Synthesis of nickel and palladium complexes with diarylamido-based unsymmetrical pincer ligands and application for norbornene polymerization

• Published in: Dalton transactions : an international journal of inorganic chemistry 2019-01, Vol.48 (2), p.69-617
• Main Authors: Liu, Hui, Yuan, Haibin, Shi, Xiaochao
• Format: Article
• Language: English
• Subjects: Catalysis; Catalytic activity; Copolymerization; Crystallography; Ligands; Nickel; Palladium; Polymerization
• ISSN: 1477-9226; 1477-9234
• DOI: 10.1039/c8dt04413a

A set of diarylamido-based unsymmetrical [PNN ox ] pincer ligands containing a chiral oxazoline ring have been synthesized and their nickel and palladium complexes [(2-PPh 2 (R 1 )ArN(R 1 )Ar-2-(R)oxazoline)MCl] (R 1 = 4-H, R = ( S )-4- i Pr, M = Pd ( Pd1 ); R 1 = 4-H, R = ( S )-4-Bn, M = Pd ( Pd2 ); R 1 = 4-H, R = ( S )-4-Ph, M = Pd ( Pd3 ); R 1 = 4-Me, R = ( S )-4-Bn, M = Pd ( Pd4 ); R 1 = 4-Me, R = ( S )-4-Ph, M = Pd ( Pd5 ); R 1 = 4-H, R = 4-Me 2 , M = Pd ( Pd6 ); R 1 = 4-H, R = Benzo[ d ]-, M = Pd ( Pd7 ); R 1 = 4-H, R = ( S )-4-Bn, M = Ni ( Ni1 ); R 1 = 4-H, R = ( S )-4-Ph, M = Ni ( Ni2 ); R 1 = 4-Me, R = ( S )-4-Bn, M = Ni ( Ni3 ); R 1 = 4-Me, R = ( S )-4-Ph, M = Pd ( Ni4 )) were tested to show high catalytic activities for polymerization of norbornene. After activation of methylaluminoxane (MAO), all the nickel and palladium complexes could catalyze the polymerization of norbornene to yield vinyl-type polymers with activities up to 40.3 × 10 5 g of PNB (mol of Pd) −1 h −1 . The copolymerization of norbornene with functional norbornene comonomers was also investigated by catalyst Pd2 , accompanied by decreased catalytic activity and low incorporation of functional comonomers. Nickel and palladium complexes chelating diarylamido-based unsymmetrical [PNN ox ] pincer ligands have been synthesized and used as catalysts for norbornene polymerization with activities up to 40.3 × 10 5 g of PNB (mol of Pd) −1 h −1 upon the activation of methylaluminoxane (MAO).