Synthesis Of Bis(?-diimine) Ni(?),Pd(?) With Different Electronic Effects And Spatial Configuration And Their Catalystic Copolymerization For Nobornene

In this paper,a series of spatial configuration bis??-diimine?Ni?II?Ni?L?₂Br₂ {Ni?L1?₂Br₂-Ni?L4?₂Br₂} and Pd?II?Pd?L?₂Br₂{Pd?L1?₂Br₂-Pd?L4?₂Br₂} were synthesized by the ?-diimine ligands?L1-L4?containing different electronic effect and spatial configuration,9,10-dihydro-9,10-ethanoanthracene-11,12-di?Ar?imine?Ar = p-PhCH3,L1;Ar = p-PhCl,L2;Ar = p-PhCF3,L3;Ar = p-PhNO2,L4.?.Ni?L?₂Br₂ and Pd?L?₂Br₂ were tested for nobornene?NB?homopolymerization and copolymerization of NB with 1-alkene,n-butyl methacrylate?BMA?and methyl methacrylate?MMA?.The effects of electronic effect,polymerization conditions and monomer feed ratio on the polymerization and the properties of copolymers were investigated.The molecular structures of Ni?L?₂Br₂ were determined by X-ray crystallography.The complexes have a six-coordinate pesudooctahedral geometry with bis?a-diimine?and two bromide ligands around the nickel center.Ni?L1?₂Br₂-Ni?L3?₂Br₂ were tested for NB polymerization after activation with B?C6F5?3.The polymerization at 120 oC with NB/Ni ratio at 5000/1 and B/Ni ratio at 20/1 were the most effective conditions,the catalytic activity reached to 107 gpolymer/molNi·h for homopolymerization and 105 gpolymer/molNi·h for copolymerization.The activities enhanced with the increase of the electron withdrawing effect,and shown the rule of the catalysts with Ni?L3?₂Br₂ > Ni?L2?₂Br₂ > Ni?L1?₂Br₂.Meanwhile,the catalytic activity decreased with the increase for the feed ratio and alkene chain length,followed in the order of 1-hexene > 1-octene.The 1-alkene contents in copolymers could be controlled up to 6-27 % by varying the 1-alkene monomer feed ratios from 10 to 90 %.And all copolymers exhibited high molecular weight?up to 105 g/mol?,good thermal stability?Td > 375 oC?and good transparency?T > 75 %?.Ni?L4?₂Br₂ with strong electron-withdrawing group was applied to the homopolymerization and copolymerization of NB and butyl methacrylate?BMA?combined with B?C6F5?3.The results indicated that the catalyst exhibited high catalytic activity and thermal stability.And the catalyst had low oxygen affinity that could catalyze the BMA homopolymerization.The catalytic activity decreased with the increase of the feed ratio.The BMA contents in copolymers could be controlled up to 6.0–78.7 % by varying the BMA monomer feed ratios from 10 to 90 %.All copolymers exhibited narrow molecular weight distribution?Mw/Mn = 1.1-1.4?,good thermal stability?Td > 390 oC?,good mechanical properties and transparency?T > 85 %?.The reactivity ratios of the NB and BMA monomers by the Kelen-Tüd?s method were determined to be rNB = 1.81,rBMA = 0.13,respectively,which indicated the random copolymerization of NB with BMA.Pd?L1?₂Br₂-Pd?L4?₂Br₂ were tested for the copolymerization of NB with MMA after activation with MAO.The copolymers were confirmed to be block copolymer by TGA.The activity was related to the electronic effect of the substituent,the catalytic activity of Pd?L4?₂Br₂ bearing strong electron-withdrawing group-NO2 achieved the highest activity with 8.36×104 gpolymer/molPd·h.And the catalytic activity decreased with the increase of the NB feed ratio.The obtained copolymers exhibited high molecular weight?2.82-4.95×104 g/mol?,narrow molecular weight distribution?1.1-1.5?.And the copolymers had good solubility and could be dissolved in most of the organic solvent.