Lanthanoiddisulfide – Synthesen und Kristallstrukturen von α-CeS2, α-NdS2, β-LaS2, β-CeS2 und β-PrS2 / Rare Earth Metal Disulfides – Syntheses and Crystal Structures of α-CeS2, α-NdS2, β -LaS2, β -CeS2, and β -PrS2

Abstract

α-CeS2 and α-NdS2 were obtained by a metathesis reaction of the anhydrous trichlorides LnCl3 (Ln = Ce, Nd) and Na2S2 at 1070 K. The two compounds adopt a monoclinic structure type, the so-called CeSe2 or α-type of the rare earth metal dichalcogenides (space group P21/a), with lattice parameters of a = 8.105(3), b = 4.075(1), c = 8.097(3) Å, β = 90.03(4)◦ for CeS2 and a = 8.008(2), b = 4.019(1), c = 8.032(2) Å , β = 90.00(3)◦ for NdS2. Single crystals of β -LaS2, β -CeS2 and β -PrS2 were obtained as by-products in the syntheses of the ternary copper sulfides CuLnS2 by reacting the elemental educts (Cu, S and Ln = La, Ce, Pr) in a CsCl flux at 970 K. These compounds adopt the orthorhombic β -LaS2 structure type (space group Pnma) with lattice parameters of a = 8.140(1), b = 16.379(1), c = 4.144(1) Å for β -LaS2, a = 8.068(1), b = 16.216(1), c = 4.095(1) Å for β -CeS2, and a = 8.044(1), b = 16.160(1), c = 4.073(1) Å for β -PrS2