Ambiphilic Ligand Stabilization of Aluminum(I) Fragments: Halides, Cations, and a Hydride.

Z-type ligands have been highly successful in stabilizing transition-metal fragments in unique coordination geometries and in enabling novel reactivities. However, examples of the use of these ligands in stabilizing elusive main-group metal fragments are scarce. In this study, we present the stabilization of aluminum (I) halides by an ambiphilic tris(phosphine)borane ligand. Unlocking unprecedented coordination chemistry at aluminum, the unique electronic structure of the novel compounds is analyzed in detail experimentally and computationally. Successful post-functionalization via coordination of Lewis bases to the Al atom enables isolation of elusive Al cations with the metal in a low redox state. In addition, the Al(I)Br transfer onto 2,2'-bipyridine ligands is presented.