Catena-Poly[[[pyridine-copper(II)]bis-[μ3-4-(2-oxidobenzyl- ideneamino)-benzoato]] dimethyl-formamide disolvate], a polymer composed of dimeric dicopper building units

Article abstract of DOI:10.1107/S010827010703781X

The title compound, {[Cu(C14H9NO3)(C5H5N)]·C3H7NO} n or {[Cu2 L 2(py)2]·2DMF} n [py is pyridine, L is 4-(salicylidene-amino)benzoate and DMF is dimethyl-formamide], is composed of dimeric dicopper [CuL(py)]2 building units, which are inter-linked into a o

Full text of DOI:10.1107/S010827010703781X

metal-organic compounds
Acta Crystallographica Section C
Crystal Structure
Communications
copper complexes with these ligands exhibit antiferromagnetic
exchange (Bai et al., 2006; Shyu et al., 1996). Considering that
such dimers would exhibit unusual magnetic behavior when
introduced into metal±organic frameworks as `magnetic brick'
building blocks, we focused our preparative efforts on
exploiting these `magnetic bricks' to create new architectures.
In this work, the bridging ligand 4-(salicylideneamino)benzoic
acid (H2L), which was derived from the condensation of
salicylaldehyde and 4-aminobenzoic acid, was exploited to
bridge the `bricks' of a dimeric dicopper complex into poly-
meric {[CuL(py)]2Á2DMF}n (py is pyridine and DMF is
dimethylformamide), (I), through a self-assembly process.
ISSN 0108-2701
catena-Poly[[[pyridinecopper(II)]-
bis[l3-4-(2-oxidobenzylideneamino)-
benzoato]] dimethylformamide
disolvate], a polymer composed
of dimeric dicopper building units
Qing-Ling Ni,a Fa-Si Li,a Xiu-Jian Wang,a* Xian-Su Bia and
Sen Liaob
aSchool of Chemistry and Chemical Engineering, Guangxi Normal University, Guilin
541004, People's Republic of China, and bSchool of Chemistry and Chemical
Engineering, Guangxi University, Nanling 530004, People's Republic of China
Correspondence e-mail: wang1_xj@yahoo.com.cn
Received 11 June 2007
Accepted 1 August 2007
Online 17 August 2007
The title compound, {[Cu(C14H9NO3)(C5H5N)]ÁC3H7NO}n or
{[Cu2L2(py)2]Á2DMF}n [py is pyridine, L is 4-(salicylidene-
amino)benzoate and DMF is dimethylformamide], is
composed of dimeric dicopper [CuL(py)]2 building units,
which are interlinked into a one-dimensional chain through
the formation of CuÐOCOO bonds. The dimeric unit is
centrosymmetric, containing two CuII atoms linked by
bridging phenolate O atoms into a Cu2O2 plane with a
Single-crystal structural analysis reveals that the title
compound, which crystallized in the triclinic P1 group, is
composed of dimeric [CuL(py)]2 building units, which are
interlinked through the formation of CuÐOCOO bonds into a
one-dimensional polymer along the crystallographic c axis.
The asymmetric unit of (I) consists of half of the dimer along
with one DMF solvent molecule (Fig. 1). The dimeric unit is
Ê
chelating CuÐO bond length of 1.927 (2) A and a bridging
Ê
CuÐO bond length of 2.440 (2) A. Interchain CÐHÁ Á ÁO and
ꢀ±ꢀ stacking interactions are responsible for an extensive
three-dimensional structure in which the resulting channels
are ®lled by DMF solvent molecules.
Comment
The design and construction of metal±organic frameworks is
of great interest owing to their potential as new functional
materials, as well as their fascinating variety of topologies
(Kitagawa et al., 2004; Steel, 2005; Takaoka et al., 2005). By
rational choice of organic ligand and transition metal ion, one
aims to modify the structure and the physical properties of
complex architectures. Recently, use of a second building
block has been demonstrated to be fruitful in constructing and
analyzing structures of complex architecture (Kim et al., 2001).
Schiff bases are excellent as ligands and are employed for
preparing complexes with special functions, such as biological
activity, catalysis or magnetism. A salen-type Schiff base
[H2salen is bis(salicylidene)ethylenediamine] is one of the
most appealing candidates for the formation of dimeric
dinuclear complexes through the bridging phenolate O atoms
(Bai et al., 2006; Iskander et al., 2000). Numerous dimeric
Figure 1
A displacement ellipsoid representation (at the 30% probability level) of
the coordination environment of the CuII atom in the title compound.
Unlabeled atoms are related by an inversion center to the labeled atoms.
[Symmetry codes: (i) x + 1, y, z + 1; (ii) x + 1, y, z.]
m416 # 2007 International Union of Crystallography
DOI: 10.1107/S010827010703781X
Acta Cryst. (2007). C63, m416±m418

