Synthesis, Characterization, and Properties of Symmetrically Substituted, Ring-Opened Poly(ferrocenylalkoxy/aryloxysilanes)

Abstract

A novel and convenient route to the first poly(ferrocenylsilanes) with alkoxy and aryloxy substituents at silicon is reported. The reaction sequence involves (i) unexpectedly facile and clean halogen replacement at the bridging atom of a readily accessible dichlorosilyl-bridged [1]ferrocenophane Fe(η-C5H4)2SiCl2 (3) by OR groups via reactions with aliphatic alcohols and phenols in the presence of an HCl acceptor and (ii) thermal or transition metal-catalyzed ring-opening polymerization of the new [1]ferrocenophanes of structure Fe(η-C5H4)2Si(OR)2 (4). This allows the preparation of high molecular weight poly(ferrocenylsilanes) [Fe(η-C5H4)2Si(OR)2] n with side group substituents such as short chain alkoxy groups (5a − 5b, R = OMe, OEt), fluorinated ethoxy groups (5c, R = OCH2CF3), long chain alkoxy groups (5d − 5 g, R = OBu, OHex, OC12H25, OC18H37), and aryloxy substituents (5h, 5i, and 5k, R = OPh, OPh-p-tBu, OPh-p-tBu, OPh-p-Ph) at silicon. The molecular structures of the [1]ferrocenophane monomers 4a and 4j have been studied by single-crystal X-ray diffraction, and these species possess strained structures with tilt angles between the planes of the cyclopentadienyl ligands of 18−19°. The new poly(ferrocenylsilanes) possess a wide range of glass transition temperatures (T g = −51° (5e) to 97 °C (5k)) and the materials with long chain (OC12 (5f) or OC18 (5g)) alkoxy groups crystallize and exhibit melt transitions (T m) at −30 and +32 °C, respectively. Wide-angle X-ray scattering studies of 5g suggest a lamellar structure with interdigitated side groups. Cyclic voltammetry studies of the selected poly(ferrocenylsilanes) 5a and 5i show the characteristic two-wave pattern for poly(ferrocenes) with interacting iron atoms with a redox coupling ΔE = ca. 0.22 V.

Synthesis and Solution Self‐Assembly of Polyisoprene‐block‐poly(ferrocenylmethylsilane): A Diblock Copolymer with an Atactic but Semicrystalline Core‐Forming Metalloblock

“…[12][13][14] Alternatively, chlorine has been introduced as a substituent through the reaction of Fe(η 5 -C5H4Li)2·TMEDA with SiCl4 or RSiCl3, which, via subsequent nucleophilic substitution reactions at the SiCl2-or SiClRbridge, provides a facile route to [1]ferrocenophanes with alkoxy, aryloxy, and amino substituents at silicon. 15 Hypercoordinate silicon-bridged [1]ferrocenophanes can also be synthesised from chlorosila[1]ferrocenophanes Fe(η 5 -C5H4)2SiRR' (R = R' = Cl or R = Me, R' = Cl) and Li or Fe(η 5 -C5H4)2SiCl(CH2Cl) and N-methyl-N-(trimethylsilyl)acetamide. 16,17 These pentacoordinate species show a pronounced Si-N or Si-O interaction with a pseudo trigonal bipyramidal geometry at the bridging silicon atom in the solid state.…”

“…OC18H37) have been found to undergo side-chain crystallisation. 15 Generally Studies of films and fibres using X-ray diffraction revealed that crystalline PFDMS contains coexisting 2-D mesophases, crystals with a hexagonal or tetragonal packing of macromolecules, and 3-D monoclinic crystalline phases. 93 The formation of partially disordered crystalline phases was attributed to small energy differences between the various polymer conformations.…”

“…7 Alkoxy-substituted PFSs are also generally amorphous, however, the incorporation of long alkoxy chains at silicon, such as n-octadecyloxy, yields PFSs that exhibit side-chain crystallisation to form lamellar structures with interdigitated side groups. 15 The polymer backbone motions of deuterium-labelled PFSs over a range of temperatures were studied by solid-state 2 H NMR spectroscopy, and the nature and rates of molecular motions were determined from the shape of the spectral line and the spin-lattice relaxation time (T1). Symmetrically substituted PFSs with methyl, methoxy, hexyloxy substituents at silicon were studied where the Cp rings were fully deuterated ( Figure 6).…”

Progress in the controllable synthesis of novel ferrocene-based polymers and their applications

“…The preparation of alkyl-, aryl-, alkoxy-, aryloxy-and aminosubstituted polyferrocenylsilanes is possible via the TROP method [14,15].…”

“…Synthesis of the water-soluble poly(ferrocenylsilane) [14]. in water, regardless if the molecular weight was low (2a) or high (2b).…”