Self-assembly of dimeric MnIII-Schiff-base complexes tuned by perchlorate anions

Article abstract of DOI:10.1002/ejic.200700199

The synthesis and structural and spectroscopic characterisation of 12 manganese(III)-Schiff-base complexes of the formula [MnLⁿ(H ₂O/CH₃OH)₂](ClO₄)(mH₂O) (m = 0, 1) are described. The multi

Full text of DOI:10.1002/ejic.200700199

FULL PAPER
DOI: 10.1002/ejic.200700199
III
Self-Assembly of Dimeric Mn –Schiff-Base Complexes Tuned by Perchlorate
Anions
[
a]
[b]
[b]
Manuel R. Bermejo, M. Isabel Fernández,* Esther Gómez-Fórneas,
[b]
[b]
[a]
[b]
Ana González-Noya, Marcelino Maneiro,* Rosa Pedrido, and M. Jesús Rodríguez
Keywords: Manganese / Self-assembly / Anions / Schiff bases / Peroxidase
The synthesis and structural and spectroscopic characterisa-
tion of 12 manganese(III)–Schiff-base complexes of the for-
the inner compartment of the Schiff base to the equatorial
plane of the octahedron and by the binding of two water
n
mula [MnL (H
2
O/CH
3
OH)
2
](ClO
4 2
)(mH O) (m = 0, 1) are de- molecules in the axial positions. The octahedron entities are
n
scribed. The multidentate H
2
Ln and H
4
L Schiff-base ligands
linked in pairs by µ-aquo bridges between neighbouring ax-
ial water molecules and also by π–π stacking interactions, es-
tablishing dimeric structures. Perchlorate anions are accom-
modated in the cavities of the framework and form hydrogen
were obtained by condensation of different diamines (1,2-di-
aminoethane, 1,2-diamino-2-methylethane, 1,2-diamino-2,2-
dimethylethane, 1,3-diamino-2,2-dimethylpropane) and 2,3-
dihydroxybenzaldehyde,
3-methoxy-2-hydroxybenzalde- bonds with the aqua ligands, leading to infinite spirals of the
hyde or 3-ethoxy-2-hydroxybenzaldehyde. The crystal struc-
complexes generated by a screw axis along a. Moreover, the
peroxidase activity of the crystallographically solved com-
plexes 2 and 8, studied in the presence of the water-soluble
trap ABTS, agrees with the predicted rate according to the
activity/rhombicity correlation.
3
10
tures of H
2
L and H
4
L
ligands were solved by X-ray crystal-
lography, revealing their ability to bind metal centres.
Recrystallisation of complexes 2 and 8 from methanol yielded
2
8
single crystals of [MnL (H
ClO ). Their X-ray characterisation shows a tetragonally
elongated octahedral geometry for the manganese coordina-
2 2 4 2 2
O) ](ClO ) and [MnL (H O) ]-
(
4
(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim,
Germany, 2007)
2 2
tion sphere, formed by the chelation of the N O donor set of
Introduction
enzymes,[14] but studies focusing on their multidimensional
arrangements are less abundant. This paper presents new
results from our intention of studying in depth the multidi-
mensional arrangements of manganese(III) chemistry.
We have already shown how the introduction of chloride
Crystal engineering of supramolecular architectures sus-
tained by noncovalent intermolecular forces represents a
rapidly expanding field that offers potential for the develop-
ment of new types of functional solids.[
1,2]
The self-as-
sembly of metal-organic frameworks is highly influenced by
factors such as the geometric requirements of metal ions,
the ligand design,
III
anions may induce the self-assembly of Mn complexes,
[
3,4]
[7]
through a hydrogen-bonding net, to give 2D supramolec-
[
5,6]
the solvents used for crystallisation
[
10]
ular architectures
when the ligand has hydroxy func-
or the selection of the counteranions.[ Understanding the
role of these factors may extend our knowledge of the rel-
evant structural types and establishes proper synthetic stra-
tegies that lead to the desired species with predictable struc-
tures and properties.
8]
tional groups in adequate positions. We are now exploring
the use of weakly coordinating anions such as perchlorates,
III
[15–18]
nitrates, etc., to construct Mn polymer networks.
The ability of these anions for establishing hydrogen bonds
would allow new supramolecular architectures to be ob-
tained and would also lead to systems of interest for the
In recent times one of our research goals constitutes the
[
9–11]
study of supramolecular chemistry of manganese(III).
The coordination chemistry of this species has been exten-
[
19,20]
selective recognition between anions and receptors.
III
Herein we report a series of Mn –Schiff-base complexes
[
12,13]
sively studied
due to its rich redox behaviour, where
associated by perchlorate counteranions, using ligands with
manganese(III) complexes are the active sites of numerous
n
adequate OH groups. The selected Schiff-base ligands, H L
4
n
and H L (see Scheme 1), contain six and four potential
2
donor atoms, respectively. They have in common an inner
[
[
a] Dpto. de Química Inorgánica, Facultade de Química, Uni-
versidade de Santiago de Compostela,
compartment with two imine nitrogen atoms and two phe-
1
5782 Santiago de Compostela, Spain
n
nol oxygen atoms, but H L ligands have an extra couple of
4
b] Dpto. de Química Inorgánica, Facultade de Ciencias, Uni-
versidade de Santiago de Compostela,
n
outer phenol groups, while H L ligands present two outer
2
2
7002 Lugo, Spain
methoxy or ethoxy groups.
Eur. J. Inorg. Chem. 2007, 3789–3797
© 2007 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
3789

M. I. Fernández, M. Maneiro et al.
FULL PAPER
The IR spectra also show broad unsplit bands ca.
–1
–1
1
100 cm , together with bands at 630 cm , indicative of
the presence of the uncoordinated perchlorate anion.
The presence of a broad band at about 3400 cm–1 is
associated with coordinated and/or solvated water/meth-
anol molecules, but unfortunately it interferes with the ob-
[
22]
servation of uncoordinated hydroxy groups.
The ES mass spectra exhibit peaks relating to fragments
+
[
MnL] , which thus further corroborate coordination of the
ligand to the manganese ion. The appearance of minor
peaks in some complexes that could be assigned to the
+
[
Mn L ] dimeric entity (see Table 1) suggests their tendency
2
2
Scheme 1.
to dimerise, although this spectroscopic technique is not sen-
sitive enough to unambiguously detect either these dimers or
the coordinated water molecules in every case.
The room temperature magnetic moments of the com-
plexes are listed in Table 1. They exhibit values close to the
spin-only value of 4.9 BM, as expected for a high-spin mag-
Results and Discussion
Synthesis and Spectroscopic Studies
4
netically diluted d manganese(III) ion, indicating little or
The Schiff-base ligands were obtained in almost quanti- no antiferromagnetic interaction.
tative yield by the well-known experimental procedure, and
The electronic spectroscopic data recorded are very sim-
III
afterwards they were characterised by elemental analysis, ilar for all compounds 1–12, indicating that the Mn com-
electrospray, IR, H- and C NMR spectroscopy, as well plexes are behaving as high-spin octahedral d4 systems,
1
13
as the measurements of their melting points. Additionally, probably suffering a significant Jahn–Teller distortion
3
10
H L and H L gave crystals suitable for their characteri- which affects the spectra and complicates its interpretation.
2
4
sation by X-ray crystallography.
The manganese complexes were prepared following a (ε = 2600–3300 Lmol cm ) corresponds to the E
variation of the Boucher method reported by us pre- transition, and the peak appearing around 300 nm (ε =
The characteristic UV broad band obtained at 480–490 nm
–1
–1
5
5
ǟ T2g
g
[
21]
–1
–1
viously.
synthetic route, in high yield, are sparingly soluble in water base ligand Ǟ Mn LMCT band.
The manganese compounds obtained by this 21000–23000 Lmol cm ) can be attributed to the Schiff-
III
and common organic solvents, but are quite soluble in
Furthermore, the conductivity measurements in DMF
–1
MeOH, DMF and DMSO. Elemental analyses establish give Λ
their general formula as [MnL (H O/CH OH) ](ClO )- attributable to 1:1 electrolytes.
values of 90–60 µScm , indicating a behaviour
M
n
[23]
2
3
2
4
1
(
mH O) (m = 0, 1).
