Two fumarato-bridged Co(II) coordination polymers: Syntheses, crystal structures and properties of Co(H2O)4L and [Co 3(H2O)4(OH)2L2] ·2H2O with H2L=HOOCCH=CHCOOH

Article abstract of DOI:10.1016/j.jssc.2003.11.008

Two fumarato-bridged Co(II) coordination polymers Co(H₂O) ₄L 1 and [Co₃(H₂O)₄(OH) ₂L₂]·2H₂O 2 with H₂L=HOOCCH =CHCOOH were prepared. Complex 1 consists of polymeric chains _∞¹[Co(H₂O)₄(C ₄H₂O₄)_2/2], which result from octahedrally coordinated Co atoms bridged by bis-monodentate fumarate anions and are assembled by interchain hydrogen bonds. Within 2, the edge-shared Co₂O₁₀ bi-octahedra are connected to the CoO₆ octahedra to form 1D cobalt oxide chains and 3D open framework generated from the chains inter-linked by bis-bidentate fumarate anions displays rhombic tunnels, which are filled with the lattice H₂O molecules. Thermal and magnetic behaviors of both the title coordination polymers are discussed. Crystal data: (1) monoclinic, P2₁/c, Z=4, a=7.493(1)A, b=14.377(1)A, c=7.708(1)A, β=99.54(1)°, V=818.9(2)A³, R₁=0.0304, and wR₂=0.0669 for 1487 observed reflections (I≥2σ(I)) out of 1877 unique reflections; (2) monoclinic, P2₁/c, Z=2, a=6.618(1)A, b=8.172(2)A, c=15.578(3)A, β=96.30(3)°, V=837.4(3)A³, R₁=0.0360 and wR₂=0.0663 for 1442 observed reflections (I≥2σ(I)) out of 1927 unique reflections.

Full text of DOI:10.1016/j.jssc.2003.11.008

ARTICLE IN PRESS
Journal of Solid State Chemistry 177 (2004) 1352–1358
Two fumarato-bridged Co(II) coordination polymers: syntheses,
crystal structures and properties of Co(H2O)4L and
½Co3ðH2OÞ4ðOHÞ2L2Š Á 2H2O with H2L ¼ HOOCCH ¼ CHCOOH
Yue-Qing Zhengà and Hong-Zhen Xie
Institute for Solid State Chemistry, Ningbo University, Municipal Key Laboratory of Inorganic Materials Chemistry, Ningbo 315211, China
Received 7 July 2003; received in revised form 11 October 2003; accepted 7 November 2003
Abstract
Two fumarato-bridged Co(II) coordination polymers Co(H2O)4L 1 and [Co3(H2O)4(OH)2L2] Á 2H2O 2 with H2L ¼ HOOCCH ¼
1
N
CHCOOH were prepared. Complex 1 consists of polymeric chains ½CoðH2OÞ4ðC4H2O4Þ2=2Š; which result from octahedrally
coordinated Co atoms bridged by bis-monodentate fumarate anions and are assembled by interchain hydrogen bonds. Within 2, the
edge-shared Co2O10 bi-octahedra are connected to the CoO6 octahedra to form 1D cobalt oxide chains and 3D open framework
generated from the chains inter-linked by bis-bidentate fumarate anions displays rhombic tunnels, which are filled with the lattice
H2O molecules. Thermal and magnetic behaviors of both the title coordination polymers are discussed. Crystal data: (1) monoclinic,
P21=c; Z ¼ 4; a ¼ 7:493ð1Þ A, b ¼ 14:377ð1Þ A, c ¼ 7:708ð1Þ A, b ¼ 99:54ð1Þꢀ, V ¼ 818:9ð2Þ A3, R1 ¼ 0:0304; and wR2 ¼ 0:0669 for
1487 observed reflections (IX2sðIÞ) out of 1877 unique reflections; (2) monoclinic, P21=c; Z ¼ 2; a ¼ 6:618ð1Þ A, b ¼ 8:172ð2Þ A,
c ¼ 15:578ð3Þ A, b ¼ 96:30ð3Þꢀ, V ¼ 837:4ð3Þ A3, R1 ¼ 0:0360 and wR2 ¼ 0:0663 for 1442 observed reflections (IX2sðIÞ) out of
1927 unique reflections.
r 2003 Elsevier Inc. All rights reserved.
