Stable Fe(ii)-based coordination polymers: Synthesis, structural diversity and catalytic applications in homo-coupling reactions

Article abstract of DOI:10.1039/c8dt01839a

Herein, we synthesize three new stable Fe(ii) coordination polymers, {[Fe₃(tttmb)₄(OH)(NCS)₅]2CH₃OH·H₂O}_n (1), {[Fe₃(tttmb)₄(NCS)₆]·3H₂O}_n (2), and {[Fe₃(tttmb)₂Cl₆(H₂O)₆]·5H₂O}_n (3) (tttmb = 1,3,5-tris(triazole-1-ylmethyl)-2,4,6-trimethyl-benzene) under the regulation of KSCN and solvents and use them as green heterogeneous catalysts in aryl homo-coupling reactions. The catalytic experiments show that 1 and 3 exhibit high efficiency for aryl homo-coupling reactions under an air environment with a yield of up to 80%. Furthermore, the crystal structure analysis reveals that 1 and 3 have coordinated water molecules and OH^-, which are easily removed from the host materials during the reactions. In contrast, no unsaturated coordination sites are generated in 2 during the reaction process. In addition, the variable temperature magnetic susceptibilities of 1-3 prove that the metal centers of these polymers are bivalent and all of them exhibit a weak antiferromagnetic effect.

Full text of DOI:10.1039/c8dt01839a

View Article Online
View Journal
Dalton
Transactions
Accepted Manuscript
This article can be cited before page numbers have been issued, to do this please use: H. Hou, Q. Wu, Y.
Han, C. Z. Shao and J. Li, Dalton Trans., 2018, DOI: 10.1039/C8DT01839A.
This is an Accepted Manuscript, which has been through the
Volume 45 Number
1 7 January 2016 Pages 1–398
Royal Society of Chemistry peer review process and has been
accepted for publication.
Dalton
Transactions
Accepted Manuscripts are published online shortly after
An international journal of inorganic chemistry
www.rsc.org/dalton
acceptance, before technical editing, formatting and proof reading.
Using this free service, authors can make their results available
to the community, in citable form, before we publish the edited
article. We will replace this Accepted Manuscript with the edited
and formatted Advance Article as soon as it is available.
You can find more information about Accepted Manuscripts in the
author guidelines.
Please note that technical editing may introduce minor changes
to the text and/or graphics, which may alter content. The journal’s
standard Terms & Conditions and the ethical guidelines, outlined
in our author and reviewer resource centre, still apply. In no
event shall the Royal Society of Chemistry be held responsible
for any errors or omissions in this Accepted Manuscript or any
consequences arising from the use of any information it contains.
ISSN 1477-9226
PAPER
Joseph T. Hupp, Omar K. Farha et al.
Efficient extraction of sulfate from water using
framework
a Zr-metal–organic
rsc.li/dalton

Please do not adjust margins
Dalton Transactions
Page 1 of 7
View Article Online
DOI: 10.1039/C8DT01839A
Journal Name
ARTICLE
Stable Fe(II)-Based Coordination Polymers: Synthesis, Structural
Diversity and Catalytic Applications in Homo-coupling Reactions
a
Qiong Wu,‡a Yanbing Han,‡a Zhichao Shao,a Junxia Li,b and Hongwei Hou
*
Received 00th January 20xx,
Accepted 00th January 20xx
DOI: 10.1039/x0xx00000x
We have synthesized three new stable Fe(II) coordination polymers, {[Fe3(tttmb)4(OH)(NCS)5]2CH3OH·H2O}n (1),
{[Fe3(tttmb)4(NCS)6]·3H2O}n (2), {[Fe3(ttmb)2Cl6(H2O)6]·5H2O}n (3) (tttmb = 1,3,5-tris(triazole-1-ylmethyl)-2,4,6-trimethyl-
benzene) under the regulation of KSCN and solvents, and used the polymers as green heterogeneous catalysts in aryl
homo-coupling reactions. Catalytic experiments show that 1 and 3 exhibit high efficiency to aryl homo-coupling reactions
under air environment with the yield up to 80%. Crystal structure analysis reveals that 1 and 3 have coordinated water
molecules and OH-, which are easily removed from host materials during the reactions. As for 2, no unsaturated
coordination sites are generated during the reaction process. In addition, variable temperature magnetic susceptibilities of
1-3 proved that center metal of these polymers were bivalent and all of them exhibit weak antiferromagnetic effect.
www.rsc.org/
cross-coupling reactions, coordination polymers based on Ni(II)
and Cu(II) have already been applied in catalyzing coupling
Introduction
reactions.14-15 However, they have the drawbacks of toxic and not
economic-green. Therefore, Fe(II) coordination polymers are
needed as catalysts in coupling reactions. In fact, Fe(II) coordination
polymers catalysts can easily be separated from the substrate by
the magnetic field of the magnet, which have not been studied. The
"design" and excellent properties of Fe(II) coordination polymers
are the basis for determining possible catalytic properties.16 It is
obvious that the catalytic activity of Fe(II) coordination polymers
would depend heavily on the spatial configuration of the organic
ligands.17 1,2,4-triazole derivatives as ligands are important
candidates for constructing organic-inorganic skeletons, because
they can bind the coordination geometry of both imidazoles and
The efficient green synthesis of biphenyl compounds is pretty
significant because they were widely found in dyestuffs, medicine,
pesticide and natural products.1-3 Homo- and cross-coupling
reactions are frequently adopted in building carbon-carbon bonds,
especially in producing biphenyl compounds and heteroaromatic
analogues.4 Historically, the Ullmann reaction was the first efficient
method to prepare biphenyl compounds where copper is catalyst.
