Platinum-or Palladium-Catalyzed Ring-Opening Homo- and Co-polymerization of Silicon- and Germanium-Bridged [1]Ferrocenophanes

N. P. Reddy, H. Yamashita, and Masato Tanaka
[J. Chem. Soc., Chem. Commun., p. 2263, 1995]

[1]Silaferrocenophane (1) and [1]germaferrocenophane (3) undergo ring-opening polymerization (ROP) in the presence of a catalytic amount of phosphine-free platinum or palladium complexes at room temperature (eq 1) to give the corresponding polymers 2 or 4 in high yields. The nature of the catalyst remarkably influences the molecular weight of the polymers (Table 1). Among the tested catalysts, Pt(cod)₂ (cod = cycloocta-1,5-diene) gives the highest molecular weight polymers, whereas, Pt₂(dba)₃ and Pd(dba)₂ (dba = dibenzylideneaceton) produce low molecular weight polymers. In the presence of Pd(cod)Cl₂, both 1 and 3 undergo a rapid ROP to give insoluble polymers.
This process can be applied for the copolymerization of 1 and 3. In the presence of Pt₂(dba)₃, 1 and 3 underwent copolymerization to give a random copolymer consisting 1, 1'-ferrocenylene, silylene, and germylene units.