Mechanistic investigations of the addition polymerization of phosphaalkenes

• Applicant: Dr. Klaus Dück
• Subject Area: Inorganic Molecular Chemistry - Synthesis and Characterisation
• Term: from 2015 to 2017
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 284364346

The interest in polyphosphaalkenes, macromolecules containing P-C bonds, is based on their structural similarity to polyolefines. Despite these similarities the inclusion of a phosphorus atom enables a wide range of functionalities currently not available in the organic polymers. Although the addition polymerization of phosphaalkenes is seemingly a straightforward reaction, recent mechanistic investigations show that the main pathway proceeds through C-H activation at the substituents of the phosphorus atom. Nevertheless, normal polymerization of the P=C moiety cannot be completely excluded. These competing routes lead to microstructures comprised of two different polymeric units in random distributions. This project intends to find a way of directing the reaction pathway to one route, by modelling the phosphaalkene precursors. First, the conventional substituents at the phosphorus atom will be replaced by bulky or non-hydrogen containing units to avoid the C-H activation. Furthermore, the expected intermediates will be stabilized by metal-containing substituents at the carbon atom, allowing investigation of the influence of metals on the radical or anionic intermediates. Not only will this work be an important contribution to the understanding of the polymerization mechanisms of phosphaalkenes, the project will also result in the isolation of completely new phosphorus and metal-containing polymers. Depending on the results of the mechanistic studies, the findings will be applied to the polymerization of phosphabutadienes. This phosphorus containing analog of butadiene, a common precursor for rubberlike materials, has not been investigated with regard to its polymerization behavior to date. During the project, a synthetic route for a precursor with an hydrogen containing carbon backbone will be developed and its addition-polymerization subsequently investigated. The resulting new class of polymers will possess additional functional groups and unknown properties, making them the subject of wide-ranging interests in inorganic chemistry and material science.

• DFG Programme: Research Fellowships
• International Connection: Canada
• Host: Professor Dr. Derek Gates