However, stoichiometric copper was used and the temperature was
over 200 °C in this reaction.5-6 These shortcomings promoted the
development of various mild methods depending on the use of
transition metal catalysts such as Fe, Pd, Ni, Pt, Rh to obtain
biphenyl compounds.7-9 Among them, Fe is the most “cost-
effective” for the character of non-toxic, cheaper, abundant and
environmentally friendly. Fe-catalyzed cross-coupling reactions
usually require the use of Grignard reagents, causing the reactions
to be moisture-sensitive and difficult to control.10 To optimize the
reaction conditions, Cheng and co-workers used halogenated
aromatic hydrocarbons and magnesium instead of Grignard
reagents to prepare biphenyl compounds, but the cyclic utilization
of Fe is almost nonexistent.11 Hence, the study of new stable
heterogeneous catalysts is still needed.
pyrazoles together, and exhibit
a strong and representative
property as bridging ligands between two metal ions. In this
bridging capacity, 1,2,4-triazole derivatives can exhibit great
coordination diversity.18 Meanwhile, Fe(II) irons as Lewis acid can
provide active sites for some organic synthesis requiring Lewis
acidity.19 Thus, the exploration of Fe(II) coordination polymers
catalysts for homo-coupling reaction based on 1,2,4-triazole
derivatives is of great significance.
Incited by the discussions above, we prepared three polymers,
Coordination polymers as burgeoning catalysts constructed from
organic ligands and metals have become the focus of the
researches.12 They have provided great promise as single sites or
cooperativity catalysts for C−C bonds formaꢀon, oxidaꢀons,
epoxidations, cyclization, and many other reactions.13 For C−C
namely, {[Fe3(tttmb)4(OH)(NCS)5]
·2CH3OH
·H2O}n (1), {[Fe3(tttmb)4-
(NCS)6] 3H2O}n (2), {[Fe3(ttmb)2Cl6(H2O)6]
·
·5H2O}n (3). The variable
temperature magnetic susceptibility tests of 1-3 manifested the
central metals are all Fe(II). All of them show high stability in
general organic solvents, and have been applied in catalyzing homo-
coupling reaction for the preparation of biphenyl compounds under
mild conditions. As the results, 1 and 3 exhibited predominant
catalytic properties to aryl homo-coupling reaction. The structural
features of 1 and 3 allow them to promote the progress of the
reaction. In addition, the influence of KSCN and solvents on the
preparation and configuration of polymers 1-3 were stated, and the
thermal stabilities of 1-3 were also investigated.
aThe College of Chemistry and Molecular Engineering, Zhengzhou University,
Zhengzhou, Henan, 450001, P. R. China
b Food and Drug Inspection Institute of Zhengzhou, Henan 450000, P. R. China
Electronic Supplementary Information (ESI) available: Crystallographic
†
parameters, PXRD, TGA, CCDC number: 1841130, 1841131 and 1841154. For ESI
and crystallographic data in CIF See DOI: 10.1039/x0xx00000x
‡These authors contributed equally to the work and should be considered cofirst
authors.
This journal is © The Royal Society of Chemistry 20xx
J. Name., 2013, 00, 1ꢀ3 | 1
Please do not adjust margins

Please do not adjust margins
Dalton Transactions
Page 2 of 7
View Article Online
DOI: 10.1039/C8DT01839A
COMMUNICATION
Journal Name
squares technique based on F2 with the SHELXL-97 crystallographic
software package.22 The H atoms were added geometrically and the
isotropic displacement parameters were refined using riding model.
The crystallographic data and structure refinement details of 1-3
are exhibited in Table S1 and S2(ESI†). CCDC reference numbers:
1841130, 1841131 and 1841154.
Experimental
General Information
All reagents and solvents were purchased in general commercial
channels without further purification. The water used in the
experiment is de-ionized water. 1,3,5-tris(triazole-1-ylmethyl)-2,4,6-
trimethylbenzene (tttmb) was synthesized with the modified
procedure according to the literature.20 Bruker-ALPHA
spectrophotometer was utilized to record infrared spectroscopy
(FT-IR) with KBr pellets in the scale of 400-4000 cm-1. Element
analyses of C, H, and N were conducted on FLASH EA 1112
elemental analyzer. Powder X-ray diffraction (PXRD) patterns were
carried out on the PANalytical X'Pert PRO diffractometer (Cu-Kα).
Thermogravimetric analyses (TGA) were measured on a Netzsch
STA 449C thermal analyzer at 10 °C per minute heating rate at room
temperature. 1H spectra were measured using Bruker Avance-400
spectrometers. Magnetic measurements were performed on SQUID
MPMS XL-7 instrument within 2-300 K scope.
Solvent Stability Experiment 1-3 were suspended in boiling
frequently used solvents (acetonitrile, DMF, chloroform and THF)
respectively for 48 hours. During this period, the samples were
taken out at intervals and supervised under optical microscopy.
Then the samples were filtered out, washed with the solvent and
dried spontaneously. Crystallographic parameters were detected by
Single-crystal X-ray diffraction.
