Synthesis and crystal structure of Mn(II) and Zn(II) complexes with 1,3,5-tris(carboxymethoxyl)benzene ligand

Article abstract of DOI:10.1007/s10870-006-9164-7

Two complexes (H₂bipy)[M₂(TB)₂(H ₂O)₈]?5H₂O (M = Mn 1, Zn 2) (bipy = 4,4′-bipyridine, H₃TB = 1,3,5-tris(carboxymethoxyl)benzene) were synthesized by the reaction of the correspon

Full text of DOI:10.1007/s10870-006-9164-7

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Journal of Chemical Crystallography, Vol. 37, No. 3, March 2007 ( 2007)
DOI: 10.1007/s10870-006-9164-7
Synthesis and crystal structure of Mn(II) and Zn(II)
complexes with 1,3,5-tris(carboxymethoxyl)
benzene ligand
Gang Wu,(1) Yan Wang,(1) Xiao-Feng Wang,(1) Hiroyuki Kawaguchi,(2) and Wei-Yin Sun(1)∗
Received January 4, 2006; accepted October 17, 2006
Published Online February 3, 2007
Two complexes (H2bipy)[M2(TB)2(H2O)8] · 5H2O (M = Mn 1, Zn 2) (bipy = 4,4ꢁ-
bipyridine, H3TB = 1,3,5-tris(carboxymethoxyl)benzene) were synthesized by the re-
action of the corresponding metal salt with ligand H3TB and 4,4ꢁ-bipy in an aqueous
methanol solution at room temperature, respectively. Their structures were determined by
single crystal X-ray diffraction analysis. Both complexes 1 and 2 crystallize in the triclinic
¯
space group P1 with the crystal parameters of 1: a = 9.725(12) Å, b = 10.651(13) Å,
c = 10.882(13) Å, α = 91.72(2)◦, β = 96.41(2)◦, γ = 97.72(2)◦, V = 1109(2) Å3,
Z = 1 and 2: a = 9.610(10) Å, b = 10.55(2) Å, c = 10.83(2) Å, α = 91.60(4)◦,
β = 95.32(2)◦, γ = 97.73(4)◦, V = 1082(3) Å3, Z = 1. Complexes 1 and 2 have
the same dinuclear structure, in which each metal atom is six coordinated with distorted
octahedral geometry by two oxygen atoms from two different TB3− ligands and four ones
from four coordinated water molecules. The dinuclear units are further linked by hydrogen
bonding and π–π interactions to form the three-dimensional framework structure.
KEY WORDS: Mn(II) complex; Zn(II) complex; crystal structure; carboxylate ligand; π–π interactions; hy-
drogen bonds.
Introduction
Studies on metal-organic frameworks
(MOFs) are of great current interests, due to
their novel structure, interesting properties and
potential applications as new materials, for
example, molecular magnets, catalysts, and so
on.1,2 In the building MOFs, it is important to
design organic ligands and to choose suitable
metal ion with definite coordination geometry.
In addition to the coordination interactions, the
results reported to now show that non-covalent
interactions such as π–π and hydrogen bonding
interactions are also very important in deter-
mining the structure and property of MOFs.3–8
Therefore, organic ligands with aromatic moiety
and hydrogen bonding ability are often used
to react with varied metal salts to assembly
into novel MOFs. Among the reported organic
ligands, those containing benzenecarboxylates
are an important family because they combine
the principles of supramolecular chemistry along
with favorable π–π and hydrogen bonding
interactions, which may result in fascinating and
interesting structures and properties.
(1)
State Key Laboratory of Coordination Chemistry, School of
Chemistry and Chemical Engineering, Coordination Chemistry
Institute, Nanjing University, Nanjing 210093, China.
Coordination Chemistry Laboratories, Institute for Molecular
(2)
Science, Okazaki Aichi 444-8585, Japan.
To whom correspondence should be addressed; e-mail:
∗
sunwy@nju.edu.cn.
199
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1074-1542/07/0300-0199/0 2007 Springer Science+Business Media, LLC

