Cleavage of C(sp)-F Bonds in Trifluoromethylarenes Using a Bis(NHC)nickel(0) Complex.

The first example of the oxidative addition of a C(sp)-F bond in trifluoromethylarenes to a nickel(0) complex is described. A nickel(0) complex that bears two -heterocyclic carbene (NHC) ligands of low steric demand is able to cleave C(sp)-F bonds of trifluoromethylarenes to afford the corresponding -difluorobenzyl nickel(II) fluoride complexes. Isolation and characterization studies suggested that the cleavage of the C(sp)-F bond proceeds via an η-arene nickel(0) complex. Taking advantage of the reactivity of these nickel(II) fluoride complexes, we developed a catalytic hydrodefluorination of trifluoromethylarenes using hydrosilanes. A computational study indicated that the electron-rich nickel(0) center supported by two relatively small NHC ligands cleaves the C(sp)-F bond via a -S2' mechanism.