Synthesis and Characterization of Nickel(II) and Palladium(II) Complexes based on Tridentate [N–NP] and [N–NS] Ligands and Their Applications in Norbornene Polymerization

The series of anilido-imine N – NP and N – NS tridentate nickel and palladium complexes [(ArNHC 6 H 4 CH═NPh-2-XPh)MCl] (X = PPh, Ar = 2,6-Me 2 C 6 H 3, M = Ni ( 2a ), X = PPh, Ar = 2,6-Et 2 C 6 H 3, M = Ni ( 2b ); X = PPh, Ar = 2,6- i -Pr 2 C 6 H 3, M = Ni ( 2c ); X = S, Ar = Ph, M = Ni ( 2d ); X = S, Ar = 2,6-Me 2 C 6 H 3, M = Ni ( 2e ); X = S, Ar = 2,6- i -Pr 2 C 6 H 3, M = Ni ( 2f ); X = PPh, Ar = 2,6-Me 2 C 6 H 3, M = Pd ( 3a ); X = PPh, Ar = 2,6-Et 2 C 6 H 3, M = Pd ( 3b ); X = PPh, Ar = 2,6- i -Pr 2 C 6 H 3, M = Pd ( 3c )) were synthesized. All the complexes were fully characterized by IR, NMR and elemental analyses. X-ray diffraction analyses on complexes 2a, c and 3a revealed an almost square-planar coordination of the central metal. After activation with methylaluminoxane (MAO), the nickel(II) complexes 2a – f can be used as catalysts for norbornene polymerization to produce vinyl addition type polynorbornene (PNB) with high catalytic activities, up to 5.82 × 10 7 g of PNB (mol of Ni) −1 h –1, while poor catalytic activities are found for the palladium complexes 3a – c.