Li₃BS₃ und LiSrBS₃: Neue Orthothioborate mit trigonal‐planar koordiniertem Bor

Abstract

Professor Wolfgang Jeitschko zum 60. Geburtstag gewidmet Inhaltsiibersicht. Es wird iiber die beiden Orthothioborate Li,BS, (Pnma; a = 8,144(1) A, b = 20,063(2) A, 6,161(1) A; Z = 4) und LiSrBS, (Pnma; a = 7,557(1) A, b = 9,083(2) A, c = 7,049(1) A; Z = 4) berichtet. Die beiden neuen Phasen wurden durch Hochtemperatur-Schmelzreaktion aus den Metallsulfiden, amorphem Bor und Schwefel bei 700 "C darge-Li,BS, and LiSrBS,: New Orthothioborates wi Abstract. We report o,n the two new orthothioborates Li,BS, (Pnma; a = 8.144(1) A, b = 10.063(2) A, 6.161(1) A; Z = 4) and LiSrBS, (Pnma; a = 7.557(1) A, b = 9.083(2) A, c = 7.049(1) A; Z = 4). The two new phases were prepared by reaction of the metal sulfides, amorphous boron, and sulfur at 700 "C. Both compounds contain isolated, planar [BS,]'--stellt. Beide Verbindungen enthalten isolierte, planare [BS,]'--Anionen. Die Lithiumionen sind vierfach (Li3BS3) bzw. sechsfach (LiSrBS,) von Schwefel umgeben, das Strontiumion weist eine achtfache Schwefelkoordination auf. Li,BS, und LiSrBS, bilden neue A3BX3 bzw. AA ' BX,-Strukturtypen. h Trigonal Planar Boron Coordination anions. The lithium ions have fourfold (Li,BS,) and sixfold (LiSrBS,) sulfur coordination, the strontium ion shows an eightfold sulfur coordination. The two compounds represent new A,BX, resp. AA'BX, structure types.

Syntheses, Crystal Structures, and Properties of the Novel Thioborates KBa4(BS3)3 and K4Ba11(BS3)8S

“…The B±S bond lengths are similar to those found in other orthothioborates, e. g. the average bond length calculates to 1.823 A Ê being only slightly smaller than the one observed for Li 3 BS 3 (1.830 A Ê ) [6,7]. In the BS 3 entities the deviation from the ideal D 3h symmetry is remarkable with S±B±S angles ranging from 116.7(3)°up to 125.7(3)°.…”

“…The samples were prepared under dry argon in a glove box. Significant absorption bands occur at 821 cm ±1 and 788 cm ±1 , which can be assigned to antisymmetrical stretching modes in accordance to the m as frequencies reported e. g. for LiSrBS 3 [7], LiBaBS 3 [8] or Na 3 BS 3 [27].…”

“…Therefore a structural similarity to other known orthothioborates such as LiSrBS 3 [7], LiBaBS 3 [8], Ba 3 (BS 3 ) 2 [22,24], Sr 3 (BS 3 ) 2 [23,24], Li 3 BS 3 [6,7], and Tl 3 BS 3 [9] is observed for the two novel compounds. For K 4 Ba 11 (BS 3 ) 8 S, additional sulfide anions revealing only electrostatic interaction to barium cations are found.…”

“…5 a and 5 b, dihedral angles of 60.4°and 82.5°are observed. In general, orthothioborates show different arrangements of such layers with dihedral angles of 79.9°in LiSrBS 3 [7] and 42.8°in Li 3 BS 3 [6] down to a parallel arrangement in Tl 3 BS 3 [9] and Sr 3 (BS 3 ) 2 [23,24]. The additional sulfur atom S(5) is located on the three-fold rotation inversion axis with six barium atoms forming an ideal octahedron as the coordination polyhedron (see Figs.…”

“…Binary boron sulfides and selenides [1, 3±5] [8, 12±14] which are characteristic structural features in chalcogenoborates of alkali and alkaline earth metals. It is well known that in addition to large cations such as strontium and barium, smaller alkali ions, especially lithium, can be incorporated in thioborate structures [7,8,15]. This is of special importance for the physical properties of these compounds, e. g. for the ionic conductivity observed in some lithium thioborates [16,17].…”