Paramagnetic H NMR spectroscopic studies of these
2
III
All these complexes show similar IR spectral features Mn complexes were undertaken using [D ]dmso as the
6
–1
(Table 1), exhibiting a strong band between 1621–1610 cm
solvent. The data are presented in Table 1. The interpret-
attributable to ν(C=Nimine), which is shifted 7–22 cm–1 ation of the data was based on previous findings for manga-
lower than that in the free ligand. An up-frequency shift of nese(III) complexes with related Schiff-base ligands.[
9,24]
–
1
the ν(COphenol) band to higher frequency (6–21 cm ) is also The spectra contain proton resonances that lie outside the
observed. These data suggest the coordination of the Schiff diamagnetic region (δ = 0–14 ppm) due to the well-known
base in its dianionic form to the metal through the inner isotropically shifting of the ligand protons for high-spin
III
phenol oxygen and the imine nitrogen atoms.
Mn complexes in an octahedral field. In this sense, the
1
Table 1. Magnetic moments, conductivity measurements, IR, H NMR and mass spectrometric data of the complexes.
ES [amu][a]
IR [cm–1
]
µ [BM]
Λ [µScm–1
]
1H NMR [ppm]
ν(O–H)
ν(C=N)[b]
N(C–O)[b]
ν(Cl–O)
H4
H5
1
[
[
[
[
[
[
[
[
[
Mn(H2
2
L )(H
2
O)
2
](ClO
4
)(H
2
O) (1)
353 (705)
382
410 (819)
368
396 (791)
424
382
409 (817)
438 (875)
395
424 (846)
451
3421
3419
3457
3424
3417
3418
3420
3413
3421
3416
3418
3429
1621 (1633)
1621 (1633)
1621 (1629)
1619 (1626)
1619 (1627)
1619 (1631)
1610 (1624)
1610 (1629)
1612 (1628)
1620 (1639)
1610 (1632)
1612 (1633)
1254 (1246)
1255 (1249)
1258 (1250)
1257 (1236)
1256 (1250)
1259 (1249)
1258 (1241)
1255 (1249)
1254 (1248)
1253 (1240)
1254 (1247)
1256 (1250)
1087; 636
1087; 636
1109; 623
1087; 636
1084; 636
1109; 624
1086; 625
1085; 625
1120; 625
1120; 620
1108; 624
1120; 625
4.9
4.9
5.0
5.0
5.0
5.0
5.0
5.0
5.0
5.0
4.9
4.9
75
66
70
75
60
88
75
62
88
62
63
89
–34.05
–27.37
–27.72
–34.15
–27.60
–27.64
–32.61
–27.80
–28.01
–30.27
–20.10
–20.72
–20.10
–19.20
–19.16
–21.99
–18.93
–18.82
–20.08
–18.64
–18.96
–20.08
–14.50
–16.75
Mn(L )(H
2
O)
O)
2
2
](ClO
](ClO
4
)(H
)(H
2
O) (2)
3
Mn(L )(H
2
4
2
O) (3)
4
Mn(H5
2
L )(H
2
O)(CH
3
OH)](ClO
4
) (4)
) (7)
Mn(L )(H
2
O)
O)
2
](ClO
](ClO
4
4
)(H
)(H
2
O) (5)
6
Mn(L )(H
2
2
2
O) (6)
7
Mn(H8
2
L )(H
2
O)(CH
3
OH)](ClO
4
Mn(L )(H
2
O)
2
](ClO
2
](ClO
4
) (8)
9
Mn(L )(H
2
O)
)(H
4
) (9)
10
[Mn(H1
[
[
2
L
2
O)(CH
3
OH)](ClO
)(H O) (11)
) (12)
4
) (10)
1
Mn(L )(H
2
O)
O)
2
](ClO
](ClO
4
2
Mn(L12)(H
2
2
4
+
2 2
L
]+. [b] Bands corresponding to the free ligands in parentheses.
[
a] Peaks corresponding to [MnL] , and, in parentheses, to [Mn
3790
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© 2007 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Eur. J. Inorg. Chem. 2007, 3789–3797

Self-Assembly of Dimeric MnIII–Schiff-Base Complexes
FULL PAPER
data obtained from these NMR spectroscopic studies serve
to corroborate the formation of the manganese(III) com-
plexes since two sets of upfield sharp peaks corresponding
to the H4 and H5 protons of the aromatic rings (Scheme 2)
are observed. Clearly the upfield signals (ranging from
–20.10 to –34.15 ppm) arise from H4 protons, while the
downfield resonances (–14.50 to –21.99 ppm) arise from H5
protons. Our experience shows that signals in ortho posi-
tions to donor atoms are not observable for these kinds of
1
complexes by paramagnetic H NMR spectroscopy. Since
H4 signals are discernible for all complexes, including 1, 4,
7
and 10, with external hydroxy groups in the aromatic
Figure 1. Molecular structure of H
bering scheme.
4
L10 showing the atomic num-
rings of the Schiff bases, the NMR spectra suggest no coor-
dination through these groups to the metal ion.
atoms form phenol groups, and they present longer C–O
distances [C5–O20 1.365(2) Å, C6–O21 1.347(2) Å, C18–
O23 1.361(2) Å], corresponding to the expected single
bonds.
The study of these distances reveals the transfer of one
proton from a hydroxy group of each molecule to the neigh-
bouring nitrogen atom N12. This process is favoured by the
[
25]
so-called “proton-sponge” effect,
which consists of the
increase in the basicity of the imine nitrogen atoms due to
the spatial nearness of their lone pairs. The instability of a
situation of proximity of these two lone pairs is then solved
by the attraction of one phenol hydrogen atom by one of
the nitrogen atoms. This leads to the formation of a rela-
Scheme 2.
+
tively strong [N–H···O] intramolecular bond [H22···O22
1
1
.75(2) Å, N12···O22 2.5914(19) Å and N12–H22···O22
45.2°]. Despite the symmetry of the compound, a second
3
10
Crystallographic Studies of Ligands H L and H L
2
4
proton transfer to the other imine nitrogen atom does not
1
0
Crystals of H L suitable for X-ray studies were ob- occur since it would mean a very unfavourable situation,
4
+
tained by slow evaporation of a methanol solution of the involving the formation of two neighbouring [N–H]
+
ligand. The crystal structure, with the numbering scheme, groups and preventing the [N–H···O] intramolecular hy-
is shown in Figure 1. Selected bond lengths and angles are drogen bond.
given in Table 2.
An additional intramolecular hydrogen bond exists be-
The crystal structure is made up of H L10 discrete mole- tween the N8 imine nitrogen atom and the neighbouring
4
cules. The C7–N8 and N12–C13 distances of 1.276(2) and phenol oxygen atom [H21···N8 1.55(3) Å, O21···N8
1.290(2) Å, respectively, are consistent with N=C double 2.5767(19) Å and O21–H21···N8 146.2°]. These intramolec-
bonding. One of the four oxygen atoms, O22, lacks a hydro- ular hydrogen bonds are typical of Schiff bases derived
[
26]
gen atom, appearing in the carbonyl form, which is corro- from salicylaldehydes.
Besides, intermolecular interac-
borated by the C19–O22 distance of 1.2928(18) Å, in ac- tions by hydrogen bonds can also be observed between the
cordance with a C=O double bond. The other three oxygen phenol oxygen atoms of neighbouring molecules.
3
10
Table 2. Selected bond lengths [Å] and angles [°] for the ligands H
L3
2
L and H
4
L .
