Hydrogen-bond-based magnetic exchange between μ- diethylnicotinamide(aqua)bis(X-salicylato)copper(II) polymeric chains

Article abstract of DOI:10.1002/zaac.201000301

Polymeric salicylatocopper(II) complexes of unusual composition [Cu(X-sal)₂(μ-denia)(H₂O)]_n [denia = diethylnicotinamide, and X-sal = 5-methylsalicylate (1), 3-methylsalicylate (2), 4-methoxysalicylate (3), 3,5-dichlorosalicylate (4) and 3,5-dibromosalicylate (5)] were synthesized and characterized. Magnetic measurements were performed in the temperature range 1.8-300 K. The structural unit of all complexes consists of a Cu^II atom, which is monodentately coordinated by the pair of X-salicylate anions in trans positions. Water and the diethylnicotinamide ligand occupy the other two basal plane positions of the tetragonal pyramid. The axial positions are occupied by a diethylnicotinamide oxygen atom of neighboring structural units, thus forming a spiral polymeric structure parallel to b axis. Magnetic measurements showed that all complexes 1-5 exhibit a susceptibility maximum at about 6-8 K. The obtained data fit to Bleaney-Bowers equation gave singlet-triplet energy gaps 2J = -8.60 cm^-1 for 1, 2J = -6.57 cm ^-1 for 2, 2J = -8.57 cm^-1 for 3, 2J = -6.82 cm ^-1 for 4, and 2J = -6.45 cm^-1 for 5. The supramolecular structure based on hydrogen bonds [described by supramolecular synthons R ₂²(10) and R₂²(12)] is the pathway for antiferromagnetic interactions of the magnetically coupled pairs of copper atoms of neighboring chains within the 2D supramolecular layers. The results of the magnetic measurements suggest involvement of the COO groups in the magnetic interaction pathway for all five complexes.

Full text of DOI:10.1002/zaac.201000301

ARTICLE
DOI: 10.1002/zaac.201000301
Hydrogen-Bond-Based Magnetic Exchange Between μ-
Diethylnicotinamide(aqua)bis(X-salicylato)copper(II) Polymeric Chains
Maria Korabik,*[a] Zuzana Repická,[b] Ladislav Martiška,[b] Jan Moncol,[b]
Jozef Švorec,[b] Zdeňka Padělková,[c] Tadeusz Lis,[a] Milan Mazúr,[d] and
Dušan Valigura*[b]
In Memory of Professor Tadeusz Głowiak
Keywords: Coordination polymer; Copper; Hydrogen bonds; Magnetic properties; Supramolecular chemistry
Abstract. Polymeric salicylatocopper(II) complexes of unusual com- ments showed that all complexes 1–5 exhibit a susceptibility maximum
position [Cu(X-sal)2(μ-denia)(H2O)]n [denia = diethylnicotinamide,
and X-sal = 5-methylsalicylate (1), 3-methylsalicylate (2), 4-methoxys-
alicylate (3), 3,5-dichlorosalicylate (4) and 3,5-dibromosalicylate (5)]
were synthesized and characterized. Magnetic measurements were per-
formed in the temperature range 1.8–300 K. The structural unit of all
complexes consists of a CuII atom, which is monodentately coordinated
by the pair of X-salicylate anions in trans positions. Water and the
diethylnicotinamide ligand occupy the other two basal plane positions
of the tetragonal pyramid. The axial positions are occupied by a dieth-
ylnicotinamide oxygen atom of neighboring structural units, thus form-
at about 6–8 K. The obtained data fit to Bleaney–Bowers equation
gave singlet-triplet energy gaps 2J = –8.60 cm–1 for 1, 2J = –6.57 cm–1
for 2, 2J = –8.57 cm–1 for 3, 2J = –6.82 cm–1 for 4, and 2J = –
6.45 cm–1 for 5. The supramolecular structure based on hydrogen
bonds [described by supramolecular synthons R2 (10) and R2 (12)] is
the pathway for antiferromagnetic interactions of the magnetically cou-
pled pairs of copper atoms of neighboring chains within the 2D supra-
molecular layers. The results of the magnetic measurements suggest
involvement of the COO groups in the magnetic interaction pathway
2
2
ing a spiral polymeric structure parallel to b axis. Magnetic measure- for all five complexes.
