Family of mixed 3d-4f dimeric 14-metallacrown-5 compounds: Syntheses, structures, and magnetic properties

Article abstract of DOI:10.1021/ic3025952

An isomorphous family of mixed 3d-4f dodenuclear aggregates, {[Mn ^III₈Ln₄(Clshi)₈(OAc) ₆(μ₃-OCH₃)₂(μ₃-O) ₂(CH₃OH)₁₂(H₂O)₂] ·4CH₃OH·xH₂O)} (where Ln = Eu^III (1), Gd^III (2), Tb^III (3), and Dy^III (4); ClshiH₃ = 5-chlorosalicylhydroxamic acid; x = 5 for 1 and 3; x = 6 for 2; x = 2 for 4), were synthesized and characterized. They were obtained from the reaction of ClshiH₃ with Mn(OAc)₂·4H ₂O and Ln(NO₃)₃·6H₂O. These isomorphous mixed 3d-4f compounds represent a family of novel structures with lanthanide ions in the metallacrown (MC) ring. Each dodecanuclear aggregate contains two offset stacked 14-MC-5 units with M-N-O-M-N-O-Ln-O-N-M-O-N-M connectivity to capture one Ln^III ion in the core of each MC. Two 14-MC-5 units are connected through O ions with four Mn ions and six O atoms arranged in a double Mn₄O₆ cubane. Magnetic measurement indicates that antiferromagnetic interactions are present between the metal ions. The Dy^III analogue with high anisotropy and large spin shows slow magnetization relaxation at a direct-current field of 2 kOe.

Full text of DOI:10.1021/ic3025952

Article
pubs.acs.org/IC
Family of Mixed 3d−4f Dimeric 14-Metallacrown‑5 Compounds:
Syntheses, Structures, and Magnetic Properties
Fan Cao,†,‡ Suna Wang,†,‡ Dacheng Li,† Suyuan Zeng,† Meiju Niu,† You Song,*,‡ and Jianmin Dou*,†
†Shandong Provincial Key Laboratory of Chemical Energy Storage and Novel Cell Technology, School of Chemistry and Chemical
Engineering, Liaocheng University, 252059 Liaocheng, People’s Republic of China
‡State Key Laboratory of Coordination Chemistry, Nanjing National Laboratory of Microstructures, School of Chemistry and
Chemical Engineering, Nanjing University, 210093 Nanjing, People’s Republic of China
S
* Supporting Information
ABSTRACT: An isomorphous family of mixed 3d−4f dodenuclear aggregates, {[MnIII8Ln4(Clshi)8(OAc)6(μ3-OCH3)2-
(μ3-O)2(CH3OH)12(H2O)2]·4CH3OH·xH2O)} (where Ln = EuIII (1), GdIII (2), TbIII (3), and DyIII (4); ClshiH3
=
5-chlorosalicylhydroxamic acid; x = 5 for 1 and 3; x = 6 for 2; x = 2 for 4), were synthesized and characterized. They were obtained
from the reaction of ClshiH3 with Mn(OAc)2·4H2O and Ln(NO3)3·6H2O. These isomorphous mixed 3d−4f compounds represent a
family of novel structures with lanthanide ions in the metallacrown (MC) ring. Each dodecanuclear aggregate contains two offset
stacked 14-MC-5 units with M−N−O−M−N−O−Ln−O−N−M−O−N−M connectivity to capture one LnIII ion in the core of
each MC. Two 14-MC-5 units are connected through O ions with four Mn ions and six O atoms arranged in a double Mn4O6
cubane. Magnetic measurement indicates that antiferromagnetic interactions are present between the metal ions. The DyIII analogue
with high anisotropy and large spin shows slow magnetization relaxation at a direct-current field of 2 kOe.
parameter (D) could be obtained. That is why MCs could
potentially behave as SMMs.
INTRODUCTION
■
Metallacrowns (MCs), a kind of metallamacrocycle compound
similar to organic crowns with O or N atoms replaced by metal
atoms, were reported in 1989, with the first structures represented
by [VO(shi)(MeOH)]3 (9-MC-3) and Mn(OAc)2[Mn4(shi)4-
(DMF)6]·2DMF (12-MC-4; DMF = N,N-dimethylformamide
and shi = salicylhydroxamic acid).1 Since then, MCs have received
much attention not only for their diverse architectures but also for
their potential applications in host−guest recognition and
bioactivities.2,3 Considerable efforts have been devoted to
magnetic studies of these kinds of compounds since the initial
discovery of single-molecule magnets (SMM) in 1993.4−7 The
SMM behavior is strongly related with large ground-state spin [S]
and large easy-axis anisotropy [negative zero-field-splitting (ZFS)
parameter, D]. Structurally, MCs typically possess a large number
of metal ions to provide a large spin. The configuration easily
enforces a planar arrangement of the metal ions by controlling the
topology of the compounds through alignment of single-ion
magnetoanisotropy, and therefore a large molecular ZFS
The selection of suitable metal ions is important to SMMs. A
high-spin MnIII ion has four unpaired electrons per ion (S = 2)
and large anisotropy because of its Jahn−Teller (JT) axis, which
has been the most popular in the construction of SMMs. With
both large spin and considerable single-ion anisotropy, a single
anisotropic magnetic LnIII ion in an axial crystal-field environ-
ment could provide sufficient conditions to establish a thermal
barrier for reversal of the magnetization.8 A combination of
these two kinds of metal ions in one compound may lead to
SMM behavior. Up to now, manganese−lanthanide (Mn−Ln)
SMMs have also garnered considerable attention, such as Mn−
Gd2, Mn2−Gd, Mn2−Ln2, Mn2−Dy2, Mn2−Ln3, Mn2−Ln4,
Mn3−Ln, Mn4−Ln2, Mn4−Ln3, Mn4−Ln4, Mn4−Gd4, Mn4−
Dy6, Mn5−Ln4, Mn5−Tb6, Mn5−Ln8, Mn6−Ce2, Mn6−Ln2,
Mn6−Ln4, Mn6−Dy6, Mn8−Ce, Mn9−Dy8, Mn10−Ln2,
Received: November 27, 2012
© XXXX American Chemical Society
A
dx.doi.org/10.1021/ic3025952 | Inorg. Chem. XXXX, XXX, XXX−XXX

Inorganic Chemistry
Article
Table 1. Crystallographic Data and Structure Refinement for Compounds 1−4
1
2
3
4
formula
Mr
C86H126Cl8Eu4Mn8N8O63
3610.91
C86H128Cl8Gd4Mn8N8O64
3650.08
C86H126Cl8 Tb4Mn8N8O63
3638.75
C86H124Cl8Dy4Mn8N8O62
3635.05
cryst size [mm3]
0.26 × 0.23 × 0.15
black
0.32 × 0.29 × 0.18
black
0.36 × 0.34 × 0.33
black
0.36 × 0.35 × 0.33
black
color
cryst syst
space group
T [K]
triclinic
triclinic
triclinic
triclinic
P1
̅
298(2)
P1
̅
298(2)
P1
̅
298(2)
P1
̅
298(2)
a [Å]
12.9509(11)
12.9702(12)
20.4300(18)
3322.7(5)
1
12.9985(11)
13.0134(12)
20.455(2)
3350.8(5)
1
12.9208(7)
12.9568(8)
20.2851(11)
3283.0(3)
1
12.9550(11)
12.9788(12)
20.3847(16)
3317.7(5)
1
b [Å]
c [Å]
V [Å3]
Z
ρcalcd [mg m−3
λ [Å]
]
1.745
1.803
1.843
1.721
0.71073
2.838
0.71073
2.927
0.71073
3.122
0.71073
3.202
μ [mm−1
]
F(000)
1718
1792
1796
1680
reflns collected/unique reflns
Rint
GOF on F2
16111/11506
0.0334
16867/11638
0.0413
22006/11576
0.0435
16482/11425
0.0259
1.063
1.047
1.052
1.144
R1 [I > 2σ(I)], wR2 (all data)
0.0475, 0.1402
0.0530, 0.1612
0.0525, 0.1428
0.0546, 0.1777
Mn11−Ln4, Mn11−Gd2, Mn12−Gd2, Mn12−Dy6, Mn12−Ce22,
Mn18−Dy, and Mn21−Dy.9−20
double Mn4O6 cubane arrangement, forming a novel dimeric
14-MC-5 structure. Magnetic measurement indicates that
antiferromagnetic interactions are dominant between the metal
ions. The DyIII analogue with high anisotropy and large spin
shows slow magnetization relaxation at a direct-current (dc) field
of 2 kOe. The different structures and magnetic properties be-
tween these dimeric 14-MC-5 compounds and similar monomer
14-MC-5 compounds were discussed in detail.
