OLEFIN OLIGOMERIZATION WITH NICKEL PO CHELATE COMPLEXES

Various alpha-keto ylides were reacted in situ with (COD)2Ni and the solutions obtained were applied in ethylene oligomerization/polymerization. It could be shown that changes in substituents of the Arc PO chelate Part drastically influence the product distribution of the oligomers/polymers. In the case of MePh2PCHCOPh, EtPh2PCHCOPh, and CyPh2PCHCOPh, the maximum molecular weight occurs at about 2.8 (logarithm scale). However, in the case of nMenPh2PCHCOPh, it occurs at 3.3. The molecular-weight dispersions (M(w)BAR/M(n)BAR) increase in the following order: RPh2PCHCOPh: R = Me < R = Et < R = Cy < R = nMen In this way a handle via the Arc PO-ligand is given to tailor the steepness of the Schulz-Flory type distribution.