Bildung von NH4[Hg3(NH)2](NO3)3 und Umwandlung in [Hg2N](NO3)

Formation of NH₄Hg₃(NH)₂](NO₃)₃ and Transformation to Hg₂N](NO₃) NH₄Hg₃(NH)₂](NO₃)₃ ( 1 ) and Hg₂N](NO₃) ( 2 ) are obtained from conc. aqueous ammonia solutions of Hg(NO₃)₂ at ambient temperature and under hydrothermal conditions at 180 °C, respectively, as colourless and dark yellow to light brown single crystals. The crystal structures {NH₄Hg₃(NH)₂](NO₃)₃: cubic, P4₁32, a = 1030.4(2) pm, Z = 4, R_all = 0.028; Hg₂N](NO₃): tetra gonal, P4₃2₁2, a = 1540.4(1), c = 909.8(1) pm, Z = 4, R_all = 0.054} have been determined from single crystal data. Both exhibit network type structures in which HNHg₃] and NHg₄] tetrahedra of the partial structures of 1 and 2 are connected via three and four vertices, respectively. 1 transforms at about 270 °C in a straightforward reaction to 2 whereby the decomposition products of NH₄NO₃ are set free. 2 decomposes at about 380 °C forming yellow HgO. Most certainly, 1 is identical with a mineral previously analyzed as “Hg(NH₂)(NO₃)” with the same Hg:N:O ratio.