are more stable but have a higher flexibility. They exhibit a
Introduction
fascinating structural diversity and have potential
applications[3] in catalysis,[4] the synthesis of chiral structures,
luminescence,[5] magnetism,[6] nonlinear optics,[7] different
sensor applications, drug design, and porosity exploitation in
separation techniques.[8] The unusual dimeric complex [Cu(5-
MeOsal)2(μ-nia)(H2O)]2 (5-MeOsal = 5-methoxysalicylate an-
ion, nia = nicotinamide)[9] exhibits interesting properties, in-
cluding magnetic interactions mediated by hydrogen bonds. Its
antiferromagnetic properties, which were characterized by the
singlet-triplet energy gap (2J = –6.83 cm–1) were attributed to
interdimer Cu···Cu interactions through carboxylato bridges
extended by O–H···O hydrogen bonds. Recently, a monomeric
nitrobenzoatocopper(II) [Cu(3-O2Nbz)2(nia)(H2O)2] complex
with similar magnetic behavior has been published and its
monomeric molecular structure with supramolecular dimer
formation[10] has proved the previously suggested pathway[9]
of antiferromagnetic interaction and has given the base for un-
derstanding that the spin–spin interaction and consequently the
form of magnetic dimensionality could be different from its
structural dimensionality.
It is no surprise, that hydrogen bonds play an important role
in various fields of science from biology to technical applica-
tions, including coordination chemistry.[1] In the solid state,
hydrogen bonds mainly effect the mutual positions of molecu-
les and allow the formation of different 1D, 2D, or 3D supra-
molecular structures.[2] Complexes linked by hydrogen bonds
* Dr. M. Korabik
E-Mail: jkorab@wchuwr.chem.uni.wroc.pl
* Prof. Dr. D. Valigura
E-Mail: dusan.valigura@stuba.sk
[a] Faculty of Chemistry
University of Wrocław
14 Joliot-Curie St.
50-383 Wrocław, Poland
[b] Department of Inorganic Chemistry
Slovak University of Technology
Radlinskeho 9
812 37 Bratislava, Slovakia
[c] Department of General and Inorganic Chemistry
Faculty of Chemical Technology, University of Pardubice
Nám. Čs. Legií 565
53210 Pardubice, Czech Republic
[d] Department of Physical Chemistry
Slovak University of Technology
Radlinskeho 9
In this report, we describe the synthesis, structure, spectral,
and magnetic properties of five salicylatocopper(II) coordina-
tion polymers: [Cu(5-Mesal)2(μ-denia)(H2O)]n (1), [Cu(3-
Mesal)2(μ-denia)(H2O)]n (2), [Cu(4-MeOsal)2(μ-denia)(H2O)]n
(3), [Cu(3,5-Cl2sal)2(μ-denia)(H2O)]n (4), and [Cu(3,5-
812 37 Bratislava, Slovakia
Supporting information for this article is available on the WWW
under http://dx.doi.org/10.1002/zaac.201000301 or from the
author.
224
© 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
Z. Anorg. Allg. Chem. 2011, 637, 224–231

μ-Diethylnicotinamide(aqua)bis(X-salicylato)copper(II)
Br2sal)2(μ-denia)(H2O)]n (5) (5-Mesal = 5-methylsalicylate; 4-
MeOsal = 4-methoxysalicylate; 3,5-Cl2sal = 3,5-dichlorosali-
cylate, 3,5-Br2sal = 3,5-dibromosalicylate, denia = diethylnico-
tinamide), which have a similar magnetic susceptibility versus
temperature behavior due to their similar structures.
Results and Discussion
Structure of [Cu(X-sal)2(μ-denia)(H2O)]n (1–5)
The structures of compounds 1–5 contain one-dimensional
chains parallel to the b axis. The independent part of each
chain is, in all five cases, formed by a copper(II) atom coordi-
nated in square pyramidal manner. The basal plane of each
CuII coordination polyhedron is formed by two carboxylato
oxygen atoms (O12 and O13) of two salicylato ions in trans
positions (Figure 1).
Figure 2. Perspective view of [Cu(5-Mesal)2(μ-denia)(H2O)]n spiral
chain. The minority parts of disordered groups and the hydrogen atoms
are omitted for clarity.
Supramolecular Structure Relation to Magnetic Properties
The analogy of the hydrogen bridges was the reason for mag-
netic measurements of all complexes 1–5. They exhibited simi-
lar magnetic susceptibility versus temperature functions with a
maximum of the susceptibility in the range 6–8 K (Figure 4
for 1, Figures S4–S7 for 2–5, Supporting Information, and Ta-
ble 2 for the data of all complexes).
[9]
The dimeric complex [Cu(5-MeOsal)2(μ-nia)(H2O)]2 and
especially
the
monomeric
complex
[Cu(3-
O2Nbz)2(nia)(H2O)2][10] as well as all five complexes pre-
sented in this paper exhibit similar magnetic properties, despite
their different structural dimensionalities. The first presented
complex (see above) is dimeric with nicotinamide bridges,[9]
but the second is a monomer without any bridging molecules
except the mentioned hydrogen bonds, so no other pathway
than the system of hydrogen bonds including carboxylate
groups and water molecules coordinated to neighboring cop-
Figure 1. View of [Cu(5-Mesal)2(μ-denia)(H2O)]n (1), with the atom
numbering scheme. Thermal ellipsoids are drawn at the 30 % probabil-
ity level. [Symmetry code: (i) –x–1/2, y–1/2, –z+3/2; (ii) –x–1/2, y+1/
2, –z+3/2].
