New heterometallic coordination polymers constructed from 3d-3d′ binuclear nodes

Article abstract of DOI:10.1039/c0nj00238k

Heterobinuclear [Cu^IIMn^II] and [Cu ^IICo^II] cationic complexes can efficiently act as nodes for designing coordination polymers. The crystal structures of two binuclear precursors, [LCuCo(NO₃)₂] (1) and [LCuMn(NO ₃)₂] (2), have been solved (L^2- is the dianion of the Schiff base resulting from the 2:1 condensation of 3- methoxysalicyladehyde with 1,3-propanediamine). The nitrato ligands, coordinated to Co^II and, respectively, the Mn^II ions from the precursors, are easily replaced by exo-dentate ligands, resulting in 1-D coordination polymers: ¹_∞[L(H₂O)CuCo(oxy- bbz)]·CH₃CN·C₂H₅OH (3), ¹_∞[L(H₂O)CuCo(2,5-dhtp)]·CH ₃CN (5) and _∞[L(H₂O)CuMn(ox)] ·3H₂O (6) (oxy-bbz^2- = the dianion of 4,4′-oxy-bis(benzoic) acid; 2,5-dhtp^2- = the dianion of 2,5-dihydroxy-terephthalic acid; ox^2- = the dianion of the oxalic acid). In the case of the [CuMn] node, the interaction with oxy-bbz^2- affords a binuclear complex, [LCuMn(oxy-bbz)(H₂O)₂] (4).

Full text of DOI:10.1039/c0nj00238k

View Article Online / Journal Homepage / Table of Contents for this issue
PAPER
www.rsc.org/njc | New Journal of Chemistry
New heterometallic coordination polymers constructed from 3d–3d0
binuclear nodeswzy
Diana G. Branzea,a Augustin M. Madalan,a Samuele Ciattini,b Narcis Avarvari,c
Andrea Caneschib and Marius Andruh*a
Received (in Montpellier, France) 31st March 2010, Accepted 7th June 2010
DOI: 10.1039/c0nj00238k
Heterobinuclear [CuIIMnII] and [CuIICoII] cationic complexes can efficiently act as nodes for
designing coordination polymers. The crystal structures of two binuclear precursors,
[LCuCo(NO3)2] (1) and [LCuMn(NO3)2] (2), have been solved (L2ꢀ is the dianion of the
Schiff base resulting from the 2 : 1 condensation of 3-methoxysalicyladehyde with
1,3-propanediamine). The nitrato ligands, coordinated to CoII and, respectively, the MnII ions
from the precursors, are easily replaced by exo-dentate ligands, resulting in 1-D coordination
1
1
polymers: N[L(H2O)CuCo(oxy-bbz)]ꢁCH3CNꢁC2H5OH (3), N[L(H2O)CuCo(2,5-dhtp)]ꢁCH3CN
(5) and N[L(H2O)CuMn(ox)]ꢁ3H2O (6) (oxy-bbz2ꢀ = the dianion of 4,40-oxy-bis(benzoic) acid;
2,5-dhtp2ꢀ = the dianion of 2,5-dihydroxy-terephthalic acid; ox2ꢀ = the dianion of the oxalic
acid). In the case of the [CuMn] node, the interaction with oxy-bbz2ꢀ affords a binuclear
complex, [LCuMn(oxy-bbz)(H2O)2] (4).
hydrogen bonds, p–p and d10–d10 (aurophilic/argentophilic)
Introduction
interactions.3
Almost twenty years ago, Robson formulated and illustrated
one of the most powerful synthetic strategies in designing
coordination polymers: the node-and-spacer approach.1 The
clever choice of the metal ions, according to their stereo-
chemical preference, and the possibility to synthesize a large
variety of exo-dentate (divergent) organic ligands (rigid or
flexible, bi- or polydentate, symmetric or dissymmetric)
afforded a plethora of coordination polymers with various
dimensionalities and topologies.2 The peculiarity of the crystal
engineering of hybrid inorganic–organic frameworks arises
from the use of metal ions that exert a double function: a
structural one (directing and sustaining the network topology)
and a functional one (carrying the magnetic, optical, redox or
catalytic properties). The architecture of the crystals results
from a subtle interplay of organizing forces, the leading role
being played by the strong directionality of the metal–ligand
coordination bonds. Other non-covalent forces involved in
sustaining the supramolecular solid-state architectures are
Most of the reported coordination polymers are constructed
from monometallic nodes. Recently, we and others have
shown that oligonuclear complexes can also act as nodes.4
The metal ions interact with the divergent ligand through their
easily accessible coordination sites. The presence of two or
more metal ions, either identical or different, confers to the
node a higher geometrical flexibility. Moreover, the metal–metal
intra- and inter-node interactions can lead to new properties.
Taking the case of binuclear nodes, both metal ions or only
one of them can be involved in the interaction with the spacers
(Scheme 1). When the two metal ions differ drastically in their
chemical behaviour (one hard and the other one a soft acid),
then various coordination polymers can result from the selective
interaction of the metal ions with the spacers.4c This is valid
especially for [3d–4f] nodes.5 We have obtained such nodes by
employing dissymmetric compartmental ligands (Scheme 2).
This family of ligands was successfully designed by Costes in
order to obtain binuclear 3d–4f complexes.6 Recently, we and
others observed that these ligands are able to accommodate
different 3d metal ions as well.7 Herein, we report on new
heterobimetallic coordination polymers that are obtained by
using such 3d–3d0 nodes and dicarboxylato spacers: the
dianion of the 4,40-oxy-bis(benzoic) acid (oxy-bbz2ꢀ), the
a University of Bucharest, Faculty of Chemistry, Inorganic Chemistry
Laboratory, Str. Dumbrava Rosie nr. 23, 020464-Bucharest,
Romania. E-mail: marius.andruh@dnt.ro
b Laboratory of Molecular Magnetism, Dipartimento di Chimica e
dianion of the 2,5-dihidroxy-terephthalic acid (2,5-dhtp2ꢀ
and the oxalato ligand (ox2ꢀ).
)
`
UdR INSTM di Firenze, Universita degli Studi di Firenze,
Polo Scientifico, Via della Lastruccia 3, 50019 Sesto Fiorentino,
Firenze, Italy
c
´
Laboratoire Chimie et Ingenierie Moleculaire (CIMA),
UMR 6200 CNRS-Universite d’Angers, UFR Sciences, Bat. K,
´
´
ˆ
Results and discussion
2 Bd. Lavoisier, 49045 Angers, France
w Dedicated to Professor Herbert W. Roesky, on the occasion of his
75th birthday.
1
Three new coordination polymers
(
N[L(H2O)CuCo-
(oxy-bbz)]ꢁCH3CNꢁC2H5OH, 1N[L(H2O)CuCo(2,5-dhtp)]ꢁCH3CN
z This article is part of a themed issue on Coordination polymers:
1
structure and function.
and N[L(H2O)CuMn(ox)]ꢁ3H2O) have been constructed
from the following heterometallic nodes: [LCuMn]2+ and
[LCuCo]2+ (L2ꢀ is the dianion of the Schiff base resulted
from the 2 : 1 condensation of 3-methoxysalicyladehyde with
y Electronic supplementary information (ESI) available: Further
experimental data. CCDC reference numbers 772170–772175. For
ESI and crystallographic data in CIF or other electronic format see
DOI: 10.1039/c0nj00238k
c
This journal is The Royal Society of Chemistry and the Centre National de la Recherche Scientifique 2010 New J. Chem., 2010, 34, 2479–2490 2479