In 2010, Pecoraro et al. first incorporated a LnIII ion into the
MC ring and reported mixed 3d−4f Mn4−Ln2-14-MC-5
compounds, namely, [Ln2Mn4O(OH)(OAc)(NO3)2(shi)4]·
3C3H7NO·7C5H5N·H2O (Ln = Y, Gd, Tb, Dy, and Ho),
among which Tb-14-MC-5, Dy-14-MC-5, and Ho-14-MC-5
showed slow magnetic relaxation, with Dy-14-MC-5 demon-
strating a blocking temperature above 2 K.10d The authors
reported that uniaxial anisotropy was a critical factor to
maximize the overall anisotropy of a compound and the utility
of the planar MC structure aligning the easy axes parallel to
each other should be extended in order to create an SMM. The
DyIII analogue showed the highest blocking temperature,
suggesting that DyIII may have the highest “blend” of spin
and anisotropy needed for effective SMMs. It was also
confirmed by a planar Mn-12-MC-4 involving a MnII ion in
the center cavity of the MC ring.21 Otherwise, geometric
control of the metal center in the cavity of the MC ring has
proven to be an efficient path to maximizing the single-ion
magnetoanisotropy in the Mn5-12-MC-4 compound.
EXPERIMENTAL SECTION
■
Materials and Syntheses. All reagents were obtained from
commercial sources and were used as received, without further
purification. All reactions were carried out under aerobic conditions.
5-Chlorosalicylhydroxamic acid (ClshiH3) was prepared by the
condensation of 5-chlorosalicylic acid and hydroxylamine in a 1:1 molar
ratio in water according to a modified procedure reported previously.24
Synthesis of [MnIII8EuIII4(Clshi)8(OAc)6(μ3-OCH3)2(μ3-O)2-
(CH3OH)12(H2O)2]·4CH3OH·5H2O (1). Eu(NO3)3·6H2O (0.338 g,
1 mmol) was added to a stirred solution of Mn(OAc)2·4H2O (0.980 g,
4 mmol) and ClshiH3 (0.752 g, 4 mmol) in MeOH (25 mL), and the
pH was adjusted to 8 with [(C4H9)4N]OH. The solution immediately
became green and was stirred at room temperature. After 6 h, the color
changed to dark green, and then the solution was filtered and left
undisturbed at room temperature. The black block single crystals,
suitable for X-ray diffraction analysis, were obtained after 2 weeks.
These crystals were collected by filtration, washed with cold MeOH,
and dried in air. Yield: 13 mg (27%, based on the ligand). Elem anal.
Calcd for C86H126Cl8Eu4Mn8N8O63: C, 28.58; H, 3.52; N, 3.10.
Found: C, 28.19; H, 3.61; N, 3.22. IR (KBr, cm−1): 3234(vs), 2867(s),
2687(w), 1231(m), 1235(w), 1879(m), 1235(s), 1679(w), 1145(m),
1689(m), 925(m), 748(m), 669(m), 612(m), 578(m).
We have also focused on MC chemistry and recently
reported a novel 9-MC-3 and 15-MC-6 onset stacked MC
SMM, [Mn9O4(Me-sao)6(MeO)3(O2CMe)3(OH)(MeOH)2]·
2.5DMF (Me-saoH2 = 2-hydroxyphenylethanone oxime).22,23
Herein, we report the syntheses and characterization of {Mn4−
Ln2}2 dimeric 14-MC-5 compounds assembled from 5-
chlorosalicylhydroxamic acid, {[MnIII8Ln4(Clshi)8(OAc)6(μ3-
OCH3)2(μ3-O)2(CH3OH)12(H2O)2]·4CH3OH·xH2O)}
(where Ln = EuIII (1), GdIII (2), TbIII (3), and DyIII (4); x = 5
for 1 and 3; x = 6 for 2; x = 2 for 4). The isomorphous
compounds represent a family of novel mixed 3d−4f
compounds with lanthanide in the MC ring. Each structure
consists of two offset stacked monomer 14-MC-5 units with
M−N−O−M−N−O−Ln−O−N−M−O−N−M connectivity
to capture one LnIII ion in the core of each MC, similar to
the reported examples by Pecoraro’s group. Two μ3-CH3O−
groups and two η2-O atoms of different 5-Clshi3− ligands bridge
two 14-MC-5 units with four Mn ions and six O atoms in a
Synthesis of [MnIII8GdIII4(Clshi)8(OAc)6(μ3-OCH3)2(μ3-
O)2(CH3OH)12(H2O)2]·4CH3OH·6H2O (2). This compound was
obtained as brown block crystals according to the procedure for 1,
using Gd(NO3)3·6H2O (0.343 g, 1 mmol) in place of Eu(NO3)3·
6H2O. Yield: 17 mg (31%, based on the ligand). Elem anal. Calcd for
C86H128Cl8Gd4Mn8N8O64: C, 28.30; H, 3.53; N, 3.07. Found: C,
27.97; H, 3.64; N, 3.37. IR (KBr, cm−1): 2969(w), 1654(s), 1765(s),
1876(m), 1453(m), 1786(m), 1564(s), 1254(m), 1687(m), 1235(w),
968(w), 856(w), 778(m), 668(m), 594(m), 457(w), 423(m).