H
2
H
4
L10
C10–N11
C1–O13
O7–C8
1.272(5)
1.344(4)
1.417(5)
N11–C12
C6–O7
1.461(5)
1.372(5)
C7–N8
N12–C13
C5–O20
1.276(2)
1.290(2)
1.365(2)
N8–C9
C11–N12
C6–O21
1.461(2)
1.459(2)
1.347(2)
C18–O23
1.361(2)
C19–O22
1.2928(18)
119.28(15)
112.87(14)
123.76(15)
119.23(17)
122.08(15)
120.28(14)
119.44(14)
N11–C10–C2
C12B–C12–N11
O13–C1–C6
O7–C6–C1
121.9(4)
110.5(5)
118.5(4)
113.9(4)
106.2(4)
C10–N11–C12
O13–C1–C2
C5–C6–O7
120.2(4)
121.8(4)
126.6(4)
117.4(4)
N8–C7–C1
N8–C9–C10
C13–N12–C11
O20–C5–C4
O21–C6–C5
O22–C19–C14
O23–C18–C17
121.93(15)
111.63(14)
124.97(15)
120.35(18)
118.15(15)
122.78(14)
119.47(16)
C7–N8–C9
N12–C11–C10
N12–C13–C14
O20–C5–C6
O21–C6–C1
O22–C19–C18
O23–C18–C19
C6–O7–C8
O7–C8–C9
Eur. J. Inorg. Chem. 2007, 3789–3797
© 2007 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjic.org
3791

M. I. Fernández, M. Maneiro et al.
FULL PAPER
According to this crystal structure study, the rather mined their molecular structures. Both crystal structures
planar conformation of the set N8–N12–O21–O22 suggests show similar features; thereby, they will be discussed to-
that this ligand should easily act as tetradentate donor in gether. An ORTEP view of 8 with the atomic numbering
the equatorial plane about an octahedral metal centre. scheme is shown in Figure 3. Experimental details are given
However, we cannot predict the role of the outer phenol in Table 5. Main bond lengths and angles are listed in
oxygen atoms of each aldehyde residue during complex- Table 3.
ation as they could coordinate, for instance, to the metal
centre by an axial position, but also their role could be lim-
ited to intermolecular hydrogen-bond interactions.
3
Slow evaporation of a methanol solution of ligand H L
2
gives crystals, suitable for X-ray diffraction studies, of
C H N O . The crystal structure is displayed in Figure 2
2
0
24
2
4
with the atom numbering scheme adopted. Selected bond
lengths and angles are in Table 2.
Figure 3. Molecular structure of 8 showing the atomic numbering
scheme.
3
Figure 2. Molecular structure of H
ing scheme.
2
L showing the atomic number-
Table 3. Selected bond lengths [Å] and angles [°] for complexes 2
and 8.
3
The crystal structure reveals that H L exists as discrete
2
molecules, and it is composed of two identical 3-methoxy- Complex 2
-hydroxybenzylimine moieties connected by the flexible Mn1–O13a
2
1.864(3)
1.866(3)
1.961(4)
4.8886(4)
Mn1–N4
Mn1–O1W
Mn1–O2W
1.968(4)
2.265(4)
2.314(4)
C12–C12B methylene chain (so-called spacer in supramo- Mn1–O43a
Mn1–N1
Mn···Mn
O13a–Mn1–O43a 92.61(13)
O43a–Mn1–N1
lecular chemistry), so we will only discuss one of them. The
C10–N11 distance of 1.272(5) Å is consistent with C=N
double bonding. Both imine groups are fully localised in
O13a–Mn1–N1
O13a–Mn1–N4
N1–Mn1–N4
O43a–Mn1–O1W 92.15(13)
N4–Mn1–O1W 88.43(14)
O43a–Mn1–O2W 87.93(17)
92.11(15)
174.84(15)
83.36(17)
175.26(16)
91.93(15)
the molecule. The angle of 120.2(4)° around the N11 atom O43a–Mn1–N4
2
O13a–Mn1–O1W 93.84(13)
N1–Mn1–O1W 87.17(14)
O13a–Mn1–O2W 88.20(15)
N1–Mn1–O2W 92.58(19)
confirms its sp character.
The disposition adopted by the free ligand in the solid
state is conditioned by two strong intramolecular hydrogen-
bond interactions which form two six-membered rings. O1W–Mn1–O2W 177.95(15)
N4–Mn1–O2W
89.52(17)
These interactions arise from the contact between the hy-
Complex 8
droxy and the imine groups. In this case and contrary to
Mn–O1
Mn–O2
Mn–N1
1.8482(15)
1.8529(16)
1.9648(19)
4.8896(4)
93.21(7)
92.07(7)
173.80(7)
89.04(6)
93.55(7)
93.81(6)
83.51(7)
176.97(6)
Mn–N2
Mn–O5
Mn–O6
1.9582(18)
2.2366(17)
2.3607(19)
1
0
the situation described for H L , both hydroxy oxygen
4
atoms retain their hydrogen atoms. As expected, the O13–
H13···N11 [H13···N11 1.59(7) Å, O13···N11 2.555(5) Å and Mn···Mn
O1–Mn–O2
O1–Mn–N2
O1–Mn–N1
N2–Mn–N1
O2–Mn–O5
N1–Mn–O5
O2–Mn–O6
N1–Mn–O6
174.10(7)
92.83(7)
81.83(8)
90.35(7)
91.17(7)
90.49(7)
87.70(7)
O13–H13···N11 154(6)°] hydrogen bonding establishes an
O2–Mn–N2
almost planar N11–C10–C2–C1–O13–H13 ring.
O2–Mn–N1
This kind of Schiff-base ligand, with a flexible spacer,
O1–Mn–O5
produces this type of “open” structure as we have pre- N2–Mn–O5
viously found in similar ligands.[
27,28]
These and other sim- O1–Mn–O6
N2–Mn–O6
O5–Mn–O6
ilar ligands present adequate conditions to be useful in the
synthesis of octahedral complexes, occupying the equatorial
positions around the metal centre.
n
+
The crystallographic analyses show [MnL (H O) ] mo-
2
2
nonuclear cationic complexes, where the geometry around
each manganese(III) ion can be described as distorted octa-
hedral. The structure of these cations comprises the planar
Crystallographic Studies of Complexes 2 and 8
2
Recrystallisation of [MnL (H O) ](ClO ) (2) and Schiff-base ligand tightly bound to the manganese(III) ion
2
2
4
8
[
MnL (H O) ](ClO ) (8) from methanol solutions by slow through the inner N O compartment by the N
and
2
2
4
2
2
imine
evaporation afforded brown crystals from which we deter- Ophenol atoms (Mn–Nimine bond lengths of 1.95–1.97 Å and
3792
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Eur. J. Inorg. Chem. 2007, 3789–3797

Self-Assembly of Dimeric MnIII–Schiff-Base Complexes
FULL PAPER
Mn–Ophenol of 1.84–1.87 Å are typical of such complexes rate ions which establish two pairs of hydrogen bonds to
[
9,10,29]
and corroborate the bisdeprotonation of the ligands),
two adjacent µ-aquo dimers. Each pair is directed from the
occupying the equatorial positions and giving rise to two perchlorate anions to the external capping water molecule
six-membered chelate rings (which are nearly planar) and of each dimeric building unit (see Figure 5). These multiple
an additional five-membered chelate ring. The coordination intermolecular interactions are extended into the solid to
sphere around each manganese centre is then completed by form infinite spirals generated by a screw axis along a. The
capping water molecules. The axial Mn–O distances (rang- 1D network of manganese dimers generates a kind of tun-
ing from 2.23 to 2.36 Å) are considerably longer than the nel along the c axis. Perchlorate anions are accommodated
equatorial Mn–O bond lengths quoted earlier, indicating in such cavities of the framework.
that the Jahn–Teller elongation expected for a high-spin d4
manganese(III) ion is present among these complexes. The
deviation from an ideal octahedral geometry is also re-
Table 4. Hydrogen-bonding scheme (distances and angles) involv-
ing perchlorate counterions for complexes 2 and 8.
vealed by the range of angles observed around the metal D–H···A [Å]
centre (from 81.83° to 93.84°), as well as by the interaxial
D–H [Å]
H···A [Å] D···A [Å] D–H···A [°]
Complex 2
2.47(8)
angle OW–Mn–OW of 177.95° for 2 and 176.97° for 8.
From the viewpoint of supramolecular chemistry, com-
plexes 2 and 8 exhibit a topology constructed by hydrogen
bonds, which help to stabilise the packing and induce the
assembly of the mononuclear cationic complexes.
