A series of [Mn6] complexes with terminal functional groups

Article abstract of DOI:10.1002/zaac.201100524

A series of [Mn₆O₂(R¹OH) ₄(sao)₆(R²COO)₂] complexes with terminal functional groups (1: R¹ = CH₃, R² = HO-C₆H₄, 2: R¹ = C₂H₅, R² = H₂N-C₆H₄, 3: R¹ = CH₃, R² = Cl-C₆H₄, 4: R¹ = CH₃, R² = CH₃S-C₆H₄, 5: R¹ = CH₃, R² = I-C₆H₄, 6: R¹ = CH₃, R² = pymSCH₂, 7: R ¹ = CH₃, R² = ortho-pyr-SCH₃, 8: R¹ = C₂H₅, R² = (CH ₃)₃OOCNHCH₂C₆H₄; sao = doubly deprotonated salicylaldoxime ligand, pym = pyrimidyl, pyr = pyridyl) have been obtained in a reaction of a ligand R²C₆H ₄COOH, salicylaldoxime, manganese(II) perchlorate and [NEt ₄](OH) in methanol or a 1:1 mixture of ethanol and dichloromethane. In this report, structural aspects as well as preliminary studies of magnetic and thermal properties are presented. Compounds 1, 3, 6, 8 exhibit an antiferromagnetic coupling of the Mn²⁺ ions, whereas 4 and 7 show ferromagnetic interactions. The title compounds may act as starting materials for further derivatization addressing the functional groups. Copyright

Full text of DOI:10.1002/zaac.201100524

ARTICLE
DOI: 10.1002/zaac.201100524
A Series of [Mn6] Complexes with Terminal Functional Groups
Małgorzata Hołyn´ska*[a] and Stefanie Dehnen*[a]
Keywords: Polynuclear complexes; Manganese; Salicylaldoxime; X-ray diffraction
Abstract. A series of [Mn6O2(R1OH)4(sao)6(R2COO)2] complexes [NEt4](OH) in methanol or a 1:1 mixture of ethanol and dichlorometh-
with terminal functional groups (1: R1 = CH3, R2 = HO-C6H4, 2: R1 =
ane. In this report, structural aspects as well as preliminary studies of
C2H5, R2 = H2N-C6H4, 3: R1 = CH3, R2 = Cl-C6H4, 4: R1 = CH3, R2 magnetic and thermal properties are presented. Compounds 1, 3, 6, 8
= CH3S-C6H4, 5: R1 = CH3, R2 = I-C6H4, 6: R1 = CH3, R2 = pymSCH2, exhibit an antiferromagnetic coupling of the Mn2+ ions, whereas 4 and
7: R1 = CH3, R2 = ortho-pyr-SCH3, 8: R1 = C2H5, R2 = (CH3) 7 show ferromagnetic interactions. The title compounds may act as
3OOCNHCH2C6H4; sao = doubly deprotonated salicylaldoxime ligand,
starting materials for further derivatization addressing the functional
pym = pyrimidyl, pyr = pyridyl) have been obtained in a reaction of a groups.
ligand R2C6H4COOH, salicylaldoxime, manganese(II) perchlorate and
R2 = H2N-C6H4, 3: R1 = CH3, R2 = Cl-C6H4, 4: R1 = CH3,
Introduction
R2 = CH3S-C6H4, 5: R1 = CH3, R2 = I-C6H4, 6: R1 = CH3,
R2 = pym-SCH2, 7: R1 = CH3, R2 = ortho-pyr-SCH3, 8:
R1 = C2H5, R2 = (CH3)3OOCNHCH2C6H4; sao = doubly de-
protonated salicylaldoxime, pym = pyrimidyl, pyr = pyridyl).
Compounds 1–8 contain sterically well available functional
groups (Scheme 1).
Polynuclear mixed-valent manganese complexes represent
an established part of materials science. Since the discovery of
the first polynuclear mixed-valence [Mn12] complex[1] exhibit-
ing the so-called “single molecule magnet (SMM) behavior”[2]
attempts have been made to modify the structure of this com-
plex or to create new structural types. An important part of
motivation for exploring the chemistry of the ligand part of
functionalized SMMs involves the perspective of to attach
these molecules to functionalized surfaces via organic reac-
tions.[3]
New approaches aiming at their assembling into novel
frameworks are also worth pursuing, representing part of a
“bottom-up“ approach.[4] One possible way into the desired
direction would be the functionalization of large metal clusters,
which is an uncommon approach in synthetic chemistry, re-
cently utilized for chalcogenidometallates.[5] It has been
shown, that the synthetic principle of introducing functional
groups to larger clusters, is of crucial importance for the design
of new materials, in particular bearing applications as labeling
and imaging agents for biological systems.[6a] The principle
has been especially applied to polyoxoanions of vanadium,
molybdenum and tungsten so far.[6] In this paper we communi-
cate a series of functionalized complexes with a known
[Mn6O2] core[7] that was recently published as a complex com-
prising a record anisotropy barrier for a SMM: [Mn6O2(R1OH)4-
(sao)6(R2COO)2] (1: R1 = CH3, R2 = HO-C6H4, 2: R1 = C2H5,
Scheme 1. Formulae of acids that served as ligand sources for the
ligands bearing functional groups in 1–8.