Synthesis of [MnIII8TbIII4(Clshi)8(OAc)6(μ3-OCH3)2(μ3-
O)2(CH3OH)12(H2O)2]·4CH3OH·5H2O (3). This compound was
obtained as brown block crystals according to the procedure for 1,
B
dx.doi.org/10.1021/ic3025952 | Inorg. Chem. XXXX, XXX, XXX−XXX

Inorganic Chemistry
Article
a
Table 2. Selected Bond Distances (Å) and Angles (deg) for Compounds 1−4
1
3
Eu1−O3
Eu1−O6
Eu1−O13
Eu1−O24
Eu2−O5
Eu2−O6
Eu2−O15
Eu2−O20
Mn1−O1
Mn1−O13
2.467(5)
2.367(5)
2.279(5)
2.484(6)
2.305(6)
2.350(5)
2.411(6)
2.442(7)
1.849(5)
1.872(5)
Mn1−O14
Mn1−O26
Mn1−N1
Mn2−O2
Mn2−O3
Mn2−O4
Mn2−O18
Mn2−O23
Mn2−N2
1.967(5)
2.197(6)
1.956(7)
1.912(5)
1.931(5)
1.857(6)
2.325(6)
2.241(7)
1.923(7)
Tb1−O3
Tb1−O6
Tb1−O31
Tb1−O39
Tb2−O5
Tb2−O6
Tb2−O14
Tb2−O18
Mn1−O1
Mn1−O13
2.456(6)
2.363(6)
2.434(7)
2.255(5)
2.304(6)
2.326(6)
2.384(6)
2.407(7)
1.859(6)
2.529(6)
Mn1−O22
Mn1−O39
Mn1−N1
Mn2−O2
Mn2−O3
Mn2−O4
Mn2−O17
Mn2−O25
Mn2−N2
2.195(6)
1.866(6)
1.957(7)
1.912(6)
1.929(5)
1.865(6)
2.322(6)
2.250(6)
1.926(7)
Eu1−O6−Eu2
Eu1−O13−Mn1
Eu1−O3−Mn2
Eu1−O12−Mn3
111.8(2)
129.2(2)
123.8(2)
123.7(2)
Eu1−O13−Mn4
Mn1−O13−Mn4
Mn1−O14−Mn4A
Mn4−O14−Mn4A
130.8(2)
98.3(2)
Tb1−O6−Tb2
Tb2−O39−Mn1
Tb2−O3−Mn2
Tb2−O12−Mn3
111.8(2)
130.4(3)
123.8(3)
123.8(2)
Tb2−O39−Mn4
Mn1−O39−Mn4
Mn1−O13−Mn4A
Mn4−O13−Mn4A
130.5(3)
97.8(2)
105.7(2)
102.3(2)
105.2(2)
102.4(2)
2
4
Gd1−O3
Gd1−O6
Gd1−O13
Gd1−O24
Gd2−O5
Gd2−O6
Gd2−O15
Gd2−O20
Mn1−O1
Mn1−O13
2.458(6)
2.363(6)
2.301(6)
2.456(8)
2.308(7)
2.340(6)
2.405(7)
2.431(9)
1.856(6)
1.851(6)
Mn1−O14
Mn1−O27
Mn1−N1
Mn2−O2
Mn2−O3
Mn2−O4
Mn2−O18
Mn2−O25
Mn2−N2
1.975(6)
2.208(7)
1.965(8)
1.919(7)
1.935(6)
1.862(7)
2.319(8)
2.254(8)
1.933(8)
Dy1−O3
Dy1−O6
Dy1−O18
Dy1−O31
Dy2−O5
Dy2−O6
Dy2−O15
Dy2−O29
Mn1−O1
Mn1−O24
2.450(6)
2.353(6)
2.425(7)
2.260(6)
2.280(7)
2.310(7)
2.375(9)
2.353(7)
1.872(6)
2.208(7)
Mn1−O28
Mn1−O31
Mn1−N1
Mn2−O2
Mn2−O3
Mn2−O4
Mn2−O16
Mn2−O17
Mn2−N2
1.965(6)
1.864(6)
1.965(7)
1.917(7)
1.942(6)
1.874(7)
2.324(7)
2.246(8)
1.923(8)
Gd1−O6−Gd2
Gd2−O13−Mn1
Gd2−O3−Mn2
Gd2−O12−Mn3
112.2(3)
128.8(3)
123.7(3)
123.8(3)
Gd2−O13−Mn4
Mn1−O14−Mn4
Mn1−O14−Mn4A
Mn4−O14−Mn4A
130.1(3)
91.2(2)
Dy1−O6−Dy2
Dy1−O31−Mn1
Dy2−O3−Mn2
Dy2−O12−Mn3
112.3(3)
129.3(3)
123.8(3)
124.2(3)
Dy2−O31−Mn4
Mn1−O31−Mn4
Mn1−O28−Mn4A
Mn4−O28−Mn4A
130.7(3)
90.7(2)
105.7(3)
102.5(3)
106.1(3)
101.8(2)
a
Symmetry code: A, −x + 2, −y + 1, −z; B, −x + 1, −y + 1, −z for 1; A, −x + 1, −y + 1, −z + 1; B, −x + 1, −y + 2, −z + 1 for 2; A, −x + 1, −y + 2,
−z + 1; B, −x, −y, −z + 1 for 3; −x + 1, −y, −z + 2 for 4.
using Tb(NO3)3·6H2O (0.345 g, 1 mmol) in place of Eu(NO3)3·
6H2O. Yield: 13 mg (28%, based on the ligand). Elem anal. Calcd for
C86H126Cl8Tb4Mn8N8O63: C, 28.39; H, 3.49; N, 3.08. Found: C,
28.18; H, 3.65; N, 3.19. IR (KBr, cm−1): 3212(s), 2978(m), 2098(w),
1521(w), 1875(vs), 1215(m), 1789(m), 1231(s), 1687(w), 1687(w),
954(m), 898(m), 718(s), 654(w), 423(w), 475(s).
maps and then treated isotropically as riding. Further details for
crystallography and selected bond parameters are listed in Tables 1
and 2, respectively.
Physical Measurements. Elemental analyses for carbon, hydro-
gen, and nitrogen were carried out with a Perkin-Elmer 240C
elemental analyzer. IR spectra were recorded on a Bruker VECTOR22
FT-IR spectrometer using a KBr pellet technique. Magnetic measure-
ments on crystalline samples were carried out at an applied field of
2 kOe on a Quantum Design MPMS-XL7 superconducting quantum
interference device (SQUID) magnetometer working in the temper-
ature range of 300−1.8 K. The molar magnetic susceptibilities were
corrected for diamagnetism estimated from Pascal’s tables and for the
sample holder by previous calibration.
Synthesis of [MnIII8DyIII4(Clshi)8(OAc)6(μ3-OCH3)2(μ3-
O)2(CH3OH)12(H2O)2]·4CH3OH·4H2O (4). This compound was
obtained as brown block crystals according to the procedure for 1,
using Dy(NO3)3·6H2O (0.349 g, 1 mmol) in place of Eu(NO3)3·
6H2O. Yield: 17 mg (32%, based on the ligand). Elem anal. Calcd for
C86H124Cl8Dy4Mn8N8O62: C, 28.42; H, 3.43; N, 3.08. Found: C,
28.19; H, 3.63; N, 3.26. IR (KBr, cm−1): 3354(vs), 2785(w), 2135(w),
1786(s), 1868(s), 1535(s), 1789(s), 1453(s), 1657(w), 1546(s),
925(m), 868(m), 786(m), 684(m), 668(m), 438(m).
RESULTS AND DISCUSSION
■
X-ray Crystallography. Single-crystal X-ray diffraction data for
compounds 1−4 were collected on a Bruker Smart CCD area-detector
diffractometer with Mo Kα radiation (λ = 0.71073 Å) by ω-scan mode
operating at room temperature. The program SAINT was used for
integration of the diffraction profiles, and semiempirical absorption
corrections were applied using SADABS.25,26 All of the structures were
solved by direct methods using the SHELXS program of the
SHELXTL package and refined by full-matrix least-squares methods
with SHELXL.27 Metal ions were located from the E maps, and the
other non-H atoms were located in successive difference Fourier
syntheses and refined with anisotropic thermal parameters on F2.
Generally, C-bound H atoms were determined theoretically and
refined with isotropic thermal parameters riding on their parents. H
atoms of water and MeOH were first located by difference Fourier E
Syntheses. Among the various strategies used in the
synthesis of Mn 4f compounds, those using small-nuclearity
species with [Mn3O]6+/7+ or [Mn4O2]8+ cores proved to be
fruitful to construct high (≥4)-nuclearity Mn−Ln com-
pounds.9,13,16−18 In previous documents, a series of Ln6Mn6-
or Mn-12-MC-4 compounds of salicylhydroxamic acid (shi)
were synthesized in MeOH.28 Also with the same ligand,
Pecoraro and co-workers obtained Mn4Ln2 compounds with
similar 14-MC-5 structure incorporating rare-earth metals into
Mn-MC systems. The reactions were carried out in DMF
through simple manganese and lanthanide salts.10d In this work,
however, we obtained the titled compounds by the reaction of
C
dx.doi.org/10.1021/ic3025952 | Inorg. Chem. XXXX, XXX, XXX−XXX

Inorganic Chemistry
Article
Mn(OAc)2, ClshiH3, and lanthanide nitrate salts in a 4:4:1
molar ratio in MeOH at room temperature. Apparently, the
solvents play an important role in the formation of such
compounds.
