The Selective Preparation of an Aluminum Oxide and Its Isomeric C−H-Activated Hydroxide

An aluminum oxide [LAlO]<sub>2</sub> (<b>1</b>) has been prepared by the oxidative addition of aluminum(I) monomer LAl (L = HC[(CMe)(NAr)]<sub>2</sub>, Ar = 2,6-<i>i</i>Pr<sub>2</sub>C<sub>6</sub>H<sub>3</sub>) with molecular oxygen. The short Al−O bonds in Al<sub>2</sub>(μ-O)<sub>2</sub> result in short Al···Al contacts and subsequent steric crowding of the Ar substituents from the two oriented L. <b>1</b> hydrolyzes to form [LAl(OH)]<sub>2</sub>(μ-O) (<b>2</b>). A C−H-activated aluminum hydroxide <b>4</b>, an isomer of <b>1</b>, however, is obtained by hydrolysis of the bulky aluminum amide <b>3</b> rather than by a conversion by high temperature treatment of <b>1</b>. This indicates selective preparation of isomers <b>1</b> and <b>4</b>.