Beschreibung:
<jats:title>Abstract</jats:title><jats:p>Abnormal N‐heterocyclic carbene (aNHC) based Ni(II) π‐allyl complexes (<jats:bold>3</jats:bold> and <jats:bold>4</jats:bold>) were synthesized starting from a Ni(0) precursor. These complexes were characterized by NMR spectroscopy, single‐crystal X‐ray crystallography (<jats:bold>4</jats:bold>) and elemental analysis data. The underlying mechanism for the formation of Ni(II) η<jats:sup>3</jats:sup>‐allyl complexes from a Ni(0) precursor on treatment with a free abnormal N‐heterocyclic carbene in absence of any external additive or oxidant was unraveled. Later, complex <jats:bold>3</jats:bold> was exposed to O<jats:sub>2</jats:sub> gas under ambient pressure resulting in molecular oxygen activation to form a μ‐hydroxo bridged Ni(II) dimer.</jats:p>