Keywords: Cobalt(II); Coordination polymer; Crystal structures; Properties
1. Introduction
hydroxide and succinate groups to transition metal
atoms tends to form coordination polymers with 3D
open framework [12]. Compared to the succinate anions,
fumarate anions exhibit less conformational freedom
due to the C ¼ C double bond. To the best of our
knowledge, few coordination polymers based on
metal fumarato ligand have been reported yet [13].
Here, we present two new Co(II) coordination poly-
mers, CoðH OÞ4ðC4H2O4Þ 1 and ½Co3ðH2OÞ4ðOHÞ2
ðC H2O4Þ Š Á22H O 2. The Co atoms in the former are
An enormous expansion of the research field of
coordination polymers based on metal-organic ligand
coordination is motivated by the interest in creating
structures with cavities and channels of potential use in
nanotechnology, shape and size selectivity catalysis,
separations and molecular recognition [1,2]. Rigid
dicarboxylate ligands have been exploited to generate
a variety of coordination polymers with open frame-
works [3,4]. In recent years, growing attention has been
paid to rational design and synthesis of coordination
polymers by utilization of saturated aliphatic dicarbox-
ylate ligands, since the flexibility and conformational
freedom of such ligands could give rise to a variety of
interesting structural motifs [5–11]. Among the satu-
rated a;o-dicarboxylate anions, the succinate ligands are
of special interest. The simultaneous coordination of
4
2
2
bridged by fumarato ligand into 1D polymeric chains
and those in the latter are simultaneously inter-linked by
hydroxo and fumarato ligands to generate a 3D open
framework.
2. Experimental
All chemicals of reagent grade were commercially
available and used without further purification. The C
and H microanalyses were performed with a Heraeus
ÃCorresponding author. Fax: +574-87600747.
E-mail address: zhengcm@nbu.edu.cn (Y.-Q. Zheng).
0022-4596/$ - see front matter r 2003 Elsevier Inc. All rights reserved.
doi:10.1016/j.jssc.2003.11.008

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1353
Rapid-CHNO elemental analyzer. The magnetic sus-
ceptibility was measured on powdered sample
effects. SHELXS-97 and SHELXL-97 programs [15,16]
were used for structure solution and refinement. Using
direct methods the structures were solved. Subsequently
difference Fourier syntheses enabled all non-hydrogen
atoms to be located. All hydrogen atoms of the
Fumarato groups were geometrically generated while
the remaining hydrogen atoms were located from the
successive difference Fourier syntheses after several
cycles of refinement. Finally, all non-hydrogen atoms
were refined with anisotropic displacement parameters
by a full-matrix least-squares technique and hydrogen
atoms with isotropic displacement parameters. Detailed
information about the crystal data and structure
determination is summarized in Table 1. Atomic
coordinates, and equivalent isotropic displacement
parameters are listed in Tables 2 and 3. The selected
interatomic distances and bond angles are given
in Tables 4 and 5. Crystallographic data (excluding
structure factors) for the structures in this paper
have been deposited with Cambridge Crystallographic
Data Centre as supplementary publication nos.
CCDC 214504 (C4H10CoO8) and CCDC 214505
(C8H18Co3O16). Copies of the data can be obtained,
free of charge, on application to CCDC, 12 Union
Road, Cambridge CB2 1EZ, UK (fax: +44 1223 336033
or mailto:deposit@ccdc.cam.ac.uk).
a
(58.98 mg 1 and 70.98 mg 2) using a SQUID magnet-
ometer (Quantum Design Model MPMS-7) in a
temperature range 5pTðKÞp300 with an applied field
of 10,000 G and diamagnetic corrections were estimated
from Pascal’s constants [14]. The combined TG/DTA
measurements were carried out from room temperature
to 600ꢀC on preweighed samples (5.24 mg 1, 7.01 mg 2)
in a flowing nitrogen atmosphere using a Seiko
Exstar6000 TG/DTA6300 equipment at a heating rate
of 10ꢀC/min.
