Angewandte Chemie International Edition
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Back Cover: Detection of the Elusive Highly Charged Zintl Ions Si44− and Sn44− in Liquid Ammonia by NMR Spectroscopy (Angew. Chem. Int. Ed. 16/2013)
Tetrahedral cages of tin and silicon are well-established in solid compounds of these elements with electropositive metals, but for a long time, doubt remained as to whether the classic Zintl formulation of a complete charge transfer would lead to stable anions if extracted by solvents. In their Communication on page 4483 ff., N. Korber, R. M. Gschwind, and co-workers present the detection by NMR spectroscopy of Sn44− and Si44− dissolved in liquid ammonia.