Synthesis of [Ni(η2-CH2C6H4R-4){PPh(CH2CH2PPh2)2}]+ (R = H, Me or MeO) and protonation reactions with HCl

The complexes [Ni(η2-CH2C6H4R-4)(triphos)]BPh4 {R = H, Me or MeO; triphos = PhP(CH2CH2PPh2)2} have been prepared and structurally characterised. These complexes react with anhydrous HCl in MeCN to form [NiCl(triphos)]+ and the substituted toluene. Kinetic studies suggest a mechanism involving initial rapid protonation at the nickel, followed by intramolecular proton migration from nickel to carbon to yield the products.