3. Syntheses
3.1. Co(H2O)4(C4H2O4) 1
Dropwise addition of 6.0 mL (1 M) Na2CO3 to a
stirred aqueous solution of CoCl2 Á 6H2O (0.59 g,
2.50 mmol)
in
4 mL
H2O
produced
violet
CoðOHÞ2À2xðCO3ÞxÁyH2O precipitate, which was then
centrifugalized and washed with double-distilled water
until no ClÀ anions were detectable in the supernatant.
The fresh precipitate was subsequently added to a
stirred solution of 0.29 g (2.50 mmol) fumaric acid and
0.17 g (2.50 mmol) imidazole in 50 mL CH3OH/H2O (1:1
v/v). The mixture was further stirred for half an hour.
After the insoluble solid was filtered off, the rose-
colored filtrate (pH=7.29) was maintained at 50ꢀC and
rose-colored crystals were formed in a few hours. Yields:
40% based on the initial CoCl2 Á 6H2O input. Anal. Calc.
for C4H10CoO8 (%): C, 19.61; H, 4.11. Found: C, 19.58;
H, 4.07.
5. Results and discussion
5.1. Syntheses and thermal analyses
Both the title coordination polymers are syn-
thesized under mild conditions, similar to the two
cobalt succinato polymers Co(H2O)4(C4H4O4) [12c]
and [Co3(H2O)4(OH)2(C4H4O4)2] Á 6H2O reported ear-
lier by us [3,12b]. Ferey and co-workers prepared
two additional cobalt succinato polymers Co5(OH)2
(C4H4O4) and Co4(OH)2(H2O)2(C4H4O4)3 Á 2H2O by
using hydrothermal techniques [7c,7d]. The present
reaction of the freshly precipitated Co(OH)2À2x
(CO3)x Á yH2O, fumaric acid and imidazole in CH3OH/
H2O at pH=7.29 was originally aimed at the prepara-
tion of ternary Co imidazole fumarato complex, which
serendipitously afforded a new cobalt polymeric chain
compound, Co(H2O)4(C4H2O4) 1. This fact indicates
that 1 may be obtained in the absence of imidazole. To
our surprise, the reaction of fresh Co(OH)2À2x
(CO3)x Á yH2O precipitate and fumaric acid in CH3OH/
H2O yielded a new cobalt hydroxide fumarato coordi-
nation polymer, [Co3(H2O)4(OH)2(C4H2O4)2] Á 2H2O 2
at pH=5.46. The reproducible experiments suggest that
imidazole may serve as a templating reagent for the
formation of 1.
3.2. [Co3(H2O)4(OH)2(C4H2O4)2] Á 2H2O 2
A synthetic procedure analogous to 1 was used except
that no imidazole was added. A rose-colored filtrate
(pH=5.46) was allowed to stand at 50ꢀC and rose-
colored crystals grew in a few hours. After the
separation of the product, the pH value of the filtrate
was equal to 4.83. Yields: 35% based on the initial
CoCl2 Á 6H2O input. Anal. Calc. for C8H18Co3O16 (%):
C, 17.57; H, 3.31. Found: C, 17.52; H, 3.29.
