Supramolecular assembly under the control of the chelating ligand for the MnII/bridging ligands/3-sulfobenzoate system and catalytic properties for the disproportionation of hydrogen peroxide

Article abstract of DOI:10.1039/b9nj00428a

Six Mn^II 3-sulfobenzoate complexes with neutral ligands, [Mn(4,4′-bipy)₂(H₂O)₄](3-sb) ·3H₂O (1), {[Mn(3-sb)(bpe)_1.5(H₂O) ₂](bpe)_0.5·H₂O}_n

Full text of DOI:10.1039/b9nj00428a

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PAPER
www.rsc.org/njc | New Journal of Chemistry
Supramolecular assembly under the control of the chelating ligand for
the MnII/bridging ligands/3-sulfobenzoate system and catalytic properties
for the disproportionation of hydrogen peroxidewz
Xiao-He Miao and Long-Guan Zhu*
Received (in Montpellier, France) 27th August 2009, Accepted 17th November 2009
DOI: 10.1039/b9nj00428a
Six MnII 3-sulfobenzoate complexes with neutral ligands, [Mn(4,40-bipy)2(H2O)4](3-sb)ꢀ3H2O (1),
{[Mn(3-sb)(bpe)1.5(H2O)2](bpe)0.5ꢀH2O}n (2), [Mn(3-sb)(phen)(H2O)3](4,40-bipy)ꢀH2O (3),
[Mn2(3-sb)2(phen)2 (4,40-bipy)(H2O)4] (4), [Mn(3-sb)(phen)2(H2O)] (bpe)0.5ꢀ4H2O (5), and
[Mn(3-sb)(phen)2(H2O)](bpe)0.5ꢀH2O (6) [where 3-sb is 3-sulfobenzoate, 4,40-bipy is
4,40-bipyridine, bpe is 1,2-bis(4-pyridine)ethylene, and phen is 1,10-phenanthroline],
were synthesized and characterized by several modern analytic methods. The molecular
structures for the six complexes are monomers for complexes 3, 5, and 6, cation–anion
species for complex 1, dimer for complex 4, and 1-D polymer for complex 2. The phen
ligands in complexes 3 and 4 generate some effects on the hydrogen-bonding network, p–p
interactions, and supramolecular assembly. TG analysis showed that desolvated complexes
containing 4,40-bipy are less stable than those of complexes containing bpe ligands.
The emission strength order is 1 4 5 4 6 4 3 4 2 4 4, while the UV-vis absorption strengths
are 4 4 3 4 1 for complexes containing 4,40-bipy, and 5 4 6 4 2 for bpe metal complexes.
The catalytic experiments showed that these six complexes are catalytically active for the
disproportionation of H2O2 in the presence of imidazole and complex 3 has the best catalytic
activity.
system with neutral N-donor ligands, [Mn(4,40-bipy)2(H2O)4]-
Introduction
(3-sb)ꢀ3H2O (1), {[Mn(3-sb)(bpe)1.5(H2O)2](bpe)0.5ꢀH2O}n (2),
Recently, 4,40-bipyridine (4,40-bipy) and 1,2-bis(4-pyridine)
[Mn(3-sb)(phen)(H2O)3](4,40-bipy)ꢀH2O (3), [Mn2(3-sb)2(phen)2-
ethylene (bpe) ligands have widely been used as polymeric
(4,40-bipy)(H2O)4] (4), [Mn(3-sb)(phen)2(H2O)](bpe)0.5ꢀ4H2O (5),
linkers for constructing fascinating coordination polymers in
the field of potential functional materials.1–5 The 4,40-bipy or
and [Mn(3-sb)(phen)2(H2O)](bpe)0.5ꢀH2O (6).z
bpe ligands can also exhibit monodentate, dimeric linker or
non-coordinating modes,6–8 although they are relatively
Results and discussion
sparse. In previous studies, the 4,40-bipy or bpe ligands in
sulfobenzoate transition metal complexes gave novel coordination
modes.9–13 These studies focused on the ternary complexes
with one neutral ligand. The coordination of neutral ligands
with metal centers can largely change the coordination
environments, resulting in the tuning of the properties. Therefore,
we introduced the chelating ligand, 1,10-phenanthroline
(phen), into the MnII/bridging ligands/sulfobenzoate system
to investigate the influence of the mixed neutral ligands on the
diverse topology and supramolecular assembly. On the other
hand, MnII complexes have shown that they can act as
catalysts in several reactions, such as epoxidation,14 oxidative
aromatization,15 and oxidative decarboxylation.16 Herein, we
present the syntheses, crystal structures, and catalytic activity
of six complexes based on the MnII/3-sulfobenzoate (3-sb)
Synthesis
Ternary complexes 1 and 2 showed that the 4,40-bipy or bpe
can act as a terminal or dimeric bridge linker; such coordination
modes have been reported in our lab in the MnII/4-sb/4,40-bipy
system.9a The introduction of the second neutral ligand, phen,
into the MnII/3-sb/4,40-bipy or MnII/3-sb/bpe system can
influence the coordination modes of 3-sb, 4,40-bipy or bpe.
The diverse coordination modes provide different and abundant
supramolecular building blocks. Therefore complexes 3–6
were synthesized by using a two-step strategy.
The different synthetic conditions for complexes 3 and 4 are
that reflux was used for synthesizing complex 3 while hydro-
thermal conditions were used for synthesizing complex 4.
Furthermore, the mixed solvents of H2O–C2H5OH–DMF
were used in the synthesis of complex 3, while solvents of
water and DMF were used in the synthesis of complex 4. The
synthetic methods and conditions for complexes 5 and 6 are
similar to those in the syntheses of complexes 3 and 4,
respectively.
Department of Chemistry, Zhejiang University, Hangzhou 310027,
People’s Republic of China. E-mail: chezlg@zju.edu.cn;
Fax: 86-571-87951895; Tel: 86-571-87963867
w This article is part of a themed issue on Coordination polymers:
structure and function.