View Article Online
Fig.
1
Molecular structure for the binuclear precursor:
[LCuCo(NO3)2] 1.
Scheme 1
In order to obtain new coordination polymers based on the
nodes [CuCo] and [CuMn], we followed the same general
synthetic procedure, which consists of the slow diffusion of
the [LCuM(NO3)2] or [LCuM(ClO4)2] precursor, generated
in situ through the reaction between the mononuclear copper(II)
complex and the nitrate or the perchlorate of the second metal
ion (CoII, MnII), into a solution of the corresponding poly-
carboxylic acid fully deprotonated by lithium hydroxide.
Let us start with the crystal structure of the coordination
polymer constructed from the [LCuCo] node and the dianion
of the 4,40-oxy-bis(benzoic) acid (oxy-bbz2ꢀ) as a spacer:
1
N[L(H2O)CuCo(oxy-bbz)]ꢁCH3CNꢁC2H5OH 3. Within the
{CuCo} heterobinuclear unit, the copper(II) ion occupies the
inner N2O2 compartment of the Schiff base ligand, while the
cobalt(II) ion is hosted into the external O2O02 compartment of
the same ligand (Fig. 2). The copper(II) is pentacoordinated
within a square-pyramidal geometry, the basal plane being
formed by the four atoms of the N2O2 compartment
(Fig. 2a). The apical position is occupied by one aqua ligand
[Cu1–O10 = 2.306(3) A]. There are six oxygen atoms
surrounding the cobalt(II) ion (Fig. 2a): four atoms from the
O2O02 compartment of the Schiff base ligand [two short
Co1–O bonds, Co1–O2 = 2.022(3), Co1–O3 = 2.025(3) A,
involving the O(phenoxo) atoms and two long bonds involving the
methoxy groups: Co1–O1 = 2.407(3) and Co1–O4 = 2.461(3) A]
and two other oxygen atoms from carboxylato groups
Scheme 2
1,3-propanediamine). Binuclear nodes are formed through the
interaction of the mononuclear precursor [LCu] with the
second metal ion in the presence of the organic spacer.
The in situ formation of heterobinuclear nodes prompted us
to check whether it is possible to synthesize and isolate the
binuclear complexes themselves. The reaction between the
mononuclear copper(II) complex [LCu], cobalt(II) nitrate
and, respectively, manganese(II) nitrate, affords, after slow
evaporation of the solvents, single crystals of compounds
[LCuCo(NO3)2] (1) and [LCuMn(NO3)2] (2), which are
isomorphous. The crystal structure of compound 1 is depicted
in Fig. 1. In both binuclear complexes, the copper(II) ion is
hosted into the N2O2 compartment, displaying a square-
planar geometry. The cobalt(II) and manganese(II) ions in 1
and, respectively, 2 are hosted into the outer O2O02 compartment
of the ligand. Both are heptacoordinated by four oxygen
atoms arising from the organic ligand, and by three oxygen
atoms from one chelating and one monodentate nitrato group.
In compound 1, the Co–O distances vary between 2.038(3) and
2.405(3) A, with long Co–O(methoxy) bonds. The Mn–O
distances in crystal 2 vary between 2.1830(18) and 2.384(2) A.
The two long distances correspond to Mn–O(methoxy) bonds.
The distances between the metal ions in 1 and 2 are, respectively:
Cuꢁ ꢁ ꢁCo = 3.1982(8) and Cuꢁ ꢁ ꢁMn = 3.3219(6) A. Selected
bond distances are collected in Table 1.
Table 1 Selected bond distances for compounds 1 and 2
Compound
1
2
Bond length/A
Co1–O1 = 2.367(3)
Co1–O2 = 2.063(2)
Co1–O3 = 2.089(3)
Co1–O4 = 2.405(3)
Co1–O5 = 2.038(3)
Co1–O8 = 2.257(3)
Co1–O9 = 2.094(3)
Cu1–O2 = 1.935(2)
Cu1–O3 = 1.926(3)
Cu1–N1 = 1.969(3)
Cu1–N2 = 1.979(3)
Mn1–O1 = 2.369(2)
Mn1–O2 = 2.1830(18)
Mn1–O3 = 2.185(2)
Mn1–O4 = 2.384(2)
Mn1–O5 = 2.192(3)
Mn1–O8 = 2.343(3)
Mn1–O9 = 2.267(3)
Cu1–O2 = 1.9315(18)
Cu1–O3 = 1.9317(19)
Cu1–N1 = 1.969(2)
Cu1–N2 = 1.978(2)
c
2480 New J. Chem., 2010, 34, 2479–2490 This journal is The Royal Society of Chemistry and the Centre National de la Recherche Scientifique 2010

View Article Online
Fig. 2 Crystal structure of 1N[L(H2O)CuCo(oxy-bbz)]ꢁCH3CNꢁC2H5OH (3): asymmetric unit and atom numbering scheme (a); view of a helical
chain (b); packing diagram showing chains of opposite chiralities.
0
Fig. 3 Details of the packing diagram for crystal 3: intra- and intermolecular hydrogen bonds—symmetry transformations: = 1.5 ꢀ x, 0.5 + y,
00
1.5 ꢀ y; = ꢀ0.5 + x, 0.5 ꢀ y, ꢀ0.5 + z (a); supramolecular layers resulting from connecting the chains through hydrogen bonds and p–p
stacking interactions (b).
c
This journal is The Royal Society of Chemistry and the Centre National de la Recherche Scientifique 2010 New J. Chem., 2010, 34, 2479–2490 2481

