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 (LSiN)-Si-1(2,6-Triip(2)-C6H3) (5) {L-1 = CH[(C=CH2)(CMe)(2,6-iPr(2)C(6)H(3)N)(2)] and Triip = 2,4,6-triisopropylphenyl) was synthesized by treatment of the silylene (LSi)-Si-1 (1) with a sterically demanding 2,6-bis(2,4,6-triisopropylphenyl)phenyl azide (2,6-Triip(2)C(6)H(3)N(3)). The reaction of Lewis base-stabilized dichlorosilylene (LSiCl2)-Si-2 (2) {L-2 = 1,3-bis(2,6-iPr(2)C(6)H(3))imidazol-2-ylidene} with Ph3SiN3 afforded four-coordinate silaimine L-2(Cl-2)SiNSiPh3 (6). Treatment of 2,6-Triip(2)C(6)H(3)N(3) with (LSiCl)-Si-3 (3) (L-3 = PhC(NtBu)(2)) yielded silaimine L-3(Cl)SiN(2,6-Triip(2)-C6H3) (7) possessing a four-coordinate silicon atom, The reactions of (LSiN)-Si-3(SiMe3)(2) (4) with adamantyl and trimethylsilyl azide furnished silaimine compounds with a four-coordinate silicon atom L-3(N(Ad)SiMe3)SiN(SiMe3) (8) (Ad = adamantyl) and L-3(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.