Study of the Air‐Tolerant 1,3‐Diphosphacyclobutane‐2,4‐diyl through the Direct Arylation

Installing π‐functional substituents on the skeletal phosphorus atoms of the air‐tolerant 1,3‐diphosphacyclobutane‐2,4‐diyl unit are promising for tuning the open‐shell singlet P‐heterocyclic chromophore. The sterically encumbered 1,3‐diphosphaCycloButen‐4‐yl Anion (CBA), generated from the phosphorus‐carbon triple bond, was available for the regioselective arylation via nucleophilic aromatic substitution (SNAr) reaction, addition to arynes, and single‐electron transfer (SET) process affording the corresponding P‐arylated 1,3‐diphosphacyclobutane‐2,4‐diyls. The photo‐absorption and redox properties correlated with the effects of the aryl substituents on the 1,3‐diphosphacyclobutane‐2,4‐diyl unit. The X‐ray analyses enabled not only to discuss the metric parameters but also to visualize the radicalic electrons via the electron‐density distribution analysis. The electron‐donating character of the P‐heterocyclic chromophores induced the p‐type semiconductor behavior. Detection of hydrogen fluoride via formation of the 1λ5,3λ5‐diphosphete derivative was also developed. The sterically encumbered 1,3‐diphosphaCycloButen‐4‐yl Anion (CBA) was regioselectively arylated via SNAr reaction, addition to arynes, and SET process. The obtained air‐stable 1,3‐diphosphacyclobutane‐2,4‐diyls indicated the aryl effects for the band tuning, semiconductor behavior, and detection of hydrogen fluoride. Intensive structural analyses including visualization of the radicalic electrons were performed.