Two new lanthanide-radical complexes: Synthesis, structure, and magnetic properties

Article abstract of DOI:10.1080/00958972.2012.705281

Two new lanthanide-radical complexes, [Tb(hfac)₃(EtVNIT) ₂] (1) and [Dy(hfac)₃(EtVNIT)₂] (2) (EtVNIT=2-(4′-ethoxy-3′-methoxyphenyl)-4,4,5,5- tetramethylimidazoline-1-oxyl-3-oxide, hfac=1,1,1,5,5,5- hexafluoroace

Full text of DOI:10.1080/00958972.2012.705281

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Two new lanthanide–radical complexes:
synthesis, structure, and magnetic
properties
Chao Wang a , Ya-Li Wang a , Yue Ma a , Qing-Lun Wang a , Li-Cun
Li a & Dai-Zheng Liao a b c
a Department of Chemistry, Nankai University, Tianjin 300071, P.R.
China
b Tianjin Key Lab on Metal and Molecule-based Material Chemistry,
Nankai University, Tianjin 300071, P.R. China
c State Key Laboratory of Physical Chemistry of Solid Surface,
Xiamen University, Xiamen 361005, P.R. China
Accepted author version posted online: 21 Jun 2012.Version of
record first published: 06 Jul 2012.
To cite this article: Chao Wang , Ya-Li Wang , Yue Ma , Qing-Lun Wang , Li-Cun Li & Dai-Zheng Liao
(2012): Two new lanthanide–radical complexes: synthesis, structure, and magnetic properties,
Journal of Coordination Chemistry, 65:16, 2830-2838
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Journal of Coordination Chemistry
Vol. 65, No. 16, 20 August 2012, 2830–2838
Two new lanthanide–radical complexes: synthesis, structure,
and magnetic properties
CHAO WANGy, YA-LI WANGy, YUE MA*y, QING-LUN WANGy, LI-CUN LIy
and DAI-ZHENG LIAOyzx
yDepartment of Chemistry, Nankai University, Tianjin 300071, P.R. China
zTianjin Key Lab on Metal and Molecule-based Material Chemistry, Nankai University,
Tianjin 300071, P.R. China
xState Key Laboratory of Physical Chemistry of Solid Surface, Xiamen University,
Xiamen 361005, P.R. China
(Received 18 January 2012; in final form 7 May 2012)
Two new lanthanide–radical complexes, [Tb(hfac)3(EtVNIT)2] (1) and [Dy(hfac)3(EtVNIT)2]
(2) (EtVNIT ¼ 2-(40-ethoxy-30-methoxyphenyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide,
hfac ¼ 1,1,1,5,5,5-hexafluoroacetylacetonate), were synthesized; both display radical–
Ln(III)–radical (Ln¼Tb (1), Dy (2)) tri-spin structures. Magnetic studies reveal that
interactions between the lanthanide ions and radicals are ferromagnetic.
Keywords: Lanthanide ion; Nitronyl nitroxide radical; Crystal structure; Magnetic properties
1. Introduction
Since D. Gatteschi and co-workers discovered a family of rare-earth-based single-chain
magnets [1–4] using nitronyl nitroxide radical and lanthanide ion, lanthanide–radical
approach has been an effective method to obtain new single chain magnets [5–7] and
single molecule magnets [8–14]. Terbium(III) and dysprosium(III) are generally selected
as central ions [6–14] due to their large anisotropy. Constructing lanthanide–radical
complexes using terbium(III) and dysprosium(III) remains relevant to explore the
relationship between magnetic relaxation and coordination environments and the
nature of the magnetic interactions between lanthanide ion and the spin carriers. Thus,
we use 2-(40-ethoxy-30-methoxyphenyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide
(EtVNIT) as radical ligand to coordinate with terbium(III) and dysprosium(III).
EtVNIT chosen is very similar to the reported radical NITPhOEt [9], which constructs a
mononuclear SMM with Tb(III). Our purpose is to examine the influence of different
substituents of radical ligands (the adding of methoxy) on the magnetic properties of
SMMs. Unfortunately, neither of the two complexes has magnetic ordering even at low
temperature, but we evaluate the coupling between the central ion and the organic
radicals in this article.
*Corresponding author. Email: maynk@nankai.edu.cn
Journal of Coordination Chemistry
ISSN 0095-8972 print/ISSN 1029-0389 online ß 2012 Taylor & Francis
http://dx.doi.org/10.1080/00958972.2012.705281

