Abstract

In this talk I will discuss our work on the unexpected and rare luminescence of a square-planar, phenazine-based 3d

Our interdisciplinary approach combines high-level multiconfigurational wave function methods with transient absorption spectroscopy, to provide detailed insights into the excited-state dynamics of the two systems. We uncover a delicate energetic balance between competing relaxation pathways that renders non-radiative, deactivating electronic states inaccessible for the -CH3 complex, yet accessible to its -CF3 analog. We have identified a class of excited states that are crucial to the differing photoactivity of the two species and that (a) are not widely recognized within the photochemistry community, and (b) are not described by conventional TD-DFT approaches, due to their inherently multiconfigurational character. These states arise from the coupling of a metal-centered triplet and a ligand-centered triplet into an overall singlet. The close agreement between computed activation barriers and experimental kinetic data highlights the robustness of our theoretical model.