An Isolable Phosphinidene Oxide

Abstract Phosphorus monoxide (PO•) was the first compound with a P–O bond to be spectroscopically detected in interstellar space. On Earth, PO•, and related functionalized molecules such as R–P = O (R = OH, CH₃, OCH₃, Ph), have been studied in inert gas matrices at ultralow temperatures (3–15 K). These species are believed to be key intermediates in the degradation/combustion of organic phosphorus compounds (a class of chemicals that includes chemical warfare agents and flame retardants). However, despite numerous attempts, an isolable example of R–P = O has eluded synthetic chemists to date. Here we describe the use of an extremely bulky amine ligand to isolate the first two-coordinate phosphorus(III) oxide. Reactivity studies on this and other related compounds shows that phosphorus center can be readily oxidized, and that in doing so, the P–O bond remains intact, an observation that is of interest to the proposed reactivity of phosphorus monoxide (PO•).