Single crystals of MnThTe3 (1) and MgThTe3 (2) grow as small black plates from the stoichiometric reaction of the elements, the former at 1000 °C and the latter at 900 °C with the aid of a Sn flux. Both compounds crystallize in the space group Cmcm of the orthorhombic system with four formula units in cells of dimensions a = 4.2783-(6) Å, b = 13.8618(11) Å, and c = 9.9568(15) Å for 1 and a = 4.2854(6) Å, b = 14.042(2) Å, and c = 9.9450-(14) Å for 2 at T = 153(2) K. KCuThSe3 (3) forms as red blocks from a stoichiometric mixture of K2Se, Cu, Th, and Se at 800 °C, and CsCuThSe3 (4) forms as yellow blocks from a stoichiometric mixture of Cs2Se3, Cu, Th, and Se at 850 °C. Compounds 3 and 4 also crystallize in the space group Cmcm of the orthorohombic system with four formula units in cells of dimensions a = 4.1832(8) Å, b = 14.335(3) Å, and c = 10.859(2) Å for 3 and a = 4.2105(7) Å, b = 15.715(3) Å, and c = 10.897(2) Å for 4 at 153(2) K. Compounds 1 and 2 are isostructural with each other as well as with several uranium analogues and comprise pseudolayered structures with slabs of corner-shared MTe6 octahedra alternating with slabs of cap- and edge-shared ThTe8 bicapped trigonal prisms. The slabs are bonded together through the sharing of edges and vertices of the various polyhedra to form three-dimensional structures. Compounds 3 and 4 are two-dimensional layered structures that are closely related to 1 and 2. In 3 and 4, ThSe6 octahedra form the same slabs as MTe6 in 1 and 2 and Cu atoms occupy the tetrahedral holes in the layers. Alkali metal cations occupy bicapped trigonal prismatic sites between the layers. Neither structure type has short Q - Q interactions, and therefore the oxidation states of all atoms are straightforwardly assigned on the assumption of Th4+. Magnetic susceptibility measurements on compound 1 show a ferromagnetic transition at 70 K and a magnetic moment of 5.9(2) μ(B) per Mn ion, indicating low-spin Mn2+.
ASJC Scopus subject areas
- Physical and Theoretical Chemistry
- Inorganic Chemistry