4-MEMBERED, 5-MEMBERED, AND 6-MEMBERED SILYLHYDRAZINE-RING SYSTEMS

Silylhydrazines (RR'R''SiNHNH2, 1-3) and the six-membered-ring [Me2CH)2SiNHNH]2 (4) are formed in reaction of fluorosilanes with lithiated hydrazine. N,N'-Bis(silyl)hydrazines with different silyl groups are obtained in reactions of lithated 1, [(CMe3)2SiMeNHNH2], with F2Si(CHMe2)2 [(CMe3)2SiMeNHNHSiF(CHMe2)2, 5] and of lithiated 2, [(CMe3)2-SiFNHNH2], with chlorosilanes [(CMe3)2SiFNHNHSiMe3R, R = Me (6) and CMe3 (7)]. [(Me2-HC)2N]2SiFNHNH2 (3) reacts with BuLi to give a five-membered cyclic silylhydrazine, (NHSiR2)2NNH2 (8), and LiF. 8 isomerizes above its melting point, and the six-membered-ring (R2SiNHNH)2, R = N(CHMe2)2 (9), is formed. The reaction of 5-7 with BuLi leads to the formation of six-membered rings, (R2SiNHNHR')2 [R = CHMe2, R' = SiMe(CMe3)2 (10); R = CMe3, R' = SiMe3 (11), R' = SiMe2CMe3 (12)], and LiF. Fluorine-chlorine exchange occurs in the reaction of lithiated 5 with ClSiMe3. FSiMe3 and the four-membered cyclic silylhydrazine [(CMe3)2SiMeNHNSi(CHMe2)2]2 (13) are obtained by thermal LiCl elimination from the resulting salt. The crystal structures of 12 and 13 have been determined and are discussed.