General Steps for the Synthesis of Biaryl Compounds with 1-3 as
Catalysts Iodobenzene (0.5 mmol), magnesium strip (0.6 mmol) and
catalyst (0.05 mmol) were placed in 25 mL round bottom flask, then
put the anhydrous tetrahydrofuran (2 mL) to the flask quickly and
heated to reflux under dry air. After 8 h, the cool reaction solution
was filtered and washed three times with a small amount of ethyl
acetate. Then hydrochloric acid (0.5 N, 10 mL) was dropped into the
filtrate, the mixture was extracted with 3 × 10 mL's EtOAc. Then the
organic layers were washed by de-ionized water and dried
overnight with anhydrous Na2SO4, filtered and condensed to get the
crude products. Subsequently, the crude products were purified
with hexane using column chromatography. The pure products
were characterized by 1HNMR (400 MHz) (Table S3†).
Synthesis
{[Fe3(tttmb)4(OH)(NCS)5]·2CH3OH·H2O }n (1). tttmb 18.1 mg (0.05
mmol), FeCl2·4H2O 19.8 mg (0.1 mmol), KSCN 19.6 mg (0.2 mmol), 9
mL CH3OH and 1 mL de-ionized water were placed in a 25 mL
Teflon-lined stainless steel container, then the mixture was heated
at 160 °C for 72 h. After cooled to room temperature at the rate of
5 °C/h, colorless rod shaped crystals 1 were obtained in yield of 24%
(based on metal Fe). The elemental analysis data based on the
C79H95N41O4S5Fe3 (2009.54), calculated (%): C, 47.19; H, 4.72; N,
28.57. Found (%): C, 47.18; H, 4.75; N, 28.53. IR (KBr, cm-1): 3425(s),
2958(m), 1442(s), 1289(w), 1145(m), 880(m), 836(w), 703(w),
674(w), 636(w), 475(w).
Results and discussion
Crystal structure of {[Fe3(tttmb)4(OH)(NCS)5]·2CH3OH·H2O}n (1).
Single-crystal X-ray diffraction studies demonstrate that 1, which
belongs to monoclinic system with P21/c space group, is a 3D
framework. As shown in Fig. 1a, each asymmetric unit contains
three independent Fe(II) ions (occupying 0.5, 0.5, 0.5) and two
{[Fe3(tttmb)4(NCS)6]·3H2O}n (2). tttmb 18.1 mg (0.05 mmol),
FeCl2·4H2O 19.8 mg (0.1 mmol), KSCN 19.6 mg (0.2 mmol), 9 mL
CH3CN and 1 mL de-ionized water were placed in 25 mL Teflon-lined
stainless steel container, then the mixture was heated at 160 °C for
72 h. After cooled to room temperature at the rate of 5 °C/h,
colorless rod-shaped crystals 2 were acquired in yield of 68% (based
on metal Fe). Colorless rod shaped crystals 2 were acquired in yield
of 68% (based on metal Fe). The elemental analysis data for
C78H90N42O3S6Fe3 (2024.01), calculated (%): C, 46.28; H, 4.50; N,
29.07. Found (%): C, 46.25; H, 4.51; N, 29.06. IR (KBr, cm-1): 3510(s),
3172(m), 1988(s), 1421(s), 1255(m), 1099(m), 1120(s), 1011(m),
781(w), 661(w), 481(w).
{[Fe3(tttmb)2Cl6(H2O)6]·5H2O}n (3). The procedure is similar to 2,
except that the amount of the KSCN was reduced to 9.8 mg (0.1
mmol). Colorless rod shaped crystals 3 were gathered in yield of
30% (based on metal Fe). The elemental analysis data of
C
36H64N18O11Cl6Fe3 (1305.43): calculated (%): C, 33.12; H, 4.95; N,
19.32. Found (%): C, 33.14; H, 4.96; N, 19.34. IR (KBr, cm-1): 3121(m),
2022(s), 1522(s), 1273(m), 1211(m), 1124(s), 1054(m), 996(m),
776(w), 651(w ), 501(w).
Crystal Date Collection and Refinement
The data of 1-3 were collected on Rigaku Saturn 724 CCD diffraction
(Mo-Kα, λ=0.71073 Å) at 293 K. Absorption corrections were
applied by utilizing multi-scan program. The data were corrected for
Lorentz and polarization effects.21 The structures of 1-3 were
settled by direct methods and refined with a full-matrix least-
Fig.1 (a) View of coordination environments of Fe (II) in 1. (b) Propeller
structure constructed by the coordination of Fe1 and four ligands in 1. (c)
Ballꢀstick view of the 3D framework in 1. (d) Schematic representation of
topology network for 1.
