Synthesis and Crystal Structure of Anhydrous Di-iodyl Carbonate (IO 2 ) 2 [CO 3 ], Hosting I 5+ -Cations

High Resolution Image Download MS PowerPoint Slide The anhydrous di-iodyl carbonate (IO 2 ) 2 [CO 3 ] has been synthesized in a laser-heated diamond anvil cell at 30(2) GPa and 1600(200) K by a reaction of I 2 O 5 with CO 2 . Its monoclinic crystal structure ( C 2/ 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. (IO 2 ) 2 [CO 3 ]- C 2/ c belongs to the family of sp 2 -carbonates, and its crystal structure is characterized by the presence of nearly trigonal-planar [CO 3 ] 2– groups. In contrast to other iodide-containing carbonates, in this structure the iodine atoms are present as small and highly oxidized I 5+ -cations and not as large I – -anions. The I 5+ -cations are coordinated by seven oxygen atoms. The successful synthesis of (IO 2 ) 2 [CO 3 ]- C 2/ 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 sp 2 -carbonates hosting a positively charged halogen atom as the only cation can be synthesized.