Structure characterization of several oxalate-bridged transition-metal coordination polymers

Article abstract of DOI:10.1016/j.molstruc.2006.03.079

Four oxalate-bridged transition-metal supramolecular compounds [Co₂(im)₄(ox)₂] 1, [Co(im)₂(ox)] 2, [Mn(2,2′-bpy)(ox)] 3 and [Fe(H₂O)₂(ox)] 4 (im, imidazole; ox, oxalate; bpy, bipyridine) we

Full text of DOI:10.1016/j.molstruc.2006.03.079

Journal of Molecular Structure 800 (2006) 69–73
www.elsevier.com/locate/molstruc
Structure characterization of several oxalate-bridged
transition-metal coordination polymers
Jie-Hui Yu, Qin Hou, Ming-Hui Bi, Zheng-Liang L u¨ , Xiao Zhang, Xue-Jian Qu,
Jing Lu, Ji-Qing Xu *
College of Chemistry and State Key Laboratory of Inorganic Synthesis and Preparative Chemistry, Jilin University, Changchun 130023, PR China
Received 9 February 2006; received in revised form 24 March 2006; accepted 24 March 2006
Available online 16 May 2006
Abstract
Four oxalate-bridged transition-metal supramolecular compounds [Co (im) (ox) ] 1, [Co(im) (ox)] 2, [Mn(2,2 -bpy)(ox)] 3 and
0
2
4
2
2
n+
[
(
Fe(H
2 2
O) (ox)] 4 (im, imidazole; ox, oxalate; bpy, bipyridine) were obtained from the simple hydrothermal reactions of M AoxAL
2þ
M, transition metal; L, aromatic N-donor ligand) system. They all exhibit the 1-D chain structures, consisting of the ML (or
ML ) units linked by oxalate bridges. Interestingly, the 1-D oxalate chains in the title compounds are further self-assembled into
the 3-D supramolecular networks through the interchain various secondary bonding interactions. Because the ML2 units adopt the dif-
2
2
+
2þ
ferent configuration, the oxalate chains show either zigzag type as in compounds 1–3 or linear type as in compound 4. Compounds 1 and
2
are isomeric, and only in packing modes of interchain im molecules there exists the difference.
Ó 2006 Elsevier B.V. All rights reserved.
Keywords: Oxalate; Aromatic N-donor ligand; Molecular structure; Hydrothermal synthesis
n+
1
. Introduction
a series of reactions of M AoxAL (L, aromatic N-donor
ligand and aromatic amine) system were investigated by
our group under the hydrothermal conditions. Some
interesting results are listed in Table 1 including mononu-
In the past several years, a prevalent synthetic strategy
of constructing supramolecular compounds with special
topological structures is to select a mixed ligand of organic
acid and organic base as the precursors due to potential
variety of the role played by either or both of the mixed
ligands. The material roles include (1) the pH level of syn-
thetic system, one of the important synthetic factors, can be
effectively adjusted by any of them; (2) the protonated
organic acid or organic base can service as the guests to
template the construction of host frameworks [1]; (3) the
O or N atoms from organic acid or organic base can act
as the hydrogen-bonded donor or acceptor, extending the
molecular units into high-dimension networks [2]; (4) some
new organic templates may be obtained via the in situ reac-
tions between organic acids or organic bases [3]. Recently,
0
clear [Zn(H O) (na) ] (na, nicotinate) [4], [Cd(2,2 -bbim)-
bibenzoimidazole)
[Fe (im) (ox) ] [6], [Fe(bta) (ox)] (bta, benzotriazole) [7]
and 2-D [Zn(bta)2], [Zn(im)(ox)] as well as 3-D
[Cd (ox)(OH) ] [4]. Herein, we report the structure charac-
terization of the other four coordination polymers [Co (i-
2
4
2
SO ] Æ H O
(bbim,
[5],
1-D
4
2
2
4
2
2
2
2
2
0
m) (ox) ] 1, [Co(im) (ox)] 2, [Mn(2,2 -bpy)(ox)] 3 and
4
2
2
[Fe(H O) (ox)] 4.
2
2
2. Experimental
2.1. Preparations
The syntheses were carried out in 30 ml Teflon-lined
stainless steel vessels under auto-genous pressure. The sin-
gle crystals were collected by filtration, washed with dis-
tilled water and dried in air at ambient temperature.
*
Corresponding author. Fax: +86 0431 8499158.
E-mail address: xjq@mail.jlu.edu.cn (J.-Q. Xu).
0
022-2860/$ - see front matter Ó 2006 Elsevier B.V. All rights reserved.
doi:10.1016/j.molstruc.2006.03.079

