Syntheses, Structures, and Reactivities of N-Heterocyclic Carbene-Coordinated Aminoborane Complexes.

Recent research has attracted considerable attention toward N-heterocyclic carbene-coordinated boranes (NHC-borane) and their B-substituted derivatives because of their unique characteristics. In the present work, we focused on the syntheses, structures, and reactivities of such types of amine complexes, [NHC·BH 2 NH 3 ]X ((NHC = IPr (1,3-bis(2,6-diisopropylphenyl)imidazol-2-ylidene) and IMe (1,3-dimethylimidazol-2-ylidene); X = Cl, I, OTf). We have developed a synthetic method to access NHC·BH 2 NH 2 through the reaction of NaH with [IPr·BH 2 NH 3 ]I, which was synthesized by the reaction of IPr·BH 2 I with NH 3 . As a Lewis base, NHC·BH 2 NH 2 could further react with HCl or HOTf to produce the corresponding salts of [IPr·BH 2 NH 3 ] + . IPr·BH 2 NH 2 BH 2 X (X = Cl, I) were synthesized by the reaction of HCl/I 2 with IPr·BH 2 NH 2 BH 3 and then converted to [IPr·BH 2 NH 2 BH 2 ·IPr]X (X = Cl, I) by reacting with IPr. The IMe-coordinated boranes reacted quite similarly. The preliminary results revealed that the introduction of the NHC molecule has a considerable impact on the solubility and reactivities of aminoboranes.