All these complexes are soluble in methanol and DMSO,
but insoluble in H2O, acetonitrile, and CH2Cl2.
z CCDC reference numbers 745965–745970. For crystallographic data
in CIF or other electronic format see DOI: 10.1039/b9nj00428a
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Descriptions of crystal structures
The anions and lattice water molecules also form 2-D hydrogen-
bonding layers (Fig. 3). The whole molecular structure is a 3-D
[Mn(4,40-bipy)2(H2O)4](3-sb)ꢀ3H2O(1). The X-ray analysis
revealed that complex 1 is a cation–anion species consisting of
a [Mn(4,40-bipy)2(H2O)4]2+ cation, a 3-sb2ꢂ anion, and lattice
water molecules (Fig. 1 and Table 1). There are two kinds of
metal environments but with similar geometrical parameters in
complex 1 and these Mn ions lie on inversion centres. Each
metal center is six-coordinated by four O atoms from four
water molecules and two N donors from two 4,40-bipy ligands.
All observed Mn–O and Mn–N distances in 1 are similar to
those reported in ref. 9a. The motif [Mn(4,40-bipy)2(H2O)4]
has been found in several papers,5,17 in which the 4,40-bipy acts
as a terminal ligand, monodentate mode. The pyridine rings of
the 4,40-bipy are not coplanar, with the dihedral angles
of 19.29(6)1 for Mn1 motif and 23.97(6)1 for Mn2 motif,
respectively. The [Mn(4,40-bipy)2(H2O)4] motif is a good
hydrogen-bonding donor or acceptor, in which not only the
water molecules but also the 4,40-bipy ligands are capable
of forming hydrogen-bonding interactions. The cations,
[Mn(4,40-bipy)2(H2O)4]2+, form 2-D hydrogen-bonding layers
by hydrogen bonds between monodentate 4,40-bipy ligands
and coordinated water molecules (Fig. 2). Within the 2-D
hydrogen-bonding layers, p–p interactions between 4,40-bipy
ligands occur with the centroid to centroid distances ranging
from 3.570(2) A to 3.784(2) A.
Table 1 Selected bond lengths (A) and angles (1) in complex 1
Mn1–O1
Mn1–N1
Mn2–O4
O1–Mn1–O2
O2–Mn1–N1
O3–Mn2–N3
2.251(3)
2.171(3)
2.139(3)
88.69(13)
88.78(12)
94.46(14)
Mn1–O2
Mn2–O3
Mn2–N3
O1–Mn1–N1
O3–Mn2–O4
O4–Mn2–N3
2.177(3)
2.299(3)
2.180(3)
87.44(12)
90.42(15)
90.42(15)
Fig. 2 View of 2-D hydrogen-bonding layer formed by cations in
complex 1.
Fig. 1 View of the molecular structure of complex 1. The thermal ellipsoids are drawn at 40% probability. Symmetry codes: i = ꢂx, ꢂy, ꢂz;
ii = 1 ꢂ x, ꢂy, ꢂz.
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architecture assembled by hydrogen bonds and p–p interac-
tions (Fig. 4).
(Fig. 5 and Table 2). The metal center geometry is defined by six
atoms forming a distorted octahedron. The 3-sb ligand bridges
two MnII centers through two carboxyl oxygen atoms, while the
sulfonate group is non-coordinating. The bpe ligands in complex
2 exhibit three coordination or existing modes, non-coordinating
as a free ligand, dimeric bridge, monodentate and two bpe
ligands (the bpe containing N3 and N4, respectively) lie about
the inversion centres. Two pyridine rings in each bpe are nearly
coplanar. The dimeric bridge mode of the bpe and the bridge
coordination of the 3-sb result in the 1-D molecular structure
(Fig. 6). The [Mn(3-sb)(bpe)1.5(H2O)2] units assemble into a 2-D
hydrogen-bonding layer by monodentate bpe and coordinated
water molecules (Fig. 7).
{[Mn(3-sb)(bpe)1.5(H2O)2](bpe)0.5ꢀH2O}n (2). Each asymmetry
unit of complex 2 contains one [Mn(3-sb)(bpe)1.5(H2O)2] unit,
half an uncoordinated bpe ligand, and one lattice water molecule
The [Mn(3-sb)(bpe)1.5(H2O)2] units and lattice water
molecules form a 3-D hydrogen-bonding architecture with
a 334.2 A3 hole, therefore the free ligands can occupy these
holes (Fig. 8). The weak p–p interactions occur between
dimeric linking bpe and monodentate bpe with the centroid-
to-centroid distance of 3.914(3) A, and between non-
coordinating bpe ligands with the centroid-to-centroid distance
of 3.891(3) A.
[Mn(3-sb)(phen)(H2O)3](4,40-bipy)ꢀH2O (3). Each repeat
unit of complex 3 consists of one [Mn(phen)(3-sb)(H2O)3]
Fig. 3 View of 2-D layer formed by the anions and lattice water
molecules in complex 1.
Table 2 Selected bond lengths (A) and angles (1) in complex 2
Mn1–O1
Mn1–O6
Mn1–N1
2.106(2)
2.262(2)
2.286(3)
112.14(9)
169.65(9)
85.39(10)
78.10(9)
90.26(10)
95.70(9)
90.03(11)
173.41(10)
Mn1–O2i
Mn1–O7
Mn1–N3
O1–Mn1–O6
O1–Mn1–N1
O2i–Mn1–O6
O2i–Mn1–N1
O6–Mn1–O7
O6–Mn1–N3
O7–Mn1–N3
2.133(2)
2.181(2)
2.254(3)
89.51(9)
88.04(10)
157.08(9)
92.61(10)
80.56(9)
83.84(9)
96.36(11)
O1–Mn1–O2i
O1–Mn1–O7
O1–Mn1–N3
O2i–Mn1–O7
O2i–Mn1–N3
O6–Mn1–N1
O7–Mn1–N1
N1–Mn1–N3
Symmetry code, i: 1 ꢂ x, 2 ꢂ y, 1 ꢂ z.
