Structural, electrochemical and magnetic analyses of a new octanuclear MnIII2MnII6 cluster with linked-defect cubane topology

Article abstract of DOI:10.1039/c5ce02215k

The employment of the 3,5-dimethyl-1-(hydroxymethyl)-pyrazole (Hdmhmp) ligand in a manganese carboxylate cluster afforded the new mixed-valent octanuclear manganese cluster [Mn^III₂Mn^II₆O₂(PhCOO)₁₀(dmhmp)₄(H₂O)₂]·4CH₃CN (1). Complex 1 was isolated by the reaction of Mn(ClO₄)₂·6H₂O, Hdmhmp and benzoic acid in a mixed solvent of acetonitrile and methanol. The structure of 1 can be described as a μ₄-O^2--linked pair of [Mn₄O₃] defect cubanes protected by ten PhCO₂^- and four μ₃-dmhmp^- ligands. Complex 1 is slightly soluble in acetonitrile, and high-resolution electrospray mass spectrometry (HRESI-MS) indicated that it could keep the [Mn^III₂Mn^II₆O₂] core integrity in solution but with detectable ligand exchange between PhCOO^- and dmhmp^-. The electrochemical studies show that 1 possesses a characteristic Mn^II → Mn^III oxidation peak at +0.82 V and Mn^III → Mn^II reduction peaks at-0.79 and-1.51 V (versus Fc/Fc⁺), respectively. A detailed magnetic properties investigation has revealed only a weak intramolecular antiferromagnetic interaction between the Mn^II and Mn^III ions and no characteristic single-molecule magnetic properties.

Full text of DOI:10.1039/c5ce02215k

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Structural, electrochemical and magnetic analyses
of a new octanuclear MnIII MnII cluster with
2
6
Cite this: DOI: 10.1039/c5ce02215k
linked-defect cubane topology†
a
a
a
c
b
*
Fei Yang,‡ Yong-Kai Deng,‡ Ling-Yu Guo,‡ Hai-Feng Su, Zvonko Jagličić,
a
d
e
a
*
*
Zhen-Yu Feng, Gui-Lin Zhuang, Su-Yuan Zeng and Di Sun
The employment of the 3,5-dimethyl-1-(hydroxymethyl)-pyrazole (Hdmhmp) ligand in a manganese car-
boxylate cluster afforded the new mixed-valent octanuclear manganese cluster [MnIII2MnII6O2IJPhCOO)10
-
IJdmhmp)4IJH2O)2]·4CH3CN (1). Complex 1 was isolated by the reaction of MnIJClO4)2·6H2O, Hdmhmp and
benzoic acid in a mixed solvent of acetonitrile and methanol. The structure of 1 can be described as a μ4-
2−-linked pair of [Mn4O3] defect cubanes protected by ten PhCO2 and four μ3-dmhmp− ligands. Com-
−
O
plex 1 is slightly soluble in acetonitrile, and high-resolution electrospray mass spectrometry (HRESI-MS) in-
dicated that it could keep the [MnIII2MnII6O2] core integrity in solution but with detectable ligand exchange
between PhCOO− and dmhmp−. The electrochemical studies show that 1 possesses a characteristic MnII →
MnIII oxidation peak at +0.82 V and MnIII → MnII reduction peaks at −0.79 and −1.51 V (versus Fc/Fc+), re-
spectively. A detailed magnetic properties investigation has revealed only a weak intramolecular antiferro-
magnetic interaction between the MnII and MnIII ions and no characteristic single-molecule magnetic
properties.
