The Pd(II) complex [PdCl2(1)] [1 = ({oxazolin-2-yl}methyl)diphenylphosphine] was obtained by the 1 : 1 reaction of 1 with [PdCl2(NCPh)2]. Although this neutral complex is stable in the solid-state and in solution, it reacts with the dinuclear complex [CoCl2(μ-1)]2 to afford the heterometallic zwitterionic complex [{PdCl(1)}+(μ-1)(CoCl3)−] (2). Under inert atmosphere, two equivalents of 1 reacted with [NiCl2(dme)] to give trans-[NiCl2(1)2] (3) in CH2Cl2 but cis-[NiCl2(1)2] (4) in CHCl3. When the latter reaction was performed in air, trans-[NiCl2(5)2] (6) [5 = ({oxazolin-2-yl}methyl)diphenylphosphine oxide] was obtained. All metal complexes, 2, 3, 4 and 6, have been structurally characterized by X-ray diffraction. Complexes 3, 4 and 6 have been evaluated as precatalysts for ethylene oligomerisation in the presence of AlEtCl2 as cocatalyst. Complexes 3 and 6 yielded a turnover frequency (TOF) of 60 700 and 62 600 mol of C2H4/((mol of Ni)·h), respectively, in the presence of 10 equiv. of AlEtCl2. In the presence of only 6 equiv. of cocatalyst, these Ni complexes yielded TOF values of 41 500 and 58 000 mol of C2H4/((mol of Ni)·h), respectively.