View Article Online
[Co1–O5 = 1.982(3) and Co1–O80 = 1.947(3) A (0 = 1.5 ꢀ x,
0.5 + y, 1.5 ꢀ y). The 4,40-oxybis(benzoato) anion is
coordinated to two cobalt(II) ions from different nodes
through two oxygen atoms, one from each carboxylato group.
One of the uncoordinated oxygen atoms of the 4,40-oxybis-
(benzoate) anion, O7, forms an intramolecular hydrogen
bond with the water molecule coordinated to copper
[O70ꢁ ꢁ ꢁO10 = 2.772(5) A].
The shape of the spacer is angular, with the value of the
C24–O9–C27 angle equal to 117.1(3)1. Previous work on
V-shaped dicarboxylates, such as the 4,40-oxybis(benzoate)
anion, have shown that by employing this spacer to link metal
ions preferring tetrahedral environments, helical structures are
obtained.8 In compound 3, taking into account only the short
metal–ligand interactions, the stereochemistry of the cobalt
ion can be described as being tetrahedral. Consequently, the
individual chains in 3 are chiral (Fig. 2b). Since 3 crystallizes in
a centrosymmetric space group, the crystal contains chains
of opposite helicities. These chains are connected through
hydrogen bonds (Fig. 3a) established between the aqua ligand
coordinated to a copper ion from one chain and a non-
coordinated carboxylato 00 oxygen from another chain
[O10ꢁ ꢁ ꢁO600 = 2.757(4) A; = ꢀ0.5 + x, 0.5 ꢀ y, ꢀ0.5 + z]
resulting in supramolecular layers which are parallel to the
bc crystallographic plane (Fig. 3b). We recall that the aqua
ligand is involved in two hydrogen bonds, one intra- and the
other one intermolecular. The stability of supramolecular
layers is reinforced by p–p stacking interactions established
between the aromatic fragments of both valpn2ꢀ and
oxy-bbz2ꢀ ligands from neighbouring chains.
Fig. 4 Crystal structure of compound 4.
4,40-oxybis(benzoato) ligand into the apical position. The
percentage of trigonal distortion from square-pyramidal geometry
is described by the t parameter, defined as [(y ꢀ j)/60]ꢂ100,
where y and j are the angles between the donor atoms forming
the plane in a square-pyramidal geometry.9 The value of the
t parameter for the coordination polyhedron of copper(II) in 4
is 0.22 (t = 0 for an ideal square-planar geometry and t = 1
for an ideal trigonal bipyramidal geometry), indicating a
significant distortion from the square-pyramidal geometry.
The manganese(II) ion is heptacoordinated and displays a
distorted pentagonal bipyramidal geometry. The equatorial
plane is formed by five oxygen atoms, four atoms provided by
the O2O02 compartment of the organic ligand and another one
from
a coordinated water molecule, whereas the axial
positions are occupied by oxygen atoms, one from the
carboxylato group of the 4,40-oxybis(benzoato) anion, and
the second one from another coordinated water molecule. The
Mn–O(methoxy) bonds are quite long: Mn1–O1 = 2.5357(19)
and Mn1–O4 = 2.5569(16) A]. If we neglect them, then a more
appropriate description of the manganese environment should
be trigonal bipyramidal. The binuclear entities are inter-
connected through hydrogen bonds established between the
water molecules coordinated at the manganese(II) ions and the
uncoordinated carboxylate groups belonging to the neighbouring
complexes, resulting in a 2D supramolecular architecture (Fig. 5).
Each water molecule is involved in hydrogen interactions with
Interestingly, the interaction of the [CuMn] node with the
oxy-bbz2ꢀ anion leads to a completely different structure: a
discrete complex is obtained with only one carboxylato group
coordinated to both metal ions from the binuclear node
(syn–syn bridging mode): [LCuMn(oxy-bbz)(H2O)2] (4)
(Fig. 4), The copper ion is characterized by a distorted
square-pyramidal geometry, with the four atoms of the inner
N2O2 compartment of the Schiff base ligand in the basal
plane, and an oxygen atom from the carboxylato group of
0
Fig. 5 Packing diagram 0i0n0 crystal 4 showing the supramolecular layers formed by hydrogen bonds (symmetry transformations: = ꢀ1 + x, y,
00
1 + z; = ꢀx, ꢀy, ꢀz;
= ꢀx, ꢀ1 ꢀ y, ꢀz).
c
2482 New J. Chem., 2010, 34, 2479–2490 This journal is The Royal Society of Chemistry and the Centre National de la Recherche Scientifique 2010

View Article Online
Fig. 6 Crystal structure of compound 5: asymmetric unit and numbering scheme (a); perspective view of the 1-D coordination polymer (b).
two oxygen atoms from two different carboxylate groups
[O9ꢁ ꢁ ꢁO70=2.6686(18), O9ꢁ ꢁ ꢁO700=2.8734(18), O10ꢁ ꢁ ꢁO80=
longer [Cu2–O11 = 2.4136(24) A] than the other four bonds in
the basal plane [Cu2–N1 = 1.980(3); Cu2–N2 = 1.975(3);
Cu2–O2 = 1.9550(18); Cu2–O3 = 1.9634(18) A]. The
coordination sphere of the cobalt ion is formed by four oxygen
atoms provided by the valpn2ꢀ ligand [Co1–O1 = 2.4892(21);
Co1–O4 = 2.5427(22); Co1–O2 = 2.0047(19); Co1–O3 =
2.0172(18) A] and other two oxygen atoms from the carboxylato
groups of two 2,5-dihydroxy-terephtalato anions [Co1–O7 =
1.950(2) A; Co1–O5 = 1.992(2) A]. As in the other cases of
binuclear complexes derived from this ligand, the methoxy
groups are weakly bonded to the second 3d metal ion.
0
2.6765(18), O10ꢁ ꢁ ꢁO80 0 0=2.6933(19) A;
= ꢀ1 + x, y,
00
0 00
1 + z; = ꢀx, ꢀy, ꢀz;
= ꢀx, ꢀ1 ꢀ y, ꢀz].
The interaction of the [LCuCo]2+ node with the dianion the
2,5-dihidroxy-terephthalic acid (2,5-dhtp2ꢀ) affords a 1-D
1
coordination polymer: N[L(H2O)CuCo(2,5-dhtp)]ꢁCH3CN
(5). The heterobinuclear {CuCo} nodes are connected by
2,5-dihydroxy-terephtalato anions via the cobalt(II) ions
generating infinite zigzag chains (Fig. 6). The cobalt(II) ion is
hosted into the external O2O02 compartment of the organic
ligand. The coordination sphere of the Cu(II) ion is formed by
the four atoms of the N2O2 compartment in the basal
plane and another oxygen atom from the aqua ligand
coordinated in the apical position, and its geometry can be
characterized as square-pyramidal. The apical Cu–O bond is
Each carboxylato group is coordinated to a cobalt ion
through one oxygen atom. The two hydroxo groups of the
2,5-dihydroxy-terephtalato spacer did not increase the
dimensionality of the system via hydrogen bonds, the only
hydrogen bond in which each HO group is involved being an
c
This journal is The Royal Society of Chemistry and the Centre National de la Recherche Scientifique 2010 New J. Chem., 2010, 34, 2479–2490 2483

