Synthesis and crystal structure of a new Cd(II) coordination polymer based on a 1,10-phenanthroline derivative

Article abstract of DOI:10.1515/znb-2011-0515

The new coordination polymer [Cd(oct)(L)] (H₂oct = octanedioic acid and L = 2-(4-fluorophenyl)-1H-imidazo-[4,5-f][1,10]phenanthroline) has been synthesized under hydrothermal condition and characterized by elemental analysis, IR spectroscopy and single-crystal X-ray diffraction. Crystal data: C₂₇H₂₃CdFN₄O₄, monoclinic, space group C2/c, a = 21.391(4), b = 18.180(4), c = 14.031(3) A, β = 116.50(3), V = 4883(2) A³, Z =8. The flexible oct dianions bridge the Cd(II) cations to yield a double-chain structure. The L ligands are attached on both sides of the chains, and their π-π interactions between neighboring chains result in two-dimensional supramolecular layers.

Full text of DOI:10.1515/znb-2011-0515

538
Note
˚
Table 1. Selected bond lengths (A) and angles (deg) for 1
Synthesis and Crystal Structure of
a New Cd(II) Coordination Polymer
Based on a 1,10-Phenanthroline
Derivative
with estimated standard deviations in parenthesesa.
Cd(1)–O(1)
Cd(1)–O(3)i
Cd(1)–O(3)ii
Cd(1)–N(2)
2.3784(19)
2.613(2)
2.3335(19)
2.3211(19)
Cd(1)–O(2)
Cd(1)–O(4)i
Cd(1)–N(1)
2.4314(17)
2.2617(19)
2.4200(18)
O4i–Cd1–N2
O4i–Cd1–O3ii
N2–Cd1–O1
O4i–Cd1–N1
O3ii–Cd1–N1
O4i–Cd1–O2
O3ii–Cd1–O2
N1–Cd1–O2
N2–Cd1–O3i
O1–Cd1–O3i
170.44(8)
89.89(8)
84.90(7)
N2–Cd1–O3ii
O4i–Cd1–O1
O3ii–Cd1–O1
N2–Cd1–N1
O1–Cd1–N1
N2–Cd1–O2
O1–Cd1–O2
O4i–Cd1–O3i
O3ii–Cd1–O3i
N1–Cd1–O3i
81.49(7)
92.37(7)
98.52(7)
70.23(7)
133.78(6)
83.70(7)
54.14(6)
52.91(6)
77.09(8)
76.86(6)
Zhan-Lin Xu, Shuai Ma, Yu He, and Zhi-Guo Kong
Department of Chemistry, Jilin Normal University,
Siping 136000, China
117.58(8)
114.71(6)
102.13(7)
150.01(7)
84.09(6)
128.01(6)
144.57(6)
131.85(6)
Reprint requests to Prof. Zhi-Guo Kong.
E-mail: kongzhiguo1977@yahoo.com.cn
Z. Naturforsch. 2011, 66b, 538 – 540;
received February 16, 2011
O2–Cd1–O3i
The new coordination polymer [Cd(oct)(L)] (H2oct =
octanedioic acid and L = 2-(4-fluorophenyl)-1H-imidazo-
[4,5-f][1,10]phenanthroline) has been synthesized under hy-
drothermal condition and characterized by elemental anal-
ysis, IR spectroscopy and single-crystal X-ray diffraction.
Crystal data: C27H23CdFN4O4, monoclinic, space group
a
Symmetry transformations used to generate equivalent atoms:
−x+1, −y+1, −z+1; ii x, −y+1, z+1/2.
i
form π-π interactions [6]. On this basis, a number of
coordination polymers have been prepared from one-
dimensional covalently bonded chains or layers, yield-
ing extended two- or three-dimensional supramolec-
ular structures through these interactions [7 – 9].
However, specially designed derivatives such as 2-(4-
fluorophenyl)-1H-imidazo[4,5-f][1,10]phenanthroline
(L), which are good candidates for the construction of
supramolecular architectures, have not been well stud-
ied in coordination chemistry [1]. Here, octanedioic
acid (H2oct) and L were selected as an organic linker
and an N-donor chelating ligand, respectively, to yield
a new coordination polymer, [Cd(oct)(L)] (1).
