Catalytic olefin oligomerisation activity of a series of trialkyl- and triphenylphosphine derivatives of the nickel (II) complexes of 4-thioxo-2-pentanoate and 2,4-pentanedithionate
作者:G.A. Foulds、A.M.A. Bennet、M.L. Niven、D.A. Thornton、K.J. Cavell、S. Desjardins、E.J. Peacock
DOI:10.1016/0304-5102(93)e0191-i
日期:1994.2
A series of complexes of the type [Ni(L)(PR3)X] and [Ni(L)(Ph2P(CH2)(n)27PPh2)]BPh4 (where L = 4-thioxo-2-pentanoate (sacac); R = ethyl (Et), R = n-butyl((n)Bu); X = Cl, Br, n = 1 or 2; where L = 2,4-pentanedithionate (sacsac); R = methyl (Me), ethyl (Et), cyclohexyl (Cy) and phenyl (Ph); X = Cl, Br) has been prepared. The complex [Ni (sacac) (P(n)Bu3) Cl] is extremely labile. However, it could be prepared using ultrasound and identified by NMR. Attempts to recrystallize the complex lead to disproportionation. Several of the complexes were found to be active oligomerisation catalysts when tested for the oligomerisation of propene and 1-hexene. Factors that have been investigated are the effect of changing the Lewis acid co-catalyst, phosphine, chelating ligand (L) and halogen on the oligomerisation reaction. It is found that the phosphine ligand influences both the activity and selectivity of the oligomerisation reaction, whilst changing the thio ligand has a marked effect on catalyst activity only. In addition, the crystal structure of [Ni(C5H7OS) (P(C2H5)3)Cl] has been determined. Crystals of [Ni(C5H7OS)(P(C2H5)3)Cl] are monoclinic, P2(1)/n with a=7.644(4), b=18.005(8), c=11.021 (3) angstrom, beta=96.17(3)degrees V=1508(5) angstrom3, Z=4. The structure was solved using a Patterson map and refined to R=0.056 for 2227 reflections and 162 parameters. The Ni atom has square-planar coordination with Cl trans to the sulphur atom of the sacac ligand.