Additionally, two other important factors may lead to the
resulting product. First, a substituted shi (ClshiH3) was
employed in our reaction, in which the electronegativity of
the Cl atom may influence the electron properties of the ligand
and further the assembly of the structure. Second, tetrabuty-
lammonium hydroxide was added in the reaction mixture to
adjust the pH value of the solution. The organic base may
facilitate deprotonation of the ligand and air oxidation of the
manganese(II) starting material.29
torsion angles are 179.4(4)° and 176.6(4)° for Mn1−N1−O3−
Mn2 and Mn3−O12−N4−Mn4 and the Mn−N−O−Dy torsion
angles are −168.7(4)° and +173.4(4)° for Mn2−N2−O6−Dy2 and
Mn3−N3−O9−Dy2, respectively.
The oxidation states of Mn ions were deduced from the
meric parameters and charge-balance consideration, which was
further confirmed by bond valence sum (BVS) calculations (see
the Supporting Information, Table S2). All MnIII ions exhibit
distorted six-coordinate octahedral geometry, and the JT and
apical axes are approximately perpendicular to the MC plane.
Two kinds of coordination environments of Mn ions are
observed. For Mn1 and Mn4, the equatorial plane is composed
of a six-membered iminophenolate ring from one 5-Clshi3−
ligand, one μ3-O2− ion, and one μ3-CH3O− ion. The apical
positions are occupied by two O atoms from the carboxylate
group and another μ3-CH3O− ion. For Mn2 and Mn3, however,
the equatorial plane consists of one six-membered iminophe-
nolate ring and one five-numbered hydroximate ring from
different 5-Clshi3− ligands. The axial positions are occupied by
MeOH molecules.
Description of the Crystal Structures. Single-crystal
X-ray structure analysis reveals that all isomorphous compounds
crystallize in the space group P1, presenting two offset stacked
̅
symmetry-related 14-MC-5 units. [Mn4Dy2]2 (4) is described
representatively. As shown in Figure 1, each 14-MC-5 unit
The encapsulated Dy1 is surrounded by eight O atoms, four
of which in the equatorial plane are from hydroximate of discrete
5-Clshi3− ligands that bridges Mn2, Mn3, and Dy2, while the fifth
is from μ3-O that bridges Mn1 and Mn4. The axial positions are
occupied by one acetate group and one aqua molecule. Another
lanthanide ion Dy2 on the plane of the molecule is eight-
coordinate and bound to two five-membered hydroximate rings,
one acetate group, and two MeOH molecules.
Similar monomeric 14-MC-5 compounds were reported very
recently by Pecoraro et al. that represent the first M−N−O MC
to incorporate both μ-O and μ-OH in the ring and the first MC
with the inclusion of one metal that differs from the other ring
metals.10d Interestingly, in our case, these two 14-MC-5 units
are joined together by two μ3-CH3O− groups and two η2-O of
different 5-Clshi3− ligands, forming a unique dimeric structure
with two 14-MC-5 in offset stacked mode in which a double
Mn4O6 cuboidal arrangement is formed. The Mn−O bond
distances are in the range of 1.965−2.386 Å, consistent with
similar bonds in manganese compounds (1.8−2.3 Å).29,30 Such
a specific bridging mode may provide an opportunity to obtain
interesting magnetic properties different from those of
structures containing ordinary MCs.
Upon careful inspection of the structure, the dimeric molecules
in the compounds could further assemble into a one-dimensional
network via intramolecular π···π stacking interaction (see the
Supporting Information, Figure S1). Within each molecule,
neighboring 14-MC-5 planes are connected via face-to-face π···π
stacking interactions.
Figure 1. Overall molecular structure and two offset stacked 14-MC-5
cores of 4, respectively. H atoms have been omitted for clarity.
Symmetry code: A, −x + 1, −y, −z + 2.
Magnetic Properties. dc Magnetic Properties. dc SQUID
magnetometry for compounds 1−4 was conducted at an
applied field of 2000 Oe and in the temperature range of 1.8−
300 K. The χMT versus T plots are shown in Figure 2. χM is the
molar magnetic susceptibility per [MnIII4LnIII2]2 dimeric unit.
The values of χMT at room temperature were all slightly lower
than the expected value with the presence of eight MnIII and
four LnIII uncoupled ions, as listed in Table 3. In most of MnIII-
based compounds, the room-temperature effective magnetic
moment is lower than the theoretical value, assuming g = 2. As
possesses four MnIII ions, two DyIII ions, four deprotonated
5-Clshi3− ligands, one μ3-O ion, one μ3-CH3OH molecule, and
two coordinated carboxylate groups as well as four coordinated
water molecules. Phenolate O, carbonyl O, hydroximate O, and
imine N atoms of the 5-Clshi3− ligand are all involved in the
coordination. In the equatorial plane, four 5-Clshi3− ligands
adopt μ4:η2:η1:η2:η1 and μ3:η1:η1:η2:η1 fashion types to connect
four MnIII ions and one DyIII ion to form a new 14-MC-5 cyclic
unit with connectivity of [Mn−N−O−Mn−N−O−Ln−O−
N−Mn−O−N−Mn−O−]. Mn1, Mn2, Dy1, Mn3, and Mn4
are bridged through M−N−O connectivity in order, while Mn1
and Mn4 are connected by one μ3-O2− ion, one μ3-CH3O− ion, and
one syn−syn carboxylate group of acetate. The Mn−N−O−Mn
a matter of fact, the Lande
́
factor of MnIII is lower than 2.0. On
the other hand, antiferromagnetic coupling between metal ions
also leads to a smaller value than the theoretical magnetic
moment. All compounds in this manuscript exhibit anti-
ferromangetic coupling between two [Mn4Ln2] units, leading to
D
dx.doi.org/10.1021/ic3025952 | Inorg. Chem. XXXX, XXX, XXX−XXX

Inorganic Chemistry
Article
between the [Mn4]2 units and LnIII ions as well as the single-ion
magnetoanisotropy of LnIII ions. Because of the presence of a
large orbital contribution from the 4f ions and the complexity of
the magnetic coupling interactions within these compounds,
fitting the data to obtain the coupling constants is not feasible.
As shown in Figure 3, the dc magnetization data of the
compounds were carried out in the ranges of magnetic field from 1
to 7 T and temperature from 10 to 1.8 K, respectively. These
compounds exhibit similar behavior with an increase at low field
and then a linear increase without clear saturation at 7 T with values
of 10.78 μB for 1, 39.64 μB for 2, 30.00 μB for 3, and 29.36 μB for 4.
As for the reduced magnetization (M/NμB − H/T) curves, the
nonsuperimposition properties of all of the compounds suggest the
presence of magnetic anisotropy and the lack of a well-defined
ground state.
Alternating-Current (ac) Magnetic Properties. To probe
the dynamics of magnetization relaxation, ac susceptibility
measurements were performed in a zero applied dc field with a
5.0 Oe ac field oscillating at frequencies in the range of 1−1500
Hz and in the temperature range of 1.8−10.0 K. Except for 4,
other compounds do not exhibit any out-of-phase ac signals
(see the Supporting Information, Figure S3).
Figure 2. χMT versus T plots for 1−4 at 2000 Oe.
Table 3. Expected and Measured χT Values (cm3 K mol−1)
for Dimeric [Mn4Ln2]2 and Monomeric [Mn4Ln2] at 300 K
[Mn4Ln2]2 in this
work
[Mn4Ln2] in ref 10d
The in-phase χ′MT signal of 4 showed a frequency-dependent
decrease at T < 4 K, indicating the presence of slow magnetization
relaxation and thus probably SMM behavior. The out-of-phase
χ″M signals showed weak frequency dependence (Figure 4a,b).
The maxima of these signals, however, were not observed above
1.8 K, the lowest limit of the instrument. Consequently, the
effective energy barrier (Ueff) and the magnetization relaxation
time (τ) could not be determined. Owing to the extremely low
blocking temperature, the hysteresis experiments could not also be
performed to definitively characterize the compound as SMM.
