Silyl Substituted Silicon Hydrides

Reduction of a variety of organic derivatives was carried out by using (Me3Si)2Si(H)Me under normal conditions, i.e., AIBN at 80 °C [108]. The mono-reduction of a gew-dichloride is shown as an example in Reaction (4.67). With two silyl substituents, (Mc3 Si)2Si(H)Me is an effective reducing agent which allows the formation of the desired product to be favoured due to a slower hydrogen transfer. 

---

Scheme 6.20 Reaction intermediates involved in the autoxidation of silyl substituted silicon hydrides (R = Me or MesSi)...

Oxidation Studies on Silyl-Substituted Silicon Hydrides... 

OXIDATION STUDIES ON SILYL-SUBSTITUTED SILICON HYDRIDES... 

The reaction of metal carbonyl dimers with silicon hydrides also probably involves an initial oxidative addition step. Chiral silyl-cobalt and silyl-manganese carbonyl complexes have been obtained through the reaction of optically active organosilicon hydrides with metal carbonyls65 68 (equation 15 and 16). Phosphine-substituted cobalt complexes were similarly obtained by reaction of a chiral hydrosilane with Co2(CO)6L2 [L = PPh3, P(OPh)3, P(c-C6Hn)3]69. 

Results that suggest that the silicon analogue of the t-butyl ion, Me3Si +, can be produced as the perchlorate have been reported27. Finally, the iron-substituted material Cp(R3P)2Fe-SiR2 also has been reported as a possible product, obtained as usual by hydride abstraction from the analogous silyl hydride33. 

The results presented in the previous paragraphs demonstrate that the extreme reactivity of three-coordinate silyl cations is significantly reduced in arene solvents by intermolecular polar-ir (p-it) interaction between the cation and the tr-system of the arene. Two model systems have been suggested and have been experimentally verified in which this p-n interaction is employed to modulate the cation character of the silicon atom intramolecularly and to control the reactivity of the silicon cation [34, 35]. Both classes of silyl cations, the cyclic disilyl-substituted arenium ions 71, 72 synthesized in our group [33,49,73] and the weta-terphenyl-substituted silyl cations 73 from the Siegel group [34, 74, 75], will be discussed here as examples for intramolecular stabilized silylated arenium ions. Both classes of silyl cations were synthesized by the standard BCS hydride-transfer reaction... 

---