The pyridine nitrogen atom N1 of denia ligand and the oxy-
gen atom of the water molecule O1W are occupying the re-
maining two basal plane positions. The apical position of each
square pyramid is occupied by the carboxamide oxygen atom
O1 of the adjacent symmetry-related denia molecule, thus
forming a spiral 1D chain (Figure 2). The interatomic distan-
ces and bond angles for all five complexes coordination poly-
hedra are shown in Table 1.
2
per(II) atoms, described by supramolecular synthons R2 (10)
2
and R2 (12) (Scheme 1), is possible.
The strong hydrogen bonding interactions connect the closest
copper(II) ions and are the base of the pathway for the antifer-
romagnetic exchange interactions. To estimate the magnitude
of the coupling, the Bleaney–Bowers[11] susceptibility equa-
tion, derived from spin Hamiltonian H = –2JS1S2, was used for
evaluation:
The neighboring chains are linked by the hydrogen atoms H1W
and/or H2W of coordinated water molecules to the uncoordinated
carboxylate oxygen atoms O13 or O23 of the adjacent polymeric
chain (Figure 3). The hydrogen bonding parameters are given in
2
2
Table 1. Pairs of the supramolecular synthons R2 (10) and R2 (12)
formed between the adjacent copper(II) atoms (Scheme 1) are ob-
served, which are similar to those found in complexes of lower
Taking into consideration the expanded structures of poly-
dimensionalities, [Cu(5-MeOsal)2(μ-nia)(H2O)]2 and/or [Cu(3- meric complexes 1–5, the molecular field model[12] was added
[9]
O2Nbz)2(nia)(H2O)2].[10]
to describe other interactions:
Z. Anorg. Allg. Chem. 2011, 224–231
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225

M. Korabik, D. Valigura et al.
ARTICLE
Table 1. Selected bond lengths and hydrogen bond parameters /Å, ° for 1–5.
1
2
3
4
5
Cu–O12
1.949(2)
1.943(2)
2.007(2)
1.954(2)
2.368(2)
178.0(1)
173.0(1)
90.3(1)
1.935(2)
1.938(2)
2.010(2)
1.955(2)
2.351(2)
176.5(1)
168.9(1)
87.7(1)
1.972(2)
1.943(2)
2.013(2)
1.957(2)
2.386(2)
176.7(1)
172.2(1)
87.8(1)
1.962(2)
1.956(2)
2.006(3)
1.962(2)
2.316(3)
177.3(1)
176.8(1)
91.8(1)
1.958(4)
1.951(4)
2.008(5)
1.957(3)
2.311(4)
177.4(2)
175.6(2)
92.2(2)
Cu–O13
Cu–N1
Cu–O1W
Cu–O1i
O12–Cu–O13
N1–Cu–O1W
O1–Cu–O12
O1–Cu–N1
O1–Cu–O13
O1–Cu–O1W
92.2(1)
94.0(1)
91.6(1)
88.4(1)
89.5(2)
87.7(1)
94.5(1)
88.8(1)
97.1(1)
88.9(1)
96.1(1)
90.6(1)
94.8(1)
90.2(2)
94.7(2)
H1W···O22
1.88
1.81
1.86
1.81
1.81
O1W···O22
2.671(3)
160
2.645(3)
170
2.690(3)
171
2.649(3)
172
2.649(6)
173
O1W–H1W···O22
H2W···O23
1.83
2.643(3)
166
1.87
2.706(3)
172
1.82
2.651(2)
170
1.82
2.651(3)
168
1.83
2.648(5)
166
O1W···O23
O1W–H2W···O23
Symmetry code: (i) –x–1/2, y–1/2, –z+3/2.
Figure 4. Temperature dependence of χm (●) and χmT (○) for 1 (χm
being the molar magnetic susceptibility per copper ion). Solid lines
were obtained for calculated parameters: g = 2.16 0.02, 2J = –
8.60 0.03 cm–1, zJ’ = –0.8 0.1 cm–1, R = 1.6 × 10–4.
Figure 3. Perspective view of hydrogen bonds interactions between
adjacent [Cu(5-Mesal)2(μ-denia)(H2O)]n spiral chains. The minority
parts of disordered groups; ethyl, methyl, and hydroxyl groups; and
the hydrogen atoms are omitted for clarity.
where χm is the molar susceptibility given by the Bleaney–
Bowers equation, zJ' characterizes all other magnetic interac-
tions, and z is the number of the nearest neighbors. Other sym-
bols have their usual meaning: N is the Avogadro number, g is
the spectroscopic splitting factor, β is the Bohr magneton, and
k is the Boltzmann constant. The best fit parameters obtained
are given in Table 2, together with additional structural data.
