Synthesis and Ring-Opening Polymerization of a Tin-Bridged [1]Ferrocenophane

摘要

[1]Ferrocenophanes 1 possess a single-atom bridge ER_x linking the two cyclopentadienyl ligands. The idea that species such as 1 (E = Si) might exist was, (understandably) dismissed by Rosenberg and Neuse in 1970 who stated that such structures wouldbe "impossibly strained." Since the synthesis of the first [1]ferrocenophane 1, ER_x = SiPh_2, in 1975 by the reaction of dilithioferrocene-tmeda (tmeda = tetramethylethylene-diamine) with Ph_2SiCl_2, a range of analogous species with Group 14 (Si, Ge),Group 15 (P, As). Group 16 (S), and Group 4 (Ti, Zr, Hf) bridging elements have subsequently been prepared. These molecules possess interesting strained structures with tilt angles between the planes of the cyclopentadienyl ligands between 6° (for 1 (E=Zr)) and 31 (for 1 (ER, = S)). Recently [1]ferrocenophanes have attracted attention as precursors to novel high molecular weight poly-(metallocene)s 2 by ring-opening polymerization (ROP).