Phase formation in the HfO(NO3)2-H3PO4-CsF(HF)-H2O system

The phase formation in the system HfO(NO₃)₂-H₃PO₄-CsF(HF)-H₂O was studied along the sections at the molar ratios PO ₄ ^3? /Hf = 0.5, 1.5, and 2.0 and RbF:Hf = 1?C5, and also in the presence of HF at CsF: Hf = 1. The initial solutions contained 2?C24 wt % HfO₂. The synthesis was performed at room temperature. The following substances were isolated: crystalline cesium fluorophosphate hafnates CsHf₂F₆PO₄ · 4H₂O, CsHfF₂PO₄ · 0.5H₂O, and CsH₂Hf₂F₂(PO₄)₃ · 2H₂O; X-ray amorphous cesium fluorophosphate hafnate of the average composition Cs₂Hf₃O_1.5F₅(PO₄)₂ · 5H₂O; and X-ray amorphous cesium fluorophosphate nitrate hafnate Cs₅H₄Hf₃F₇(PO₄)_3.66(NO₃)₃ · 5H₂O. The compositions of the amorphous phases should be refined. Cesium fluorophosphate hafnates were obtained for the first time. The compounds were studied by crystal-optical, elemental, X-ray diffraction, IR spectroscopic, and electron microscopic analyses.     

Phase formation along sections of the HfO(NO3)2-H3PO4-RbF-H2O system

The phase formation in the system HfO(NO₃)₂-H₃PO₄-RbF-H₂O was studied along the sections at the molar ratios PO ₄ ^3? /Hf = 0.5, 1.0, 1.5, 2.0, and 3.0 and RbF: Hf = 1?5. The initial solutions contained 2–10 wt % HfO₂. The synthesis was performed at room temperature. The following substances were obtained for the first time: crystalline fluorophosphatehafnate RbHfF₂PO₄ · 0.5H₂O, crystalline triple salt HfF₄ · Rb(PO₄)_0.33 · RbNO₃, crystalline solvate Rb₃Hf₃(PO₄)₅ · 3HF, and amorphous fluorophosphate Hf₃O₂F₂(PO₄)₂ · 8H₂O (formula is conditional). The compounds were studied by crystal-optical, elemental, X-ray diffraction, thermogravimetric, IR spectroscopic, and electron microscopic analyses.     

Phase formation in the ZrO(NO3)2-H3PO4-CsF(HF)-H2O system

The phase formation in the system ZrO(NO₃)₂-H₃PO₄-CsF(HF)-H₂O was studied at the molar ratio CsF/Zr = 1 along the sections PO ₄ ^3? /Zr = 0.5 and 1.5 at a ZrO₂ concentration in the initial solution of 2?C14 wt %. The following compounds were isolated: Cs₅Zr₄F₂₁ · 3H₂O, CsZr₂(PO₄)₃ · 2HF · 2H₂O, CsZrF₂PO₄ · H₂O, CsZr₂F₆PO₄ · 4H₂O (for the first time), CsHZrF₃PO₄ (for the first time), Cs_0.70ZrF(PO₄)_1.23 · nH₂O, and CsHZr₂F₂(P_O4)_2.66 · nH₂O. The compositions of CsZrF₂PO₄ · H₂O, Cs_0.70ZrF(PO₄)_1.23 · nH₂O, and CsHZr₂F₂(PO₄)_2.66 · nH₂O are conditional. All the compounds were characterized by crystal-optical, X-ray powder diffraction, thermal analyses, and IR spectroscopy. The formula CsHZrF₃PO₄ was established by energy-dispersive analysis with a LEO-1450 scanning electron microscope and an MS-46 CAMECA X-ray microanalyzer.     

