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

Abstract

A number of classes of polynorbornenes containing cationic iron moieties within their side chains were prepared via ring-opening metathesis polymerization with a ruthenium-based catalyst. The iron-containing polymers displayed excellent solubility in polar organic solvents. The weight-average molecular weights of these polymeric materials were estimated to be in the range of 18,000-48,000. Thermogravimetric analysis of these polymers showed two distinct weight losses. The first weight loss was in the range of 204-260 8C and was due to the loss of the metallic moieties, whereas the second weight loss was observed at 368-512 8C and was due to the degradation of the polymer backbone. Cyclic voltammetry studies of the iron-containing polymers showed that the 18 e À cationic iron centers underwent a reduction to give the neutral 19 e À complexes at half-wave potential (E 1/2 ) ¼ À1.105 V. Photolysis of the metallated polymers led to the isolation of the norbornene polymers in very good yields. Differential scanning calorimetry studies showed a sharp increase in the glass-transition temperatures up to 91 8C when rigid aromatic side chains were incorporated into the norbornene polymers.

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. One property of these complexes was an enhanced solubility in polar organic solvents compared to their organic counterparts.…”

Sandwich Complex‐Containing Macromolecules: Property Tunability Through Versatile Synthesis

“…Ring-opening polymerization is also utilized in the synthesis of macromolecules featuring pendent sandwich complexes. [205][206][207][208] For instance, the living anionic Scheme 35. Radical polymerizations of methyl-substituted cyclobutadiene sandwich complex-containing acrylate.…”

Side‐Chain Metallocene‐Containing Polymers by Living and Controlled Polymerizations

“…82 Shortly after, cationic CIA‐norbornene derivatives containing both one and two CIA groups were prepared and successfully polymerized by ROMP in the presence of Grubbs’ first‐generation catalyst 83. 84 Additionally, the six‐membered ring of the CIA moiety has been further derivatized by methyl or arene groups. The linker between the CIA group and the norbornene has also been modified by various arene units.…”