Chemistry Reference
In-Depth Information
O
R'
R'
R'
H
PhCHO
COCl
2
N
N
N
N
R'NHNH
2
N
N
H
pyridine
Ph
Ph
Ph
15
14
O
O
O
R'
R'
[ox]
R'
R'
RCHO
N
N
N
R'
R'
N
N
NH
N
NH
2
N
N
HN
NH
2
R
R
H
16
7
17
Scheme 7.5
O
O
R'
R'
N
N
N
R'
R'
COCl
2
or
(Cl
3
CO)
2
C=O
N
NH
2
N
NH
2
R'NHNH
2
N
R
2
16
7
Scheme 7.6
S
S
R'
R'
R'
R'
R'
R'
R'
R'
ox
N
N
N
R
aney N
i
N
N
N
N
N
NH
N
N
NH
ox
N
N
HN
HN
R
R
H
R
H
R
8
18
19
6
Scheme 7.7
of weeks. The lone general exception is the family of 6-oxoverdazyls
7
with methyl substituents on
each of the two nitrogen atoms, which disproportionate (Section 7.2.3.3) - although this process can be
sufficiently slow to render some derivatives stable as opposed to long lived/persistent. Verdazyls are air
and water stable and remain monomeric in solution and the solid state; there are no examples of verdazyl
dimerization in solution (the electronic spectrum of verdazyl
27
is concentration dependent, but in this
instance the association-driven spectral changes arise from the amphiphilic nature of the molecule rather
than radical - radical association
53
). The lone solid state example of a verdazyl dimer is the intramolecularly
associated ferrocene-linked diradical
28
.
54
In the solid state the two verdazyl rings are eclipsed and have
3.18 A) which is well within van der Waals separation (and significantly
∼
a centroid-to-centroid distance (
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