Olav Marcus Aagaard

New synthetic routes to poly (isothianaphthene) I. Reaction of phthalic anhydride and phthalide with phosphorus pentasulfide

Abstract A new route for the formation of the low bandgap polymer poly(isothianaphthene) is presented. The route comprises the reaction of phthalic anhydride or phthalide with phosphorus pentasulfide at elevated temperatures ( T ⩾ 120 °C), and leads to the formation of poly(isothianaphthene) in one single step. The product obtained was analysed by elemental analysis, IR, Raman and solid state NMR spectroscopy. Chemical doping and dedoping of the material were investigated, and the maximum conductivity obtained was 10 S cm −1 by doping with NOSbF 6 . Both doped and undoped samples of poly(isothianaphthene) prepared by this new route were thermally very stable in air or in an inert helium atmosphere as shown by thermogravimetric analysis. Furthermore, the conductivity of a doped sample remained unchanged up to 250 °C in air. Preliminary results showed that the reaction with phosphorus pentasulfide can also be used to obtain nitrogen analogues of poly(isothianaphthene).

First principles molecular dynamics applied to homogeneous catalysis: on ethylene insertion mechanisms and metathesis

Abstract We have summarized part of our work involving first principles molecular dynamics simulations on organometallic-based homogeneous catalysts. Explicit dynamics effects can be uniquely extracted from such simulations, and related to structure and reactivity. Examples given deal with metallocene-based ethylene polymerisation, ethylene insertion in a platinum hydride, and olefin metathesis. The dynamics simulations in particular reveal information on the flexibility of these molecular systems, and elucidate mechanistic details (e.g., relevance agostic interaction). For the Ru-based metathesis catalyst an alternative simulation approach has been applied, which has enabled us to make detailed comparison between simulation results and the reaction mechanism proposed by Dias et al. [E.L. Dias, S.T. Nguyen, R.H. Grubbs, J. Am. Chem. Soc. 119 (1997) 3887], showing that the results of our simulations reveal and lend support to the mechanism proposed by Grubbs. These include, in the order of appearance in the reaction scheme, the relative easiness of Cl–Ru–Cl cis–trans configurational exchange, carbene rotation and the loss of one phosphine, formation of a metallacyclobutane intermediate, and finally completion of the metathesis reaction. The presence of a small fraction of the monophosphine complex is confirmed by the present simulations. Starting from the observation that selective bond excitation is necessary to exhibit reactivity, the higher activity of the monophosphine system compared to bisphosphine complexes reported by Dias et al. can be understood.

New synthetic routes to poly(isothianaphthene). II. Mechanistic aspects of the reactions of phthalic anhydride and phthalide with phosphorus pentasulfide

The results of some mechanistic studies on the formation of poly(isothianaphthene) from phthalic anhydride and phthalide by reaction with phosphorus pentasulfide (P4S10) are described. Based on the observed intermediates during the polymerization and their reactivity, it is proposed that both reactions occur by a sequence of substitution (thionation), isomerization, and polymerization reactions. P4S10 is the most efficient reagent for the conversion of phthalic anhydride and phthalide, and Lawessons Reagent (a commonly used thionating reagent) gives less satisfactory results. It is suggested that P4S10 assists the rate-determining step. Oxygen-containing monomers do not polymerize in the absence of a thionating reagent under the conditions for the synthesis of PITN, thereby keeping the incorporation of oxygen into the polymeric backbone to a minimum.

Precursor monomer route: A novel concept for producing highly conductive polypyrrole films

Abstract Heating of micro porous UHMW-PE films, impregnated with a solution of pyrrole-2-carboxylic acid and FeCl 3 , results in tough and flexible films with conductivities up to 10 S/cm. Within the films a continuous network of polypyrrole is present as a coating layer on the micro fibrils of polyethylene. By triggering of the reaction via thermochemical, oxidative decarboxylation of the pyrrole-2-carboxylic precursors, a controlled and efficient polymerisation is provided, resulting in a fast and continuous production process.

New synthetic routes to poly(isothianaphthene): III. Polymerization of dithiophthalide and 1,1,3,3-tetrachlorothiophthalan

Abstract In this paper, the polymerization of sulfur-containing precursor molecules to poly(isothianaphthene) (PITN) is described. Most attention has been devoted to the polymerization of dithiophthalide, as other useful precursors were synthetically less accessible. The thermal polymerization of dithiophthalide leads to the formation of undoped PITN, which had a conductivity in the order of 10 −4 S cm −1 . The insoluble polymer was characterized by IR, Raman and solid state NMR spectroscopy, and elemental analysis. The polymerization proceeds by simply heating the precursor without the presence of any added reagent or solvent and is the first non-oxidative route to PITN.