Ternäre Alkalimetall-Übergangsmetall-Acetylide der Zusammensetzung A2MC2 mit A = Rb, Cs und M = Pd, Pt

Abstract

Frau Professor Baudler zu ihrem 80. Geburtstag gewidmet Inhaltsu È bersicht. Durch Umsetzung von Rubidium-und Caesiumacetylid mit Palladium-bzw. Platinpulver in abgeschmolzenen Glasampullen konnten bei 653 K terna È re Acetylide der Zusammensetzung A 2 MC 2 (A = Rb, Cs; M = Pd, Pt) erhalten werden. Ihre Kristallstrukturen wurden auf Grundlage von Ro È ntgenpulveruntersuchungen gelo È st und verfeinert (Na 2 PdC 2 -Typ, P 3 m1, Z = 1). Die Strukturen sind durch 1 1 [M(C 2 ) 2/2 2± ]-Ketten charakterisiert, die von den Alkalimetallionen separiert werden. Ramanspektroskopische Untersuchungen ergaben Wellenzahlen zwischen 1833 und 1842 cm ±1 fu È r die C±C-Streckschwingungen, die sehr gut mit den Frequenzen in den analogen Natrium-und Kaliumverbindungen u È bereinstimmen. Ternary Alkali Metal Transition Metal Acetylides A 2 MC 2 with A = Rb, Cs, and M = Pd, PtAbstract. By the reaction of Rb 2 C 2 and Cs 2 C 2 with palladium or platinum powder in sealed glass ampoules at 653 K ternary acetylides A 2 MC 2 (A = Rb, Cs; M = Pd, Pt) were obtained. Their crystal structures were solved and refined by means of X-ray powder investigations (Na 2 PdC 2 structure type, P 3 m1, Z = 1). The crystal structures are characterised by 1 1 [M(C 2 ) 2/2 2± ] chains separated by the alkali metals. Raman spectroscopic investigations revealed wave numbers of the C±C stretching vibrations between 1833 and 1842 cm ±1 , which are in good agreement with the results of the analogous sodium and potassium compounds.

Ternary Alkali Metal Transition Metal Acetylides

“…This, of course complicated the structural solution from powder diffraction data for a long time. But with the knowledge of the crystal structures of Rb 2 C 2 and Cs 2 C 2 the synthesis of A 2 M 0 C 2 (A = Rb, Cs; M 0 = Pd, Pt) and the solution and refinement of their crystal structures were straightforward [17].…”

“…These interactions are probably a consequence of short Na-Pd distances (Na-Pd: 296.8 pm) in the crystal structure of Na 2 PdC 2 , which are among the shortest Na-Pd distances found in the ICSD database. For Cs 2 PdC 2 [17], which is also a semiconductor, Cs-Pd distances of 355.6 pm have been determined, which are also among the shortest Cs-Pd distances found in this database. Compared to this the shortest Cs-Ag distances in CsAgC 2 (427.9 pm) and Na-Ag distances in NaAgC 2 (375.4 pm) [28] are not remarkable and Cs-Ag/Na-Ag interactions can be excluded.…”

Ternary Transition Metal Acetylides AI2M0C2 (AI = K, Rb; M0 = Pd, Pt): Neutron Diffraction Studies and Electronic Properties

“…In these investigations Na 2 PdC 2 and Na 2 PtC 2 were always obtained as black powders. In subsequent work also the analogous potassium [3], rubidium and cesium compounds [4] were prepared, again as black powders.…”

NaCu5(C2)3: The First Alkali Metal Transition Metal Acetylide with a Three‐dimensional Framework Structure

“…Thus, this difference in the IR spectra of Cu 2 C 2 and NaCu 5 (C 2 ) 3 does not exclude a possible structural similarity between both compounds, but as there are also big differences in other ranges of the IR spectra, it is very unlikely that NaCu 5 (C 2 ) 3 represents are crystalline model compound for the unknown structure of Cu 2 C 2 . More similarities are found in the spectra of NaCu 5 (C 2 ) 3 and phenylethynylcopper(I) ( [18,19], see Table 3). For the later only a vague structural model has been given [27], but the general structural features are similar to those found in NaCu 5 (C 2 ) 3 , i.e.…”

“…sections of these channels. The vibrational spectra of NaCu 5 (C 2 ) 3 show some similarities with the spectra of phenylethynylcopper(I), but they are different to those of Cu 2 C 2 . Therefore NaCu 5 (C 2 ) 3 does probably not represent a crystalline model compound for the unknown structure of amorphous Cu 2 C 2 .…”