* Prof. Dr. S. Dehnen, Dr. M. Hołyn´ska
E-Mail: dehnen@chemie.uni-marburg.de
[a] Fachbereich Chemie
Results and Discussion
Wissenschaftliches Zentrum für Materialwissenschaften
Philipps-Universität Marburg
Synthesis
Hans-Meerwein-Strasse
35043 Marburg, Germany
The formation of the 1–8 took place according to equation
Supporting information for this article is available on the WWW
under http://dx.doi.org/10.1002/zaac.201100524 or from the author. (1):
Z. Anorg. Allg. Chem. 2012, 638, (5), 763–769
© 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
763

M. Hołyn´ska, S. Dehnen
ARTICLE
bonds involving solvent water molecules. Compound 2 (Fig-
ure 1) contains the 4-aminobenzoate ligand. Recently, Kozoni
et al.[9] reported a complex analogous to 2 with 2-hydroxyetha-
none oxime instead of salicylaldoxime ligands. Here, the same
molecules were also observed with two water ligands instead
of two methanol ligands, resulting in a novel twist conforma-
tion of the complex. In 2, only one kind of complex is present
that adopts the “untwisted” form – as all compounds reported
herein. Hydrogen-bonded layers are observed parallel to (011)
(Figure S1). Solvent ethanol molecules link the complexes to
stabilize the layers. The 4-chlorobenzoate ligand attached to
the complex in compound 3 (Figure 1) was previously used for
the stabilization of other polynuclear, mixed-valent manganese
complexes structures (see for instance[10]). In 3, the disordered
molecules and solvent molecules are linked via hydrogen
bonds to form chains parallel to the crystallographic a axis
(Figure S1). The ordered molecules do not participate in this
interaction, but they are also hydrogen-bonded to disordered
solvent molecules. Compound 4 (Figure 1) represents the sec-
ond known polynuclear manganese complex with the ligand 4-
(methylthio)benzoate. The reported SMM [Mn12] complex was
deposited on gold surfaces.[3] In compound 4, methanol sol-
vent molecules are hydrogen-bonded to the complex mole-
cules. The complex molecules are packed in columns parallel
to the crystallographic b axis (Figure S1). They show only
weak C–H···π and C–H···O interactions and are thus not in-
volved in any supramolecular aggregation. Compound 5 (Fig-
ure 1) is the first manganese complex comprising a 4-iodoben-
zoate ligand. Although 3 and 5 are highly related and triclinic,
they are not isomorphous. Complex molecules in 5 form col-
umns along [011] (Figure S1), in which adjacent molecules
and disordered methanol molecules are involved in a hydrogen
bonding network. The (2-pyrimidylthio)acetate ligand in 6
(Figure 1) has also not been used in manganese chemistry so
far, but is rather known from tin(IV) complexes (see for in-
stance[11a]). Three further examples include a lanthanum com-
plex,[11b] a silver complex[11c] and a copper complex.[11d] Two
kinds of hydrogen-bonded chains extending along [010] may
be distinguished in 6. One shows interactions via O–H···N hy-
drogen bridges with methanol O141 atoms as donor and pyri-
midyl N261 atoms at –x, –y + 2, –z as acceptors (Table S3).
The second is generated by O–H···O hydrogen bonds with
methanol ligands as both donors and acceptors, as well as sol-
vent methanol molecules as donors to form ring motifs.
(1: R1 = CH3, R2 = HO-C6H4, 2: R1 = C2H5, R2 = H2N-C6H4,
3: R1 = CH3, R2 = Cl-C6H4, 4: R1 = CH3, R2 = CH3S-C6H4,
5: R1 = CH3, R2 = I-C6H4, 6: R1 = CH3, R2 = pym-SCH2, 7:
R1 = CH3, R2 = ortho-pyr-SCH3, 8: R1 = C2H5, R2 = (CH3)3-
OOCNHCH2–C6H4; sao = doubly deprotonated salicylaldox-
ime ligand, pym = pyrimidyl, pyr = pyridyl).
Crystal Structures
Compounds 1–8 (Figure 1) contain a known [Mn6] core,[7]
comprising two [Mn3O] triangles with three MnIII atoms and
two μ3-bridging oxido ligands, which are linked by two further
oxygen atoms from oxime groups. The two subunits are related
by a crystallographic symmetry center (Figure 1). Each [Mn3]
unit also contains three doubly deprotonated salicylaldoxime
ligands that surround the three MnIII atoms as a ring of chelat-
ing ligands to form a [MnNO]3 nine-membered ring. One MnIII
atom per subunit (Mn1) is pentacoordinate. The second MnIII
atom (Mn2) is hexacoordinate as a consequence of additional
coordination by the bridging oxygen atom from the opposite
subunit. The remaining MnIII atom (Mn3) is hexacoordinate
with two solvent molecules (methanol/ethanol) coordinating
trans to each other. The R2-COO ligand coordinates biden-
tately to the Mn2 and Mn1 (or symmetry equivalent) atoms of
each triangular [Mn3] unit, in a symmetric μ2,η2-coordination
mode. The μ3-O ligand within the triangular [Mn3] units is
shifted from the [Mn3] plane by a minimum value of
0.128(3) Å (in 8) to a maximum value of 0.232(5) Å (in 1).
(Table S3). All complex molecules in 1–8 differ slightly in the
distortion of the [Mn6(sao)6] core, and compounds 2, 3, 6 and
7 additionally contain two symmetry-independent molecules
that differ in angular distortion of the [Mn3] units and the de-
gree of disorder (Table S1).
In all structures, each manganese atom can be unambigu-
ously assigned a formal +3 oxidation state. This is supported
by a bond length analysis, clearly revealing the expected Jahn–
Teller distortions (Table S1), by BVS calculations (Table S2),
and by additional agreement with magnetic properties and EPR
spectra. The most obvious difference in the eight title com-
pounds is found in the ligand shell, containing different func-
tional groups, which affect the packing of the molecules in the
crystal structures. Whereas the ligands observed in compounds
1–4 were previously reported as ligands to other manganese
complexes, as outlined below, the ligands used for the synthe-
ses and stabilization of 5–8 have no precedence in manganese
chemistry so far. The 4-hydroxybenzoate ligand in 1 (Fig-
ure 1), is mainly known in manganese(II) complexes.[8] Two
cases with MnIII atoms are known,[8a,b] not exceeding the nu-
clearity of two. The complex molecules in 1 aggregate into
chains extending along [101] (Figure 2, Table S1) via O–H···O
hydrogen bonds; hydroxyl groups from 4-hydroxybenzoate act
Compound 7 (Figure 1) represents the first manganese com-
plex with the 2-(methylthio)nicotinate ligand, which is mainly
known from copper(II) chemistry (see for instance[12]). The
complex molecules in 7 are arranged in layers parallel to (101),
also stabilized by a hydrogen bonding network (Table S3).