metal-organic compounds
centrosymmetric, with the Cu2O2 plane bridged by two
Ê
hindrance of pyridyl rings and benzene rings around the
Cu2O2 plane. The pyridyl ring is almost perpendicular to the
Cu2O2 plane, with a dihedral angle of 91.6ꢀ. On further
comparison with the most closely related phenolate-O-brid-
ging dinuclear copper compounds, it was found that the
bridging CuÐO bond lengths are similar to the chelating
bonds if the chelating and bridged phenolate O atoms are in
the same equatorial plane (Paschke et al., 2003). The long
bridging bond length and the long CuÁ Á ÁCu separation in the
Cu2O2 plane reveal that the dimerization of the title
compound is a little loose. In the polymer, there is one subunit
of the binuclear Cu2L2 macrocycle, which is stabilized by ꢀ±ꢀ
stacking interactions between the rings of the benzoate
phenolate O atoms. The CuÁ Á ÁCu separation is 3.300 (5) A and
the Cu1ÐO1ÐCu1i angle is 97.50 (9)ꢀ in the Cu2O2 plane
[symmetry code: (i) x + 1, y, z + 1]. Such dimerization via
the bridging phenolate O atoms has been noted previously in
the generation of simple binuclear complexes.
In the dimeric unit, each copper(II) center is in a square-
pyramidal geometric environment, with the basal plane
consisting of a chelating phenolate O atom and an imine N
atom from one ligand, a carboxylate O atom from a neigh-
boring dimer, and a pyridyl N atom, and the apical site
occupied by a bridging phenolate O atom from another ligand
in the dimer. The coordination polyhedron around each
copper center is best described as (4+1) distorted square
pyramidal, with the value of the tetragonality parameter ꢁ
equal to 0.158 [ꢁ = (ꢂ ꢃ)/60, where ꢃ and ꢂ are the N1Ð
Cu1ÐN2 and O1ÐCu1ÐO3ii angles, respectively (Addison et
al., 1984); symmetry code as in Table 1]. The CuÐO bond
Ê
groups, with a centroid±centroid distance of 3.677 A, an
Ê
interplanar distance of 3.154 A and a shift between the
Ê
centroids of 1.890 A. The CuÁ Á ÁCu distance in this macrocycle
Ê
is 8.953 A, a value intermediate between those observed for
other Cu2II complexes containing similar aromatic spacers
(Paital et al., 2007). Adjacent macrocycles are linked by two
bridging phenolate O atoms. Therefore, this polymer can also
be described as being composed of binuclear macrocycles
interlinked through the formation of bridging CuÐOphenol
bonds (Fig. 2), based on the long bridging CuÐOphenol
distances.
Ê
lengths (average 1.928 A) are shorter than the CuÐN bonds
Ê
(average 2.029 A) in the basal plane. The chelating CuÐO
Ê
length of 1.927 (2) A is shorter than the bridging length of
Ê
2.440 (2) A, as is the situation in [Cu(LBPh3)]2 [LBPh3 is
N-(salicylidene)-N0-(1-triphenylborylimidazol-2-ylmethylene)-
1,3-propanediamine; Shyu et al., 1996]. However, the CuÁ Á ÁCu
separation in the Cu2O2 plane is longer than that in
It is worth noting that unusual supramolecular interactions
in the solid state, including CÐHÁ Á ÁO hydrogen bonds and
ꢀ±ꢀ stacking, generate a unique supramolecular architecture.
Ê
[Cu(LBPh3)]2 [3.085 (4) A], possibly because of the steric
Interchain C3ÐH3Á Á ÁO2iii contacts [C3Á Á ÁO2iii = 3.300 (5) A,
Ê
iii
H3Á Á ÁO2iii = 2.45 A and C3ÐH3Á Á ÁO2 = 152ꢀ; symmetry
Ê
code: (iii) x, y 1, z + 1], together with ꢀ±ꢀ stacking inter-
actions between pyridyl rings (the centroid±centroid distance
Ê
is 3.718 A, the interplanar distance is 2.738 A and the shift
Ê
Ê
between the centroids is 2.517 A), drive polymers to arrange
along the crystallographic b axis, while the polymers also
extend along the a axis through interchain ꢀ±ꢀ stacking
interactions between aromatic rings of salicylaldimine groups
Figure 2
A view of the chain along the crystallographic c axis.
Ê
(the centroid±centroid distance is 3.638 A, the interplanar
Ê
distance is 2.742 A and the shift between the centroids is
Ê
2.391 A) (Muller-Dethlefs & Hobza, 2000). These weak
È
interactions are responsible for an extensive three-dimen-
sional structure in which the resulting channels are ®lled by
DMF solvent molecules (Fig. 3).
Experimental
For the synthesis of H2L, a solution of salicylaldehyde (0.9780 g,
8 mmol) in CH3OH (10 ml) was added to a solution of 4-amino-
benzoic acid (1.096 g, 8 mmol) in CH3OH (50 ml) with stirring. A
large amount of yellow precipitate was formed immediately. The
slurry mixture was stirred vigorously for a further 4 h and ®ltered.
The yellow powder product was recrystallized from CH3CH2OH
(80 ml) for puri®cation. For the synthesis of the title complex, a
solution of Cu(ClO4)2Á6H2O (0.0373 g, 0.1 mmol) in DMF (5 ml) was
added to a solution of H2L (0.0482 g, 0.2 mmol) and Et3N (0.0552 ml,
0.4 mmol) in DMF (5 ml) with stirring. The resulting precipitate was
®ltered off and dissolved in pyridine (2 ml). Ethyl ether was diffused
into the pyridine solution. Two weeks later, crystals were selected for
X-ray diffraction.
Figure 3
The packing of the title compound, projected along the a axis. The three-
dimensional network with channels is obtained by interchain CÐHÁ Á ÁO
interactions and ꢀ±ꢀ stacking. DMF solvent molecules are encapsulated
in the channels.
ꢁ
Acta Cryst. (2007). C63, m416±m418
Ni et al.
[Cu(C14H9NO3)(C5H5N)]ÁC3H7NO m417