The superstructure of the complexes involves associa-
tions through a combination of π-aryl interactions and hy-
drogen bonds between capping water and outer phenoxy
and axial water oxygen atoms of the neighbouring Schiff-
base ligand. This results in Mn···Mn distances of about
O2W–H12W···O2[a] 0.80(7)
O2W–H22W···O2
3.10(2)
2.71(2)
137(7)
157(7)
0.74(7)
2.01(7)
Complex 8
O6–H61–O10
O6–H62–O9[
1.024(16)
1.074(15)
1.981(19)
2.178(15)
2.886(2)
2.998(3)
146.(2)
131.3(15)
b]
[
a] Symmetry operations: 2 – x, 1 – y, 1 – z. [b] Symmetry opera-
tions: 1 – x, 1 – y, 1 – z.
4
.90 Å, which are short for monomeric compounds; these
2
+
types of [MnL(H O) ]
previously
systems have been reported by us
2
2 2
[
30,31]
as µ-aquo dimers (Figure 4). However, these
Mn···Mn distances are too long to establish intermetallic
interactions between neighbouring manganese ions, in ac-
cordance with the non-antiferromagnetic behaviour shown
by the magnetic studies.
Figure 5. Stick diagram for 8 showing the hydrogen bonding be-
8
2+
tween adjacent [MnL (H
2
O)
2
]
2
dimeric units through perchlorate
anions.
A comparison between the role of perchlorate and chlo-
ride counterions as multiple hydrogen-bond acceptors for
similar manganese(III) complexes derived from H L Schiff
4
bases may be established. We have previously reported how
each chloride ion could be involved in four O–H···Cl bonds,
connecting three neighbouring cationic complexes and as-
[
10]
sembling them to constitute a 2D network. In the present
work, we find each perchlorate anion is only able to form
two hydrogen bonds. This behaviour implies preference is
given to one direction and provokes a decrease in the di-
mensionality of the network.
Figure 4. Ball-and-stick diagram of the µ-aqua dimer formed for 2
through hydrogen bonds.
Redox Properties and Peroxidase Essays
Moreover, the µ-aquo dimers are interconnected by hy-
The electrochemical behaviour of some of the complexes
drogen bonding involving the perchlorate counterions. In (2, 3, 5, 7, 8 and 12) was studied by cyclic voltammetry. In
this way, pairs of neighbouring µ-aquo dimers are linked by all cases this technique exhibits a one-electron reduction-
two perchlorate anions. The hydrogen-bonding interactions oxidation peak system in the 0 to –0.1 V potential range.
involving perchlorate anions with their symmetry codes for The difference between the anodic and cathodic potentials
compounds 2 and 8 are given in Table 4. This hydrogen- indicates a redox reversible character. Moreover, these nega-
bonding scheme arises from the interactions of two perchlo- tive potentials belong to the range which would favour the
Eur. J. Inorg. Chem. 2007, 3789–3797
© 2007 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjic.org
3793

M. I. Fernández, M. Maneiro et al.
catalytic activity, as we have previously reported for other tra were recorded as KBr discs with a Bruker IFS-66V FTIR spec-
FULL PAPER
1
III
[31,32]
trophotometer and UV–Vis spectra with a Varian Cary IE. H-
Mn –Schiff-base systems.
1
3
and C NMR spectra were recorded with a Bruker WH 300 MHz
spectrometer using DMSO as the solvent and SiMe as an internal
reference. ES mass spectra were recorded with a Hewlett-Packard
LC-MSD Series 1100a spectrometer. Conductivities of 10–  solu-
tions in DMF were measured with a Crison Micro CM 2200 con-
ductivimeter. Room-temperature magnetic susceptibilities were
The peroxidase-like activity of the cited complexes was
followed by the oxidation of the diammonium salt of 2,2Ј-
azinobis(3-ethylbenzothiazoline)-6-sulfonic acid (ABTS) at
pH 6.8. The reaction of ABTS with H O in the presence
of the complexes generates ABTS , which can be clearly
identified by its characteristic absorption bands (415, 650,
4
3
2
2
·+
measured using
a Faraday balance MSB-MKI by Evans;
7
6
35 and 815 nm) and measured quantitatively at λ = HgCo(NCS) was employed as a susceptibility standard.
4
–
1
–1
50 nm since ε = 12000  cm has been determined. The
Electrochemical measurements were performed with an EG&G
PAR model 273 potentiostat, controlled by EG&G PAR model 270
software. A Metrohm model 6.1204.000 graphite disc coupled to a
Metrohm model 628–10 rotating electrolyte device was used as a
·+
rate of formation of ABTS ranges from 30–40% with re-
spect to the initial ABTS. This shows an important capacity
of hydrogen peroxide decomposition by the studied com-
plexes. The activity is comparable to that of a previous working electrode. A saturated calomel electrode was used as a ref-
series of Mn–Schiff-base complexes, reported by us, incor- erence, and a platinum wire was used as an auxiliary electrode. All
porating carboxylate ligands,[ but is much higher than an measurements were made with ca. 10 moldm solutions of the
31]
–3
–3
–
3
4 6
complexes in dimethylformamide using 0.2 moldm NBu PF as
a supporting electrode. Cyclic voltammetry measurements were
performed with a static graphite electrode.
earlier Mn–Schiff-base series with the chloride counter-
ion.[10] Recently, we have tried to establish a correlation be-
tween peroxidase activity and the structural motifs of the
[
31]
complexes. We have postulated what seems to be an easy Materials: 2,3-Dihydroxybenzaldehyde (Sigma–Aldrich), 3-meth-
oxy-2-hydroxybenzaldehyde (Fluka Chemika), 3-ethoxy-2-hydroxy-
approach to predict the capacity of H O decomposition
2
2
benzaldehyde (Fluka Chemika), diamines [1,2-diaminoethane, 1,2-
diamino-2-methylethane, 1,2-diamino-2,2-dimethylethane, 1,3-di-
amino-2,2-dimethylpropane] (Aldrich) and manganese(II) perchlo-
rate hexahydrate (Fluka) were used as received without further pu-
rification.
by these types of complexes as a finction of the tetragonal
elongation of the octahedral geometry in the crystal struc-
ture. An axial water molecule in this class of distorted geo-
metries constitutes a quite labile ligand, which would gener-
ate a vacant position in the coordination sphere to accom-
modate the substrate molecule.
In order to quantify the tetragonal elongation we have
employed the “rhombicity” of the structure as the ratio be-
tween their manganese–axial-oxygen distances and their
manganese–equatorial-oxygen distances. This correlation is
also valid for the data taken for complexes 2 and 8 of this
n
Preparation of the Ligands: The hexadentate Schiff bases, H
x
L ,
used in this study were prepared by condensation of the appropri-
ate diamine with 2,3-dihydroxybenzaldehyde, 3-methoxy-2-hy-
droxybenzaldehyde or 3-ethoxy-2-hydroxybenzaldehyde in meth-
[33,34]
anol.
They were isolated in virtually quantitative yield and
1
13
satisfactorily characterised by elemental analysis, H- and
C
NMR spectroscopy, ES mass spectroscopy and IR spectroscopy.
1
work. Their Mn–Ow/Mn–Oeq ratios of 1.24 and 1.27, This can be typified by the following preparation of H L .
4
respectively, are compatible with their peroxidase activity.
1
H
4
L : To a methanol solution (120 mL) of 2,3-dihydroxybenzal-
dehyde (4.00 g, 28.96 mmol) was added 1,2-diaminoethane
(0.97 mL, 14.48 mmol). This mixture was heated at reflux in a
round-bottomed flask fitted with a Dean Stark trap to remove the
water produced during the reaction. After heating for 3 h, the solu-
tion was concentrated to yield a yellow solid. The product was
collected by filtration, washed with diethyl ether and dried in air.
