Hyperbranched Poly(ferrocenylphenylenes):  Synthesis, Characterization, Redox Activity, Metal Complexation, Pyrolytic Ceramization, and Soft Ferromagnetism

Hyperbranched poly(ferrocenylphenylenes) (hb-PFPs) with high molecular weights were synthesized by the copolycyclotrimerizations of (E,E)-1,1‘-bis[2-(4-ethynylphenyl)vinyl]ferrocene (1) with (E)-1-[2-(4-ethynylphenyl)vinyl]ferrocene (2) catalyzed by TaCl5−Ph4Sn at room temperature in high yields (up to 97%). Effects of reaction conditions, such as monomer and catalyst concentrations, reaction time and molar feed ratio (r1/2), on the copolycyclotrimerization were investigated. Solubility of the copolymer is decreased with an increase in its content of diyne component (N1/N2). The hb-PFPs were characterized by IR, NMR, UV, CV and TGA analyses. The copolymers are redox active, whose oxidation potentials are decreased with an increase in N1/N2. They are thermally stable, losing ∼5% of weights when heated to 384−400 °C and retaining ∼70% of weights when pyrolyzed at 1200 °C. The complexation with cobalt carbonyl further metallizes the hb-PFPs and the pyrolytic ceramization of the cobalt−polymer complexes yields soft ferromagnetic ceramics with high magnetizability (Ms up to ∼126 emu/g) and low coercivity (Hc down to ∼0.068 kOe).