Activation of Small Molecules by Phosphorus Biradicaloids

The reactivity of biradicaloid [P(-NTer)](2) was employed to activate small molecules bearing single, double, and triple bonds. Addition of chalcogens (O-2, S-8, Se-x and Te-x) led to the formation of dichalcogen-bridged P2N2 heterocycles, except from the reaction with molecular oxygen, which gave a P2N2 ring featuring a dicoordinated P-III and a four-coordinated P-V center. In formal [2e+2e] addition reactions, small unsaturated compounds such as ethylene, acetylene, acetone, acetonitrile, tolane, diphenylcarbodiimide, and bis(trimethylsilyl)sulfurdiimide are readily added to the P2N2 heterocycle of the biradicaloid [P(-NTer)](2), yielding novel heteroatom cage compounds. The synthesis, reactivity, and bonding of the biradicaloid [P(-NTer)](2) were studied in detail as well as the synthesis, properties, and structural features of all addition products.