[{"from": "human", "value": "Use the given information to create a molecule that fulfills the desired purpose. The molecule is a phosphorus oxoacid and an acyclic phosphorus acid anhydride. It is a conjugate acid of a diphosphonate(1-)."}, {"from": "gpt", "value": "[O][P+1][=Branch1][C][=O][O][P+1][=Branch1][C][=O][O]"}]