˚
C2/c, a = 21.391(4), b = 18.180(4), c = 14.031(3) A, β =
3
˚
116.50(3), V = 4883(2) A , Z = 8. The flexible oct dianions
bridge the Cd(II) cations to yield a double-chain structure.
The L ligands are attached on both sides of the chains, and
their π-π interactions between neighboring chains result in
two-dimensional supramolecular layers.
Key words: Coordination Polymer, Crystal Structure,
Octanedioic Acid, 2-(4-Fluorophenyl)-1H-
imidazo[4,5-f][1,10]phenanthroline
Results and Discussion
Introduction
Structure description
The rational design and synthesis of new extended
supramolecular networks that can provide new shapes,
Single-crystal X-ray structural analysis has revealed
sizes and chemical environments have attracted con- that the compound has a two-dimensional supramolec-
siderable attention in supramolecular chemistry [1 – 3]. ular layer structure. Selected bond lengths and an-
Usually, these complexes can be specially designed by gles for 1 are given in Table 1. As illustrated in
the careful selection of metal cations with preferred Fig. 1, the central Cd atom is coordinated by two
coordination geometries, the structure of the connect- nitrogen atoms from one L ligand, and five carb-
ing ligands, and the reaction conditions [4]. Generally, oxylate oxygen atoms from three different oct lig-
two different types of interactions, such as covalent or ands in a distorted pentagonal bipyramidal geom-
ionic bonds and non-convalent intermolecular forces, etry. The Cd–O distances range from 2.2617(19)
˚
can be used to construct a variety of supramolecular to 2.613(2) A. The Cd(1)–N(1) and Cd(1)–N(2) dis-
˚
architectures [5]. In this regard, simple 1,10-phen- tances are 2.4200(18) and 2.3211(19) A, respectively
anthroline ligands have been widely used to construct (Table 1), which are near to the data reported for
such architectures because of their excellent coordinat- [Cd2(Dpq)2(BPDC)2] ·1.5 H2O (Dpq is dipyrido[3,2-
ing ability and large conjugated system that can easily d:2,30-f]quinoxaline, and BPDC is biphenyl-4,4ꢀ-di-
c
0932–0776 / 11 / 0500–0538 $ 06.00 ꢀ 2011 Verlag der Zeitschrift fu¨r Naturforschung, Tu¨bingen · http://znaturforsch.com
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Note
539
Fig. 1 (color online). The coor-
dination environment of the Cd
atom in [Cd(oct)(L)].
Fig. 2 (color online). View of
the double-chain structure of
[Cd(oct)(L)].
Table 2. Crystal structure data for 1.
Formula
Mr
C27H23CdFN4O4
598.89
0.21×0.18×0.16
monoclinic
C2/c
21.391(4)
18.180(4)
14.031(3)
Crystal size, mm3
Crystal system
Space group
˚
a, A
˚
b, A
˚
c, A
β, deg
116.50(3)
4883(2)
3
˚
V, A
Z
8
1.63
0.9
2416
Dcalcd, g cm−3
µ(MoKα ), mm−1
F(000), e
hkl range
Fig. 3 (color online). A two-dimensional supramolecular
layer of [Cd(oct)(L)] constructed by π-π interactions.