Conclusions
We can conclude that these types of manganese(III) com-
plexes, formed from Schiff bases with inner and outer O–X
(
X = H, CH , CH CH ) groups, constitute suitable building
3 2 3
units for establishing rich hydrogen-bonding networks. In
the present work, the selection of the proper spacer in the
16 16 2 4
C H N O (300.30): calcd. C 63.9, H 5.4, N 9.3; found C 63.3,
1
6
H 5.6, N 9.4. H NMR (300 MHz, [D ]DMSO): δ = 8.54 (s, 2 H),
2
+
13
Schiff-base ligand allows formation of [MnL]2 dimeric 6.65–6.85 (m, 6 H), 3.93 (s, 4 H) ppm. C NMR (75 MHz, [D6]-
units, which can be connected through perchlorate counter- DMSO): δ = 167.1 (C ), 151.0 (C ), 145.8 (C ), 118.1 (C ), 58.0
) ppm. ES-MS: m/z = 301.2. IR: ν˜ = ν(O–H) 3258, ν(C=N)
g
a
b
f
ions to form 1D chains. The lower dimensionality of the (C
h
–
1
1
633, ν(C–O) 1246 cm . M.p. 240 °C.
network with respect to the case of a chloride counterion
(2D Ǟ 1D) can be interpreted in terms of the lower sym-
2
2
H L : 3-Methoxy-2-hydroxybenzaldehyde (2.00 g, 13.15 mmol) and
metry of the perchlorate (tetrahedral) than that of the chlo- 1,2-diaminoethane (0.41 mL, 6.57 mmol). C H N O (328.37):
1
8
20
2
4
1
ride (spherical), involving a higher directionality of the net- calcd. C 65.8, H 6.2, N 8.5; found C 65.7, H 6.2, N 8.6. H NMR
work. The ability of these types of complexes to accommo- (300 MHz, [D ]DMSO): δ = 13.42 (br.), 8.56 (s, 2 H), 6.79–7.01 (t,
6
1
3
d, d, 6 H), 3.92 (s, 4 H), 3.76 (s, 6 H) ppm. C NMR (75 MHz,
date different anions in the vacancies of the framework be-
comes an interesting research field for selective recognition
between anions and receptors, beyond their worthwhile re-
dox behaviour.
[
(
1
D
6
]DMSO): δ = 167.7 (C
g a b h
), 152.3 (C ), 148.7 (C ), 59.0 (C ), 56.5
C
k
) ppm. ES-MS: m/z = 329.3. IR: ν˜ = ν(O–H) 3087, ν(C=N)
–
1
633, ν(C–O) 1249 cm . M.p. 165 °C.
3
H
2
L : 3-Ethoxy-2-hydroxybenzaldehyde (2.00 g, 12.04 mmol) and
1
,2-diaminoethane (0.40 mL, 6.02 mmol). C20
calcd. C 67.4, H 6.7, N 7.9; found C 66.9, H 6.8, N 7.1. H NMR
(300 MHz, [D ]DMSO): δ = 8.54 (s, 2 H), 6.72–6.99 (d, d, t, 6 H),
4.00 (q, 4 H), 3.97 (s, 4 H), 1.31 (t, 6 H) ppm. C NMR (75 MHz,
24 2 4
H N O (356.42):
Experimental Section
Physical Measurements: Elemental analyses were performed with a
1
6
1
3
Carlo Erba model 1108 CHNS-O elemental analyser. The IR spec-
3794
www.eurjic.org
© 2007 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Eur. J. Inorg. Chem. 2007, 3789–3797

Self-Assembly of Dimeric MnIII–Schiff-Base Complexes
FULL PAPER
[
(
D
6
]DMSO): δ = 167.7 (C
g
), 152.5 (C
a
), 147.8 (C
b
), 64.7 (C
k
), 59.1
(s, 2 H), 6.68–6.88 (t, d, d, 6 H), 3.51 (s, 4 H), 1.01 (s, 6 H) ppm.
1
3
C
h
), 15.4 (C ) ppm. ES-MS: m/z = 357.4. IR: ν˜ = ν(O–H) 3467,
l
C NMR (75 MHz, [D
6
]DMSO): δ = 166.0 (C
g
), 151.3 8 (C
a
),
–1
ν(C=N) 1629, ν(C–O) 1250 cm . M.p. 146 °C.
145.9 (C ), 118.0 (C ), 65.9 (C
m/z = 343. IR: ν˜ = ν(O–H) 3215, ν(C=N) 1639, ν(C–O) 1240 cm .
M.p. 180 °C.
b
f
k
), 35.7 (C ), 23.4 (C
i
j
) ppm. ES-MS:
–
1
4
H
4
L : 2,3-Dihydroxybenzaldehyde (4.00 g, 28.96 mmol) and 1,2-di-
amino-2-methylethane (1.23 mL, 14.48 mmol).
17 18 2 4
C H N O
1
1
(
314.34): calcd. C 64.9, H 5.8, N 8.9; found C 64.8, H 5.8, N 8.7.
H NMR (300 MHz, [D
H L : 3-Methoxy-2-hydroxybenzaldehyde (2.00 g, 13.15 mmol)
2
1
6
]DMSO): δ = 13.53 (br.), 9.00 (br.), 8.55
and 1,3-diamino-2,2-dimethylpropane (0.78 mL, 6.57 mmol).
(
s, 1 H), 8.52 (s, 1 H), 6.62–6.86 (m, 6 H), 3.81 (d, 2 H), 1.33 (d, 3
C H N O (370.45): calcd. C 68.1, H 7.0, N 7.6; found C 67.7,
2
1
26
2
4
13
1
H), 3.75–3.89 (m, 1 H) ppm. C NMR (75 MHz, [D
167.1/165.3 (C ), 151.2/150.5 (C ), 145.1/145.7 (C ), 118.0/118.2
), 63.6 (C ), 63.1 (C ), 19.9 (C ) ppm. ES-MS: m/z = 315. IR: ν˜
6
6
]DMSO): δ H 7.2, N 7.4. H NMR (300 MHz, [D ]DMSO): δ = 8.51 (s, 2 H),
=
g
a
b
6.76–7.03 (t, d, d, 6 H, ), 3.77 (s, 6 H), 3.47 (s, 4 H), 0.98 (s, 6 H)
1
3
(C
f
h
i
j
6 g a
ppm. C NMR (75 MHz, [D ]DMSO): δ = 167.3 (C ), 152.6 (C ),
–1
=
ν(O–H) 3240, ν(C=N) 1626, ν(C–O) 1236 cm . M.p. 164 °C.
b f h k i j
148.8 (C ), 124.0 (C ), 67.4 (C ), 56.6 (C ), 24.3 (C , C ) ppm. ES-
5
MS: m/z = 371.4. IR: ν˜ = ν(O–H) 3439, ν(C=N) 1632, ν(C–O) 1247
cm . M.p. 82 °C.
H
1
2
L : 3-Methoxy-2-hydroxybenzaldehyde (2.00 g, 13.15 mmol) and
–
1
,2-diamino-2-methylethane (0.56 mL, 6.57 mmol). C19
342.39): calcd. C 66.6, H 6.5, N 8.2; found C 66.5, H 6.8, N 8.2.
H NMR (300 MHz, [D
22 2 4
H N O
1
2
(
H L : 3-Ethoxy-2-hydroxybenzaldehyde (2.00 g, 12.04 mmol)
2
1
6
]DMSO): δ = 13.50 (br.), 8.54 (s, 1 H),
and 1,3-diamino-2,2-dimethylpropane (0.72 mL, 6.02 mmol).
8
.51 (s, 1 H), 6.73–7.01 (m, 6 H), 3.82 (m, 1 H), 3.80 (d, 2 H), 1.31 C H N O (398.50): calcd. C 69.3, H 7.5, N 7.0; found C 68.7,
23 30 2 4
s, 6 H) ppm. 13C NMR (75 MHz, [D
]DMSO): δ = 165.8/167.7 H 7.6, N 6.9. H NMR (300 MHz, [D ]DMSO): δ = 13.85 (br.),
1
(
(
6
6
C
g
), 151.3 (C
a
), 147.5 (C
b
), 64.8 (C
h
), 56.4/56.5 (C
k
), 64.0 (C
i
),
8.51 (s, 2 H), 6.74–7.02 (d, d, t, 6 H), 4.03 (q, 4 H), 3.48 (br.), 1.31
1
3
20.5 (C ) ppm. ES-MS: m/z = 343.1. IR: ν˜ = ν(O–H) 3440, ν(C=N)
1
j
(t, 6 H), 0.98 (s, 6 H) ppm. C NMR (75 MHz, [D ]DMSO): δ =
6
–1
627, ν(C–O) 1250 cm . M.p. 137 °C.
