Catena-Poly[[aqua(2,2′-bipyridine-κ2N,N′) cadmium(II)]-μ-4-carboxyl-atophenoxyacetato-κO:O4,O 4′]

Article abstract of DOI:10.1107/S0108270106026783

In the title compound, [Cd(C₉H₆O₅)(C ₁₀H₈N₂)(H₂O)]_n, the Cd^II atom is coordinated in a distorted octahedral fashion by two carboxylate groups (one in a monodentate and one in a bidentate fashion) from two 4-carboxylatophenoxyacetate anions, two N atoms from a 2,2′-bipyridine ligand and one aqua ligand. The structure is a helix with a long pitch of 16.441 (5) A. A three-dimensional supramolecular network is further constructed through π-π stacking and hydrogen-bonding interactions between the helices.

Full text of DOI:10.1107/S0108270106026783

metal-organic compounds
Acta Crystallographica Section C
Crystal Structure
Communications
sionality and may provide potential supramolecular recogni-
tion sites for ꢀ±ꢀ stacking interactions (Chen et al., 2002;
Zhang et al., 2004) to form multi-stranded helices. Using
4-carboxyphenoxyacetic acid (H2cpoa) and 2,20-bipy, we have
hydrothermally prepared the title compound, [Cd(cpoa)-
(2,20-bipy)(H2O)]n, (I), which is a new neutral in®nite CdII±
dicarboxylate helical coordination polymer. The structure is
reported in this paper.
The asymmetric unit of (I) contains one CdII atom, one
cpoa2 ligand, one 2,20-bipy ligand and one aqua ligand
(Fig. 1). The Cd atom is coordinated by three O atoms from
one monodentate and one bidentate carboxylate group of two
cpoa2 ligands, the aqua ligand, and two N atoms from the
2,20-bipy ligand to furnish a distorted octahedral geometry.
The Cd1ÐO3i and Cd1ÐO4i bonds are longer than the Cd1Ð
O1 bond (see Table 1 for distances and symmetry codes). Each
pair of adjacent CdII atoms are bridged by cpoa2 ligands to
form a chiral helical chain running along the 21 axis in the c
ISSN 0108-2701
catena-Poly[[aqua(2,20-bipyridine-
j2N,N0)cadmium(II)]-l-4-carboxyl-
0
atophenoxyacetato-j3O:O4,O4 ]
Yan Yang,a Ming-Hua Zeng,b Fa-Yan Mengb and Hong
Liangb*
aCollege of Chemistry and Chemical Engineering, Central South University,
Changsha, Hunan 410000, People's Republic of China, and bSchool of Chemistry
and Chemical Engineering, Guangxi Normal University, Guilin, 541004, People's
Republic of China
Correspondence e-mail: zmh@mailbox.gxnu.edu.cn
Ê
direction with a pitch of 16.441 (5) 0A; this is longer than the
Ê
Received 31 May 2006
Accepted 11 July 2006
Online 11 August 2006
pitch of 11.25 (1) A in [Cu(ipa)(2,2 -bipy)]n.2nH2O (H2ipa is
isophthalic acid; Chen et al., 2002) because the cpoa2 dianion
is larger than the ipa2 dianion. These chains are decorated
with 2,20-bipy ligands, positioned alternately on two sides and
pointing outwards, as depicted in Fig. 2. The benzene rings of
the cpoa2 ions at each side of the helix are arranged in a
In the title compound, [Cd(C9H6O5)(C10H8N2)(H2O)]n, the
CdII atom is coordinated in a distorted octahedral fashion by
two carboxylate groups (one in a monodentate and one in a
bidentate fashion) from two 4-carboxylatophenoxyacetate
anions, two N atoms from a 2,20-bipyridine ligand and one
aqua ligand. The structure is a helix with a long pitch of
Ê
16.441 (5) A. A three-dimensional supramolecular network is
further constructed through ꢀ±ꢀ stacking and hydrogen-
bonding interactions between the helices.
Comment
It has been noted that employment of ¯exible or V-shaped
exobidentate organic bridges can improve the helicity of
polymeric chains (Ye et al., 2005). Therefore, we assumed that
Figure 1
A view of (I), shown with 30% probability displacement ellipsoids.
1
[Symmetry code: (i) x + , y + 1, z 12.]
2
the 4-carboxylatophenoxyacetate (cpoa2 ) anion, as a multi-
dentate ligand with two different carboxylate groups, one at a
¯exible site, may be useful in the formation of single-stranded
helical chains in the presence of aromatic chelate ligands, such
as 2,20-bipyridine (2,20-bipy) and 1,10-phenanthroline (phen).
These ligands are important in maintaining the one-dimen-
Figure 2
The chiral helical chain of (I).
m392 # 2006 International Union of Crystallography
DOI: 10.1107/S0108270106026783
Acta Cryst. (2006). C62, m392±m394

