[{"from": "human", "value": "Generate a molecule based on the given description. The molecule is a mixed valence oxide of cobalt. It is a black antiferromagnetic solid. Cobalt is a metallic element with the atomic number 27. It is found naturally in rocks, soil, water, plants, and animals. In small amounts cobalt is an essential element for life, as it is part of vitamin B12. However, excess exposure is known to exhibit toxic effects. (L29, L30)"}, {"from": "gpt", "value": "[O-2].[O-2].[O-2].[O-2].[Co+2].[Co+3].[Co+3]"}]