metal-organic compounds
Crystal data
structure: SHELXS97 (Sheldrick, 1997a); program(s) used to re®ne
structure: SHELXL97 (Sheldrick, 1997a); molecular graphics:
SHELXTL (Sheldrick, 1997b); software used to prepare material for
publication: SHELXTL.
[Cu(C14H9NO3)(C5H5N)]ÁC3H7NO
ꢄ = 80.138 (2)ꢀ
3
Ê
Mr = 454.96
Triclinic, P1
V = 1051.7 (3) A
Z = 2
Ê
a = 8.9547 (13) A
b = 10.6215 (15) A
Ê
c = 11.3899 (16) A
ꢃ = 80.393 (5)ꢀ
ꢂ = 86.408 (3)ꢀ
Mo Kꢃ radiation
1
Ê
ꢅ = 1.07 mm
T = 298 (2) K
This work was sponsored by the National Natural Science
Foundation of China (grant No. 20463001), the NSF of
Guangxi Province (grant No. 0447031) and the State Key
Laboratory of Coordination Chemistry, Nanjing University,
China.
0.23 Â 0.20 Â 0.16 mm
Data collection
Bruker SMART CCD area-detector
diffractometer
Absorption correction: multi-scan
(SADABS; Bruker, 1998)
Tmin = 0.752, Tmax = 0.842
7282 measured re¯ections
4757 independent re¯ections
3900 re¯ections with I > 2ꢆ(I)
Rint = 0.093
Supplementary data for this paper are available from the IUCr electronic
archives (Reference: AV3097). Services for accessing these data are
described at the back of the journal.
Re®nement
R[F2 > 2ꢆ(F2)] = 0.059
wR(F2) = 0.184
S = 1.09
246 parameters
H-atom parameters constrained
References
3
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Ê
Áꢇmax = 1.07 e A
3
Ê
0.64 e A
4757 re¯ections
Áꢇmin
=
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ꢀ
Ê
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Cu1ÐO1i
Cu1ÐO3ii
1.927 (2)
2.440 (2)
1.930 (2)
Cu1ÐN2
Cu1ÐN1
2.020 (3)
2.038 (3)
O1ÐCu1ÐO3ii
O1ÐCu1ÐN2
O3iiÐCu1ÐN2
O1ÐCu1ÐN1
O3iiÐCu1ÐN1
N2ÐCu1ÐN1
176.68 (9)
90.46 (10)
91.26 (10)
89.10 (11)
89.86 (11)
167.16 (12)
O1ÐCu1ÐO1i
O3iiÐCu1ÐO1i
N2ÐCu1ÐO1i
N1ÐCu1ÐO1i
Cu1ÐO1ÐCu1i
82.50 (9)
94.38 (10)
100.60 (10)
92.06 (10)
97.50 (9)
È
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È
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All H atoms were positioned geometrically, with CÐH distances of
Ê
0.93 or 0.96 A, and re®ned using a riding model.
Data collection: SMART (Bruker, 1998); cell re®nement: SAINT
(Bruker, 1998); data reduction: SAINT; program(s) used to solve
ꢁ
m418 Ni et al. [Cu(C14H9NO3)(C5H5N)]ÁC3H7NO
Acta Cryst. (2007). C63, m416±m418