The cyclocopolymerization of 1,6-heptadiene （HPD） with ethylene （E） by a series of half-sandwich scandium alkyl catalysts bearing various auxiliary ligands have been examined. Significant ligand influence on the c...The cyclocopolymerization of 1,6-heptadiene （HPD） with ethylene （E） by a series of half-sandwich scandium alkyl catalysts bearing various auxiliary ligands have been examined. Significant ligand influence on the copolymerization activity and selectivity was observed. In combination with one equivalent of [Ph3C][B（C6F5）4], the half-sandwich scandium dialkyl complexes bearing a Lewis base THF （1） or an NHC side arm （2） yielded the copolymer products together with cross-linked polymers in the copolymerization of HPD with ethylene. In contrast, the THF-free complexes Cp＇Sc（CH2C6H4NMe2-o）2 （3： Cp＇ = C5H5; 4： Cp＇ = CsMe4SiMe3） and the phosphine oxide side-arm containing complex （C5Me4SiMe2CH2（O）PPh2）Sc（CH2SiM%）2 （5） showed excellent activity and selectivity for the cyclocopolymerization reaction, without giving cross-linked products. The 1H and 13C NMR analyses revealed that the resulting copolymers consist of E-E sequences and six-membered ring methylene-1,3-cyclohexane （MCH） and five-membered ring ethylene-1,2-cyclopentane （ECP） units. The HPD content in the co- polymer products could be easily controlled by changing the feeding amount of HPD under 1 atm of ethylene.展开更多
基金supported by Grant-in-aid for Scientific Research (B) (24350030 to M.N.)a Grant-in-Aid for Scientific Research (S) ( 21225004 to Z.H.) from JSPS+1 种基金the National Natural Science Foundation of China (21204008)the Fundamental Research Funds for the Central Universities (DUT12RC(3)94)
文摘The cyclocopolymerization of 1,6-heptadiene （HPD） with ethylene （E） by a series of half-sandwich scandium alkyl catalysts bearing various auxiliary ligands have been examined. Significant ligand influence on the copolymerization activity and selectivity was observed. In combination with one equivalent of [Ph3C][B（C6F5）4], the half-sandwich scandium dialkyl complexes bearing a Lewis base THF （1） or an NHC side arm （2） yielded the copolymer products together with cross-linked polymers in the copolymerization of HPD with ethylene. In contrast, the THF-free complexes Cp＇Sc（CH2C6H4NMe2-o）2 （3： Cp＇ = C5H5; 4： Cp＇ = CsMe4SiMe3） and the phosphine oxide side-arm containing complex （C5Me4SiMe2CH2（O）PPh2）Sc（CH2SiM%）2 （5） showed excellent activity and selectivity for the cyclocopolymerization reaction, without giving cross-linked products. The 1H and 13C NMR analyses revealed that the resulting copolymers consist of E-E sequences and six-membered ring methylene-1,3-cyclohexane （MCH） and five-membered ring ethylene-1,2-cyclopentane （ECP） units. The HPD content in the co- polymer products could be easily controlled by changing the feeding amount of HPD under 1 atm of ethylene.
