Crystal structure, infrared and Raman spectra of copper trihydrogenperiodate monohydrate, CuH3IO6 center dot H2O

The hitherto unknown compound CuH3IO6 . H2O was studied by X-ray, IR- and R aman spectroscopic methods. The crystal structure was determined by X-ray s ingle-crystal studies (space group P2(1)2(1)2(1), Z=4, a=532.60(10), b= 624 .00(10), c=1570.8(3) pm, R1=1.85%, 1559 unique reflections (I > 2 sigma (I) )). Isolated, meridionally configurated H3IO62- ions are coordinated to the copper ions forming double-ropes in [100]. These ropes are connected in [0 10] and [001] by hydrogen bonds. The copper ions possess a square pyramidal coordination with the hydrate H2O on top. The infrared and Raman spectra a s well as group theoretical treatment are presented and discussed with resp ect to the strength of the hydrogen bonds and the co-ordination of the CuO5 (+1) polyhedra and the H3IO62- ions at the C-1 lattice sites. The hydrogen bonds of the H2O molecules and H3IO62- ions (HO-H . . . O-IO5H3 and H2IO5O- H . . . O-IO5H3) greatly differ in strength, as shown from both the respect ive O . . . O distances: 282.6 and 298.6 pm (H2O), and 258.8, 259.7, and 27 0.9 pm (H3IO62-) and the OD stretching modes of isotopically dilute samples : 2498 and 2564 cm(-1) (90 K) (HDO), and 1786, 2024, and 2188 cm(-1) (H2DIO 62-). The IO stretching modes of the H3IO62- ions (696-758 cm(-1) and 555-6 58 cm(-1), 295 K) display the different strength of the respective I-O and I-O(H) bonds (r(I-O): 181.1-158.3 pm and 189.2-194.5 pm).