Patrick O. Shipman

Polynorbornenes Containing Ferrocene Derivatives and Alkyne‐bis(tricarbonylcobalt)

Coordination of dicobalt hexacarbonyl to the alkyne moiety of norbornene complexes containing either ferrocene or η(6) -chlorobenzene-η(5) -cyclopentadienyliron hexafluorophosphate, gave two unique trimetallic complexes available for ROMP. Polymerization of each monomer using Grubbs second generation catalyst gave organoiron/organocobalt polynorbornenes with weight average molecular weights between 55 300 and 69 000 with PDIs between 1.2 and 1.9. Cyclic voltammetric studies of the monomers and polymers at -40 °C showed a reversible reduction for cationic complexes containing η(6) -benzene-η(5) -cyclopentadienyliron and for the dicobalt hexacarbonyl moieties while, a reversible oxidation for the ferrocene containing complex was observed. Thermal analysis showed that the cobalt carbonyl moiety of the polymers degraded near 130 °C; however, the polymeric backbone was stable up to 350 °C. Scanning electron microscopy (SEM) and SEM-EDS indicated that the polymers possessed a fine globular morphology and that the distribution of iron and cobalt atoms was homogenous on the macro-scale.

Design of organoiron macromolecules based on upper rim functionalized calix[4]arenes.

The versatility of cationic cyclopentadienyliron complexes is demonstrated for the generation of calix[4]arene-based dendrimers and polymers. Dendrimers were prepared from a branched organoiron calix[4]arene through subsequent reactions of azo dyes and organoiron complexes. The resulting azo dye-containing metallocalix[4]arenes were soluble in polar organic solvents and displayed λ(max) ranging between 430 and 456 nm. Upon addition of various acids, the λ(max) shifted to higher wavelengths (513-535 nm). In the solid state and in solution, the azo dye-containing metallocalix[4]arenes reversibly changed colour in the presence of acid and base, indicating their potential use as acid sensors. Cyclic voltammetric studies showed that the iron centres of the metallocalix[4]arenes were reversibly reduced at E(1/2)  = -1.49 V. When non-branching organoiron-based calix[4]arene were reacted with dithiols, polymers containing calix[4]arenes either in their side chains or main chains were obtained. The polymers possessed weight average molecular weights between 35 000 and 53 000. The polymers were determined to be thermally stable with backbone decomposition occurring above 500 °C.

Micro and nano-sized polysiloxanes containing organoiron moieties

Utilizing organoiron-mediated nucleophilic aromatic substitution, a number of allylamine-containing organoiron complexes were prepared. Amide formation between 1,1′-ferrocene dicarbonyl chloride and allylamine produced a similar ferrocene compound. These materials were subjected to hydrosilation with methyldiethoxyhydrosilane to generate cationic organoiron siloxanes and ferrocene-containing siloxane complexes. Electrochemical analysis of the allylamine and siloxane complexes showed redox couples characteristic of nitrogen-substituted arene-coordinated cyclopentadienyliron complexes. In situ cleavage of the ethoxy groups followed by the addition of H2SO4 resulted in the formation of polymeric materials. Thermal analysis revealed that the cationic organoiron moieties decomposed between 200 °C and 250 °C, whereas the ferrocene moiety decomposed at 110 °C and the backbones of the polymers began to decompose above 400 °C. The polymers displayed glass transition temperatures between 68 °C and 111 °C. Scanning electron microscopy showed that the polymers possessed very different morphologies, ranging from particulates to crystalline.

Iron-Containing Polymers with Azo Dyes in their Side Chains or Backbones

Interest in organometallic macromolecules has grown exponentially ever since Arimoto and Haven first polymerized vinylferrocene in 1955 [1]. Organometallic polymers are known to possess unique optical, magnetic, and thermal properties which allow for potential applications as chemical sensors, electrocatalysts, modified electrodes, and photo-active molecular devices [2–7]. Organoiron polymers are one of the most prevalent classes of organometallic polymers, with many reports on their synthesis and properties published over the past 50 years [8–11]. Of the many varieties of organoiron species, ferrocene and cationic cyclopentadienyliron complexes are most commonly incorporated into polymers. The cis-trans photoisomerization of azobenzene chromophores is a well-studied phenomena that allows for these materials to be used as electrooptic modulators, photorefactive switches, reversible storage systems, and in nanoscale applications [12–18]. The incorporation of these chromophores into polymers is especially interesting for producing new properties. Manners and coworkers have reported liquid crystalline poly(ferocenylsilanes) containing azo dyes in their side chains [19]. Our group has prepared a number of different organoiron polymers containing azo chromophores in either the main or side chains [20– 23]. This chapter reviews the work that has been performed in this area by our research group.

Feature Article: Macromolecules Containing Pendent Cationic Cyclopentadienyliron Moieties

Abstract This feature article describes the synthesis of various classes of monomers and polymers incorporating organoiron moieties. Polyethers incorporating η6-substituted-arene-η5-cyclopentadienyliron moieties were synthesized via metal-mediated nucleophilic aromatic substitution reactions. Linear polymers incorporating both cationic and neutral organoiron units were prepared; these polymers underwent two electrochemical processes, oxidation of the neutral iron species occurred between 0.89 and 1.0 V and reduction of the cationic iron groups occurred between −1.10 and −1.45 V. Polynorbornenes, polymethacrylates, and polystyrenes were prepared via radical and condensation polymerization of organoiron functionalized monomers. The incorporation of azo dyes into the polymers gave rise to a variety of colored materials that could be photobleached in the presence of hydrogen peroxide. The incorporation of benzothiazole-based dyes resulted in colored polymers with higher λmax values than azobenzene-based dyes....