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.