Fig. 4 View of the 3-D hydrogen-bonding architecture for complex 1.
Fig. 5 View of the molecular structure of complex 2. The thermal ellipsoids are drawn at 40% probability. Symmetry codes: i = 2 ꢂ x, 1 ꢂ y,
2 ꢂ z; ii = 2 ꢂ x, 2 ꢂ y, 2 ꢂ z; iii = 1 ꢂ x, 2 ꢂ y, 1 ꢂ z.
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Fig. 6 View of the 1-D chain formed by [Mn(3-sb)(bpe)1.5(H2O)2] units in complex 2.
Fig. 7 View of the 2-D hydrogen-bonding layer formed by [Mn(3-sb)(bpe)1.5(H2O)2] units in complex 2.
hydrogen-bonding layer of [Mn(3-sb)(phen)(H2O)3] units hold
together into a 3-D architecture by lattice water molecules and
4,40-bipy ligands (Fig. 11). Within the 3-D network, p–p inter-
actions only between phen and bpe ligands with the centroid-to-
centroid distances ranging from 3.625(2) A to 3.7018(19) A are
observed.
[Mn2(3-sb)2(phen)2(4,40-bipy)(H2O)4] (4). The molecular
structure of complex 4 is a dimer. The geometry of each MnII
can be described as a distorted octahedron completed by three
N donors from one phen and one 4,40-bipy and three O atoms
from one 3-sb and two water molecules (Fig. 12 and Table 4).
The 4,40-bipy lies about an inversion centre and bridges two
MnII centers as a dimeric linker. Pyridine rings of each
4,40-bipy are wholly coplanar. The Mnꢀ ꢀ ꢀMn separation
by the 4,40-bipy ligand is 11.618 A. The inter-molecular
hydrogen-bonding architecture is a 3-D network (Fig. 13), in
which neighboring dimeric molecules contain p–p interactions
only between phen ligands with the centroid-to-centroid
distance of 3.6432(18) A.
Fig. 8 View of the 3-D host–guest architecture for complex 2.
The stacked bpe ligands occupy the 3-D holes.
unit, one non-coordinating 4,40-bipy, and one lattice water
molecule. Each MnII center is coordinated by six coordination
donors, two N donors from one phen, and four O atoms from
three water molecules and one 3-sb ligand (Fig. 9 and Table 3).
The 3-sb ligand is monodentately coordinated to the MnII center
by the carboxyl group. The 4,40-bipy ligand is non-coordinating,
but forms hydrogen bonds with lattice water molecules and
coordinated water molecules. The [Mn(3-sb)(phen)(H2O)3]
units form a 2-D hydrogen-bonding layer (Fig. 10). The 2-D
[Mn(3-sb)(phen)2(H2O)](bpe)0.5ꢀ4H2O (5). Complex 5 is
made up of one [Mn(3-sb)(phen)2(H2O)] motif, half a free
bpe which lies about an inversion centre and four lattice water
molecules (Fig. 14 and Table 5). Each MnII center is
six-coordinated by four N donors from two phen ligands
and two O atoms from one 3-sb and one water molecule.
Two phen ligands are nearly perpendicular to each other, with
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Fig. 11 View of the 3-D hydrogen-bonding network for complex 3.
The [Mn(3-sb)(phen)2(H2O)] units form a 1-D hydrogen-
bonding chain through the hydrogen bonds between the
coordinated water molecule and sulfonate group (Fig. 15).
The lattice water molecules and free bpe ligands form 2-D
hydrogen-bonding layers (Fig. 16). The whole hydrogen-bonding
network is a 3-D architecture (Fig. 17).
There are strong p–p interactions between phen ligands, and
between phen and bpe ligands with the centroid-to-centroid
distances ranging from 3.569(2) A to 3.990(3) A.
Fig. 9 View of the molecular structure of complex 3. The thermal
[Mn(3-sb)(phen)2(H2O)](bpe)0.5ꢀH2O (6). The structure of
complex 6 is similar to that of complex 5, but they have
different lattice water molecules (Fig. 18 and Table 6). The
free bpe ligand lies about an inversion centre. Thus the
hydrogen-bonding assembly and p–p interactions are different
in complexes 5 and 6.
ellipsoids are drawn at 30% probability.
Table 3 Selected bond lengths (A) and angles (1) in complex 3
Mn1–O1
Mn1–O7
Mn1–N1
2.1311(18)
2.149(2)
2.291(2)
86.90(7)
92.73(8)
92.45(8)
179.41(8)
92.72(8)
97.54(8)
95.08(8)
72.87(8)
Mn1–O6
Mn1–O8
Mn1–N2
O1–Mn1–O7
O1–Mn1–N1
O6–Mn1–O7
O6–Mn1–N1
O7–Mn1–O8
O7–Mn1–N2
O8–Mn1–N2
2.1924(18)
2.1661(19)
2.266(2)
97.69(9)
162.91(8)
90.86(9)
85.15(7)
89.65(8)
169.41(9)
86.83(8)
The units [Mn(3-sb)(phen)2(H2O)] in complex 6 form
hydrogen-bonding chains similar to those in complex 5. In
complex 5, the bpe forms hydrogen bonds, while in complex 6,
the bpe does not form any hydrogen bonds.
O1–Mn1–O6
O1–Mn1–O8
O1–Mn1–N2
O6–Mn1–O8
O6–Mn1–N2
O7–Mn1–N1
O8–Mn1–N1
N1–Mn1–N2
The hydrogen-bonding structure of complex 6 is a 1-D chain
(Fig. 19), which is very different from that of complex 5. There
are abundant p–p interactions in complex 6 between phen
ligands, and between phen and bpe ligands with the centroid-
to-centroid distances ranging from 3.5141(14) A to 3.8864(18) A.