View Article Online
Fig. 7 Packing diagram in crystal 5: intra- and intermolecular hydrogen bonds—symmetry transformation: 0 = ꢀ1 ꢀ x, 2 ꢀ y, ꢀz (a); perspective
view of a brick wall supramolecular layer (b).
intramolecular one [O9ꢁ ꢁ ꢁO5 = 2.569(3) A], where the hydroxy
group acts as a donor toward the oxygen atom of the closest
carboxylato group, coordinated at the Co(II) ion. Each aqua
ligand coordinated to the copper(II) ion forms hydrogen
bonds: an intramolecular interaction, with the uncoordinated
oxygen atom of the carboxylato group from the nearby spacer
[O11ꢁ ꢁ ꢁO6 = 2.709(4) A], and an intermolecular one with the
aqua ligand [O11ꢁ ꢁ ꢁO110 = 2.876(3) A; 0 = ꢀ1 ꢀ x, 2 ꢀ y, ꢀz]
from the neighbouring zig-zag chain (Fig. 7a). A 2-D supra-
molecular sheet with a (6,3) brick wall topology is developed
within the bc crystallographic plane (Fig. 7b).
intense band located at B600 nm is characteristic for cobalt(II)
complexes with a tetrahedral geometry, being ascribed to the
4A2
-
4T1(P) transition. Another characteristic band for
tetrahedral cobalt(II) complexes is located in the near-infrared
region, which is assigned to the 4A2 4T1(F) transition.
-
When the symmetry of the cobalt(II) ion decreases from Td
to C2v, the 4T1(F) term is split into 4A2 + 4B1 + 4B2 levels and
three bands are expected. Indeed, in the NIR region, both
compounds show broad bands between 1000 and 2000 nm,
each band with three not-well defined maxima. Consequently,
the stereochemistry of the cobalt(II) ion in compounds 3 and 5
can be described as being (pseudo)tetrahedral, with a symmetry
close to C2v.
A useful tool to diagnose the stereochemistry of the cobalt(II)
ion is the UV-vis spectroscopy.10 The diffuse reflectance
spectra of compounds 3 and 5 are a superposition of the
absorption bands of the two chromophores (Fig. 8). The
The ability of the oxalato anion to generate homo- and
heteropolynuclear complexes with various nuclearities or
c
2484 New J. Chem., 2010, 34, 2479–2490 This journal is The Royal Society of Chemistry and the Centre National de la Recherche Scientifique 2010

View Article Online
generating infinite chains running along the crystallo-
graphic b axis. The oxalato ions exhibit a second bridging
mode: chelated to one manganese ion and monodenatate to
another (Fig. 9a). The copper(II) ion is surrounded by five
atoms, four atoms from the N2O2 compartment of the
Schiff base ligand defining the basal plane and one water
molecule in the apical position, resulting in a slightly distorted
square-pyramidal geometry (Fig. 9b). The value of the
t
parameter (0.06) indicates an insignificant distortion
from the ideal square-pyramidal geometry. The manganese(II)
ions are heptacoordinated, the coordination sphere being
formed by the four oxygen atoms provided by the
0
O2O2 compartment of the organic ligand and other three
oxygen atoms from two oxalato anions (Fig. 10a). Again the
Mn–O(methoxy) distances, Mn1–O1 = 2.413(2) and Mn1–O4 =
2.424(2) A, are longer than the other Mn–O distances. The
Cuꢁ ꢁ ꢁMn separation through the bridging phenoxo oxygen
atoms of the valpn2ꢀ ligand is equal to 3.339(1) A.
The distance between the oxalato-bridged manganese ions is
5.858(2) A.
Fig. 8 Diffuse reflectance spectra if compounds 3 and 5.
Apart from the aqua ligand coordinated at the copper(II)
ion, there are three other crystallization water molecules per
heterobinuclear {CuMn} unit. The coordinated water
molecule is involved in two intramolecular hydrogen bonds
with vicinal oxygen atoms provided by two oxalato spacers,
one atom uncoordinated (O1W00ꢁ ꢁ ꢁO70 = 2.78 A; 0 = 0.5 ꢀ x,
0.5 + y, 0.5 ꢀ z; 00 = 0.5 ꢀ x, ꢀ0.5 + y, 0.5 ꢀ z) and the other
one coordinated to the manganese ion (O1W00ꢁ ꢁ ꢁO5 = 2.82 A)
(Fig. 10a). In the crystallographic ab plane, the chains
dimensionalities is well known.11 There are two common
bridging modes exhibited by the oxalato ligand: (i) bis-chelating
toward two metal centers; (ii) bidentate chelating toward
one metal ion and monodentate toward the second one. The
2ꢀ
self-assembly process involving [LCuMn]2+ and C2O4
ions affords an oxalato-bridged coordination polymer:
N[L(H2O)CuMn(ox)]ꢁ3H2O (6). The oxalato anion connects
the binuclear {CuMn} nodes through the manganese(II) ions,
0
1
2
Fig. 9 Crystal structure of 6: view of the asymmetric unit along with the atom numbering scheme (a)
=
ꢀ x, 12 + y, 12 ꢀ z; view of a chain (b).
c
This journal is The Royal Society of Chemistry and the Centre National de la Recherche Scientifique 2010 New J. Chem., 2010, 34, 2479–2490 2485

