Ambient Temperature Isolation of a Monatomic Boron(0) Complex.

The first bottleable example of a neutral Group 13 atom bound only by neutral donor ligands (L) has been fully characterized by spectroscopic methods and its structure determined by a single-crystal X-ray diffraction study. A two-coordinate paramagnetic LB complex can readily be accessed through a facile reduction reaction and is stabilized by π-accepting cyclic (alkyl)(amino)carbene (CAAC) ligands. Further reduction of (CAAC)B leads to the isolation of a stable diamagnetic boride anion.

Aromaticity transfer in an annulated 1,4,2-diazaborole: facile access to symmetric 1,4,2,5-diazadiborinines.

A tricyclic annulated 1,4,2-diazaborole is readily accessed reaction of a bidentate pyridyl-carbene ligand with MesBBr followed by reduction. Dearomatization of the flanking rings is shown to increase reactivity of this heterocycle in the form of a B-centred alkylation with MeI. Its reaction with hydrido-, fluoro-, and chloro-boranes reveal an unprecedented ring expansion reaction to form a diverse family of BCN heterocycles, reduction of which allows facile access to the first examples of symmetric 1,4,2,5-diazadiborinines.