2
984
J.-C. Chang et al. / Polyhedron 29 (2010) 2976–2984
J, p and h. The values for the magnetic coupling constant, J, obtained
from the fitting for diiron(III) in each of these compounds are col-
lected in Table 5. Several interesting facts are revealed from this ta-
ble. Firstly, the triphenylphosphine compound 3g has the lowest J
value among these dicationic diferrate salts. Secondly, the unsym-
metrical dicationic diferrate salts have lower J values than geminal
diferrate ILs (3a < 3c < 3d; 3b ꢂ 3e < 3f). Thirdly, the J values of the
dicationic diferrate salts synthesized in this work are apparently
lower than those of monocation diferrate salts reported previously.
Last and most striking fact is that the J values of compounds con-
higher than that of monocationic salts whereas the magnetic cou-
pling constant in dication is lower than that of monocationic ones.
Acknowledgments
The financial support from the National Science Council of the
Republic of China is gratefully acknowledged (NSC-96-2113-M-
006-014-MY3). We would like to thank the instrument centers of
National Taiwan University (Mr. Un-Cheong Sou for the magnetic
susceptibility data), National Tsing Hua University (Mrs. Pei-Lin
Chen for the X-ray single crystal data), and National Cheng Kung
University (Mr. Shr-Tza Lin for the magnetic susceptibility data,
Mrs. Chia-Chen Tsai for the element analysis data, and Mrs. Ru-
Rong Wu for NMR measurements). We would also like to thank
professor Hua-Fen Hsu, Dr. Chen-I Yang, and Yi-Fang Tsai for mag-
netic discussions.
2ꢀ
taining bent [Cl
3
Fe–O–FeCl
3
]
(in which the dication contains pro-
pyl linkage) are either close or higher than those of the
2ꢀ
corresponding compounds containing linear [Cl
3
Fe–O–FeCl
3
]
(in
which the dication contains butyl linkage), that is, 3a ꢂ 3b;
3
c > 3e; 3d > 3f. This trend is reverse to what were reported in pre-
2
ꢀ
vious studies which indicated that the linear [Cl
3
Fe–O–FeCl
3
]
has
larger antiferromagnetic interaction (lower S and
v
M
T values but
2
ꢀ
higher J value) than that of the bent [Cl Fe–O–FeCl
3
3
]
[16,17].
Appendix A. Supplementary data
These facts indicate that the J value is not solely determined by
the Fe–O–Fe bond angle. It is the result of combined effects of sev-
eral factors such as conformational arrangement in space (or called
steric effect), and weak hydrogen bonding between the bridged
The packing structure of dicationic diferrate ionic liquids in the
unit cell, crystallographic system, and space group, and the ele-
ment analysis data of these ionic liquids are shown in Fig. S1.
The crystallographic data in CIF and Word format are shown in Ta-
bles S1–S42.
2
ꢀ
2 6
oxygen atom of the [Fe Cl O] anion and the dicationic moiety.
It is worth mention that in the monocationic diferrate compound,
it is possible for the two separate monocations to locate and refine
their positions compared to the dications in the dicationic diferrate
compounds. The accurate resolve the weights of each factor appar-
ently require further more careful and thorough study.
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.5. Solubility description
[
[
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[
[
2 3
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[
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4
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2 6
A new type of dicationic salts, which contain [Fe Cl
O]2 anions,
ꢀ
was synthesized. These diferrate salts have good thermal stability
and are soluble in polar solvent. The dicationic structure affects
their magnetic susceptibility and magnetic coupling constant.
The magnetic diferrate dicationic salts which use the triphenyl-
phosphine group had the highest magnetic susceptibility. It was
found that the magnetic susceptibility in a dicationic system is
[
[
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