Lanthanide–radical complexes
2831
Herein we reported the syntheses, crystal structures and magnetic properties of two
new lanthanide–radical complexes, [Tb(hfac)3(EtVNIT)2] (1) and [Dy(hfac)3(EtVNIT)2]
(2), showing radical–Ln(III)–radical (Ln¼Tb (1), Dy (2)) tri-spin structures.
2. Experimental
2.1. Materials and methods
All commercial chemicals were used as received. The solvents were purified by standard
methods. 2,3-Bis(hydroxylamino)-2,3-dimethylbutane was synthesized using the proce-
dure described by Ullman [15]. Ln(hfac)3 ꢀ 2H2O (Ln¼Tb, Dy, hfac ¼ 1,1,1,5,5,5-
hexafluoroacetylacetonate) was synthesized according to the literature [5]. Elemental
analyses for C, H, and N were carried out on a Perkin-Elmer elemental analyzer (model
240). Variable temperature magnetic susceptibilities were measured on a SQUID
MPMS XL-7 magnetometer from 2.0 K to 300 K at a magnetic field of 1000 Oe using
polycrystalline samples. Alternating-current susceptibilities of 1 were measured under
zero dc field at 1250 Hz from 2.0 to 20 K, while 2 was measured under 1000 Oe dc field
at 1400 Hz from 2.0 to 20 K. Diamagnetic corrections were estimated from Pascal’s
constants for all constituent atoms.
2.2. Synthesis of the radical EtVNIT
EtVNIT is synthesized according to the literature [15], but slightly modified as follows:
2,3-bis(hydroxylamino)-2,3-dimethylbutane (2.96 g, 20.0 mmol) and 4-ethoxy-3-meth-
oxybenzaldehyde (3.60 g, 20.0 mmol) were dissolved in 100 mL anhydrous methanol.
This mixture was heated to reflux for 12 h, and then cooled to room temperature and
stirred for 24 h. The slurry was filtered and washed with 5 mL cold methanol twice.
Then the white powder was suspended in 150 mL CH2Cl2, cooled to 0ꢁC, and then
150 mL water containing NaIO4 (6.0 g, 28.1 mmol) was added to this suspension. The
resulting mixture turned dark blue immediately and was stirred vigorously for 10 min at
0ꢁC. Finally, the dark blue layer was collected and dried over anhydrous MgSO4
overnight. After filtration to remove inorganic salts, the CH2Cl2 solution was
evaporated to dryness and the residue was purified by column chromatography on
silica gel (hexane : acetone ¼ 3 : 1 as eluent). Yield: 4.59 g (74.7%). Elemental Anal.
Calcd for C16H23N2O4 (307.36) (%): C, 62.52; H, 7.54; N, 9.11. Found (%): C, 62.12;
H, 7.79; N, 9.30.
2.3. Preparation of the lanthanide–radical complexes [Tb(hfac)3(EtVNIT)2] (1) and
[Dy(hfac)3(EtVNIT)2] (2)
[Tb(hfac)3(EtVNIT)2] (1): 80.8 mg (0.1 mmol) of Tb(hfac)3 ꢀ 2H2O was mixed with
25 mL n-heptane and this transparent solution was refluxed for 2 h. The resulting
solution was cooled to 70ꢁC, to which 30.7 mg (0.1 mmol) of EtVNIT and subsequently
10 mL of CH2Cl2 was added under stirring. After stirring for an additional hour, the
final dark violet-blue solution was allowed to cool, filtered and kept at 4ꢁC for

