A novel approach for the stabilization and structural characterization of group 13 organometallic hydroxides: The way to well defined crystalline methylalumoxanes

The controlled hydrolysis products of R3M (M = Al, Ga; R = Mes, Ph, Me) have been found to be stabilized by deprotonation reactions using alkyllithium reagents. (Mes(3)Ga . OHLi). 3THF (1) and (Mes(3)Al . OHLi).-3THF (3) were synthesized by the reaction of LiOH with Mes(3)Ga and Mes(3)Al, respectively. The hydroxides, (R-2- MOH)(n), resulting from the reaction of water and R3M were deprotonated with RLi (R = Bu-t, Me) to give (Mes(2)GaOLi)(2) . 4THF (2), (Mes(2)AlOLi)(2) . 4THF (4), (Ph2AlOLi)(3) . 6THF (5), and (Me2AlOLi)(4) . 7THF . LiCl (6). The molecular structures of compounds 1, 2, 4, 5, and 6 have been determined by X-ray structure analysis. Whereas 2 undergoes metathesis reactions, compounds 1, 3, 4, 5, and 6 are stable at room temperature. Compound 6 is the first structurally characterized intermediate on the pathway to cocatalytically active methylalumoxane used in metallocene catalyzed olefin polymerization reactions. Moreover, it represents the first structurally characterized alumoxane stabilized by a separated cation.