Vibrational spectra of the peroxochromates (NH₄)₃[Cr(O₂)₄], K₃[Cr(O₂)₄] and Rb₃[Cr(O₂)₄]

Abstract

Abstract The compounds (NH 4 ) 3 [Cr(O 2 ) 4 ], K 3 [Cr(O 2 ) 4 ] and Rb 3 [Cr(O 2 ) 4 ] were prepared and investigated by x‐ray powder methods and Raman and IR spectroscopy. From the powder x‐ray diffraction data it is shown that both (NH 4 ) 3 [Cr(O 2 ) 4 ] and Rb 3 [Cr(O 2 ) 4 ] are isotypic to the K 3 [Cr(O 2 ) 4 ] type (space group I 4 2 m , No. 121). The infrared and Raman spectra (recorded on powdered samples) are discussed with respect to the internal vibrations of the peroxo group and the dodecahedral [Cr(O 2 ) 4 ] 3− ion. The stretching vibrations of the O 2 2− groups are found at 838 (Raman) and 813 cm −1 (IR). The preparation of the corresponding cesium compound did not succeed as the samples exploded. Copyright © 2003 John Wiley & Sons, Ltd.