Structure, Properties, and Bonding of ZrTe (MnP Type), a Low-Symmetry, High-Temperature Modification of ZrTe (WC Type)

ZrTe (MnP) was synthesized by high-temperature methods at 1570 K in Ta ampules. The structure
of the telluride was determined by means of single-crystal X-ray diffraction to be orthorhombic, Pnma (No.
62), Z = 4, Pearson Symbol oP8, a = 739.15(15) pm, b = 377.23(8) pm, c = 694.34(14) pm. The orthorhombic
MnP type structure is a distorted variant of the NiAs type structure with pronounced metal−metal zigzag
chains. Zigzag chains are typical for phases with a d2 metal atom electron configuration. According to extended
Hückel calculations, the homonuclear interactions in the zigzag chains make up for 2/3 of the Zr−Zr interactions
in ZrTe (MnP) and contribute decisively to the stability of the structure. The emergence of the distorted MnP
type structure instead of the high-symmetry NiAs type ZrTe at high temperatures can be understood as the
result of an optimization of homonuclear Zr−Zr interactions arising from states close to the Fermi level. The
hexagonal WC type ZrTe transforms above 1438 ± 5 K into ZrTe (MnP) (ΔH = 8.3 ± 1.0 kJ mol-1). The
phase transition is reversible, although at room-temperature the reverse reaction is kinetically inhibited. Zr5Te4 and Zr5Te6 are the phases next to ZrTe. ZrTe (MnP) exhibits temperature-independent paramagnetic
properties (χmol = 0.14 × 10-3 cm3 mol-1), as typical for a metallic conductor. Resistivity measurements on
ZrTe (MnP) imply metallic behavior.