It should be noted that when the dc field increased to 2 kOe,
the frequency-dependent properties increased and significant
maxima of the peaks were observed (Figure 4c,d). The Cole−
Cole plot of the in-phase (χ′M) versus out-of-phase (χ″M) signal
of the ac magnetic susceptibility exhibits two interesting
relaxation phases at a dc field of 2 kOe (Figure 5). The
relaxation time for each process can be extracted by fitting the
data to two relaxation processes using the sum of two modified
Debye functions:32
trivalent
lanthanide
ion
theoretical
value for a
single ion
expected measured expected measured
value
value
value
value
Eu (1)
Gd (2)
Tb (3)
Dy (4)
1.50
7.88
30.00
55.52
71.28
80.68
27.74
54.95
62.83
71.72
27.76
35.64
40.34
25
27
36
11.82
14.17
a slight decrease of the magnetic moment. So, these two effects
make the χMT values lower in all compounds. Similar
phenomena were also observed in the monomeric structures.
Upon lowering of the temperature, these values decreased
steadily. From 50 K, the values decreased rapidly and reached
0.86 [for [Mn4Eu2]2 (1)], 16.19 [for [Mn4Gd2]2 (2)], 31.48
[for [Mn4Tb2]2 (3)], and 41.23 cm3 K mol−1 (for 4) at 1.8 K,
respectively. Such behavior indicates that antiferromagnetic
interaction between the metal centers dominates the magnetic
properties of 1−4.
Similar to other Mn-4f compounds, the magnetic behavior of
this family of compounds also combines the MnIII−MnIII,
MnIII−LnIII, and LnIII−LnIII interactions in addition to the
intrinsic magnetic properties of the LnIII ions. For compound 1
containing the EuIII ion, we may try investigating the magnetic
interaction mode between metal ions, while for other
compounds, it is difficult to define.
Δχ
Δχ
2
1
χac(ω) = χS,tot
ω = 2πv
+
+
,
2
1 + (iωτ1)1−α
1 + (iωτ2)1−α
1
where χS,tot = χS1 + χS2 represents the sum of the adiabatic
susceptibilities of the two relaxing species; Δχi is the difference
between the adiabatic susceptibility (χSi) and the isothermal
susceptibility (χTi) of each magnetic phase. The experimental
χac(ω) curves between 1.8 and 3.0 K can be nicely simulated by
applying the equation and depicted as χ′(ω) and χ″(ω). The
simulations of dynamical susceptibility ranging from 1.8 to 3.0 K
are shown in Figures 5 and S2 in the Supporting Information,
respectively. The fitting parameters obtained are summarized in
Table S1 in the Supporting Information.
From the Cole−Cole plot, a conclusion can be drawn that
compound 4 displays closely spaced relaxation pathways under
an applied dc field. A two-step relaxation process illustrates that
two relaxation phases could be separated into two parts: a high-
frequency domain at frequencies from 10 to 1500 Hz and a
low-frequency domain at frequencies from 1 to 6.8 Hz. Thus,
the parameters α and τ are obtained by Debye simulation
7
The EuIII ion has a F0 ground state with a 4f6 configuration
(7F0, S = 3, L = 3, J = 0). At low temperature, only the
nonmagnetic ground level is occupied with the infinitesimal
excited states mixing into 7F0.31 Therefore, the low-temperature
magnetic properties of compound 1 are only dominated by the
exchange interaction between MnIII ions. This means that the
EuIII ions can be considered as the diamagnetic centers at low
temperatures. On the basis of the low-temperature χMT values
and the extrapolation at 0 K, which is approaching zero, the
ground-state spin of 1 can be determined to be S = 0. Thus, we
can draw a conclusion that the antiferromagnetic behavior of 1 is
attributed to the combination of MnIII−MnIII interaction within
and between two [Mn4] units. For other compounds that also
possess antiferromagnetic [Mn4]2 units, the nonzero ground-
state spins may result from the contribution of uncanceled spins
E
dx.doi.org/10.1021/ic3025952 | Inorg. Chem. XXXX, XXX, XXX−XXX

Inorganic Chemistry
Article
Figure 3. Plot of the field-dependent magnetization and reduced magnetization (insets) of 1−4 at the indicated applied fields and temperatures. The
solid lines are guides for the eyes.
quantifying the width of the τ distribution and the relaxation
time, respectively. The parameter α1 increases but α2 decreases
with heating, and the relaxation time τ1 is much larger than τ2.
Both of the differences of parameters α and τ indicate two
different relaxation mechanisms in the spin reversal of the
compound. On the basis of the above analysis, the right
incomplete part corresponding to a low-frequency domain
could be assigned to slower relaxation (SR) dynamics with
parameters α1 and τ1 and the left semicircles corresponding to a
high-frequency one are the faster relaxation (FR) dynamics
with parameters α2 and τ2. Long et al. have recently reported
the observation of a secondary slow relaxation process for the
field-induced SMM.33 They calculated this by fitting the data of
each individual relaxation domain using a generalized Debye
model. Similar results were observed in which the α parameters
changed with opposite tendencies while the temperature changed
and the relaxation times τ were different between the FR and SR
domains. Because of the complexity of the relaxation mechanism
of lanthanide ions and the differences between single lanthanide
ion magnetic behavior and that of the transition-metal-cluster
SMMs, further characterization of this system will require
measurements at lower frequencies and temperatures to
investigate the multiple relaxation pathways in detail.34
to remove the asymmetry of the overall Cole−Cole curve.
Similar field-induced SMM or SIM behavior was investigated in
the presence of nonzero dc fields. The origin of the field-induced
relaxation behavior could be attributed to suppressed fast
quantum tunneling of magnetization by applied dc fields. Similar
phenomena have also been observed in recent compounds.35
In a previous manuscript of Pecoraro, the authors reported the
isostructural Y, Gd, Tb, Dy, and Ho monomeric 14-MC-5. In
five structures, the latter three examples displayed slow magnetic
relaxation, while the former two examples did not and the Dy
compound exhibited the highest blocking temperature. In our
dimeric 14-MC-5, however, only the Dy example showed
magnetic dependence upon the frequencies at nonzero field.
That is, optimal behavior was observed in the DyIII compound,
and similar phenomena have been found in other series of
compounds.36 This may be explained by the intrinsic properties of
trivalent LnIII ions. The Kramers ion DyIII could always maintain
the doubly degenerate ground state under the magnetic field in
most of coordination environment. The non-Kramers ion, TbIII,
however, needs a strictly axial crystal-field symmetry. Additionally,
the EuIII ion has a J = 0 ground state, while the GdIII ion is
isotropic.
Compared to other similar monomeric Mn4Dy2-14-MC-5
compounds exhibiting strong frequency dependence at all
frequencies in a zero dc field, the SMM property of the
[Mn8Dy2]2 compound in this work is apparently weakened.
Two major reasons should be taken into account to interpret
According to Long’s work, magnetic measurements indicated
that, as the dc field is increased, the asymmetry in the Cole−Cole
plot disappears and a smooth semicircular arc is observed. The
increasing dc field could eliminate one of the relaxation processes
F
dx.doi.org/10.1021/ic3025952 | Inorg. Chem. XXXX, XXX, XXX−XXX

Inorganic Chemistry
Article
Figure 4. Plots of the in-phase (χ′M) and out-of-phase (χ″M) signals for 4 in ac susceptibility studies versus T in a 5.0 Oe field with a zero dc field (a)
compared to an applied dc field of 2 kOe (b). The solid lines are guides for the eyes.
Pecoraro and co-workers had reported that the planarity of
the MC ring was very important to preclude the likelihood of
anisotropy vectors of each single metal ion canceling each other
to decrease the integrated anisotropy of the whole molecule.