4. X-ray crystallography
The cell determination and X-ray data collection were
carried out in a Bruker P4 diffractometer with graphite-
monochromated MoKa radiation (l ¼ 0:71073 A). The
lattice parameters were refined from the 2W values
(10–25ꢀ) of 25 carefully centered reflections. The data
with 2Wmax ¼ 55ꢀ were collected at 293 K using the W22W
scan technique and corrected for Lp and absorption
Over the temperature range 63–185ꢀC, 1 undergoes a
sharp endothermic dehydration with the observed

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1354
Table 1
Summary of crystal data, data collection, structure solution and refinement details for 1 and 2
Compounds
1
2
Empirical formula
Formula weight
Description
Crystal size (mm)
Temperature (K)
Crystal system
Space group
Unit-cell dimensions
a (A)
C4H10CoO8
245.05
C8H18Co3O16
547.02
Rose-colored block
0.22 Â 0.11 Â 0.11
293(2)
Rose-colored block
0.20 Â 0.09 Â 0.07
293(2)
Monoclinic
P21=c
Monoclinic
P21=c
7.493(1)
6.618(1)
8.172(2)
15.578(3)
96.30(3)
837.4(3)
2
b (A)
c (A)
14.377(1)
7.708(1)
99.54(1)
b (deg)
Volume (A3)
Z
818.9(2)
4
1.988
Dcalc (g cmÀ3
)
2.169
550
3.022
Fð000Þ
500
2.111
m (mmÀ1
)
Absorption correction
Min. and max. transmission
y range (deg)
Refinement method
Reflections collected
Empirical
0.396, 0.465
2.76–27.48
Full-matrix least-squares on F2
2471
Empirical
0.309, 0.420
2.63–27.49
2749
Independent reflections (Rint
Data/restraints/parameters
Goodness of fit on F2
)
1877(0.0298)
1487/0/152
1.028
1927(0.0446)
1442/0/154
0.983
a
R1; wR2 ½IX2sðIފ
0.0304, 0.0669
0.0465, 0.0722
0.0048(9)
0.0307, 0.0000
0.275, À0.394
0.0360, 0.0663
0.0602, 0.0732
0.0010(5)
R1; wR2 (all data)a
Extinction coefficients
A; B values in weighting schemeb
0.0258, 0.0000
0.483, À0.493
drmax; drmin (e AÀ3
P
)
P
2
2 1=2
a wR2¼ ½ wðFo22Fc2Þ = wðFo2Þ Š
:
2
À1
b w ¼ ½s2ðFo2Þ þ ðAPÞ þ BPŠ with P ¼ ðFo2 þ 2Fc2Þ=3:
Table 2
Atomic parameters and equivalent isotropic thermal parameters (A2) for non-hydrogen atoms in 1
Atom
Wyckoff site
x
y
z
Ueq
Co
4e
4e
4e
4e
4e
4e
4e
4e
4e
4e
4e
4e
4e
1.08085(4)
0.8850(2)
0.7314(2)
0.2670(2)
0.5276(2)
1.0239(3)
0.8911(3)
1.1414(3)
1.2811(3)
0.7686(3)
0.6761(3)
0.5334(3)
0.4391(3)
0.86039(2)
0.8350(1)
0.9681(1)
0.8760(1)
0.8665(2)
1.0017(1)
0.8438(1)
0.7175(1)
0.8725(1)
0.8907(2)
0.8600(2)
0.9034(2)
0.8793(2)
0.79994(4)
0.5762(2)
0.5505(2)
0.0327(2)
0.0161(1)
0.0227(4)
0.0266(4)
0.0224(4)
0.0304(4)
0.0274(4)
0.0206(4)
0.0249(4)
0.0220(4)
0.0191(5)
0.0220(5)
0.0209(5)
0.0194(5)
O(1)
O(2)
O(3)
O(4)
O(5)
O(6)
O(7)
O(8)
C(1)
C(2)
C(3)
C(4)
À0.0702(2)
0.7832(3)
0.9687(2)
0.8105(3)
0.6359(2)
0.4937(3)
0.3159(3)
0.2317(3)
0.0504(3)
weight loss of 29.9% corresponding well to the
calculated value of 29.40% for four moles of H2O
molecules per formula unit. The formed anhydrous
cobalt fumarate ‘‘Co(C4H2O4)’’ experiences an exothermic
phase transformation at 280ꢀC. Upon further heating,
the anhydrous intermediate starts an endothermic
decomposition at 380ꢀC and finishes at 464ꢀC, at which
temperature an additional weight loss reaches 40.4% in
