[{"from": "human", "value": "Synthesize a molecule that matches the given characteristics. The molecule appears as a whitish to gray-colored crystalline solid. Denser than water. Contact may irritate skin, eyes and mucous membranes. Vapors may be toxic by inhalation. Used to make other chemicals."}, {"from": "gpt", "value": "[NH2-1].[NH2-1].[Mg+2]"}]