Iminoboranes With Parent B=NH Entity: Imino Group Metathesis, Nucleophilic Reactivity and N−N Coupling

Abstract

While R2C=N−R double bonds in organic imines are well established, the related iminoboranes R−B=N−R are either prone to oligomerization or can only be stabilized at sufficient steric congestion. In particular, the examples of unsubstituted parent B=N−H entity are rare. We demonstrate that the amino imidazoline‐2‐imine ligand system (HAmIm) not only gives rise to the isolation of a parent (AmIm)B=N−H iminoborane, but also to species of type (AmIm)B=N−SiMe3 with concomitant stabilization by lithium bromide. The double bond character in these systems is unambiguously corroborated by DFT calculations. The steric accessibility of the (AmIm)B=NH unit allows facile reactivity including metathesis reactions with C=O and C=S bonds, nucleophilic addition toward organic and organometallic carbonyl compounds, but also oxidative N−N coupling within a dimeric unit. Thus, the chemical behavior of the (AmIm)B=N−H and (AmIm)B=N−SiMe3 is distinctly different from that of organic imines.