Influence of phen on supramolecular assembly
The phen ligand coordinates to the metal center in a chelating
mode, which reduces the coordination sites around the metal
center; therefore the coordination of the phen can influence the
molecular structure, hydrogen-bonding forming ability, and
supramolecular assembly. Complexes 1 and 2 contain one
neutral ligand, 4,40-bipy or bpe, respectively, and the four
complexes contain two neutral ligands, in which one of the
neutral ligands is the phen. The 4,40-bipy ligands exhibit a
monodentate coordination mode and hydrogen-bonding
forming ability in complex 1, a free ligand but a hydrogen-
bonding donor in complex 3, and a dimeric linker in complex
4. The bpe ligands show three modes in complex 2 (dimeric
linker, monodentate, and free ligand), a free ligand as a
hydrogen-bonding donor in complex 5, and a free ligand without
hydrogen-bonding forming ability in complex 6. The different
Fig. 10 View of the 2-D hydrogen-bonding layer formed by
[Mn(3-sb)(phen)(H2O)3] units in complex 3.
a dihedral angle of 82.7(1)1 for rings C16–C19/C23–C24 and
C5–C7/ C11–C12. The pyridine rings of the free bpe ligand are
completely coplanar.
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Fig. 12 View of the molecular structure for complex 4. The thermal ellipsoids are drawn at 30% probability. Symmetry code: i = ꢂx, 1 ꢂ y, 1 ꢂ z.
Table 4 Selected bond lengths (A) and angles (1) in complex 4
Mn1–O1
Mn1–O7
Mn1–N2
2.1143(16)
2.2001(19)
2.269(2)
171.74(7)
86.87(7)
87.87(7)
97.26(7)
84.49(7)
92.35(7)
72.81(7)
167.06(7)
Mn1–O6
Mn1–N1
Mn1–N3
O1–Mn1–O7
O1–Mn1–N2
O6–Mn1–O7
O6–Mn1–N2
O7–Mn1–N1
O7–Mn1–N3
N1–Mn1–N3
2.1694(18)
2.281(2)
2.267(2)
89.51(7)
100.43(7)
88.43(8)
87.65(7)
163.77(7)
97.68(7)
97.99(7)
O1–Mn1–O6
O1–Mn1–N1
O1–Mn1–N3
O6–Mn1–N1
O6–Mn1–N3
O7–Mn1–N2
N1–Mn1–N2
N2–Mn1–N3
coordination modes for 4,40-bipy in complexes 3 and 4, and
for bpe in complexes 5 and 6 compared with complexes 1 and 2
show that the phen ligands can adjust the coordination
environments. The number of water molecules around the
metal centers in 4,4-bipy complexes 3–4 and bpe complexes
5–6 are distinctly less than those corresponding 4,40-bipy and
bpe complexes 1 and 2, respectively. Therefore, the introduction
of the phen into the ternary metal systems largely changes the
supramolecular assembles, resulting in the diverse topologies
and different properties.
Fig. 13 View of 3-D hydrogen-bonding network for complex 4.
decomposed at 172 1C. For complex 3, the weight loss started at
73 1C and ended at 150 1C with the weight loss of 11.61%
(calculated 10.86%). Complex 3 decomposed at 156 1C. Complex
4 lost water molecules from room temperature to 125 1C, with
the weight loss of 6.47% (calculated 6.56%), and began to
decompose at 137 1C. Complex 5 released water molecules from
room temperature to 112 1C with the weight loss of 12.34%
(calculated 11.28%). Complex 5 decomposed at 168 1C.
Two-step release of lattice and coordinated water molecules were
obviously observed from 70 1C to 141 1C with the weight loss of
5.41% (calculated 4.85%), and the complex 6 decomposed at
170 1C. For these six complexes, the residues are MnO2 after
550 1C. To summarize, the TG curves showed that desolvated
complexes 2, 5, and 6 are more stable than the others, indicating
metal complexes containing 4,40-bipy are less stable.
Thermal stability studies
The thermal decomposition behaviors of 1–6 were investigated
in static air atmosphere from ambient to 800 1C. For the TG
curve of complex 1 the first stage of weight loss occurred
between 35 1C and 139 1C, corresponding to the removal of
three lattice water molecules with the weight loss of 8.59%
(calculated 8.96%). Further decomposition took place at
152 1C. Complex 2 lost water molecules from 61 to 146 1C
with the weight loss of 8.14% (calculated 8.02%). Complex 2
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Fig. 14 View of the molecular structure for complex 5. The thermal ellipsoids are drawn at 30% probability. Symmetry code: i = 1 ꢂ x, ꢂy, 1 ꢂ z.
Lattice water molecules are omitted for clarity.
Table 5 Selected bond lengths (A) and angles (1) in complex 5
Mn1–O1
Mn1–N1
Mn1–N3
2.118(3)
2.276(3)
2.282(3)
Mn1–O6
Mn1–N2
Mn1–N4
2.148(3)
2.279(3)
2.272(3)
O1–Mn1–O6
O1–Mn1–N2
O1–Mn1–N4
O6–Mn1–N2
O6–Mn1–N4
N1–Mn1–N3
N2–Mn1–N3
N3–Mn1–N4
89.66(11)
162.40(11)
105.11(10)
87.91(12)
94.10(13)
90.61(12)
97.13(11)
72.80(12)
O1–Mn1–N1
O1–Mn1–N3
O6–Mn1–N1
O6–Mn1–N3
N1–Mn1–N2
N1–Mn1–N4
N2–Mn1–N4
91.07(11)
89.31(10)
103.28(14)
166.09(14)
72.57(12)
156.36(12)
92.45(11)
Fig. 16 View of the 2-D hydrogen-bonding layer formed by bpe and
lattice water molecules in 5.
is 1 4 5 4 6 4 3 4 2 4 4. Therefore, in the 4,40-bipy metal
system the ternary metal complex, 1, is strongest, while in the
bpe metal system the ternary metal complex, 2, is weakest.
Fig. 15 View of the 1-D chain formed by [Mn(3-sb)(phen)2(H2O)]
units in complex 5.
