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1 Results Search for catalysts which can control the regio- and stereoselectivity for olefin polymerization is a very important research subject.For the polymerization of isoprene,we have recently achieved,for the first time,the isospecific 3,4 polymerization by using a cationic rare earth metal alkyl catalyst bearing a silylene-linked cyclopentadieny-phosphido ligand[1], and the cis-1,4 living polymerization by a bis(phosphinophenyl)amido-ligated rare earth metal catalyst[2]. In addition to these ligand-modification approaches,we wish to report here that an alkyl aluminum compound can be used to switch the regio- and stereoselectivity in the polymerization of isoprene catalyzed by an amidinate-ligated yttrium catalyst (Scheme 1).The isolation and structural characterization of the amidinate-ligated yttrium complex and the Y/Al heterotrimetallic complexes and their relation to the polymerization mechanism will also be described.
1 Results Search for catalysts which can control the regio- and stereoselectivity for olefin polymerization is a very important research subject. For the polymerization of isoprene, we have recently achieved, for the first time, the isospecific 3,4 polymerization by using a cationic rare earth metal alkyl catalyst bearing a silylene-linked cyclopentadieny-phosphido ligand [1], and the cis-1,4 living polymerization by a bis (phosphinophenyl) amido-ligated rare earth metal catalyst [2]. approaches, we wish to report here that an alkyl aluminum compound can be used to switch the regio- and stereoselectivity in the polymerization of isoprene catalyzed by an amidinate-ligated yttrium catalyst (Scheme 1). The isolation and structural characterization of the amidinate-ligated yttrium complex and the Y / Al heterotrimetallic complexes and their relation to the polymerization mechanism will also be described.