View Article Online
Fig. 10 Details of the packing diagram for crystal 6: hydrogen bonds involving the coordinated and uncoordinated water molecules (a);
perspective view of a supramolecular layer (b).
are interconnected into a 2D supramolecular layer through
a complex system of hydrogen bonds established between
the crystallization water molecules (O2W0ꢁ ꢁ ꢁO70=2.87,
In a
previous paper,7b we investigated the magnetic
properties of coordination polymers constructed from binuclear
[CuMn] nodes connected by dicarboxylato and [Ni(CN)4]2ꢀ
spacers. Since the distance between the nodes is quite large, the
interaction between the resulting spins (S = 2, antiferromagnetic
intranode coupling) was found to be extremely weak, according
to the Weiss constant we found in these complexes. Complex 6
seems to be more interesting from this point of view because
the binuclear nodes are linked by a shorter spacer (ox2ꢀ).
The temperature dependence of the wMT product (wM is the
magnetic susceptibility per CuIIMnII unit) is similar to those
O2W0ꢁꢁꢁO3W0=2.84, O3W0ꢁꢁꢁO4W0=2.85, O4W0ꢁꢁꢁO2W0 00 0
=
2.76, O2W0ꢁ ꢁ ꢁO4W0 00 = 2.76 A; 00 0 = 1 + x, y, z; 0 00 0 = 1 + x,
1 + y, z) (Fig. 10b). The hydrogen bonded crystallization
water molecules form helical chains, which show both P and
M chiralities (Fig. 11). Other chains made by hydrogen
bonded water molecules, including helical chains, have been
reported recently in the literature.12 Selected bond distances
for compounds 3–6 are given in Table 2.
c
2486 New J. Chem., 2010, 34, 2479–2490 This journal is The Royal Society of Chemistry and the Centre National de la Recherche Scientifique 2010

View Article Online
Fig. 11 Packing diagram in crystal 6 showing the hosted water
chains.
Fig. 12
wMT vs. T curve for compound 6.
observed with other complexes in this family (Fig. 12). The
room temperature value of the wMT product is 4.15 cm3 molꢀ1 K,
lower than that expected (4.75 cm3 molꢀ1 K) for a [CuMn] pair
with uncoupled ions (assuming gCu = gMn = 2), suggesting
that the intra-node antiferromagnetic interaction is effective
even at room temperature. By lowering the temperature,
wMT decreases continuously down to 50 K, reaching a plateau,
then it decreases abruptly. This behavior can be interpreted as
follows: upon cooling, the CuII and MnII ions within each
node are antiferromagnetically coupled. Indeed, the observed
plateau corresponds to S = 2 (3.03 = cm3 molꢀ1 K).
The further decrease of the temperature is due to the
intrachain antiferromagnetic interactions of the S = 2 spins
and, eventually, to the zero-field splitting effect within the
S = 2 spin state. For the CuII (S = 21)–MnII (S = 5/2) system,
the energies of the low-lying spin states are obtained by using
the isotropic spin Hamiltonian: H = ꢀJSMnSCu, which leads
to the following equation describing the temperature
dependence of susceptibility, wM:
The Weiss term, y, was included in order to take into
account the inter-node and other intermolecular interactions.
A least-squares fit to the data leads to the following values:
J = ꢀ71.6 cmꢀ1; g = 2.06; y = ꢀ1.56 K. The Weiss constant
is sensibly higher than the values found for [LCuMn(pzdc)-
(CH3OH)(H2O)]ꢁH2O (y = ꢀ0.41 K) and [LCu(CH3OH)-
(H2O)Mn(NC)2Ni(CN)2]ꢁ(H2O)(CH3CN) (y = ꢀ0.39 K),7b
suggesting, as expected, a stronger inter-node antiferromagnetic
interaction (pzdc2ꢀ = the dianion of the pyrazole-3,5-
dicarboxylic acid). The strength of the inter-node coupling
(J0 = ꢀ0.27 cmꢀ1) has been estimated by using the following
equation: y = zꢁJ0ꢁS(S + 1)/3k, where z = 2 (z is the number
of nearest neighbors) and S = 2. This is valid assuming that
the magnetic interaction between the chains is negligible.
Alternatively, the data below 50 K have been fitted through
the Fisher equation for a classical uniform chain of local spin
quintets:13
ꢀ
ꢁ
Ng2b2
3k
1 þ u
1 ꢀ u
wMT ¼
SðS þ 1Þ ꢁ
wM = [2Nb2g2/k(T ꢀ y)]([5 + 14 exp(x)]/[5 + 7 exp(x)];
with x = 3J/kT.
with u = coth[J0S(S + 1)/kT] ꢀ [kT/J0S(S + 1)] and S = 2.
Table 2 Selected bond distances for compounds 3–6a
Compound
3
4
5
6
Bond length/A
Co1–O8 = 1.947(3)
Co1–O5 = 1.982(3)
Co1–O2 = 2.022(3)
Co1–O3 = 2.025(3)
Co1–O1 = 2.407(3)
Co1–O4 = 2.461(3)
Cu1–N1 = 1.977(3)
Cu1–N2 = 1.981(3)
Cu1–O2 = 1.956(3)
Cu1–O3 = 1.944(2)
Cu1–O10 = 2.306(3)
Mn1–O10 = 2.1230(13)
Mn1–O5 = 2.1260(13)
Mn1–O3 = 2.1485(13)
Mn1–O2 = 2.1946(13)
Mn1–O9 = 2.1998(14)
Mn1–O1 = 2.5357(19)
Mn1–O4 = 2.5569(16)
Cu1–N1 = 1.9730(16)
Cu1–N2 = 2.0050(18)
Cu1–O2 = 1.9755(14)
Cu1–O3 = 1.9336(12)
Cu1–O6 = 2.2947(14)
Co1–O7 = 1.950(2)
Co1–O5 = 1.992(2)
Co1–O2 = 2.0047(19)
Co1–O3 = 2.0172(18)
Co1–O1 = 2.4892(21)
Co1–O4 = 2.5427(22)
Cu2–N1 = 1.980(3)
Cu2–N2 = 1.975(3)
Cu2–O2 = 1.9550(18)
Cu2–O3 = 1.9634(18)
Cu2–O11 = 2.414(3)
Mn1–O1 = 2.413(2)
Mn1–O2 = 2.179(2)
Mn1–O3 = 2.1994(19)
Mn1–O4 = 2.424(2)
Mn1–O5 = 2.241(2)
Mn1–O6 = 2.165(2)
Mn1–O80 = 2.134(2)
Cu1–N1 = 1.973(3)
Cu1–N2 = 2.000(2)
Cu1–O2 = 1.9855(19)
Cu1–O3 = 1.931(2)
Cu1–O1W = 2.269(2)
a
0
Symmetry code: = 0.5 ꢀ x, 0.5 + y, 0.5 ꢀ z.
c
This journal is The Royal Society of Chemistry and the Centre National de la Recherche Scientifique 2010 New J. Chem., 2010, 34, 2479–2490 2487

