A Lewis Base‐Free Trialumane: Enhanced Electrophilicity Based on Consecutive Vacant Orbitals Over Three Aluminum Atoms

Abstract A Lewis base‐free trialumane having a 2,4,6‐triisopropylphenyl (Tip) substituent was synthesized by a reaction of alumanyl anion with TipAlBr 2 . The structure, bonding, and electronic properties of the Tip‐substituted trialumane were estimated by NMR spectra, X‐ray crystallographic analysis, DFT calculations, X‐ray photoelectron spectra, and electrochemical study to reveal its two consecutive Al─Al covalent bonds and overlapped vacant orbitals of three Al atoms. Chemical reduction of Tip‐substituted trialumane gave a series of alumanyl anions via the cleavage of the Al─Al bonds. This study shows the low‐lying characteristic LUMO that consists of vacant orbitals of three Al atoms in the base‐free trialumane.