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Keywords:

  • Tellurium;
  • Selenium;
  • Zinc;
  • Manganese;
  • Amines;
  • Solvothermal synthesis

Abstract

The novel chalcogenidotellurates(IV) [Zn(NH3)6][Zn(NH3)4]2(TeS3)3 (1), [Zn(NH3)4](TeSe3) (2), [Mn(NH3)6](TeS3) (3), [Mn(NH3)6](TeSe3) (4) and [Mn(CH3NH2)6](TeSe3) (5) were obtained by solvothermal reactions from elemental zinc or manganese, tellurium and sulfur or selenium, respectively, in liquid ammonia or methylamine. The reactions were performed in thick-walled glass ampoules at 50 °C and give 1, 2 and 3 in quantitative yield. The yields for 4 and 5 are lower. The crystal structures consist of tetrammine, hexammine and hexakis(methylamine) complexes of divalent Zn and Mn and of trigonal-pyramidal (TeCh3)2– (Ch = S, Se) anions. Compounds 1 (P31m) and 2 [two polymorphic forms, Cmc21 (2a) and Pca21 (2b)] crystallise in a noncentrosymmetric manner in polar structures, while 3 (P21/c), 4 (Pbca) and 5 (P21/m) are centrosymmetric. As an unique feature, the structure of 1 contains two different types of Zn ammine complexes, tetrahedral [Zn(NH3)4]2+ and octahedral [Zn(NH3)6]2+. Compound 5 contains the rare hexacoordinate complex [Mn(CH3NH2)6]2+. Raman spectra of 1 and 2 show the two expected symmetric and asymmetric valence vibrations between 350–380 cm–1 for (TeS3)2– and 215–235 cm–1 for (TeSe3)2–.