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.