Zur Existenz der Verbindung K2TiOF4: Pyrohydrolytischer Abbau von K2TiF6 und thermochemisches Verhalten von K2Ti(O2)F4 · H2O

On the Existence of the Compound K₂TiOF₄: Pyrohydrolytic Degradation of K₂TiF₆ and Thermochemical Behaviour of K₂Ti(O₂)F₄ · H₂O In an attempt to prepare K₂TiOF₄ we used the following three ways; solid-state reaction of K₂TiF₆, TiO₂, and KF, pyrohydrolysis of K₂TiF₆ at 450 and 550°C, and thermal decomposition of K₂Ti(O₂)F₄ · H₂O. In each case the reaction products were mixtures of several compounds, always containing the kryolith-phase K_2+xTiO_xF_6?x and TiO₂. At 130°C K₂Ti(O₂)F₄ · H₂O forms K₂Ti(O₂)F₄ by loss of H₂O, and at 230°C the peroxogroup decomposes, yielding K₂TiOF₄ as main product. K₂TiOF₄ crystallizes tetragonally with the following lattice parameters: a = 769.7(1) and c = 1153.9(2)pm. The i.r. spectrum shows an absorption band at 810 cm^?1, pointing to infinite chains of ? Ti? O? Ti? O? .     

Ein- und zweikernige Fluorokomplexe des Titan(III), Chrom(III) und Eisen(III) Darstellung und Struktur von (NMe4)(Ti(H2O)4F2)TiF6 · H2O, (NMe4)3Cr2F9 und (NMe4)3Fe2F9

Mono- and Dinuclear Fluoro Complexes of Titanium (III), Chromium (III), and Iron(III). Syntheses and Structures of (NMe₄) (Ti(H₂O)₄F₂)TiF₆ · H₂O, (NMe₄)₃Cr₂F₉, and (NMe₄)₃Fe₂F₉ The title compounds have been prepared by reaction of MCl₃ (M = Ti, Cr, Fe) with NMe₄F in dimethylformamide. (NMe₄)₃Cr₂F₉ and (NMe₄)₃Fe₂F₉ contain the face-sharing biocathedral M₂F₉^3? unit. The M…M distances are 277.1(1) and 289.8(3) pm in (NMe₄)₃Cr₂F₉ and (NMe₄)Fe₂F₉, respectively. (NMe₄)(Ti(H₂O)₄F₂)TiF₆ · H₂O contains trans-Ti^III(H₂O)₄F₂⁺ cations and Ti^IVF₆^2? anions. Crystal data: (NMe₄)₃Cr₂F₉: hexagonal, space group P6₃/m, a = 804.1(3), c = 1857.5(4) pm, Z = 2, 529 reflections, R = 0.049; (NMe₄)₃Fe₂F₉: hexagonal, space group P6₃/m, a = 804.7(5), c = 1 861.6(5) pm, Z = 2, 635 reflections, R = 0,046; (NMe₄)(Ti(H₂O)₄F₂)TiF₆ · H₂O: orthorhombic, space group Pbca, a = 776.9(2), b = 1 616.3(3), c = 2 428.6(7) pm, Z = 8, 2 784 reflections, R = 0,056.     

Peroxofluorokomplexe der Übergangsmetalle. VIII. Kristallstruktur von K2Ti(O2)F4 · 1/2 H2O. Strukturchemischer Vergleich und spektroskopische Daten der Verbindungen K2Ti(O2)F4 · xH2O (mit x = 1, 1/2, 0)

Transition Metal Peroxofluoro Complexes. VIII. Crystal Structure of K₂Ti(O₂)F₄. · 1/2H₂O. Structural Comparison and Spectroscopic Data of the Compounds K₂Ti(O)₂F₄ · xH₂O (x = 1, 1/2, 0) The yellow hemihydrat K₂Ti(O₂)F₄ · 1/2 H₂O crystallizes monoclinic (space group C2/c, a = 1680.5(6), b = 653.2(1), c = 1224.3(4) pm, β = 115.8(1)°, Z = 8, Rw = 0.038 for 1113 independent reflections). It contains isolated, dinuclear, di(μ-fluoro)-bridged [Ti₂(O₂)₂F₈]^4? anions, as known by orange coloured K₂Ti(O₂)F₄ · H₂O [1]. They are arranged in layers which are parallel to the (100) plane, whereas they are linked by hydrogen bonds forming infinite chains in K₂Ti(O₂)F₄ · 1/2 H₂O. Anhydrous K₂Ti(O₂)F₄ - even yellow - crystallizes monoclinic with a = 828.9(2), b = 1107.6(2), c = 1303.9(3) pm, β = 92.29(2)°. I.r. and Raman spectra of all compounds are listed and interpreted. On the basis of the UV spectra the different colours of some titaniumperoxofluoro compounds are discussed in relation to the titanium-peroxid bonding.     