70
J.-H. Yu et al. / Journal of Molecular Structure 800 (2006) 69–73
Table 1
n+
Compounds from M AoxALAH
2
O system
O system
OAoxAimAH
n+
Entry
M
AoxALAH
Æ 2.5H
3CdSO Æ 8H
2
Product
Reference
1
2
3
4
5
6
7
8
9
CdCl
2
2
2
O
[Cd
2
(ox)(OH)
2
]
3D
0D
2D
2D
0D
1D
1D
1D
1D
1D
1D
Colorless
Colorless
Colorless
Colorless
Colorless
Red
Orange
Yellow
Purple
Ref. [4]
Ref. [5]
Ref. [4]
Ref. [4]
Ref. [4]
Ref. [6]
Ref. [7]
This work
This work
This work
This work
0
4
2
OAoxApdaAH
2
O
[Cd(2,2 -bbim)
[Zn(im)(ox)]
2
SO
4
2
] Æ H O
Zn(OAc)
Zn(OAc)
Zn(OAc)
[Fe(ox)
[Fe(ox)
[Fe(ox)
2
2
2
Æ 2H
Æ 2H
Æ 2H
2
2
2
OAoxAimAH
OAoxAbtaAH
OAoxAnaAH
2
O
O
O
2
[Zn(bta)
[Zn(H O)
[Fe (im) (ox)
[Fe(bta) (ox)]
[Fe(H O) (ox)] 4
[Co (im) (ox) ] 1
[Co(im) (ox)] 2
2
]
2
2
4
(na)
2
]
K
K
K
K
3
3
3
3
3
3
3
]AimAH
]AbtaAH
]AnaAH
]AimAH
OAbdcAimAH
OAMnCl Æ 4H OAoxAbpyAH
2
O
2
4
2
]
2
O
2
2
O
2
2
[Co(ox)
3
2
O
2
4
2
1
1
0
1
Co(ox) Æ 2H
CrCl Æ 6H
2
2
O
2
0
Purple
Yellow
3
2
2
2
2
O
[Mn(2,2 -bpy)(ox)] 3
pda, o-phenylenediamine; bdc, 1,4-benzenedicarboxylic acid.
[
Co (im) (ox) ] 1. The purple needle crystals of 1
(m), 797 (s), 751 (s), 662 (s) 619 (s). Anal. Calcd. for Co0.
C H N O : C, 33.94; H, 2.85; N, 19.79%. Found: C,
2
4
2
were obtained from a simple hydrothermal reaction of
K [Co(ox) ] (440 mg, 1.0 mmol), im (140 mg, 2.0 mmol),
5
4
4
2
2
34.07; H, 2.66; N, 20.01%.
3
3
0
and H O (20 ml) in a molar ratio of 1:2:1100 at 160 °C
[Mn(2,2 -bpy)(ox)] 3. The yellow block crystals of 3
2
for 3 days with a yield of ca. 50% based on Co. IR (KBr,
were produced from a simple hydrothermal reaction of
ꢀ
1
cm ) m: 1677 (s), 1610 (s), 1540 (m), 1442 (w), 1360 (m),
CrCl Æ 6H O (530 mg, 2.0 mmol), MnCl Æ 4H O (400 mg,
3
2
2
2
1
7
318 (m), 1142 (w), 1095 (w), 1069 (s), 830 (m), 946 (w),
97 (s), 752 (m), 662 (s), 619 (m). Anal. Calcd. for
2.0 mmol), H (ox) Æ 2H O (250 mg, 2.0 mmol), bpy
2 2
(320 mg, 2.0 mmol), NaOH (160 mg, 4.0 mmol) and H O
2
Co C H N O : C, 33.94; H, 2.85; N, 19.79%. Found:
(20 ml) in a molar ratio of 1:1:1:1:2:740 at 160 °C for 3 days
2
16 16
8
8
ꢀ1
C, 33.90; H, 2.83; N, 20.00%.
Co(im) (ox)] 2. The isomeric compound 2 with 1 was
with a yield ca. 15% based on Mn. IR (KBr, cm ) m: 1673
(s), 1612 (s), 1473 (w), 1443 (m), 1311 (m), 1164 (w), 1017
(m), 795 (m), 769 (m), 738 (w) 649 (w). Anal. Calcd. for
MnC H N O : C, 48.18; H, 2.70; N, 9.37%. Found: C,
[
2
got from another simple hydrothermal reaction. A typical
reaction mixture of Co(ox) Æ 2H O (180 mg, 1.0 mmol),
2
12
8
2
4
bdc (250 mg, 1.5 mmol), im (100 mg, 1.5 mmol),
47.99; H, 2.45; N, 9.31%.
KOH(180 mg, 3.0 mmol), H O (20 ml) in a molar ratio of
[Fe(H O) (ox)] 4. The yellow columnar crystals of
2
2
2
1
:1.5:1.5:3:1100 was fully stirred until homogeneous, then
4 were grown from identical hydrothermal reaction as
for 1 except that Hna (250 mg, 2.0 mmol) replaced
im. Yield: ca. 50% based on Fe. IR (KBr, cm ) m:
3434 (b), 1714 (s), 1682 (s), 1644 (s), 1392 (s), 1274
(m), 891 (w), 805 (m), 532 (w). Anal. Calcd. for
heated at 160 °C for 5 days to give purple needle crystals
ꢀ
1
ꢀ1
of 2. Yield: ca. 57% based on Co. IR (KBr, cm ) m:
677 (s), 1612 (s), 1540 (m), 1442 (m), 1359 (m), 1318
m), 1260 (m), 1142 (m), 1094 (m), 1068 (s), 945 (m), 830
1
(
Table 2
Crystal data and structure refinement for the title compounds
1
2
3
4
Empirical formula
Formula weight
Crystal
Co
566.23
Triclinic
P-1
2
C
16
H
N
16 8
O
8
Co0.5
C
4
H
4
N
2
O
2
MnC12
299.14
H
8
N
2
O
4
Fe0.5CH
89.95
2 3
O
141.56
Monoclinic
C2/c
13.372 (2)
10.296 (2)
9.080 (3)
Orthorhombic
Pna2
Monoclinic
C2/c
12.016 (2)
5.558 (1)
9.705 (2)
Space group
1
˚
a (A)
8.463 (2)
9.674 (2)
9.2890 (2)
13.921 (3)
˚
b (A)
11.494 (2)
13.020 (3)
81.92 (3)
72.55 (3)
83.16(3)
1192.2 (4)
2
1.577
1.448
8289
5314
˚
c (A)
a (°)
b (°)
c (°)
97.67 (2)
126.93 (3)
˚
3
V (A )
1239.0 (5)
8
1.518
1.393
1439
1250.9 (4)
4
1.588
1.066
11490
518.1 (2)
8
2.307
2.865
1060
Z
ꢀ1
l (mm
)
ꢀ
3
D (g Æ cm
)
Reflections collected
Unique reflections
1083
2827
575
R
S
int
0.0740
0.808
0.0220
1.093
0.0377
1.058
0.0675
1.128
Final R
1
, wR
2
[I>2r (I)]
0.0498, 0.0715
0.1639, 0.0926
0.0427, 0.1170
0.0488, 0.1203
0.0307, 0.0661
0.0412, 0.0712
0.0328, 0.0828
0.0400, 0.0852
(All data)

