Trapping of a Transient Base‐Stabilised Alumylene and Alumylene‐Type Reactivity of a Self‐Stabilising Dialumene towards Organic Azides

Abstract

The reduction of a carbene‐coordinated, sterically encumbered terphenyl‐substituted aluminium diiodide, (LRAlI2), yielded a “masked” dialumene (LRAl=AlRL), self‐stabilised through [2+2] cycloaddition with a peripheral aromatic group. During the course of the reaction, a carbene‐stabilised arylalumylene (LRAl:) was generated in situ, which was trapped using an alkyne, generating an aluminacyclopropene or a C−H activated product thereof, depending on the steric bulk of the alkyne. The masked dialumene also underwent intramolecular cycloreversion and dissociation into alumylene fragments, which reacted with various organic azides to yield monomeric or dimeric iminoalanes depending on the sterics of the azide substituent. The thermodynamics of monomeric and dimeric iminoalane formation were probed by theoretical calculations.

Reactions of main group compounds with azides forming organic nitrogen-containing species

“…In 2023, the Braunschweig group reported the intramolecular [2+2] cycloaddition of transient dialumene with a peripheral aromatic group gave a “masked” dialumene Al11 . 90 The reaction of Al11 with p -TolN 3 at 60 °C for 12 h afforded the dimeric iminoalane Al11-P1 in 90% yield with the release of dinitrogen (Scheme 47b). Al11-P1 bears a planar Al 2 N 2 four-membered ring with four Al–N single bonds (1.8564(11) Å and 1.8590(11) Å).…”

Synthesis and Reactivity of a Dialane‐Bridged Diradical

“…A wide range of low-valent aluminum and boron compounds have been shown to react with organic azides, yielding iminoalane and iminoborane products, respectively, often depending upon the steric profiles of the reactants. [72][73][74][75][76][77] The reaction of two equivalents of Mes TerN 3 ( Mes Ter = 2,6-Mes 2 C 6 H 3 , Mes = 2,4,6-Me 3 C 6 H 2 ) with 2 a/b yielded the aluminum imide 4 (Scheme 3). The solid-state structure of 4 (Figure 4) showed an AlÀ N bond length of 1.668(3) Å, which is intermediate between the reported AlÀ N triple bond (1.625(4)Å) [76] and double bond (1.705-(2)Å).…”

Synthese und Reaktivität eines Dialanverbrückten Diradikals

“…Es hat sich gezeigt, dass eine Vielzahl von niedervalenten Aluminium‐ und Borverbindungen mit organischen Aziden reagieren und Iminoalan‐ bzw. Iminoboranprodukte ergeben, die häufig von den sterischen Profilen der Reaktanten abhängen [72–77] . Die Reaktion von zwei Äquivalenten Mes TerN 3 ( Mes Ter=2,6‐Mes 2 C 6 H 3 , Mes=2,4,6‐Me 3 C 6 H 2 ) mit 2 a/b ergab das Aluminiumimid 4 (Schema 3).…”