[{"from": "human", "value": "Provide a description of this molecule. [O][=Os][=Branch1][C][=O][=Branch1][C][=O][=O]"}, {"from": "gpt", "value": "The molecule is an osmium coordination entity consisting of four oxygen atoms bound to a central osmium atom via covalent double bonds. It has a role as an oxidising agent, a poison, a fixative and a histological dye."}]