Aminosilanolates as precursors of four- and eight-membered (SiNSiO)-rings

The amino-di-tert-butyl-silanol (1) crystallizes as a dimer. It forms sodium- and potassium aminosilanolates (2, 3) in the solid state, which crystallize as hexagonal prisms. In the reaction of the alkali-aminosilanolates with halosilanes, 1-amino-1,3-disiloxanes (Me3C)2Si(NH2)OSiRR′R″ are obtained; (4: R=R′=CMe3, R″=H; 5: R″=Cl; 6: R=Me, R′=CMe3, R″=F; 7: R=R′=NMeSiMe3, R″=F; 8: R=R′=NCHMe2SiMe3, R″=F; 9: R=R′=N(CHMe2)2, R″=F). The formation of 5 is accompanied by two by-products, a six-membered Si(SiO)2NH-ring (10) and a 1,3-diamino-1,3-disiloxane (11). The treatment of 6 with n-C4H9Li followed by LiF-elimination results in an eight-membered (SiOSiN)2-ring (13), the analogous reaction of 7 and 8 leads to the formation of four-membered (SiOSiN)-rings (14, 15). The results of the crystal structure determinations of 2, 3, 9 the lithium salt of 8 (12) and quantum chemical calculations for four-membered R2SiOSiNR′-rings (R, R′=H; R, R′=Me; R, R′=CMe3) are reported.