Poly[(μ3-benzene-1,4-diacetato)[μ2- 1,4-bis(1,2,4-triazol-1-yl)butane]-cadmium(II)]: Self assembly into a three-dimensional supramolecular framework based on [Cd(μ3- benzene- 1,4-diacetate)] double chains

Article abstract of DOI:10.1107/S0108270111016507

The title compound, [Cd(C₁₀H₈O₄)(C ₈H₁₂N₆)] n, crystallizes with an asymmetric unit comprising a divalent Cd^II atom, a benzene-1,4-diacetate (PBEA^2-) ligand and a comp

Full text of DOI:10.1107/S0108270111016507

metal-organic compounds
Acta Crystallographica Section C
Crystal Structure
Communications
orientations of its CH2 groups, 1,4-bis(1,2,4-triazol-1-yl)butane
(BTB) can adopt different conformations compared with the
corresponding 1,2,4-triazole ligand (Zhou et al., 2006; Wang,
Zhang et al., 2008; Liang et al., 2009; Zhu et al., 2009). We have
selected H2PBEA and BTB as organic linkers, generating the
title new CdII coordination polymer, [Cd(PBEA)(BTB)]n, (I),
the crystal structure of which we now report. We recently also
reported the structure of a polymorph of (I) (Wang et al.,
2011).
ISSN 0108-2701
Poly[(l3-benzene-1,4-diacetato)[l2-
1,4-bis(1,2,4-triazol-1-yl)butane]-
cadmium(II)]: self assembly into a
three-dimensional supramolecular
framework based on [Cd(l3-benzene-
1,4-diacetate)] double chains
Jun Wang,* Jian-Qing Tao and Xiao-Juan Xu
Department of Chemistry, Yancheng Teachers’ College, Yancheng 224002, People’s
Republic of China
Correspondence e-mail: wjyctu@gmail.com
Received 19 March 2011
Accepted 2 May 2011
Online 12 May 2011
Compound (I) crystallizes in the centrosymmetric triclinic
space group P1 with an asymmetric unit comprising a divalent
CdII cation, a dianionic PBEA2ꢀ ligand and a complete BTB
The title compound, [Cd(C10H8O4)(C8H12N6)]n, crystallizes
with an asymmetric unit comprising a divalent CdII atom, a
benzene-1,4-diacetate (PBEA2ꢀ) ligand and a complete 1,4-
bis(1,2,4-triazol-1-yl)butane (BTB) ligand. [Cd(PBEA)]n
double chains, arranged parallel to the c axis, are formed
through an exo-tridentate binding mode of the PBEA2ꢀ
ligands. These [Cd(PBEA)]n double chains are pillared by
tethering BTB ligands, in which the BTB shows a trans–trans–
trans conformation, to establish [Cd(PBEA)(BTB)]n two-
dimensional coordination polymer (4,4)-layer slab patterns.
The three-dimensional supramolecular architecture is formed
by C—Hꢁ ꢁ ꢁO hydrogen bonds and C—Hꢁ ꢁ ꢁꢀ interactions.
Comment
The design and synthesis of coordination polymers is an
attractive area of research, not only due to their diverse
topology and intriguing structures but also owing to their
potential applications in many fields (Eddaoudi et al., 2001;
Kitagawa et al., 2004; Ferey et al., 2005; Roy et al., 2009). The
mainstream method of constructing such coordination poly-
mers is to utilize dicarboxylate ligands, since carboxylate
groups have an excellent coordination capability and flexible
coordination patterns (Farnum et al., 2011). The disposition of
the donor groups around the periphery of the dicarboxylate
ligands, their metal coordination modes, and the different
types and flexibility of such ligands act synergistically to
provide access to vast numbers of structural topologies.
Owing to the increased flexibility of its two carboxylate
groups, benzene-1,4-diacetic acid (H2PBEA) may show a
variety of coordination modes and conformations (Pan et al.,
2003; Chen et al., 2006; Braverman & LaDuca, 2007; Wang,
Yang et al., 2008). Meanwhile, on the basis of the relative
Figure 1
A view of the local coordination of the CdII cations in (I), showing the
atom-numbering scheme. Displacement ellipsoids are drawn at the 50%
probability level. [Symmetry codes: (i) x, y, z ꢀ 1; (ii) x + 1, y, z ꢀ 1; (iii)
ꢀx + 2, ꢀy + 1, ꢀz.]
Figure 2
A single [Cd(PBEA)]n chain in (I), highlighting the presence of {Cd2O2}
rhomboid dimers.
Acta Cryst. (2011). C67, m173–m175
doi:10.1107/S0108270111016507
# 2011 International Union of Crystallography m173

