Accessing Pincer Bis(carbene) Ni(IV) Complexes from Ni(II) via Halogen and Halogen Surrogates

This communication describes the two-electron oxidation of (DIPPCCC)­NiX (DIPPCCC = bis­(diisopropylphenyl-benzimidazol-2-ylidene)­phenyl); X = Cl or Br) with halogen and halogen surrogates to form (DIPPCCC)­NiX3. These complexes represent a rare oxidation state of nickel, as well as an unprecedented reaction pathway to access these species through Br2 and halogen surrogate (benzyltrimethylammonium tribromide). The NiIV complexes have been characterized by a suite of spectroscopic techniques and can readily reduce to the NiII counterpart, allowing for cycling between the NiII/NiIV oxidation states.