Two polymorphs of Ba3Sn2P4: Single crystal and electronic structures

Quaternary Arsenides ACdGeAs2 (A = K, Rb) Built of Ethane-Like Ge2As6 Units

“…The ethane-like Ge 2 As 6 unit is unusual but has been previously observed in GeAs, A 3 Ge 2 As 4 ( A = Ca, Sr), K 5 In 5 Ge 5 As 14 , and K 8 In 8 Ge 5 As 17 . There do exist other [ M x Pn y ] n − ( M = group 13 or 14) pnictide polyanions, such as Sn 2 P 6 12– , which contain formally low oxidation states for M and thus the presence of M – M bonds within these anions, ,− but they remain relatively rare compared to chalcogenide polyanions such as P 2 S 6 4– . The structure of A CdGeAs 2 bears a cursory resemblance to those of K 5 In 5 Ge 5 As 14 and K 8 In 8 Ge 5 As 17 , only to the extent that the latter also consist of layers, but has a much more complicated connectivity of Ge 2 As 6 units, which suffer from partial disordering of Ge and In atoms .…”

“…In both cases, five-membered rings are formed. Changes in the orientation of the dumbbells within the octahedra in the zigzag chains give rise to four- or six-membered rings, as seen in the Sr 3 Si 2 As 4 - and Ba 3 Sn 2 P 4 -type structures. , The relationship between the structures of A CdGeAs 2 and Sr 3 Ge 2 As 4 is more evident if the charge-balanced formula for the former is doubled, ( A + ) 2 (Cd 2+ ) 2 ­(Ge 3+ ) 2 (As 3– ) 4 , and compared to the latter, (Sr 2+ ) 3 ­(Ge 3+ ) 2 (As 3– ) 4 . These formulations provide a simple way to understand the bonding in these compounds.…”

Quaternary Zintl Phases Ba2InSnP3 and Ba2InSnAs3 with Complex Structures and n-Type Semiconducting Behavior

“…Second, both elements have nearly identical covalent radii (1.42(5) Å for In and 1.39(4) Å for Sn) and coordination preferences, which complicates the atomic site assignments based on structural and bonding considerations. The [M 2 Pn 6 ] ethane-like units (M = In, Sn; Pn = P, As), constituting the reported structures, are well-known for both metals and were observed in families of AIn 2 Pn 2 , ,, Ba 2 In 5 Pn 5 , A 3 Sn 2 Pn 4 , ,, and A 14 Sn 3 As 12 compounds (A = Ca, Sr, Ba, Eu; Pn = P, As), to name a few.…”

Crystal and Electronic Structures and Magnetic Properties of Eu3Tt2As4 (Tt = Si, Ge)

“…For Zintl compounds with the nominal A 3 T 2 Pn 4 composition (A = divalent alkaline‐earth or rare‐earth cations; T = d 10 transition metals or triels or tetrels; Pn = pnictogen anions), various polyanion structures have been reported 28–33. Although these ternary phases feature different polyanion units, the structures can all be easily understood by counting the number of bonds and following the octet rule.…”

“…The former exhibits an identical structure to Sr 3 Ge 2 As 4 but one that is different from Sr 3 Si 2 As 4 , which comprises four‐membered rings formed by two Si and two As atoms. A clear explanation for such a structural abnormality is very difficult to make; however, the connection manner of four‐membered rings is relatively rare compared to that of five‐membered rings since the former should have more distorted bond angles for an sp 3 hybridization 33…”