Compound 8 (Figure 1) contains the BOC-aminomethylbenzo-
ate ligand which has no precedence in any deposited crystal
structure so far. Disordered ethanol ligands that are bonded to
Mn3 and are hydrogen-bonded to the oxime O12 atom,
whereas the ordered ethanol ligand at Mn3 participates in
intermolecular hydrogen bonds, as the complexes interact via
as donors and oxygen atoms from coordinating oxime groups N–H···O and O–H···O hydrogen bonds (Table S3) to form
act as acceptors. The chains are interconnected by hydrogen chains extending along [100] (Figure S1).
764
www.zaac.wiley-vch.de
© 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
Z. Anorg. Allg. Chem. 2012, 763–769

A Series of [Mn6] Complexes with Terminal Functional Groups
Figure 1. Molecular structures of 1–8 (one symmetry-independent molecule in the case of 2, 3, 6, 7). The [Mn6O2] core is highlighted and an
atom labeling scheme is provided for the symmetry independent part of the [Mn6O2] core. Carbon and hydrogen atoms are shown as sticks, the
remaining atoms are denoted as spheres of arbitrary radii.
rate study. Figure 3 shows the according graphs for 1, 3, and
6–8 at 500 G.
For
1 the starting value for χT at 295.3 K is
14.82 cm3·mol·K–1, thus smaller than expected for six non-in-
teracting MnIII atoms (18.0 cm3·mol·K–1), which decreases
with decreasing temperature to 5.24 cm3·mol·K–1 at about 12
K; then a steep drop at lower temperatures is observed. 8
shows an analogous behavior, starting with χT of
15.84 cm3·mol·K–1 at 295.3 K, decreasing smoothly to
7.51 cm3·mol·K–1 at 15.50 K and remaining constant to about
14.0 K, followed by a final drop in χT. For 6, a similar behav-
ior with a more pronounced χT maximum at low temperatures
is present. The χT value of 6 decreases from 14.92 cm3·mol·K–
Figure 2. Hydrogen-bonded chains extending along [101] in 1. Hydro-
gen bonds are denoted by dashed lines. Only hydrogen atoms involved
in hydrogen bonds are shown. The symmetry-independent part of the
[Mn6O2] core is highlighted.
Preliminary Studies of the Magnetic Properties
at 295.3 K to 8.09 cm3·mol·K–1 at 20.5 K, followed by a
1
small rise to 8.18 cm3·mol·K–1 at 13.0 K and then a steep drop.
Compound 3 also exhibits antiferromagnetic interactions, but
shows modified features with respect to 1 and 6: the initial χT
value at 295.3 K is larger (16.31 cm3·mol·K–1), lowering more
distinctly to a well-defined minimum of 10.27 cm3·mol·K–1 at
29.5 K, followed by a much more pronounced rise to
12.45 cm3·mol·K–1 at 6.0 K. The magnetic behavior of com-
pound 7 is different. For 7, χT amounts to 15.08 cm3·mol·K–1
at 295.3 K, similar to the values observed for 1, 3 and 6, sug-
The magnetic susceptibility of the title compounds has been
examined as a function of the temperature as χT(T) at fields
of 500, 1000, 5000, or 10000 G, respectively. Also field-de-
pendent measurements have been carried out at 5 and 10 K.
Either antiferromagnetic (1–3, 6, 8) or ferromagnetic coupling
(4, 5, 7) of the six metal centers is observed. This seems to be
consistent with literature on this class of compounds, where
also a variable magnetic behavior is observed and correlated
with molecular geometric parameters.[7] However, some ano-
malies have been detected, in particular in the case of 2 and 5, gesting an antiferromagnetic coupling of the MnIII centers.
and secondary for 4, which needs careful checking and a sepa- Also, a decrease upon lowering of the temperature is observed
Z. Anorg. Allg. Chem. 2012, 763–769
© 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
www.zaac.wiley-vch.de
765

M. Hołyn´ska, S. Dehnen
ARTICLE
Figure 3. χT vs. T dependencies for 1, 3, and 6–8 at 500 G.
to reach 9.17 cm3·mol·K–1 at 42.5 K. However, at even lower spotlights these compounds with respect to further derivati-
temperatures
a sudden rise to a sharp maximum of zation and/or linkage. The new materials show either antiferro-
19.14 cm3·mol·K–1 at 5 K is observed. Compounds 2, 4 and 5 magnetic or ferromagnetic interactions, essentially in accord-
seem to be unusual in terms of too high/too low χT values. ance with known magneto-structural correlations. A pro-
The exploration and understanding of these anomalies are sub- nounced effect of intermolecular interactions involving func-
ject to a consecutive study.
tional groups is visible.
The observations described above were compared to the ex-
pectations based on the existing reports on oxime-bridged
[Mn6] complexes. The main idea is that there is a “magic area“
of Mn–N–O–Mn torsion angles.[7] A corresponding value of
less than 30.4° should result in antiferromagnetic coupling be-
tween the MnIII centers, whereas for values larger than 31.3°,
the coupling is expected to be ferromagnetic.[7] All magnetiza-
tion field-dependence curves (Figure S4) show a tendency
towards saturation, without pronounced hysteresis effects.
Experimental Section
General: All syntheses were carried out under aerobic conditions. All
chemicals were used without further purification. HPLC-grade meth-
anol (HiperSolv Chromanorm, VWR BDH Prolabo) was used. Abso-
lute ethanol purchased from AnalaR NORMAPUR was used. Tetraeth-
ylammonium hydroxide (25% solution in methanol) was purchased
from Aldrich and kept under argon. Manganese(II) perchlorate hexahy-
drate, 4-hydroxybenzoic acid, 4-aminobenzoic acid and 4-chloroben-
zoic acid were purchased from Aldrich. 4-(methylthio)benzoic acid
and (2-pyrimidylthio)acetic acid were purchased from Acros. Salicyl-
aldoxime was purchased from Merck. 2-(methylthio)nicotinic acid was
purchased from Alfa Aesar. 4-(Boc-aminomethyl)benzoic acid was
purchased from Fluka. 4-iodobenzoic acid was purchased from Fluo-
rochem. Caution! Although no particular problems were faced in case
of this work, it should be always taken into consideration that perchlo-
rates are explosive.
