Introducing Phosphorus into the Overcrowded Thiele’s hydrocarbon Family: Unveiling Contorted Main Group Diradicaloids with Dynamic Redox Behavior

Abstract Thiele's Hydrocarbons (THs) featuring a 9,10‐anthrylene core with switchable geometric and electronic configurations offer exciting possibilities in advanced functional materials. Despite significant advances in main group‐based diradicaloids in contemporary chemistry, main group THs containing an anthrylene cores have remained elusive, primarily due to the lack of straightforward synthetic strategies and the inherent high reactivity of these species. In this study, we utilize an anthracene‐based phosphine synthon to demonstrate, for the first time, a facile and high‐yielding synthetic strategy for robust P‐functionalized overcrowded ethylenes (OCEs) within the TH family. These OCEs feature a non‐symmetric environment, incorporating (thio) xanthyl and phosphaalkene termini. We systematically probe the electronic structures of these derivatives to illustrate the impact of the isolobal phosphaalkene motif on the quinoidal/diradicaloid character. Notably, the compounds exhibit dynamic redox behavior, leading to orthogonally twisted conformational changes upon oxidation, with a kinetically locked redox‐couple.