[{"from": "human", "value": "Design a molecule that meets the criteria outlined in the description. The molecule is a nitrogen mustard."}, {"from": "gpt", "value": "[C][Branch2][Ring1][Ring1][C][O][P][=Branch1][C][=O][Branch1][C][N][N][Branch1][Ring2][C][C][Cl][C][C][Cl][C][=Branch1][C][=O][O]"}]