page_title: Frustrated Lewis pair
section_title: Carbon capture
hierarchical_section_title: Frustrated Lewis pair / Carbon capture
caption_attribution_description: English: Carbon dioxide capture by Frustrated Lewis pair drawn in chemdraw
context_page_description: In chemistry, a frustrated Lewis pair is a compound or mixture containing a Lewis acid and a Lewis base that, because of steric hindrance, cannot combine to form a classical adduct. Many kinds of FLPs have been devised, and many simple substrates exhibit activation.
  The discovery that some FLPs split H₂ triggered a rapid growth of research into FLPs. Because of their "unquenched" reactivity, such systems are reactive toward substrates that can undergo heterolysis. For example, many FLPs split hydrogen molecules.
  Thus, a mixture of tricyclohexylphosphine and trisborane reacts with hydrogen to give the respective phosphonium and borate ions:
  This reactivity has been exploited to produce FLPs which catalyse hydrogenation reactions.
context_section_description: FLP chemistry is conceptually relevant to carbon capture. Both an intermolecular (Scheme 1) and intramolecular (Scheme 2) FLP consisting of a phosphine and a borane were used to selectively capture and release carbon dioxide. When a solution of the FLP was covered by an atmosphere of CO₂ at room temperature, the FLP-CO₂ compound immediately precipitated as a white solid.
  Heating the intermolecular FLP-CO₂ compound in bromobenzene at 80 °C under vacuum for 5 hours caused the release of around half of the CO₂ and regenerating the two constituent components of the FLP. After several more hours of sitting at room temperature under vacuum, total release of CO₂ and FLP regeneration had occurred.
  The intramolecular FLP-CO₂ compound by contrast was stable as a solid at room temperature but fully decomposed at temperatures above -20 °C as a solution in dichloromethane releasing CO₂ and regenerating the FLP molecule.
  This method of FLP carbon capture can be adapted to work in flow chemistry systems.
caption: Scheme 2: Intramolecular FLP CO2 capture and release.
exif: {}