The resulting singlet-triplet energy gaps 2J of complexes 1–5
are in the range 6–8 cm–1 and are in good agreement with
the temperature of magnetic susceptibility maximum (Table 2).
The temperature Tmax is related to 2J according to |2J| / kTmax
=
1.599,[12] the observed values follow this relation.
The obtained best fit parameters, the singlet-triplet energy
Scheme 1. Supramolecular synthons formed by hydrogen bonds.
gap 2J of 1 and 3 differ from the previously obtained values
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μ-Diethylnicotinamide(aqua)bis(X-salicylato)copper(II)
Table 2. Magnetic measurements and structural data for magneto-structural analysis of 1–5.
1
2
3
4
5
μeff /B.M. (1.8 K)
0.23
0.33
0.13
0.37
0.38
μeff /B.M. (300 K)
1.89
1.87
1.88
1.83
1.78
Tmax /K
2J /cm–1
zJ' /cm–1
g
8.0
6.0
8.0
6.0
6.0
–8.60 0.03
–0.8 0.1
2.16 0.02
1.6 × 10–4
–6.57 0.01
–0.29 0.03
2.18 0.01
1.4 × 10–4
–8.57 0.01
–0.38 0.03
2.17 0.01
1.2 × 10–5
–6.82 0.07
–0.94 0.08
2.15 0.01
8.3 × 10–5
–6.45 0.07
–0.78 0.08
2.13 0.01
8.9 × 10–5
R
τ
0.083
4.622
8.311
8.126
3.219
0.041
2.671
2.643
1.295
1.019
1.064
0.126
4.798
8.386
8.165
3.321
0.066
2.645
2.707
1.350
1.026
0.981
0.074
4.767
8.475
8.155
3.303
0.039
2.689
2.649
1.356
1.010
0.986
0.008
4.946
8.284
8.065
3.190
0.047
2.649
2.651
1.305
0.981
0.982
0.030
4.923
8.249
8.105
3.179
0.057
2.648
2.647
1.297
1.027
0.919
Cu···Cua)
Cu···Cub)
Cu···Cuc)
Basal plane–basal plane
Cu···basal plane
O1W···O22iii
O1W···O23iii
O1W···Cu(COO)2 plane
H1W···Cu(COO)2 plane
H2W···Cu(COO)2 plane
a) Cu···Cu distance of atoms connected by hydrogen bonds. b) Cu···Cu distance of atoms connected by denia bridging molecule. c) Cu···Cu
distance of atoms next to each other within the spiral.
for [Cu(5-MeOsal)2(μ-nia)(H2O)]2 (2J = –6.83 cm–1)[9] or fairly good agreement with the obtained –2J values from mag-
[Cu(3-O2Nbz)2(nia)(H2O)2] (2J = –6.25 cm–1),[10] whereas the
netic measurements (Table 3), thus confirming the idea that
the carboxylato groups are involved in magnetic interaction
2J values of 2, 4, and 5 are similar to those previously ob-
tained. It is easy to relate those two greater –2J values
(8.60 cm–1 for 1 and 8.57 cm–1 for 3, respectively) to the two
shortest (4.62 Å for 1 and 4.77 Å for 3, respectively) Cu···CuA
distances of the copper atoms connected by hydrogen bonds.
It is obvious that the Cu···CuA distance is not the only factor
influencing the interaction. An additional influence could be
documented by the structure of complex 2 in which the
Cu···CuA distance is only slightly greater (4.80 Å) than in com-
plex 3, but the value of the –2J parameter drops significantly
to 6.57 cm–1.
pathway. By changing the φbent angle value the overlap be-
tween the dx –y magnetic orbital of the CuII atoms and the 2p
oxygen orbital of the bridge decreases. The P2–P3 angle values
given in Table 3 show that the COO groups are “bent” sym-
metrically and remain nearly coplanar for complex 3, whereas
in all other complexes additional “twisting” of the COO groups
is present. It should be noted that the studied complexes
slightly differ in mutual orientation of the carboxylato phenyl
rings (Table 3 and Table S1). There is no simple relationship
between magnetic (2J) and structural (e.g. Cu···Cu) parameters
and it is logically supported by the suggestion that the ex-
change pathways between interacting ions are no simple
bridges. Similar conclusions were drawn by Reedijk et al.[14]
They explained magnetic exchange interactions in dinuclear
copper(II) units with the double [O···H(water)] bridge, result-
ing in antiferromagnetic interactions between the CuII ions sep-
arated at a distance of 4.8896 Å, with a singlet-triplet energy
gap of –19.8 cm–1.
