Cationic ring‐opening oligomerization of hexamethylcyclotrisilazane and octamethylcyclotetrasilazane

The study of the ring‐opening oligomerization of hexamethylcyclotrisilazane (D 3NH ) and octamethylcyclotetrasilazane (D 4NH ), initiated by methyl triflate in 1,2‐dichloroethane, was carried out. Size‐exclusion chromatography (SEC) analysis indicated the occurrence of an equilibrated reaction between macrocycles such as (SiMe 2 NH) n (with 3 ≤ n ≤ 13) (Me:CH 3 ). Kinetic measurements showed that these oligomerizations are first order relative to both monomer and active center concentrations at the beginning of the reaction. The initial rate constants of propagation ( k p x ) 0 and the ratios of propagation and back‐biting ones ( k p x / k x ) were estimated. Complementary experiments allowed us to propose a mechanism of the oligomerization.