Stable Silaimines with Three- and Four-Coordinate Silicon Atoms

The reactions of silylenes with organic azides are quite diverse, depending on the substituents of the silylene center and on the nature of the azide employed. Elusive silaimine with three-coordinate silicon atom L1SiN­(2,6-Triip2-C6H3) (5) {L1 = CH­[(CCH2)­(CMe)­(2,6-iPr2C6H3N)2] and Triip = 2,4,6-triisopropylphenyl} was synthesized by treatment of the silylene L1Si (1) with a sterically demanding 2,6-bis­(2,4,6-triisopropylphenyl)­phenyl azide (2,6-Triip2C6H3N3). The reaction of Lewis base-stabilized dichlorosilylene L2SiCl2 (2) {L2 = 1,3-bis­(2,6-iPr2C6H3)­imidazol-2-ylidene} with Ph3SiN3 afforded four-coordinate silaimine L2(Cl2)­SiNSiPh3 (6). Treatment of 2,6-Triip2C6H3N3 with L3SiCl (3) (L3 = PhC­(NtBu)2) yielded silaimine L3(Cl)­SiN­(2,6-Triip2-C6H3) (7) possessing a four-coordinate silicon atom. The reactions of L3SiN­(SiMe3)2 (4) with adamantyl and trimethylsilyl azide furnished silaimine compounds with a four-coordinate silicon atom L3(N­(Ad)­SiMe3)­SiN­(SiMe3) (8) (Ad = adamantyl) and L3(N­(SiMe3)2)­SiN­(SiMe3) (9). Compound 8 was formed by migration of one of the SiMe3 groups. Compounds 5–9 are stable under inert atmosphere and were characterized by elemental analysis, NMR spectroscopy, and single-crystal X-ray studies.