2
2
On the other hand, complexes 1 and 3 exhibit an almost
perfect square-pyramidal coordination environment, which is
confirmed by τ parameter[13] values of 0.083 and 0.074, respec-
tively (Table 2), whereas the slightly more distorted square-
pyramidal arrangement of complex 2 (τ = 0.126) could partly
explain differences in the strength of magnetic exchange inter-
actions (2J) within this group of complexes. However, this
conclusion cannot be simply extended to complexes 4 and 5.
Here, the distortion of the square-pyramidal arrangement that
The data discussed above (Table 2 and Table 3) confirm that
the antiferromagnetic interaction of copper atoms with un-
paired spins is realized by specific positioning of coordinated
ligands originated in hydrogen bond formation similar to those
previously reported.[9,10,15] A theoretical investigation of ex-
change coupling through hydrogen bonding[16] has given the
idea, that hydrogen bonds are responsible for fixing molecules,
in our cases macromolecules, in position allowing overlap of
magnetic orbitals. All data [O1W distances from O22, or O23
carboxylato oxygen atoms, the water molecule atoms distances
from Cu(COO)2 plane, etc.] given in Table 2 together with the
above discussed role of COO groups are in good agreement
decreases the overlap of dx –y magnetic orbitals[12] of copper
atoms and consequently decreases the strength of magnetic ex-
change interactions has only little influence. Additionally,
complex 2 differs from the complexes 1 or 3 by the “bent”
position of both COO groups out of the plane defined by the
apical oxygen atom O1, the copper atom and both oxygen at-
oms O12 and O13. These dihedral angles (P1–P2, and/or P1–
P3) are defined to some extent similarly as the φbent angle[13]
for the series of the “paddle-wheel” aromatic copper(II) car-
boxylate functions, where the “abnormally” small value of –
2J = 267 cm–1 (in comparison to values in the range 316–
350 cm–1) was attributed to the average φbent angle of
2
2
11.4(3) °. In our case, the average (P1–Pi)aver values are in with the suggested ideas.[15,16]
Z. Anorg. Allg. Chem. 2011, 224–231
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227

M. Korabik, D. Valigura et al.
ARTICLE
Table 3. Dihedral angles /° of defined planes for 1–5.
P1–P2 anga)
P1–P3 anga)
(P1–Pi)aver
P2–P3 anga)
–2J /cm–1
1
2
3
4
5
5.16
8.49
2.35
4.25
3.62
0.76
13.64
3.29
9.02
8.36
2.96
11.06
2.82
6.64
5.99
5.87
7.43
0.94
4.25
4.74
8.15
6.57
8.57
6.82
6.45
a) P1 = the best plane defined by O12, Cu, O13, and O1 atoms; P2 = the best plane defined by O12, C02 and O22 atoms; P3 = the best plane
defined by O13, C03 and O23 atoms.
The other parameters introduced in magnetic susceptibility
Although most spectra show only small variations with de-
evaluation, the zJ' values, are of small and similar values due creasing temperature, some differences in the behavior of par-
to similar chain structure of polymeric molecules (the same ticular complexes were observed. The most interesting change
bridging denia ligands within the chains, the very similar with lowering of the temperature was found for 4. The liquid
Cu···CuB, or Cu···CuC distances, similar π···π-stacking interac- helium temperature spectrum of 4 showed, in addition to split-
tions of neighboring anion phenyl rings[17] (see Table 2). The ting at about 335 mT, the presence of a clearly resolved half-
denia ligand is no good mediator of magnetic interactions. field transition (159.6 mT), which was not seen in the spec-
Similar conclusions were drawn by magnetic analyses of some trum at room temperature or at 77 K (Figure 5). This is in
chain-like polymeric copper(II) complexes containing 3-pyri- agreement with the triplet spin state with non-negligible zero-
dylmethanol as bridging ligand. They exhibited only very field splitting,[10] below 6 K and confirms a dimeric type of
weak ferromagnetic interactions [18] within the chain (J = antiferromagnetic interactions.
+0.12 cm–1) and the obtained zJ' = –0.07 cm–1 value has been
attributed to interchain interactions.
Spectral Properties of [Cu(X-sal)2(μ-denia)(H2O)]n (1–5)
The EPR powder spectra of the presented complexes at room
temperature are very similar and exhibit mostly the monomeric
pattern of an axial symmetry except the spectrum of 2 (Figure
S11) that shows only a single resonance attributed to isotropic
signal (Table 4). The values of the g tensors gs > g⊥ > ge are
in good agreement with the observed square pyramidal struc-
ture with a dx –y ground state.[19] Unresolved hyperfine split-
ting is observed as a consequence of strong dipolar and ex-
change interactions of the stacked molecules in solid state,
which are in agreement with observed strong hydrogen bonds
in studied complexes.
2
2
Table 4. The g tensor parameters obtained by simulation[20] spectra for
compounds 1–5.
Figure 5. EPR spectrum of 4 at room temperature, 77 K, and 4.2 K
paired with the simulation.
