Strukturelle und elektronische Flexibilität in Hydriden von Zintl‐Phasen mit Tetrel‐Wasserstoff‐ und Tetrel‐Tetrel‐Bindung

Abstract

Die Hydrierung von Zintl-Phasen ermçglicht die Bildung neuer Strukturmotive mit Hauptgruppenelement-Wasserstoff-Bindungen im Festkçrper.

Determination of element–deuterium bond lengths in Zintl phase deuterides by2H-NMR

“…As the structural properties of the materials under consideration are crucial for the interpretation of their NMR results, we will first review the crystallographic details that are published already elsewhere. [20][21][22][23][24] Within the homologue series of the Zintl phase deuterides AeTtD (1+y) , Ae = Ca-Ba, Tt = Si-Sn, three distinct structure types occur ( Fig. 1).…”

“…The remaining Tt atoms are bound to deuterium. Furthermore, diffraction showed that the chain-coordinating deuterium site is always under-occupied (details were given elsewhere [22][23][24] ) which is indicated by a correction term x in the chemical formula. The compounds CaSiD 4/3Àx , 20,21…”

“…The Zintl phases were prepared by stoichiometric mixtures of the respective elements using tantalum metal jackets which were subsequently sealed and placed in fused silica ampoules at reduced pressure. The deuterides were prepared in a Nicrofer 5219Nb-alloy 718 autoclave at typical D 2 gas pressures of 5 to 9 MPa and 473 K. Details are given elsewhere (SrSiD 5/3 and BaGeD 5/3 ; 23,24 BaSiD 2 , SrGeD 4/3 and BaSnD 4/3…”

“…On the basis of the general similarities of the crystal structures investigated within this work, i.e. a high symmetry environment (cubic pseudo-symmetry) and a low symmetry environment (no pseudo-symmetry) for D atoms, 23,24 we find consistently with our report on BaSiD 2Àx and SrGeD 4/3Àx , 22 that the narrow resonance lines in Fig. 2 can be assigned to 2 H nuclei residing in the Ae 4 voids (high symmetry), whereas the quadrupolar split ones belong to Tt chain sites (low symmetry).…”

“…3 22 as well as SrSiH 1.5 and BaGeH 1.6 . 23,24 The compounds exhibit hydride anions in tetrahedral cationic voids and additional hydrogen binding to the polyanion. Due to short bond lengths, there is strong indication for a covalent interaction, but the estimated uncertainties of a Rietveld based analysis are rather high.…”