Abstract
Chemical preparation, single-crystal X-ray structure, and infrared and polarized Raman spectra of a new cadmium dibarium bis(monohydrogen monophosphate) bis(dihydrogen monophosphate) are presented. The atomic arrangement consists of anionic layers formed by HPO2−4 and H2PO−4 groups connected to each other through strong hydrogen bonds, resulting in a two-dimensional network. These sheets are held together by six oxygen-coordinated Cd2+ and nine oxygen-coordinated Ba2+ ions to build a three-dimensional framework. An assignment of lattice and internal vibrations in terms of symmetry species and approximate type of motion is given. A comparison with the vibrational fundamentals of the PO3−4 ion in the isostructural CaBa2(HPO4)2(H2PO4)2 (CaBa2) is also discussed. Band positions are found to be largely independent of the positive ion. Crystal data for CdBa2(HPO4)2(H2PO4)2 (CdBa2): M=773.08 g mol−1, monoclinic, space group P21/c (No. 14), a=5.434(4) Å, b=10.140(2) Å, c=12.298(2) Å, β=100.43(3)°, Z=2, R1/wR2=0.024/0.066 [1858 observed reflections with I>6σ(I)].