Isomerization of 1-Butene Catalyzed by (η6-Arene)NiR2. A Very Active Homogeneous Catalyst System

Article abstract of DOI:10.1021/ja00268a048

(η⁶-Arene)NiR2 (R = SiCl3, SiF3, C6F5) complexes exhibit very high catalytic activity for the isomerization of 1-butene, especially in bromobenzene solution.The isomerization is generally first order in both 1-butene and Ni complex.The catalytic activity decreases in the order SiCl3 > SiF3 > C6F5.The reaction rate in toluene solution increases with increasing 1-butene concentration below a ratio of 1-C4H8/Ni = 100 but decreases at higher ratios apparently due to induced decomposition of the Ni complex.However, the rate is not adversely affected by high 1-C4H8 concentration in bromobenzene solution.The ratio of cis-2-butene to the trans isomer is also dependent on solvent, suggesting that an important step in the mechanism is the involvement of solvent in the catalytic cycle.The reaction of ethylene with (η⁶-arene)Ni(SiCl3)2 gives vinyltrichlorosilane and ethyltrichlorosilane.A mechanism is proposed which involves the intermediacy of nickel hydride species generated by the insertion of 1-butene into the Ni-R bond followed by β-hydride elimination.