The important geometry parameters of the monomeric 14-MC-5
and dimeric 14-MC-5 compounds in this work are listed in
Figure S4 in the Supporting Information. One can see that the
metal···metal distances between the metal ions within these
structures were similar. A side view of the two MC rings,
however, showed different planarity. In the monomeric 14-MC-5
structure, the DyIII ion within the MC ring (Dy1) and the
encapsulated (Dy2) DyIII ion are 1.734 and 0.300 Å above the
MC plane, respectively. In the dimeric structure of this work,
these DyIII ions are 0.113 and 0.402 Å below and above the MC
plane, respectively. Additionally, the coordination geometries
around the DyIII ions in both structures are different because one
acetate bridged both of the DyIII ions in the monomer, which
Figure 5. Plots of the in-phase (χ′M) versus out-of-phase (χ″M) signals
for 4 in ac susceptibility studies in a 5.0 Oe field under an applied dc
field of 2000 Oe. The solid lines are guides for the eyes.
could be related to the differences of the deviation between the
DyIII ions and the MC plane.
The skeleton structure of the dimer showed a higher
planarity than that of the monomer. The planar MC ring always
shows antiferromagnetic coupling between metal ions within
the ring, so the ground-state spin is low.37 In contrast, a
nonplanar MC ring provides ferromagnetic coupling between
metal ions, and the compound will have a higher ground-state
spin. According to Ueff = |D|S2, the energy barrier of the dimer
the weak magnetic properties of the dimer compared to the
monomer. One is the probable antiferromagnetic interactions
within the planar MC rings. The second is the antiferromag-
netic coupling interactions at the junction of two MC rings,
which are related to the MnIII−O(R)−MnIII angles.
G
dx.doi.org/10.1021/ic3025952 | Inorg. Chem. XXXX, XXX, XXX−XXX

Inorganic Chemistry
Article
should be lower than that of the monomer, further leading to
frequency-dependent signals of 4 in this work in lower
temperature. So, the signals can be observed under the
required applied field. Thus, we could conclude that the
planarity of the MC ring is the origin of different magnetic
properties between the monomer and dimer.
AUTHOR INFORMATION
Corresponding Authors
*E-mail: yousong@nju.edu.cn.
*E-mail: jmdou@lcu.edu.cn.
Notes
■
The authors declare no competing financial interest.
Second, antiferromagnetic coupling could usually quench the
SMM properties because of the reduced ground-state spin. In 4,
two 14-MC-5 units were connected by two μ3-CH3O− groups
and two η2-O atoms of different 5-Clshi3− ligands with four Mn
ions and six O atoms in a double Mn4O6 cubane arrangement.
Generally, MnIII−O(R)−MnIII angles smaller than about 102°
tend to favor ferromagnetic exchange interactions.38,39 In this
double cubane, the Mn−O−Mn angles are in the range of
101.82−106.11°, indicating antiferromagnetic interaction within
the MnIII ions. Considering a similar analysis investigated by
Christou and co-workers with respect to offset stacked 9-MC-3,
one can see that the MnIII−O(R)−MnIII angles in the junction
of two MC rings in these compounds are all smaller than 102°,
resulting in ferromagnetic interactions between the MC rings.40 It
is remarkable that π−π intramolecular interaction between the two
offset stacked MC rings could explain the different MnIII−O(R)−
MnIII angles between the monomer and dimer.
From these experiments, one can see the importance of the
choice of LnIII on the SMM properties. Powell, Pecoraro, and
other groups have also performed systematic investigations on
the family of isomorphous compounds, showing that the slow
magnetic relaxation behavior of the compound depends on
both the spin and anisotropy components of LnIII.9−11 They
also reported that the DyIII ion may have the right “blend” of
spin and anisotropy needed for effective SMMs. In our case, the
DyIII analogue showed slow magnetization relaxation, con-
sistent with previous investigations; even the SMM properties
were decreased compared with monomeric 14-MC-5.
ACKNOWLEDGMENTS
■
We are thankful to the National Natural Science Foundation of
China (Grants 21271097 and 21141003) and Liaocheng
University for financial support. We are thankful to the
National Natural Science Foundation of China (Grants
21271097 and 21141003) for financial support.
REFERENCES
■
(1) (a) Pecoraro, V. L. Inorg. Chim. Acta 1989, 155, 171. (b) Lah, M.
S.; Pecoraro, V. L. J. Am. Chem. Soc. 1990, 11, 59.
(2) (a) Pecoraro, V. L.; Stemmler, A. J.; Gibney, B. R.; Wang, H.;
Kampf, J. W.; Barwinski, A. Prog. Inorg. Chem. 1997, 45, 83.
(b) Bodwin, J. J.; Cutland-Van Noord, A. D.; Malkani, G. R.;
Pecoraro, V. L. Coord. Chem. Rev. 2001, 216−217, 489. (c) Mezei, G.;
Zaleski, C. M.; Pecoraro, V. L. Chem. Rev. 2007, 107, 4933.
(3) (a) Zaleski, C. M.; Depperman, E. C.; Kampf, J. W.; Kirk, M. L.;
Pecoraro, V. L. Inorg. Chem. 2006, 45, 10022. (b) Zaleski, C. M.;
Kampf, J. W.; Mallah, T.; Kirk, M. L.; Pecoraro, V. L. Inorg. Chem.
2007, 46, 1954. (c) Xu, H. B.; Wang, B. W.; Pan, F.; Wang, Z. M.;
Gao, S. Angew. Chem., Int. Ed. 2007, 47, 7388.
(4) (a) Sessoli, R.; Gatteschi, D.; Novak, M. A. Nature 1993, 365,
141. (b) Sessoli, R.; Tsai, H.; Schake, A. R.; Wang, S.; Vincent, J. B.;
Folting, K.; Gatteschi, D.; Christou, G.; Hendrickson, D. N. J. Am.
Chem. Soc. 1993, 115, 1804.
(5) (a) Aromil, G.; Brechin, E. K. Struct. Bonding (Berlin) 2006, 122,
1. (b) Christou, G. Polyhedron 2005, 24, 2065. (c) Roubeau, O.;
́
Clerac, R. Eur. J. Inorg. Chem. 2008, 4325. (d) Tasiopoulos, A. J.;
Perlepes, S. P. Dalton Trans. 2008, 5537. (e) Bagai, R.; Christou, G.
Chem. Soc. Rev. 2009, 38, 1011. (f) Stamatatos, T. C.; Christou, G.
Inorg. Chem. 2009, 48, 3308.
CONCLUSION
■
(6) Dendrinou-Samara, C.; Alexiou, M.; Zaleski, C. M.; Kampf, J. W.;
Kirk, M. L.; Kessissoglou, D. P.; Pecoraro, V. L. Angew. Chem., Int. Ed.
2003, 42, 3763.
(7) Zaleski, C. M.; Depperman, E. C.; Dendrinou-Samara, C.;
Alexiou, M.; Kampf, J. W.; Kessissoglou, D. P.; Kirk, M. L.; Pecoraro,
V. L. J. Am. Chem. Soc. 2005, 127, 12862.
(8) (a) Aldamen, M. A.; Clemente-Juan, J. M.; Coronado, E.; Martí-
Gastaldo, C.; Gaita-Arino, A. J. Am. Chem. Soc. 2008, 130, 8874.
(b) Ishikawa, N.; Sugita, M.; Ishikawa, T.; Koshihara, S.-y.; Kaizu, Y. J.
Am. Chem. Soc. 2003, 125, 8694.
In summary, the use of ClshiH3 in reactions with manganese and
lanthanide salts results in the formation of a new family of 3d−4f
dodenuclear compounds with the lanthanide ions in the MC ring,
each containing two offset stacked 14-MC-5 units with M−N−O−
M−N−O−Ln−O−N−M−O−N−M connectivity. The magnetic
behavior of the family of compounds was discussed in detail
including the MnIII−MnIII, MnIII−LnIII, and LnIII−LnIII inter-
actions. MnIII−MnIII interaction within and between the units in all
compounds may be antiferromagnetic. The nonzero ground states
of compounds 2−4 are the result of uncanceled net spins between
the LnIII and MnIII ions. The DyIII analogue with high anisotropy
and large spin shows slow magnetization relaxation at a dc field of
2 kOe. The effect of the planarity of the MC, the choice of LnIII
ions, and the connectivity of the two MCs are discussed in detail.
