Catalysis of dimerization and oligomerization reactions of lower alkenes by systems based on Ni(PPh3)2(C2H4) and Ni(PPh3)nCl (n = 2 or 3)

The catalytic characteristics of the individual complex Ni(PPh 3 ) 2 (C 2 H 4 ) and Ni(PPh 3 ) n Cl ( n = 2 or 3) and those of systems based on these complexes in combination with Brönsted and Lewis acids in ethylene and propylene oligomerization have been determined. A correlation between the BF 3 · OEt 2 solution storage time and the catalytic properties of the nickel systems has been established for the reactions of the lower alkenes. The observed increase in the turnover frequency and turnover number of the catalyst is due to the increase in the Brörsted acid concentration as a result of irreversible conversions of BF 3 · OEt 2 caused by its interaction with impurity water in the solvent. The formation of the Ni(PPh 3 ) 2 (C 2 H 4 )-BF 3 · OEt 2 catalytic system in the presence of a substrate dramatically extends the system’s service life. The interaction of the nickel precursors with boron trifluoride etherate has been investigated using a complex of physical methods, and the main reactions yielding catalytically active species have been revealed.