2832
C. Wang et al.
one week. When the solution became colorless, dark blue block crystals were formed
suitable for X-ray analysis. Yield: 27 mg (19% based on rare-earth element). Elemental
Anal. Calcd for C47H49F18N4O14Tb (1394.81) (%): C, 40.47; H, 3.54; N, 4.02. Found
(%): C, 40.31; H, 3.63; N, 4.09.
[Dy(hfac)3(EtVNIT)2] (2): Complex 2 was synthesized in similar manner, using
Dy(hfac)3 ꢀ 2H2O instead of Tb(hfac)3 ꢀ 2H2O. Yield: 29 mg (21%). Elemental Anal.
Calcd for C47H49F18N4O14Dy (1398.38) (%): C, 40.37; H, 3.53; N, 4.01. Found (%):
C, 40.48; H, 3.51; N, 3.94.
2.4. X-ray structure determination
Data were collected at 113(2) K on a Rigaku MM-007 single-crystal diffractometer
equipped with
a CCD area detector with graphite-monochromated Mo-Ka
˚
(ꢀ ¼ 0.71070 A). A summary of crystallographic data is given in table 1. Empirical
absorption corrections by semi-empirical from equivalents were carried out. The
structure was solved with SHELX [16, 17] and refined by full-matrix least squares based
on F2 with anisotropic thermal parameters for the non-hydrogen atoms. Hydrogen
atoms were located theoretically and refined isotropically. The selected bond lengths
and angles are listed in tables 2 and 3 for 1 and 2, respectively.
Table 1. Summary of crystal structure parameters for 1 and 2.
1
2
Empirical formula
Formula weight
Crystal system
Space group
C47H49F18N4O14Tb
1394.84
Monoclinic
C2/c
C47DyH49F18N4O14
1400.42
Monoclinic
C2/c
ꢁ
˚
Unit cell dimensions (A, )
a
b
c
21.7277(6)
11.7635(3)
22.8341(6)
92.581(2)
5830.3(3), 8
1.589
1.333
21.712(5)
11.688(3)
22.748(5)
92.273(3)
5768(2), 8
1.613
ꢁ
Volume (A ), Z
3
˚
Calculated density (Mg mꢂ3
)
Absorption coefficient (mmꢂ1
F(000)
)
1.417
2804
2792
ꢂ range (ꢁ)
Limiting indices
2.4823–28.9877
ꢂ25 ꢃ h ꢃ 25;
ꢂ14 ꢃ k ꢃ 9;
ꢂ10 ꢃ l ꢃ 27
10,463/5185
0.999
1.792–27.879
ꢂ25 ꢃ h ꢃ 24;
ꢂ13 ꢃ k ꢃ 13;
ꢂ26 ꢃ l ꢃ 7
19,407/5134
0.998
Reflections collected/unique
Completeness to ꢂ
Max. and min. transmission
Goodness-of-fit on F 2
Final R indices [I 4 2ꢃ(I)]
0.7213/0.6176
1.067
R1 ¼ 0.0306
wR2 ¼ 0.0351
R1 ¼ 0.0768
wR2 ¼ 0.0781
0.7457/0.6759
1.060
R1 ¼ 0.0261
wR2 ¼ 0.0269
R1 ¼ 0.0683
wR2 ¼ 0.0687
R indices (all data)

