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

The anhydrous beryllium carbonate Be[CO] with calcite-type crystal structure was obtained by a reaction of BeO with CO in a laser-heated diamond anvil cell at pressures between 30 GPa and 80 GPa and elevated temperatures. Its calcite-type crystal structure (3̅ with = 6) is characterized by 6-fold-coordinated beryllium atoms forming [BeO] octahedra and by trigonal-planar [CO] 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[CO] 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.