Phosphine (oxide)‐(thio) phenolate palladium complexes: Synthesis, characterization and (co)polymerization of norbornene

A series of palladium complexes ( 2a–2g ) ( 2a : [6‐ t Bu‐2‐PPh 2 ‐C 6 H 3 O]PdMe(Py); 2b : [6‐C 6 F 5 –2‐PPh 2 ‐C 6 H 3 O]PdMe(Py); 2c : [6‐ t Bu‐2‐PPh t Bu‐C 6 H 3 O]PdMe(Py); 2d : [2‐PPh t Bu‐C 6 H 4 O] PdMe(Py); 2e : [6‐SiMe 3 –2‐PPh 2 ‐C 6 H 3 O]PdMe(Py); 2f : [2‐ t Bu‐6‐(Ph 2 P=O)‐C 6 H 3 O]PdMe(Py); 2g : [6‐SiMe 3 –2‐(Ph 2 P=O)‐C 6 H 3 S]PdMe(Py)) bearing phosphine (oxide)‐(thio) phenolate ligand have been efficiently synthesized and characterized. The solid‐state structures of complexes 2d , 2f and 2g have been further confirmed by single‐crystal X‐ray diffraction, which revealed a square‐planar geometry of palladium center. In the presence of B(C 6 F 5 ) 3 , these complexes can be used as catalysts to polymerize norbornene (NB) with relatively high yields, producing vinyl‐addition polymers. Interestingly, 2a /B(C 6 F 5 ) 3 system catalyzed the polymerization of NB in living polymerization manner at high temperature (polydispersity index 1.07, M n up to 1.5 × 10 4 ). The co‐polymerization of NB and polar monomers was also studied using catalysts 2a and 2f . All the obtained co‐polymers could dissolve in common solvent.