good agreement with the calculated value of 40.01% for
one mole of fumaric anhydride (C4H2O3), and the
residue collected at 600ꢀC is identified to
be CoO. When heated up to 600ꢀC, compound 2

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1355
Table 3
Atomic parameters and equivalent isotropic thermal parameters (A2) for non-hydrogen atoms in 2
Atom
Wyckoff site
x
y
z
Ueq
Co(1)
Co(2)
O(1)
O(2)
O(3)
O(4)
O(5)
O(6)
O(7)
O(8)
C(1)
C(2)
C(3)
C(4)
4e
2a
4e
4e
4e
4e
4e
4e
4e
4e
4e
4e
4e
4e
0.51578(7)
1
0.81829(6)
1
0.02371(2)
0
0.0141(1)
0.0141(2)
0.0195(5)
0.0218(6)
0.0212(6)
0.0211(6)
0.0140(5)
0.0256(6)
0.0224(6)
0.0364(8)
0.0173(7)
0.0216(8)
0.0212(8)
0.0159(7)
0.6794(3)
1.0027(4)
1.0397(4)
1.3624(3)
0.6877(3)
0.7255(5)
0.3406(4)
0.4925(5)
0.8685(5)
0.9321(5)
1.1093(5)
1.1729(5)
0.8661(3)
0.8623(3)
0.7219(3)
0.7595(3)
0.9850(3)
0.6249(4)
0.6601(4)
0.0902(5)
0.8459(4)
0.7959(5)
0.8293(5)
0.7669(4)
0.1446(1)
0.1152(1)
0.4330(1)
0.4073(1)
À0.0361(2)
0.0088(2)
0.0960(2)
0.2370(2)
0.1650(2)
0.2563(2)
0.2978(2)
0.3871(2)
Note: Ueq is defined as one-third of the trace of the orthogonalized Uij tensor.
Table 4
Selected interatomic distances (A) and bond angles (deg) for 1
Co–O(1)
Co–O(3)#2
Co–O(5)
Co–O(6)
Co–O(7)
2.103(2)
2.094(2)
2.075(2)
2.094(2)
2.103(2)
Co–O(8)
2.123(2)
1.274(3)
1.244(3)
1.496(3)
1.313(4)
C(3)–C(4)
C(4)–O(3)
C(4)–O(4)
1.499(3)
1.275(3)
1.242(3)
C(1)–O(1)
C(1)–O(2)
C(1)–C(2)
C(2)–C(3)
O(1)/Co/O(7)
O(1)/Co/O(8)
O(3)#2/Co/O(1)
O(3)#2/Co/O(7)
O(3)#2/Co/O(8)
O(5)/Co/O(1)
O(5)/Co/O(3)#2
O(5)/Co/O(6)
88.78(7)
89.53(7)
175.14(7)
87.87(7)
93.76(7)
90.61(8)
92.83(8)
89.80(8)
O(5)/Co/O(7)
O(5)/Co/O(8)
O(6)/Co/O(1)
O(6)/Co/O(3)#2
O(6)/Co/O(7)
O(6)/Co/O(8)
O(7)/Co/O(8)
O(1)/C(1)/O(2)
178.44(8)
92.34(8)
92.07(7)
84.52(7)
91.65(8)
177.31(8)
86.22(8)
124.2(2)
C(2)/O(2)/C(1)
C(2)/O(1)/C(1)
C(2)/C(1)/C(3)
C(2)/C(3)/C(4)
O(3)/C(4)/O(4)
C(3)/O(4)/C(4)
C(3)/O(3)/C(4)
119.3(2)
116.5(2)
121.9(2)
124.8(2)
124.8(2)
120.3(2)
114.9(2)
Hydrogen bonding contacts
D–H
d(D–H)
0.77
0.83
0.73
0.85
0.81
0.80
0.85
0.78
d(H?A)
2.18
1.93
+(D–H?A)
d(D–H?A)
2.932
2.636
A
O(5)–H(5A)
O(5)–H(5B)
O(6)–H(6A)
O(6)–H(6B)
O(7)–H(7A)
O(7)–H(7B)
O(8)–H(8A)
O(8)–H(8B)
168
143
179
170
165
171
160
171
O6#3
O2
1.97
1.87
2.703
2.710
O1#4
O4#5
O8#4
O3#6
O4#7
O2#8
2.07
2.03
2.862
2.818
1.86
1.93
2.677
2.699
Symmetry codes: #1, x À 1; y; z À 1; #2, x þ 1; y; z þ 1; #3, Àx þ 2; Ày þ 2; Àz þ 2; #4, x; Ày þ 3=2; z þ 1=2; #5, x; y; z þ 1; #6, x þ 1; Ày þ 3=2; z þ
1=2; #7, x þ 1; y; z þ 1; #8, Àx þ 2; Ày þ 2; Àz þ 1:
experiences three endothermic processes with the peaks
on the DTA curve centered at 120ꢀC, 175ꢀC and 424ꢀC,
respectively. The weight loss of 20.0% over 50–245ꢀC
agrees well to the calculated value of 19.76% for six
moles of H2O molecules per formula unit, and the
weight loss of 40.6% over 330–500ꢀC is slightly larger
than the value of 39.14% calculated for one mole of
H2O molecule and two moles of fumaric anhydride
(C4H2O3). The residue gathered at 600ꢀC is verified to
be CoO.