Received 12th November 2015,
Accepted 22nd January 2016
DOI: 10.1039/c5ce02215k
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coupled with significant magnetoanisotropy of the Ising
(easy-axis) type, then such clusters become single-molecule
Introduction
Polynuclear manganese clusters have attracted great interest
given their relevance to various applications, mainly including
molecular magnetic materials and as model compounds of
oxygen-evolving centers (OECs) in bioinorganic chemistry,
and given their structural aesthetics.1 As molecular magnets,
manganese clusters often possess large numbers of unpaired
electrons from 3d orbitals, offering large ground state spin
values from ferromagnetic exchange interactions,2 and if
magnets (SMMs).3 In green plants, the pentanuclear CaMn4
cluster (cubane [Mn3Ca] + a fourth Mn) was confirmed to be
the active sites of OECs in Photosystem II, as revealed by its
crystal structure at 1.9 Å resolution.4 From then on, many syn-
thetic chemists started to mimic manganese-based clusters as
artificial catalysts for the visible-light splitting of water to mo-
lecular dioxygen through a 4e process.5 The preparation and
detailed study of such closely-related manganese clusters,
similar to the CaMn4 cluster, would greatly deepen our under-
standing of the spectroscopic, physical and catalytic mecha-
nism of the water oxidation catalyst. The groups of Christou,
Powell, Winpenny and Tong have developed versatile bridging
and/or chelating ligands including aliphatic or aromatic alco-
hols,6 alcohol amines,7 di-2-pyridyl ketone,8 pyridyl alcohols9
and pyridyl ketone oximes10 to construct polynuclear manga-
nese clusters, and many fascinating products have been iso-
lated; however, a hydroxymethyl-pyrazole ligand-based manga-
nese cluster has never been seen in the literature.
a Key Lab of Colloid and Interface Chemistry, Ministry of Education, School of
Chemistry and Chemical Engineering, Shandong University, Jinan, 250100, PR
China. E-mail: dsun@sdu.edu.cn
b Faculty of Civil and Geodetic Engineering & Institute of Mathematics, Physics
and Mechanics, University of Ljubljana, Jamova 2, 1000 Ljubljana, Slovenia.
E-mail: zvonko.jaglicic@imfm.si
c State Key Laboratory for Physical Chemistry of Solid Surfaces and Department of
Chemistry, College of Chemistry and Chemical Engineering, Xiamen University,
Xiamen, 361005, People's Republic of China
d College of Chemical Engineering and Materials Science, Zhejiang University of
Technology, Hangzhou, 310032, People's Republic of China.
E-mail: glzhuang@zjut.edu.cn
As we know, the hydroxymethyl-pyrazole ligand11a con-
tains both aromatic pyrazole and a flexible hydroxymethyl
arm; the latter, upon deprotonation, usually acts as a bridg-
ing group and thus favors the formation of polynuclear prod-
ucts. However, the rarity of its polynuclear metal clusters may
be due to its instability related to the decomposition reverse
reaction, especially in the presence of CuII atoms.11b,11c For
e School of Chemistry and Chemical Engineering, Liaocheng University, Liaocheng,
People's Republic of China
† Electronic supplementary information (ESI) available: Tables, TGA, powder
X-ray diffractogram, IR and crystal data in CIF files, for 1. CCDC 1423562. For
ESI and crystallographic data in CIF or other electronic format see DOI: 10.1039/
c5ce02215k
‡ These authors contributed equally.
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the above reasons and more, there is a continuing necessity
to achieve new polynuclear Mn clusters. One important explo-
ration in our group is to design and synthesise new alcohol-
containing chelating/bridging ligands involving controllable
bulk near the alkoxide group, and then to check their desir-
ability for developing new clusters and functionalities. Initial
work has concentrated on 3,5-dimethyl-1-(hydroxymethyl)-
pyrazole (Hdmhmp), which is the first alcohol-containing li-
gand used in the construction of polynuclear Mn cluster
chemistry. In the present work, we present (i) the usage of
mixed Hdmhmp and benzoic acid in a reaction with a Mn
salt (Scheme 1), (ii) the structure and solution behavior of
this octanuclear mixed-valent Mn cluster and (iii) its electro-
chemical and magnetic properties. This work not only pro-
vides a hydroxymethyl-pyrazole-based Mn cluster, but also
deepens our understanding of Mn cluster assembly and re-
lated properties in solution and in the solid state.
Results and discussion
Crystal structural description
Fig.
1
Molecular
structures
of
the
[MnIII2MnII6O2IJPhCOO)10IJdmhmp)4IJH2O)2] (a) and the opened bicubane
X-ray crystallographic analysis indicated that 1 is a neutral
cluster comprised of eight Mn atoms, which crystallizes in
motif in 1 (b). H atoms are omitted for clarity. Colour code: MnII
purple; MnIII = green; O = red; N = blue; C = gray.
