Outer‐Sphere Reactivity Shift of Secondary Phosphine Oxide‐Based Nickel Complexes: From Ethylene Hydrophosphinylation to Oligomerization

A new dimension for secondary phosphine oxide (SPOs) ligands is described in this article. Demonstrated on original π‐allylic nickel structures, these self‐assembled complexes trigger catalytic hydrophosphinylation reactions. Addition of a Lewis acid B(C6F5)3 switches the reactivity towards migratory insertion and thus ethylene oligomerization through an unprecedented outer‐sphere interaction with the coordinated SPO ligand. NMR experiments and X‐ray analyses allowed for the observation of the formation of zwitterionic active species as well as their degradation pathway. On the outer sphere: A new dimension for secondary phosphine oxide (SPOs) ligands is described in this article. Demonstrated on original π‐allylic nickel structures, these self‐assembled complexes trigger catalytic hydrophosphinylation reactions. Addition of a Lewis acid B(C6F5)3 switches the reactivity towards migratory insertion and thus ethylene oligomerization through an unprecedented outer‐sphere interaction with the coordinated SPO ligand.