Preparation, Crystal Structure and Vibrational Spectra of Ca 2 P 2 O 6 ·2H 2 O and [Ca(H 2 O) 3 (H 2 P 2 O 6 )]·0.5(C 12 H 24 O 6 )·H 2 O

The calcium salts Ca 2 P 2 O 6 · 2H 2 O ( 1 ) and [Ca(H 2 O) 3 (H 2 P 2 O 6 )] · 0.5(C 12 H 24 O 6 ) · H 2 O ( 2 ) were prepared and structurally characterized by single‐crystal X‐ray diffraction. Compound 1 crystallizes in the orthorhombic space group Pbca and compound 2 in the monoclinic space group P 2 1 / n . The crystal structure of compound 1 consists of chains of edge‐sharing [CaO 7 ] polyhedra linked by hypodiphosphate(IV) anions to form a three‐dimensional network. The crystal structure of compound 2 consists of alternated layers of crown ether and water molecules and respective ionic units. Within the layers of ionic units the Ca 2+ cations are octahedrally coordinated by three monodentate dihydrogenhypodiphosphate(IV) anions and three water molecules. The IR/Raman spectra of the title compounds were recorded and interpreted, especially with respect to the [P 2 O 6 ] 4– and [H 2 P 2 O 6 ] 2– groups. The phase purity of 2 was verified by powder diffraction measurements.