X-ray analysis of 1,3-dioxa-6-aza-2-silacyclooctane derivatives

Abstract X-ray analysis has been conducted on four dioxaazasilacyclooctanes R 2 Si(OCH 2 CH 2 ) 2 NR′ with R = C 6 H 5 , R′ = CH 3 (IV); R = C 6 H 5 , R′ = (CH 3 ) 3 C (V); R = CH 3 , R′ = C 6 H 5 (VI) and R = R′ = C 6 H 5 (VII). The interatomic distances SiN measured for these compounds had the values: 2.68 (IV), 3.16 (V), 3.19 (VI) and 3.08 A (VII), indicating weak nitrogen—silicon interaction and a virtual lack of coordinate Si ← N bonding. The data of other authors and our own evidence suggest that the Si ← N interaction in these compounds is strongly influenced by the electronic effects of Si- and N-substituents and, in particular, by the steric effects of the latter.