Alkalimetalltetraethinylozincate und ‐cadmate A^I₂M(C₂H)₄ (A^I = Na — Cs, M = Zn, Cd): Synthese, Kristallstruktur und spektroskopische Eigenschaften

Abstract

Durch Reaktion von AIC2H (AI = Na — Cs) mit zweiwertigen Zink‐ und Cadmium‐Salzen in flüssigem Ammoniak konnten die Alkalimetalltetraethinylozincate und ‐cadmate AI2M(C2H)4 (M = Zn, Cd) als polykristalline Pulver dargestellt werden. Während Na2M(C2H)4 röntgenamorph ist und die Kristallstruktur von Cs2Zn(C2H)4 bislang noch nicht aufgeklärt werden konnte, sind die restlichen Verbindungen nach Beugungsuntersuchungen am Pulver mit Röntgen‐ und Synchrotronstrahlung isotyp zu den strukturell bereits bekannten Kaliumverbindungen. Sie kristallisieren in der tetragonalen Raumgruppe I41/a, enthalten [M(C2H)4]2—‐Tetraeder und zeigen strukturelle Verwandtschaften zum Scheelit und Anatas. Raman‐spektroskopische Untersuchungen belegen das Vorliegen eines Tetraederfragmentes mit C‐C‐Dreifachbindungen in den Alkalimetall‐ wie auch in den röntgenamorphen Erdalkalimetallverbindungen AIIM(C2H)4 (AII = Mg — Ba, M = Zn, Cd).

Assembly of ethylzincate compounds into supramolecular structures

“…Still it is different, since the carbon atoms bearing the negative charge coordinate to one zinc atom only, and supramolecular linking is caused by a second functionality of the ligand in contrast to 1. In rubidium tetra(ethynyl)zincate, four ethynyl-groups radiate linearly from a tetrahedral zinc atom [35]. Each ethynyl ligand is surrounded by three Rb þ ions coordinated to the ethynyl p-systems.…”

Reconfirmation of Solubility of C22− in Liquid Ammonia: Syntheses and Crystal Structures of the Tetrahedral Acetylide Ammoniates [Zn(C2H)4]2−, [Cd(C2H)4]2− and [In(C6H5)3(C2H)] −

“…All other geometric parameters are in good agreement with values reported for the compounds K 2 Zn(C 2 H) 4 • 2NH 3 and Rb 2 Zn(C 2 H) 4 . [17,12] The overall negative charge of 2À is compensated by two [Cs( [18]crown-6)] cation complexes, which are identical generated by symmetry. The chelate molecule shows rotational disorder which can be modelled by splitting atoms and adding different occupation factors (for values see table S1.7 in the SI).…”

“…The values from Shape [18] are 0.024 for the polyhedron around Cd1 and 0.067 for the polyhedron around Cd2, which . [17,12] The CÀ C distances are in the expected range of carbon triple bonds. [19] For further geometric parameters please check Table 1 and the supporting material.…”

“…Recently a compound of the composition Cs 2 Cd(C 2 H) 2 (C 2 ) has been presented. This compound is synthesized from caesium tetraethinylocadmate [12] via two different routes -on the one hand by heating to 200 °C in an argon atmosphere and on the other hand under ammonothermal conditions. [13] The starting material Cs 2 Cd(C 2 H) 4 and its analogues [12,14,15,16] are well-known and contain isolated [M II (C 2 H) 4 ] 2À tetrahedra.…”

Cs2Zn(CN)4: a first example of a non-cyano spinel of composition A2M(CN)4 with A=alkali metal and M=group 12 metal

“…T = 398 K losing its ferroelastic properties [14]. Ternary cyanides with the general composition A 2 M(CN) 4 with A = alkali metal and M = Zn, Cd are interesting starting materials for the respective acetylides A 2 M(C 2 H) 4 [15]. In our own studies, we came across Cs 2 Zn(CN) 4 , whose diffraction pattern did not show any similarity with a cubic or distorted rhombohedral spinel-type structure.…”