J.-H. Yu et al. / Journal of Molecular Structure 800 (2006) 69–73
71
Fe0.5CH O : C, 13.35; H, 2.24%. Found: C, 13.22; H,
disorder. Basic information pertaining to the crystal
parameters and structure refinement of the title compounds
is summarized in Table 2. CCDC numbers for compounds
1–4 are 296310–296313.
2
3
2
.13%.
2
.2. Physical measurement
C, H and N analyses were performed with a Perkin-
3. Results and discussion
Elmer 2400LS II elemental analyzer. Infrared spectra were
recorded with Perkin-Elmer Spectrum 1 spectrophotometer
in the 4000–400 cm region using a powdered sample on a
KBr plate.
From Table 1, some viewpoints can be realized: (i) tran-
ꢀ
1
sition metal salts in reaction with ox tend to form the chain
0
compounds with the common formulas of [M(L ) (ox)] or
2
00
0
00
[
M(L )(ox)] (L , monodentate ligand, L , bidentate ligand)
as displayed by Entries 6-11 and correlative literatures [6–
], whereas Zn and Cd may be self-assembled into the novel
2
.3. X-ray structure determination
8
Data were collected with Mo Ka radiation
k = 0.71073 A) on a Siemens P4 diffractometer for 2 and
and on a Rigaku R-AXIS RAPID IP diffractometer for
and 3. The structures were solved using weight-atom
frameworks according to Entries 1–5 and correlative liter-
atures [9]; (ii) according to Entry 2 the in situ reaction
between ox and bda can give a novel aromatic N-donor
ligand bbim, which can be used to assemble new com-
pounds; (iii) although sometimes ox or L did not appear
in the resulting framework, at least they adjusted the pH
level of synthetic system. For instance, im in Entry 1 pro-
vided the OH source.
˚
(
4
1
methods except 4 using direct methods with SHELXTL
program, and refined by full-matrix least-squares tech-
niques. The non-hydrogen atoms were assigned anisotropic
displacement parameters in the refinement and the hydro-
gen atoms of aromatic rings were treated using a riding
0
With aromatic monodentate N-donor ligands (L ) as the
2
2þ
model. The structure was then refined on F with SHEL-
ancillary ligands, the ML2 units generally adopt cis-con-
XL-97. The structure of 3 can be obtained in a centered
space group P nma, but both ox and bpy encounter serious
figuration, held together by tetradentate oxalate ligands
into an infinite zigzag chain. The reported compounds
2 4 2 2
Fig. 1. 2-D supramolecular sheets of [Co (im) (ox) ] 1 (a) and [Co(im) (ox)] 2 (b).

