Synthesis and Characterization of NiII and PdII Complexes Bearing N,N,S Tridentate Ligands and Their Catalytic Properties for Norbornene Polymerization

Abstract

AbstractA series of new N,N,S tridentate nickel(II) complexes [(ArN = CHC6H4NPh‐2‐SPh)NiBr] (Ar = 2,6‐diisopropylphenyl, 1; Ar = 2,6‐dimethylphenyl, 2; Ar = Ph, 3) and palladium(II) complexes [(ArN = CHC6H4NPh‐2‐SPh)PdCH3] (Ar = 2,6‐diisopropylphenyl, 4; Ar = 2,6‐dimethylphenyl, 5; Ar = Ph, 6) were synthesized and characterized. X‐ray diffraction analyses of the single‐crystal structures revealed that tridentate complexes 1, 2, 4, 5, and 6 featured a distorted square‐planar coordination of the central metal. Compared to the bidentate metal complexes bearing anilido–imine ligands, the N,N,S tridentate metal complexes showed better stability. In the presence of methylaluminoxane (MAO), nickel complexes 1–3 showed moderate activity toward ethylene oligomerization at atmosphere pressure, but the palladium complexes were inactive. However, the nickel complexes exhibited high activity up to 8.20 × 106 g/(mol of Ni) h and palladium complexes showed very high activity up to 2.68 × 108 g/(mol of Pd) h toward norbornene polymerization with MAO as cocatalyst. The obtained polynorbornenes are vinylic addition polymers with high molecular weights. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)