Inhaltsu È bersicht. La 3 Cl 2 Si 3 und La 6 Br 3 Si 7 werden bei ∼ 950 °C aus LaX 3 (X = Cl, Br), La-Metall und Si dargestellt. Nach der Einkristallstrukturanalyse kristallisiert La 3 Cl 2 Si 3 in C2/m mit a = 1802(3), b = 420.6(4), c = 1058(2) pm, b = 97.9(2)°und La 6 Br 3 Si 7 in Pmmn mit a = 1686.9(2), b = 412.93(11), c = 1185.2(1) pm. In beiden Verbindungen befinden sich die Si-Atome in trigonalen Prismen aus La-Atomen, die u È ber gemeinsame Dreiecks-und Rechteckfla Èchen zu Ebenen verknu È pft sind. Sie werden u È ber die Halogenatome miteinander verknu È pft. In La 3 Cl 2 Si 3 bilden die Si-Atome Si-Ketten, in La 6 Br 3 Si 7 Stra È nge aus 1 ∞ -kondensierten Si 12 -Ringen. Beide Verbindungen besitzen metallische Leitfa È higkeit.
Zintl Anions of Silicon in the Halides La 3 Cl 2 Si 3 and La 6 Br 3 Si 7 Abstract. La 3 Cl 2 Si 3 and La 6 Br 3 Si 7 are prepared at temperatures of around 950 °C from LaX 3 (X = Cl, Br), La metal and Si as starting materials. La 3 Cl 2 Si 3 crystallizes in C2/m with a = 1802(3), b = 420.6(4), c = 1058(2) pm, b = 97.9(2)°, and La 6 Br 3 Si 7 in Pmmn mit a = 1686.9(2), b = 412.93(11), c = 1185.2(1) pm. In both compounds the Si atoms are located in trigonal prisms of La atoms, which are connected through common triangular and rectangular faces to form layers. The bromine atoms connect the metal atom double layers. In La 3 Cl 2 Si 3 the Si atoms form zig-zag chains, in La 6 Br 3 Si 7 chains build up from 1 ∞ -connected Si 12 rings. Both compounds are metallic conductors.