2 | J. Name., 2012, 00, 1ꢀ3
This journal is © The Royal Society of Chemistry 20xx
Please do not adjust margins

Please do not adjust margins
Dalton Transactions
Page 3 of 7
View Article Online
DOI: 10.1039/C8DT01839A
Journal Name
COMMUNICATION
independent tttmb ligand. The Fe (II) ions locate in a slightly
distorted octahedral coordination configuration. The Fe1 is
surrounded by four N atoms from four different ligands (N9, N10,
N9#1, N10#1; the distance of Fe1-N: 2.1739(86)-2.1755(45) Å), one
N atom deriving from SCN- (N20, the distance of Fe1-N: 2.1894(120)
Å) and one O atom from the coordinated OH- (O1, the distance of
Fe1-O: 2.2892(137) Å. The bond angle around Fe1 varies from
87.084(180)° to 180.000 (1)°. Fe2 is a six-coordinated geometry
surrounded by six N atoms, in which four N atoms (N15, N15#2,
N6#3, N6#4, the distance of Fe2-N: 2.1675(97)-2.2623(64) Å) are
from four different ligands and the other two N atoms (N19, N19#2 ;
Fe2-N distance: 2.1641(83) Å) come from the two SCN-. The bond
angels of N-Fe-N fluctuate in the range of 84.626(249)°-
177.141(298)°. The coordination mode of Fe3 is very similar to that
of Fe2. There is nothing but the bond lengths and the bond angles
around Fe3 have slightly disparity. There are two different types of
ligands (namely, tttmb-I and tttmb-II) which both are symmetrical
cis-conformation, with three triazoles on the same side of central
benzene ring. Ndonor···N−Csp3···Csp3 torsion angles of tttmb-I are
129.544°, 104.627° and -13.73° while tttmb-II are 128.964°, 98.713°
and -18.85°. Interestingly, the four ligands around Fe1 connected to
the four sides formed an interesting propeller structure (Fig. 1b).
Such a structure forms a porous 3D structure by connecting the
other two kinds of Fe ions in space infinitely (Fig. 1c). Further
analysis from the viewpoint of topology structure show that each Fe
is 4-connection and each ligand connects three metals which can
simplified the ligands into 3-junction, thus 1 is a (3,4)-connected
network structure in topology, the symbol is (124.182)(3.122)4
(3.6.7)8(62.124)2 (Fig. 1d). In addition, two CH3OH molecules and one
water in 1 were removed by the SQUEEZE routine in PLATON.23 The
final molecular formula was determined by combing the single-
crystal structure, thermogravimetric analysis (TGA) and elemental
analysis.
Fig. 2 The ballꢀstick model of structural unit for 2
(Fig. 3c). Furthermore,
3 exhibits a supramolecular three-
dimensional framework as a result of π···π-stacking interactions
between the two parallel benzene rings whose face-to-face
distance is 3.9453 Å (Fig. 3d). Similar to 1, five water molecules in 3
were removed by the SQUEEZE routine in PLATON.
Effect of KSCN and Solvent on the Structure of 1-3. On the
aforementioned descriptions of structures, 1 and 2 were prepared
successfully under similar conditions except for adding different
solvent (methanol and acetonitrile). These solvent molecules could
influence the number of coordinated SCN-. For 1, all the
coordination sites are occupied by SCN-, ligand and OH-, while there
is no OH- was found in each asymmetric unit of 2. The reason may
be that the polarity of methanol is larger than that of acetonitrile,
which reduced the coordination ability of the SCN- with Fe(II) ions. If
the amount of KSCN was reduced, neither 1 nor 2 would be
obtained. Interestingly, when the amount of KSCN was reduced to
0.1 mmol, 3 was achieved as a sole product in the acetonitrile-
Crystal structure of {[Fe3(tttmb)4(NCS)6]·3H2O}n (2). Single-crystal
X-ray diffraction study declared that 2 crystallized in monoclinic
space group P21/c, whose spatial structure is very similar to 1. Its
asymmetric unit contains two independent tttmb ligands (namely,
tttmb-I and tttmb-II), three Fe(II) ions and six SCN-. As portrayed in
Fig. 2, tttmb-I and tttmb-II all exhibit cis-configuration. The six-
coordinated Fe1 is surrounded by four N atoms from four different
ligands and two N atoms deriving from SCN-, forming a lightly
distorted octahedron. The coordination modes of Fe2 and Fe3 are
as same as those of 1. Similarly, three water molecules in 2 were
also removed by the SQUEEZE routine in PLATON. Thus, no more
discussion would be detailed here.
Crystal structure of {[Fe3(tttmb)2Cl6(H2O)6]·5H2O}n (3). For 3, each
unsymmetrical structural unit contains 0.5 Fe, 1/3 ligands, one
coordination chlorine and one coordination water (Fig. 3a). The
Fe(II) ions have
a slightly distorted octahedral coordination
geometry, filled by two coordinated N from different ligands (N1,
N1#1, distance of Fe1-N: 2.1706(25) Å), two coordinated Cl-
(distance of Fe-Cl: 2.5158(12) Å), and two coordinated water
molecules (distance of Fe-O: 2.1273(19) Å). The bond angles around
Fe(II) range from 85.754(90)° to 180.000°. The tttmb ligand adopted
an absolute symmetric cis-configuration, forming a symmetric
configuration centred on the phenyl ring. The coordination mode
and configuration of N atoms on each triazole are the same as the
central Fe(II) ions and are absolutely symmetric. The tttmb ligands
and Fe(II) ions expand infinitely in space, generating a wavy 2D layer
(Fig. 3b) with hexagonal channel dimensions of 14.418 Å × 14.418 Å
Fig. 3 (a) View of coordination environments of Fe (II) of 3. (b) Ballꢀstick
view of 2D of 3 (along the bꢀaxis). (c) View of 2D layered structure of 3. (d)
3D structure diagram of 3 for π···πꢀstacking interactions.
water system. However the KSCN did not participate in the
coordination process, and acted as a template to take part in the
This journal is © The Royal Society of Chemistry 20xx
J. Name., 2013, 00, 1ꢀ3 | 3
Please do not adjust margins

Please do not adjust margins
Dalton Transactions
Page 4 of 7
View Article Online
DOI: 10.1039/C8DT01839A
COMMUNICATION
Journal Name
crystallization process. In addition, we replace the KSCN with KCl,
KBr, K2C2O4 H2O and KNO3, no crystal can be obtained.
