The new ternary chalcogenides zirconium germanium tetratelluride (ZrGeTe4), hafnium germanium tetratelluride (HfGeTe4), and titanium germanium hexatelluride (TiGeTe6) have been synthesized, and their structures have been determined by single-crystal X-ray diffraction methods. The compounds ZrGeTe4 and HfGeTe4 are isostructural. They crystallize in space group C122v of the orthorhombic system with four formula units in cells of dimensions a = 3.976(4), b = 15.876(16), c = 10.948(12) Å (ZrGeTe4) and a = 3.963(3), b = 15.875(10), c = 10.941(7) Å (HfGeTe4) at 113 K. The compound TiGeTe6 crystallizes in space group C32h of the monoclinic system with four formula units in a cell of dimensions a = 13.972(26), b = 3.909(9), and c = 17.454(32) Å and β = 104.95(5)° at 113 K. These compounds adopt new layered structure types, in which the basic structural building blocks are metal-centered bicapped trigonal prisms, one of whose caps is a GeTe3 trigonal pyramid. The structure of MGeTe4 (M = Zr, Hf) consists of true two-dimensional layers [formula omitted] while that of TiGeTe6 consists of one-dimensional chains [formula omitted] that are weakly linked together by long Te-Te bonds to form a layer. Structural interrelationships among these compounds and some binary chalcogenides are presented. The compounds ZrGeTe4 and HfGeTe4 are semiconductors; they are probably nonstoichiometric. The compound TiGeTe6 appears to undergo a metal-to-semiconductor transition below 165 K. Extended Hückel band-structure calculations are used to rationalize the physical properties and bonding features in these compounds.
ASJC Scopus subject areas
- Colloid and Surface Chemistry