1,3,5-Tri-tert-butyl-2,4,6-triisopropyl-3,5-diaza-1-azonia-2,6-dibora- 4-borata[2.2.0]bicyclohexan, der erste Vertreter der Dewarborazine/ 1,3,5-Tri-tert-butyl-2,4,6-triisopropyl-3,5-diaza-1-azonia-2,6-dibora- 4-borata[2.2.0]bicyclohexane, the First Dewar Borazine

Abstract

The iminoborane iPr-B ≡ N -tBu (1a), metastable at -78 °C, trimerizes to form (iPrBNtBu)₃ (4a) at elevated temperatures. The determination of the molecular and crystal structure reveals 4a to be a Dewar-borazine-type molecule with two short peripheral BN-double-bonds (136 and 138 pm) and an extra-long bridge BN-single-bond (175 pm). The same trimer 4a is formed by addition of la to the diazadiboretidine-type dimer (iPrBNtBu)₂, prepared independently. The ethyloboration and the azidoboration of la with BEt₃ and Me₃SiN₃, respectively, and the cycloaddition of PhN₃ to 1a follow expected patterns.