Three Crystal Structures, One Chemical Formula – Barium Dihydrogen‐hypodiphosphate(IV)‐dihydrate, BaH₂P₂O₆·2H₂O

Abstract

Three polymorphs of barium dihydrogen‐hypodiphosphate(IV)‐dihydrate, BaH2P2O6·2H2O (A, B and C), were obtained and structurally characterized by single‐crystal X‐ray diffraction. A crystallizes in the monoclinic space group P21/n (no. 14) with a = 7.459(1) Å, b = 8.066(1) Å, c = 12.460(2) Å, β = 91.27(1) ° and Z = 4. B crystallizes in the monoclinic space group C2/c (no. 15) with a = 11.049(8) Å, b = 6.486(3) Å, c = 10.956(6) Å, β = 106.89(5) ° and Z = 4. C crystallizes in the orthorhombic space group C2221 (no. 20) with a = 9.193(3) Å, b = 6.199(2) Å, c = 12.888(4) Å and Z = 4. Discrete [H2P2O6]2– units, barium cations and water molecules, held together by intermolecular hydrogen bonds of the type O–H···O, build up the structures of the three polymorphs. The phase purity of A and C was verified by powder diffraction measurements.

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)

“…(Ca1) 2+ is octahedrally coordinated by six monodentate [H 2 P 2 O 6 ] 2− anions with Ca1−O bond lengths ranging from 2.282(3) to 2.406(3) Å (Table 2), which are similar to those in other calcium salts reported previously [14] . (Ca2) 2+ is eightfold surrounded by two water molecules, two monodentate and two bidentate [H 2 P 2 O 6 ] 2− anions.…”

“…(Ca1 2), which are similar to those in other calcium salts reported previously. [14] [15] The PÀ P distances amount to 2.193(1) and 2.200(1) Å and are well within the expected ranges and thus comparable to those found for the respective hypodiphosphates. [15] The PÀ O bond lengths range from 1.492(3) to 1.587(3) Å ( [15] (Table 3 and Figure 4).…”

“…Ca 2 [P 2 O 6 ] ⋅ 2 H 2 O and Ba[H 2 P 2 O 6 ] ⋅ 2 H 2 O were first synthesized by Palmer in 1961 [11] . Recently, the magnesium, calcium and barium salts could be characterized by X‐ray diffraction [12–15] . The present work is a continuation of the structural studies of alkaline‐earth metal hypodiphosphates.…”

“…[11] Recently, the magnesium, calcium and barium salts could be characterized by X-ray diffraction. [12][13][14][15] The present work is a continuation of the structural studies of alkaline-earth metal hypodiphosphates.…”