF [Pb
(bpdc)][38] presented no any activity in this reaction (Table 4, entry
9). The homogeneous counterpart Pd(bpy)Cl2 gave reduced yield
(Table 4, entry 10), as in the SMR. These results showed that the
Pd(II) ions in 1 are catalytic active centers for the HR.
Scheme 1. General scheme for the SMR catalyzed by 1.
Similarly, under the optimized conditions, the presence of
electron-withdrawing groups (CN and COMe) in the para position
of aryl bromides was beneficial to the occurrence of this reaction
(Table 5, entries 2 and 3), while in the presence of electron-donating
substituents, the yields decreased significantly (Table 5, entries 4
and 5). Due to the higher bond energy of the C-Cl bond, aryl chlo-
rides are difficult to activate (Table 5, entries 8 and 9). Furthermore,
various alkenes, such as 4-methylstyrene, methyl acrylate and ethyl
acrylate, reacted successfully with bromobenzene, giving the corre-
sponding products in excellent yields (Table 5, entries 10–12).
formation of homocoupling by-products. The reaction proceeded
smoothly after 12 h when DMF was used as solvent and K2CO3
was used as base under nitrogen atmosphere, which afforded the
desired product in 82% yield (Table 4, entry 3). An increase of tem-
perature from 100 to 120 °C did not promote the reaction signifi-
cantly (Table 4, entry 4). The use of DMF–EtOH mixture as solvent
was not obviously effective for this reaction (Table 4, entry 5), al-
though it was reported that alcohol can act as a hydrogen bond do-
nor and then promote the break of halides and facilitate HR.[40] The
substitution of K2CO3 by the organic base Et3N enhanced the yield
markedly (Table 4, entry 6), partly owing to the good solubility and
the stabilization effect of Et3N for the Pd species.[41] When Et3N was
used as solvent and no additional base was added, the reaction also
proceeded well with a yield of 91% (Table 4, entry 7). For
Catalyst stability and recyclability
A crucial issue for heterogeneous catalysts is the possibility that
some of active sites can migrate from the solid support to the liquid
phase and these leached species could become responsible for a
significant part of the catalytic activity. Therefore, leaching tests
were performed to estimate whether the active Pd species in 1
would leach easily from MOF to the liquid phase during the
catalytic reaction. Firstly, when a model reaction (bromobenzene
and phenylboronic acid in the SMR) had taken place for 1 h with
a yield of about 25% for biphenyl, the reaction solution was split
into two fractions, in which one had the catalyst while the other
was without the catalyst. As shown in Fig. 5, after an additional
5 h, the yields of biphenyl of the two fractions are 95% (with
catalyst) and 24% (without catalyst). These results undoubtedly
indicate that 1 has a good heterogeneous nature and no active
Table 2. Optimization of SMR of bromobenzene and phenylboronic
acida
Entry
Catalyst
Solvent
Base
T (°C) Time (h) Yield (%)b
1
2
3
4
5
6
7
8
9
10
1
1
DMF
K2CO3
K2CO3
K2CO3
—
100
100
100
100
100
4
4
68
82
95
0
Toluene
Toluene
Toluene
Toluene
1
6
1
—
6
K2CO3
6
0
1
Toluene Na2CO3 100
6
85
78
86
0
1
Toluene
Toluene
K2CO3
K2CO3
K2CO3
K2CO3
80
80
6
1
12
6
[Pb(bpdc)] Toluene
Pd(bpy)Cl2 Toluene
100
100
6
80
aReaction conditions: bromobenzene (0.5 mmol), phenylboronic acid
(0.6 mmol) and base (0.75 mmol) under nitrogen atmosphere.
bYield of coupling product determined by GC–MS.
Scheme 2. General scheme for the HR catalyzed by 1.
wileyonlinelibrary.com/journal/aoc
Copyright © 2016 John Wiley & Sons, Ltd.
