6-Fold-Coordinated Beryllium in Calcite-Type Be[CO3].

The anhydrous beryllium carbonate Be[CO3] with calcite-type crystal structure was obtained by a reaction of BeO with CO2 in a laser-heated diamond anvil cell at pressures between 30 GPa and 80 GPa and elevated temperatures. Its calcite-type crystal structure (R3̅c with Z = 6) is characterized by 6-fold-coordinated beryllium atoms forming [BeO6] octahedra and by trigonal-planar [CO3]2- groups. The crystal structure was determined by synchrotron-based single-crystal X-ray diffraction and confirmed by density-functional-theory-based calculations in combination with experimental Raman spectroscopy. Calcite-type Be[CO3] was synthesized at significantly lower pressures than the other very few compounds hosting 6-fold-coordinated beryllium, and it is the first beryllium carbonate with this coordination.