The synthesis of ternary acetylides with tellurium: Li₂TeC₂ and Na₂TeC₂

Abstract

Novel ternary acetylides Li2TeC2 and Na2TeC2 were synthesized via the robust direct reaction of tellurium powder and mono- or bialkali acetylides in liquid ammonia.

AISeC2H (AI=K, Rb, Cs): Crystalline Compounds with the Elusive −Se‐C≡C‐H Anion

“…In Figure S9 (Supporting Information) the IR spectra of CsSeC 2 Hand potential Cs 2 Se 2 (C 2 )are compared. [19] In our investigations we were able to reproduce the XRPD patterns published in this work ( Figure S10d), Supporting Information). Thef ormer was expected due to the Table 2: Cubic lattice parameters a and unit cell volumes V obtained for compounds with the potential composition A I 2 X 2 (C 2 )w ith A I = Na-Cs and X = Se, Te.…”

“…Thef ormer was expected due to the Table 2: Cubic lattice parameters a and unit cell volumes V obtained for compounds with the potential composition A I 2 X 2 (C 2 )w ith A I = Na-Cs and X = Se, Te. Thus,w ed on ot believe in ac ompound Na 2 TeC 2 with linear ···TeÀCCÀTe ··· chains as postulated by NØmeth et al [19] Instead we think that ac ompound with the composition Na 2 Te 2 (C 2 )w ith as till unknown crystal structure is formed as for the respective selenium compounds.S imilar results were obtained for A I = K, Rb (Table 2). release of C 2 H 2 and thus hydrogen from the compound.…”

“…[15] Very recently,t hese compounds have attracted some attention, as based on DFT calculations it was concluded that they should exhibit an anomalous anisotropy of workfunction values [16] making them interesting candidates for possible applications as photocathodes [17] and novel intercalation electrode materials for batteries. [19] However, as the quality of the XRPD patterns used for the solution and refinement of these crystal structures was only of very modest quality and as some of the interatomic distances resulting from these refinements led to quite unexpected values,w e decided to shed some light upon the reactivity of alkali metal acetylides A I C 2 Hand A I 2 C 2 with group 16 elements (S,Se, Te) in liquid ammonia. [16] Although the assumption of Te 0 with al inear coordination is not in agreement with the expected coordination geometry,itwas the same group that claimed in arecent work the successful synthesis and structural elucidation of Li 2 Te C 2 crystallizing in the Na 2 PdC 2 structure type as well as Na 2 Te C 2 ,crystallizing in adifferent structure,but also exhibiting linear ···Te-C C-Te··· chains.…”

“…[16] Although the assumption of Te 0 with al inear coordination is not in agreement with the expected coordination geometry,itwas the same group that claimed in arecent work the successful synthesis and structural elucidation of Li 2 Te C 2 crystallizing in the Na 2 PdC 2 structure type as well as Na 2 Te C 2 ,crystallizing in adifferent structure,but also exhibiting linear ···Te-C C-Te··· chains. [19] However, as the quality of the XRPD patterns used for the solution and refinement of these crystal structures was only of very modest quality and as some of the interatomic distances resulting from these refinements led to quite unexpected values,w e decided to shed some light upon the reactivity of alkali metal acetylides A I C 2 Hand A I 2 C 2 with group 16 elements (S,Se, Te) in liquid ammonia. In the following we will describe our work using grey selenium as as tarting material.…”

“…In first experiments we followed the synthesis procedure described for Na 2 Te C 2 [19] and reacted NaC 2 Hw ith selenium powder (grey allotrope) in a2 :1 ratio in liquid ammonia. Immediately,weobserved the formation of an orange-colored suspension, from which ay ellow-brownish precipitate (Figure S1, Supporting Information) was obtained after evaporation of the ammonia.…”