A Ni σ-Borane Complex Bearing a Rigid Bidentate Borane/Phosphine Ligand: Boryl Complex Formation by Oxidative Dehydrochloroborylation and Catalytic Activity for Ethylene Polymerization.

While of interest, synthetically feasible access to boryl ligands and complexes remains limited, meaning such complexes remain underexploited in catalysis. For bidentate boryl ligands, oxidative addition of boranes to low-valent Ir or Pt are the only examples yet reported. As part of our interest in developing improved group 10 ethylene polymerization catalysts, we present here an optimized synthesis of a novel, rigid borane/phosphine ligand and its Ni σ-borane complex. From the latter, an unprecedented oxidative dehydrochloroborylation, to give a Ni boryl complex, was achieved. Furthermore, this new B/P ligand allowed the nickel-catalyzed polymerization of ethylene, which suggests that Ni σ-hydroborane complexes act as masked Ni boryl hydride reagents.