167.5 (C ), 152.7 (C ), 147.9 (C ), 118.4 (C ), 67.3 (C ), 64.7 (C ),
g
a
b
f
h
k
6
36.4 (C
i
), 24.3 (C
j
l
), 15.5 (C ) ppm. ES-MS: m/z = 398.7. IR: ν˜ =
H
1
2
L : 3-Ethoxy-2-hydroxybenzaldehyde (2.00 g, 12.04 mmol) and
–
1
ν(O–H) 3428, ν(C=N) 1633, ν(C–O) 1250 cm . M.p. 64 °C.
,2-diamino-2-methylethane (0.51 mL, 6.02 mmol). C21
27 2 4
H N O
(
371.45): calcd. C 67.9, H 7.3, N 7.5; found C 67.3, H 7.2, N 7.5.
Preparation of the Complexes: All the complexes were synthesised
by air oxidation of the solution made up from Mn(ClO ) ·6H O
1
6
H NMR (300 MHz, [D ]DMSO): δ = 13.5 (br.), 8.53 (s, 1 H), 8.50
4
2
2
s, 1 H), 6.71–6.98 (d, d, t, 6 H), 4.00 (q, 4 H), 3.96 (s, 2 H), 3.75 and the Schiff base.[ A typical preparation of these complexes is
21]
(
(
m, 1 H), 1.31 (d, 3 H), 1.29 (t, 6 H) ppm. 13C NMR (75 MHz, outlined.
[
6
D
6
]DMSO): δ = 165.8/167.8 (C
g
), 152.4 (C
a b k
), 147.7 (C ), 64.9 (C ),
2 2 3 4 4
L )(H O)(CH OH)](ClO ) (4): H
L4 (0.30 g, 0.95 mmol)
4
[
Mn(H
was dissolved in methanol (40 mL), and then a solution of NaOH
1.90 mmol, 4 ) in methanol (0.48 mL) was added. After stirring
for 10 min, a solution of Mn(ClO ) ·6H O (0.35 g, 0.95 mmol) in
4.0 (C ), 64.1 (C ), 20.6 (C ), 15.4 (C
i
h
j
l
) ppm. ES-MS: m/z = 371.4.
–1
IR: ν˜ = ν(O–H) 3523, ν(C=N) 1631, ν(C–O) 1249 cm . M.p. 91 °C.
(
7
H
4
L : 2,3-Dihydroxybenzaldehyde (4.00 g, 28.96 mmol) and 1,2-di-
4
2
2
amino-2,2-dimethylethane (1.52 mL, 14.48 mmol). C18
H
20
N
2
O
4
methanol (10 mL) was added, and the solution turned brown.
(
328.37): calcd. C 65.8, H 6.1, N 8.5; found C 65.8, H 6.3, N 8.5.
(Caution: Although no problems were encountered in this work,
1
H NMR (300 MHz, [D
6
]DMSO): δ = 13.61/14.17 (br.), 8.95 (br.), perchlorates are potentially explosive and should be handled in
8
.56 (s, 1 H), 8.52 (s, 1 H), 6.60–6.92 (m, 6 H), 3.79 (s, 2 H), 1.38
only small quantities and with care!) The progress of the reaction
(
(
(
s, 6 H) ppm. 13C NMR (75 MHz, [D
6
]DMSO): δ = 167.4/162.8 was followed by TLC for 3 d, and the mixture was then filtered.
C
C
g
), 152.2/150.9 (C
a
), 145.9/145.7 (C
b
), 118.1 (C
f
), 68.2 (C
h
), 59.4
The complex was obtained from the filtrate as a brown solid after
i
), 25.0 (C ) ppm. ES-MS: m/z = 329. IR: ν˜ = ν(O–H) 3227, crystallisation. It was isolated by filtration and washed with diethyl
j
–1
ν(C=N) 1645–1624, ν(C–O) 1241 cm . M.p. 183 °C.
18 22 2 10
ether and dried in air. Yield: 0.37 g (75%). C H ClMnN O
8
(516.77): calcd. C 41.8, H 4.3, N 5.4; found C 42.0, H 4.1, N 5.6.
H
2
L : 3-Methoxy-2-hydroxybenzaldehyde (2.00 g, 13.15 mmol)
1
1
and 1,2-diamino-2,2-dimethylethane (0.69 mL, 6.57 mmol). [Mn(H L )(H O) ](ClO )(H O) (1): H L (0.50 g, 1.66 mmol),
2
2
2
4
2
4
C
20
H
24
N
2
O
4
(356.42): calcd. C 67.6, H 6.9, N 7.8; found C 67.5,
4 2 2
Mn(ClO ) ·6H O (0.60 g, 1.66 mmol) and NaOH (0.83 mL,
1
H 6.9, N 7.8. H NMR (300 MHz, [D
.54 (s, 1 H), 8.51 (s, 1 H), 6.72–7.04 (m, 6 H), 3.77 (s, 2 H), 3.74
s, 6 H), 1.34 (s, 6 H) ppm. 13C NMR (75 MHz, [D
]DMSO): δ =
), 60.4 (C ), 56.3/
) ppm. ES-MS: m/z = 357.0. IR: ν˜ = ν(O–H)
6
]DMSO): δ = 13.57 (br.), 3.32 mmol). Yield: 0.76 g (90%). C H ClMnN O (506.73):
16 20 2 11
8
(
1
5
3
calcd. C 37.9, H 4.0, N 5.5; found C 38.0, H 3.9, N 5.8.
6
2
H
2
L2 (0.33 g, 1.00 mmol),
[
Mn(L )(H
2
O)
·6H
.00 mmol). Yield: 0.35 g (65%). C18
2
](ClO
(0.36 g, 1.00 mmol) and NaOH (0.50 mL,
24ClMnN 11 (534.78):
4
)(H
2
O) (2):
63.4/167.9 (C
g
), 152.9 (C
a
), 148.7 (C
b
), 69.4 (C
i
h
Mn(ClO
4
)
2
2
O
6.4 (C ), 25.7 (C
k
j
2
H
2
O
–1
333, ν(C=N) 1629, ν(C–O) 1249 cm . M.p. 183 °C.
calcd. C 40.4, H 4.5, N 5.2; found C 40.1, H 4.3, N 5.2. Complex 2
was recrystallised from methanol solution, affording brown crystals
9
H
2
L : 3-Ethoxy-2-hydroxybenzaldehyde (2.00 g, 12.04 mmol)
and 1,2-diamino-2,2-dimethylethane (0.63 mL, 6.02 mmol). adequate for X-ray diffraction studies.
(384.47): calcd. C 68.7, H 7.3, N 7.3; found C 67.9,
22 28 2 4
C H N O
3
H
2
L3 (0.20 g, 0.56 mmol),
[
Mn(L )(H
Mn(ClO
.12 mmol). Yield: 0.10 g (32%). C20
2
O)
2
](ClO
(0.20 g, 0.56 mmol) and NaOH (0.28 mL,
28ClMnN 11 (562.84):
4
)(H
2
O) (3):
1
H 7.6, N 7.5. H NMR (300 MHz, [D
8
1
6
]DMSO): δ = 8.53 (s, 1 H),
.50 (s, 1 H), 6.69–7.00 (d, d, t, 6 H), 4.00 (q, 4 H), 3.96 (s, 2 H),
.34 (s, 6 H), 1.30 (t, 6 H) ppm. 13C NMR (75 MHz, [D
]DMSO):
), 152.4 (C ), 147.8 (C ), 69.4 (C ), 64.7/64.8
), 25.7 (C ), 15.4 (C ) ppm. ES-MS: m/z = 385.4. IR:
ν˜ = ν(O–H) 3433, ν(C=N) 1628, ν(C–O) 1248 cm . M.p. 88 °C.
4
)
2
·6H
2
O
1
H
2
O
6
calcd. C 42.7, H 5.0, N 5.0; found C 42.0, H 4.9, N 4.8.
