Light-Induced Small Molecule Fixation by Diradicals

点击翻译按钮获取中文摘要

The chemical storage of energy constitutes a grand challenge and implies the transformation of strong bonds, as in N2, CO2, etc., to weaker bonds. Ideally and in accordance with the blueprints of photochemical approaches, the sun’s energy is directly used to cleave these bonds (“photoactivation”) in a sequential manner. Common feature of most approaches in this field are transition metals due to the requirement to control “partitioning” of energy into smaller “energy packages”. However, recent years brought much progress in the field of low-valent main-group compounds with transition metal-like reactivity and electronic structures such as small frontier orbital energy gaps. Investigations are driven by the incentives to substitute rare and toxic metals with earth-abundant and environmentally benign elements. Molecules with exceedingly small HOMO–LUMO energy gaps or even a triplet ground state such as dioxygen are referred to as diradical(oid)s. Tremendous progress has been made in their isolation. Yet, the bond activation chemistry of diradicals has rarely been explored. Despite the analogy of their electronic structure with transition metals and dioxygen, their photoinduced reactivity, beyond transient diradical states and acenes, remains even unchartered territory. Within this project, we will demonstrate that diradicaloid, “metallomimetic” compounds based only on earth-abundant elements may photochemically activate small molecules such as dinitrogen, and convert them into value-added products.