Synthesis of HC[(CBut)(NAr)]2Al (Ar=2,6-Pri2C6H3) and its reaction with isocyanides, a bulky azide, and H2O

The reaction of H2C[(CBut)(2)(NAr)(2)] (Ar = 2,6-(Pr2C6H3)-C-i) with AlEt3 in refluxing toluene gave HC[(CBut)(2)(NAr)(2)]AlEt2 (1) in high yield. Treatment of 1 with 2 equiv of iodine in toluene yielded HC[(CBut)(2)(NAr)(2)]AlI2 (2). Reduction of 2 with potassium resulted in the formation of the tert-butyl-substituted beta-diketiminato aluminum(I) compound HC[(CBut)(2)(NAr)(2)]Al (3). Reactions of 3 with isocyanides, H2O, and a bulky terphenyl azide were investigated. 3 reacted with 2 equiv of CNAr to give two C-C coupling products: in dilute solution, the C-C coupling of two CNAr molecules was followed by the C-H activation of one of the CHMe2 groups on the Ar ring of CNAr, while in concentrated solution or in the presence of an excess of the isocyanide, the coupling was accompanied by cleavage of one of the C-N bonds of the ligand backbone. Reaction of 3 with the bulky azide 2,6-Ar2C6H3N3 yielded the C-H activation product 6. Hydrolysis of 3 in toluene afforded a hydroxyaluminum hydride. Compounds 1 and 3-5 were characterized by X-ray single-crystal analysis.