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

Carbon-Centred Radicals 33
k r
U• R
R 3 SiH R 3SiH
k H
Scheme 3.1 Free-radical clock methodology
UH RH
In Table 3.1 are collected the rate constants with various silanes and silanthrane
derivatives 4–7 and the available Arrhenius parameters for some of
them.
H H
Si
Si
H H
4
H
X
Si
Me
5 X = O
6 X = SiMe 2
7 X = S
Table 3.1 Rate constants (at 80 8C) a and Arrhenius parameters for the reactions of
primary alkyl radicals with silicon hydrides b
Silane Radical k=M 1 s 1 log A=M 1 s 1 Ea=kJ mol 1 Reference
Et3SiH 1 5:2 103 8.7 33.5 [5]
PhSiH3 1 2:9 104c [6]
Ph2SiH2 1 5:6 104c [6]
Ph3SiH 1 4:6 10 4c
5 1 2:2 104 [7]
6 1 4:5 104 [7]
7 1 8:7 104 [7]
4 2 2:1 106 [8]
(Me3Si)Me2SiH 1 2:5 104 9.0 31.4 [6]
RMe2SiH d
1 3:6 10 4 9.0 30.1 [6]
(Me3Si) 2MeSiH 1 1:5 10 5 8.9 25.1 [9]
(Me3Si) 3SiH 3 1:2 10 6 8.9 18.8 [10]
(MeS) 3SiH 2 3:9 10 5 [8]
(i-PrS) 3SiH 2 3:7 10 5 [8]
a At 80 8C, if not otherwise mentioned.
b Benzene, tert-butylbenzene or 1,3-di-tert-butylbenzene were used as the solvent; for errors see the original
references.
c At 110 8C.
d R ¼ SiMe2SiMe3
[6]