Thermal Behavior
The thermal behavior was examined for all title compounds
within a broad temperature range. All TG-DSC diagrams with
depicted mass losses are shown in the Supporting Information
(Figure S6). All compounds, except 4 and 8, showed a similar
general decomposition pattern: before achieving the melting
points (1: 254, 2: 215, 3: 247, 5: 265, 6: 206, 7: 253 °C) a
two-step small mass loss is observed, attributable to the release
of interstitial solvent (expected as the first step) and of solvent
molecules coordinated to manganese centers (expected as the
second step). Thus activated material obtained at this step
might be useful for further reactions. Upon melting, a multi-
step decomposition is observed, with the major step directly
following the melting point for 3, 6 and 7. For 4 and 8 the
stepwise decomposition includes different energetic effects.
Syntheses
[Mn6O2(MeOH)4(sao)6(HOC6H4COO)2]·2(H2O) (1): 4-hydroxyben-
zoic acid (0.138 g, 1 mmol), salicylaldoxime (0.137 g, 1 mmol) and
manganese(II) perchlorate hexahydrate (0.25 g, 1 mmol) were dis-
solved in methanol (20 mL) to afford a colorless solution. Sub-
sequently, tetraethylammonium hydroxide (1 mL) was added causing
darkening of the mixture. The mixture was stirred for 1 hour. The
obtained dark green solution was filtered and left for slow evaporation.
Crystals of 1 (dark plates showing red-green pleochroism) formed
within 7–10 days in 42% yield (with respect to salicylaldoxime). Ele-
mental anal. calcd. (found) for 1: C 44.74 (43.83), H 3.75 (3.44), N
Conclusions
A synthetic approach toward eight functionalized mixed-
valence polynuclear manganese complexes was shown which 5.22 (5.24) %. IR (KBr pellet) = 416.1 (m), 466.6 (m), 533.1 (w),
766 www.zaac.wiley-vch.de
© 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
Z. Anorg. Allg. Chem. 2012, 763–769

A Series of [Mn6] Complexes with Terminal Functional Groups
624.8 (s), 649.1 (s), 679.5 (vs), 749.5 (s), 788.4 (w), 827.8 (w), 855.8 1027.6 (vs), 1043.3 (s), 1124.0 (w), 1152.6 (w), 1202.0 (m), 1279.5
(w), 917.5 (vs), 1026.1 (vs), 1098.6 (m), 1124.4 (m), 1153.9 (m), (s), 1328.0 (w), 1394.8 (s), 1440.1 (s), 1471.0 (w), 1533.8 (m), 1582.1
1170.8 (m), 1202.5 (s), 1277.0 (vs), 1327.8 (w), 1392.5 (vs), 1440.0
(s), 1471.4 (m), 1527.9 (s), 1597.5 (vs), 3392.3 (s) cm–1.
(s), 1597.4 (s), 3437.2 (vw) cm–1.
[Mn6O2(MeOH)4(sao)6(pym-SCH2COO)2]·(MeOH) (6): (2-pyrimi-
dylthio)acetic acid (0.109 g, 1 mmol), salicylaldoxime (0.137 g,
1 mmol) and manganese(II) perchlorate hexahydrate (0.25 g, 1 mmol)
[Mn6O2(EtOH)4(sao)6(H2NC6H4COO)2]·1.85(EtOH) (2): of 4-ami-
nobenzoic acid (0.137 g, 1 mmol), salicylaldoxime (0.137 g, 1 mmol)
and manganese(II) perchlorate hexahydrate (0.25 g, 1 mmol) were dis- were dissolved in methanol (20 mL) to afford a yellow solution. Sub-
solved in a 1:1 mixture of ethanol and dichloromethane (20 mL) to
afford a yellow solution. Subsequently, tetraethylammonium hydroxide
(1 mL) was added causing darkening of the mixture. The mixture was
stirred for 1 hour. The obtained black solution was filtered from yel-
sequently, tetraethylammonium hydroxide (1 mL) was added causing
darkening of the mixture. The mixture was stirred for 1 hour. The
obtained black solution was filtered from black solid and left for slow
evaporation. Crystals of 6 (brown blocks) formed within 5–8 days in
lowish solid and left for slow evaporation. Crystals of 2 (black blocks) 25% yield (calculated with respect to salicylaldoxime). Elemental
formed within 6–10 days in 70% yield (with respect to salicylaldox- anal. calcd. (found) for 6: C 42.41 (41.20), H 3.62 (3.61), N 8.38
ime). Elemental anal. calcd. (found) for 2: C 47.19 (46.00), H 4.08 (8.34), S 3.84 (3.68) %. IR (KBr pellet) = 404.6 (vs), 414.5 (s), 424.2
(4.09), N 6.88 (6.98) %. IR (KBr pellet) = 416.3 (m), 463.2 (m), 534.3 (s), 463.4 (s), 527.6 (s), 649.7 (vs), 677.8 (vs), 753.7 (s), 824.7 (m),
(w), 648.7 (s), 677.0 (vs), 755.7 (m), 788.9 (w), 823.2 (vw), 852.3 863.8 (w), 915.5 (vs), 1025.9 (vs), 1124.4 (w), 1153.8 (m), 1200.5 (s),
(vw), 915.9 (vs), 1026.4 (vs), 1042.9 (s), 1123.7 (w), 1152.3 (w), 1285.9 (s), 1327.6 (m), 1381.8 (s), 1439.4 (m), 1471.7 (w), 1546.9
1176.1 (m), 1201.0 (m), 1282.6 (vs), 1325.1 (m), 1384.9 (vs), 1439.6 (m), 1569.2 (s), 1569.2 (s), 1598.1 (s), 3377.9 (vw) cm–1.
