Donor-free 9,10-dihydro-9,10-dialuminaanthracenes.

Despite their promising potential, , as ditopic, cooperatively binding Lewis acids, 9,10-dihydro-9,10-dialuminaanthracenes (DAA-R; R: terminal Al-bonded substituent) have remained unexplored for long due to the challenges in synthesizing the ligand-free species. We demonstrate that DAA-Me is accessible the reaction of 1,2-(MeSn)CH with AlMe, producing volatile SnMe as the sole byproduct. In non-coordinating solvents and in the solid state, DAA-Me exists as a dimer (DAA-Me). Treatment of (DAA-Me) with 4 equiv. AlBr cleaves the dimer, leads to quantitative Me/Br exchange, and forms the double AlBr adduct DAA-Br·(AlBr). Removal of AlBr with 2,2'-bipyridine gives free DAA-Br, which also dimerizes in the absence of bases to form (DAA-Br). (DAA-Me) and (DAA-Br) readily react with mono- (, pyridine) or ditopic Lewis bases (, potassium pyrazolide) to afford -diadducts or triptycene-type frameworks. Upon addition of [BuN]Br, DAA-Br·(AlBr) undergoes selective cleavage of Al-C bonds to produce the Br chelate complex of 1,2-(BrAl)CH, a valuable synthon for 1,2-dideprotonated benzenes.