[{"from": "human", "value": "Synthesize a molecule that matches the given characteristics. The molecule is an organophosphonate oxoanion obtained by deprotonation of the phosphonate OH groups of methylphosphonic acid. It is a conjugate base of a methylphosphonate(1-)."}, {"from": "gpt", "value": "[C][P][=Branch1][C][=O][Branch1][C][O-1][O-1]"}]