Synthesis and Structure of the First Sulfur-Bridged [1]Ferrocenophane

摘要

[l]Ferrocenophanes have attracted attention because of their interesting structures and reactivity, their applications as surface deiivatization agents, and very recently as precursors to novel transition-metal-based polymers through ling-opening polymerization (ROP). The first [1]fenocenophane, 1 (ER_X = SiPh_2), was isolated by Osborne et al. in 1975 from the reaction of dilithioferrocene tmeda (tmeda = tetramethylethyl-enediamine) and Ph_2SiCl_2 . This species was shown to possess an unusual, strained structure in which the planes of the cy-ciopentadienyi ligands were tilted with respect to one another by about 19 deg. Germanium-bridged [l]fenocenophanes 1 (E = Ge) have been subsequently reported and possess slightly less strained structures. Group 15 elements such as phosphorus and arsenic have also been successfully incorporated into the bridge structure, and the cyclopentadienyl ring-tilts for species 1 (E = P or As) are greater (about 2.3-27°). In 1992 we reported the discovery that silicon-bridged [1]ferrocenophanes undergo facile thermally induced ROP reactions to afford high molecular weight (M_0>10~5) poly(fetro-cenylsilanes) 2 (E = Si, R_x = Me_2, Ph_2) (Scheme 1). We have also observed that related [1]ferrocenophanes with germanium or phosphorus in the bridge polymerize thermally and that ROP can be induced in solution by using anionic initiators.