Temperature
g⊥
gs
The spectrum of complex 5 (Figure S13) at 77 K is similar
to the room temperature spectrum. However, broadening of the
perpendicular as well as of the parallel component is observed
at liquid helium temperature. The spectra of 1 (Figure S10)
and 3 (Figure S12) at room temperature and at 77 K are simi-
lar. For all obtained spectra, lowering of the temperature led
to an increase of the signal line width as a consequence of
strong dipolar and exchange interactions.[21]
The IR spectra of all complexes contain the bands corre-
sponding to νas(COO–) and νs(COO–) at about 1618 cm–1 and
1427 cm–1, respectively. The differences between antisymmet-
ric and symmetric stretching (Δν = νas – νs) are greater than
1
2
3
4
77K
2.070
2.070
2.254
2.251
room temp.
77 K
gi = 2.108
gi = 2.108
2.071
room temp.
77 K
2.289
2.291
room temp.
4.2 K
2.069
gx = 2.007 gy = 2.067 gz = 2.225
77 K
2.080
2.078
2.068
2.080
2.079
2.270
room temp.
4.2 K
2.274
2.231
2.240
2.245
5
77 K
room temp.
All EPR spectra in this study were also recorded at a temper- Δν for the ionic form,[22] which is in agreement with the uni-
ature of 77 K, for complexes 3 and 4 spectra were obtained at dentate bonding mode of the carboxylate group proved by X-
4.2 K.
ray analysis (Table 5).
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μ-Diethylnicotinamide(aqua)bis(X-salicylato)copper(II)
Table 5. The infrared spectra for compounds 1–5.
the powdered samples were recorded with
Bruker ER 200-SRC operating at X-band.
a
spectrometer
b)
νas(COO–)
νas(COO–)
Δνa)
Δνion
1
2
3
4
5
1620
1619
1615
1636
1630
1425
1427
1430
1446
1440
195
192
185
190
190
147
147
Magnetization measurements in the temperature range of 1.8–300 K
were carried out on powdered samples of complexes, at the magnetic
field 0.5 T, using a Quantum Design SQUID Magnetometer (type
MPMS-XL5). Corrections for diamagnetism of the constituting atoms
were calculated with Pascal's constants,[12] the value of 60 × 10–6
cm3·mol–1 was used as the temperature-independent paramagnetism of
copper(II) ion. The best exchange parameters were obtained by fitting
with a good agreement factor R defined:
c)
–
c)
–
c)
–
a) Δν = νas(COO–) – νas(COO–). b) Δνion = for ionic form. c) Not
known.
For all complexes broad bands of medium intensity and simi-
lar shape, which were attributed to O–H vibrations, are ob-
served in the region of 3200 cm–1–3000 cm–1.
The solid state electronic spectra of the discussed complexes
exhibit a broad asymmetric ligand field band with a maximum
in the range of 638–632 nm. These d ← d spectra are typical
for the square-pyramidal coordination polyhedra.[23] In addi-
tion, strong intraligand charge-transfer bands (250–300 nm)
and LMCT bands (300–350 nm) were observed.
Preparation of the Complexes
The blue complexes were prepared by similar reactions of aqueous
solutions of copper(II) acetate with N,N-diethylnicotinamide and with
appropriate salicylic acid with some addition of solvent (water or meth-
anol as follows).
[Cu(5-Mesal)2(μ-denia)(H2O)]n
(1)
and
[Cu(3-Mesal)2(μ-
Conclusions
denia)(H2O)]n (2): N,N-diethylnicotinamide (0.17 mL, 1 mmol) was
added to aqueous solution of copper(II) acetate (10 mL, 1 mmol)
whilst stirring. After several minutes solid 5-, or 3-methylsalicylic acid
(0.30 g, 2 mmol) and water (20 mL) were added to the solution. The
reaction mixture was stirred for two days at ambient temperature. The
Five coordination polymers formed by copper(II) salicylate
with diethylnicotinamide were prepared and characterized. The
crystal structures consist of 1D spiral-like polymeric chains
that are held together by strong hydrogen bonds between coor- blue precipitate was filtered off and the mother liquid was left to crys-
tallize at room temperature. The formed crystals were separated and
dried at ambient temperature. The composition of the powder products
were according the elemental analyses and spectral characterizations
the same as the crystal ones (proved by X-ray structure analysis).
dinated water molecules of one chain and carboxylato groups
of the neighboring chain, thus connected into 2D sheets. The
supramolecular structure based on hydrogen O–H···O bonds
2
2
[described by supramolecular synthons R2 (10) and R2 (12)] is
the pathway that causes antiferromagnetic interactions of the
magnetically coupled pairs of copper atoms. The analyzed data
allowed the suggestion that COO groups and coordinated water
molecules are involved in dimeric magnetic interactions of the
polymeric chain compounds. It should be underlined that the
presented complexes are examples in which the structural di-
mensionality is different from the magnetic dimensionality.
