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NaSeC 2 H: A Crystalline Compound with Disordered – SeC 2 H Anions
Author(s) -
Hetzert Marc,
Tobeck Christian,
Ruschewitz Uwe
Publication year - 2020
Publication title -
zeitschrift für anorganische und allgemeine chemie
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.354
H-Index - 66
eISSN - 1521-3749
pISSN - 0044-2313
DOI - 10.1002/zaac.202000131
Subject(s) - crystallography , powder diffraction , thermal decomposition , chemistry , ion , formula unit , synchrotron , x ray crystallography , decomposition , crystal structure , liquid ammonia , analytical chemistry (journal) , ammonia , materials science , diffraction , physics , organic chemistry , chromatography , nuclear physics , optics
By reaction of NaC 2 H with elemental selenium (grey or red) in liquid ammonia a crystalline brownish powder of NaSeC 2 H was obtained. The existence of the new – SeC 2 H anion – recently discovered in A I SeC 2 H (A I = K, Rb, Cs) – was confirmed by IR spectra showing the expected C≡C, C–H, and C–Se vibrations. A synchrotron powder diffraction pattern (SNBL, ESRF/Grenoble) was indexed in a cubic unit cell with a = 7.044 Å. Analysis of the data led to a pyrite‐type structure ( Pa 3 , Z = 4) with a static orientational disorder of the – SeC 2 H anions over two positions. No phase transition was observed upon cooling to 100 K, where essentially the same structure was obtained with a = 6.989 Å. Upon heating, NaSeC 2 H releases C 2 H 2 as revealed by thermal analysis (DSC/TGA) resulting in potential Na 2 Se 2 C 2 crystallizing in a small cubic unit cell with a ≈ 3.899 Å similar to findings on the decomposition of the other A I SeC 2 H compounds.