Anette Imre

ScPtP und LaPtP – Zwei Phosphide mit ,,inverser“ TiNiSi-Struktur / ScPtP and LaPtP – Two Phosphides with “Inverse” TiNiSi-Type Structure

Single crystals of ScPtP (orthorhombic, a = 6.437(1), b = 4.291(1), c = 7.550(2) Å ) were grown by reaction of the elements in molten lead (1000 °C), whereas LaPtP (orthorhombic, a = 7.268(1), b = 4.532(1), c = 7.864(2) Å ) was prepared by heating mixtures of the elements at 900 °C. Both phosphides were investigated by single crystal X-ray diffraction. Their crystal structures belong to the TiNiSi-type (Pnma; Z = 4), but the positions of the Ni and Si atoms are exchanged. Therefore the Pt atoms are located in the centers of trigonal prisms and the P atoms are coordinated by four Pt atoms in the shape of distorted tetrahedra.

Synthese und Kristallstrukturen von Seltenerdmetall-Antimoniden des Palladiums / Synthesis and Crystal Structures of Antimonides of Rare-Earth Metals and Palladium

The new compounds Pr3Pd6Sb5 (a = 13.442(3), b = 4.442(1), c = 9.994(2) Å ), Nd3Pd6Sb5 (a = 13.412(3), b = 4.431(1), c = 9.962(2) Å), and Gd3Pd6Sb5 (a = 13.293(2), b = 4.397(1), c = 9.881(2) Å) are isotypic and crystallize with the Ce3Pd6Sb5 type structure (Pmmn; Z = 2). The rare-earth metal atoms are arranged in form of three pseudo-body-centered subcells, whereas Pd and Sb atoms form a three-dimensional arrangement derived from the well-known ThCr2Si2 and CaBe2Ge2 structures. GdPdSb (a = 4.566(1), c = 7.444(1) Å) and DyPdSb (a = 4.545(1), c = 7.354(1) Å) crystallize with an ordered variant of the CaIn2 type structure (P63mc; Z = 2), also called as LiGaGe type, with slightly puckered hexagon nets of Pd and Sb atoms, which trigonally coordinate each other. In this series a decreasing radius of the rare-earth metal allows a tetrahedral non-metal environment of the Pd atoms and accordingly ScPdSb (a = 6.310(1) Å) forms the MgAgAs type structure (F4̄3m; Z = 4), a filled variant of the sphalerite type. The antimonides were prepared by heating mixtures of the elements at 600 °C and subsequent annealing at 900 - 1100 °C. Their structures have been determined by single-crystal X-ray methods.

Kristallstrukturen mit Bausteinen des CaBe2Ge2-Typs – Die Verbindungen Sm2Pt6P3 und Ca2Pd3Sb4 / Crystal Structures with CaBe2Ge2-Type Units – The Compounds Sm2Pt6P3 and Ca2Pd3Sb4

Single crystals of Sm2Pt6P3 (a = 4.095(1), c = 45.313(9) Å ) were prepared by heating the elements in a melt of NaCl/KCl at 1100°C. The compound crystallizes with a new tetragonal type of structure (I41/amd; Z = 4) consisting of units which correspond to the CaBe2Ge2 type except for one significant difference: In the layer of PPt4 tetrahedra only two of four P positions are occupied. Therefore this layer is built up by corner- instead of edge-sharing PPt4 tetrahedra. Four of these units are stacked along [001]. Single crystals of Ca2Pd3Sb4 (a = 4.506(1), c = 41.538(8) Å ) were obtained by reaction of the elements at 900°C. The crystal structure (I4/mmm; Z = 4) consists of two blocks. The first one has the composition CaPd2Sb3 and can be derived from the CaBe2Ge2 type. In the second one (formula CaPdSb) the atoms are arranged analogous to the CeMg2Si2 type. Both blocks alternate along [001]