Carbonate build up by metals: Whereas alkali metal carbonates are mostly insoluble in liquid ammonia, a carbonate analogue is formed by Bi and Sn by reaction of deeply colored solutions of polyanionc bismuthides and stannides in liquid ammonia and can be isolated as the potassium salt K₅SnBi₃⋅9 NH₃. In contrast to carbonate, the highly charged [BiSn₃]⁵⁻ ion decomposes readily in the presence of traces of water.

For article see: DOI:10.1002/anie.201709700 or DOI:10.1002/ange.201709700

K. Mayer, J. V. Dums, W. Klein, T. F. Fässler [SnBi₃]^5– − A Carbonate Analogue Comprising Exclusively Metal Atoms

Angew. Chem. Int. Ed. 56 (2017) 15159–15163