The careful analysis of the packing diagram is a very important
step in understanding the magnetic behavior of polynuclear
complexes, and in identifying the possible intermolecular ex-
change pathways.
[Cu(4-MeOsal)2(μ-denia)(H2O)]n (3): The initial procedure was the
same as above with the exception that after several minutes solid 4-
methoxysalicylic acid (0.33 g, 2 mmol) and water (190 mL) were
added to the solution. The product isolation procedure was similar to
the one described above.
[Cu(3,5-Cl2sal)2(μ-denia)(H2O)]n (4) and [Cu(3,5-Br2sal)2(μ-
denia)(H2O)]n (5): The methanol solution (20 mL) of 3,5-dichloromo-
salicylic acid (0.15 g, 0.76 mmol) or 3,5-dibromosalicylic acid
(0.22 g, 0.76 mmol) and N,N-diethylnicotinamide (0.13 mL,
0.77 mmol) was added to an aqueous solution of copper(II) acetate
(20 mL, 0.32 mmol) whilst stirring. The formed precipitates were dis-
solved by addition of methanol (20 mL). The solutions were left for
crystallization at ambient temperature. Formed crystals were separated
and dried at ambient temperature. The compositions of the products
were checked by elemental analyses and were proved by X-ray struc-
ture analyses.
Experimental Section
Physical Measurements
Carbon, hydrogen, and nitrogen analyses were carried out with a
CHNSO FlashEA 1112 Automatic Elemental Analyzer. The copper
content was determined by electrolysis of water solution obtained by
the sample mineralization with a mixture of sulfuric acid and potas-
sium peroxodisulfate.
Analysis [Cu(5-Mesal)2(μ-denia)(H2O)]n (1): C26H30CuN2O8: calcd.
C 55.56; H 5.38; N 4.98; Cu 11.31 %; found: C 55.55; H 5.06; N 4.99;
Cu 11.50 %.
Analysis [Cu(3-Mesal)2(μ-denia)(H2O)]n (2): C26H30CuN2O8: calcd.
C 55.56; H 5.38; N 4.98; Cu 11.31 %; found: C 54.91; H 5.29; N 5.33;
Cu11.72 %.
The electronic spectra (190–1100 nm) of the complexes were meas-
ured in nujol suspension with a SPECORD 200 (Carl Zeiss Jena) spec-
trophotometer at room temperature. The infrared spectra (4000– Analysis [Cu(4-MeOsal)2(μ-denia)(H2O)]n (3): C26H30CuN2O10:
100 cm–1) were recorded with a MAGNA 750 IR (Nicolet) and Nicolet calcd. C 52.57; H 5.09; N 4.72; Cu 11.31 %; found: C 51.44; H 5.09;
5700 FT-IR spectrophotometers at room temperature. EPR spectra of N 5.10; Cu 11.50 %.
Z. Anorg. Allg. Chem. 2011, 224–231
© 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
www.zaac.wiley-vch.de
229

M. Korabik, D. Valigura et al.
ARTICLE
Table 6. Crystallographic data for compounds 1–5.
1
2
3
4
5
Code
ZP158/wal250
ZP91/ZP288
C26H30CuN2O8
562.06
ZP171/wal7/ZV138TM
C26H30CuN2O10
594.06
LM431/tg62
LM413/tg61
Chemical formulaC26H30CuN2O8
C24H22Cl4CuN2O8
671.79
C24H22Br4CuN2O8
849.62
Mr
562.06
Monoclinic, P21/n
Cell setting,
space group
Monoclinic, P21/n
Monoclinic, P21/n
Monoclinic, P21/n
Monoclinic, P21/n
Temperature /K 250(2)a)
150(2)
100(2)
100(2)
100(2)
a /Å
b /Å
c /Å
β /°
V /Å3
Z
16.598(5)
8.126(3)
19.980(6)
100.99(3)
2645.4(15)
4
13.655(3)
8.165(2)
23.753(5)
104.74(3)
2561.2(9)
4
14.297(5)
8.155(3)
22.388(9)
100.37(3)
2567.6(11)
4
15.708(3)
8.065(2)
22.541(3)
105.86(1)
2747.1(9)
4
15.861(1)
8.105(1)
22.955(2)
107.77(1)
2810.0(9)
4
Radiation type Mo-Kα
Mo-Kα
Mo-Kα
Mo-Kα
Mo-Kα
μ /mm–1
0.88
0.91
0.91
1.24
6.52
Crystal size /mm 0.35 × 0.18 × 0.10
0.36 × 0.19 × 0.07
5099, 340
0.30 × 0.20 × 0.09
5227, 368
0.40 × 0.30 × 0.25
4705, 368
0.40 × 0.35 × 0.26
4858, 368
No. of reflec-
tions, No of pa-
rameters
5356, 327
Rint
0.061
0.056
0.039, 0.078, 1.04
0.061
0.044, 0.080, 1.065
0.066
0.050, 0.124, 1.10
0.120
0.055, 0.107, 1.11
R [F2 > 2σ(F2)], 0.050, 0.102, 1.06
wR (F2), S
Δρmax, Δρmin
e·Å–3
/
0.27, –0.27
0.27, –0.31
0.37, –0.30
0.52, –0.60
0.64, –0.70
a) X-ray data of complex 1 were firstly obtained at 100 K but they were not suitable for solving structure.[30]
Analysis [Cu(3,5-Cl2sal)2(μ-denia)(H2O)]n (4): C26H26Cl4CuN2O8: The both hydroxyl group of both of the 3,5-dichlorosalicylate ligands
calcd. C 42.91; H 3.30; N 4.17; Cu 9.46 %; found: C 42.45; H 3.16; of 4 are disordered and the refined site-occupancy factors of the two
N 3.99; Cu 10.03 %.
