- A linear chain of four nitrogen atoms, with double bonds between N1 and N2, also N3 and N4.

- At one terminal nitrogen, its original hydrogen is replaced by a phosphorus atom. The N-P connection is a single bond.

- That phosphorus is single-bonded to two negatively charged oxygens and has no other substituents.

- The molecule contains no rings, no carbon atoms, no additional heteroatoms, and no specified stereochemistry.