(s), 1471.1 (m), 1509.9 (s), 1540.9 (s), 1597.2 (vs), 3368.0 (vs) cm–1.
[Mn6O2(MeOH)2(H2O)2(sao)6(orto-CH3S-pyr-COO)2]0.75
[Mn6O2(MeOH)4(sao)6(orto-CH3S-pyr-COO)2]0.25
-
[Mn6O2(MeOH)4(sao)6(ClC6H4COO)2]·1.33(MeOH)·0.62(H2O) (3):
·
4-chlorobenzoic acid (0.156 g, 1 mmol), salicylaldoxime (0.137 g, 2.02(MeOH)·H2O (7): 2-(methylthio)nicotinic acid (0.169 g, 1 mmol),
1 mmol) and manganese(II) perchlorate hexahydrate (0.25 g, 1 mmol) salicylaldoxime (0.137 g, 1 mmol) and manganese(II) perchlorate
were dissolved in methanol (20 mL) to afford a colorless solution. Sub-
hexahydrate (0.25 g, 1 mmol) were dissolved in methanol (20 mL) to
sequently, tetraethylammonium hydroxide (1 mL) was added causing afford a yellow solution. Subsequently, tetraethylammonium hydroxide
darkening of the mixture. The mixture was stirred for 1 hour. The ob- (1 mL) was added causing darkening of the mixture. The mixture was
tained dark green solution was filtered and left for slow evaporation. stirred for 1 hour. The obtained black solution was filtered and left for
Crystals of 3 (black blocks) formed within 5–8 days in 37% yield (with
respect to salicylaldoxime). Elemental anal. calcd. (found) for 3: C
42.31 (41.93), H 3.21 (3.53), N 5.05 (5.13) %. IR (KBr pellet) = 463.7
(s), 534.6 (m), 649.1 (vs), 676.7 (vs), 755.3 (s), 826.1 (w), 858.5 (w),
916.2 (vs), 1027.3 (vs), 1043.6 (vs), 1090.4 (w), 1124.0 (w), 1153.3
(w), 1169.4 (w), 1201.4 (m), 1280.7 (vs), 1325.4 (w), 1398.5 (vs),
1439.8 (vs), 1471.2 (m), 1534.5 (vs), 1596.2 (vs), 3399.7 (s) cm–1.
slow evaporation. Crystals of 7 (violet needles) formed within 5–8
days in 22% yield (with respect to salicylaldoxime). Elemental anal.
calcd. (found) for 7: C 42.79 (40.57), H 3.86 (3.67), N 6.60 (6.60), S
3.78 (3.77) %. IR (KBr pellet) = 429.6 (m), 477.8 (s), 530.9 (m), 624.1
(s), 651.9 (s), 679.2 (vs), 752.1 (s), 826.7 (m), 917.4 (vs), 1026.9 (vs),
1041.8 (s), 1096.4 (s), 1153.3 (m), 1201.6 (m), 1283.4 (s), 1325.6 (w),
1376.0 (s), 1396.1 (m), 1440.1 (s), 1470.5 (m), 1536.8 (m), 1560.3
(m), 1582.6 (s), 1597.5 (s), 3001.1 (vw), 3407.9 (vw) cm–1.
[Mn6O2(MeOH)4(sao)6(CH3SC6H4COO)2]·5.37(MeOH) (4): 4-
(methylthio)benzoic acid (0.172 g, 1 mmol), salicylaldoxime (0.137 g, [Mn6O2(EtOH)4(sao)6(Me3OOCNHCH2C6H4COO)2] (8). 4-(boc-
1 mmol) and manganese(II) perchlorate hexahydrate (0.25 g, 1 mmol) aminomethyl)benzoic acid (0.125 g, 0.5 mmol), salicylaldoxime
were dissolved in methanol (20 mL) to afford a colorless solution. Sub-
sequently, tetraethylammonium hydroxide (1 mL) was added causing
(0.137 g, 1 mmol) and manganese(II) perchlorate hexahydrate (0.25 g,
1 mmol) were dissolved in a 1:1 mixture of ethanol and dichlorometh-
darkening of the mixture. The mixture was stirred for 1 hour. The ane (20 mL) to afford a colorless solution. Subsequently, tetraethylam-
obtained black solution was filtered from greenish solid and left for monium hydroxide (1 mL) was added causing darkening of the mix-
slow evaporation. Crystals of 4 (black blocks) formed within 5–8 days ture. The mixture was stirred for 1 hour. The obtained dark brown
in 42% yield (with respect to salicylaldoxime). Elemental anal. calcd.
(found) for 4: C 44.78 (43.11), H 4.54 (5.41), N 4.65 (5.49), S 3.55
solution was filtered and left for slow evaporation. Crystals of 8 (in
form of black blocks) were formed within 7–14 days at 48% yield
(2.45) %. IR (KBr pellet) = 462.2 (s), 531.5 (s), 650.2 (vs), 678.3 (vs), (calculated with respect to salicylaldoxime). Elemental anal. Calcd
751.8 (s), 777.3 (m), 824.5 (w), 854.7 (w), 915.8 (vs), 957.3 (w), (found) for 8: C 49.26 (47.01), H 4.46 (4.72), N 6.05 (6.20) %. IR
1026.7 (vs), 1043.7 (vs), 1091.3 (m), 1123.2 (m), 1151.7 (m), 1185.1 (KBr pellet) = 408.3 (m), 418.1 (m), 467.1 (s), 529.7 (m), 676.1 (vs),
(m), 1200.8 (s), 1278.7 (vs), 1326.7 (m), 1396.5 (vs), 1440.1 (vs), 750.3 (s), 765.3 (m), 825.5 (w), 873.5 (w), 916.3 (s), 1001.0 (m),
1470.5 (s), 1523.1 (vs), 1541.6 (s), 1597.0 (vs), 3414.1 (vs) cm–1.
