Darstellung und Struktur der Phase Li₅Na₂Sn₄ / Preparation and Crystal Structure of Li₅Na₂Sn₄

Abstract

<jats:p>The new compound Li<jats:sub>5</jats:sub>Na<jats:sub>2</jats:sub>Sn<jats:sub>4</jats:sub> crystallizes trigonally, a = 472.3 ± 1 pm, c = 7178 ± 8 pm, space group R3̅m-D<jats:sup>5</jats:sup><jats:sub>3d</jats:sub>. A quarter of the Sn atoms in the unit cell build up a puck­ered net of six-membered rings, another quarter is bound to the net-atoms forming a tetrahedral Sn coordination. The other half of the Sn atoms is ordered in layers of parallel Sn<jats:sub>2</jats:sub> pairs. The nets and layers are separated by the alkali atoms. The structural relations to the variants of the W-structure type of compounds in the system Li-Sn and Na-Sn are shown. </jats:p>

Synthesis and Characterization of A3Na10Sn23 (A = Cs, Rb, K) with a New Clathrate-Like Structure and of the Chiral Clathrate Rb5Na3Sn25

“…The problem was solved by splitting the position to two half-occupied sites, Na5 and Na51, along the long axis of the ellipsoid. Thus, Na51 is further removed from the tetrahedron and is an exo-atom to Sn10 at a short, but not without precedent, distance of 2.98(2) Å. − The other half of this position, Na5, bridges the Sn10−Sn10 edges of the tetrahedron at 3.33(1) Å.…”