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Synthesis and Crystal Structure of Anhydrous Di-iodyl Carbonate (IO2)2[CO3], Hosting I5+-Cations
Dominik Spahr1, Lkhamsuren Bayarjargal1, Lukas Brüning2
1Goethe University Frankfurt, Institute of Geosciences, Altenhöferallee 1, 60438 Frankfurt, Germany.
Abstract:
The anhydrous di-iodyl carbonate (IO2)2[CO3] has been synthesized in a laser-heated diamond anvil cell at 30(2) GPa and 1600(200) K by a reaction of I2O5 with CO2. Its monoclinic crystal structure (C2/c with Z = 4) was determined from synchrotron single crystal X-ray diffraction data. The experimental structural model was confirmed by density functional theory based calculations in combination with experimental Raman spectroscopy. (IO2)2[CO3]-C2/c belongs to the family of sp2-carbonates, and its crystal structure is characterized by the presence of nearly trigonal-planar [CO3]2- groups. In contrast to other iodide-containing carbonates, in this structure the iodine atoms are present as small and highly oxidized I5+-cations and not as large I--anions. The I5+-cations are coordinated by seven oxygen atoms. The successful synthesis of (IO2)2[CO3]-C2/c represents a significant enlargement of the crystal chemistry of carbonates, as this chemically simple carbonate demonstrates that anhydrous carbonates with highly charged cations can be formed and that sp2-carbonates hosting a positively charged halogen atom as the only cation can be synthesized.
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