=
¯
the triclinic space group P1. The cluster 1 is located on a crys-
tallographic inversion center and has Ci point symmetry. The
asymmetric unit of 1 contains one half of the octanuclear
cluster with eight Mn atoms, four dmhmp−, ten PhCOO−, two
oxo anions and two coordinated aqua ligands. As shown in
Fig. 1a, all Mn atoms have six-coordinated octahedral geome-
try. Mn1 and Mn4 are in the MnNO5 octahedral geometry,
whereas Mn2 and Mn3 are in MnO6 octahedral geometry.
The Mn–O bond lengths range from 1.878(3) to 2.462(4) Å
and the Mn–N bond length is 2.187(5) Å, which is similar to
those observed in many mixed-valent Mn clusters.12 Notably,
the longest Mn–O bonding distance (Mn2–O1 = 2.462(4) Å)
indicates the presence of a MnIII Jahn–Teller (JT) distortion
(axial elongations) for Mn2.13 Bond valence sum (BVS) calcu-
lations were performed for the atoms Mn1–Mn4. As expected,
Mn2 is in a +3 oxidation state and the remaining Mn atoms
are +2 (Table 1). Considering the charge neutrality, the core
of 1 should be assigned to [MnIII2MnII6], which is linked by
μ4-O2− and μ3-Odmhmp bridges to form an opened bicubane
motif (Fig. 1b). The origination of the MnIII should be the in
situ oxidation of MnII by oxygen in air. The junction of two
opened cubanes contains two Mn2–O11i and Mn2i–O11 edges
as well as two μ2-OPhCOO bridges. Within the core, the
Mn⋯Mn separations are in the range of 2.8011IJ17)–
3.5086IJ13) Å with an average value of 3.223 Å. The overall core
is protected by ten PhCO2 , four μ3-dmhmp− ligands and two
−
terminal aqua ligands. It should also be noted that the
PhCOO− ligands show three coordination modes: four as μ3-
O1:O′2 bridges, four as μ2-O1:O′1 bridges and the last two as
terminal monodentate ligands bound to Mn1. The aqua li-
gand binds to Mn3 and forms intramolecular H-bonding with
unbound O8 of the monodentate PhCOO− ligand (O1W⋯O8
= 2.76 Å). In addition, the aqua ligand also forms inter-
molecular H-bonding with another centrosymmetric O8 atom
Table 1 BVS calculations for the Mn atoms of 1
Atom
MnII
MnIII
MnIV
Mn1
Mn2
Mn3
Mn4
2.133
3.290
1.714
2.145
2.000
3.034
1.580
2.011
1.971
2.977
1.551
1.981
The italicised value is the one closest to the charge for which it was
calculated.
Scheme 1 The synthesis of the ligand and the assembly route of
cluster 1.
The oxidation state can be taken as the integer nearest to the
italicised value.
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with a O1W⋯O8 distance of 2.74 Å. The intra- and inter-
molecular hydrogen bonds construct a R24(8) motif based on
the graph set analysis nomenclature.14a As we know and as
the summarized examples in a comprehensive review by Pow-
ell demonstrate,14b octanuclear Mn clusters have very rich
geometries.15–22 However, the linked defect-dicubane core in
1 is not common, having been seen only two times before in
Mn cluster chemistry.23
be replaced by other ligands, and that it even more actively
binds on the empty metal center left by other dissociated li-
gands, indicating that the dmhmp− is a strong multidentate
ligand. Compared to the numbers of PhCOO− and aqua li-
gands in the solid state structure of 1, some of them dissoci-
ated from the Mn8O2 core in the solution, suggesting that the
monodentate PhCOO− and terminal aqua are the most labile
ligands once dissolved in solution.
