Dimerization of Ethylene by Nickel Phosphino–Borate Complexes

Trifluoroborate-functionalized phosphine ligands react with a variety of nickel(II) precursors to cleanly yield a number of κ2(P,F)-bound nickel complexes, which were characterized crystallographically. In comparison to related palladium complexes, ancillary ligands in the nickel complexes were observed to be generally more weakly bound, and the trifluoroborate ligands were more easily displaced by coordinating solvents that did not cause a similar displacement in a related palladium system. Such weaker ligand coordination resulted in a much faster dimerization of ethylene. Experiments conducted under constant ethylene pressure saw the suppression of the isomerization of 1-butene observed in related palladium complexes; higher oligomers were also generated under such conditions.