STEREOCHEMISTRY OF HYDRIDE ION DISPLACEMENT FROM SILICON. ENHANCED RATES AT BRIDGEHEAD AND 4-RING SILICON ATOMS¹

Molecular Variations Based on Isosteric Replacements

“…Thus, 1-chloro-1-sila-bicyclo-(2,2,1)-heptane can still be hydrolyzed by an attack on the vacant d orbital [236]. Even when located in the center of a quaternary structure, the risk exists that the silicon atom will be attacked.…”

Strained cyclic organosilicon compounds

“…In view of the apparent distortion of bond angles resulting in the formation of a considerably strained ring system (8), /LlllJ should possess a more energetic ground state than its ring homolog. This would favor ring opening of the former in preference to the latter, A theoretical consideration of the transition state of a silacyclobutane derivative in a nucleophilic displacement reaction has been previously reported by Sommer (11). He has explained the hi^ reactivity of l-methyl-l-silacyclobutane flXj in hydrolysis reactions by a consider ation of the structure-reactivity relations resulting from steric factors.…”

Strained cyclic organosilicon compounds

“…In 1957f Sommer and co-workers (11) Thus, the displacement of hydride ion by hydroxide ion was found to proceed much more readily at four-membered ring silicon atoms than at silicon in other five-and six-membered ring silicon hydrides (l4). In this respect, cyclic silicon hydrides exhibit a complete reversal of the structure-reactivity relationships observed for displacements at carbon (15)• To explain the enhanced reactivity of the four-membered ring silicon hydrides.…”