72
J.-H. Yu et al. / Journal of Molecular Structure 800 (2006) 69–73
0
[
[
Zn(py) (ox)] (py, pyridine) [8b], [Zn(py) (ox) Æ H O] [8a],
In general, in these compounds as the reported [M (2,2 -
2
2
2
2
0
Cu(3-OHpy) (ox)] [8g] and [Fe (im) (ox) ] [6] are the
bpy) (ox) ] Æ 2H O (M, Cu [8f], Cd [8c]), [M(2,2 -dpa)(ox)]
2
2
4
2
2
2
2
typical examples. Im can act as bridging ligand in nature,
(M, Fe, Ni [8d], Co [8e]; dpa, dipyridylamine), various
but in compounds [Co (im) (ox) ] 1 and [Co(im) (ox)] 2,
C(or N)AHꢁ ꢁ ꢁO hydrogen-bonded interactions together
2
4
2
2
00
it bonds to the metal center only via the monodentate
mode. As shown in Fig. 1, compounds 1 and 2 are isomor-
phous with each other. The unique structural difference is
the packing mode amongst interchain im molecules. In 2
im molecules just adopt the offset face-to-face packing,
whereas in 1 there exists another edge-to-face packing with
a dihedral angle of 76.8 °C besides the face-to-face packing.
Interestingly, in two compounds the protonated N atoms
with the p–p packing interactions amongst L molecules
play a rather important role in propagating the 1-D oxalate
chains into 2-D or 3-D supramolecular networks. Com-
0
pound [Mn(2,2 -bpy)(ox)] 3 is another example of this fam-
ily. Fig.
2
shows the interchain supramolecular
interactions. In [001] direction, the bipyridine rings array
˚
parallel to each other characterized by a distance of 3.9 A
along the a axis, meanwhile, C8 of pyridine molecule forms
2þ
of cis-CoðimÞ2 units hydrogen bond to the O atoms
of adjacent oxalate chains, extending the 1-D oxalate
chains along two directions into 3-D supramolecular
the hydrogen bond with O1 of oxalate of neighboring chain
˚
(C8ꢁ ꢁ ꢁO1 = 3.159 A C8AHꢁ ꢁ ꢁO1 = 122.5°). Through these
weak interactions, the 1-D oxalate chains are self-assem-
bled into a 2-D supramolecular layer [see Fig. 2(a)]. In
[100] direction, via the C2AHꢁ ꢁ ꢁO4 hydrogen bonds, the
2-D supramolecular layers are interconnected finally into
˚
networks (1: N6ꢁ ꢁ ꢁO7 = 2.792 A N6AHꢁ ꢁ ꢁO7 = 159°
˚
N2ꢁ ꢁ ꢁO5 = 2.780 A
N2AHꢁ ꢁ ꢁO5 = 164°,
N8ꢁ ꢁ ꢁO2 =
˚
˚
2
.760 A N8AHꢁ ꢁ ꢁO2 = 164°, N4ꢁ ꢁ ꢁO3 = 2.792 A N4AH
˚
ꢁ
ꢁ ꢁO3 = 166°; 2: N2ꢁ ꢁ ꢁO1 = 2.770 A N2AH ꢁ ꢁ ꢁ O1 =
69°).
With aromatic chelate ligands (L ) as the auxiliary
ligands, the oxalate chains still take on the zigzag type.
a
3-D supramolecular network along the
c
axis
˚
1
(C2ꢁ ꢁ ꢁO4 = 3.319 A C2AHꢁ ꢁ ꢁO4 = 154.5°) [see Fig. 2(b)].
00
Once the N-donor ligands are the bridging ones, the
2
2
þ
ML units will adopt the trans-configuration, and the
0
Fig. 2. Supramolecular interactions in [Mn(2,2 -bpy)(ox)] 3.

J.-H. Yu et al. / Journal of Molecular Structure 800 (2006) 69–73
73
2 2
Fig. 3. Hydrogen-bonded network in [Fe(H O) (ox)] 4.
oxalate chains will show the linear type, extended further
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˚
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ꢁ ꢁOw = 153.73°; O2ꢁ ꢁ ꢁOw = 2.746 A, O2AHꢁ ꢁ ꢁOw =
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[
Supplementary data associated with this article can be
found, in the online version, at doi:10.1016/j.molstruc.
(
2
006.03.079.