Nickel Complexes Involved in the Isomerization of 2-Methyl-3-butenenitrile

The nickel(0) fragment [(P−P)Ni], where (P−P) = dcype (1,2-bis(dicyclohexylphosphino)ethane) or dtbpe (1,2-bis(di- tert -butylphosphino)ethane), reacts with the cyano-olefins involved in the isomerization process of 2-methyl-3-butenenitrile (2M3BN), producing the corresponding complex [(P−P)Ni(η 2 - C,C -cyano-olefin)]. In the case of 2M3BN and 3-pentenenitrile (3PN), the π-methylallyl metal complex was observed in solution. All of the intermediates in the catalytic cycle were detected and characterized by heteronuclear NMR spectroscopy; some of these were also characterized by single-crystal X-ray diffraction studies. The initial catalytic behavior of this system for the isomerization of 2M3BN was studied also.