(9) (a) Mereacre, V.; Lan, Y.; Clerac, R.; Ako, A. M.; Hewitt, I. J.;
Wernsdorfer, W.; Buth, G.; Anson, C. E.; Powell, A. K. Inorg. Chem.
2010, 49, 5293. (b) Ako, A. M.; Lan, Y. H.; Clerac, R.; Wernsdorfer,
́
W.; Hewitt, I. J.; Anson, C. E.; Mereacre, V.; Anson, C. E.; Powell, A.
K. Polyhedron 2009, 28, 1698. (c) Mishra, A.; Wernsdorfer, W.;
Parson, S.; Christou, G.; Brechin, E. K. Chem. Commun. 2005, 2086.
(d) Akhtar, M. N.; Zheng, Y. Z.; Lan, Y. H.; Mereacre, V.; Anson, C.
E.; Powell, A. K. Inorg. Chem. 2009, 48, 3502. (e) Lampropoulos, C.;
Stamatatos, T. C.; Abboud, K. A.; Christou, G. Inorg. Chem. 2009, 48,
429. (f) Prasad, T. K.; Rajasekharan, M. V.; Costes, J. P. Angew. Chem.,
Int. Ed. 2007, 46, 2851. (g) Guedes, G. P.; Soriano, S.; Mercante, L. A.;
Speziali, N. L.; Novak, M. A.; Andruh, M.; Vaz, M. G. F. Inorg. Chem.
2013, 52, 8309. (h) Chandrasekhar, V.; Bag, P.; Speldrich, M.; Leusen,
ASSOCIATED CONTENT
* Supporting Information
■
S
Experimental procedures, crystal structure data of 1−4,
crystallographic data for 1−4 in CIF format, and a table of
BVS calculations. This material is available free of charge via the
Internet at http://pubs.acs.org. Crystallographic data for
structural analysis of the compounds have also been deposited
with the Cambridge Crystallographic Data Centre, under
CCDC 850415−850418. Copies of this information may be
obtained free of charge from The Director, CCDC, 12 Union
Road, Cambridge CB2 1EZ, U.K. (http://www.ccdc.cam.ac.uk;
fax +44-1223-762911).
J.; Kogerler, P. Inorg. Chem. 2013, 52, 5035. (i) Feuersenger, J.;
̈
́
Prodius, D.; Mereacre, V.; Clerac, R.; Anson, C. E.; Powell, A. K. Inorg.
Chem. Commun. 2011, 14, 1851. (j) Chilton, N. F.; Langley, S. K.;
Moubaraki, B.; Murray, K. S. Chem. Commun. 2010, 46, 7787.
(10) (a) Karotsis, G.; Kennedy, S.; Teat, S. J.; Beavers, C. M.; Fowler,
D. A.; Morales, J. J.; Evangelisti, M.; Dalgarno, S. J.; Brechin, E. K. J.
Am. Chem. Soc. 2010, 132, 12983. (b) Mereacre, V.; Akhtar, M. N.;
H
dx.doi.org/10.1021/ic3025952 | Inorg. Chem. XXXX, XXX, XXX−XXX

Inorganic Chemistry
Article
Lan, Y. H.; Ako, A. M.; Cler
́
ac, R.; Anson, C. E.; Powell, A. K. Dalton
(30) (a) Sanudo, E. C.; Grillo, V. A.; Knapp, M. J.; Bollinger, J. C.;
Huffman, J. C.; Hendrickson, D. N.; Christou, G. Inorg. Chem. 2002,
41, 2441. (b) Ghachtouli, S. E.; Guillot, R.; Aukauloo, A.; Dorlet, P.;
̃
Trans. 2010, 39, 4918. (c) Shiga, T.; Hoshino, N.; Nakano, M.; Nojiri,
H.; Oshio, H. Inorg. Chim. Acta 2008, 361, 4113. (d) Boron, T. T., III;
Kampf, J. W.; Pecoraro, V. L. Inorg. Chem. 2010, 49, 9104. (e) Liu, C.
M.; Zhang, D. Q.; Zhu, D. B. Dalton Trans. 2010, 39, 11325. (f) Li, M.;
Ako, A. M.; Lan, Y.; Wernsdorfer, W.; Buth, G.; Anson, C. E.; Powell,
A. K.; Wang, Z.; Gao, S. Dalton Trans. 2010, 39, 3375. (g) Majeed, Z.;
Mondal, K. C.; Kostakis, G. E.; Lan, Y.; Anson, C. E.; Powell, A. K.
Dalton Trans. 2010, 39, 4740. (h) Karotsis, G.; Evangelisti, M.;
Dalgarno, S. J.; Brechin, E. K. Angew. Chem., Int. Ed. 2009, 48, 9928.
Anxolabeher
(c) Naiya, S.; Biswas, S.; Drew, M. G. B.; Gom
́
e-Mallart, E.; Costentin, C. Inorg. Chem. 2012, 51, 3603.
ez-García, C. J.; Ghosh,
́
A. Inorg. Chem. 2012, 51, 5332. (d) Stamatatos, T. C.; Luisi, B. S.;
Moulton, B.; Christou, G. Inorg. Chem. 2008, 47, 1134.
(31) Wan, Y. H.; Zhang, L. P.; Jin, L. P.; Gao, S.; Lu, S. Z. Inorg.
Chem. 2003, 42, 4985.
(32) Grahl, M.; Kotzler, J.; Sessler, I. J. Magn. Magn. Mater. 1990,
90−1, 187.
(33) Rinehart, J. D.; Meihaus, K. R.; Long, J. R. J. Am. Chem. Soc.
2010, 132, 7572.
(34) Ishikawa, N.; Sugita, M.; Ishikawa, T.; Koshihara, S.; Kaizu, Y. J.
Phys. Chem. B 2004, 108, 11265.
́
(11) (a) Mereacre, V.; Ako, M. A.; Clerac, R.; Wernsdorfer, W.;
Hewitt, I.; Anson, C. E.; Powell, A. K. Chem.Eur. J. 2008, 14, 3577.
(b) Shiga, T.; Onuki, T.; Matsumoto, T.; Nojiri, H.; Newton, G. N.;
Hoshino, N.; Oshio, H. Chem. Commun. 2009, 3568. (c) Ako, A. M.;
́
Mereacre, V.; Clerac, R.; Hewitt, I. J.; Lan, Y.; Buth, G.; Anson, C. E.;
Powell, A. K. Inorg. Chem. 2009, 48, 6713.
́
(35) (a) Li, D.; Parkin, S.; Wang, G.; Yee, G. T.; Clerac, R.;
Wernsdorfer, W.; Holmes, S. M. J. Am. Chem. Soc. 2006, 128, 4214.
(b) Bhunia, A.; Gamer, M. T.; Ungur, L.; Chibotaru, L. F.; Powell, A.
K.; Lan, Y.; Roesky, P. W.; Menges, F.; Riehn, C.; Niedner-
Schatteburg, G. Inorg. Chem. 2012, 51, 9589. (c) Liu, J. L.; Yuan,
K.; Leng, J. D.; Ungur, L.; Wernsdorfer, W.; Guo, F. S.; Chibotaru, L.
F.; Tong, M. L. Inorg. Chem. 2012, 51, 8538. (d) Vallejo, J.; Castro, I.;
Ruiz-García, R.; Cano, J.; Julve, M.; Lloret, F.; Munno, G. D.;
Wernsdorfer, W.; Pardo, E. J. Am. Chem. Soc. 2012, 134, 15704.