Stability in solution of the Mn8 cluster
Electrochemistry
Mass spectrometry has been justified as a miscellaneous tool
to i) check the solid structure integrity once dissolved in sol-
vents,24 ii) examine the composition of the possible molecu-
lar species under the complex coordination-dissociation equi-
libria and the abundance of corresponding species,25 and
even iii) establish the catalytic mechanism in solution and
track the formation mechanism of polynuclear metal clus-
ters.26 In order to check the integrity of the Mn8 cluster in so-
lution and its coordination-dissociation behavior, crystals of
1 were dissolved in CH3CN and probed by high-resolution
electrospray mass spectrometry (HRESI-MS) at a dry gas tem-
perature of 40 °C. The HRESI-MS shows four main signals at
m/z = 1999.020, 2003.066, 2061.048 and 2065.078 in the
positive-ion mode, and the last peak is the most abundant in
the m/z range of 1000–2500. These four signals can be attrib-
uted to Mn8 intact cluster species, which are assigned to
As we know, Mn atoms in coordination cluster compounds
can exhibit II, III and IV valences, and thus mixed-valent clus-
ters such as the famous Mn12 molecular magnet usually show
rich redox behavior, involving multistep quasi-reversible oxi-
dation and reduction processes.27 In addition, the electronic
effect of ligands, as expected, also influences the redox poten-
tials.28 Thus, for the new mixed-valent Mn cluster, the
electrochemical behavior deserved to be tested. To this pur-
pose, the electrochemical properties of 1 were studied in a
n
MeCN solution, in the presence of Bu4NPF6 (TBFP; 0.1 M) as
a supporting electrolyte, using cyclic and differential pulse
voltammetry (CV and DPV) at room temperature. As shown in
Fig. 3, there are two quasi-reversible reduction peaks at −0.79
and −1.51 V (versus Fc/Fc+), respectively, which should be
assigned to the two-step consecutive reduction of two MnIII
to two MnII. The oxidation of MnII to MnIII occurred at +0.82
V, which is similar to the MnII → MnIII oxidation potential
[Mn8O2IJPhCOO)8IJdmhmp)4IJCH3CO2)]+ (m/z
[Mn8O2IJPhCOO)7IJdmhmp)5IJCH3CO2)]+ (m/z
=
=
1999.020),
2003.066),
observed
in
another
octanuclear
cluster
[Mn8O2IJPhCOO)9IJdmhmp)4]+
(m/z
=
2061.048)
and
[Mn8O6Cl6IJPhCOO)7IJH2O)2]−.29
[Mn8O2IJPhCOO)8IJdmhmp)5]+ (m/z = 2065.078) by comparing
the experimental isotopic envelopes with those simulated
(Fig. 2). Comparing the parent formula of 1,
[Mn8O2IJPhCOO)10IJdmhmp)4IJH2O)2], we found that the solu-
tion species presents different degrees of dissociation and
substitution between dmhmp−, PhCOO−, aqua and CH3COO−;
however, the Mn8O2 core is kept intact in solution. In the
competitive and complex coordination-dissociation equilib-
ria, we found that the coordinated dmhmp− was difficult to
Fig. 3 Cyclic voltammogram at 100 mV s−1 (top) and differential pulse
voltammogram (bottom) for 1 in CH3CN containing 0.1 M nBu4NPF6 as
supporting electrolyte. The indicated potentials are vs. Fc/Fc+.
Fig. 2 The positive-ion mode HR-ESI mass spectrum of 1 dissolved in
CH3CN.
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Magnetic properties
properties such as step-like hysteresis32 or a frequency-
dependent out-of-phase ac susceptibility signal.23b
Temperature-dependent magnetic susceptibility and the ef-
fective magnetic moment on the crystalline sample were mea-
sured in a magnetic field of 1000 Oe (Fig. 4). All presented
data have been corrected for a temperature-independent dia-
magnetic contribution of inner shell electrons as obtained
from Pascal's tables.30
The susceptibility decreases with increasing temperature
while the effective magnetic moment linearly increases be-
tween 50 K and room temperature. The expected average ef-
fective magnetic moment per manganese ion for a molecule
In Fig. 5, isothermal magnetization curves at temperatures
7 K, 5 K and 2 K are shown. The curves were analysed by ap-
plying a fit with a Brillouin function for S = J = 5/2 isolated
magnetic moments. At the temperature of 7 K, where the
weak antiferromagnetic interaction is not yet very effective,
the fit is good. With decreasing temperature, the fit with the
Brillouin function becomes unsatisfactory. Due to the antifer-
romagnetic interaction, the measured magnetization curves
below 7 K are somehow suppressed and linearly increase in
magnetic fields above 20 kOe instead of saturating. No steps
in the measured magnetization curves up to the magnetic
field of 70 kOe in the hysteresis loops were detected at tem-
perature of 2 K and higher.