View Article Online
Table 3 Crystallographic data, details of data collection and structure refinement parameters for compounds 1–6
Compound
1
2
3
Chemical formula
M/g molꢀ1
Temperature/K
C19H20CoCuN4O10
586.86
293(2)
C19H20CuMnN4O10
582.87
293(2)
C37H39CoCuN3O11
824.18
200(2)
Wavelength/A
Crystal system
Space group
a/A
b/A
c/A
a (1)
0.71073
Triclinic
0.71073
Triclinic
0.71073
Monoclinic
P21/n
10.5871(16)
20.8938(11)
16.6956(16)
90
107.580(10)
90
3520.7(7)
4
1.555
1.143
1704
1.036
0.0538, 0.1320
0.0977, 0.1560
1.081, ꢀ0.744
ꢀ
P1
ꢀ
P1
8.5076(15)
11.190(2)
11.3624(18)
82.947(13)
83.930(13)
84.633(14)
1063.9(3)
2
1.832
1.847
596
1.013
8.6001(10)
11.2045(15)
11.3972(13)
83.875(10)
84.626(9)
84.262(10)
1082.7(2)
2
1.788
1.632
592
1.083
b (1)
g (1)
V/A3
Z
Dc/g cmꢀ3
m/mmꢀ1
F(000)
Goodness-of-fit on F2
Final R1, wR2 [I > 2s(I)]
R1, wR2 (all data)
Largest diff. peak and hole/e Aꢀ3
0.0621, 0.1428
0.1211, 0.1733
0.699, ꢀ0.724
0.0565, 0.1066
0.0900, 0.1174
0.373, ꢀ0.742
Compound
4
5
6
Chemical formula
M/g molꢀ1
Temperature/K
C33H32CuMnN2O11
751.09
293(2)
C29H29CoCuN3O11
717.98
293(2)
C21H28CuMnN2O12
618.87
293(2)
Wavelength/A
Crystal system
Space group
a/A
b/A
c/A
a (1)
0.71073
Triclinic
0.71073
Triclinic
0.71073
Monoclinic
P21/n
15.236(5)
10.124(5)
15.653(5)
90
93.066(5)
90
2411.0(16)
4
1.683
1.474
1240
1.117
0.0505, 0.1391
0.0649, 0.1548
1.641, ꢀ0.722
ꢀ
P1
ꢀ
P1
9.7256(6)
10.3820(6)
16.7920(10)
73.999(4)
73.386(5)
89.498(5)
1557.26(16)
2
1.602
1.155
772
1.026
9.8331(15)
11.3315(16)
13.8667(19)
99.618(11)
96.924(12)
93.266(12)
1507.6(4)
2
1.571
1.321
726
1.021
b (1)
g (1)
V/A3
Z
Dc/g cmꢀ3
m/mmꢀ1
F(000)
Goodness-of-fit on F2
Final R1, wR2 [I > 2s(I)]
R1, wR2 (all data)
Largest diff. peak and hole/e Aꢀ3
0.0442, 0.0952
0.0646, 0.1026
0.613, ꢀ1.031
0.0594, 0.1316
0.1067, 0.1529
0.651, ꢀ0.901
The best fit to the data (Fig. S1y) gives J0 = ꢀ0.21 cmꢀ1
,
Experimental section
a value that is close to the one obtained from the Weiss
constant.
Physical measurements
IR spectra were recorded on a Tensor 37 Bruker spectro-
photometer in the 4000–400 cmꢀ1 range. Samples were run as
KBr pellets. Diffuse reflectance UV-VIS-NIR spectra have
been recorded with a JASCO V670 instrument.
Conclusions
Herein, we have illustrated with new examples that hetero-
bimetallic 3d–3d0 nodes can efficiently act as nodes for designing
coordination polymers. In principle, the spacers can interact
with only one type of metal ion from different nodes, while the
second metal ion from the nodes is not involved in the linkage,
can connect one type of metal ion from a node with another
type from the next node, or can connect both metal ions from
a node with the two metal ions from another node (Scheme 1).
In the examples we have presented here, only the second metal
ion (CoII, MnII), which is hosted in the large compartment,
interacts with the spacers.
X-Ray structure determination
X-Ray diffraction measurements were performed on a STOE
IPDS II diffractometer for the compounds 1, 2, 4 and 5, on a
Nonius Kappa CCD diffractometer for the compound 3 and
Oxford Xcalibur 3 CCD diffractometer for the compound 6,
operating with Mo-Ka (l = 0.71073 A) X-ray tube with
graphite monochromator. The structures were solved by direct
methods and refined by full-matrix least squares techniques
based on F2. The non-H atoms were refined with anisotropic
c
2488 New J. Chem., 2010, 34, 2479–2490 This journal is The Royal Society of Chemistry and the Centre National de la Recherche Scientifique 2010

