The new complex lanthanum tetrelide La55Sn36.6Ge24.4

Dürr, Ines; Röhr, Caroline

doi:10.1016/j.jallcom.2011.10.090

Cited by 6 publications

(4 citation statements)

References 41 publications

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“…Folgerichtig sind in den gemischten Tetreliden vor allem die planaren Ketten und Kettenstücke, aber auch die Sechsringe in der neuen Titelverbindung III, diejenigen Bauelemente, in denen eine statistische Sn/Ge-Besetzung auftritt. Dabei kommt es, wie die komplexen Kettenstücke in IV zeigen, zu einer leichten, von der Ge/Sn-Besetzung abhängigen Anpassung der M-Umgebung (Koordinationszahlen und Abständen) und der Kettenkonformation [8]. Das elektronegativere Germanium besetzt in Kettenstücken bevorzugt die terminalen Positionen (s. dazu (b)); lineare Bereiche der Ketten werden dagegen von Sn-Atomen eingenommen (s. (c)).…”

Section: La Launclassified

Neue Lanthan-Stannide/Germanide: La₃Sn_4.4Ge_0.6, La₃Sn_3.1Ge_0.9 und La₉Sn_6.7Ge_3.3 / New Lanthanum Stannide/Germanides: La₃Sn_4.4Ge_0.6, La₃Sn_3.1Ge_0.9 and La₉Sn_6.7Ge_3.3

Dürr

Röhr

2011

Zeitschrift Für Naturforschung B

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Three new ternary mixed lanthanum stannide/germanides have been synthesized and characterized in the course of a systematic study of the phase formation at the 3 : 5, 3 : 4 and 1 : 1 pseudo-binary sections of the ternary system La -Ge -Sn, i. e. a study of the 'coloring' in mixed tetrelides. The structures of the title compounds have been determined using single-crystal X-ray data, and the electronic structure was analyzed by means of simple electron counting rules and FP-LAPW band structure methods. Even a very minor substitution of Sn by Ge in the 3 : 5 stannide La 3 Sn 5 already changes the structure from the Pu 3 Pd 5 type of the binary stannide towards the Tl 4 PbTe 3 type (La 3 Sn 4.4 Ge 0.6 : tetragonal, space group I4/mcm, a = 861.35(10), c = 1211.48(13) pm, Z = 4, R1 = 0.0420). According to the anionic building blocks present, isolated [Ge/Sn] 4− anions and heavily puckered 4.8 2 nets of three-bonded tin atoms (i. e. [Sn 4 ] 4− Zintl ions), a small formal electron excess (+9/ − 8) occurs, which is also apparent from the position of the minimum in the calculated tDOS. In contrast, starting from the known binary stannide La 3 Sn 4 (orthorhombic, space group Cmcm, Er 3 Ge 4 structure type) a substitution of tin by germanium is possible without a change of the structure type up to the border composition La 3 Sn 3.1 Ge 0.9 (a = 448.61(5), b = 1170.68 (14), c = 1556.0(2) pm, Z = 4, R1 = 0.0380). Germanium preferentially occupies the sites of the [Ge/Sn] 3 trimers, whereas the site of the square-planar coordinated Sn(3), which is stabilized by hypervalent bonding, is not populated by germanium. Taking the respective partial bonding into account, the Zintl electron count is also nearly exact (+9/ − 8). The new complex mixed tetrelide La 9 Sn 6.7 Ge 3.3 (tetragonal, space group P4 2 /ncm, a = 1602.04(3), c = 1724.42 (5) [M 6 ]. In this compound, the electron count following the Zintl concept also reveals only a very small formal excess of electrons (+54/ − 52).

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Section: La Launclassified

Neue Lanthan-Stannide/Germanide: La₃Sn_4.4Ge_0.6, La₃Sn_3.1Ge_0.9 und La₉Sn_6.7Ge_3.3 / New Lanthanum Stannide/Germanides: La₃Sn_4.4Ge_0.6, La₃Sn_3.1Ge_0.9 and La₉Sn_6.7Ge_3.3

Dürr

Röhr

2011

Zeitschrift Für Naturforschung B

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“…Inbetween the Ln:M composition 1:1 and 3:5 ternary mixed stann-/german-ides exhibit a wide variety of different compositions and structures not known from any binary border phase. These mixed tetrelides of compositions 55:61 (La 55 Sn 36.6 Ge 24.4 [1]), 9:10 (La 9 Sn 6.7 Ge 3.3 [2] and Gd 9 Sn 6.1 Ge 3.9 ), 3:4 ((La/Gd) 3 Sn 0.9 Ge 3.1 , Er 3 Ge 4 type), 2:3 (Yb 2 SnGe 2 , Mo 2 FeB 2 type) and 3:5 (La 3 Sn 4.4 Ge 0.6 [2], La 3 In 4 Ge type) exhibit only small deviations from the Zintl electron count. Their complex structures show different M anions/bonding modes e.g.…”

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confidence: 99%

“…[1] Müller, U. Starting from the extremely rich but quite diverse structural chemistry of binary lanthanum tetrelides, ternary mixed La stann-ides/germanides have been synthesized which not only present substitutional variants of the binary border phases, but also themselve form new singular structure types [1,2]. This work was now extended to the heavier rare earth elements (Ln) Gd (smaller ionic radius) and Yb (flexible valency), and the alkaline earth ele-ments Ca, Sr and Ba (A), which form mostly electron precise Zintl phases (black symbols).…”

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confidence: 99%