5.2. Crystal structures
5.2.1. Co(H2O)4(C4H2O4) 1
Compound 1 crystallizes isostructurally with the
monoclinic M(H2O)4(C4H4O4) with M=Ni(II), Co(II)
and (C4H4O4)2À=succinate anion [12c,12d]. The Co
atoms in 1 are bridged by bis-monodentate fumarate
anions to generate 1D linear chains formulated as
1
½CoðH2OÞ4ðC4H2O4Þ2=2Š as shown in Fig. 1. The
N
octahedral coordination environment around the Co

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1356
Table 5
Selected interatomic distances (A) and bond angles (deg) for 2
Co(1)–O(1)
Co(1)–O(4)#4
Co(1)–O(5)
Co(1)–O(5)#5
Co(1)–O(6)
Co(1)–O(7)
Co(2)–O(2)
2.103(2)
2.078(2)
2.062(2)
2.120(3)
2.133(3)
2.137(3)
2.117(2)
Co(2)–O(2)#1
Co(2)–O(3)#2
Co(2)–O(3)#3
Co(2)–O(5)
Co(2)–O(5)#1
C(1)–O(1)
2.117(2)
2.123(2)
2.123(2)
2.085(2)
2.085(2)
1.268(4)
1.250(4)
C(1)–C(2)
C(2)–C(3)
C(3)–C(4)
C(4)–O(3)
C(4)–O(3)
1.495(4)
1.304(5)
1.500(4)
1.249(4)
1.261(4)
C(1)–O(2)
O(1)/Co(1)/O(5)#5
O(1)/Co(1)/O(6)
O(1)/Co(1)/O(7)
O(4)#4/Co(1)/O(1)
O(4)#4/Co(1)/O(5)#5
O(4)#4/Co(1)/O(6)
O(4)#4/Co(1)/O(7)
O(5)/Co(1)/O(1)
O(5)/Co(1)/O(4)#4
O(5)/Co(1)/O(5)#5
O(5)/Co(1)/O(6)
O(5)/Co(1)/O(7)
O(5)#5/Co(1)/O(6)
92.72(9)
87.6(1)
84.1(1)
172.9(1)
93.3(1)
86.5(1)
91.9(1)
81.52(9)
92.8(1)
85.9(1)
92.4(1)
174.7(1)
178.3(1)
O(5)#5/Co(1)/O(7)
O(6)/Co(1)/O(7)
91.4(1)
90.4(1)
180
O(5)#1/Co(2)/O(2)
O(5)#1/Co(2)/O(2)#1
O(5)#1/Co(2)/O(3)#2
O(5)#1/Co(2)/O(3)#3
O(1)/C(1)/C(2)
96.51(9)
83.49(9)
83.39(9)
90.61(9)
116.2(3)
125.4(3)
118.4(3)
122.3(3)
123.9(3)
126.1(3)
119.2(3)
114.7(3)
O(2)/Co(2)/O(2)#1
O(2)/Co(2)/O(3)#2
O(2)/Co(2)/O(3)#3
O(2)#1/Co(2)/O(3)#2
O(2)#1/Co(2)/O(3)#3
O(3)#3/Co(2)/O(3)#2
O(5)/Co(2)/O(2)
91.56(9)
88.44(9)
88.44(9)
91.56(9)
180
O(2)/C(1)/O(1)
O(2)/C(1)/C(2)
C(2)/C(3)/C(4)
96.51(9)
83.49(9)
90.61(9)
83.39(9)
C(3)/C(2)/C(1)
O(5)/Co(2)/O(2)#1
O(5)/Co(2)/O(3)#2
O(5)/Co(2)/O(3)#3
O(5)/Co(2)/O(5)#1
O(3)/C(4)/O(4)
O(3)/C(4)/C(3)
O(4)/C(4)/C(3)
Hydrogen bonding contacts
D–H
d(D–H)
0.82
0.78
d(H?A)
1.97
2.08
+DHA
167
172
d(D–H?A)
2.797
2.850
A
O(6)–H(6A)
O(6)–H(6B)
O3#3
O6#8
O2#9
O8#10
O4#6
O1#11
O(7)–H(7A)
O(7)–H(7B)
0.74
0.85
2.10
1.93
168
177
2.722
2.694
O(8)–H(8A)
O(8)–H(8A)
0.85
0.85
2.10
1.94
155
150
2.893
2.711
Symmetry codes: #1, Àx þ 2; Ày þ 2; Àz; #2, Àx þ 2; 1=2 þ y; Àz þ 1=2; #3, x; Ày þ 3=2; z À 1=2; #4, x À 1; Ày þ 3=2; z À 1=2; #5, Àx þ 1; Ày þ
