Sr[C 2 O 5 ] is an Inorganic Pyrocarbonate Salt with [C 2 O 5 ] 2- Complex Anions.

The synthesis of a novel type of carbonate, namely of the inorganic pyrocarbonate salt Sr[C 2 O 5 ], which contains isolated [C 2 O 5 ] 2- -groups, significantly extends the crystal chemistry of inorganic carbonates beyond the established sp 2 - and sp 3 -carbonates. We synthesized Sr[C 2 O 5 ] in a laser-heated diamond anvil cell by reacting Sr[CO 3 ] with CO 2 . By single crystal synchrotron diffraction, Raman spectroscopy, and density functional theory (DFT) calculations, we show that it is a pyrocarbonate salt. Sr[C 2 O 5 ] is the first member of a novel family of inorganic carbonates. We predict, based on DFT calculations, that further inorganic pyrocarbonates can be obtained and that these will be relevant to geoscience and may provide a better understanding of reactions converting CO 2 into useful inorganic compounds.