Single electron transfer processes in frustrated Lewis pairs

Over the years, frustrated Lewis pairs (FLPs), such as the archetypal intermolecular FLP PMes3– B(C6F5)3 have been employed for the heterolytic activation of a wide range of small molecules, including dihydrogen and carbon dioxide. However, the activation of methane, for example, remains a major challenge. The discovery of radical formation in FLP systems offers significant potential in this regard, as it enables access to new, more reactive donor–acceptor systems. Previously, our group identified two distinct types of single-electron transfer (SET) processes in FLP chemistry, namely thermal SET and photochemical SET upon irradiation of a charge-transfer (CT) band, both yielding radical (ion) pairs. This thesis addresses both processes in intermolecular FLPs with the aim of strengthening the understanding of thermal and photochemical SET.
Firstly, the methods used to make a distinction between thermal and photochemical SET are discussed, before giving an overview of the current state. Subsequently, the efforts towards stable radical ion pairs using quinones as electron acceptors is discussed, using both phosphine and amine electron donors. Next, the formation of the charge transfer band is investigated using various pnictogen based electron donors and efforts are described in the design and synthesis of a new cationic borane. Lastly, a kinetic study into the formation of the encounter complex of FLPs has been described.