Peroxofluorokomplexe der Übergangsmetalle. IX. Kristallstruktur von Ba3[Ti(O2)F5]2 · 2 H2O

Transition Metal Peroxofluoro Complexes. IX. Crystal Structure of Ba₃[Ti(O₂)F₅]₂ · 2 H₂O The pale yellow hydrat Ba₃[Ti(O₂)F₅]₂ · 2 H₂O crystallizes tetragonal (space group P4₂/mbc, a = 1 248.5(3), c = 812.2(2) pm; Z = 4; R = 0.026 for 404 independent reflections). It contains isolated [Ti(O₂)F₅]^3? anions. Thermal decomposition leads directly to α-Ba₃Ti₂O₂F₁₀, which is isotypic to α-Ba₃Al₂F₁₂.     

Synthesis of rubidium fluorophosphatozirconates in the ZrO2-H3PO4-RbF-H2O system and their luminescent properties

Rubidium fluorophosphatozirconates (RFPZs) were synthesized along sections of the ZrO₂-H₃PO₄-RbF-H₂O system where PO ₄ ^3? /Zr = 1–2 (mol/mol) and RbF/Zr = 1–5 (mol/mol) and the initial solution contains 2–5 wt % ZrO₂. The following RFPZs have been isolated for the first time: RbZrF₂PO₄ · 0.5H₂O, Rb₃H₃Zr₃F₃(PO₄)₅, and RbZr₃F₄(PO₄)₃ · 1.5H₂O. Their formation fields were determined. The compounds were characterized using powder X-ray diffraction, crystal-optical analysis, chemical analysis, electron probe microanalysis, thermal analysis, and IR spectroscopy. Luminescent properties of the compounds were measured. All RFPZs are orthophosphates, have high thermal durability, and X-ray luminescence (XRL). Rb₃H₃Zr₃F₃(PO₄)₅ has the highest XRL intensity.     

Preparation,Single Crystal Structure Analysis,and Thermal Behaviour of the Acidic Mercury(I) Phosphate (Hg2)2(H2PO4)(PO4)

Yellowish single crystals of acidic mercury(I) phosphate (Hg₂)₂(H₂PO₄)(PO₄) were obtained at 200 °C under hydrothermal conditions in 32% HF from a starting complex of microcrystalline (Hg₂)₂P₂O₇. Refinement of single crystal data converged at a conventional residual R[F² > 2σ(F²)] = 3.8% (C2/c, Z = 8, a = 9.597(2) Å, b = 12.673(2) Å, c = 7.976(1) Å, β = 110.91(1)°, V = 906.2(2) ų, 1426 independent reflections > 2σ out of 4147 reflections, 66 variables). The crystal structure consists of Hg₂²⁺‐dumbbells and discrete phosphate groups H₂PO₄^– and PO₄^3–. The Hg₂²⁺ pairs are built of two crystallographically independent Hg atoms with a distance d(Hg1–Hg2) = 2.5240(6) Å. The oxygen coordination sphere around the mercury atoms is asymmetric with three O atoms for Hg1 and four O atoms for Hg2. The oxygen atoms belong to the different PO₄ tetrahedra, which in case of H₂PO₄‐groups are connected by hydrogen bonding. Upon heating over 230 °C, (Hg₂)₂(H₂PO₄)(PO₄) condenses to (Hg₂)₂P₂O₇, which in turn disproportionates at higher temperatures into Hg₂P₂O₇ and elemental mercury.     

