Unusual, thermally stable, sublimable aminoboranes B(NHAr)X2(X = Cl, F, or NH2); X-ray crystal structure of bis(amino)(2,4,6-tri-t-butylphenylamino)borane, B(NH2)2(NHAr)

Abstract

The sterically demanding 2,4,6-tri-t-butylamido lignad (HAr) confers unexpected thermal stability on the title boranes B(NHAr)X₂[X = Cl, (2); F,(3); or NH₂, (4)], each of which is sublimable without elimination of HX; the difluoroborane (3) has significant BN double-bond character as is evident from magnetically distinct F^– ligands, only one of which (presumably the trans) is coupled to the NHAr proton; compound (4) has trigonal planar boron with one of the B–NH₂ bonds significantly linger than the other, 1.470(4) and 1.437(4)Å, and each longer than B–NHAr, 1.412(4)Å.