Aryl-Fluoride Bond-Forming Reductive Elimination from Nickel(IV) Centers.

The treatment of pyridine- and pyrazole-ligated Ni σ-aryl complexes with Selectfluor results in C(sp)-F bond formation under mild conditions. With appropriate design of supporting ligands, diamagnetic Ni σ-aryl fluoride intermediates can be detected spectroscopically and/or isolated during these transformations. These studies demonstrate for the first time that Ni σ-aryl fluoride complexes participate in challenging C(sp)-F bond-forming reductive elimination to yield aryl fluoride products.

Nickel(IV)-Catalyzed C-H Trifluoromethylation of (Hetero)arenes.

This Article describes the development of a stable Ni complex that mediates C(sp)-H trifluoromethylation reactions. This reactivity is first demonstrated stoichiometrically and then successfully translated to a Ni-catalyzed C-H trifluoromethylation of electron-rich arene and heteroarene substrates. Both experimental and computational mechanistic studies support a radical chain pathway involving Ni, Ni, and Ni intermediates.

Carbon-Carbon Bond-Forming Reductive Elimination from Isolated Nickel(III) Complexes.

This manuscript describes the design, synthesis, characterization, and reactivity studies of organometallic Ni complexes of general structure TpNi(R)(R) (Tp = tris(pyrazolyl)borate). With appropriate selection of the R and R ligands, the complexes are stable at room temperature and can be characterized by cyclic voltammetry, EPR spectroscopy, and X-ray crystallography. Upon heating, many of these Ni compounds undergo C(sp)-C(sp) or C(sp)-C(sp) bond-forming reactions that are challenging at lower oxidation states of nickel.