Phase formation in the ZrO(NO3)2-NaF(HF)-H3PO4-H2O system at 20°C

Phase formation in the ZrO(NO₃)₂-NaF(HF)-H₃PO₄-H₂O system was studied at 20°C and 2.0–14.5 wt % ZrO₂ in the initial solution along sections with molar ratios PO ₄ ^3? /Zr = 0.5 and 1.5 and also in the presence of hydrogen fluoride at Na/Zr = 1 and PO ₄ ^3? /Zr = 0.5, 1.0, and 1.5. Crystalline zirconium hydrophosphate Zr(HPO₄)₂ · H₂O, fluorozirconates Na₅Zr₂F₁₃ and Na₇Zr₆F₃₁ · 12H₂O, fluorophosphatozirconates NaH₂Zr₃F₃(PO₄)₄ · 3H₂O and NaZr₂F₆(PO₄) · 4H₂O, and amorphous NaZrO_0.5F(PO₄) · 4H₂O (provisional composition) were separated at room temperature. NaH₂Zr₃F₃(PO₄)₄ · 3H₂O and NaZr₂F₆(PO₄) · 4H₂O were prepared for the first time and were studied by crystal-optical, elemental, and thermal analyses, X-ray powder diffraction, IR spectroscopy, scanning electron microscopy (SEM), and X-ray microanalysis. Na₇Hf₆F₃₁ · 12H₂O was found to exist in a mixture with the hydrophosphate.     

Phase formation in the ZrO(NO<Subscript>3</Subscript>)<Subscript>2</Subscript>-H<Subscript>3</Subscript>PO<Subscript>4</Subscript>-CsF-H<Subscript>2</Subscript>O system at low concentration of the phosphorus-containing component

The ZrO(NO₃)₂-H₃PO₄-CsF-H₂O system was studied at 20°C along the section at a molar ratio of PO₄³⁻/Zr = 0.5 (which is of the greatest interest in the context of phase formation) at ZrO₂ concentrations in the initial solutions of 2–14 wt % and molar ratios of CsF: Zr = 1−6. The following compounds were isolated for the first time: crystalline fluorophosphates CsZrF₂PO₄ · H₂O, amorphous oxofluorophosphate Cs₂Zr₃O₂F₄(PO₄)₂ · 3H₂O, and amorphous oxofluorophosphate nitrate CsZr₃O_1.25F₄(PO₄)₂(NO₃)_0.5 · 4.5H₂O. The compound Cs₃Zr₃O_1.5F₆(PO₄)₂ · 3H₂O was also isolated, which forms in a crystalline or glassy form, depending on conditions. The formation of the following new compounds was established: Cs₂Zr₃O_1.5F₅(PO₄)₂ · 2H₂O, Cs₂Zr₃F₂(PO₄)₄ · 4.5H₂O, and Zr₃O₄(PO₄)_1.33 · 6H₂O, which crystallize only in a mixture with known phases. All the compounds were studied by X-ray powder diffraction, crystal-optical, thermal, and IR spectroscopic analyses.     

Synthese,Kristallstruktur und Eigenschaften von Tetranatrium‐bis(trimetaphosphimato)cuprat(II)‐Decahydrat,Na4{Cu[(PO2NH)3]2} · 10 H2O

Synthesis, Crystal Structure, and Properties of Tetrasodium Bis(trimetaphosphimato)cuprate(II) Decahydrate, Na₄{Cu[(PO₂NH)₃]₂} · 10 H₂O Tetrasodium bis(trimetaphosphimato)cuprate(II) decahydrate, Na₄{Cu[(PO₂NH)₃]₂} · 10 H₂O, was obtained by the reaction of an aqueous solution of Na₃(PO₂NH)₃ · 4 H₂O with Cu(NO₃)₂ · 3 H₂O (molar ratio 2 : 1). The structure of Na₄{Cu[(PO₂NH)₃]₂} · 10 H₂O ( 1 ) was solved by single‐crystal X‐ray methods (P 1, a = 912.51(6), b = 932.14(6), c = 966.10(6) pm, α = 94.840(5), β = 108.652(6), γ = 118.588(6)°, Z = 1). The P₃N₃ rings of the trimetaphosphimate ions exhibit a slightly distorted sofa conformation. The conformation of the anions have been analysed using torsion angles, displacement asymmetry parameters, and puckering parameters. The trimetaphosphimate ions act as bidentate ligands of Cu²⁺. With additionally coordinated water molecules, anionic complexes {Cu[(PO₂NH)₃]₂ · 2 H₂O}^4– are formed. In the crystal these complexes are interconnected by N–H…O und O–H…O hydrogen bonds and they coordinate the Na⁺. Thus, a three‐dimensional network is formed.     

