SILICON-COMPOUNDS WITH STRONG INTRAMOLECULAR STERIC INTERACTIONS .47. TRISILACYCLOBUTANIMINES

Treatment of hexa-tert-butylcyclotrisilane (4) with aryl isocyanides leads to the trisilacyclobutanimines 5-8. Reaction of the 1,4-diisocyanobenzene derivative 7 with two molecules of 4 leads to the double insertion product 9, the X-ray structure analysis of which shows the Si3CN framework atoms to be almost exactly coplanar. The planes of the two four-membered rings are strictly parallel whereas the linking phenylene group forms a 71.6-degrees angle with these planes. The most striking features of these and of related compounds are their dark colours with longest wavelength absorptions between 500 and 540 nm.