Chemistry Reference
In-Depth Information
Fig. 9.30 Temperature
dependence of the magnetic
susceptibility
w
M
of [Pt
2
(
n
-
PenCS
2
)
4
I]
1
(5)[
35
]. The
solid line
represents the fitting
to estimate the impurity spin
concentration. The estimated
Curie spin concentration is
only 0.11 %
iodine in an appropriate solvent [
37
,
38
]. The reported synthetic conditions are listed in
Table
9.4
. With elongation of the ligand's alkyl chain, the isolation of target compound
becomes difficult due to its high solubility. The Ni MMX-chain compounds can be
stored without decomposition for several months under an inert atmosphere in a
refrigerator but gradually decomposes upon exposure to air at room temperature.
9.3.2 Crystal Structures
9.3.2.1
[Ni
2
(RCS
2
)
4
I]
1
(R
¼
Me (7), Et (8))
Me (7), Et (8)) crystallize in the monoclinic
P
2/
n
and
C
2/
c
space groups, respectively, and have analogous structures with the corresponding
diplatinum compounds, [Pt
2
(RCS
2
)
4
I]
1
(R
¼
Me (1), Et (2)) [
37
,
38
]. Each nickel
compound is isostructural but not isomorphous with the corresponding platinum
complex. The crystal structure is exemplified with that of the compound 8 [
38
]. The
crystal structure of 8 is shown in Fig.
9.31
.
The crystal of compound 8 consists of neutral 1D chains with a repeating
-Ni-Ni-I- unit lying on the crystallographic twofold axis parallel to the
b
axis.
Two nickel atoms are bridged by four dithiopropanato ligands and the Ni-Ni
distance is 2.5479(7)
˚
, which is 0.22
˚
shorter than the distance between the
mean planes defined by the four sulfur atoms (2.77(3)
˚
). This Ni-Ni distance is
marginally shorter than that of the dinuclear Ni
2+
-Ni
2+
complex, [Ni
2
(MeCS
2
)
4
]
(2.564(1)
˚
), but longer than [Ni
2
(EtCS
2
)
4
] (2.5267(10)
˚
)[
79
]. The two NiS
4
square planes are twisted by 28.2(9)
from the eclipsed structure. In the case of
diplatinum complexes, it is known that the Pt-Pt distance tends to shorten with
increasing the formal oxidation number of the platinum atoms due to the Pt-Pt bond
¼
[Ni
2
(RCS
2
)
4
I]
1
(R
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