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Mn
II
Mn
II
O
Mn
III
Mn
III
O
Mn
II
Mn
II
[Mn
6
(O)
2
Piv
10
]
(a)
O
N
[Mn
6
(O)
2
Piv
10
]
+
N
O
L
20
(b)
Figure13.4
Antiferromagneticinteractionbetweenthemagneticmomentsofadjacentclusters(a).Theformation
ofadifferencemagneticmoment inanonhomogeneousantiferromagneticchainwithanitroxidebridge(b).
(L
7
, makes the bridging coordination mode of the O
•
-N-C
=
N
O fragment impossible because of the
steric requirements of the
tert
-butyl pivalate groups with the atoms of the R group.
192
The replacement of the coordinated acetonitrile molecules by nitroxide is an effective method for the
synthesis of complex multispin systems. This procedure for the synthesis of mixed metal heterospin
compounds with direct coordination of the nitroxyl fragment was demonstrated for the reaction of the
trinuclear [Co
2
Gd(NO
3
)
)
→
Piv
6
(CH
3
CN)
2
] with L
20
Piv
6
(L
20
)
2
]
p
,
d
,
f
- heterospin complex. Each molecule of this complex contains a specific exchange cluster, which
is a “chain” of five paramagnetic centers separated by a system of chemical bonds (Scheme 13.19). The
as an example, which gave the [Co
2
Gd(NO
3
)
O
N
O
O
O
O
O
O
O
O
O
O
Gd
O
N
Co
N
O
Co
N
N
O
O
O
O
O
O
[Co
2
Gd(NO
3
)Piv
6
(L
20
)
2
]
Scheme 13.19
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