2; Àz; #6, Àx þ 2; y À 1=2; Àz þ 1=2; #7, x þ 1; Ày þ 3=2; z þ 1=2; #8, Àx þ 1; Ày þ 1; Àz; #9, x À 1; y; z; #10, Àx þ 1; y þ 1=2; Àz þ 1=2; #11, x; y À
1; z:
bonds exist, i.e., (1) between aqua oxygen and aqua
oxygen atoms with d(O?O)=2.862, 2.932 A, (2)
between aqua oxygen and coordinating carboxylato
oxygen atoms with d(O?O)=2.703, 2.818 A and (3)
between aqua oxygen and uncoordinating oxygen atoms
with d(O?O)=2.699, 2.710 A (Table 4). Each poly-
meric chain is found to be hydrogen bonded to five
neighbors, which suggests that the supramolecular
assembly of the polymeric chains is due to the extensive
interchain hydrogen-bonding interactions. The fumar-
ato ligand exhibits the usual bond distances and angles
[13] and the carboxylato groups are found to be rotated
away by 13.2(4)ꢀ and 47.4(3)ꢀ, respectively, from the
plane defined by the skeleton carbon atoms due to the
intrachain hydrogen bonds.
Fig. 1. Ortep view of
1
N
displacement ellipsoids are drawn at 45% probability level (symmetry
codes: see Table 4).
a
section of the polymeric chain
with the atomic labelling for 1. The
½CoðH2OÞ4ðC4H2O4Þ2=2
Š
atoms is defined by six O atoms of four aqua ligands and
two fumarate anions. The Co–O bond distances fall in
the region 2.075–2.123 A and the cisoid and transoid
O–Co–O bond angles over the ranges 84.52–93.76ꢀ and
175.14–178.44ꢀ, respectively (Table 4), indicating a
5.2.2. [Co3(H2O)4(OH)2(C4H2O4)2] Á 2H2O 2
slight deviation of the coordination polyhedron from
1
The asymmetric unit of 2 contains 14 non-hydrogen
atoms, of which two are the crystallographically distinct
Co atoms, namely, Co(1) and Co(2) (Fig. 2). The Co(1)
an ideal one. The polymeric ½CoðH2OÞ4ðC4H2O4Þ2=2
Š
N
chains run parallel to [101] and display two relatively
strong intrachain hydrogen bonds between the aqua
oxygen and uncoordinating carboxylate oxygen atoms
with d(O?O)=2.636, 2.677 A (Table 4). Within the
crystal structure three groups of interchain hydrogen
atoms are in
a significantly distorted octahedral
environment defined by two oxygens (O(1) and O(4))
of different fumarate anions, two aqua oxygens (O(6)
and O(7)) and two m3 hydroxo oxygens O(5) at the cis

ARTICLE IN PRESS
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1357
Fig. 2. Ortep view of the coordination mode of fumarato ligand and
the atomic labelling for 2. The displacement ellipsoids are drawn at
45% probability level (symmetry codes: see Table 5).
