Stable Silaimines with Three- and Four-Coordinate Silicon Atoms

Abstract

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 L(1)SiN(2,6-Triip(2)-C(6)H(3)) (5) {L(1) = CH[(C═CH(2))(CMe)(2,6-iPr(2)C(6)H(3)N)(2)] and Triip = 2,4,6-triisopropylphenyl} was synthesized by treatment of the silylene L(1)Si (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 L(2)SiCl(2) (2) {L(2) = 1,3-bis(2,6-iPr(2)C(6)H(3))imidazol-2-ylidene} with Ph(3)SiN(3) afforded four-coordinate silaimine L(2)(Cl(2))SiNSiPh(3) (6). Treatment of 2,6-Triip(2)C(6)H(3)N(3) with L(3)SiCl (3) (L(3) = PhC(NtBu)(2)) yielded silaimine L(3)(Cl)SiN(2,6-Triip(2)-C(6)H(3)) (7) possessing a four-coordinate silicon atom. The reactions of L(3)SiN(SiMe(3))(2) (4) with adamantyl and trimethylsilyl azide furnished silaimine compounds with a four-coordinate silicon atom L(3)(N(Ad)SiMe(3))SiN(SiMe(3)) (8) (Ad = adamantyl) and L(3)(N(SiMe(3))(2))SiN(SiMe(3)) (9). Compound 8 was formed by migration of one of the SiMe(3) groups. Compounds 5-9 are stable under inert atmosphere and were characterized by elemental analysis, NMR spectroscopy, and single-crystal X-ray studies.

Facile Access to an NHC‐Coordinated Silicon Ring Compound with a Si=N Group and a Two‐Coordinate Silicon Atom

“…The Si4=N7 (1.625(2) Å) bond length is at the upper range of those found in silaimines (1.550–1.611 Å) . Silaimines were synthesized by the addition of azides to a silylene,–,, or more recently by the addition of SiCl 4 to an NHC‐coordinated amidochloro‐substituted silylene or SiI 4 to an N(SiMe 3 ) 2 and amidinato‐substituted silylene . In addition, unsaturated compounds such as isonitriles and acetylenes reacted with NHC‐coordinated amidochloro‐substituted silylenes to yield silaimines ,.…”

Efficient Synthesis of a NHC‐Coordinated Trisilacyclopropylidene and Its Coordination Behavior

“…For the silaimine silicon atom of 5 a 29 Si NMR chemical resonance was found at −82.7 ppm. Silaimines were recently synthesized by the addition of azides to silylenes ,–,,. In some of these cases exocyclic Si=N bonds were generated ,,,.…”

Bis(silylene)‐Stabilized Monovalent Nitrogen Complexes

“…According to the results of Density Functional Theory (DFT) calculations (vide infra), the formation of 2 proceeds via the monosilylene‐azide adduct 2′ (see below and Figure S5 in Supporting Information ). The formation of 2 designates a very different reactivity compared to that of other silylenes toward organoazides [34–38] . While most of these reactions yield Staudinger‐reaction‐type and/or further reaction products, compound 2 represents an isolable intermediate of a so‐called “interrupted Staudinger‐type” reaction.…”