Absorption spectra
These complexes have more intensive absorptions than those
of free ligands, indicating that the coordination of ligands can
enhance the absorption (Fig. 20 and Table 7). Complexes 1
and 2 with one 4,40-bipy or bpe ligand possess relatively
weaker absorption bands than the others with two neutral
ligands. A slight blue-shift of absorption peaks for complex 1
belongs to LLCT type19 compared with the free 4,40-bipy
ligand. On the contrary, complex 2 shows a complicated
Emission properties
The emission spectrum of 1 exhibits wondrously strong blue
emissions compared to the others. The maximal peaks are
470.5 nm in 1, 470.5 nm in 2, 470.7 nm in 3, 472.1 nm in 4,
471.3 nm in 5, and 471.4 nm in 6, respectively. All these
emissions mainly come from the 3-sb ligand,18 which are more
intense than the free 3-sb ligand. The emission strength order
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comparison of the blank experiment (kb), kb without mz, 1
without mz, and 3 without mz as shown in Fig. 21; (2) the MnII
complexes can also accelerate the reaction confirmed by the
experiments of complexes 1–6. Results showed that the
as-synthesized complex 3 is the most active catalyst for H2O2
disproportionation. The essential roles of bases have been
mentioned in similar reactions.20 We confirmed, and believe,
that the base helps the subtraction of protoꢂns in H2O2
molecules, which may help the vicinity of HO2 as nucleo-
philic reagents to the active centers of MnII catalyst.21
Kinetic parameters were obtained from the above
experiments and the results showed that the reaction is second
order. The best rate equation is 1/p = k/t + b (p is the oxygen
pressure and the t is time) and the plot is given in Fig. 22. All
parameters involved in the reactions are listed in Table 8.
Conclusion
In summary, we have successfully obtained six 3-sulfobenzoate
MnII complexes with one or two neutral ligands. Complexes 1
and 2 contain 4,40-bipy and bpe, respectively. Complexes 3–6
have two neutral ligands, in which one of the ligands is the
1,10-phenanthroline. The phen ligands all chelate to metal
centers in complexes 3–6. Therefore, such a chelating property
leads to the reduction of the coordination sites around
metal centers, resulting in the non-coordinating mode for
bpe ligands in complexes 5 and 6, and a dimeric linker and
Fig. 17 View of the 3-D hydrogen-bonding network for complex 5.
charge transfer due to the three coordination or existing modes
of the bpe ligands. The absorption peaks of complexes 3 and 4
also come from 4,40-bipy and phen ligands, and they display
similar behavior. The absorption strength of complex 4 is
stronger than that of complex 3, indicating that the coordination
of 4,40-bipy can enhance the absorption. Complexes 5 and 6
also perform similar absorption behavior, and the absorption
strength of complex 5 is stronger than that of complex 6; this
may be due to the different hydrogen-bonding forming ability
and the stacking interactions of bpe ligands in both complexes.
Table 6 Selected bond lengths (A) and angles (1) in complex 6
Mn1–O1
Mn1–N1
Mn1–N3
2.1403(15)
2.2716(18)
2.3343(18)
Mn1–O6
Mn1–N2
Mn1–N4
2.1184(16)
2.2568(18)
2.2575(19)
Catalytic activities
O1–Mn1–O6
O1–Mn1–N2
O1–Mn1–N4
O6–Mn1–N2
O6–Mn1–N4
N1–Mn1–N3
N2–Mn1–N3
N3–Mn1–N4
86.12(6)
84.62(6)
89.73(6)
159.83(7)
104.47(7)
86.05(7)
101.48(6)
72.13(7)
O1–Mn1–N1
O1–Mn1–N3
O6–Mn1–N1
O6–Mn1–N3
N1–Mn1–N2
N1–Mn1–N4
N2–Mn1–N4
112.90(7)
161.04(7)
94.27(7)
93.01(7)
73.06(7)
151.67(7)
93.37(7)
The disproportionation of hydrogen peroxide was selected for
the study of the catalytic properties of these six complexes. The
H2O2 time evolution by monitoring oxygen pressure was
measured (Fig. 21). The experiments showed that (1) the
base (imidazole, simplified as mz) is an effective assistor for
the disproportionation of hydrogen peroxide through the
Fig. 18 View of the molecular structure of complex 6. The thermal ellipsoids are drawn at 30% probability. Symmetry code: i = 1 ꢂ x, ꢂy, ꢂz.
ꢁc
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Fig. 19 View of 1-D hydrogen-bonding chain for complex 6.
(0.5 mM, 0.078 g), and H2O (15 ml) was heated at 433 K in
a 30 ml Teflon-lined stainless steel autoclave for 58.5 h. After
cooling, a colorless solution was obtained and evaporated at
room temperature. A week later, light yellow needle-shaped
crystals were precipitated. Yield: 67.0%. Elem. Anal. Calcd
for 1: C, 46.76%; H, 4.94%; N, 8.08%. Found: C, 46.52%; H,
5.01%; N, 7.89%. IR (KBr pellet, cmꢂ1): 3385(vs), 1599(vs),
1559(m), 1535(s), 1490(m), 1415(m), 1374(m), 1215(m),
1182(m), 1087(w), 1067(w), 1032(m), 1002(w), 809(s), 775(w),
667(w), 624(s).
{[Mn(3-sb)(bpe)1.5(H2O)2](bpe)0.5ꢀH2O}n (2). Mn(CH3COO)2ꢀ
4H2O (0.5 mM, 0.124 g), 3-sulfobenzoate monosodium acid
(0.3 mM, 0.068 g), 1,2-bis(4-pyridine)ethylene (0.2 mM, 0.036 g),
and H2O (10 ml) were mixed in a 20 ml Teflon-lined stainless
steel autoclave. The mixture then was heated at 423 K for
72 h. After cooling, a light yellow solution was obtained and
evaporated at room temperature. After one week, light yellow
crystals were precipitated. Yield: 47.0%. Elem. Anal. Calcd for 2:
C, 55.28%; H, 4.49%; N, 8.32%. Found: C, 55.26%; H, 4.63%;
N, 8.28%. IR (KBr pellet, cmꢂ1): 3398(s), 1608(vs), 1573(m),
1560(m), 1426(s), 1397(s), 1220(s), 1189(s), 1104(w), 1035(s),
1014(w), 998(w), 828(m), 765(m), 688(w), 667(m), 618(m), 553(s).