Lanthanide–radical complexes
2833
ꢁ
˚
Table 2. Selected bond lengths (A) and angles ( ) for 1.
O(1)–Tb(1)
O(3)–Tb(1)
N(1)–O(4)
2.409(2)
2.3885(19)
1.310(3)
O(2)–Tb(1)
O(4)–Tb(1)
N(2)–O(5)
2.3405(19)
2.344(2)
1.270(4)
N(1)–O(4)–Tb(1)
O(2)–Tb(1)–O(4)#1
O(2)–Tb(1)–O(3)#1
O(2)–Tb(1)–O(3)
O(2)–Tb(1)–O(1)
O(3)–Tb(1)–O(1)
O(4)–Tb(1)–O(1)#1
O(1)–Tb(1)–O(1)#1
133.67(17)
95.64(7)
147.50(7)
75.05(7)
72.83(7)
129.05(7)
72.32(7)
71.92(10)
O(2)–Tb(1)–O(4)
O(4)–Tb(1)–O(4)#1
O(4)–Tb(1)–O(3)#1
O(4)–Tb(1)–O(3)
O(4)–Tb(1)–O(1)
O(2)–Tb(1)–O(1)#1
O(3)–Tb(1)–O(1)#1
97.44(7)
143.45(10)
72.70(7)
77.99(7)
144.23(7)
72.98(7)
132.42(7)
Symmetry transformations used to generate equivalent atoms: #1: ꢂ x, y, ꢂz þ 1/2.
ꢁ
˚
Table 3. Selected bond lengths (A) and angles ( ) for 2.
Dy(1)–O(1)
Dy(1)–O(3)
N(1)–O(6)
2.3263(17)
2.3751(17)
1.314(3)
Dy(1)–O(2)
Dy(1)–O(6)
N(2)–O(7)
2.3972(17)
2.3301(16)
1.270(3)
N(1)–O(6)–Dy(1)
O(1)–Dy(1)–O(6)
O(6)–Dy(1)–O(3)
O(6)–Dy(1)–O(3)#1
O(1)–Dy(1)–O(2)
O(3)–Dy(1)–O(2)
O(6)–Dy(1)–O(2)#1
O(2)–Dy(1)–O(2)#1
133.66(14)
96.27(6)
72.29(6)
78.36(6)
73.30(6)
128.59(6)
144.17(6)
71.66(8)
O(1)–Dy(1)–O(6)#1
O(1)–Dy(1)–O(3)
O(1)–Dy(1)–O(3)#1
O(3)–Dy(1)–O(3)#1
O(6)–Dy(1)–O(2)
O(1)–Dy(1)–O(2)#1
O(3)–Dy(1)–O(2)#1
O(6)#1–Dy(1)–O(6)
96.69(6)
74.65(6)
147.27(6)
72.97(8)
72.51(6)
72.91(6)
132.84(6)
143.32(8)
Symmetry transformations used to generate equivalent atoms: #1: ꢂ x, y, ꢂz þ 1/2.
3. Results and discussion
3.1. Synthesis and crystal structures of 1 and 2
We followed syntheses of reported [Tb(hfac)3(NITPhOEt)2] [6], resulting in similar
tri-spin molecules instead of the 1-D chain structures. We have repeated this experiment
many times and measured the cell parameters, confirming that the tri-spin structures are
more stable under these experimental conditions. Indeed, the molar ratio could explain
the low yields of the reactions.
As shown in figure 1, the single-crystal X-ray analysis revealed that 1 is a tri-spin
system consisting of one Tb(hfac)3 and two EtVNIT molecules, the central Tb(III) is
eight-coordinate by six oxygen atoms from three hfac units with Tb–O bond lengths of
˚
2.341–2.409 A and two oxygen atoms from two radical molecules with Tb–O(4) bond
˚
length of 2.344 A, the coordination polyhedron can be described as a distorted
dodecahedron with triangular faces in D2d symmetry. The EtVNIT molecules are
˚
monodentate to Tb(III) through one N–O with N(1)–O(4) length of 1.310 A, while the
˚
uncoordinated N(2)–O(5) bond length is 1.270 A. As shown in figure 2, the shortest
˚
distance between uncoordinated oxygen atoms from radical units is 4.042 A, while in 2,
˚
the shortest distance is 4.059 A. The X-ray analysis showed that these two complexes
are isomorphous with replacement of the central ion causing little variation of crystal
parameters, bond lengths, and bond angles.

2834
C. Wang et al.
Figure 1. Molecular structure of 1 (left) and 2 (right) showing the coordination geometry of these tri-spin
complexes. All hydrogen atoms and disordered fluorines are omitted for clarity.
3.2. Magnetic properties
The temperature dependence of the magnetic susceptibilities, ꢄMT versus T plots for 1
and 2, is shown in figure 3. For 1, ꢄMT at room temperature is 13.40 cm3 K molꢂ1
,
which is a little higher than one uncoupled Tb(III) in the 7F6 ground state
(ꢄMT ¼ 11.81 cm3 K molꢂ1
)
and two EtVNIT molecules (S ¼ 1/2, ꢄMT ¼
0.38 cm3 K molꢂ1). The ꢄMT value increases smoothly and reaches a maximum at
35 K with a value of 14.07 cm3 K molꢂ1. Below 35 K, ꢄMT begins to descend and
sharply reaches a minimum of 12.14 cm3 K molꢂ1 at 3.0 K. For 2, at room temperature,
ꢄMT is 15.79 cm3 K molꢂ1, somewhat higher than the expected value of uncoupled
system of a Dy(III) (6H15/2, g ¼ 4/3, ꢄMT ¼ 14.18 cm3 K molꢂ1) and two EtVNIT
molecules (S ¼ 1/2, ꢄMT ¼ 0.375 cm3 K molꢂ1). On cooling, ꢄMT increases gradually
and reaches a maximum of 19.51 cm3 K molꢂ1 and then sharply reaches a minimum of
15.52 cm3 K molꢂ1
.
For these two complexes, there exist three kinds of magnetic interactions: (i) the
coupling between lanthanide and the directly bonded radical, (ii) the interaction
between two terminal radicals through the central lanthanide, and (iii) intermolecular
interactions between the radicals due to short contacts highlighted in figure 2. However,
because of the large anisotropy of terbium(III) and dysprosium(III), there are no
available strict analytical expressions of magnetic susceptibility for these complexes.
Therefore, to give a rough estimation of the magnetic interactions in these tri-spin
molecules, we take 1 as an example and assume that the total magnetic susceptibilities
ꢄ can be calculated as a sum of an isolated Tb(III) and two uncoupled EtVNIT
molecules (equation (1)), where all symbols have their usual meanings.
Ng2Rꢁ2
ꢄ ¼ 2ꢄR þ ꢄTb
¼
þ ꢄTb
:
ð1Þ
2kT
The Tb(III) has a 7F6 ground state (J ¼ 6) and may exhibit a splitting of the mj
2
^
ˆ
energy levels (H ¼ DJZ) in an axial crystal field. Thus, ꢄTb can be described by the
expression (equation (2)) previously derived by Kahwa [18]. In this expression, D1 is the