200
Wu, Wang, Wang, Kawaguchi, and Sun
Table 1. Crystal Data and Refinement Results for Complexes 1
and 2
HO
O
Complex
1
2
O
Empirical formula
Formula weight
Crystal system
Space group
a (Å)
C34H54N2Mn2O31
1096.67
triclinic
¯
P1
9.725(12)
10.651(13)
10.882(13)
91.72(2)
96.41(2)
97.72(2)
1109(2)
1
C34H54N2Zn2O31
1117.53
triclinic
¯
P1
9.610(10)
10.55(2)
10.83(2)
91.60(4)
95.32(2)
97.73(4)
1082(3)
1
O
O
O
O
b (Å)
HO
OH
c (Å)
α (◦)
β (◦)
H3TB
γ (◦)
V (Å3)
Scheme 1. Structure of ligand H3TB.
Z
Crystal size (mm)
0.25 × 0.25 × 0.25
0.30 × 0.25 × 0.25
Dc (g cm−3
)
1.642
1.714
µ (mm−1
2θ max (◦)
)
0.677
50.00
1.219
50.00
We are interested in MOFs with flexible
Reflns. collected
Independent reflns.
Obsd. reflns.
(I > 2σ(I))
Parameters refined
Rint
7127
3728
3348
6958
3626
3396
tripodal ligands with imidazole or carboxylate
coordination moieties.9,10 In this paper, we
designed a new organic ligand containing
benzene ring and carboxyl groups, namely 1,3,5-
tris(carboxymethoxyl)benzene(H3TB)(Scheme 1),
and reactions with transition metal salts were
carried out. Here we report the synthesis,
structural characterization of coordination
compounds (H2bipy)[Mn2(TB)2(H2O)8] · 5H2O
(1) and (H2bipy)[Zn2(TB)2(H2O)8] · 5H2O (2)
(bipy = 4,4ꢁ-bipyridine) obtained by reaction
of ligand H3TB with Mn(ClO4)2 · 6H2O and
ZnCl2 salts, respectively. The three-dimensional
frameworks are sustained by non-covalent π–π
interactions and hydrogen bonds.
365
0.0532
0.8489/0.8489
0.0418
0.1148
1.048
0.524; − 0.470
373
0.0494
0.7504/0.7113
0.0351
0.0946
1.050
0.493; − 0.567
Tmax/Tmin
R (I > 2σ(I))
wR2 (I > 2σ(I))
Goodness of fit
Residual electron
density (eÅ−3
)
ments were performed on the Bruker DRX-500
spectrometer.
Structure determinations
Experimental
The data collections for complexes 1 and 2
were carried out on a Rigaku Saturn CCD area
detector at 173 K, using graphite-monochromated
Mo-Kα radiation (λ = 0.7107 Å). The structures
were solved by direct method using SHELX-9711
and refined by full-matrix least-squares methods
anisotropically for non-hydrogen atoms. The hy-
drogen atoms except for those of water molecules
were generated geometrically, while the ones of
six water molecules were found in the differential
Fourier map and located directly. However, the
hydrogen atoms of uncoordinated water molecule
General
All commercially available chemicals are of
reagent grade and used as received without further
purification. Solvents were purified according to
the standard methods. C, H and N elemental anal-
yses were carried out on a Perkin-Elmer 240C el-
emental analyzer at the analysis center of Nanjing
University. Infrared (IR) spectra were recorded
on a Bruker Vector22 FT-IR spectrophotometer
by using KBr discs.1H NMR spectral measure-

