Chemistry Reference
In-Depth Information
-
Fig. 9
I
···
Iinteractionsin(EDT-TTF-I
2
)
2
(PbI
3
) with the polymeric (PbI
3
)
∞
anionic
chains
with a charge per iodine atom of - 0.33 [68], when compared with the two-
dimensional (Pb
5
/
6
6
I
2
)
3
layers [69] where the charge per iodine atom
amounts to - 0.17 for the same oxidation state of EDT-TTF-I
2
(
/
1
=0.5). In
the latter, the inorganic layers exhibit the CdI
2
structuretypewhiletheexact
negative charge of the layer is governed by the presence of a specific number
of lead vacancies. The shortest I
donor
···
ρ
I
anion
distances (3.81, 4.09
A
), albeit
longer than in the other salts described above, are still much shorter than the
I
I separation across the van der Waals gap in 2H-PbI
2
(4.95A).
Polyhalometallates are also particularly interesting since they often exist in
a paramagnetic state, allowing for investigation of possible
···
-d interaction in
these salts between the conducting, delocalized electrons of the organic slabs
(the
π
electrons) and the localized spins of the counter ions, for example,
the
S
=5
π
2FeCl
4
-
ions [71-73]. Enoki et al. have reported the very first ap-
proach aimed at associating halogen bonding to the
/
-d interaction, first
in the (EDO-TTF-Br
2
)
2
(FeBr
4
) salt [74], then in two salts of EDT-TTF-Br
2
with paramagnetic FeBr
4
-
π
and diamagnetic GaBr
4
-
[75]. These three sys-
tems are isostructural and exhibit Br
donor
···
Br
anion
interactions at distances
(3.65-3.68A) associated with a weaker, type I halogen interaction. Neverthe-
less, the antiferromagnetic ordering of the FeBr
4
-
anion lattice was shown to
affect the transport properties of the conducting
π
electrons, demonstrating
Search WWH ::
Custom Search