Modeling the Direct Activation of Dihydrogen by a P2C2 Cyclic Biradical: Formation of a Cyclic Bis(P-H λ5-phosphorane)

The synthesis of a remarkable cyclic bis(P-H lambda(5)-phosphorane) is reported. A stable phosphorus-heterocyclic biradical, 1,3-diphosphacyclobutane-2,4-diyl, sequentially accepts negatively and positively charged hydrogen atoms to afford 2,4-diphospha-1,3-cyclobutadiene with a diylidic structure containing two P-H bonds.