6‑Fold-Coordinated\nBeryllium in Calcite-Type\nBe[CO<sub>3</sub>]

The anhydrous beryllium carbonate Be[CO<sub>3</sub>]\nwith calcite-type\ncrystal structure was obtained by a reaction of BeO with CO<sub>2</sub> in a laser-heated diamond anvil cell at pressures between 30 GPa\nand 80 GPa and elevated temperatures. Its calcite-type crystal structure\n(<i>R</i>3̅<i>c</i> with <i>Z</i> = 6) is characterized by 6-fold-coordinated beryllium atoms forming\n[BeO<sub>6</sub>] octahedra and by trigonal-planar [CO<sub>3</sub>]<sup>2–</sup> groups. The crystal structure was determined\nby synchrotron-based single-crystal X-ray diffraction and confirmed\nby density-functional-theory-based calculations in combination with\nexperimental Raman spectroscopy. Calcite-type Be[CO<sub>3</sub>] was\nsynthesized at significantly lower pressures than the other very few\ncompounds hosting 6-fold-coordinated beryllium, and it is the first\nberyllium carbonate with this coordination.