New Dihydrogenhypodiphosphates of Alkaline‐Earth Metals: Preparation, Crystal Structure, Vibrational Spectrum and Thermal Behavior of AE[H₂P₂O₆] ⋅ n H₂O (AE=Ca, Sr and n=1.5, 2)

Abstract

Dedicated to Professor Thomas M. Klapötke on the Occasion of his 60th Birthday Two new alkaline-earth metal dihydrogenhypodiphosphates, AE[H 2 P 2 O 6 ] • n H 2 O (AE = Ca, Sr and n = 1.5, 2) have been prepared and structurally characterized by single crystal X-ray diffraction. Calciumdihydrogenhypodiphosphate sesquihydrate, Ca[H 2 P 2 O 6 ] • 1.5 H 2 O (1) (lattice parameters:in the orthorhombic space group Pbcn. The crystal structure of compound 1 consists of chains of edge-and face-sharing of [CaO 6 ] and [CaO 8 ] polyhedra linked by dihydrogenhypodiphosphate(IV) anions to form a three-dimensional network. The structure of 2 consists of alternating layers of chains of edge-sharing [SrO 8 ] polyhedra and respective anionic units. The different water-content compositions result from the corresponding alkaline-earth metal coordination polyedra and by the preferred number of water molecules in their coordination sphere, respectively. The IR/Raman spectra of the title compounds have been recorded and interpreted, especially with respect to the [H 2 P 2 O 6 ] 2À group. The phase purity of 2 was verified by powder diffraction measurements.

Crystal engineering and structural diversity of 2-aminopyridinium hypodiphosphates obtained by crystallization and dehydration

“…Moreover, the tendency of hypodiphosphates to form networks stabilized by strong O–H⋯O hydrogen bonds, composed exclusively of hypodiphosphate anions and/or acid molecules, has been clearly indicated. 20–24 Hypodiphosphate substructures are stabilized by the formation of one, two or three hydrogen bond bridges between anions or acid molecules. In most of the known crystals of organic hypodiphosphates, two hydrogen bonds link adjacent anions giving rise to motifs as shown in Fig.…”