Unusual Reactivity of Molecular Oxygen with π-Allylnickel(N-heterocyclic carbene) Chloride Complexes

One-pot preparation and characterization of the first reported nickel(II) complexes containing a single imidazol-2-ylidene ligand are reported. Subsequent treatment of these complexes with molecular oxygen at room temperature results in rapid formation of a mu-hydroxo dimer and alpha,beta-unsaturated carbonyl compounds. Mechanistic investigations indicate that this reaction proceeds via reversible oxygen binding followed by rate-limiting decomposition of the resulting metal-oxygen species.