Appl. Organometal. Chem. (2016)

Heterometal(Pd-Pb) organic framework
Table 4. Optimization of HR of bromobenzene and styrenea
Entry Catalyst
Solvent
Base T (°C) Time (h) Yield (%)b
1
2
3
4
5
6
7
8
9
10
1
DMF
DMF
DMF
DMF
K2CO3 100
K2CO3 100
K2CO3 100
K2CO3 120
4
8
56
65
82
85
80
96
91
0
1
1
12
12
12
12
12
12
12
12
1
1
DMF + EtOH K2CO3 100
1
1
DMF
Et3N
DMF
DMF
DMF
Et3N
—
100
100
100
100
100
—
Et3N
Et3N
Et3N
[Pb(bpdc)]
Pd(bpy)Cl2
0
82
aReaction conditions: bromobenzene (0.5 mmol), styrene (0.75 mmol)
and base (1.5 mmol) under nitrogen atmosphere.
bYield of coupling product determined by GC–MS.
Figure 5. Leaching tests for the SMR of bromobenzene and phenylboronic
acid.
at least to a great extent, since the color change of the catalyst
related to Pd(0) formation was not observed during the reaction.
To further confirm that the Pd remained in its divalent form after
the catalytic reactions, we performed XPS analysis for
as-synthesized 1 and the recovered 1 after being used in the
SMR. They both exhibit a Pd 3d5/2 band at around 338 eV and a
Pd 3d3/2 band at around 343.5 eV (Fig. 7), respectively, which are
characteristic of divalent Pd.[26–28] Moreover, XPS analysis showed
that the Pb and Pd contents of the recovered 1 are 2.01 and
2.16 at.%, respectively. These results illustrate that 1 was stable
and recyclable under the investigated reaction conditions.
Therefore, based on the above studies, a plausible mechanism is
suggested in that the coupling reaction the Pd(II) of 1 seems to
undergo a reversible process, in which Pd(II) is reduced to Pd(0)
and immediately oxidized back to the initial Pd(II) state in situ after
the catalytic cycle. The role of Pb(II) of 1 is only to maintain the
stability of the MOF framework that can be considered as a polymer
ligand to bind Pd(II) ions, preventing the formation of Pd(0)
nanoparticles and the agglomeration of Pd(0) species into Pd black.
species leached into the liquid phase under catalytic conditions.
Similarly, the heterogeneous nature of 1 was also verified in the
HR using leaching tests (Fig. S4, supporting information). In
addition, only a trace of dissolved Pd (32 ppb for the SMR and
45 ppb for the HR) could be detected in the filtrate after catalytic
reaction. These results indicated that the loss of Pd species was
negligible, and the coupling reactions would proceed on the MOF
catalyst surface.
Another important advantage of heterogeneous catalysts is their
recyclability. Therefore, tests of the recyclability of 1 were carried
out using model reactions, i.e. the SMR of bromobenzene and
phenylboronic acid and the HR of bromobenzene and styrene.
After each cycle, the catalyst could be easily recovered by
centrifugation to remove the supernatant, and then washed with
toluene (or DMF) several times. As depicted in Fig. 6, the recovered
catalyst was subsequently used in five successive cycles with only
slight loss of catalytic efficiency. PXRD patterns of the reused
catalyst showed that the structural integrity of the MOF framework
was mostly maintained after the catalytic reaction (Fig. 3).