Lanthanide–radical complexes
2835
Figure 2. Packing arrangements of 1 (upper) and 2 (lower); these figures show that the shortest distances
˚
between uncoordinated oxygen atoms of the radical unit are 4.042 A (in 1) and 4.059 A (in 2). Hydrogen
˚
atoms and disordered fluorines are omitted for clarity.

2836
C. Wang et al.
20
19
18
14.0
13.5
13.0
12.5
12.0
complex 1
complex 2
17
16
15
0
50 100 150 200 250 300
0
50 100 150 200 250 300
T /K
T /K
Figure 3. The temperature dependence of magnetic susceptibilities in the form of ꢄM and ꢄMT vs. T plots for
1 and 2.
zero-field-splitting parameter:
(
)
2
3
ꢀꢂ36D
ꢁ
ꢀꢂ25D
ꢁ
ꢀꢂ16D
ꢁ
ꢀꢂ9D
ꢁ
1
1
1
1
36 exp
þ 25 exp
þ 16 exp
þ 9 exp
kT
kT
ꢁ
kT
kT
ꢀꢂ4D
ꢁ
ꢀꢂD
6
6
6
6
4
7
7
7
7
5
1
1
2Ng21ꢁ2
þ4 exp
2 exp
þ exp
kT
kT
ꢀꢂ25D
(
)
ꢄTb
¼
:
ð2Þ
ꢀꢂ36D
ꢁ
ꢁ
ꢀꢂ16D
ꢁ
ꢀꢂ9D
ꢁ
kT
1
1
1
1
þ 2 exp
þ 2 exp
þ 2 exp
kT
kT
kT
kT
ꢀꢂ4D
ꢁ
ꢀꢂD
ꢁ
1
1
þ2 exp
þ 2 exp
þ 1
kT
kT
The molecular field approximation (zJ01) has been introduced to roughly evaluate the
interactions between spin carriers and magnetic susceptibilities ꢄ1 can be calculated as
ꢂ
ꢃꢂ1
2zJ01
Ng21ꢁ2
ꢄ1 ¼ ꢄ 1 ꢂ
ꢀ ꢄ
:
ð3Þ
For 2, the magnetic susceptibilities ꢄ2 can be calculated as for 1 [19–21]. The
equations should be written as
2zJ02
Ng22ꢁ2
ꢄ2 ¼ ꢄð1 ꢂ
ꢀ ꢄÞꢂ1
,
Ng2Rꢁ2
ꢄ ¼ 2ꢄR þ ꢄDy
¼
þ ꢄDy
,
2kT
(
2
)
ꢀꢂ225D
ꢁ
ꢀꢂ169D
ꢁ
ꢀꢂ121D
ꢁ
ꢀꢂ81D
ꢁ
3
2
2
2
2
225 exp
þ 169 exp
þ 121 exp
þ 9 exp
þ 81 exp
4kT
4kT
ꢀꢂ25D
4kT
ꢁ
4kT
ꢀꢂ49D
ꢁ
ꢁ
ꢀꢂ9D
ꢀꢂD
ꢁ
6
7
7
7
7
5
2
2
2
2
4kT
Ng22ꢁ2
6
þ 49 exp
þ 25 exp
þ exp
4kT
4kT
4kT
6
6
4
(
)
ꢄDy
¼
:
ꢀꢂ225D
ꢁ
ꢀꢂ169D
ꢁ
ꢀꢂ121D
ꢁ
ꢀꢂ81D
ꢁ
ꢀꢂ49D
ꢁ
2
2
2
2
2
4kT
exp
þ exp
þ exp
þ exp
þ exp
4kT
4kT
4kT
ꢀꢂD
4kT
4kT
ꢀꢂ25D
ꢁ
ꢀꢂ9D
ꢁ
ꢁ
2
2
2
4kT
þ exp
þ exp
þ exp
4kT
4kT
ð4Þ
The fittings were carried out from 10 to 300 K for 1 and 30 to 300 K for 2 due to the
limit of the present model and complicated magnetic pathways. The parameters
obtained in fitting are: g1 ¼ 1.56, D1 ¼ 0.32 cmꢂ1, zJ10 ¼ 0.15 cmꢂ1 (for 1); g2 ¼ 1.38,
D2 ¼ ꢂ0.052 cmꢂ1, zJ20 ¼ 0.091 cmꢂ1 (for 2). The positive zJ0 values in these two
complexes suggest ferromagnetic coupling between Ln (Tb (1) or Dy(2)) ions and