−27 ≤ h ≤ 25; −23 ≤ k ≤ 23;
−18 ≤ l ≤ 18
3.0 – 27.5
carboxylate) [11]. It is interesting to note that the two
carboxylates of the oct anions show different coordi-
nation modes (Fig. 2): one bridges two Cd(II) atoms,
while the other connects one Cd(II) atom in a chelat-
ing mode. In this way, each oct dianion bridges two
Cd(II) cations to form a chain structure. In the oct
unit the C(22)–C(26) chain is fully extended (all-trans-
conformation) except for a kink at C(21). It is fur-
ther noteworthy that the L ligands are attached in pairs
on both sides of the chains. There is strong π-π in-
teraction between the ligands of pairs of the chain
θ range, deg
Refl. collect. / unique / Rint
Data / ref. parameters
R1 / wR2 [I ≥ 2σ(I)]
R1 / wR2 (all data)
GoF (F2)
22841 / 5582 / 0.035
5082 / 334
0.0292 / 0.0636
0.0430 / 0.0677
1.039
−3
˚
∆ρmax/min, e A
0.380 / −0.380
˚
(centroid-to-centroid distance 3.41 A, face-to-face dis-
˚
tance 3.35 A). The ligands L are arranged in a paral-
lel fashion, leading to a structure suitable to form π-π
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540
Note
interactions between these pairs (Fig. 3). The lateral pH value of the system was adjusted to between 5 and 6.
The resulting solution was stirred for about 1 h at r. t., sealed
in a 23-mL Teflon-lined stainless-steel autoclave and heated
at 465 K for 7 d under autogeneous pressure. Afterwards, the
reaction system was slowly cooled to r. t. Pale-yellow block-
shaped crystals of 1 suitable for single-crystal X-ray diffrac-
tion analysis were collected by filtration, washed several
times with distilled water and dried in air at ambient tempera-
ture. Yield: 33 % based on Cd. – Anal. for C27H23CdFN4O4:
calcd. C 54.15, H 3.87, N 9.35; found C 54.34, H 3.49,
N 9.22. – IR (KBr, cm−1): ν = 1709w, 1610m, 1584s, 1457s,
1420w, 1455w, 1362w, 1343s, 847w, 723w, 650w.
ligands L from adjacent chains form strong π-π inter-
˚
actions (centroid-to-centroid distance 3.39 A, face-to-
˚
face distance 3.34 A) resulting in an interesting two-
dimensional supramolecular layer (Fig. 3). Obviously,
the π-π stacking interactions play an important role in
the formation and stabilization of the supramolecular
structure. In addition, N–H···O hydrogen bonding in-
teractions further stabilize the structure of 1.
As far as we know several Cd(II) complexes with
phen-like chelating ligands have been reported so far,
however, no Cd(II) coordination polymer containing
a chelating ligand L and a flexible dicarboxylate has
been observed [6 – 11]. It is noteworthy that the struc-
ture of 1 is entirely different from that of the related
compound [Cd2(Dpq)2(BPDC)2] ·1.5 H2O, in which
the BPDC ligands link the Cd(II) centers to give an in-
teresting six-connected twofold interpenetrated frame-
work [11].
X-Ray structure determination
Single-crystal X-ray diffraction data for complex 1 were
recorded at a temperature of 293(2) K on a Rigaku RAXIS-
RAPID diffractometer, using the ω scan technique with
˚
MoKα (λ = 0.71073 A) radiation. The structure was solved
by Direct Methods with SHELXS-97 [12] and refined
by full-matrix least-squares techniques using the program
SHELXL-97 [13]. Non-hydrogen atoms were refined with
anisotropic displacement parameters, and hydrogen atoms of
the ligands were refined as rigid groups. Numbers pertinent
to data collection and refinement are listed in Table 2.
CCDC 813008 contains the supplementary crystallo-
graphic data for this paper. These data can be obtained free
of charge from The Cambridge Crystallographic Data Centre
via www.ccdc.cam.ac.uk/data request/cif.
Experimental Section
General
All the materials were of analytical reagent grade and used
as received without further purification. The IR spectrum was
obtained on a Perkin-Elmer 2400LSII spectrometer. Elemen-
tal analysis was carried out with a Perkin-Elmer 240C ana-
lyzer.
Acknowledgement
Synthesis of compound 1
The authors thank the Key Laboratory of Preparation and
Applications of Environmentally Friendly Materials and the
Institute Foundation of Siping City (No. 2009011) for sup-
porting this work.
A mixture of Cd(NO3)2 · 2.5 H2O (0.5 mmol), H2oct
(0.5 mmol) and L (0.5 mmol) was dissolved in 12 mL dis-
tilled water, followed by addition of triethylamine until the
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