1029.5 (s), 1045.3 (s), 1074.1 (w), 1162.5 (m), 1200.6 (m), 1278.0 (s),
1324.9 (w), 1398.1 (s), 1443.1 (m), 1472.7 (w), 1535.8 (s), 1598.4
(m), 1712.0 (m) cm–1.
[Mn6O2(MeOH)4(sao)6(I-C6H4COO)2]·4.7(MeOH) (5): 4-iodoben-
zoic acid (0.248 g, 1 mmol), salicylaldoxime (0.137 g, 1 mmol) and
manganese(II) perchlorate hexahydrate (0.25 g, 1 mmol) were dis- Physical Property Measurements: IR spectra were collected with the
solved in methanol (20 mL) to afford a colorless solution. Sub-
sequently, tetraethylammonium hydroxide (1 mL) was added causing
aid of a Bruker IFS 88 device. EPR spectra were collected for solid
samples in quartz tubes at room and at helium temperature by using a
darkening of the mixture. The mixture was stirred for 1 hour. The Bruker ESP300 device. ESI-MS spectra were collected by means of a
obtained black solution was filtered and left for slow evaporation. Finnigan LTQ-FT spectrometer for acetonitrile solutions of 1–8. TGA
Crystals of 5 (black needles) formed within 5–8 days in 38% yield diagrams for samples of 1–8 (1: 16.9, 2: 7.9, 3: 20.2, 4: 6.9, 5: 8.3, 6:
(with respect to salicylaldoxime). Elemental anal. calcd. (found) for 13.9, 7: 11.1, 8: 11.6 mg) were recorded with a NETZSCH STA 409
5: C 39.96 (37.59), H 3.72 (2.91), N 4.34 (4.34), I 13.12 (12.76) %. CD device at temp. range of 25–1450 °C and scanning rate of 1 K·min–
IR (KBr pellet) = 409.7 (s), 424.6 (s), 464.6 (s), 536.1 (m), 649.1 (s),
680.5 (vs), 752.1 (s), 831.5 (m), 853.9 (w), 916.9 (vs), 1007.1 (s), using a Quantum Design SQUID Magnetometer for samples of 1–8
1. Preliminary magnetic properties measurements were carried out by
Z. Anorg. Allg. Chem. 2012, 763–769
© 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
www.zaac.wiley-vch.de
767

M. Hołyn´ska, S. Dehnen
(1: 15.4, 2: 7.4, 3: 35.0, 4: 16.5, 5: 17.7, 6: 13.9, 7: 22.8, 8: 9.8 mg) Supporting Information (see footnote on the first page of this article):
ARTICLE
in gelatine capsule holders at 2–300 K temperature range. The values
were accordingly corrected for the sample holder. Four values of exter-
nal field were applied (500/1000/5000/10000 G). Also field-dependent
measurements at 5 K/10 K were carried out. Diamagnetic corrections
were introduced using Pascal constants.[13] Here only selected results
are shown. Especially the behavior of 2, 4, and 5 seems to be unusual
and requires further studies.
Details of X-ray structure refinement, EDX measurement results, ther-
mogravimetric diagrams, magnetic properties.
Acknowledgments
This work was supported by the Alexander von Humboldt Foundation.
Help of Dr. O. Burghaus (EPR spectra), R. Riedel (X-ray data collec-
tion), C. Pietzonka (magnetic properties investigation), J. Bamberger
(mass spectrometry), M. Hellwig (EDX) and C. Mischke (IR spectra)
is gratefully acknowledged.
X-ray Crystallography: X-ray data were collected at 100(2) K with
IPDS2 or IPDS2T diffractometers or at 193(2) K with an IPDS1 dif-
fractometer,[14] using graphite-monochromatized Mo-Kα radiation (λ =
0.71073 Å). The structures were solved by direct methods and refined
on F2 by full-matrix least-squares methods using the SHELXTL pro-
gram package.[15] Crystal data for 1: (M = 1610.78 g·mol–1): triclinic,
References
[1] T. Lis, Acta Crystallogr., Sect. B 1980, 36, 2042.
¯
space group P1 (no. 2), a = 11.732(3), b = 11.934(3), c = 12.835(4) Å,
[2] a) D. Gatteschi, R. Sessoli, Angew. Chem. 2003, 115, 278; Angew.
Chem. Int. Ed. 2003, 42, 268; b) G. Christou, D. Gatteschi, D. N.
Hendrickson, R. Sessoli, MRS Bull. 2000, 25, 66.
[3] L. Zobbi, M. Mannini, M. Pacchioni, G. Chastanet, D. Bonacchi,
C. Zanardi, R. Biagi, U. Del Pennino, D. Gatteschi, A. Cornia, R.
Sessoli, Chem. Commun. 2005, 1640.
[4] a) G. Christou, Polyhedron 2005, 24, 2065; b) K. V. Shuvaev,
L. N. Dawe, L. K. Thompson, Eur. J. Inorg. Chem. 2010, 29,
4583.
α = 105.94(3), β = 104.59(3), γ = 98.04(3)°, V = 1629.5(8) Å3, Z = 1,
Dc = 1.641 g·cm–3, μ = 1.22 mm–1, 13520 reflections measured (R(int)
= 0.115), 6806 unique, 2958 with I Ͼ 2σ(I) and final R values R1 =
0.066 [I Ͼ 2σ(I)); wR2 = 0.104 (all data). Crystal data for 2: (M =
1714.03 g·mol–1): monoclinic, space group P21/c (no. 14), a =
19.970(4), b = 27.694(5), c = 13.945(4) Å, β = 94.20(3)°, V =
7692(3) Å3, Z = 4, Dc = 1.480 g·cm–3, μ = 1.03 mm–1, 37157 reflec-
tions measured (R(int) = 0.070), 15819 unique, 5415 with I Ͼ 2σ(I)
[5] a) Z. Hassanzadeh Fard, L. Xiong, C. Müller, M. Hołyn´ska, S.
