Photochemical Single Electron Transfer Activation of Alkyl- and Aryl-halides by a Cerium(III) Triamidoamine Complex

Procedures for activating and degrading compounds containing carbon-halogen bonds are highly sought after due to the environmental persistence and potential hazards of such compounds. Such activations are challenging because of the high stability of these bonds, particularly those with C-F bonds. Here, we report on the activation of carbon-halogen bonds, including C-F bonds, by the cerium(III)-triamidoamine complex CeIIITRENTIPS (1, TRENTIPS = tris-(2-(tri-iso-propylsilylamidoethyl)amine). Under light irradiation, 1 reaches a strongly negative excited state redox potential, and our measurements enable it to be estimated as 3.2 V relative to Cp2Fe0/+. Hence, the photo-reactivity of 1 with carbon-halogen bonds has been established with numerous examples, including Persistent Organic Pollutants (POPs) and fluorinated compounds. The photoactivation of POPs is rapid, but the photoactive nature of the cerium(IV) products precludes complete conversion. This study provides insight into the activation of POPs that may benefit the future design of photodegradation approaches for these highly problematic compounds.