This paper describes the synthesis and characterization of trimethylaluminum (2a), dimethylaluminum (3a), and triphenylboron complexes (7) supported by functional amine-linked NHC ligands. The chemical reactivity studies with carbodiimide and isocyanate were preformed with 2a and 3a, illustrating the noninnocent nature in Al–carbene bonding. However, the boron–carbene interaction is quite robust against addition of these substrates even at higher temperature conditions. The subtle difference in chemical reactivity between aluminum and boron is attributed from the metal–carbene bond covalency. Development of the catalytic method for Suzuki–Miyaura coupling utilizing triphenylboron reagent supported by amino-NHC is also presented.

Dimeric zirconium benzyl and amide complexes supported by an imidazolone framework have been successfully synthesized and fully characterized. The amide complexes were found to be effective catalysts for intramolecular hydroamination of primary and secondary amines.

We have successfully expanded the library of amino-NHCs with varying substituents on the amine group, leading to insight about the instability of NHCs arising from the intermolecular interaction of the dangling amine side-arm. However, the pendant amine plays an important role with respect to the catalytic process, resuscitating the catalytic activity of unsaturated NHC's through a synergistic effect invoked by the secondary amine. This proof of concept allows us to expand the spectrum of catalysis to C-C, as well as C-B bond formation.

We have obtained boronium complexes upon reaction of an amino-NHC lithium bromide adduct with borane. Unexpectedly, the treatment of the boronium complexes with silver triflate led to the isolation of a bis-borane compound containing two chemically different boron centers. The bisborane and boronium complexes can interconvert via a fourmembered intermediate metallacycle consisting of a three-center, two-electron B-H-B bonding motif assisted by the pendant amine arm.