Fig. 3. 1D cobalt oxide chain generated from the edge-shared Co2O10
bi-octahedra bridged by the CoO6 octahedra in 2.
Fig. 4. Crystal structure of 2.
positions with the Co–O bond distances in the region
2.078–2.137 A (Table 5). Two such octahedra are
condensed through two m3 hydroxide anions to form
edge-shared bi-octahedra, which are bridged by the
CoO6 octahedra centered by the Co(2) atoms to
generate cobalt oxide chain, which extends infinitely
along the [100] direction (Fig. 3). The Co(2) atoms are
coordinated by four oxygen atoms of different fumarate
anions and two m3 hydroxo oxygens at the trans
positions and the Co–O bond distances vary from
2.085 to 2.117 A. The fumarate anions have the usual
bond distances and angles [13], but the carboxylato
groups are rotated away from the skeleton carbon plane
by 21.3(5)ꢀ and 29.5(4)ꢀ, respectively. Through the bis-
bidentate fumarate anions, the cobalt oxide chains are
inter-linked into 3D open framework with rhombic
tunnels propagating in the [100] direction (Fig. 4). The
lattice H2O molecules are located in the tunnels and
hydrogen bonded to two carboxylato oxygen atoms
with d(O?O)=2.711, 2.893 A (Table 5). The present
structure displays a close similarity to a cobalt succinato
coordination polymer ½Co3ðH2OÞ4ðOHÞ2ðC4H4O4Þ2ŠÁ
6H2O; where the longer succinato ligands inter-link
cobalt oxide chains to give larger rhombic tunnels to
accommodate more water molecules [12b]. In addition,
the cobalt oxide chains in the present polymer are zigzag
ones and those in the latter exhibit a mirror symmetry
bisecting the edge-shared bi-octahedra along the chains.
Different from fumarato ligands in 2, the non-hydrogen
atoms of the succinato ligands are co-planar in
the previously reported ½Co3ðH2OÞ4ðOHÞ2ðC4H4O4Þ2ŠÁ
6H2O [12b].
According to the above description, it is now clear
that the similarity of 1 to Co(H2O)4(C4H4O4) [12c] and 2
to [Co3(H2O)4(OH)2(C4H4O4)2] Á 6H2O [12b] is due to
the similar structure of the linear dicarboxylato groups
of the fumarate (C4H2O4)2À and succinate (C4H4O4)2À
anions. Obviously, less conformational flexibility of the
fumarate anions due to the C ¼ C double bonds will
not form cobalt coordination polymers with similar

ARTICLE IN PRESS
Y.-Q. Zheng, H.-Z. Xie / Journal of Solid State Chemistry 177 (2004) 1352–1358
1358
Acknowledgments
This work is supported by the National Natural
Science Foundation of China (20072022), the Ningbo
Minicipal Key Doctor’s Funds (2003A61014) and the
Ningbo Municipal Natural Science Foundation
(01J20130-1). The authors are indebted to Mr. Jian-Li
Lin for X-ray data collection.
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to
the
hydrothermally
prepared
Co5ðOHÞ2ðC4H4O4Þ and Co4ðOHÞ2ðH2OÞ2ðC4H4O4Þ3Á
2H2O; both of which are reported to feature two-
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¨