·
2Ng2β2
exp −χ +4exp ꢀ−4χꢁ
ꢀ
ꢁ
χn=
×
ꢀ
ꢁ
KT
1+2 exp −χ +2exp ꢀ−4χꢁ
Study on PXRD and Stabilities of 1-3. The powder X-ray diffraction
tests were carried out at room temperature. The results indicated
that experimental data coincide with the corresponding theoretical
simulation data, which reveal that 1-3 are pure phase (Fig. S1†). To
get better insight into the catalytic properties of 1-3, we first
explored their stability in different solvents. Experimental results
indicated that 1-3 could keep the original morphology in boiling
CH3CN, DMF, CH2Cl2 and THF for 24 h, which can be confirmed by
single crystal XRD with the same crystallography parameters. In
boiling EtOH, 3 lost its crystalline state a few hours later, while 1
and 2 can maintain their original crystalline state for 24 h. 1 and 2
could exhibit more excellent stabilities in common solvents, which
may be ascribed to their dense structures and their stable 3D
framework without an obvious cavity. For 3, the big 2 D channels
make solvent molecules contact with crystals easily, especially polar
solvents. Then accelerate the dissolution of framework. The
thermal stabilities of 1-3 were explored by thermogravimetric
analysis (TGA). As shown in Fig. S2†, 1 shows the weight loss of
4.08% (theoretical 4.1%) for releasing of two methanol solvent
molecules and one water molecules in the temperature range of
45-270 °C, the main skeletons begins to collapse at 300 °C. For 2,
the weight loss of 2.79% (theoretical 2.7%) occurred at 48-275 °C,
which can attributed to the loss of three solvent water molecules.
The second step of weight loss began at 310 °C, due to the collapse
of the crystal skeleton. The TG curve of 3 reveals the first weight
loss of 7.1% (theoretical 6.9%) at the range of 50-290 °C, for the
losing of five water molecules. Then the framework began to
collapse when the temperature reaches to 300 °C (Fig. S2†).
6
4
2
ꢀ ꢁ ꢀ ꢁ
ꢀχ ꢁ ꢀ1−exp −χ ꢁ+ꢀ3χꢁꢀexp −χ −exp ꢀ−4χꢁꢁ
2
χ1= Ng β
×
ꢀχ = D/KTꢁ
ꢀ ꢁ
1+2 exp −χ +2exp ꢀ−4χꢁ
KT
χFe= ꢀχ∏+2χ1)/3
χFe
χm=
1
′
2ZJ
2
1−χFeꢀNg
）
2
β
data with Curie-Weiss law, following value are obtained, C = 4.40
cm3 K mol-1, θ = – 14.09 K, zJ’ = – 0.81 cm-1, g = 2.41 and D = – 11.5
cm-1.
Magnetic Properties of 1-3. The magnetic susceptibilities of 1-3
were measured at the temperature range of 2-300 K under the
magnetic field strength of 1 kOe. The diamagnetic fraction is
corrected by Pascal constant.24 The experimental χMT value of 1 is
3.95 cm3 K mol-1 at 300 K, which corresponds to the high-spin Fe(II).
As the temperature decreases, χMT shows a decreasing trend and
reaches to the minimum value of 0.40 cm3 K mol-1 at 2 K (Fig. 4a).
The results prove that there is antiferromagnetic effect between
Fe(II) irons.25 The χM-1-T curve is fitted on the basis of Curie-Weiss
law [1/χM = (T - θ)/C],26 C = 4.09 cm3 K mol-1 and θ = –15.9 K. The
negative value of θ proves extremely weak antiferromagnetic
interaction between Fe(II) ions. The analysis of the structure shows
that the two Fe(II) ions are far apart, so the interaction between
metals can be ignored directly, and the cause of anti-
ferromagnetism may result in the zero-field splitting of Fe(II). The
formula 1 below is utilized to analyze data, and the fitting results
are: zJ’ = – 0.48 cm-1, g = 2.07 and D = – 4.17 cm-1.
Fig. 4 The diagram of χMT versus T and χMꢀ1 versus T for
magnetic field strength of 1 kOe (a for , b for , c for ).
1ꢀ3 recorded at
1
2
3
The Catalytic Performance of 1-3. To explore the catalytic activities
of polymers 1-3, the polymers-catalyzed homo-coupling reactions
of iodobenzene with the presence of Mg were performed. As
shown in Table 1, 1 and 3 as catalysts can promote the catalytic
homo-coupling of iodobenzene with desired products in yields of
78% and 80%, whereas only trace products were found when 2
participates as a catalyst. The iodobenzene derivatives were also
employed as substrates to investigate the catalytic activities of 1
and 3 under the same condition (Table 1). According to these
results, we can deduce that the activity of these polymers in the
catalytic reaction of iodobenzene derivatives is almost the same as
the activity against iodobenzene. In addition, we tested the catalytic
properties of FeCl2 and FeCl3 as homogeneous catalysts catalyzed
iodobenzene under the same conditions for comparison. We found
FeCl2 was oxidized to form Fe(III) ions quickly with no product
The experimental χMT value of 2 (Fig. 4b) is 4.02 cm3 K mol-1 at 300 K,
and it drops to a minimum value of 0.99 cm3 K mol-1 at T = 2 K,
indicating the presence of high-spin Fe(II) and antiferromagnetic
interactions. 2 also obey the Curie-Weiss law with C = 3.50 cm3
K
mol-1 and θ = –11.08 K. The negative value of θ also indicates the
weak antiferromagnetic interactions among the Fe(II). This
phenomenon is likely caused by zero-field splitting of Fe(II). The plot
fitted according to the formula 1 lead to the following parameters:
zJ’ = – 0.17 cm-1, g = 1.98 and D = – 2.7 cm-1.
