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Fig. 9.27 Temperature
dependence of the magnetic
susceptibility of
[Pt
2
(EtCS
2
)
4
I]
1
(2)[
32
]
The magnetic susceptibility exhibits changes in slope near
T
M-S
and a slight swelling
near 160 K. As described in the X-ray Diffuse Scattering section, lateral correlation
between 1D chains rapidly develops in this temperature region. The swelling
observed in magnetic susceptibility seems to have appeared concerning the rapid
development of the lateral correlation, though a clear explanation is not possible at
this time. The spin degree of freedom survives at low temperature and loss of the spin
degree of freedom accompanied by the transition to the ground state of the ACP state
of -Pt
2+
-Pt
3+
-I
-Pt
3+
-Pt
2+
-I
- has not been observed.
9.2.7.3
[Pt
2
(n-PrCS
2
)
4
I]
1
(3)
The temperature dependence of the magnetic susceptibility,
w
M
, of crystalline
samples of 3 is shown in Fig.
9.28
[
76
]. The
w
M
vs.
T
plot below ca. 300 K can
account for paramagnetic impurities and/or lattice and end-of-chains defects. There-
fore, the compound 3 takes the spin-singlet state below 300 K. This is consistent with
the valence-localized state corresponding to ACP or CDW state observed by the
X-ray diffraction study. Above 300 K, on the other hand, the compound 3 exhibits
thermally activated magnetic susceptibility, in accordance with the valence-
fluctuating state corresponding to a dynamic ACP or CDW state.
9.2.7.4
[Pt
2
(n-BuCS
2
)
4
I]
1
(4)
The temperature dependence of the magnetic susceptibility,
w
M
, of crystalline
samples of 4 is shown in Fig.
9.29
[
33
].
w
M
of 4 in the RT phase is on the order
10
5
emu mol
1
, which is in accordance with the results of EPR
measurements (ca. 2
of 2.9
10
5
emu mol
1
)[
77
]. The tail, observed in the
w
M
vs.
T
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