Synthesis and crystal structure of Mn(II) and Zn(II) complexes
201
Table 2. Selected Bond Lengths [Å] and Angles [◦] for Complexes 1 and 2
1
–
–
Mn1 O1
2.155(2)
2.200(2)
2.153(2)
92.32(10)
173.05(6)
171.95(6)
90.38(9)
89.01(9)
85.05(10)
93.73(9)
175.76(6)
Mn1 O10
2.191(3)
2.229(2)
2.187(2)
95.72(10)
91.47(10)
82.17(10)
89.85(10)
92.78(10)
87.36(9)
90.47(10)
–
–
Mn1 O11
Mn1 O12
a
–
–
Mn1 O4
– –
O1 Mn1 O11
– –
O1 Mn1 O13
– –
O10 Mn1 O12
Mn1 O13
–
–
O1 Mn1 O10
O1 Mn1 O12
–
–
–
–
–
–
O10 Mn1 O11
–
– –
O11 Mn1 O12
O10 Mn1 O13
–
–
–
O11 Mn1 O13
O12 Mn1 O13
a
a
–
–
– –
O10 Mn1 O4
– –
O12 Mn1 O4
O1 Mn1 O4
a
a
a
–
–
–
O11 Mn1 O4
–
O13 Mn1 O4
2
–
–
Zn1 O1
2.120(3)
Zn1 O10
2.104(3)
–
–
Zn1 O11
2.094(3)
2.061(3)
Zn1 O12
2.141(3)
2.070(3)
b
–
–
Zn1 O13
Zn1 O4
–
–
–
–
–
O1 Zn1 O10
91.60(11)
91.60(13)
172.04(7)
90.66(11)
89.46(10)
83.55(13)
93.71(13)
93.70(13)
O1 Zn1 O11
88.66(10)
176.56(6)
89.01(13)
83.03(13)
91.03(13)
94.22(13)
174.23(6)
–
– –
O1 Zn1 O13
– –
O10 Zn1 O12
– –
O11 Zn1 O12
O12 Zn1 O13
– –
O10 Zn1 O4
– –
O12 Zn1 O4
O1 Zn1 O12
–
–
O10 Zn1 O11
O10 Zn1 O13
O11 Zn1 O13
–
–
–
–
–
–
b
b
–
–
O1 Zn1 O4
b
b
b
–
–
O11 Zn1 O4
O13 Zn1 O4
–
–
Note. Symmetry transformation used to generate equivalent atoms:a1 − x, 2 − y, 2 − z;b2 − x, 1 − y, 1 − z.
at special position (O16) could not be found.
Calculations were performed on a personal com-
puter with the Siemens SHELXTL program pack-
age.12 The crystal parameters, data collection and
refinement results for the compounds are listed
in Table 1. The selected bond lengths and bond
angles are listed in Table 2.
Fig. 1. The coordination environment of Mn (II) atom in 1 with thermal ellipsoids at 30% probability,
the uncoordinated water molecules and hydrogen atoms are omitted for clarity.

202
Wu, Wang, Wang, Kawaguchi, and Sun
Fig. 2. Infinite 2D network structure of complex 1, in which the hydrogen bonds are presented by
dashed lines.
Synthesis of ligand
After the evaporation of DMF under vacuum
1,3,5-tris(carboxymethoxyl)benzene (H3TB)
condition, the mixture was dissolved in water.
Then concentrated sulfuric acid was added
slowly to the aqueous solution until pH = 3
under ice bath condition. The product H3TB was
obtained by filtration, and washed by water till
sulfate anions were removed completely, then
dried in vacuum to give a pale yellow powder
in 55% yield. Calcd. for C12H12O9 (%): C,
48.01; H, 4.03; found (%): C, 48.10; H, 4.12. IR
data (KBr pellet, cm−1): 1722s, 1612s, 1540s,
1431m, 1261m, 1173s, 1093w, 811w.1H NMR
(500 MHz, D2O): δ 6.18 (s, 3H); 4.78 (s, 6H).
Ligand H3TB was prepared by a sim-
ilar method reported for the synthesis of
α,αꢁ-bis-(3,5-bis(phenylthiamethyl)phenyloxy)-
αꢁꢁ-phthalimidomesitylene.13
A
mixture of
chloroacetic acid (12.29 g, 130 mmol) and
K2CO3 (9.67 g, 70 mmol) in DMF (30 mL)
was stirred 1 h at room temperature. Then a
mixture of phloroglucinol (4.5 g, 36 mmol) and
K2CO3 (16.59 g, 120 mmol) in DMF (30 mL),
which have been stirred for 1 h, was added. The
mixture was further stirred 12 h at 74–78◦C.
Fig. 3. Crystal packing diagram for complex 1 in which the hydrogen bonds are indicated by dashed lines.