(e) Liu, S. J.; Zhao, J. P.; Song, W. C.; Han, S. D.; Liu, Z. Y.; Bu, X. H.
Inorg. Chem. 2013, 52, 2103.
(12) (a) Rigaux, G.; Inglis, R.; Morrison, S.; Prescimone, M.; Brechin,
E. K. Dalton Trans. 2011, 40, 4797. (b) Holyn
Jeon, I.; Wernsdorfer, W.; Cler
17, 9605. (c) Zaleski, C. M.; Kampf, J. W.; Mallah, T.; Kirk, M. L.;
Pecoraro, V. L. Inorg. Chem. 2007, 46, 1954. (d) Wang, M.; Yuan, D.
Q.; Ma, C. B.; Yuan, M. J.; Hu, M. Q.; Li, N.; Chen, H.; Chen, C. N.;
Liu, Q. T. Dalton Trans. 2010, 39, 7276.
̌
́ ́
ska, M.; Premuzic, D.;
́
ac, R.; Dehnen, S. Chem.Eur. J. 2011,
(13) Zaleski, C. M.; Depperman, E. C.; Kampf, J. W.; Kirk, M. L.;
Pecoraro, V. L. Angew. Chem., Int. Ed. 2004, 43, 3912.
(14) Mishra, A.; Tasiopoulos, A. J.; Wernsdorfer, W.; Moushi, E. E.;
Moulton, B.; Zaworotko, M. J.; Abboud, K. A.; Christou, G. Inorg.
Chem. 2008, 47, 4832.
(15) Langlry, S. K.; Moubaraki, B.; Murray, K. S. Dalton Trans. 2010,
39, 5066.
(16) Mereacre, V.; Prodius, D.; Ako, A. M.; Kaur, N.; Lipkowski, J.;
Simmons, C.; Dalal, N.; Geru, I.; Anson, C. E.; Powell, A. K.; Turta, C.
Polyhedron 2008, 27, 2459.
(36) Rinehart, J. D.; Long, J. R. Chem. Sci. 2011, 2, 2078.
(37) (a) Milios, C. J.; Piligkos, S.; Brechin, E. K. Dalton Trans. 2008,
1809. (b) Milios, C. J.; Vinslava, A.; Wood, P. A.; Parsons, S.;
Wernsdorfer, W.; Christou, G.; Perlepes, S. P.; Brechin, E. K. J. Am.
Chem. Soc. 2007, 129, 8. (c) Cano, J.; Cauchy, T.; Ruiz, E.; Milios, C.
J.; Stoumpos, C. C.; Stamatatos, T. C.; Perlepes, S. P.; Christou, G.;
Brechin, E. K. Dalton Trans. 2008, 234. (d) Milios, C. J.; Vinslava, A.;
Wernsdorfer, W.; Moggach, S.; Parsons, S.; Perlepes, S. P.; Christou,
G.; Brechin, E. K. J. Am. Chem. Soc. 2007, 129, 2754. (e) Yang, C. I.;
Cheng, K. H.; Hung, S. P.; Nakano, M.; Tsai, H. L. Polyhedron 2011,
30, 3272. (f) Yang, C. I.; Wernsdorfer, W.; Cheng, K. H.; Nakano, M.;
Lee, G. H.; Tsai, H. L. Inorg. Chem. 2008, 47, 10184.
(17) (a) Mishra, A.; Wernsdorfer, W.; Abboud, K.; Christou, G. J.
Am. Chem. Soc. 2004, 126, 15648. (b) Mereacre, V.; Ayuk, A. M.;
Cler
́ ́
ac, R.; Wernsdorfer, W.; Filoti, G.; Bartolome, J.; Anson, C. E.;
Powell, A. K. J. Am. Chem. Soc. 2007, 129, 9248.
́
(18) (a) Stamatatos, T. C.; Teat, S. J.; Wernsdorfer, W.; Christou, G.
Angew. Chem., Int. Ed. 2009, 48, 521. (b) Liu, J. L.; Guo, F. S.; Meng,
Z. S.; Zheng, Y. Z.; Leng, J. D.; Tong, M. L.; Ungur, L.; Chibotaru, L.
F.; Herouxc, K. J.; Hendrickson, D. N. Chem. Sci. 2011, 2, 1268.
(38) Miyasaka, H.; Clerac, R.; Mizushima, K.; Sugiura, K.; Yamashita,
M.; Wernsdorfer, W.; Coulon, C. Inorg. Chem. 2003, 42, 8203.
(39) Miyasaka, H.; Clerac, R.; Ishii, T.; Chang, H. C.; Kitagawa, S.;
Yamashita, M. J. Chem. Soc., Dalton Trans. 2002, 1528.
(40) (a) Yang, C. I.; Cheng, K. H.; Nakano, M.; Lee, G. H.; Tsai, H.
L. Polyhedron 2009, 28, 1842. (b) Yang, C. I.; Tsai, Y. J.; Hung, S. P.;
Tsai, H. L.; Nakano, M. Chem. Commun. 2010, 46, 5716. (c) Yang, C.
I.; Hung, S. P.; Lee, G. H.; Nakano, M.; Tsai, H. L. Inorg. Chem. 2010,
49, 7617.
́
(19) Ako, A. M.; Mereacre, V.; Clerac, R.; Wernsdorfer, W.; Hewitt,
I.; Anson, C. E.; Powell, A. K. Chem. Commun. 2009, 544.
(20) Papatriantafyllopoulou, C.; Wernsdorfer, W.; Abboud, K. A.;
Christou, G. Inorg. Chem. 2011, 50, 421.
(21) Zaleski, C. M.; Tricard, S.; Depperman, E. C.; Wernsdorfer, W.;
Mallah, T.; Kirk, M. L.; Pecoraro, V. L. Inorg. Chem. 2011, 50, 11348.
(22) (a) Dou, J. M.; Liu, M. L.; Li, D. C.; Wang, D. Q. Eur. J. Inorg.
Chem. 2006, 4866. (b) Chen, Y. T.; Dou, J. M.; Li, D. C.; Wang, S. N.;
Wang, D. Q. Inorg. Chem. Commun. 2010, 13, 167. (c) Zhao, X. J.; Li,
D. C.; Zhang, Q. F.; Wang, D. Q.; Dou, J. M. Inorg. Chem. Commun.
2010, 13, 346. (d) Shi, X. F.; Li, D. C.; Wang, S. N.; Zeng, S. Y.; Wang,
D. Q.; Dou, J. M. J. Solid State Chem. 2010, 183, 2144.
(23) Wang, S. N.; Kong, L. Q.; Yang, H.; He, Z. T.; Jiang, Z.; Li, D.
C.; Zeng, S. Y.; Niu, M. J.; Song, Y.; Dou, J. M. Inorg. Chem. 2011, 50,
2705.
(24) Chen, J. Q. Nonferrous Met. 1987, 3, 26.
(25) SAINT v5.0-6.01; Bruker Analytical X-ray Systems Inc.:
Madison, WI, 1998.
(26) Sheldrick, G. M. SADABS; University of Gottingen: Gottingen,
̈
̈
Germany.
(27) SHELXTL v5.1, Bruker Analytical X-ray Systems Inc.: Madison,
WI, 1999.
(28) Dendrinou-Samara, C.; Papadopoulos, A. N.; Malamatari, D. A.;
Tarushi, A.; Raptopoulou, C. P.; Terzis, A.; Samaras, E.; Kessissoglou,
D. P. J. Inorg. Biochem. 2005, 99, 864.
(29) Chen, H.; Ma, C. B.; Yan, D. Q.; Hu, M. Q.; Wen, H. M.; Liu,
Q. T.; Chen, C. N. Inorg. Chem. 2011, 50, 10342.
I
dx.doi.org/10.1021/ic3025952 | Inorg. Chem. XXXX, XXX, XXX−XXX