disordered parts are 0.70 and 0.10; 0.91, and 0.09. One of the ethyl
groups of N,N-diethylnicotinamide ligand of 4 is disordered and the
refined site-occupancy factors of the two disordered parts are 0.43 and
0.57, respectively. Similarly, both hydroxyl groups of the 3,5-dibromo-
salicylate ligands of 5 are disordered and the refined site-occupancy
factors of the two disordered parts are 0.73 and 0.27; 0.88, and 0.12,
respectively. One of the ethyl groups of N,N-diethylnicotinamide li-
gand of 5 is disordered and the refined site-occupancy factors of the
two disordered parts are 0.42 and 0.58, respectively. Thermal ellipsoids
of disordered nitro groups were constrained by EADP instructions. The
C–C and C···C distances were restrained by SADI instructions. Ther-
mal ellipsoids of disordered nitro-groups were constrained by EADP
instructions.
Analysis [Cu(3,5-Br2sal)2(μ-denia)(H2O)]n (5): C26H26Br4CuN2O8:
calcd. C 33.93; H 2.61; N 3.29; Cu 7.48 %; found: C 34.15; H 2.06;
N 3.49; Cu 7.50 %.
X-ray Crystallography
The crystal data and details of data collections for all structures are
given in Table 6. Intensity data were collected with a diffractometer
Kuma KM-4 CCD[24] or a Bruker-Nonius KappaCCD[25] with graphite
monochromated Mo-Kα radiation. The diffraction intensities were cor-
rected for Lorentz and polarization effects. Absorption corrections
were applied using the programs CrysAlis-RED[24] or SADABS.[26]
The structures were solved by direct methods using the programs
SHELXS-97[27] or SIR-97[28] and refined by the full-matrix least-
squares method on all F2 data using the program SHELXL-97.[27] Geo-
metrical analyses were performed using SHELXL-97 program. The
structures were drawn by XP in SHELXTL[27] and MERCURY[29] pro-
grams.
Crystallographic data for the structural analysis have been deposited
with the Cambridge Crystallographic Data Centre CCDC nos. CCDC-
774006 (1), -774007 (2), -774008 (3), -774009 (4), and CCDC-774010
(5). Further details of the crystal structures investigations are available
free of charge via www.ccdc.cam.ac.uk/conts/retrieving.html (or from
the CCDC, 12 Union Road, Cambridge CB2 1EZ, UK; Fax: +44-1223-
336033; E-Mail: deposit@ccdc.cam.ac.uk).
The one of the 5-methylsalicylate ligands as well as the one of the
methyl group of N,N-diethylnicotinamide ligands of complex 1 are
disordered and the refined site-occupancy factors of the two disordered
parts are 0.42 and 0.58, respectively, for both disordered groups. The
C–C, C–O, C···C, and C···O distances were restrained by SADI instruc-
tions of SHELXL-97. Thermal ellipsoids of disordered nitro groups
were constrained by EADP instructions of SHELXL-97.
Supporting Information (see footnote on the first page of this article):
The supplementary Figures S1–S13 and Table S1.
Acknowledgement
The hydroxyl group of one of the 4-methoxysalicylate ligands of 3 is This work was supported by the Slovak Research and Development
disordered and the refined site-occupancy factors of the two disordered Agency under the contract No. VVCE-0004-07. We thank Ministry of
parts are 0.48 and 0.52, respectively. Thermal ellipsoids of disordered Education of the Czech Republic (Project VZ0021627501), and Uni-
nitro-groups have been constrained by EADP instructions.
versity of Wrocław for financial support.
230 www.zaac.wiley-vch.de
© 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
Z. Anorg. Allg. Chem. 2011, 224–231

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Received: July 30, 2010
Published Online: December 29, 2010
Z. Anorg. Allg. Chem. 2011, 224–231
© 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
www.zaac.wiley-vch.de
231