Synthesis and crystal structure of Mn(II) and Zn(II) complexes
203
Table 3. Bond Lengths and Angles of Hydrogen Bonding for Complexes 1, 2
◦
–
–
–
– –
D H· · ·A
D· · ·A [Å]
D H A
D H A [ ]
1
a
–
–
–
–
O10 H14· · ·O8
2.754(4)
2.725(4)
2.848(4)
3.025(4)
2.793(4)
2.727(4)
3.160(5)
2.694(4)
2.669(4)
2.695(4)
2.905(4)
2.794(4)
3.093(5)
2.786(4)
2.747(4)
3.503(5)
3.100(5)
3.055(5)
O10 H14 O8
167
176
133
152
158
170
174
157
164
162
154
164
127
175
171
177
127
127
a
– –
O10 H14B O3
– –
O11 H15 O9
– –
O12 H16 O6
– –
O11 H15B O4
– –
O12 H16 O5
– –
O12 H16B O8
– –
O13 H17 O2
– –
O13 H17B O7
– –
O14 H18 O15
– –
O14 H19 O5
– –
O15 H20 O5
– –
O15 H20 O5
– –
O15 H21 O2
– –
N1 H22 O8
– –
C8 H5 O2
O10 H14B· · ·O14
b
–
O11 H15· · ·O1
b
–
O11 H15· · ·O3
c
–
O11 H15B· · ·O4
d
–
O12 H16· · ·O5
e
–
–
–
–
O12 H16B· · ·O8
–
O13 H17· · · O2
f
O13 H17B· · ·O7
g
O14 H18· · ·O15
h
–
O14 H19· · ·O5
c
–
O15 H20· · ·O5
c
–
O15 H20· · ·O6
f
–
O15 H21· · ·O2
i
–
–
N1 H22· · ·O8
f
C8 H5· · ·O2
i
–
–
–
C17 H13· · ·O7
C17 H13 O7
b
–
–
C17 H13· · ·O12
C17 H13· · ·O12
2
j
–
–
–
O10 H14· · ·O1
2.762(6)
3.012(6)
2.709(6)
2.720(6)
3.302(7)
2.687(6)
2.646(6)
2.674(6)
2.919(6)
3.172(7)
2.689(6)
2.796(6)
2.783(6)
3.085(6)
2.710(6)
3.454(7)
3.068(7)
3.059(7)
O10 H14 O1
171
171
177
173
149
169
162
150
153
135
166
174
162
128
176
178
128
130
g
–
– –
O10 H14B O6
– –
O11 H15 O8
– –
O11 H15B O14
– –
O12 H16 O8
– –
O12 H16B O2
– –
O13 H17 O7
– –
O13 H17B O5
– –
O14 H18 O2
– –
O14 H18 O15
– –
O14 H19 O15
– –
O15 H20 O5
– –
O15 H21 O2
– –
O15 H21 O3
– –
N1 H22 O8
– –
C6 H4 O5
– –
C17 H13 O7
O10 H14B· · ·O6
i
–
O11 H15· · ·O8
j
–
O11 H15B· · ·O14
k
–
O12 H16· · ·O8
–
O12 H16B· · ·O2
l
–
O13 H17· · ·O7
m
–
O13 H17B· · ·O5
n
–
O14 H18· · ·O2
a
–
–
O14 H18· · ·O15
◦
O14 H19· · ·O15
l
–
O15 H20· · ·O5
j
–
O15 H21· · ·O2
j
–
O15 H21· · ·O3
i
–
–
N1 H22· · ·O8
p
C6 H4· · ·O5
i
–
C17 H13· · ·O7
c
–
– –
C17 H13 O12
C17 H13· · ·O12
Note. Symmetry transformation used to generate equivalent atoms:a1 − x, 1 − y, 2 − z; b2 − x, 2 − y, 2 − z;
c1 + x, y, z; d1 − x, 2 − y, 2 − z; e1 + x, 1 + y, 1 + z; f 2 − x, 1 − y, 2 − z; g − 1 + x, y, z; h − x, 1 − y, 1 − z;
i
j
l
◦
x, 1 + y, z; 1 − x, 1 − y, 1 − z; k1 − x, − y, − z; -1 + x, 1 + y, z; m2 − x, 1 − y, 1 − z; nx, y, 1 + z; x,
− 1 + y, z; p3 − x, − y, 1 − z.
Synthesis of complex
(H2bipy)[Mn2(TB)2(H2O)8] · 5H2O (1)
perature for 0.5 h, the clear solution was allowed
to stand at room temperature for two weeks. Block
yellow crystals were obtained in 41% yield. Ele-
mental analysis calcd for C34H54N2Mn2O31 (%):
C, 37.24; H, 4.96; N, 2.55. Found (%): C, 37.41;
H, 5.04; N, 2.68. IR data (KBr pellet, cm−1):
1613bs, 1415m, 1326w, 1170m, 1078w, 808w.
Mn(ClO4)2 · 6H2O (21.6 mg, 0.06 mmol),
H3TB (18 mg, 0.06 mmol), 4,4ꢁ-bipy (14 mg,
0.09 mmol) were added to 10 mL of CH3OH and
H2O (v/v 1:1), and after being stirred at room tem-

