Mg(NH<sub>3</sub>)<sub>6</sub>Hg<sub>22</sub>, a Mercury Intercalation Compound

Very pure Mg dissolves in liquid NH<sub>3</sub> with a blue color. Attempts to isolate solid Mg(NH<sub>3</sub>)<i><sub>x</sub></i> were not met with success. MgHg alloy reacts with liquid NH<sub>3</sub> with formation of Mg(NH<sub>3</sub>)<sub>6</sub>Hg<sub>22</sub>, as established by a single-crystal structure determination. The octahedral Mg(NH<sub>3</sub>)<sub>6</sub> units have Mg−N distances typical for Mg(NH<sub>3</sub>)<sub>6</sub><sup>2+</sup>. They are embedded in layers into cavities of the mercury metal matrix, resulting in a layered structure. <i>T</i><sub>c</sub> of this superconducting material is 3.6 K, which is lower than that of pure Hg (4.19 K).