The ability of a silyl group to stabilize a carbocation P to silicon, the P-effect, is directly related to the electron-withdrawing ability of the groups on silicon. This was shown by using the degree of syn addition of bromine to (E)-P-silylstyrenes as a measure of the stabilizing ability. With the exception of alkoxysilanes and phenoxysilanes, a good correlation between the degree of the P-effect and the group electronegativity of the silyl group is observed. ...
[Hojo, Makoto; Murakami, Chikara; Aihara, Hidenori; Komori, Ei-ichi; Kohra, Shinya; et al. Bulletin de la Societe Chimique de France, 1995 , vol. 132, p. 499 - 508]