Fig. 20 View of the UV-vis spectra of complexes 1–6 in methanol.
non-coordinating mode for 4,40-bipy ligands in complexes 3
and 4. Thus, the hydrogen-bonding forming ability, p–p
stacking interactions, and supramolecular assembly in
complexes 3–6 are largely different under the adjustment of
the phen ligands. The diverse assembly structures lead to the
difference in thermal stability, emission properties, absorption
behavior, and catalytic activity for the disproportionation of
H2O2.
[Mn(3-sb)(phen)(H2O)3](4,40-bipy)ꢀH2O (3). Mn(CH3COO)2ꢀ
4H2O (0.5 mM, 0.123 g), 3-sulfobenzoate monosodium acid
(0.5 mM, 0.113 g) and 4,40-bipyridine (0.5 mM, 0.078 g) were
added to a mixed solution of H2O (15 ml), ethanol (5 ml), and
DMF (5 ml) in a 100 ml flask. The mixture solution was refluxed
for 2 h, and then phenanthroline (0.5 mM, 0.100 g) was added
with further 15 min reflux. After filtration, the solution was
evaporated at room temperature. A week later, light yellow block
shaped crystals were separated. Yield: 52%. Elem. Anal. Calcd
for 3: C, 52.49%; H, 4.25%; N, 8.44%. Found: C, 52.49%; H,
4.47%; N, 8.43%. IR (KBr pellet, cmꢂ1): 3369(vs), 1624(w),
1594(vs), 1555(s), 1518(m), 1426(s), 1392(vs), 1344(w), 1203(vs),
1146(m), 1093(m), 1063(w), 1034(s), 998(w), 864(w), 850(m),
810(m), 772(m), 752(w), 730(m), 698(w), 668(m), 618(s).
Experimental
Materials and physical techniques
All chemicals and solvents used in this study were commercially
obtained without further purification. The IR spectra were
measured on a Nicolet Nexus 470 spectrophotometer in the
400–4000 cmꢂ1 region in KBr pellet. Elemental analyses for C,
H, and N were carried out on a ThermoFinnigan Flash
EA1112. Thermogravimetric analysis (TGA) was performed
by a Delta Series TA-SDT Q600 in a N2 atmosphere with a
heating rate of 10 1C minꢂ1 using Al2O3 crucibles. The
fluorescence study was carried out on a powder sample at
room temperature using a Shimadzu RF-50 spectrometer. The
electronic spectra were measured on a SPECORD 2000 UV-vis
spectrophotometer in the methanol at room temperature.
[Mn2(3-sb)2(phen)2(4,40-bipy)(H2O)4] (4).
A mixture of
Mn(CH3COO)2ꢀ4H2O (0.5 mM, 0.123 g), 3-sulfobenzoate
monosodium acid (0.5 mM, 0.112 g), 4,40-bipyridine (0.5 mM,
0.078 g), and H2O (15 ml) was heated at 433 K in a 30 ml
Teflon-lined stainless steel autoclave for 72 h. After cooling,
phenanthroline (0.5 mM, 0.100 g) in DMF (5 ml) was added to
the filtration. About one week later, light yellow block-shaped
crystals were precipitated. Yield: 43%. Elem. Anal. Calcd
for 4: C, 52.46%; H, 3.67%; N, 7.65%. Found: C, 52.50%;
Synthesis
[Mn(4,40-bipy)2(H2O)4](3-sb)ꢀ3H2O (1).
A
mixture of
Mn(CH3COO)2ꢀ4H2O (0.5 mM, 0.123 g), 3-sulfobenzoate
monosodium acid (0.5 mM, 0.113 g), 4,40-bipyridine
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Table 7 UV-Vis absorption in methanol for complexes 1–6
Complex
l )
max/nm (e/dm3 molꢂ1 cmꢂ1
1
2
3
4
5
6
239.6 (33 317)
314.0 (40 465)
267.2 (43 734)
267.4 (49 330)
267.6 (75 977)
271.4 (63 366)
235.8 (32 976)
301.6 (68 974)
232.4 (69 801)
232.4 (75 082)
232.0 (109 505)
236.6 (96 272)
290.4 (69 123)
225.6 (32 702)
210.4 (78 189)
228.4(73 322)
228.4 (73 322)
233.4 (93 905)
Fig. 21 View of the catalytic behavior for complexes 1–6. The kb line for blank experiment, kb without mz is the blank experiment without
imidazole, 1 without mz and 3 without mz are termed as complexes 1 and 3 used without imidazole, respectively.
Fig. 22 The plot of 1/p vs. 1/t for complexes 1–6. The kb line for blank experiment, kb without mz is the blank experiment without imidazole,
1 without mz and 3 without mz are termed as complexes 1 and 3 used without imidazole, respectively.
ꢁc
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H, 3.64%; N, 7.66%. IR (KBr pellet, cmꢂ1): 3314(vs),
1672(w), 1651(w), 1606(s), 1592(s), 1557(w), 1516(s),
1493(w), 1424(vs), 1393(vs), 1344(w), 1210(s), 1190(vs),
1165(s), 1094(s), 1077(m), 1033(s), 997(m), 958(w), 923(w),
856(s), 801(m), 772(s), 730(s), 689(m), 666(s), 613(s).
1142(w), 1095(m), 1034(s), 999(w), 847(m), 828(w), 770(m),
726(vs), 689(m), 665(m), 617(vs), 556(m).
[Mn(3-Sb)(phen)2(H2O)](bpe)0.5ꢀH2O (6).
