The first nitridogermanates(III) Ca6[Ge2N6] and Sr6[Ge2N6] were synthesized from sodium flux and structurally characterized by powder and single crystal X‐ray diffraction, respectively. They crystallize isostructurally to each other and homeotypic to Ca6[Cr2N6]H in space group Rtrue3‾
. They feature unprecedented, mutually isolated, ethane‐like [GeIII2N6]12− anions in a staggered conformation. The compounds are semiconductors according to resistivity measurements and electronic structure calculations, yielding band gaps of 1.1 eV for Ca6[Ge2N6] and 0.2 eV for Sr6[Ge2N6].
Black single crystals with metallic luster of (Sr3N2/3–x)E (E = Sn, Pb) and (Sr3N)Sb were grown in lithium flux from strontium nitride, Sr2N, and tin, lead, or antimony, respectively. Nitrogen deficiency in the tin and the lead compound is a result of the higher ionic charge of the tetrelide ions E4– as compared to the antimonide ion Sb3–. In contrast to microcrystalline samples from solid state sinter reactions obtained earlier, the flux synthesis induces nitrogen order in the nitrogen deficient tetrelides. The antimony compound crystallizes as inverse cubic perovskite [a = 517.22(5) pm, Z = 1, space group Pm3m, no. 221] with fully occupied nitrogen site, whereas the nitrogen deficient tin and lead compounds exhibit partially ordered arrangements and a certain phase width in respect to nitrogen contents. For the tetrelides, the nitrogen order leads to a cubic 2 × 2 × 2 superstructure [E = Sn: a = 1045.64(8) pm for x = 0, a = 1047.08(7) pm for x = 0.08; and E = Pb: a = 1050.7(1) pm for x = 0, space group Fm3m, no. 225] as derived from single‐crystal X‐ray diffraction data. The metallic tetrelides show diamagnetic behavior, which is consistent with electronic structure calculations.
Abstract. Large single crystals of Li 2 (Ca 3 N) 2 [Ga 4 ] and Li 2 (Sr 3 N) 2 [Ga 4 ] up to several mm in size were grown from mixtures of the respective elements and binary alkaline-earth metal nitrides in reactive lithium melts employing a modified high-temperature centrifugation-aided filtration (HTCAF) technique. The main structural features of these iso-
Die ersten Nitridogermanate(III) wurden in Form der Verbindungen Ca 6 [Ge 2 N 6 ]u nd Sr 6 [Ge 2 N 6 ]m ithilfe von Natrium als Flussmittel synthetisiert und durch Rçntgenbeugung am Pulver beziehungsweise am Einkristall charakterisiert. Ca 6 [Ge 2 N 6 ]u nd Sr 6 [Ge 2 N 6 ]k ristallisieren isostrukturell zueinander und homçotyp zu Ca 6 [Cr 2 N 6 ]H in der Raumgruppe R3.S ie weisen neuartige,v oneinander isolierte,E thananaloge [Ge III 2 N 6 ] 12À-Anionen in gestaffelter Konformation auf.W iderstandsmessungen und Berechnungen der elektroni-schenS truktur zufolge handelt es sich um Halbleiter mit Bandlücken von 1.1 eV fürC a 6 [Ge 2 N 6 ]u nd 0.2 eV für Sr 6 [Ge 2 N 6 ]. Einleitung Die binären Nitride der schwereren Te trele Silicium, Germanium, Zinn und Blei folgen im Hinblick auf die Stabilitätd er Te trel-Stickstoff-Bindung einem klaren Tr end. Siliciumnitrid, Si 3 N 4 ,ist eine wohlbekannte,hochgradig inerte Verbindung,w elche sich erst bei Te mperaturen über 1500 8 8C merklich thermisch zersetzt. [1] Aufgrund seiner Härte und thermischen Stabilitätk ommt es in vielen Industrie-und Spezialanwendungen zum Einsatz. Auch Germaniumnitrid, Ge 3 N 4 ,zählt zu den eher stabilen Nitriden, zersetzt sich aber bereits bei ca. 600 8 8CimV akuum. [2] Die Kristallstrukturen der Niederdruckdruckmodifikationen sowohl von Silicium-als auch von Germaniumnitrid bestehen aus dreidimensionalen Netzwerken kondensierter SiN 4-b ezeihungsweise GeN 4-Tetraeder.V on beiden Nitriden existieren Hochdruckmodifikationen im Spinell-Typ, [3, 4] in denen zwei Drittel der Te trel-Atome oktaedrisch von Stickstoff koordiniert werden. Für Zinnnitrid, Sn 3 N 4 ,w urde bisher ausschließlich diese Modifikation beobachtet. Sie lässt sich bei Atmosphärendruck gewinnen, fängt aber schon bei Te mperaturen von 300 8 8C an, sich zu zersetzen. [5] Soweit wir wissen, wurde die Existenz von Bleinitrid bisher nicht nachgewiesen. Im Hinblick auf ternäre Nitride ist Germanium aufgrund der mittleren Stabilitätd er Germanium-Stickstoff-Bindung
Large black single crystals with a metallic luster of Li16Sr6Ge6N and several other representatives of the series Li16Ae6Tt6N and Li16Ae6Tt6.5 (Ae=Ca, Sr; Tt=Si, Ge, Sn, Pb) were grown from mixtures of the respective elements with addition of binary alkaline‐earth metal nitrides or lithium nitride in the case of the nitrides. For the synthesis a modified high‐temperature centrifugation‐aided filtration (HTCAF) technique using reactive lithium melts was employed. These metallic phases crystallize in an ordered defect‐variant of the Sc11Ir4 type with selective occupation of the smaller octahedral voids in the origin (000) with N and the larger rhombic dodecahedral voids in (00
1/2
${{ 1/2 }}$
) with Tt. Charge balance assuming the presence of exclusively closed shell ions for all examples accounts for an electronic excess. Diamagnetism despite metallic properties is consistent with results from electronic structure calculations.
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