Dialkylaluminium complexes derived from 1,8-diphenyl-3,6-dimethylcarbazole: a new sterically hindered monodentate ligand system

A new type of sterically hindered, monodentate ligand system based on the carbazolide frame is introduced. (1,8-diphenyl-3,6-dimethylcarbazolide)AlR2 (4, R=Me; 5, R=Et) complexes have been prepared by N-lithiation of the carbazole, followed by reaction with the appropriate dialkylaluminium chloride. Treatment of the dialkyl complexes 4 and 5 with B(C6F5)3 or [H(OEt2)2][B{3,5-(CF3)2C6H3}4] affords [LAlR]+ species followed by products arising from alkyl/ArF exchange. The cationic alkylaluminium species are found to oligomerise ethylene to C4C10 olefinic products.