THF.B3H7 reacts with RB.tplbond.NR (1, R = CMe3) to yield the m-aminodiborane I, which crystallizes in the triclinic space group P.hivin.1. The reaction of B3H7 with the azadiboriridine II leads to the known heterobicyclic III and the novel IV (R = CMe3). Product III is considered to represent a diaza-arachno-octaborane deriv. The iminoborane 1 reacts with B5H9 in the presence of lutidine (L) to give the ionic product [LBR:NHR][B9H14] (7); the authors' earlier report on the formation of the aza-arachno-heptaborate [LH][NB6H8R2] has to be revised. The products from the reaction of B5H9 with NB2R3 are III and IV.