View Article Online
1
displacement parameters. Calculations were performed using
SHELX-97 crystallographic software package. A summary of
the crystallographic data and the structure refinement for
crystal 1–6 are given in Table 3.y
N[L(H2O)CuCo(2,5-dhtp)]ꢁCH3CN (5).
A
solution of
[Cu(valpn)(H2O)] (0.02 mmol) in acetonitrile : ethanol was
reacted with solid Co(NO3)2 (0.02 mmol). Green-blue crystals
of 5 were obtained upon slow diffusion, in a test tube, through
an ethanol–water layer (1 mL), of the resulted mixture into an
ethanol–water solution of the 2,5-dihidroxy-terephtalic acid
(0.02 mmol) deprotonated by LiOH (0.04 mmol). IR bands
(KBr, cmꢀ1): 3440 s, 3328 vw, 3059 vw, 3014 vw, 2965 vw,
2932 w, 2835 ws, 1621 vi, 1565 w, 1475 i, 1452 i, 1425 i, 1363 w,
1320 m, 1297 i, 1248 vi, 1231 vi, 1104 w, 1075 m, 988 vw,
955 vw, 934 vw, 906 vw, 856 w, 814 w, 785 m, 742 m, 644 w,
614 w, 551 w, 473 vw, 442 vw, 418 vw.
Synthesis of [LCuCo(NO3)2] (1), [LCuMn(NO3)2] (2),
1
N[L(H2O)CuCo(oxy-bbz)]ꢁCH3CNꢁC2H5OH (3),
1
[LCuMn(oxy-bbz)(H2O)2] (4), N[L(H2O)CuCo(2,5-dhtp)]ꢁ
CH3CN (5) and N[L(H2O)CuMn(ox)]ꢁ3H2O (6)
All starting materials were of reagent grade and were
used without further purification. The [LCu] precursor
[L2ꢀ = N,N0-propylene-bis-(3-methoxysalycilideneiminato)] was
prepared following the procedure published by Pfeiffer et al.14
1
N[L(H2O)CuMn(ox)]ꢁ3H2O (6).
A solution of [LCu]
[LCuCo(NO3)2] (1). A solution of [LCu] (3 mmol) in
acetonitrile : ethanol was reacted with solid Co(NO3)2ꢁ6H2O
(3 mmol) and stirred for 15 min. Green-blue crystals were
obtained upon slow evaporation of the resulted mixture. IR
bands (KBr, cmꢀ1): 3094 ws, 3065 vw, 2996 vw, 2942 ws, 2927
vw, 2860 ws, 2845 vw, 1613 vi, 1563 w, 1506 m, 1471 i, 1440 i,
1408 m, 1384 m, 1329 m, 1298 vi, 1284 i, 1248 m, 1234 i, 1175 w,
1102 vw, 1070 m, 1026 w, 955 vw, 857 w, 786 w, 746 m, 642 w,
616 w, 572 vw, 538 vw, 471 vw, 444 vw.
(0.04 mmol) in acetonitrile : ethanol was reacted with solid
Mn(NO3)2ꢁ(H2O) (0.04 mmol). Green crystals of 6 were
obtained upon slow diffusion, in a test tube, through an
ethanol–water layer (1 mL), of the resulted mixture into an
aqueous solution of the potassium oxalate (0.04 mmol). IR
bands (KBr, cmꢀ1): 3424 s, 3264 ws, 3060 vw, 2944 ws,
2933 vw, 2921 ws, 2903 ws, 2835 vw, 1634 vi, 1622 vi, 1602
i, 1561 w, 1473 m, 1454 w, 1409 vw, 1369 vw, 1306 m, 1244 m,
1228 i, 1170 vw, 1101 vw, 1073 w, 1006 vw, 987 vw, 955 vw,
856 w, 779 w, 740 m, 637 vw, 613 vw, 565 vw, 508 vw, 469 vw,
438 vw.
[LCuMn(NO3)2] (2). A solution of [LCu] (3 mmol) in
acetonitrile : ethanol was reacted with solid Mn(NO3)2ꢁH2O
(3 mmol) and stirred for 15 min. Green-brown crystals were
obtained upon slow evaporation of the resulted mixture.
IR bands (KBr, cmꢀ1): 2998 vw, 2950 ws, 2929 w, 2855 vw,
1709 vw, 1614 vi, 1561 m, 1472 vi, 1439 i, 1409 m, 1384 w, 1331 w,
1302 vi, 1234 i, 1174 vw, 1101 vw, 1068 m, 1030 w, 985 vw,
953 vw, 933 vw, 856 w, 816 vw, 786 w, 747 i, 637 vw, 614 vw,
575 vw, 535 vw, 466 vw, 443 vw.
Acknowledgements
Financial support from CNCSIS (grant IDEI 1912/2009) is
gratefully acknowledged.
References
1 (a) R. W. Gable, B. F. Hoskins and R. Robson, J. Chem. Soc.,
Chem. Commun., 1990, 1677; (b) B. F. Hoskins and R. Robson,
J. Am. Chem. Soc., 1990, 112, 1546.
1
N[L(H2O)CuCo(oxy-bbz)]ꢁCH3CNꢁC2H5OH (3). A solution
of [LCu] (0.02 mmol) in acetonitrile : ethanol was reacted with
solid Co(NO3)2 (0.02 mmol). Green-blue crystals of 3 were
obtained upon slow diffusion, in a test tube, through an
ethanol–water layer (1 mL), of the resulted mixture into an
ethanol–water solution of the oxy-bis(benzoic acid) (0.02 mmol)
deprotonated by LiOH (0.04 mmol). IR bands (KBr, cmꢀ1):
3616 w, 3357 s, 3224 ws, 3091 vw, 2970 vw, 2939 w, 2916 vw,
2837 w, 1618 vi, 1560 i, 1546 i, 1483 m, 1469 i, 1436 w, 1416 w,
1394 w, 1368 i, 1312 i, 1249 i, 1230 i, 1173 w, 1153 w, 1105 w,
1073 m, 1010 w, 988 w, 955 vw, 854 w, 822 w, 789 w, 746 m, 716 m,
658 w, 637 w, 615 vw, 567 vw, 530 vw, 463 vw, 439 vw.
2 (a) R. Robson, J. Chem. Soc., Dalton Trans., 2000, 3735;
(b) N. R. Champness, Dalton Trans., 2006, 877; (c) B. Moulton
and M. J. Zaworotko, Chem. Rev., 2001, 101, 1629;
(d) M. Eddaoudi, D. B. Moler, H. Li, B. Chen, T. M. Reineke,
M. O’Keeffe and O. M. Yaghi, Acc. Chem. Res., 2001, 34, 319;
(e) S. Kitagawa, R. Kitaura and S. Noro, Angew. Chem., Int. Ed.,
2004, 43, 2334; (f) C. J. Kepert, Chem. Commun., 2006, 695;
(g) S. Kitagawa, S. Noro and T. Nakamura, Chem. Commun.,
2006, 701; (h) O. R. Evans and W. Lin, Acc. Chem. Res., 2002, 35,
511; (i) E. Coronado and J.-R. Galan-Mascaros, J. Mater. Chem.,
´ ´
2005, 15, 66; (j) D. Bradshaw, J. B. Claridge, E. J. Cussen,
T. J. Prior and M. J. Rosseinsky, Acc. Chem. Res., 2005, 38, 273;
(k) S. Kitagawa and S. Noro, in Comprehensive Coordination
Chemistry II, ed. J. A. McCleverty and T. J. Meyer, Elsevier,
Amsterdam, 2004, vol. 7, p. 231.
[LCuMn(oxy-bbz)(H2O)2] (4). A solution of [LCu] (0.03 mmol)
in acetonitrile : ethanol was reacted with solid Mn(ClO4)2ꢁ6H2O
(0.03 mmol). Green crystals of 4 were obtained upon slow
diffusion, in a test tube, through an ethanol–water layer
(1 mL), of the resulted mixture into an ethanol–water solution
of the 4,40-oxybis(benzoic) acid (0.03 mmol) deprotonated by
LiOH (0.06 mmol). IR bands (KBr, cmꢀ1): 3477 s, 3046 ws,
2976 vw, 2944 vw, 2922 vw, 2874 vw, 2842 vw, 1632 i, 1618 i,
1597 i, 1557 m, 1470 i, 1439 vw, 1373 vi, 1311 m, 1234 vi, 1165 m,
1151 w, 1101 vw, 1069 w, 1012 vw, 980 vw, 953 vw, 935 vw,
878 vw, 856 w, 824 vw, 785 w, 742 m, 703 m, 657 vw, 640 vw,
610 vw, 566 vw, 511 vw, 461 vw, 445 vw.
3 (a) H. W. Roesky and M. Andruh, Coord. Chem. Rev., 2003, 236,
91; (b) C. Janiak, J. Chem. Soc., Dalton Trans., 2000, 3885;
(c) H. Schmidbaur, Chem. Soc. Rev., 1995, 24, 391;
(d) A. M. Madalan, N. Avarvari and M. Andruh, Cryst. Growth
Des., 2006, 6, 1671 and references therein; (e) A. N. Khlobystov,
A. J. Blake, N. R. Champness, D. A. Lemenovskii, A. G. Majouga,
N. V Zyk and M. Schroder, Coord. Chem. Rev., 2001, 222, 155;
¨
(f) J. K. Katz, K. Sakai and D. B. Leznoff, Chem. Soc. Rev., 2008,
37, 1884; (g) A. M. Madalan, V. Ch. Kravtsov, Yu. A. Somonov,
V. Voronkova, L. L. Korobchenko, N. Avarvari and M. Andruh,
Cryst. Growth Des., 2005, 5, 45; (h) C. Paraschiv, M. Andruh,
S. Ferlay, M. W. Hosseini, N. Kyritsakas, J.-M. Planeix and
N. Stanica, Dalton Trans., 2005, 1195.
4 (a) F. A. Cotton, C. Lin and C. A. Murillo, Acc. Chem. Res., 2001,
34, 759; (b) M. Andruh, Pure Appl. Chem., 2005, 77, 1685;
c
This journal is The Royal Society of Chemistry and the Centre National de la Recherche Scientifique 2010 New J. Chem., 2010, 34, 2479–2490 2489