generation, and the substrate reacted entirely
6 hours later
(monitoring with TCL). The yields of homo-coupling reaction where
FeCl2 and FeCl3 were involved as catalysts are both about 40%. By
comparison, polymers 1 and 3 as heterogeneous catalysts have
For 3 (Fig. 4c), similar behavior was observed to 1 and 2. All of them
have weak antiferromagnetic interactions. Fitting the experimental
4 | J. Name., 2012, 00, 1ꢀ3
This journal is © The Royal Society of Chemistry 20xx
Please do not adjust margins

Please do not adjust margins
Dalton Transactions
Page 5 of 7
View Article Online
DOI: 10.1039/C8DT01839A
Journal Name
COMMUNICATION
higher efficiency than homogeneous catalyst FeCl3 under the same
reaction condition.
The high catalytic activity of
specific frameworks. Crystallographic structural analyses reveal that
1
and
3 can be attributed to their
each asymmetric unit of
1
has a coordinated OH- which is easy to
remove. Since the nucleophilic ability of OH- is weaker than I-, Fe(II)
as Lewis acid is prone to combine with more nucleophilic groups in
the catalytic process, where the I- from substrates replaced the site
of the coordinated OH- to form an intermediate. As for
3, the
presence of coordinated water is a crucial factor, because water
molecule is a fine leaving group.27 They may depart during the
catalytic reactions, leaving unsaturated Fe sites. Besides, 3 has a 2 D
channel for 14.418 Å × 14.418 Å. This big open channel can promote
the transportation of organic substrates and products. Thus the
substrates can be easily accessible to unsaturated sites. For
coordination sites are saturated and there are no groups easy to
2, the
Fig. 5 Catalytic cycling test results of
1
leave during the process of reaction, which made
catalytic activity.
2 showed a low
simulated patterns after reused four times (Fig. S3†), which shows
the frameworks did not collapse and decomposition at four runs
later. As for , the data of before and after the catalytic reaction
can't be well matched after 2 cycles, revealing that the skeleton
3
We also evaluated recycled and reused
reactions with 4b (Table 1). The polymers-catalysts
1
and
3
for the catalytic
and were
1
3
recovered by magnet's adsorption and filtering out from the
reactions, which make the separation more convenient and quickly.
During the separation, we transfer the reaction solution to a beaker
at first. Then take a sizeable magnet and place it on the bottom of
the beaker. Polymers- catalysts are all concentrated at the bottom
due to the magnetic field effect and do the filtration finally. Fig. 5
suggested that there is no obvious change in the yield of catalysts
after four reuses for 1. The PXRD pattern of 1 can closely match the
Table 1 Performance of Fe(II)-coordination polymers 1-3
as heterogeneous catalyst in biphenyl reactions.
Scheme 1 Proposed mechanism of biphenyl reaction by Fe(II)ꢀcoordination
polymers catalyzed.
began to collapses over two rounds.
The conceivable mechanism is proposed in Scheme 1 based on
previous results. First, the halogenated substrate forms the
Grignard Reagent intermediate with magnesium and then the
Entry
substrate
4a
catalyst
product
5a
Yield (%)
1
FeCl3
40
intermediate is activated by the catalyst (1, 3) to provide I. Next,
iodobenzene (derivatives) attacks the Fe(II) active site of I rapidly to
produce a diaryl-complex intermediate (II). Reductive elimination of
the homo-coupling forms desired products and regenerates the
2
1
78
3
2
trace
80
catalytically active Fe(II)-polymers (1, 3).
4
3
Conclusions
5
FeCl3
5b
60
Three Fe(II) coordination polymers were built triumphantly by
tttmb under the hydrothermal condition. We have demonstrated
6
4b
4c
1
75
7
3
78
that
1 and 3 were promising heterogeneous catalysts to activate
aryl homo-coupling reaction for stupendous advantages of
economy, efficient, environmentally friendly and easily separated.
8
FeCl3
50
Noticeably,
reduction in catalytic activity. Furthermore, the structural
diversities of indicate that the KSCN and the solvent act a
1 displayed high recyclability with no significant
9
1
3
5c
70
10
75
1-3
pivotal part in preparing polymers
configuration.
1-3 as well as the final
This journal is © The Royal Society of Chemistry 20xx
J. Name., 2013, 00, 1ꢀ3 | 5
Please do not adjust margins

Please do not adjust margins
Dalton Transactions
Page 6 of 7
View Article Online
DOI: 10.1039/C8DT01839A
COMMUNICATION
Journal Name
and J. P. Lang, Dalton Trans., 2015, 44, 130-137; (g) T. A.
Dwight, N. R. Rue, D. Charyk, R. Josselyn and B. DeBoef, Org.
Lett., 2007, 9, 3137-3139; (h) C. P. Li and M. Du, Inorg. Chem.