Moreover, reduction of Pd(II) ions to Pd(0) clusters (Pd black
formation is a general process for Pd catalysts) could be excluded
Conclusions
In summary, we have successfully synthesized a new two-
dimensional heterometallic (Pb–Pd) organic framework via a one-
pot solvothermal method. This complex is highly active, stable
and recyclable for the SMR and HR of a wide range of aryl halides
Table 5. HR of various aryl halides and olefins catalyzed by 1a
Entry
Aryl halides
Olefin
Yieldb (%)
1
C6H5Br
4-CNC6H5Br
4-CH3COC6H5Br
4-CH3C6H5Br
4-CH3OC6H5Br
C6H5I
Styrene
Styrene
96
96
95
60
52
91
95
<5
<5
92
96
93
2
3
Styrene
4
Styrene
5
Styrene
6
Styrene
7
4-CH3OC6H5I
C6H5Cl
Styrene
8
Styrene
9
4-CH3COC6H5Cl
C6H5Br
Styrene
10
11
12
4-Methylstyrene
Methyl acrylate
Ethyl acrylate
C6H5Br
C6H5Br
aReaction conditions: aryl halides (0.5 mmol), olefins (0.75 mmol) and
Et3N (1.5 mmol) under nitrogen atmosphere, 12 h.
bPure product isolated yield after purification by flash column
Figure 6. Recyclability of
1 in the SMR of bromobenzene and
chromatography.
phenylboronic acid and the HR of bromobenzene and styrene.
Appl. Organometal. Chem. (2016)
Copyright © 2016 John Wiley & Sons, Ltd.
wileyonlinelibrary.com/journal/aoc

Y. Ren et al.
[13] H. Furukawa, K. E. Cordova, M. O’Keeffe, O. M. Yaghi, Science 2013, 341,
974–974.
[14] S. Gadipelli, Z. X. Guo, Chem. Mater. 2014, 26, 6333–6338.
[15] J. Heine, K. Muller-Buschbaum, Chem. Soc. Rev. 2013, 42, 9232–9242.
[16] Z. C. Hu, B. J. Deibert, J. Li, Chem. Soc. Rev. 2014, 43, 5815–40.
[17] A. Dhakshinamoorthy, A. M. Asiri, H. Garcia, Chem. Soc. Rev. 2015, 44,
1922–1947.
[18] J. W. Liu, L. F. Chen, H. Cui, J. Y. Zhang, L. Zhang, C. Y. Su, Chem. Soc. Rev.
2014, 43, 6011–6061.
[19] M. Zhao, S. Ou, C. D. Wu, Acc. Chem. Res. 2014, 47, 1199–1207.
[20] L. Q. Ma, C. Abney, W. B. Lin, Chem. Soc. Rev. 2009, 38, 1248–1256.
[21] Y. W. Ren, J. X. Lu, O. Jiang, X. F. Cheng, J. Chen, Chin. J. Catal. 2015, 36,
1949–1956.
[22] J. A. Johnson, J. Luo, X. Zhang, Y. S. Chen, M. D. Morton, E. Echevería,
F. E. Torres, J. Zhang, ACS Catal. 2015, 5, 5283–5291.
[23] Y. W. Ren, Y. C. Shi, J. X. Chen, S. R. Yang, C. R. Qi, H. F. Jiang, RSC Adv.
2013, 3, 2167–2170.
[24] Y. W. Ren, X. F. Cheng, S. R. Yang, C. R. Qi, H. F. Jiang, Q. P. Mao, Dalton
Trans. 2013, 42, 9930–9937.
Figure 7. XPS spectra of 1 and of 1 recovered after SMR.
[25] S. L. Huang, A. Q. Jia, G. X. Jin, Chem. Commun. 2013, 49, 2403–2405.
[26] J. P. Huang, W. Wang, H. X. Li, ACS Catal. 2013, 3, 1526–1536.
[27] L. Y. Chen, S. Rangan, J. Li, H. F. Jiang, Y. W. Li, Green Chem. 2014, 16,
3978–3985.
[28] L. Y. Chen, Z. Q. Gao, Y. W. Li, 122–128. Catal. Today 2015, 245, 122–128.
[29] C. Zou, Z. J. Zhang, X. Xu, Q. H. Gong, J. Li, C. D. Wu, J. Am. Chem. Soc.
2012, 134, 87–90.
including electron-rich and electron-poor aryl iodides/bromides,
affording the corresponding products in good to excellent yields.
A further study of catalytic applications of this MOF for other
Pd-catalyzed transformations is in progress.
