Controlled molecular design of ether- and ester-bridged norbornenes and their ring-opening metathesis polymerizations

Abstract

A series of functionalized polynorbornenes containing pendent ether- or ester-bridged poly(aromatic ether) chains were prepared. The ether-bridged norbornene complex was synthesized via cyclopentadienyliron-mediated nucleophilic aromatic substitution reactions. This methodology, combined with that of dicyclohexylcarbodiimide-mediated coupling, allowed for the formation of novel oligomeric aryl ether and ester substituted norbornene complexes. Photolytic demetallation gave the monomers in good yields. Structural identification of the exo and endo isomers of both the metallated and demetallated norbornene derivatives was accomplished using HH and CH COSY NMR techniques. Ring-opening metathesis polymerization (ROMP) of these monomers using RuCl3(hydrate) and (Cy3P)2Cl2Ru=CHPh allowed for the preparation of the functionalized polynorbornenes. Thermal analysis of the resulting polymeric materials demonstrated greater thermal stability as the number of aryl ether groups increased.Key words: aromatic ethers, cyclopentadienyliron, polynorbornene, ROMP, ruthenium catalysts.

Star-Shaped Polyaromatic Ethers Coordinated to Redox-Active Cyclopentadienyliron Moieties

“…Complex 7 was subsequently reacted with the chloroarene complexes 8-10, whose syntheses have previously been reported. [18] The resulting star polymers (11-13) contained 9, 12 and 15 metallic moieties pendent to their backbones, respectively. It was found that the solubility of the polymers decreased with increasing molecular weight, however all polymers could be solubilized in polar aprotic solvents such as DMF and dimethyl sulfoxide (DMSO).…”

Polynorbornenes Containing Ferrocene Derivatives and Alkyne‐bis(tricarbonylcobalt)

“…The ring opening metathesis polymerization (ROMP) of functionalized norbornene using Grubbs catalysts is a well documented process that is tolerant of a variety of functional groups 8–14. Our group has previously used Grubbs first generation catalyst to polymerize polynorbonenes with η 6 ‐arene‐η 5 ‐cyclopentadienyliron complexes in the side chain 15–18.…”

Synthesis of norbornenes containing cationic mono‐ and di(cyclopentadienyliron)arene complexes and their ring‐opening metathesis polymerization

“…Our research has focused on the synthesis of monomeric and polymeric materials containing arenes coordinated to cationic cyclopentadienyliron moieties in their backbones or side chains 21, 24–26, 30–35. Recently, we synthesized thermally stable polynorbornene with pendant ether linkages 36–38. This article describes the synthetic strategies and structural characterization of a series of organoiron monomeric and polymeric materials.…”