Acknowledgements
This work was financially supported by the National Natural Science
Foundation (No. 21671174) and the Natural Science Foundation of
Henan province (No. 182300410008).
Commun., 2011, 14, 502-513.
14 L. Liu, C. Huang, X. N. Xue, M. Li, H. W. Hou and Y. T. Fan,
Cryst. Growth Des., 2015, 15, 4507-4517.
15 L. Guo, C. Huang, L. Liu, Z. Shao, Y. Tong, H. W. Hou, and Y. T.
F, Cryst. Growth Des., 2016, 16, 4926–4933.
16 (a) N. C. Bruno, M. T. Tudge and S. L. Buchwald, Chem. Sci.,
2013, 4, 916-920; (b) M. Du, C. P. Li, C. S. Liu and S. M. Fang,
Coord. Chem. Rev., 2013, 257, 1282-1305; (c) S. C. Chen, Z. H.
Zhang, K. L. Huang, Q. Chen, M. Y. He, A. J. Cui and M. Du,
Notes and References
1
2
3
4
J. Hassan, M. Sevignon and C. Gozzi, Chem. Rev., 2002, 102,
1359-1470.
R. H. Thomson, The Chemistry of Natural Products, Blackie,
Glasgow, 1985.
P. Corbet. J, and G. Mignani, Chem. Rev., 2006, 106
2651−2710.
(a) Y. Yu and B. B. Yu., Appl. Organomet. Chem., 2008, 22
Cryst. Growth Des., 2008,
17 (a) Y. Y. Jia, H. J. Li, B. Zhao, Q. Q. Guo, H. W. Hou and Y. T.
Fan, Eur. J. Inorg. Chem., 2013, , 438-445; (b) T. Li, F. L.
8, 3437-3445.
3
,
Wang, S. T. Wu, X. H. Huang, S. M. Chen and C. C. Huang,
Cryst. Growth Des., 2013, 13, 3271-3274; (c) Y. Han, H. Xu, Y.
Y. Liu, H. J. Li, H. W. Hou, Y. T. Fan and S. R. Batten, Chem.
Eur. J., 2012, 18, 13954-13958; (d) Q. Q. Guo, C. Y. Xu, B.
Zhao, Y. Y. Jia, H. W. Hou and Y. T. Fan, Cryst. Growth Des.,
2012, 12, 5439-5446; (e) V. A. Colombo, S. Galli, H. J. Choi, G.
D. Han, A. Maspero, G. Palmisano, N. Masciocchi and J. R.
,
15−18; (b) D. W. Tan, H. X. Li, D. L. Zhu, H. Y. Li, D. J. Young J.
L. Yao and J. P. Lang, Org. Lett., 2018, 20, 608–611; (c) L. M.
Zhang, H. Y. Li, H. Xi. Li, D. J. Young, Y. Wang and J. P. Lang,
Inorg. Chem., 2017, 56, 11230–11243; (d) L. Y. Xu, C. Y. Liu, S.
Y. Liu, Z. G. Ren, D. J. Young and J. P. Lang, Tetrahedron.,
2017, 73, 3125-3132; (e) J. Y. Xue, J. C. Li, H. X. Li, H. Y. Li, J. P.
Lang, Tetrahedron., 2016, 72, 7014-7020; (f) T. Y. Feng, H. X.
Li, D. J. Young and J. P. Lang, J. Org. Chem., 2017, 82, 4113–
4120.
Long, Chem. Sci., 2011, 2, 1311-1319; (f) L. Zhang, Y. J. Lin, Z.
H. Li and G. X. Jin, J. Am. Chem. Soc., 2015, 137, 13670-13678.
18 (a) J. G. Haasnoot, Coord. Chem. Rev., 2000, 200, 131-185; (b)
Y. J. Mu, J. H. Fu, Y. J. Song, Z. Li, H. W. Hou and Y. T. Fan,
Cryst. Growth Des., 2011, 11, 2183–2193; (c) C. Y. Xu, L. K. Li,
Y. P. Wang, Q. Q. Guo, X. J. Wang, H. W. Hou and Y. T. Fan,
Cryst. Growth Des., 2011, 11, 4667–4675; (d) D. S. Li, Y. P.
Wu, J. Zhao, J. Zhang and J. Y. Lu, Coord. Chem. Rev., 2014,
261, 1-27;
19 (a) Z. Q. Xu, W. Meng, H. J. Li, H. W. Hou and Y. T. Fan, Inorg.
Chem., 2014, 53, 3260-3262; (b) S. Kobayashi, S. Nagayama
and T. Busujima, J. Am. Chem. Soc., 1998, 120, 8287-8288.
20 H. J. Li , X. Wang, Y. Y. Jia, B. Zhao, R. Ding, H. W. Hou and Y.
T. Fan, CrystEngComm., 2012, 14, 5155-5157.
5
6
7
C. Qi, X. Sun, and C. Lu, J. Organomet. Chem., 2009, 694,
2912-2916.
J. Hassan, M. Sevignon, C. Gozzi, E. Schulz and M. Lemaire,
Chem. Rev., 2002, 102, 1359−1469.
(a) S. L. Daifuku, J. L Kneebone, B. E. Snyder, and M. L.
Neidig, J. Am. Chem. Soc., 2015, 137, 11432-11444; (b) C.
Gosmini, J. M. Bégouin and A.Moncomble, Chem. Commun.,
2008, 28, 3221-3233; (c) L. Wang, Y. Zhang, L. Liu and Y.