A mixture of
Mn(CH3COO)2ꢀ4H2O (0.5 mM, 0.123 g), 3-sulfobenzoate
monosodium acid (0.5 mM, 0.112 g), 1,2-bis(4-pyridine)ethylene
(0.4 mM, 0.073 g), and H2O (15 ml) was sealed in a 30 ml
Teflon-lined stainless steel autoclave and heated at 423 K for
3 d. After cooling, phenanthroline (0.8 mM, 0.160 g) in DMF
(5 ml) was added and evaporated at room temperature.
Several days later, light yellow block-shaped crystals were
grown. Yield: 45.0%. Elem. Anal. Calcd for 6: C, 59.84%;
H, 3.94%; N, 9.43%. Found: C, 59.67%; H, 4.04%; N, 9.06%.
IR (KBr pellet, cmꢂ1): 3537(vs), 3469(vs), 1624(m), 1593(s),
1555(m), 1516(s), 1425(s), 1381(vs), 1341(w), 1230(s), 1185(s),
1163(m), 1142(w), 1092(m), 1078(w), 1034(s), 995(w), 850(m),
835(m), 771(m), 724(s), 687(w), 662(m), 615(s), 559(m).
[Mn(3-sb)(phen)2(H2O)](bpe)0.5ꢀ5H2O (5). Mn(CH3COO)2ꢀ
4H2O (0.5 mM, 0.123 g), 3-sulfobenzoate monosodium acid
(0.5 mM, 0.112 g), 1,2-bis(4-pyridine)ethylene (0.5 mM,
0.091 g), and mixed solvents of H2O–EtOH–DMF (30 ml,
volume ratio = 4 : 1 : 1) were mixed in a 100 ml flask, and
refluxed for 2 h. Then, phenanthroline (0.5 mM, 0.100 g) in
DMF (5 ml) was added with further 15 min reflux. After
filtration, the solution was evaporated at room temperature.
After two weeks, light yellow block-shaped crystals were
grown. Yield: 41%. Elem. Anal. Calcd for 5: C, 55.55%; H,
4.58%; N, 8.60%. Found: C, 55.55%; H, 4.54%; N, 8.55%.
IR (KBr pellet, cmꢂ1): 3416(vs), 1624(m), 1598(vs), 1556(m),
1517(s), 1425(vs), 1384(vs), 1344(w), 1221(s), 1191(vs),
X-Ray structure determination
Data collections were performed on a Bruker SMART
diffractometer equipped with a CCD area detector. The data
were integrated by use of the SAINT program,22 with the
intensities corrected for Lorentz factor polarization and
absorption. The structures were solved by direct methods
and successive Fourier syntheses. Full-matrix least square
refinements on F2 were carried out using SHELXL-97
package.23 All non-hydrogen atoms were anisotropically refined.
Atom O3w in complex 1 is disordered over two positions.
The sulfonate groups in complexes 5 and 6 are disordered.
Hydrogen atoms on carbon atoms were placed in idealized
positions and refined as riding atoms, with C–H = 0.93 A and
Table 8 The kinetic parameters in catalytic reactions for complexes
1–6
Complexes
k
Equation
1
2
3
4
5
kb
31.70
22.23
20.01
39.22
47.56
60.66
94.91
85.04
81.14
47.58
1/p = 31.70/t + 0.0096
1/p = 22.23/t + 0.0030
1/p = 20.01/t + 0.0050
1/p = 39.22/t + 0.00018
1/p = 47.56/t + 0.0018
1/p = 60.66/t + 0.0068
1/p = 94.91/t + 0.016
1/p = 85.04/t + 0.015
1/p = 81.14/t + 0.012
1/p = 47.58/t + 0.0036
kb without mz
1 without mz
3 without mz
6
U
iso(H) = 1.2Ueq(C). H atoms on water molecules in 1, 2, 3, 4,
and 6 were found in the Fourier maps and refined with
Table 9 Crystallographic data and refinement parameters for complexes 1–6
Complex
1
2
3
4
5
6
Formula
Mr
C27H34MnN4O12
693.58
S
C31H30MnN4O8S C29H28MnN4O9S C24H20MnN3O7S C37H37MnN5O10
673.60
S
C37H29MnN5O7S
742.67
663.56
549.44
798.73
Crystal color/shape
Crystal size/mm
Yellow/needle
0.38 ꢃ 0.17 ꢃ
0.10
Yellow/block
0.32 ꢃ 0.23 ꢃ
Yellow/block
0.35 ꢃ 0.30 ꢃ
0.15
Yellow/block
0.30 ꢃ 0.28 ꢃ
0.12
Yellow/block
0.16 ꢃ 0.12 ꢃ
0.10
Yellow/block
0.38 ꢃ 0.14 ꢃ
0.22
0.14
ꢀ
ꢀ
Space group
a/A
b/A
c/A
a1
b1
Monoclinic, P21/c Triclinic, P1
Monoclinic, P21 Monoclinic, P21/c Monoclinic, P21/c Triclinic, P1
20.510(2)
7.0178(8)
23.495(3)
90.0
112.446(1)
90.0
3125.6(6)
4
1.470
11.7416(10)
11.9663(10)
12.9264(11)
69.042(1)
89.555(1)
67.904(1)
1554.5(2)
2
7.4415(8)
20.268(2)
10.2404(11)
90.0
107.609(1)
90.0
1472.1(3)
2
1.497
13.7428(15)
13.7074(15)
14.2123(15)
90.0
118.334(1)
90.0
2356.5(4)
2
1.549
11.5735(8)
14.5456(10)
22.7033(15)
90.0
104.600(1)
90.0
3698.6(4)
4
1.434
10.7849(15)
11.3475(16)
14.816(2)
100.909(1)
97.804(1)
109.911(1)
1634.2(4)
2
g1
V/A3
Z
D/g cmꢂ3
T/K
1.439
295 ꢄ 2
1.509
295 ꢄ 2
295 ꢄ 2
295 ꢄ 2
295 ꢄ 2
295 ꢄ 2
m/mmꢂ1
0.557
0.549
0.581
0.700
0.478
0.529
y range/1
1.1–25.2
22 010
5629
3969
1444
1.7–25.2
11 460
5549
5153
698
2.0–25.2
9285
5193
4907
686
1.7–25.2
13 083
4204
3516
1128
1.7–25.2
18 967
6658
4738
1660
1.4–25.2
12 170
5822
4817
766
Measured reflections
Unique reflections
Observed reflections
F(000)
R1 and wR2 (I 4 2s(I)) 0.055, 0.141
0.061, 0.129
0.066, 0.132
424
1.139
0.658, ꢂ0.487
0.033, 0.073
0.035, 0.074
421
1.032
0.225, ꢂ0.254
0.038, 0.090
0.047, 0.095
341
1.027
0.282, ꢂ0.273
0.064, 0.152
0.090, 0.166
560
1.127
0.669, ꢂ0.223
0.039, 0.095
0.049, 0.100
499
1.067
0.452, ꢂ0.265
R1 and wR2 (all data)
Number of variables
GOF
0.080, 0.157
455
0.991
Largest difference peak 0.859, ꢂ0.529
and hole/e Aꢂ3
ꢁc
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restriction geometries. H atoms on lattice water molecules in 5
were not added as these water oxygens have large Ueq values.