metal-organic compounds
Figure 3
A view of the two-dimensional framework in (I).
ligand (Fig. 1). The coordination environment at the CdII
centre is best considered as a distorted {CdN2O5} pentagonal
bipyramid, with the axial positions occupied by trans N donor
atoms [N1 and N6ii; symmetry code: (ii) x + 1, y, z ꢀ 1] from
two BTB ligands. The equatorial sites are filled by four O-
atom donors [O1, O2, O3i and O4i; symmetry code: (i) x, y,
z ꢀ 1] from two chelating carboxylate termini from two
different PBEA2ꢀ ligands and a single O-atom donor [O3iii;
symmetry code: (iii) ꢀx + 2, ꢀy + 1, ꢀz] from a third PBEA2ꢀ
unit. The Cd1—N1 and Cd1—N6 bond lengths are 2.348 (4)
pattern of (I) can be represented as a (4,4) rectangular grid
motif. As determined by through-space Cdꢁ ꢁ ꢁCd distances, the
˚
apertures within the grid measure 11.27 ꢃ 14.66 A. Adjacent
[Cd(PBEA)(BTB)]n slabs stack in a simple AA pattern along
the b axis.
There are two types of weak hydrogen bond in the structure
of (I) (Fig. 4 and Table 1), namely two C—Hꢁ ꢁ ꢁO intralayer
hydrogen bonds involving carboxylate atom O1 and two C—
Hꢁ ꢁ ꢁO interlayer hydrogen bonds involving carboxylate atom
O2. In addition, an intralayer C—Hꢁ ꢁ ꢁꢀ interaction (Fig. 4) is
observed between C12—H12 and the centroid (Cg) of the
˚
and 2.326 (4) A, respectively, while the Cd—O bond lengths
˚
vary from 2.317 (4) to 2.551 (4) A. The average Cd—O and
˚
˚
C3–C8 ring, with C12ꢁ ꢁ ꢁCg = 3.752 (7) A, H12ꢁ ꢁ ꢁCg = 2.88 A
Cd—N distances in (I) are comparable with those in
previously reported Cd-based compounds (Liu et al., 2008)
and in the polymorph of (I) (Wang et al., 2011), in which a very
similar coordination geometry about the Cd atom is found.
[Cd(PBEA)]n double chains (Fig. 2), arranged parallel to
the c axis, are formed through an exo-tridentate binding mode
of the PBEA2ꢀ ligands. Within these chains are embedded
{Cd2O2} rhomboid subunits constructed by the chelating/
bridging carboxylate end groups of the PBEA2ꢀ ligands. The
Cdꢁ ꢁ ꢁCd and Oꢁ ꢁ ꢁO through-space distances across the
˚
dinuclear core measure 3.909 (2) and 2.687 (8) A, respectively.
These rhomboid subunits are noticeably pinched, with Cd—
O—Cd and O—Cd—O angles of 111.0 (2) and 69.00 (17)ꢂ,
respectively. They are linked by the PBEA2ꢀ ligands giving a
˚
Cdꢁ ꢁ ꢁCd distance of 11.2737 (14) A, which corresponds to the
c lattice parameter. The one-dimensional double chains can be
considered as being formed by the edge-sharing of {Cd2O2}
rhomboids with 22-membered {CdOC8O}2 rings. These
[Cd(PBEA)]n double chains are pillared by tethering BTB
ligands, in which the BTB shows a trans–trans–trans confor-
˚
mation, with a Cdꢁ ꢁ ꢁCd separation of 14.6624 (14) A. This
establishes [Cd(PBEA)(BTB)]n two-dimensional coordina-
tion polymer slab patterns that are arranged parallel to the
(010) crystal plane (Fig. 3). If the centroids of the {Cd2O2}
rhomboids are considered as connecting nodes, the slab
Figure 4
A perspective view of the three-dimensional supramolecular structure of
(I), incorporating C—Hꢁ ꢁ ꢁO hydrogen bonds and C—Hꢁ ꢁ ꢁꢀ interactions
(dashed lines).
ꢄ
m174 Wang et al. [Cd(C10H8O4)(C8H12N6)]
Acta Cryst. (2011). C67, m173–m175