metal-organic compounds
adjusted to 6 with triethylamine. The solution was sealed in a 15 ml
Te¯on-lined stainless steel bomb and held at 413 K for 96 h. The
bomb was then allowed to cool naturally to room temperature.
Colorless prismatic crystals were ®ltered off, washed with water and
dried at room temperature (yield 58%).
Crystal data
[Cd(C9H6O5)(C10H8N2)(H2O)]
Mr = 480.74
Orthorhombic, P212121
Z = 4
Dx = 1.804 Mg m
Mo Kꢁ radiation
ꢂ = 1.27 mm
T = 293 (2) K
Prism, colorless
0.37 Â 0.21 Â 0.17 mm
3
1
Ê
a = 6.799 (2) A
Ê
b = 15.834 (5) A
Ê
c = 16.441 (5) A
3
Ê
V = 1769.9 (9) A
Data collection
Bruker APEX area-detector
diffractometer
' and ! scans
Absorption correction: multi-scan
(SADABS; Sheldrick, 1996)
Tmin = 0.650, Tmax = 0.812
10675 measured re¯ections
3866 independent re¯ections
3417 re¯ections with I > 2ꢃ(I)
Rint = 0.028
ꢄmax = 27.1ꢀ
Figure 3
The two-dimensional layer of (I), formed through hydrogen bonds
(dashed lines). H atoms have been omitted.
Re®nement
Re®nement on F2
R[F2 > 2ꢃ(F2)] = 0.026
wR(F2) = 0.050
S = 1.06
3866 re¯ections
262 parameters
H atoms treated by a mixture of
independent and constrained
re®nement
w = 1/[ꢃ2(F2o) + (0.0231P)2]
where P = (F2o + 2Fc2)/3
(Á/ꢃ)max = 0.001
3
Ê
Áꢅmax = 0.56 e A
3
Ê
0.27 e A
Áꢅmin
=
Absolute structure: Flack (1983),
1617 Friedel pairs
Flack parameter: 0.36 (2)
Table 1
Selected geometric parameters (A, ).
ꢀ
Ê
Cd1ÐO1
Cd1ÐO4i
Cd1ÐN1
2.206 (2)
2.295 (2)
2.328 (2)
Cd1ÐO1W
Cd1ÐN2
Cd1ÐO3i
2.336 (3)
2.342 (2)
2.513 (2)
O1ÐCd1ÐO4i
O1ÐCd1ÐN1
O4iÐCd1ÐN1
O1ÐCd1ÐO1W
O4iÐCd1ÐO1W
N1ÐCd1ÐO1W
O1ÐCd1ÐN2
O4iÐCd1ÐN2
99.5 (1)
99.8 (1)
159.4 (1)
88.7 (1)
94.7 (1)
92.86 (10)
169.70 (9)
90.05 (8)
N1ÐCd1ÐN2
O1WÐCd1ÐN2
O1ÐCd1ÐO3i
O4iÐCd1ÐO3i
N1ÐCd1ÐO3i
O1WÐCd1ÐO3i
N2ÐCd1ÐO3i
70.25 (9)
94.43 (9)
96.09 (8)
54.03 (7)
116.52 (9)
148.72 (9)
86.33 (8)
1
2
Symmetry code: (i) x ‡ 12; y ‡ 1; z
.
Figure 4
The three-dimensional network of (I), formed through hydrogen bonds
and ꢀ±ꢀ stacking. H atoms have been omitted.
Table 2
Hydrogen-bond geometry (A, ).
ꢀ
Ê
parallel fashion, with a vertical inter-ring distance of
Ê
5.04 (1) A; adjacent chiral helices are connected into a two-
DÐHÁ Á ÁA
DÐH
HÁ Á ÁA
DÁ Á ÁA
DÐHÁ Á ÁA
O1WÐH1AÁ Á ÁO3ii
0.89 (4)
0.76 (4)
1.92 (4)
2.09 (4)
2.773 (3)
2.787 (4)
161 (3)
154 (4)
O1WÐH1BÁ Á ÁO2iii
dimensional network through hydrogen bonds involving aqua
ligands (Table 2 and Fig. 3). The two-dimensional network is
extended into a three-dimensional supramolecular network by
ꢀ±ꢀ stacking through intercalation of the 2,20-bipy rings [the
Symmetry codes: (ii) x ‡ 32; y ‡ 1; z 12; (iii) x ‡ 1; y; z.
Ê
face-to-face distance is 3.42 (1) A; Fig. 4].
The water H atoms were located in difference Fourier maps and
re®ned freely. All other H atoms were positioned geometrically and
re®ned using a riding model, with CÐH distances of 0.97 (CH2) or
Experimental
Ê
0.93 A (aromatic) and Uiso(H) values of 1.2Ueq(C).
2,20-Bipyridine (0.157 g, 1 mmol) and cadmium nitrate (0.308 g,
1 mmol) were dissolved in a hot aqueous solution of 4-carboxy-
phenoxyacetic acid (0.196 g, 1 mmol) and the pH of the solution was
Data collection: SMART (Bruker, 2001); cell re®nement: SAINT
(Bruker, 2001); data reduction: SAINT; program(s) used to solve
structure: SHELXS97 (Sheldrick, 1997); program(s) used to re®ne
ꢁ
Acta Cryst. (2006). C62, m392±m394
Yang et al.
[Cd(C9H6O5)(C10H8N2)(H2O)] m393

