With phenol (26B4M vs. 2B4M) substituted by two tertbutyls at ortho sites, Sm(26B4M)3 has the highest catalytic activity and obtain PCL with highest Mwwhile widest MWD: Sm(26B4M)3> Sm(2B4M)3> Sm(4M)3. 5).

• 两个邻位同时被叔丁基取代的配合物Sm(2684M)3活性最高；所得PCL的Mw和MWD均最大。 5) .