Metal-Free Dehydrogenation of Amine-Boranes by Tunable N-Heterocyclic Iminoboranes

We report the synthesis of structurally tunable boron complexes supported by N-heterocyclic imine ligands IPr=N-BR₂ (IPr=[(HCNDipp)₂ C], Dipp=2,6-iPr₂ C₆ H₃ , R=Cl and/or Ph) that have the ability to abstract dihydrogen from amine-boranes, and instigate their dehydrocoupling. In one instance, mild heating of the hydrogen addition product IPr=NH-B(Ph)HCl releases H₂ to regenerate the starting N-heterocyclic iminoborane; accordingly IPr=N-B(Ph)Cl can be used as a metal-free catalyst to promote the dehydrocoupling of MeNH₂ ⋅BH₃ to yield N-methylaminoborane oligomers [MeNH-BH₂ ]_x .