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

200 Silyl Radicals in Polymers and Materials
Interestingly, 1,2-adducts 33, 34 and 35 have also been obtained in a 69 %
yield and a ratio of 1:10:9, when PhSi(SiMe3) 3 is photolysed in the presence of
C60, which clearly indicates the intermediacy of silyl-adduct radical 31 followed
by an intramolecular addition to the phenyl ring (32) prior to combining with
Me3Si: radicals to provide these unusual adducts (Scheme 8.7) [30,31].
Me 3Si
Me 3Si
Si
Me3Si Si
Me3Si H
31 32
Me
H
3Si
Si
Me3Si H SiMe3 33
Me 3 Si
H
Me3Si Si
Me3Si H
SiMe 3
Me 3Si
H
Me3Si Si
Me3Si H
34 35
Scheme 8.7 Reaction paths for the formation of 1,2-adducts 33, 34 and 35 obtained from the
photolysis of PhSi(SiMe3) 3 in the presence of C60
The photoreaction of polysilanes with C60 has also been investigated [35].
Reaction (8.16) shows an example in which the irradiation in benzene with a
low-pressure mercury-arc lamp afforded a product that contains 14 wt% of C60
into the polysilane chain. The incorporation of C60 into the polysilane backbone
has not been observed upon irradiation with l > 300 nm, when the
cleavage of Si w Si bond does not take place. The adduct obtained from Reaction
(8.16) has a lower oxidation potential than C60( þ 0:77 vs þ 1:21 V) and a
lower reduction potential than polysilane ( 1:24 vs 2 V).
Ph
Si
Me n
+
C 60
hν (254 nm)
C 60 —polysilane
(8.16)
Laser flash photolysis experiments showed that the C60 triplet state ( 3 C 60 ),
obtained by 532 nm excitation, reacts with poly(methylphenylsilane) by an