Formation and nature of catalysts based on nickel(0) phosphine complexes active in lower alkene dimerization and oligomerization

The catalytic properties and formation mechanism of alkene dimerization-active complexes in systems based on Ni(PPh₃)₄ and boron trifluoride etherate are considered. The nature of the modifying action of Brønsted acids on the properties of metal complex catalysts for propylene dimerization is reported. The interaction between Ni(PPh₃)₄ and BF₃ · OEt₂ is influenced by water. Depending on the water concentration, the reaction can proceed via formally one-electron oxidation to yield cationic Ni(I) complexes or via two-electron oxidation to yield Ni(II) hydrides. The catalytically active species in alkene dimerization and oligomerization in these systems are Ni(II) hydrido complexes.