"Front Matter". In: Organosilanes in Radical Chemistry - Index of

188 Silyl Radicals in Polymers and Materials
Si
Si
Si
x
Si
Si
3
Si
Si
Si Si
Si Si
S H i
Si
Si
where x = 1, 2 or 3
Scheme 8.1 Radical-based degradation of polysilanes
Si
x
Si
Si
Si
Si
Si Si
Si Si
Direct evidence that a hydrogen abstraction from poly(hydrosilane)s affords
the corresponding silyl radical was obtained by EPR spectroscopy [13]. The
photochemical behaviour of poly(n-hexylhydrosilane) (4) in the presence and
absence of t-BuOOBu-t is shown in Figures 8.2a and 8.2b, respectively. When
irradiation was cut off in the experiment with peroxide, the remaining signal is
that of Figure 8.2b, which persisted for several hours. The spectrum in Figure
8.2c, obtained by subtracting spectrum b from spectrum a, is characterized
by the coupling of the unpaired electron with two hydrogens (7.10 G) and
a
b
c
15 Gauss
Figure 8.2 (a) EPR spectrum obtained by photolyzing a solution of poly(n-hexylhydrosilane)
and t-BuOOBu-t in cyclohexane; (b) Spectrum (g ¼ 2:0057) observed when irradiation was
discontinued; (c) Spectrum (g ¼ 2:0047) obtained by subtracting spectrum b from spectrum a.
Reprinted with permission from Reference [13]. Copyright 1997 Elsevier.