With Extra Care, A New Mercury Azide Is Made And Analyzed

Mercury-containing substances have fascinated scientists since the days of alchemy. Millon’s base, [Hg₂N]OH•2H₂O, and calomel, Hg₂Cl₂, are classic examples. But mercury-laden substances are toxic, and when paired only with nitrogen, they are explosive, making them difficult to study. Overcoming those challenges, researchers in Germany have plugged a mercury knowledge gap by synthesizing and characterizing [Hg₂N]N₃, the highly explosive azide salt of Millon’s base (Angew. Chem. Int. Ed. 2013, DOI: 10.1002/anie.201305545). To start, Axel Schulz and Alexander Villinger of the University of Rostock and coworkers synthesized the mercury azide Hg(N₃)₂ and combined it with ammonia in water. The reaction produced [Hg₂N]N₃, a yellowish compound that crystallizes in cubic and hexagonal forms. The researchers used different reactions to produce pure samples of each form. But given [Hg₂N]N₃’s explosiveness, the researchers could use only certain methods to analyze the samples. With extra care and safety gear, they successfully studied the samples with X-ray powder diffraction as well as with infrared, Raman, and optical emission spectroscopy. The researchers say [Hg₂N]N₃ is the first nitrido-metal azide with a three-dimensional network structure to be characterized, allowing for comparisons with other mercury azides.