The selective oligomerization of butenes by nickel-based catalysts

The compounds Ni(sacsac)P(L1L2L3)X (sacsac = pentane-2,5-dithionato, Lj = alkyl or aryl, X = halogen) catalyse the oligomerization and isomerization of n-butenes at room temperature under autogeneous pressure. The oligomerization proceeds with high selectivity for dimers. The concentration of butene as a function of time is described by 1n (butene) = A exp (Bt) + C. The product selectivity and the parameters A, B and C are controlled by the choice of phosphine ligand.