A Constraining and Redox-Active Aluminum Species With Diverse Reactivity

This work reports the synthesis, full characterization, and multifaceted reactivity of a highly reactive aluminum complex (2·Et₂O) supported by a sterically hindered, redox-active pincer ligand. Characterization by X-ray crystallography and spectroscopic methods confirmed its molecular structure, while Gutmann-Beckett studies and calculated fluoride ion affinity quantified its significant Lewis acidity. The reactivity profile of 2·Et₂O is remarkably diverse: it undergoes facile photoinduced species formation, activates the O─H bond via metal-ligand cooperative heterolytic cleavage, and engages in redox reactions with substrates such as Ph₃CCl and PhSSPh. Most notably, 2·Et₂O demonstrates distinct selectivity in activating the C─I bond of iodoalkanes. This process proceeds via a kinetically favored or cooperative pathway, leading to alkyl group transfer to the ligand, rather than the thermodynamically preferred σ-bond oxidative addition at the aluminum center. This study highlights how the synergy between an Al(III) center and a non-innocent pincer ligand can unlock unique reaction manifolds, expanding the potential of main-group elements in stoichiometric bond activation.