Abstract The synthesis, structures, and ring-opening polymerization (ROP) activity of new dimethyl-ansa-and-non-ansa-zirconocene complexes are reported. The substituted indene precursors 1-C 9 H 7 R [R= CH 3 (1), CH 2 Ph (2) and C 2 H 4 (C 4 H 7 O 2)(3)] were synthesised by treating RBr [R= CH 2 Ph and C 2 H 4 (C 4 H 7 O 2)] or MeI with indenyllithium. Likewise, bridged indenyl/cyclopentadiene compounds [Me 2 Si (3-C 9 H 6 ...