Dehnen, Eur. J. Chem. Eur. J. Chem. 2009, 15, 6595; b) Z. Has-
sanzadeh Fard, C. Müller, T. Harmening, R. Pöttgen, S. Dehnen,
Angew. Chem. 2009, 121, 4507; Angew. Chem. Int. Ed. 2009, 48,
4441; c) M. R. Halvagar, Z. Hassanzadeh Fard, L. Xiong, S.
Dehnen, Inorg. Chem. 2009, 48, 7373; d) Z. Hassanzadeh Fard,
M. R. Halvagar, S. Dehnen, J. Am. Chem. Soc. 2010, 32, 2848.
[6] a) F. Zonnevijlle, M. T. Pope, J. Am. Chem. Soc. 1979, 101, 2731;
b) S. Bareyt, S. Piligkos, B. Hasenknopf, P. Gouzerh, E. Lacote,
S. Thorimbert, M. Malacri, Angew. Chem. 2003, 115, 3526; An-
gew. Chem. Int. Ed. 2003, 42, 3404; c) S. Bareyt, S. Piligkos, B.
Hasenknopf, P. Gouzerh, E. Lacote, S. Thorimbert, M. Malacria,
J. Am. Chem. Soc. 2005, 127, 6788.
[7] a) C. J. Milios, A. Vinslava, W. Wernsdorfer, S. Moggach, S. Par-
sons, S. P. Perlepes, G. Christou, E. K. Brechin, J. Am. Chem.
Soc. 2007, 129, 2754; b) C. J. Milios, R. Inglis, A. Vinslava, R.
Bagai, W. Wernsdorfer, S. Parsons, S. P. Perlepes, G. Christou,
E. K. Brechin, J. Am. Chem. Soc. 2007, 129, 12505; c) R. Inglis,
L. F. Jones, C. J. Milios, S. Datta, A. Collins, S. Parsons, W.
Wernsdorfer, S. Hill, S. P. Perlepes, S. Piligkos, E. K. Brechin,
Dalton Trans. 2009, 3403; d) L. F. Jones, M. E. Cochrane, B. D.
Koivisto, D. A. Leigh, S. P. Perlepes, W. Wernsdorfer, E. K. Bre-
chin, Inorg. Chim. Acta 2008, 361, 3420; e) A. Prescimone, C. J.
Milios, J. Sanchez-Benitez, K. V. Kamenev, C. Loose, J. Kortus,
S. Moggach, M. Murrie, J. E. Warren, A. R. Lennie, S. Parsons,
E. K. Brechin, Dalton Trans. 2009, 4858; f) C. J. Milios, C. P.
Raptopoulou, A. Terzis, F. Lloret, R. Vicente, S. P. Perlepes, A.
Escuer, Angew. Chem. 2004, 116, 212; Angew. Chem. Int. Ed.
2004, 43, 210; g) A. Prescimone, C. J. Milios, S. Moggach, J. E.
Warren, A. R. Lennie, J. Sanchez-Benitez, K. Kamenev, R. Bir-
cher, M. Murrie, S. Parsons, E. K. Brechin, Angew. Chem. 2008,
120, 2870; Angew. Chem. Int. Ed. 2008, 47, 2828; h) C.-I. Yang,
K.-H. Cheng, M. Nakano, G.-H. Lee, H.-L. Tsai, Polyhedron
2009, 28, 1842; i) F. Moro, V. Corradini, M. Evangelisti, V.
De Renzi, R. Biagi, U. del Pennino, C. J. Milios, L. F. Jones,
E. K. Brechin, J. Phys. Chem. B 2008, 112, 9729; j) L. F. Jones,
C. J. Milios, A. Prescimone, M. Evangelisti, E. K. Brechin, C. R.
Chim. 2008, 11, 1175; k) X. Song, R. Liu, S. Zhang, L. Li, Inorg.
Chem. Commun. 2010, 13, 828; l) R. Inglis, L. F. Jones, C. J.
Milios, S. Datta, A. Collins, S. Parsons, W. Wernsdorfer, S. Hill,
S. P. Perlepes, S. Piligkos, E. K. Brechin, Dalton Trans. 2009,
3403; m) C. J. Milios, A. Vinslava, W. Wernsdorfer, A. Presci-
mone, P. A. Wood, S. Parsons, S. P. Perlepes, G. Christou, E. K.
and final R values R1 = 0.062 [I Ͼ 2σ(I)); wR2 = 0.097 (all data).
Crystal data for 3: (M = 1665.42 g·mol ): triclinic, space group P1
–1
¯
(no. 2), a = 12.742(3), b = 15.080(4), c = 19.081(4) Å, α = 88.03(3),
β = 73.89(3), γ = 80.57(3)°, V = 3474.6(14) Å3, Z = 2, Dc
=
1.592 g·cm–3, μ = 1.22 mm–1, 29015 reflections measured (R(int) =
0.058), 14530 unique, 8807 with I Ͼ 2σ(I) and final R values R1 =
0.057 [I Ͼ 2σ(I)); wR2 = 0.130 (all data). Crystal data for 4: (M =
–1
¯
1807.33 g·mol ): triclinic, space group P1 (no. 2), a = 11.090(3), b =
13.772(4), c = 14.838(4) Å, α = 116.06(3), β = 95.37(3), γ =
103.36(3)°, V = 1930.8(9) Å3, Z = 1, Dc = 1.554 g·cm–3, μ = 1.09 mm–
1, 14410 reflections measured (R(int) = 0.064), 6705 unique, 4331 with
I Ͼ 2σ(I) and final R values R1 = 0.057 [I Ͼ 2σ(I)); wR2 = 0.145 (all
data). Crystal data for 5: (M = 1945.13 g·mol–1): triclinic, space group
¯
P1 (no. 2), a = 10.443(3), b = 14.607(4), c = 15.124(4) Å, α =
117.01(3), β = 93.47(3), γ = 104.40(3)°, V = 1950.2(9) Å3, Z = 1, Dc
= 1.656 g·cm–3, μ = 1.81 mm–1, 17732 reflections measured (R(int) =
0.097), 6471 unique, 4439 with I Ͼ 2σ(I) and final R values R1 =
0.059 [I Ͼ 2σ(I)); wR2 = 0.153 (all data). Crystal data for 6: (M =
1670.93 g·mol–1): monoclinic, space group P21/c (no. 14), a =
23.702(5), b = 12.399(4), c = 29.701(5) Å, β = 128.62(3)°, V =
6820(3) Å3, Z = 4, Dc = 1.627 g·cm–3, μ = 1.22 mm–1, 30616 reflec-
tions measured (R(int) = 0.043), 11405 unique, 9280 with I Ͼ 2σ(I)
and final R values R1 = 0.038 [I Ͼ 2σ(I)); wR2 = 0.097 (all data).
