Komplexe Chalkogenide der IVa Metalle mit niedrigdimensionalen anionischen Partialstrukturen. Darstellung und Kristallstruktur von K2ZrTe3 und Rb2ZrTe3

The isostructural compounds K2ZrTe3 and RbZrTe3 were obtained at 1000?C by reacting K2Te and Rb2Te with stoichiometric amounts of Zr and Te. The compounds are monoclinic, mP24, space group P21/c, Z=4 with a=9.089(3), b=14.148(4), c=6.986(3)Ä, ß=105.90(1)? and a=9.735(4), b=14.300(7), c=6.952(8)Ä, ß=108.61(2)?, respectively. The crystal structure was determined from diffractometer data and refined to R=0.030 for 1452 Fo's for K2ZrTe3 and R=0.038 for 1131 Fo's for Rb2ZrTe3. The crystal structure is of a new type, characterized by infinite anionic chains, 1-00-[ZrTe3](2-) built up by octahedra sharing opposite faces which run along [001]. The mean Zr-Te bond lengths are 2.921 and 2.920Ä, respectively. The alkali cations separating the chains are characterized by two different-distorted octahedral and pentagonal bipyramidal-chalcogen environments.