The molecule is based on an isoxazole ring (a five-membered aromatic heterocycle numbered with the ring oxygen as position 1 and the adjacent nitrogen as position 2).
- The carbon adjacent to the ring oxygen (C5) bears an exocyclic oxygen substituent.
- This oxygen is bonded to a phosphorus atom, which is:
  - doubly bonded to one oxygen,
  - single-bonded to a methyl group, and
  - single-bonded to a negatively charged oxygen.