View Article Online
(c) M. Andruh, Chem. Commun., 2007, 2565 and references therein;
(d) M. Andruh, D. G. Branzea, R. Gheorghe and A. M. Madalan,
CrystEngComm, 2009, 11, 2571; (e) M. Pascu, M. Andruh,
Inorg. Chem., 1999, 38, 2698; (c) O. Castillo, A. Luque, J. Sertucha,
P. Roman and F. Lloret, Inorg. Chem., 2000, 39, 6142;
´
(d) M. Andruh, R. Melanson, C. V. Stager and F. D Rochon,
Inorg. Chim. Acta, 1996, 251, 309; (e) F. D. Rochon, R. Melanson
and M. Andruh, Inorg. Chem., 1996, 35, 6086; (f) M. C. Munoz,
M. Julve, F. Lloret, J. Faus and M. Andruh, J. Chem. Soc., Dalton
A. Muller and M. Schmidtmann, Polyhedron, 2004, 23, 673.
¨
5 (a) R. Gheorghe, P. Cucos, M. Andruh, J.-P. Costes,
B. Donnadieu and S. Shova, Chem.–Eur. J., 2006, 12, 187;
(b) R. Gheorghe, M. Andruh, A. Muller and M. Schmidtmann,
Inorg. Chem., 2002, 41, 5314.
¨
Trans., 1998, 3125; (g) R. Lescouezec, G. Marinescu,
¨
M. C. Munoz, D. Luneau, M. Andruh, F. Lloret, J. Faus,
6 J.-P. Costes, F. Dahan, A. Dupuis and J.-P. Laurent, Inorg. Chem.,
1996, 35, 2400.
7 (a) J.-P. Costes, R. Gheorghe, F. Dahan, M. Andruh, S. Shova and
J.-M. Clemente Juan, New J. Chem., 2006, 30, 572;
´
(b) D. G. Branzea, A. Guerri, O. Fabelo, C. Ruiz-Perez,
L.-M. Chamoreau, C. Sangregorio, A. Caneschi and M. Andruh,
Cryst. Growth Des., 2008, 8, 941; (c) D. G. Branzea, L. Sorace,
C. Maxim, A. Caneschi and M. Andruh, Inorg. Chem., 2008, 47,
6590.
8 O. Y. Ma, Z. Han and Y. He, Chem. Commun., 2007, 4107.
9 B. J. Hathaway, in Comprehensive Coordination Chemistry, ed. G.
Wilkinson, R. D. Gillard and J. A. McCleverty, Pergamon,
Oxford, 1987, vol. 5, p. 607.
M. Julve, J. A. Mata, R. Llusar and J. Cano, New J. Chem.,
2001, 25, 1224; (h) G. Marinescu, M. Andruh, R. Lescouezec,
¨
M. C. Munoz, J. Cano, F. Lloret and M. Julve, New J. Chem.,
2000, 24, 527; (i) S. Decurtins, H. W. Schmalle, H. R. Oswald,
A. Linden, J. Ensling, P. Gutlich and A. Hauser, Inorg. Chim.
¨
Acta, 1994, 216, 65; (j) S. Decurtins, H. W. Schmalle,
P. Schneuwly, J. Ensling and P. Gutlich, J. Am. Chem. Soc.,
¨
1994, 116, 9521; (k) Costisor, K. Mereiter, M. Julve, F. Lloret,
Y. Journaux, W. Linert and M. Andruh, Inorg. Chim. Acta, 2001,
324, 352.
12 (a) S. Neogi and P. K. Bhardway, Inorg. Chem., 2005, 44, 816;
(b) X.-L. Zhang, B.-H. Ye and X.-M. Chen, Cryst. Growth Des.,
2005, 5, 1609; (c) K. L. Huang, X. Liu, X. Chen and D.-Q. Wang,
Cryst. Growth Des., 2009, 9, 1646.
10 A. B. P. Lever, Inorganic Electronic Spectroscopy, Elsevier,
Amsterdam, 1984.
13 O. Kahn, Molecular Magnetism, VCH, New York, 1993, p. 258.
14 P. Pfeiffer, E. Breityh, E. Lulle and T. Tsumaki, Justus Liebigs Ann.
Chem., 1933, 503, 84.
11 See, for example: (a) G. De Munno, R. Ruiz, F. Lloret, J. Faus,
R. Sessoli and M. Julve, Inorg. Chem., 1995, 34, 408 and references
therein; (b) J. Y. Lu, M. A. Lawandy, J. Li, T. Yuen and C. L. Lin,
¨
c
2490 New J. Chem., 2010, 34, 2479–2490 This journal is The Royal Society of Chemistry and the Centre National de la Recherche Scientifique 2010