with
six
MnIJII)
and
two
MnIJIII)
ions
is
. We used μeffIJII) = 5.9 μB
for MnIJII) (S = J = 5/2) ions and μeffIJIII) = 5.0 μB for MnIJIII) (S =
J = 2) ions.31 The measured average magnetic moment per
Mn ion at 300 K is 5.2 μB, appreciably less than the expected
value of 5.7 μB. With decreasing temperature, the average ef-
fective magnetic moment became even smaller (3.7 μB at 2
K), indicating a weak antiferromagnetic interaction between
Mn ions in the molecule. The strength of this interaction can
be estimated by applying a Curie–Weiss fit for the high-
temperature susceptibility data: χ = C/(T − θ). The result for T
>100 K is shown as a full line in Fig. 4, with parameters C =
27.8 emu K mol−1 and θ = −13.6 K. The rather small and neg-
ative value of the Curie–Weiss temperature θ is in agreement
with the proposed weak antiferromagnetic interaction.
The most dominant exchange interactions in the molecule
are those of oxygen-bridged MnIJII)–MnIJII) and MnIJII)–MnIJIII)
ions. Typically these exchange interactions are weak and anti-
ferromagnetic,23a,31 as obtained for our system, too. A similar
temperature-dependent susceptibility and a weak antiferro-
magnetic interaction was detected also in two structurally
very similar compounds with six MnIJII) and two MnIJII) ions
per molecule and the same bridges.23 Finally, we measured
isothermal magnetization at low temperatures and ac suscep-
tibility, in search for typical single-molecule magnet
The real, χ′, and imaginary (out-of-phase), χ″, parts of the
ac susceptibility were measured between 2 K and 30 K in an
alternating magnetic field with an amplitude of 3 Oe and
eleven different frequencies ranging from 11 Hz up to 2311
Hz. For clarity we show in Fig. 6 susceptibility for 11 Hz,
1111 Hz and 2111 Hz only. The χ′ for all frequencies practi-
cally superimpose and the susceptibility is the same as that
measured in a static magnetic field. The absence of any dis-
tinguishable signal in the imaginary part χ″ that would usu-
ally accompany slow magnetization relaxation processes can
be understand as a confirmation of no single-molecule mag-
netism. This is different from results shown in the
literature,23b where, in addition to antiferromagnetic, a weak
ferromagnetic interaction between oxygen-bridged six Mnii
and ten Mniii ions has been detected. Wide hysteresis loops
have been measured below 1 K.23 The absence of such a hys-
teresis loop in our sample may be because of the following
factors: a) the MIJH) curves being collected at too high temper-
atures (due to the experimental limitations, we were not able
to reach temperatures below 1.8 K), and (or) b) the influence
of ligands on the magnetic interaction, that does not provide
a weak ferromagnetic component. It has been demonstrated
that ligands in structurally-similar structures of oxygen-
Fig. 4 Magnetic susceptibility and effective magnetic moment (inset)
between 2 K and 300 K measured in a magnetic field of 1000 Oe. The
full green line is a Curie–Weiss fit.
Fig.
5 Isothermal magnetization curves. Full lines are fits with a
Brillouin function for S = J = 5/2.
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Powder X-ray diffraction (PXRD) data were collected on a
Philips X'Pert Pro MPD X-ray diffractometer with MoKα radia-
tion
equipped
with
an
X'Celerator
detector.
Thermogravimetric analyses (TGA) were performed on a
Netzsch STA 449C thermal analyzer from room temperature
to 800 °C under a nitrogen atmosphere, at a heating rate of
10 °C min−1. The diffuse reflectance spectrum was collected
using a UV-vis spectrophotometer (Evolution 220, ISA-220 ac-
cessory, Thermo Scientific) using a built-in 10 mm silicon
photodiode with a 60 mm Spectralon sphere.