metal-organic compounds
structure: SHELXL97 (Sheldrick, 1997); molecular graphics:
ORTEPII (Johnson, 1976); software used to prepare material for
publication: SHELXL97.
References
Bruker (2001). SAINT (Version 6.45) and SMART (Version 5.0). Bruker AXS
Inc., Madison, Wisconsin, USA.
Chen, X.-M. & Liu, G.-F. (2002). Chem. Eur. J. 8, 4811±4817.
Flack, H. D. (1983). Acta Cryst. A39, 876±881.
Johnson, C. K. (1976). ORTEPII. Report ORNL-5138. Oak Ridge National
Laboratory, Tennessee, USA.
È
Sheldrick, G. M. (1996). SADABS. University of Gottingen, Germany.
Sheldrick, G. M. (1997). SHELXS97 and SHELXL97. University of
The authors acknowledge ®nancial support by the NSFC
(grant Nos. 30460153 and 20561001) and the Natural Science
Foundation of Guangxi Province (grant No. 0447019).
È
Gottingen, Germany.
Supplementary data for this paper are available from the IUCr electronic
archives (Reference: OB3012). Services for accessing these data are
described at the back of the journal.
Ye, B.-H., Tong, M.-L. & Chen, X.-M. (2005). Coord. Chem. Rev. 249, 545±565.
Zhang, L.-Y., Zeng, M.-H., Sun, X.-Z., Shi, Z., Feng, S.-H. & Chen, X.-M.
(2004). J. Mol. Struct. 679, 181±184.
ꢁ
m394 Yang et al. [Cd(C9H6O5)(C10H8N2)(H2O)]
Acta Cryst. (2006). C62, m392±m394