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NaRb 7 (Si 4– x Ge x ) 2 – Soluble Zintl Phases Containing Heteroatomic Tetrahedral [Si 4– x Ge x ] 4– Clusters
Author(s) -
Waibel Markus,
Pecher Oliver,
Mausolf Bernhard,
Haarmann Frank,
Fässler Thomas F.
Publication year - 2013
Publication title -
european journal of inorganic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.667
H-Index - 136
eISSN - 1099-0682
pISSN - 1434-1948
DOI - 10.1002/ejic.201300943
Subject(s) - chemistry , crystallography , zintl phase , nuclear magnetic resonance spectroscopy , dissolution , crystal structure , stereochemistry
Abstract The quaternary phases NaRb 7 (Si 4– x Ge x ) 2 ( x = 1–3) crystallize with an NaRb 7 Ge 8 ‐type structure and contain tetrahedral four‐atom clusters that consist of Si and Ge atoms. The quaternary phases possess larger cell volumes with increasing Ge amount. The formation of heteroatomic [Si 4– x Ge x ] 4– clusters is indicated by chemically different Si environments, which were analyzed by means of solid‐state 29 Si MAS (magic‐angle spinning) NMR spectroscopy of a 29 Si‐enriched NaRb 7 (Si 4– x Ge x ) 2 sample with x = 0.5 as well as quantum chemical calculations of the NMR coupling parameters. NaRb 7 (Si 4– x Ge x ) 2 represents another rare example of a phase with exclusively tetrahedral clusters that readily dissolves in liquid ammonia. The nature of the heteroatomic clusters was further investigated by dissolution of NaRb 7 (Si 4– x Ge x ) 2 with x = 2 in liquid ammonia. In the presence of MesCu (Mes = mesityl) and 18‐crown‐6 as a sequestering agent, crystals with the composition [Rb(18‐crown‐6)] 2 Rb 2 [(MesCu) 2 (Si 4– x Ge x )](NH 3 ) 11 were isolated with x = 2.2(1). [(MesCu) 2 (Si 4– x Ge x )] 4– represents another isomer of a MesCu‐stabilized tetrahedral anion and supports the observation that Zintl phases, which contain solely tetrahedranide subunits, represent a new class of soluble Zintl phases.