21. Silica-grafted Tris(neopentyl)aluminum: A Monomeric Aluminum Solid Co-Catalyst for Efficient Nickel-Catalyzed Ethene Dimerization
    Copéret, C.; Moroz, I.; Florian, P.; Viger Gravel, J.; Gordon, C. P.; Lesage, A.
    Angew. Chem. Int. Ed. 2020, 59, 16167-16172

A silica-supported monomeric alkylaluminum co-catalyst was prepared via Surface Organometallic Chemistry by contacting tris-(neopentyl)aluminum and partially dehydroxylated silica . This system, fully characterized by solid-state  27 Al NMR augmented by computational studies, efficiently activates ( n Bu 3 P) 2 NiCl 2  towards dimerization of ethene demonstrating comparable activity to previously reported dimeric diethylaluminum chloride supported on silica.  Three types of aluminum surface species have been identified: monografted tetracoordinated Al species as well as two types of bis-grafted Al species – tetra- and pentacoordinated. Of them, only the monografted Al species is proposed to be able to activate the  ( n Bu 3 P) 2 NiCl 2  complex and generate the active cationic species.

DOI : 10.1002/anie.202006285