Synthesis of [MnIII2MnII6O2IJPhCOO)10IJdmhmp)4IJH2O)2]
·4CH3CN (1)
Fig. 6 Real part and imaginary part (inset) of the ac susceptibility.
MnIJClO4)2·6H2O (181 mg, 0.5 mmol), benzoic acid (61 mg,
0.5 mmol) and Hdmhmp (63 mg, 0.5 mmol) were dissolved
in a mixture of 5 mL CH3CN–CH3OH (1 : 1) with 100 μL NEt3
to get a pale-yellow solution. This solution was filtered and
the filtrate was allowed to evaporate slowly in air at room
temperature. Complex 1 crystallized as brown crystals after
two days in a yield of 85% based on Hdmhmp. Anal. calc.
(found) for (C102H102Mn8N12O28): C, 51.40 (51.38); H, 4.31
(4.36); N, 7.05 (6.99)%. Selected IR bands (cm−1): 1603(m),
1562(m), 1540(m), 1491(w), 1463(w), 1394(s), 1265(w),
1103(m), 1078(m), 1046(m), 1025(m), 835(w), 790(w), 712(s),
675(m), 623(m), 603(m).
bridged manganese ions have an enormous impact on the
magnetic interaction between Mn ions.33
Solid-state UV-vis-NIR diffuse reflectance spectroscopy
The UV-vis-NIR spectrum for 1 was measured in the solid
state using the diffuse reflectance mode and is shown in
Fig. 7. The absorption at 272 nm has its origin in the π → π*
transition of the PhCO2 or dmhmp− ligands, and the shoul-
−
der at around 490 nm may originate from metal-to-ligand
charge transfer.34 The fine structure for the d–d band is not
observed, although both d4 MnIII and d5 MnII exist in 1.
X-ray crystallography
Experimental
Crystals of 1 quickly lost the solvents from the lattice once
they left the mother liquor. Therefore, a crystal was quickly
picked out from the mother liquor then transferred to a cryo-
genic environment for the collection of intensity data on a
Methods
All chemicals and solvents used in the syntheses were of ana-
lytical grade and used without further purification. IR spectra
were recorded on a PerkinElmer Spectrum Two in the fre-
quency range of 4000–400 cm−1. The elemental analyses (C,
H, N contents) were determined on a Vario EL III analyzer.
The variable-temperature magnetic susceptibilities were col-
lected on a Magnetic Property Measurement System (MPMS),
SQUID-VSM (superconducting quantum interference device-
vibrating sample magnetometer) (Quantum Design, USA).
Bruker APEX II CCD diffractometer (200(2) K) with
graphite-monochromated Cu Kα radiation source (λ
a
=
1.54178 Å). Cell refinement, data reduction and absorption
correction were carried out using the Bruker SAINT software
package.35 The intensities were extracted by the program
XPREP. The structures were solved with direct methods using
SHELXS, and least-squares refinement was done against Fo2bs
using routines from the SHELXTL software.36 In 1, the unit
cell contains a large region of disordered solvent water mole-
cules, which could not be modeled as discrete atomic sites,
and thus we employed PLATON/SQUEEZE to produce a set of
solvent-free diffraction intensities,37 which was used for fur-
ther refinement. Crystal data for 1 are given in Table 2. Se-
lected bond lengths and angles are listed in Table S1.†
Conclusions
In summary, a new mixed-valent Mn8 cluster constructed
from 3,5-dimethyl-1-(hydroxymethyl)-pyrazole and benzoic
acid has been successfully isolated, which shows a paired
−
[Mn4O3] defect cubanes core protected by ten PhCO2 and
four μ3-dmhmp− ligands. The HRESI-MS indicates that its
[MnIII2MnII6O2] core structure is not decomposed in solution,
and interesting ligand exchange between PhCOO− and
Fig. 7 Diffuse reflectance UV-visible-NIR spectrum of 1.
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Table 2 Crystal data for complex 1
Wernsdorfer, V. Nastopoulos, G. Christou and A. J.
