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F
3
C
CF
3
F
3
C
F
3
C
CF
3
O
O
O
O
O
CF
3
O
Cu
O
F
3
C
Cu
O
CF
3
O
O
N
N
N
N
O
O
O
N
O
N
Hg
N
O
N
CF
3
O
O
Cu
F
3
C
O
O
O
Cu
O
CF
3
F
3
C
O
O
F
3
C
O
CF
3
CF
3
F
3
C
[Cu(hfac)
2
]
4
{Hg[(L
15
)
−
]
2
}
2
Scheme 13.8
(Continued)
framework polymers; this aspect of molecular magnetism research draws heavily on the concepts and
principles of supramolecular chemistry. The formation of layered or framework structures in solid molecu-
lar ferromagnets is a favorable condition for a magnetic phase transition to the magnetically ordered state.
However, for chemical design of molecular magnets, this is a favorable but not sufficient condition. For
a phase transition, the paramagnetic centers in these polymers should be bound by an effective magnetic
exchange pathway. The higher the efficiency of exchange channels in exchange interactions between the
odd electrons of the paramagnetic centers, the higher the T
c
that can be achieved. Success in this field
can be realized through systematic studies on the effect of molecular design, as well as the conditions
of synthesis and crystallization, on the parameters of the resulting molecular magnet (Curie temperature,
spontaneous magnetization, etc.). The search for materials with desirable magnetic properties can be then
be rationalized in terms of magnetostructural correlations. Put another way, the term “molecular mag-
net,” can be interpreted as follows: the word “magnet” has the conventional meaning, and the attribute
“molecular” reflects the methodology of the approach (the structure of the individual starting molecules
and/or ions should allow the formation of a structure favorable for a magnetic phase transition in the
solid state).
Consideration of polymeric systems is begun firstly by considering selectively synthesized 1-D metal-
nitroxide systems, in which exchange interactions between paramagnetic centers
a priori
should be strong.
The interaction between Mn(hfac)
2
·
2H
2
O and L
n
produced chain polymers Mn(hfac)
2
L
n
, where L
n
are
ethyl (L
7
, phenyl (L
12
, hydrogen (L
15
, methyl (L
20
,
n
-propyl (L
21
=
)
)
)
)
)
nitronyl nitroxides, containing R
,
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