Na2HgS2 und K2HgS2, zwei Thiomercurate mit isolierten Anionen/Na2HgS2 and K2HgS2, Two Thiomercurates with Discrete Anions

Na HgS and K HgS were obtained as colourless, tabular crystals by reacting the alkali sulfides Na S and K S with red HgS at 970 K. Both compounds are orthorhombic: Na HgS , oP40, s.g. Pbca with a = 18.24(2) Å, b = 7.494(5) Å, c = 7.237(5) Å, Z = 8; K HgS , oP20, s.g. Pbcm a = 10.697(6) Å, b = 7.958(8) Å, c = 7.272(9) Å, Z = 4. Their crystal structures were determined from four circle diffractometer data and refined anisotropically to conventional R-factors of 0.056 (Na HgS ) and 0.062 (K HgS ) for 945 and 485 reflections with F > 3σ(F ), resp. The crystal structures represent new structure types. They are closely related with each other and can be derived from hcp-arrays of the chalcogen-atoms. Characteristic feature is the formation of discrete, almost linear [S - Hs - S] dithiomercurate anions with average HgS-bond lengths of 2.31 Å.