K₁₀Ga₃Bi_6.65 – The First Compound in the Ternary A‐Ga‐Bi System Comprising Cyclic Tris‐meta Borate‐Analogous [Ga₃Bi₆]^9– Units and Bi₂ Dumbbells

Abstract

K10Ga3Bi6.65 is the first representative in the ternary system A‐Ga‐Bi (A = alkali metal). It contains [Ga3Bi6]9– anions with planar triangular‐coordinated Ga atoms as the main structural feature, accompanied by isolated Bi–Bi dumbbells. Alkali metal cations are counterbalancing the charges and fill the space between the anionic units. According to the Zintl‐Klemm concept charge balance is reached if an almost equal ratio of single and double‐bonded Bi2 dumbbells are present according to (K+)10[Ga3Bi6]9–([Bi‐Bi]4–)1/6([Bi=Bi]2–)1/6.

K7In4As6 and K3InAs2 ‐ Two more Zintl phases showing the rich variety of In‐As polyanion structures

“…Synthesis. K 7 In 4 As 6 , was obtained, similar to the recently reported compound K 10 Ga 3 Bi 6.65 , [9] first from the elements in a quaternary sample K, Cu, In and As with the ratio 1 : 1 : 0.9 : 1.5 (61.2 mg K, 99.4 mg Cu, 163.6 mg In and 175.8 mg As; sample 1). The aim of this synthesis was to obtain a compound, similar to Na 12 Cu 12 Sn 21 , substituting Sn with a mixture of In and As.…”

“…With the highest amount of alkali metals, isolated trigonal fragments [TrPn 3 ] 6À such as [InAs 3 ] 6À [4] and associated dimers, trimers or condensed five-membered rings such as [Ga 2 P 4 ] 6À , [5] [Ga 3 As 6 ] 9À , [6] and À [Ga 2 As 3 ]À [7] occur on one hand, or discrete tetrahedral [TrPn 4 ] 9À units [8] such as [AlP 4 ] 9À [8a] as well as related dimers, linear or two-and three-dimensional polymers occur on the other hand. Notice, that in case of the basic unit [TrPn 3 ] 6À mesomeric forms with Tr-Pn double bonds support the planarity of the [TrPn 3 ] unit, and such units are even found among the heavier homologues of the Tr and Pn elements such as Ga and Bi, [9] which is in contrast to the well-known 'double bond rule'. [10] The [TrPn 3 ] units might be interconnected in different ways by sharing edges, faces, corners, to build up three dimensional structures.…”

“…Recently, K 10 Ga 3 Bi 6.65 has been reported containing linked trimers of [GaBi 3 ] units forming slightly deformed hexagonal [Ga 3 Bi 6 ] 9À polyanions with planar triangular-coordinated Ga by Bi atoms beside isolated BiÀ Bi dumbbells. [9] Among these structures, the nature of the anionic framework is collectively related to the number, the size, and the charge of the cations and, in turn, to the atomic ratio and thus the charge of the [Tr x Pn y ] zÀ anion and its valence electron concentration. Consequently, with a smaller amount of alkali metal and thus Tr-Pn polyanions with lower charge of the general composition [Tr x Pn y ] zÀ exhibit one-, two-or threedimensional anionic frameworks with decreasing alkali metal content.…”

Between Elemental Match and Mismatch: From K12Ge3.5Sb6 to Salts of (Ge2Sb2)2−, (Ge4Sb12)4−, and (Ge4Sb14)4−

“…Single-stranded substructures were observed in other intermetallic solids, for instance in Pr 6 Ni 1.76 Si 3 , [24a] Pr 5 Ni 1.9 Si 3 , [24b] Ce 6 Ni 2 Si 3 , [25] Nd 6 Co 1.67 Si 3 , [26] Pr 6 Co 1.67 Si 3 , [27] K 10 Ga 3 Sb 6.33 , [28] K 10 Ga 3 As 6.33 , [28] and K 10 Ga 3 Bi 6.65 , [29] some of which were also interpreted as line-up of disordered dumbbells.…”

The Gallate Pnictides Ba9[GaO4]3Pn (Pn=Sb, Bi) and a Partially Oxidized Zintl Anion in Ba2[GaO2As]

“…The compound Ba 9 [GaO 4 ] 3 Bi ( 2 ) first was serendipitously obtained in an attempt to synthesize ternary Zintl phases in the ternary system Ba/Ga/Bi [23] . The used Ba metal turned out as contaminated with an oxide layer.…”