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

Hadi Dolati; Lars Denker; Juan Pablo Martínez; Bartosz Trzaskowski; René Frank

doi:10.1002/chem.202302494

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

Chemistry. 2023 Nov 8;29(62):e202302494. doi: 10.1002/chem.202302494. Epub 2023 Sep 27.

Authors

Hadi Dolati¹, Lars Denker¹, Juan Pablo Martínez², Bartosz Trzaskowski², René Frank¹

Affiliations

¹ Institute of Inorganic and Analytical Chemistry, Technische Universität Braunschweig, Hagenring 30, 38106, Braunschweig, Germany.
² Centre of New Technologies, University of Warsaw, Banacha 2 C, 02-097, Warszawa, Poland.

PMID: 37584302
DOI: 10.1002/chem.202302494

Abstract

While R₂ C=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.

Keywords: B=NH motif; bond metathesis; boryl carbamoyl complex; diboryl hydrazine; parent iminoborane.