All the programs used are included in the WinGX Suite with
the version of 1.64.24 The molecular drawings were helped by
the ORTEP-III for Windows25 and Mercury software.26
Detail crystal data and structure refinements for 1–6 are listed
in Table 9.
7 (a) S. Mukhopadhyay, P. B. Chatterjee, D. Mandal, G. Mostafa,
A. Caneschi, J. van Slageren, T. J. R. Weakley and M. Chaudhury,
Inorg. Chem., 2004, 43, 3413; (b) C. Y. Chen, P. P. Chu and
K. H. Lii, Chem. Commun., 1999, 1473.
8 (a) W. S. Han and S. W. Lee, Dalton Trans., 2004, 1656; (b)
T. J. R. Weakley, Inorg. Chim. Acta, 1982, 63, 161;
(c) M. Bukowska-Strzyzewska and A. Tosik, Acta Crystallogr.,
Sect. B: Struct. Crystallogr. Cryst. Chem., 1982, 38, 265; (d) J. Tao,
X. Yin, Z. B. Wei, R. B. Huang and L. S. Zheng, Eur. J. Inorg.
Chem., 2004, 125; (e) P. Q. Zheng, L. S. Long, R. B. Huang and
L. S. Zheng, Appl. Organomet. Chem., 2003, 17, 739.
Hydrogen peroxide disproportionation study
9 (a) L. P. Zhang and L. G. Zhu, CrystEngComm, 2006, 8, 815;
(b) X. F. Zheng and L. G. Zhu, Cryst. Growth Des., 2009, 9, 4407.
10 L. P. Zhang and L. G. Zhu, Acta Crystallogr., Sect. E: Struct. Rep.
Online, 2005, 61, m1264.
11 L. P. Zhang and L. G. Zhu, Z. Anorg. Allg. Chem., 2008, 634, 39.
12 L. F. Ma, J. Q. Liu and L. Y. Wang, Synth. Rea. Inorg. Mnet.-Org.
Nano-Met. Chem., 2007, 37, 501.
A mixture of water (5 mL), imidazole (aqueous solution with
0.1 mol Lꢂ1), and DMSO (1 mL) containing an as-synthesized
complex (in the blank experiment this material was not added)
with a concentration of 0.59 ꢃ 10ꢂ3 mol Lꢂ1 in a three-necked
flask of 100 mL was stirred in a thermostated cell at 14 1C.
Three experiments were in the absence of imidazole and 1 mL
water was added (Fig. 21). The flask was connected with a
pump and a pressure gauge (APM-2D), respectively. With a
vacuum pump, an average 2.0 kPa pressure above the solution
was obtained and kept. Then zero setting was done. At this
moment, hydrogen peroxide (1 ml; H2O2 30% w/w) was
introduced into the system by a syringe and immediately the
time and the evolved oxygen pressure were recorded.
13 H. P. Xiao, X. H. Li and M. L. Hu, Acta Crystallogr., Sect.
E: Struct. Rep. Online, 2005, 61, 506.
14 S. T. Castaman, S. Nakagaki, R. R. Ribeiro, K. J. Ciuffi and
S. M. Drechsel, J. Mol. Catal. A: Chem., 2009, 300, 89.
15 M. M. Heravi, H. A. Oskooie, R. Malakooti, B. Alimadadi,
H. Alinejad and F. Behbahani, Catal. Commun., 2009, 10, 819.
16 M. Montazerozohori, M. H. Habibi, L. Zamani-Fradonbe and
S. A. R. Musavi, Arkivoc, 2008, 238.
17 (a) M. L. Tong, H. K. Lee, X. M. Chen, R. B. Huang and
T. C. W. Mak, J. Chem. Soc., Dalton Trans., 1999, 3657;
(b) R. H. Wang, F. L. Jiang, Y. F. Zhou, L. Han and
M. C. Hong, Inorg. Chim. Acta, 2005, 358, 545; (c) S. F. Lu,
Y. B. Zhu, Y. C. Liang, R. M. Yu, X. Y. Huang, F. X. Sun,
Q. J. Wu and Z. X. Huang, Acta Chim. Sinica, 2004, 62, 253.
18 X. H. Miao and L. G. Zhu, Z. Anorg. Allg. Chem., 2008, 634, 335.
19 A. Vogler and H. Kunkely, Coord. Chem. Rev., 2007, 251, 577.
20 M. Devereux, M. McCann, V. Leon, V. McKee and R. J. Ball,
Polyhedron, 2002, 21, 1063.
Acknowledgements
The authors thank the National Natural Science Foundation
of China (grant No. 50073019).
21 V. Viossat, P. Lemoine, E. Dayan, N. H. Dung and B. Viossat,
Polyhedron, 2003, 22, 1461.
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ꢁc
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2414 | New J. Chem., 2010, 34, 2403–2414