beta-Diketinrinato Ni(II) bromide complexes were synthesized and used to catalyze isomerization and oligomerization of 1-hexene in the presence of methylalun-Linoxane (MAO). GC-MS and GC analysis confirmed that the products are mainly hexene isomers and dimer isomers. 3-Hexene isomers. trimers and higher oligomers were not detected. The results were ascribed to the configuration of the beta-diketiminato Ni(II) catalyst. The migation of the Ni atom from a secondary or tertiary carbon to another one along the alkyl chain of the Ni-alkyl intermediates is blocked by the coordination wedge of the beta-diketiminato ligands. However, the migration of the Ni atom from a primary carbon to the adjacent secondary or tertiary carbon is thermodynamically favored. (c) 2005 Elsevier B.V. All riahts reserved.