PREPARATION AND REACTIONS OF TRIS(TRIMETHYLSILYL)SILYL SILICON DERIVATIVES AND RELATED TETRASILYLSILANES

Treatment of (Me3Si)3SiLi with various silicon halides has given a range of compounds of the type (Me3Si)3SiSiR2X (R = Me, X = H; R = Ph, X = Cl etc.). These compounds can be converted into other derivatives by simple substitution reactions at the Si-X centre. Symmetrical pentasilanes (XMe2Si)4Si (X = Cl, F, and OAc) have been prepared from (Me3Si)4Si. The reactivities of these species have been compared with those of analogous carbon-centred compounds eg. (Me3Si)3CSiR2X. Substitution reactions in the silicon-centred compounds are much more rapid than those in the carbon analogues, presumably reflecting the increase in bond lengths around the central atom which makes the functionalized silicon centre less sterically hindered and more susceptible to attack.