204
Wu, Wang, Wang, Kawaguchi, and Sun
Synthesis of complex
(H2bipy)[Zn2(TB)2(H2O)8] · 5H2O (2)
Complex 2 was prepared by the same method
as that of complex 1 except Mn(ClO4)2 · 6H2O
replaced by ZnCl2 (8.2 mg, 0.06 mmol). Prism
yellow crystals were isolated after four weeks
in 35% yield. Elemental analysis calcd for
C34H54N2Zn2O31 (%): C, 36.54; H, 4.87; N,
2.51. Found (%): C, 37.06; H, 4.91; N, 2.61. IR
data (KBr pellet, cm−1): 1611bs, 1417m, 1325w,
1167m, 1072w, 810w.
Results and discussion
Fig. 4 Diagram for complex 1 with π–π interactions indi-
Single crystal X-ray analysis reveals that
complexes 1 and 2 crystallize in the same space
group with similar cell parameters as summarized
in Table 1, and they are isomorphous and isostruc-
tural. Thus only the structure of 1 is described here
in detail as an example. In complex 1, the asym-
metric unit consists of a Mn(II) atom, a ligand
TB3−, four coordinated and two and half unco-
ordinated water molecules, an half of protonated
4,4ꢁ-bipy, which acts as counterion. As shown in
Fig. 1, each Mn(II) center is six coordinated by six
oxygen atoms with a distorted octahedral geome-
try, four of which come from four H2O molecules,
while the other two are from two different TB3−
cated by dashed lines.
It is noteworthy that the Mn2(TB)2 metal-
locyclic rings are connected together through the
–
O H· · ·O hydrogen bonding interactions between
the coordinated water molecules and the oxy-
gen atoms of the uncoordinated carboxyl groups
of neighboring Mn2(TB)2 metallocyclic molecule
to give extended two-dimensional (2D) network
structure as illustrated in Fig. 2. Furthermore,
–
–
there areN H · · ·O and C H · · ·O hydrogen bonds
in complex 1, which lead to the formation of three-
dimensional (3D) structure (Fig. 3). The proto-
nated 4,4ꢁ-bipy takes part in the formation of hy-
–
ligands. The Mn O bond distances are in the range
of 2.153(2) to 2.229(2) Å(Table 2), which are in
–
–
–
agreement with those of the reported Mn O bond
drogen bond N1 H22 · · ·O8 with N1 O8 distance
of 2.747(4) Å in complex 1. The hydrogen bond-
ing data are summarized in Table 3. In addition,
the π–π interactions also play important role in
formation of the packing structure of complexes 1
and 2. Face-to-face π–π interaction is observed in
complex 1. The distance between the centroids of
the benzene ring of ligand TB3− and the pyridine
ring of the protonated 4,4ꢁ-bipy is 3.30 Å and the
dihedral angle between these two aromatic rings is
2.4◦ (in complex 2, the corresponding centroid-to-
centroid distance is 3.26 Å, and the dihedral angle
is 2.9◦), which are comparable to the previously
reported π–π interactions (Fig. 4).15
lengths.14 On the other hand, all carboxyl groups
of the H3TB ligand are completely deprotonated
in 1 and 2, which is confirmed by infrared spec-
tral measurements since no strong band around
1722 cm−1 for COOH of free H3TB ligand was
–
observed in 1 and 2. The carboxyl group of the
TB3− ligand coordinates to the metal atom in the
monodentate mode and each TB3− ligand uses its
two of three carboxyl groups to link two Mn(II)
atoms, while the third one is free of coordination
(Fig. 1). Therefore, two Mn(II) atoms are linked
by two TB3− ligands to give rise to a molecular
Mn2(TB)2 metallocyclic ring.

Synthesis and crystal structure of Mn(II) and Zn(II) complexes
205
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In summary, the complexes 1 and 2 were
obtained by reactions of tricarboxylate ligand with
metal salts. The dinuclear M2(TB)2 (M = Mn,
Zn) metallocyclic molecules of complexes 1 and 2
–
–
are linked together through O H· · ·O, N H · · ·O,
–
C H · · ·O hydrogen bonds and π–π interactions
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Supplementary Material Crystallographic data (excluding struc-
ture factors) for the structures in this paper has been deposited with
the Cambridge Crystallographic Data Center as supplementary pub-
lication number CCDC 294381 and 294382. Copies of the data can
be obtained, free of charge, on application to CCDC, 12 Union Road,
Cambridge CB2 1EZ, UK (Fax: + 44(0)-1223–336033 or e-mail:
deposit@ccdc.cam.ac.uk).
Acknowledgments
The authors are grateful to the National Nat-
ural Science Foundation of China (Grant No.
20231020) for financial support of this work.
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