–1
¯
Crystal data for 7: (M = 1698.61 g·mol ): triclinic, space group P1
(no. 2), a = 12.453(3), b = 12.986(3), c = 22.401(4) Å, α = 87.16(3),
β = 80.71(3), γ = 72.82(3)°, V = 3415.5(13) Å3, Z = 2, Dc
=
1.656 g·cm–3, μ = 1.23 mm–1, 20192 reflections measured (R(int) =
0.104), 10985 unique, 8555 with I Ͼ 2σ(I) and final R values R1 =
0.062 [I Ͼ 2σ(I)); wR2 = 0.202 (all data). Crystal data for 8: (M =
–1
¯
1853.14 g·mol ): triclinic, space group P1 (no. 2), a = 11.961(3), b =
12.204(3), c = 14.720(4) Å, α = 108.94(3), β = 92.44(3), γ = 93.87(3)°,
V = 2023.0(9) Å3, Z = 1, Dc = 1.521 g·cm–3, μ = 0.99 mm–1, 30333
reflections measured (R(int) = 0.098), 8574 unique, 6228 with I Ͼ
2σ(I) and final R values R1 = 0.057 [I Ͼ 2σ(I)); wR2 = 0.151 (all data).
The supplementary crystallographic data CCDC-807708, -807709, -
807710, -807711, -807712, -807713, -807714, -807715 (1–8) can be
obtained free of charge from The Cambridge Crystallographic Data
Center via www.ccdc.cam.ac.uk.data_request.cif.
768
www.zaac.wiley-vch.de
© 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
Z. Anorg. Allg. Chem. 2012, 763–769

A Series of [Mn6] Complexes with Terminal Functional Groups
Brechin, J. Am. Chem. Soc. 2007, 129, 6547; n) C. J. Milios, R. [11] a) C. Ma, Y. Han, R. Zhang, J. Organomet. Chem. 2004, 689,
Inglis, R. Bagai, W. Wernsdorfer, A. Collins, S. Moggach, S. Par-
sons, S. P. Perlepes, G. Christou, E. K. Brechin, Chem. Commun.
2007, 3476; o) C. J. Milios, R. Inglis, A. Vinslava, R. Bagai, W.
Wernsdorfer, S. Parsons, S. P. Perlepes, G. Christou, E. K. Bre-
chin, J. Am. Chem. Soc. 2007, 129, 12505; p) V. Kotzabasaki, R.
Inglis, M. Siczek, T. Lis, E. K. Brechin, C. J. Milios, Dalton
Trans. 2011, 40, 1693.
1675; b) H.-Q. Hao, H. Zhang, J.-G. Chen, S. W. Ng, Acta Crys-
tallogr., Sect. E 2005, 61, m1960; c) L. Han, Y. Zhou, S.-J. Huang,
Acta Crystallogr., Sect. E 2007, 63, m455; d) H.-Q. Hao, H.
Zhang, Acta Crystallogr., Sect. E 2006, 62, m30.
[12] D. Miklos, M. Palicova, P. SeglЈa, M. Melnik, M. Korabik, T.
Głowiak, J. Mrozin´ski, Z. Anorg. Allg. Chem. 2002, 628, 2862.
[13] E. König, in: Magnetic Properties of Coordination and Organo-
metallic Transition Metal Compounds (Eds.: K. H. Hellwege,
A. M. Hellwege), Springer, Berlin, 1966, pp. 27–29.
[8] a) R. Reshma, P. V. Soumya, S. M. Simi, V. S. Thampidas, R. D.
Pike, Acta Crystallogr., Sect. E 2009, 65, m1110; b) H. Liu, J.
Tian, Y. Kou, J. Zhang, L. Feng, D. Li, W. Gu, X. Liu, D. Liao,
P. Cheng, J. Ribas, S. Yan, Dalton Trans. 2009, 10511; c) J.-R.
Su, L. Zhang, D.-J. Xu, Acta Crystallogr., Sect. E 2005, 61, m939.
[9] C. Kozoni, E. Manolopoulou, M. Siczek, T. Lis, E. K. Brechin,
C. J. Milios, Dalton Trans. 2010, 39, 7943.
[14] Stoe & Cie, X-AREA (Version 1.54) and X-RED32 (Version 1.54),
Stoe & Cie, Darmstadt, Germany 2002.
[15] G. M. Sheldrick, SHELXTL 5.1, Bruker AXS Inc., 6300 Enter-
prise Lane, Madison, WI 53719–1173, USA, 1997.
[10] S. M. J. Aubin, Z. Sun, H. J. Eppley, E. M. Rumberger, I. A. Gu-
zei, K. Folting, P. K. Gantzel, A. L. Rheingold, G. Christou, D. N.
Hendrickson, Inorg. Chem. 2001, 40, 2127.
Received: December 4, 2011
Published Online: March 8, 2012
Z. Anorg. Allg. Chem. 2012, 763–769
© 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
www.zaac.wiley-vch.de
769