Na₂[SnAs₂], die erste Zintl-Phase mit einem [SnAs₂]-Raumnetz aus adamantan-analogen [Sn₄As₁₀]-Einheiten / Na₂[SnAs₂], the First Zintl Phase with a [SnAs₂] Framework Based on Adamantan Analogous [Sn₄As₁₀] Units

Abstract

The metallic grey compound Na2[SnAs2] was prepared from a molten mixture of the elements. Na2[SnAs2] crystallizes in the tetragonal space group I41/acd, Z = 32, with the lattice constants: a = 1416.6(3) pm, c = 2119.1(4) pm, c/a = 1.4959.In the crystal structure four [SnAs4] tetrahedra are connected by common corners forming adamantan analogous [Sn4As10] units. The further connection of these tetrameric moieties by the terminal As atoms results in a three-dimensional framework ∞3[SnAs22-], in which the Na atoms occupy distorted tetrahedral and octahedral holes.

Ternary arsenides ATt3As3 (A=K, Rb; Tt=Ge, Sn) with layered structures

“…Previously known ternary phases were limited in the A-Ge-As (A = alkali metal) systems (Li 1.67 Ge 0.33 As, A 5 GeAs 3 (A = Na, Cs), K 2 GeAs 2 ) [11,[23][24][25] but more numerous in the A-Sn-As systems (NaSn 2 As 2 , A 2 SnAs 2 (A = Na, K, Rb), A 5 SnAs 3 (A = Na, K), KSnAs, K 6 Sn 3 As 5 ) [7,[12][13][14]19,[25][26][27][28]. The isostructural arsenides ATt 3 As 3 (A = K, Rb; Tt = Ge, Sn) are new phases in these systems.…”

“…The vast majority of these structures contain simple anionic units with the normal oxidation states adopted by all atoms (A + , Tt +4 , Pn -3 ). The most common are Tt-centred tetrahedra that can be isolated (e.g., Na 8 SnSb 4 -type) [6], corner-sharing (e.g., Na 2 SnAs 2 -and Na 5 SnSb 3 -types) [7,8], or edge-sharing (e.g., Na 5 GeP 3 -and K 2 SiP 2 -types) [9,10]. Isolated Ttcentred trigonal planes are found in the Cs 5 SiP 3 -type [11].…”

Frameworks for Extended Solids: Geometrical Design Principles

“…Two collapsed decorated nets with ¹}X}¹"109.53 interpenetrate (the symmetry is now I4 /acd) and again the X arrangement is ccp so an &&open'' structure is not achieved. Other examples of interpenetrated networks of the same structure are -Ca Ga N (37) and Na SnAs (38), in which Ca or Na are in the interstices between the interpenetrating nets.…”

LiSi3As6and Li2SiAs2with flexible SiAs2polyanions: synthesis, structure, bonding, and ionic conductivity

“…142) in the same structure type as Na 2 SnAs 2 and Li 2 SiP 2 . 17,18,63 Adamantane-like Si 4 As 10 units are connected to each other through shared As atoms (Fig. 4).…”