Anion effect in the diastereoselective formation of bischelated Ni(II) complexes with a novel, chiral phosphine derived from 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU).

With the new chiral phosphine ligand DBUP, obtained from DBU and Ph(2)PCl, a remarkable anion effect was observed on the diastereoselective formation of the bischelated complexes [Ni(DBUP)(2)](X)(n) (X = Cl, Br, n = 2; X = NiCl(4), n = 1), which are active ethylene oligomerization catalyst precursors.