Theoretical study of FMO adjusted C-H cleavage and oxidative addition in nickel catalysed C-H arylation

Nickel catalysis has recently emerged as an important addition to the suite of transition metal-catalysed C-H bond functionalization methods. Here we report density functional theory calculations to elucidate the mechanism of Ni(II)-catalysed C-H arylation with a diaryliodonium salt or a phenyliodide. The effect of the choice of oxidant on the order of oxidative addition and C-H bond cleavage is investigated. When the active catalyst is oxidized by the diaryliodonium salt oxidant, C-H bond cleavage occurs to give an alkyl-aryl-Ni (IV) species. Conversely, the relatively weak oxidant phenyliodide leads to an alternative reaction sequence. The active catalyst first undergoes C-H bond cleavage, followed by oxidative addition of the phenyliodide to give a Ni(IV) species. Frontier molecular orbital analysis demonstrates that the reaction sequence of oxidative addition and C-H bond cleavage is determined by the unoccupied C-aryl-I bond antibonding orbital level of the oxidant.