Synthesis, characterization and catalytic activity of nickel NHC complexes

Several new cyclopentadienylnickel complexes were synthesized and characterized. All the complexes exhibited catalytic activity in Suzuki Miyaura cross-coupling reaction with conversion rates from 10 to 80% and very high selectivity. The catalytic activity of the complexes strongly depended on their composition and structure. It was shown that ionic complexes are better catalysts than their covalent analogues; increased electron density in the cyclopentadienyl ligand improved their catalytic activity; bromide complexes provided better results than chloride ones. Two CpNi(NHC)CI complexes were tested as initiators in the oligomerization of ethyl acetate carbene confirming our earlier observation that N-heterocyclic carbene from the catalyst precursor was incorporated into the oligomer chain. (C) 2017 Elsevier B.V. All rights reserved.