Frustrated Lewis Pairs based on Polymethylenephosphines

• Applicant: Dr. Kurt F. Hoffmann
• Subject Area: Inorganic Molecular Chemistry - Synthesis and Characterisation
• Term: since 2024
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 539438668

In recent years, the concept of frustrated Lewis pairs (FLPs) has been thoroughly investigated and it finds versatile applications, for example in catalytic metal-free hydrogenation reactions or for small molecule activation. However, there are still some challenges, such as the sensitivity of such compounds towards moisture and air, which makes it difficult to handle such systems so far. Switching from monomeric compounds to polymeric variants of these FLPs could remedy this and achieve increased stability and reusability. The aim of this research project is therefore to develop novel polymeric FLPs based on Lewis-basic polymethylene phosphines (PMPs) and to investigate their potential in terms of small molecule activation reactions and catalytic properties. These PMPs are inorganic polymers in which Lewis-basic phosphorus centers are incorporated in the backbone of the polymer. Since a large number of possible substitution patterns of the PMPs are conceivable and these have an influence on their reactivity, monomeric model compounds that mimic the chemical environment of the polymeric phosphines are initially considered. This allows a straightforward selection of promising PMP derivatives for the subsequent synthesis of the polymeric Lewis bases. After successful synthesis of the different PMPs, these will now be investigated for potential FLP reactivity in combination with different Lewis acids and different substrates. In doing so, new properties and reactivity differences (e.g. hydrolysis stability) compared to their monomeric analogues will be investigated. Other advantages that polymeric FLPs could offer are a possible reusability by using block copolymers or achieving a different selectivity in subsequent reactions due to cooperative effects. To investigate the potential of polymeric FLPs, fluorinated hydrocarbons will be investigated in addition to typical substrates such as molecular hydrogen or carbon dioxide to perform C-F activation reactions with the obtained compounds. The combination of FLP chemistry with polymeric structures is still a largely unexplored field, which, however, might be able to overcome major shortcomings of monomeric FLPs. Besides an improved stability, selectivity and catalytic performance, the discovery of entirely new polymer-specific properties is envisioned.

• DFG Programme: WBP Fellowship
• International Connection: Canada
• Host: Professor Dr. Derek Gates