Wang, J. Org. Chem., 2006, 71, 1284-1287.
8
9
(a) D. Alberico, M. E. Scott and M. Lautens, Chem. Rev., 2007,
107. 174-238; (b) A. Moncomble, P. L. Floch and C. Gosmini,
Chem. Eur. J., 2009, 15, 4770-4774; (c) J. Yamaguchi, K. Muto
and K. Itami, Eur. J. Org. Chem., 2013, 1, 19-30.
J. Yin, M. P. Rainka, X. X. Zhang and S. L. Buchwald, J. Am.
Chem. Soc., 2002, 124, 1162-1163.
21 C. J. F. Böttcher, O. C. van Belle and P. Bordewijk, Theory of
electric polarization. Elsevier Science Ltd. 1978.
22 G. M. Sheldrick SHELXL-97; Program for crystal-structure
refinement. University of Gottingen, Germany, 1997.
23 A. L. Spek, Implemented as the PLATON Procedure,
a
Multipurpose Crystallographic Tool, Utrecht University,
Utrecht, The Netherlands, 1998.
10 (a) C. Bolm, J. Legros, J. Le Paih and Z. Lorenzp, Chem. Rev.,
2004, 104, 6217-6254; (b) A. FMrstner, A. Leitner, M.
MOndez and H. Krause, J. Am. Chem. Soc., 2002, 124, 13856-
13863; (c) B. Scheiper, M. Bonnekessel, H. Krause, A.
FMrstner, J. Org . Chem., 2004, 69, 3943-3949.
24 E. König, Magnetic Properties of Coordination and
Organometallic Transition Metal Compounds. Berlin, 1966.
25 (a) S. Wöhlert, T. Runčevski, R. E. Dinnebier, S. G. Ebbinghaus
and C. Näther, Cryst. Growth Des., 2014, 14, 1902-1913; (b) T.
Wang, C. L. Zhang, Z. M. Ju and H. G. Zheng, Dalton Trans.,
2015, 44, 6926-6935; (c) C. S. Hawes, N. F. Chilton, B.
Moubaraki, G. P. Knowles, A. L. Chaffee, K. S. Murray, and R.
B. Stuart, Dalton Trans., 2015, 44, 17494-17507.
26 N. A. Pertsev, A. G. Zembilgotov, S. Hoffmann, R. Waser and
A. K. Tagantsev, J. Appl. Phys., 1999, 85, 1698-1701.
27 M. J. Liu, K. Gao, Y. R. Fan, X. Q. Guo, J. Wu, X. R. Meng and
H.W. Hou, Chem. Eur. J., 2018, 24, 1416-1424.
11 X. Xu, D. Cheng and W. Pei. J. Org. Chem., 2006, 71, 6637-
6639.
12 (a) C. Y. Xu, Q. Q. Guo, X. J. Wang, H. W. Hou and Y. T. Fan,
Cryst. Growth Des., 2011, 11, 1869–1879; (b) X. l. Wang, M. J.
Liu, H. Y. Fan, J. Wu, C. Huang, and H. W. Hou, Inorg. Chem.,
2017, 56, 13329-13336; (c) C. Huang, X. Han and Z. Shao,
Inorg. Chem., 2017, 56, 4874-4884; (d) J. P. Li, B. Li, M. Pan, B.
Liu, J. Cheng, R. Li, X. Gao, S. M. Wang, H. W. Hou, and Z. Y.
Liu, Cryst. Growth. Des., 2017, 17, 2975-2986; (e) B. B. Guo, Y.
J. Lin and G. X. Jin, Dalton Trans., 2017, 46, 8190-8197; (f) H.
Li, Z. J. Yao, D. Liu and G. X. Jin, Coord. Chem. Rev., 2015, 293
139-157.
,
13 (a) Y. P. Wu, G. W. Xu, W. W. Dong, J. Zhao, D. S. Li, J. Zhang
and X. H. Bu, Inorg. Chem., 2017, 56, 1402-1411 (b) L. B. Sun,
X. Q. Liu and H. C. Zhou, Chem. Soc. Rev., 2015, 44, 5092-
5147; (c) D. Farrusseng, S. Aguado and C. Pinel, Angew. Chem.
Int. Ed., 2009, 48, 7502-7513; (d) D. Dang, P. Wu, C. He and C.
Duan, J. Am. Chem. Soc., 2010, 132, 14321-14323. (e) Y. P.
Wu, W. Zhou, J. Zhao, W. W. Dong, Y. Q. Lan, D. S. Li, C. H.
Sun, X. H. Bu, Angew. Chem. Int. Ed., 2017, 56, 13001-13005
(f) Q. Liu, Z. G. Ren, L. Deng, W. H. Zhang, X. Zhao, Z. R. Sun
6 | J. Name., 2012, 00, 1ꢀ3
This journal is © The Royal Society of Chemistry 20xx
Please do not adjust margins

Page 7 of 7
Dalton Transactions
View Article Online
DOI: 10.1039/C8DT01839A
Stable Fe(II)-Based Coordination Polymers: Synthesis, Structural
Diversity and Catalytic Applications in Homo-coupling Reactions
,
Qiong Wu,a Yanbing Han, a Zhichao Shao, a Junxia Li,b and Hongwei Hou a
*
Three new stable Fe(II)-coordination polymers have been synthesized,
and successfully catalyzed the homo-coupling reaction in
“cost-effective” manner.
a