Synthesis and Structure of Pb[CO]: An Inorganic Pyrocarbonate Salt.

We have synthesized Pb[CO], an inorganic pyrocarbonate salt, in a laser-heated diamond anvil cell (LH-DAC) at 30 GPa by heating a Pb[CO] + CO mixture to ≈2000(200) K. Inorganic pyrocarbonates contain isolated [CO] groups without functional groups attached. The [CO] groups consist of two oxygen-sharing [CO] groups. Pb[CO] was characterized by synchrotron-based single-crystal structure refinement, Raman spectroscopy, and density functional theory calculations. Pb[CO] is isostructural to Sr[CO] and crystallizes in the monoclinic space group 2/ with = 4. The synthesis of Pb[CO] demonstrates that, just like in other carbonates, cation substitution is possible and that therefore inorganic pyrocarbonates are a novel family of carbonates, in addition to the established sp and sp carbonates.