Synthesis and Crystal Structure of Sb ₂ O ₂ [CO ₃ ] with Stereochemically Active Lone Electron Pairs at Elevated Pressures

The antimony oxide‐carbonate Sb 2 O 2 [CO 3 ] has been synthesized in a laser‐heated diamond anvil cell by a reaction between Sb 2 O 5 , H 2 O, and C (diamond). Its crystal structure was determined by synchrotron single‐crystal X‐ray diffraction and confirmed by density functional theory (DFT) calculations in combination with experimental Raman spectroscopy. The structure of Sb 2 O 2 [CO 3 ] is characterized by the presence of [CO 3 ] 2− ‐groups and hence belongs to the family of sp 2 ‐carbonates. The second building block of its crystal structure is interconnected “Sb 2 O 5 ‐units”, which form a Sb─O‐network within the b , c lattice plane. Our DFT calculations show the presence of stereochemically active lone electron pairs ≈0.7 Å away from the Sb 3+ ‐cations. The synthesis of Sb 2 O 2 [CO 3 ] is a significant enlargement of the crystal chemistry of carbonates, as (oxide‐)carbonates of antimony have not been described up to now, and it also allows us to study the influence of the presence of lone electron pairs on crystal structures at elevated pressures.