metal-organic compounds
and C12—H12ꢁ ꢁ ꢁCg = 156ꢂ. On comparing the structure of
complex (I) with that of the previously reported polymorph of
(I) [(II); Wang et al., 2011], it can be seen that the two
complexes have a similar connectivity within their two-
dimensional layered structures, but that the supramolecular
interactions are different, being more plentiful in (I). Not only
are there more C—Hꢁ ꢁ ꢁO interactions, but also C—Hꢁ ꢁ ꢁꢀ
interactions exist in complex (I). It might be possible that the
differences in conditions during the syntheses, such as pH
value and temperature [433 K for (I) and 413 K for (II)] are
responsible for the differences between the two complexes.
Table 1
Hydrogen-bond geometry (A, ).
ꢂ
˚
D—Hꢁ ꢁ ꢁA
D—H
Hꢁ ꢁ ꢁA
Dꢁ ꢁ ꢁA
D—Hꢁ ꢁ ꢁA
C16—H16Aꢁ ꢁ ꢁO1i
C13—H13Bꢁ ꢁ ꢁO2ii
C7—H7ꢁ ꢁ ꢁO1i
0.97
0.97
0.93
0.97
2.60
2.34
2.55
2.59
3.563 (8)
3.288 (7)
3.380 (7)
3.552 (8)
175
165
149
169
C2—H2Aꢁ ꢁ ꢁO2iii
Symmetry codes: (i) ꢀx þ 2; ꢀy þ 1; ꢀz; (ii) ꢀx þ 2; ꢀy; ꢀz; (iii) ꢀx þ 3; ꢀy; ꢀz.
structure: SHELXTL; molecular graphics: DIAMOND (Branden-
burg, 1999); software used to prepare material for publication:
SHELXTL.
Experimental
A mixture of Cd(NO3)2ꢁ6H2O (34.5 mg, 0.1 mmol), H2PBEA
(19.4 mg, 0.1 mmol), BTB (19.2 mg, 0.1 mmol) and KOH (11.2 mg,
0.2 mmol) in H2O (10 ml) was sealed in a 16 ml Teflon-lined stainless
steel container and heated at 433 K for 72 h. After cooling to room
temperature, colourless block-shaped crystals of (I) were collected by
filtration and washed several times with water and ethanol (yield
41.7%, based on BTB). Elemental analysis for C18H20CdN6O4:
C 43.52, H 4.06, N 16.92%; found: 43.49, H 4.04, N 16.90%.
The authors acknowledge financial support from the
Jiangsu Provincial Key Laboratory of Coastal Wetland Bio-
resources and Environmental Protection (grant No.
JLCBE07014).
Supplementary data for this paper are available from the IUCr electronic
archives (Reference: WQ3002). Services for accessing these data are
described at the back of the journal.
Crystal data
References
[Cd(C10H8O4)(C8H12N6)]
Mr = 496.81
Triclinic, P1
ꢃ = 69.418 (2)ꢂ
3
˚
V = 948.7 (2) A
Z = 2
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˚
a = 9.7900 (13) A
b = 10.1129 (13) A
Mo Kꢁ radiation
ꢄ = 1.19 mmꢀ1
T = 291 K
0.21 ꢃ 0.20 ꢃ 0.19 mm
˚
˚
c = 11.2737 (14) A
ꢁ = 66.198 (2)ꢂ
ꢂ = 87.935 (1)ꢂ
Data collection
Bruker SMART CCD area-detector
diffractometer
Absorption correction: multi-scan
(SADABS; Bruker, 2000)
Tmin = 0.779, Tmax = 0.798
4728 measured reflections
3337 independent reflections
3089 reflections with I > 2ꢅ(I)
Rint = 0.075
Refinement
R[F2 > 2ꢅ(F2)] = 0.039
wR(F2) = 0.122
S = 1.22
262 parameters
H-atom parameteꢀrs3 constrained
˚
Áꢆmax = 1.10 e A
ꢀ3
˚
3265 reflections
Áꢆmin = ꢀ0.81 e A
All C-bound H atoms were placed in calculated positions and
refined using a riding model, with C—H = 0.93 (triazole and
˚
aromatic) or 0.97 A (methylene) and Uiso(H) = 1.2Ueq(C).
Data collection: SMART (Bruker, 2000); cell refinement: SAINT
(Bruker, 2000); data reduction: SAINT; program(s) used to solve
structure: SHELXTL (Sheldrick, 2008); program(s) used to refine
ꢄ
Acta Cryst. (2011). C67, m173–m175
Wang et al.
[Cd(C10H8O4)(C8H12N6)] m175