δ = 167.9/168.0 (C
), 60.3 (C
g
a
b
i
5
H
2
L5 (0.39 g, 1.00 mmol),
(
C
k
h
j
l
[Mn(L )(H
2
O)
·6H
.00 mmol). Yield: 0.35 g (65%). C19
2
](ClO
(0.36 g, 1.00 mmol) and NaOH (0.50 mL,
26ClMnN 11 (548.81):
4
)(H
2
O) (5):
–1
Mn(ClO
2
4
)
2
2
O
H
2
O
10
H
4
L : 2,3-Dihydroxybenzaldehyde (2.00 g, 14.48 mmol) and 1,3-
diamino-2,2-dimethylpropane (0.86 mL, 7.24 mmol). C19
342.39): calcd. C 66.7, H 6.5, N 8.2; found C 66.9, H 6.6, N 8.1.
calcd. C 41.6, H 4.8, N 5.1; found C 41.4, H 4.6, N 5.1.
22 2 4
H N O
6
H
2
L6 (0.20 g, 0.54 mmol),
(
[Mn(L )(H
2
O)
2
](ClO
4
)(H
2
O) (6):
1
H NMR (300 MHz, [D
6
]DMSO): δ = 13.89 (br.), 9.02 (br.), 8.52
Mn(ClO
4
)
2
·6H
2
O (0.19 g, 0.54 mmol) and NaOH (0.27 mL,
Eur. J. Inorg. Chem. 2007, 3789–3797
© 2007 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjic.org
3795

M. I. Fernández, M. Maneiro et al.
FULL PAPER
3
10
Table 5. Crystal data and structure refinement for H
2
L , H
4
L , 2 and 8.
L10
H
2
L3
H
4
2
8
Empirical formula
Formula weight
Temperature [K]
Wavelength [Å]
Crystal system
Space group
a [Å]
b [Å]
c [Å]
α [°]
β [°]
C
356.41
293(2)
1.54180
monoclinic
C2/c
22.581(5)
7.0115(9)
12.4645(19)
90.00
108.336(15)
90.00
1873.3(6)
4
1.264
20
H
24
N
2
O
4
C
342.39
293(2)
0.71069
monoclinic
P2 /c
6.7030(4)
13.8580(6)
19.1350(10)
90.00
91.687(4)
90.00
1776.68(16)
4
1.280
0.090
19
H
22
N
2
O
4
C
516.77
293(2)
0.71073
orthorhombic
Pbca
13.990(5)
13.349(5)
22.745(5)
90.000(5)
90.000(5)
90.000(5)
4248(2)
8
18
H
22ClMnN
2
O
10
20 2 10
C H26ClMnN O
544.82
293(2)
0.71073
monoclinic
1
1
P2 /c
13.4577(19)
13.4504(17)
14.375(2)
90.00
116.975(19)
90.00
2319.0(6)
4
1.560
γ [°]
Volume [Å ]
3
Z
D
–
3
c
[gcm ]
1.616
0.807
2128
–
1
Absorption coefficient [mm ]
F(000)
0.721
760
0.743
1128
728
Crystal size [mm]
Theta range for data collection [°]
Reflections collected
0.40ϫ0.10ϫ0.04
4.12 to 65.26
1694
0.36ϫ0.28ϫ0.24
1.81 to 26.33
3934
0.19ϫ0.18ϫ0.03
1.79 to 21.99
25121
0.45ϫ0.40ϫ0.10
1.70 to 24.97
4235
Independent reflections
Data/restraints/parameters
Goodness-of-fit on F
1606 [R(int) = 0.0922]
1606/0/124
0.891
3618 [R(int) = 0.0134]
3618/0/253
1.032
2602 [R(int) = 0.0876]
2602/356/337
1.054
4072 [R(int) = 0.0160]
4072/0/253
1.005
2
Final R indices [I Ͼ 2σ(I)]
R
wR
R
wR
1
= 0.0599
= 0.1353
= 0.1993
= 0.1899
R
wR
R
wR
1
= 0.0456
= 0.1371
= 0.0605
= 0.1477
R
wR
R
wR
1
= 0.0444
= 0.1023
= 0.0793
= 0.1146
R
wR
2
R
1
wR
2
1
= 0.0260
= 0.0539
= 0.0392
= 0.0642
2
2
2
R indices (all data)
1
1
1
2
2
2
1.08 mmol). Yield: 0.21 g (68%). C21
H31ClMnN
2
O11 (577.87):
(10 µL, 10–3 , 10–8 mol) were added to water (3 mL). The oxi-
calcd. C 43.7, H 5.2, N 4.9; found C 44.0, H 5.0, N 4.7.
dation of ABTS started immediately after addition of an aqueous
–
4
7
L7 (0.30 g, 0.91 mmol),
3 4 4
OH)](ClO ) (7): H
solution of H
X-ray Crystallographic Studies: Crystals of H
suitable for X-ray diffraction studies were obtained by slow evapo-
2 2
O (50 µL, 10 , 5ϫ10 mol).
[
Mn(H
Mn(ClO
.82 mmol). Yield: 0.29 g (60%). C19
calcd. C 43.0, H 4.6, N 5.3; found C 42.7, H 4.3, N 5.3.
2
L )(H
2
O)(CH
·6H (0.33 g, 0.91 mmol) and NaOH (0.46 mL,
24ClMnN 10 (530.79):
3
10
)
2
2
O
2 4
L , H L , 2 and 8
4
1
H
2
O
1
0
ration of methanol solutions of the cited solids. Data for H
were collected with a Smart CCD-1000 Bruker diffractometer
employing graphite-monochromated Mo-K (λ = 0.71073 Å) radia-
tion. Data for 8 were collected with a Nonius FR591-kappa
CCD2000 diffractometer using graphite-monochromated Mo-K (λ
L were collected with a Non-
ius Mach3 diffractometer employing graphite-monochromated Cu-
(λ = 1.54180 Å) radiation. The structures were solved by direct
4
L and
2
8
8
[
Mn(L )(H
H
2
2
O)
O (0.36 g, 1.00 mmol) and NaOH (0.50 mL, 2.00 mmol). Yield:
.35 g (65%). C20 26ClMnN 10 (544.82): calcd. C 44.1, H 4.8, N
.1; found C 43.8, H 4.7, N 5.0. Single brown crystals, useful for
2 4 2 4 2
](ClO ) (8): H L (0.36 g, 1.00 mmol), Mn(ClO ) ·
α
6
0
5
H
2
O
α
3
=
0.71073 Å) radiation. Data for H
2
X-ray diffraction studies, were obtained from slow evaporation of
a methanol solution of complex 8.
K
α
9
9
[35]
[
Mn(L )(H
2
O)
O (0.18 g, 0.52 mmol) and NaOH (0.26 mL, 1.04 mmol). Yield:
.25 g (83%). C22 30ClMnN 10 (572.87): calcd. C 46.1, H 5.2, N
.9; found C 46.4, H 5.1, N 4.6.
2
](ClO
4
) (9): H
2
L (0.20 g, 0.52 mmol), Mn(ClO
4
)
2
·
methods
and finally refined by full-matrix least-squares based
2
6
0
4
H
2
on F . An empirical absorption correction was applied using SAD-
ABS.[ All non-hydrogen atoms were anisotropically refined, and
all hydrogen atoms were included in the model at geometrically
36]
H
2
O
1
0
L10
calculated positions. Detailed data collection and refinement of the
[
0
(
(
Mn(H
2
L )(H
2
O)(CH
3
OH)](ClO
·6H
4
)
(10):
H
4
(0.30 g,
3
compounds are summarised in Table 5. CCDC-636345 (H
2
L ),
.88 mmol), Mn(ClO
4
)
2
2
O (0.32 g, 0.88 mmol) and NaOH
26ClMnN
532.81): calcd. C 44.1, H 4.8, N 5.1; found C 44.3, H 4.6, N 5.0.
1
0
-
4
636346 (H L ), -636347 (2) and -636348 (8) contain the supple-
0.44 mL, 1.76 mmol). Yield: 0.34 g (70%). C19
H
2 10
O
mentary crystallographic 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.
1
1
4 2 2
)(H O) (11): H
L11 (0.20 g, 0.68 mmol),
[
Mn(L )(H
Mn(ClO ·6H
.35 mmol). Yield: 0.10 g (30%). C21
calcd. C 43.7, H 5.2, N 4.9; found C 43.3, H 5.0, N 4.7.
