SILICON-COMPOUNDS WITH STRONG INTRAMOLECU LAR STERIC INTERACTIONS .54. ATTEMPTED GENERATION OF A DIAMINOSILYLENE - FORMATION OF SPIROSILANES AND OF RELATED-COMPOUNDS

Treatment of the bulky substituted N,N'-bis(2,6-dimethylphenyl)ethylen ediamine with n-butyllithium and subsequent cyclization with trichloro silane or silicon tetrachloride gives the 2-chloro- and 2,2-dichloro-1 ,3-diaza-2-silacyclopentanes 3 and 4, respectively. Both compounds can easily be converted into the azido- (5) and diazidosilanes (6) and in to the trisilane 7. Chlorine elimination from 4 in the presence of 2,3 -dimethylbutadiene leads to the spirosilane 9 containing a nine-member ed ring, whose structure was confirmed by X-ray crystallography. React ion of 4 with lithium, followed by treatment with isopropanol gives be side other products the compound 10 consisting of two diazasilacyclopc ntane rings linked by a bridging ethylenediamino group. The X-ray stru cture determination of 10 shows that all six nitrogen atoms have a nea rly planar environment. Upon photolysis, the azidosilane 5 provides th e disiladispiro compound 12, presumably via a silanimine intermediate.