PivaloNi: A Stable, Dicationic "Naked Nickel" Precursor for Coordination Chemistry and Catalysis

Abstract

In this study, we report the isolation, characterization, and reactivity of a new dicationic Ni II compound supported by pivalonitrile ligands, with the stoichiometry [Ni(tBuCN)4(OH2)2][BF4]2, abbreviated as pivaloNi. We show that the pivalonitrile ligands are labile and can be displaced by solvent molecules like tetrahydrofuran or acetonitrile. Surprisingly, pivaloNi was found to be more stable to hydrolysis compared to the related hexakisacetonitrilenickel(II) compound. In accordance with its lability, pivaloNi can be used as an efficient Ni II precursor for coordination chemistry, as shown by a variety of ligand substitution reactions. In addition, we also show its utility as a precursor for several cross-coupling reactions, despite having no obvious transmetalation sites. This work introduces a bench-stable but labile Ni II precursor to the synthetic chemist's toolkit.