Dioxygen Activation and Substrate Oxygenation by a <i>p</i>-Nitrothiophenolatonickel Complex: Unique Effects of an Acetonitrile Solvent and the <i>p</i>-Nitro Group of the Ligand

The nickel(II) complex [Ni(TpMe2) (SC6H4NO2)] [1a; TpMe2 = hydrotris(3,5-dimethylpyrazol-1-yl)borate] reacts with O2 to form the ligand oxygenation product ArSO2– in MeCN, and also 1a catalyzes the oxygenation of external substrates such as triphenylphosphine. The reactivity may correlate to the unique quinoid-like resonance structure of the thiophenolate ligand. The structure is stabilized by a p-nitro group and induced by coordination of MeCN.