[30] F. J. Song, C. Wang, J. M. Falkowski, L. Q. Ma, W. B. Lin, J. Am. Chem. Soc.
2010, 132, 15390–15398.
[31] A. Dhakshinamoorthy, H. Garcia, Chem. Soc. Rev. 2012, 41, 5262–5284.
[32] L. Y. Chen, H. R. Chen, R. Luque, Y. W. Li, Chem. Sci. 2014, 5, 3708–3714.
[33] Q. L. Zhu, J. Li, Q. Xu, J. Am. Chem. Soc. 2013, 135, 10210–10213.
[34] B. Z. Yuan, Y. Y. Pan, Y. W. Li, B. L. Yin, H. F. Jiang, Angew. Chem. Int. Ed.
2010, 49, 4054–4058.
[35] K. Manna, T. Zhang, W. B. Lin, J. Am. Chem. Soc. 2014, 136, 6566–6569.
[36] A. M. Bohnsack, I. A. Ibarra, V. I. Bakhmutov, V. M. Lynch,
S. M. Humphrey, J. Am. Chem. Soc. 2013, 135, 16038–16041.
[37] M. G. Campbell, D. C. Powers, J. Raynaud, M. J. Graham, P. Xie, E. Lee,
T. Ritter, Nat. Chem. 2011, 3, 949–953.
Acknowledgements
This study was supported by the National Natural Science
Foundation of China (no. 21372087) and the China Postdoctoral
Science Foundation (2015 M582379).
References
[38] R. R. Hu, H. Cai, J. H. Luo, Inorg. Chem. Commun. 2011, 14, 433–436.
[39] E. J. Gao, H. X. Yin, M. C. Zhu, Y. G. Sun, X. F. Gu, Q. Wu, L. X. Ren, J. Struct.
Chem. 2008, 49, 1048–1054.
[40] J. Ruan, J. A. Iggo, N. G. Berry, J. L. Xiao, J. Am. Chem. Soc. 2010, 132,
16689–16699.
[1] D. Zhang, Q. R. Wang, Coord. Chem. Rev. 2015, 286, 1–16.
[2] C. Deraedt, D. Astruc, Acc. Chem. Res. 2014, 47, 494–503.
[3] R. Chinchilla, C. Najera, Chem. Rev. 2014, 114, 1783–1826.
[4] W. Q. Wu, H. F. Jiang, Acc. Chem. Res. 2012, 45, 1736–1748.
[5] A. Balanta, C. Godar, C. Claver, Chem. Soc. Rev. 2011, 40, 4973–4985.
[6] C. Torborg, M. Beller, Adv. Synth. Catal. 2009, 351, 3027–3043.
[7] K. C. Nicolaou, P. G. Bulger, D. Sarlah, Angew. Chem. Int. Ed. 2005, 44,
4442–4489.
[41] V. Caló, A. Nacci, A. Monopoli, S. Laera, N. Cioffi, J. Org. Chem. 2003, 68,
2929–2933.
[8] M. Flytzani-Stephanopoulos, B. C. Gates, Annu. Rev. Chem. Biomol. Eng.
2012, 3, 545–574.
[9] M. R. Maurya, A. Kumar, J. C. Pessoa, Coord. Chem. Rev. 2011, 255,
2315–2344.
[10] A. E. C. Collis, I. T. Horvath, Catal. Sci. Technol. 2011, 1, 912–919.
[11] J. M. Fraile, J. I. Garcia, J. A. Mayoral, Chem. Rev. 2009, 109, 360–417.
[12] P. McMorn, G. J. Hutchings, Chem. Soc. Rev. 2004, 33, 108–122.
Supporting Information
Additional supporting information may be found in the online ver-
sion of this article at the publisher’s web site.
wileyonlinelibrary.com/journal/aoc
Copyright © 2016 John Wiley & Sons, Ltd.
Appl. Organometal. Chem. (2016)