2
O)
2
](ClO
(0.20 g, 0.68 mmol) and NaOH (0.34 mL,
30ClMnN 11 (576.86):
4
)
2
2
O
1
H
2
O
Acknowledgments
1
2
2 4 2 4 2
](ClO )(12): H ) ·
L12 (0.20 g, 0.50 mmol), Mn(ClO
[
Mn(L )(H
2
O)
O (0.18 g, 0.50 mmol) and NaOH (0.25 mL, 1.00 mmol). Yield:
.22 g (75%). C23 32ClMnN 10 (586.90): calcd. C 47.1, H 5.5, N
.8; found C 48.0, H 5.4, N 4.6.
We thank Ministerio de Ciencia y Tecnología of Spain (BQU2003-
6
0
4
H
2
00167) and Xunta de Galicia (PGIDIT06TAM26201PR) for finan-
H
2
O
cial support.
Peroxidase Probes: Oxidation of 2,2Ј-azinobis(3-ethylbenzothi-
azoline-6-sulfonic acid) (ABTS) with H in the presence of the
complexes was tested. An aqueous solution of ABTS (50 µL,
[
1] J. M. Lehn, Supramolecular Chemistry: Concepts and Perspec-
2
O
2
tives, Wiley-VCH, Weinheim, Germany, 1995.
[2] S. Leininger, B. Olenyuk, P. J. Stang, Chem. Rev. 2000, 100,
853–908.
0
.009 , 4.5ϫ10–7 mol) and a methanol solution of the complex
3796
www.eurjic.org
© 2007 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Eur. J. Inorg. Chem. 2007, 3789–3797

Self-Assembly of Dimeric MnIII–Schiff-Base Complexes
FULL PAPER
[
[
3] E. C. Constable, Chem. Commun. 1997, 1073–1080.
[21] M. R. Bermejo, A. Castineiras, J. C. Garcia-Monteagudo, M.
Rey, A. Sousa, M. Watkinson, C. A. McAuliffe, R. G. Pritch-
ard, R. L. Beddoes, J. Chem. Soc. Dalton Trans. 1996, 2935–
4] G. F. Swiegers, T. J. Malafetse, Coord. Chem. Rev. 2002, 225,
91–121.
2944.
[
[
[
5] D. L. Caulder, K. N. Raymond, Acc. Chem. Res. 1999, 32, 975–
[
22] W. Mazurek, A. M. Bond, M. J. O’Connor, A. G. Wedd, Inorg.
982.
Chem. 1986, 25, 906–915.
6] M. R. Bermejo, A. M. González-Noya, R. Pedrido, M. J. Ro-
mero, M. Vázquez, Angew. Chem. Int. Ed. 2005, 44, 4182–4187.
7] M. R. Bermejo, M. Fondo, A. M. Gonzalez, O. L. Hoyos, A.
Sousa, C. A. McAuliffe, W. Hussain, R. Pritchard, V. M. Novo-
torsev, J. Chem. Soc. Dalton Trans. 1999, 2211–2218.
8] L.-P. Zhang, M. Du, W.-J. Lu, T. C. W. Mak, Inorg. Chem.
Commun. 2005, 8, 623–625.
9] M. R. Bermejo, A. M. González-Noya, V. Abad, M. I.
Fernández, M. Maneiro, R. Pedrido, M. Vázquez, Eur. J. Inorg.
Chem. 2004, 3696–3705.
[
[
23] W. I. Geary, Coord. Chem. Rev. 1971, 7, 81–122.
24] J. Bonadies, M. Maroney, V. L. Pecoraro, Inorg. Chem. 1989,
2
8, 2044–2051.
25] A. L. Llamas-Saiz, C. Foces-Foces, J. Elguero, J. Mol. Struct.
994, 328, 297–323.
26] A. Filarowski, A. Koll, A. Karpfen, P. Wolschann, Chem. Phys.
004, 297, 323–332.
[
[
[
1
[
[
2
27] M. Vázquez, M. R. Bermejo, M. Fondo, A. M. González, J.
Mahía, L. Sorace, D. Gatteschi, Eur. J. Inorg. Chem. 2001,
1863–1868.
[
10] M. R. Bermejo, M. I. Fernández, A. M. González-Noya, M.
Maneiro, R. Pedrido, M. J. Rodriguez, M. Vázquez, Eur. J. In-
org. Chem. 2004, 2769–2774.
[
28] M. Vázquez, M. R. Bermejo, M. Fondo, A. García-Deibe,
A. M. González, R. Pedrido, Eur. J. Inorg. Chem. 2002, 465–
472.
[
11] J.-P. D. Costes, B. Donnadieu, M. J. Rodríguez, M. I.
[29] M. Watkinson, M. Fondo, M. R. Bermejo, A. Sousa, C. A.
McAuliffe, R. G. Pritchard, N. Jaiboon, N. Aurangzeb, M.
Naeem, J. Chem. Soc. Dalton Trans. 1999, 31–41.
[30] C. A. McAuliffe, R. G. Pritchard, A. García-Deibe, A. Sousa,
M. R. Bermejo, Acta Crystallogr., Sect. C 1992, 48, 364–366.
[31] M. R. Bermejo, M. I. Fernández, A. M. González-Noya, M.
Maneiro, R. Pedrido, M. J. Rodríguez, J. C. García-Montea-
gudo, B. Donnadieu, J. Inorg. Biochem. 2006, 100, 1470–1478.
Fernández, A. Bousseksou, J.-P. Tuchagues, Inorg. Chem. 2004,
4
3, 2736–2744.
12] V. L. Pecoraro, W.-Y. Hsieh, Met. Ions Biol. Syst. 2000, 37,
29–504.
[
[
4
13] M. Maneiro, W. F. Ruettinger, E. Bourles, G. L. McLendon,
G. C. Dismukes, Proc. Natl. Acad. Sci. USA 2003, 100, 3707–
3712.
[
[
[
14] J. D. Crowley, D. A. Traynor, D. C. Weatherburn, Met. Ions [32] M. Maneiro, M. R. Bermejo, M. I. Fernández, E. Gómez-
Biol. Syst. 2000, 37, 209–278.
Fórneas, A. M. González-Noya, A. M. Tyryshkin, New J.
Chem. 2003, 27, 727–733.
[33] U. Casellato, P. Guerriero, S. Tamburini, P. A. Vigato, C. Be-
nelli, Inorg. Chim. Acta 1993, 207, 39–58.
[34] J. Sanmartín, M. R. Bermejo, A. M. García-Deibe, I. M. Rivas,
A. R. Fernández, J. Chem. Soc. Dalton Trans. 2000, 4174–4181.
[35] G. M. Sheldrick, SHELX-97 (SHELXS 97 and SHELXL 97),
Programs for Crystal Structure Analyses, University of
Göttingen, Germany, 1998.
15] P. S. Subramanian, E. Suresh, P. Dastidar, Polyhedron 2004, 23,
2515–2522.
16] I. Yoon, J. Seo, J.-E. Lee, M. R. Song, S. Y. Lee, K. S. Choi,
O.-S. Jung, K.-M. Park, S. S. Lee, Dalton Trans. 2005, 2352–
2354.
[
17] L. Yi, X. Yang, T. Lu, P. Cheng, Cryst. Growth Des. 2005, 5,
1215–1219.
[
18] S. H. Rahaman, H. Chowdhury, D. Bose, G. Mostafa, H.-K.
Fun, B. K. Ghosh, Inorg. Chem. Commun. 2005, 8, 1041–1044.
19] P. D. Beer, Acc. Chem. Res. 1998, 31, 71–80.
[36] G. M. Sheldrick, SADABS, Program for Scaling and Correction
of Area Detector Data, University of Göttingen, Germany,
1996.
[
[
20] M. Vázquez, L. Fabbrizzi, A. Taglietti, R. M. Pedrido, A. M.
González-Noya, M. R. Bermejo, Angew. Chem. Int. Ed. 2004,
Received: February 12, 2007
Published Online: June 29, 2007
43, 1962–1965.
Eur. J. Inorg. Chem. 2007, 3789–3797
© 2007 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjic.org
3797