Die Kristallstrukturell von CaHg(SCN)4 · nH2O (n = 2,3). Verwandtschaftsbeziehungen zwischen den Verbindungsklassen der Tetrathiocyanatomercurate(II) von Erdalkaliionen und 3d-Metallionen / The Crystal Structures of CaHg(SCN)4 · nH2O (n = 2, 3). Relations between Tetrathiocyanatomercurates(II) of the Alkaline-Earth-Ions and Ions of the 3d-Type
CaHg(SCN)4 · nH2O (n = 2(1), n = 3(2)) were isolated from an aqueous solution of Ca(NCS)2 · 4H2O and Hg(SCN)2· 1 is compared with the analogous MgHg(SCN)4 · 2H2O by means of powder patterns. The crystal structure of 2 has been determined. 2 is monoclinic, space group P21/c with a =9.469(4), b = 22.781(5), c = 6.587(4) Å, β = 93.6(3)°, Z = 4, dc = 2.46 g · cm-3.The structure was refined to R = 7.42 and Rw = 4.96% for 1224 independent reflections.The species MHg(SCN)4 · 2H2O (M = Mg, Ca, Ni) contain nearly tetrahedral Hg(SCN)4 and octahedral M(OH2)2(NCS)4 groups which are joined by Hg-SCN-M bridges.In contrast the structures of the other compounds MHg(SCN)4 · nH2O (M = Co, n = 0; M = Ca, Sr, n = 3) are based on the diamond net. There is tetrahedral coordination of all the metal atoms, M having 4 N and Hg 4 S nearest neighbours. In the hydrates the H2O molecules are situated additionally at the Ca and Sr atoms [*].