Living ROMP Synthesis and Redox Properties of Diblock Ferrocene/Cobalticenium Copolymers

Abstract

Using the third-generation Grubbs catalyst, the living ring-opening metathesis polymerization of ferrocene/cobalticenium copolymers is conducted with theoretical numbers of 25 monomer units for each block, and their redox and electrochemical properties allow using the Bard-Anson electrochemical method to determine the number of metallocenyl units in each block.

Living ROMP Synthesis and Redox Properties of Triblock Metallocopolymers Containing Side‐Chain Iron and Cobalt Sandwich Complexes

“…Two norbornene amino derivatives, N ‐[11‐amine‐3′,6′,9′‐trioxahendecyl]‐ cis ‐5‐norbornene‐ exo ‐2,3‐dicarboximide ( 15 ) and N ‐(2‐aminoethyl)‐ cis ‐5‐norbornene‐ exo ‐2,3‐dicarboximide ( 16 ) were used for the syntheses of the functional organometallic monomers 2 , 3 , 4, and 5 according to the published procedures . The monoamine 15 served as a precursor for the syntheses of the norbornene derivatives of the monomers containing either Fc or Fc* group, respectively, 2 and 3 , whereas the monoamine 16 was used for the synthesis of the monomers bearing either the mixed iron‐sandwich complex (FbX) or cobalticenium hexafluorophosphate (CcX), respectively, 4 and 5 . These amidation reactions were conducted upon reaction with the known chlorocarbonyl iron or cobalt sandwich derivatives (Scheme S1, Supporting Information).…”

“…These amidation reactions were conducted upon reaction with the known chlorocarbonyl iron or cobalt sandwich derivatives (Scheme S1, Supporting Information). Based on previous reports, the ROMP reactions of these monomers were proven to be “controlled” and “living,” which gives the opportunity to fabricate triblock copolymers containing one neural Fc (or Fc*) group and two cationic FbX and CcX redox moieties. However, to successfully carry out these syntheses, the ROMP characteristics of the intermediate homopolymers and diblock copolymers should be taken into account .…”

“…In this respect, key differences were found among these routes. For example, CH 2 Cl 2 is a perfect solvent for the ROMP of neutral monomers 2 and 3 , whereas DMF is the only choice for polymerization of the cationic monomers 4 and 5 . At the feed molar ratio [monomer]:[catalyst 1 ] of 25:1, it takes 15 min to finish the ROMP of Fc monomer 2 , whereas ROMP of the Fc* monomer 3 is completed in 10 min, with nearly 100% conversion .…”

“…At the feed molar ratio [monomer]:[catalyst 1 ] of 25:1, it takes 15 min to finish the ROMP of Fc monomer 2 , whereas ROMP of the Fc* monomer 3 is completed in 10 min, with nearly 100% conversion . The slowest rate was observed for the ROMP of monomers 4 and 5 in DMF, in which 30 min (at least) is required to achieve 100% conversion . For the synthesis of diblock copolymers containing cationic FbX and CcX groups, 30 min is needed to achieve the ROMP of monomer 5 providing the known ruthenium (Ru)‐ended homopolymers.…”

“…Cis ‐5‐norbornene‐ exo ‐2,3‐dicarboxylic anhydride (95%), tetraethylene glycol, ethanediamine, ethyl vinyl ether (EVE, 99%), and Grubbs 2nd generation catalyst were purchased from Aldrich and used directly. Grubbs 3rd generation catalyst 1 , Fc‐containing monomer 2 , Fc*‐containing monomer 3 , the cationic FbX‐containing monomer 4 , and the cationic CcX‐containing monomer 5 were synthesized following the procedures reported in the literature. All the other chemicals were from commercial sources and used as received.…”