Tasiopoulos, Inorg. Chem., 2009, 48, 5049; (d) S. Nayak,
L. M. C. Beltran, Y. Lan, R. Clérac, N. G. R. Hearns, W.
Wernsdorfer, C. E. Anson and A. K. Powell, Dalton Trans.,
2009, 1901; (e) Th. C. Stamatatos, K. A. Abboud, W.
Wernsdorfer and G. Christou, Angew. Chem., Int. Ed.,
2007, 46, 884.
Empirical formula
C94H90Mn8N8O28
Formula weight
Temperature/K
Crystal system
Space group
a/Å
b/Å
c/Å
α/°
β/°
2219.26
200(2)
Triclinic
¯
P1
14.0134(7)
14.8016(7)
15.2457(6)
105.689(5)
113.922(4)
103.178(5)
2570.0(2)
1
3 (a) G. Christou, D. Gatteschi, D. N. Hendrickson and R.
Sessoli, MRS Bull., 2000, 25, 66; (b) G. Aromi and E. K.
Brechin, Struct. Bonding, 2006, 122, 1; (c) R. Bircher, G.
Chaboussant, C. Dobe, H. U. Gudel, S. T. Ochsenbein, A.
Sieber and O. Waldmann, Adv. Funct. Mater., 2006, 16, 209;
(d) R. Sessoli, H. L. Tsai, A. R. Schake, S. Y. Wang, J. B.
Vincent, K. Folting, D. Gatteschi, G. Christou and D. N.
Hendrickson, J. Am. Chem. Soc., 1993, 115, 1804; (e) R.
Sessoli, D. Gatteschi, A. Caneschi and M. A. Novak, Nature,
1993, 365, 141.
γ/°
Volume/Å3
Z
ρcalc mg mm−3
1.434
8.374
μ/mm1
FIJ000)
1134.0
2θ range for data
collection
Index ranges
6.72 to 120°
−15 ≤ h ≤ 15, −16 ≤ k ≤ 16, −17 ≤ l ≤
17
4 Y. Umena, K. Kawakami, J. R. Shen and N. Kamiya, Nature,
2011, 473, 55.
Reflections collected
Independent reflections
Data/parameters
18 731
7272ijRIJint) = 0.0873]
7272/626
5 (a) B. Kok, B. Forbrush and M. McGloin, Photochem.
Photobiol., 1970, 11, 457; (b) C. Zhang, C. Chen, H. Dong,
J. R. Shen, H. Dau and J. Zhao, Science, 2015, 348, 690; (c) K.
Jin, J. Park, J. Lee, K. D. Yang, G. K. Pradhan, U. Sim, D.
Jeong, H. L. Jang, S. Park, D. Kim, N. E. Sung, S. H. Kim, S.
Han and K. T. Nam, J. Am. Chem. Soc., 2014, 136, 7435; (d)
X. B. Han, Y. G. Li, Z. M. Zhang, H. Q. Tan, Y. Lu and E. B.
Wang, J. Am. Chem. Soc., 2015, 137, 5486; (e) A. K. Poulsen,
A. Rompel and C. J. McKenzie, Angew. Chem., Int. Ed.,
2005, 44, 6916; ( f ) S. Mukhopadhyay, S. K. Mandal, S.
Bhaduri and W. H. Armstrong, Chem. Rev., 2004, 104, 3981.
6 (a) C. J. Milios, M. Manoli, G. Rajaraman, A. Mishra, L. E.
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Final R indexes [I ≦ 2σ(I)] R1 = 0.0534, wR2 = 0.1121
Final R indexes [all data]
Largest diff. peak/hole/e
Å−3
R1 = 0.0935, wR2 = 0.1249
0.57/−0.37
dmhmp− was evidenced. Both the characteristic oxidation
process of MnII → MnIII and reduction process of MnIII
→
MnII were identified in cyclic voltammetry measurement.
Weak intramolecular antiferromagnetic interactions between
the MnII and MnIII ions were found in the Mn8 cluster.
Acknowledgements
This work was supported by the NSFC (Grant No. 21201110,
21227001 and 21571115), Young Scholars Program of Shan-
dong University (2015WLJH24), The Fundamental Research
Funds of Shandong University (2015JC045), and Slovenian Re-
search Agency (ARRS), Program Number P2-0348.
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