Synthesis, characterization, and computational studies of 6-(RR′N)-nido-5,7-C2B8H11:: A polyborane cluster with a cage-boron having an exopolyhedral dative boron-nitrogen double bond

The reactions of the arachno-4,6-C(2)B(7)H(13) carborane with the secondary and primary amines, Me(2)NHBH(3) and (t)BuNH(2)BH(3), in ionic liquid media result in both boron-insertion into the cage at a position across the two cage-carbons and additional hydrogen-elimination via the reaction of a hydridic B-H with a protonic amine N-H hydrogen to produce the 6-(RR'N)-nido-5,7-C(2)B(8)H(11) carboranes. Computational characterizations of these compounds and the previously reported 6-ClC(6)H(4)-9-(RR'N)-nido-6-NB(9)H(10) azaboranes indicate that the amine-nitrogens form unique exopolyhedral dative B=N double bonds with a cage-boron.