Lanthanide–radical complexes
2837
2.0
1.5
1.0
0.5
0.0
1.0
8
6
5
4
3
2
1
0
0.8
0.6
0.4
0.2
0.0
7
6
5
4
3
2
1
0
2
4
6
8
10 12 14 16 18 20 22
0
2
4
6
8
10 12 14 16 18 20 22
Temperature (K)
Temperature (K)
Figure 4. Temperature dependence of the in-phase (ꢄ0 round points) and out-of-phase (ꢄ00 square points)
components of the alternating-current susceptibility for 1 under zero dc field at 1250 Hz (left) and for 2 under
1000 Oe dc field at 1400 Hz (right).
nitronyl nitroxide radicals. The parameters of 1 are similar to a four-spin Tb-based
lanthanide–radical complex [12], whose magnetic susceptibility was treated using the
same simplified model. These two complexes, whose structures are very similar to
reported SMMs [9, 22], were expected to be new SMMs. Therefore, alternating-current
susceptibilities for these two complexes were carried out (as shown in figure 4), but
unfortunately, we did not observe the signal of imaginary components (ꢄ00M) of these
two complexes even at 2.0 K. Thus, we do not think 1 and 2 express magnetic ordering
above 2.0 K.
In these reported radical–metal complexes, compared to transition metal ions
[23, 24], lanthanide ions are usually employed to construct SMM due to their large
unquenched angular momentum, but in this article, 1 does not express SMM behavior
mainly due to the following reasons: first, the symmetry around lanthanide is D2d, while
the symmetry around lanthanide in [Tb(hfac)3(NITPhOEt)2] [9] and
[Tb(hfac)3(NITPhSMe)2] [22] is D4d, which could be the main factor to form SMM.
Moreover, as mentioned above, in 1, the shortest distance between the uncoordinated
˚
N–O moieties is 4.042 A, which is shorter than that in [Tb(hfac)3(NITPhOEt)2] [9]. This
shorter distance causes more significant intermolecular interactions, which might
exclude the possibility of SMM. Compared to a reported complex [25], 2 is very similar
to a tri-spin complex in bond lengths and bond angles, but ꢄMT versus T curves express
different tendencies. These behaviors might be caused by electron effects of sulfurs in
[Dy(hfac)3(NITPhSMe)2] [25].
4. Conclusion
Two lanthanide–radical complexes with 2-(40-ethoxy-30-methoxyphenyl)-4,4,5,5-tetra-
methylimidazoline-1-oxyl-3-oxide as radical ligand were synthesized and characterized
structurally and magnetically. Both complexes display radical–Ln(III)–radical tri-spin
structures. Magnetic measurements reveal that the coupling between the central ion and
the organic radicals are ferromagnetic.

2838
C. Wang et al.
Supplementary material
CCDC 848260 (1) and 848263 (2) contain the supplementary crystallographic data for
this article. These data can be obtained free of charge from The Cambridge
Crystallographic Data Centre via www.ccdc.cam.ac.uk/data_request/cif
Acknowledgments
This work was supported by the National Natural Science Foundation of China
21101096, 90922032, 21071085, 20971072, NSF of Tianjin 09JCYBJC05500, Research
Fund for the Doctoral Program of Higher Education 20100031120013, and
Fundamental Research Funds for the Central Universities.
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