Ir spectroscopic and crystal morphology studies of the structure of alakli metal fluorophosphatozirconates (hafnates)

Potassium, rhubidium, and caesium fluorophosphatozirconates (hafnates) and oxo(hydroxo)fluorophosphatonitratometalates with PO ₄ ^3? /Zr molar ratios of 2.0, 1.5, 1.0, 0.66, 0.5, and 0.33 are synthesized for the first time. Most of them form either fine crystalline or X-ray amorphous particles. In order to characterize them IR spectroscopy and SEM are used. For the crystalline compounds the types of PO₄ groups and the character of bonds between fluorine and water are revealed. The occurrence of triple MeF₄·Rb(PO₄)_0.33·RbNO₃ (Me = Zr, Hf) salts and also M₃Me₃(PO₄)₅·3HF crystalline solvates is found. The layered habit of K₃Hf₃(PO₄)₅·3HF, RbHfF₂PO₄·0.5H₂O, Rb₃Hf₃(PO₄)₅·3HF, CsHfF₂PO₄·0.5H₂O, CsHf₂F₆PO₄·4H₂O, and CsH₂Hf₂F₂(PO₄)₃·2H₂O crystals gives grounds to suppose that the structure of these compounds is layered unlike the structure of triple MeF₄·Rb(PO₄)_0.33·RbNO₃ salts.     

Synthesis and thermal decomposition of neodymium(III) peroxotitanate to Nd<Subscript>2</Subscript>TiO<Subscript>5</Subscript>

Neodymium(III) peroxotitanate is used as a precursor for obtaining Nd₂TiO₅. The last one possesses numerous valuable electrophysical properties. TiCl₄, Nd(NO₃)₃·6H₂O and H₂O₂ in mol ratio 1:2:10 were used as starting materials. The reaction ambience was alkalized to pH = 9 with a solution of NH₃. The obtained neodymium(III) peroxotitanate and intermediate compounds of the isothermal heating were proved by the help of quantitative analysis and infrared spectroscopy (IRS). It has Nd₄[Ti₂(O₂)₄(OH)₁₂]·7H₂O composition. The absorption band observed in IRS at 831 cm^?1 relates to a triangular bonding of the peroxo group of Ti, at 1062 cm^?1—terminal groups Ti–OH and at 1491 and 1384 cm^?1—the bridging OH^?-groups Ti–O(H)–Ti. Nd₂TiO₅ was obtained by thermal decomposition of neodymium(III) peroxotitanate. The isothermal conditions for decomposition were determined on the base of differential thermal analysis, thermogravimetric and differential scanning calorimetry results in the temperature range of 20–1000 °C. The mechanism of thermal decomposition of Nd₄[Ti₂(O₂)₄(OH)₁₂]·7H₂O to Nd₂TiO₅ was studied. In the temperature range of 20–208 °C, a simultaneous decomposition of the peroxo groups by the separation of oxygen and hydrate water is conducted and Nd₄[Ti₂O₄(OH)₁₂] is obtained. From 208 to 390 °C, the terminal OH^?-groups are separated and Nd₄[Ti₂O₇(OH)₆] is formed. In the range of 390–824 °C, the bridging OH^?-groups are completely decomposed to Nd₂TiO₅. The optimal conditions for obtaining nanocrystalline Nd₂TiO₅ are 900 °C for 6 h and 20–80 nm.     

Preparation and Crystal Structure of Potassium Iron Hydrogen Phosphate,KFe3(HPO4)2(H2PO4)6 · 4 H2O

Single crystals of potassium iron hydrogen phosphate, KFe₃(HPO₄)₂(H₂PO₄)₆ · 4 H₂O, were prepared hydrothermally by heating a mixture of Fe₂O₃, H₃PO₄ and K₂CO₃ with a small amount of water. It crystallizes monoclinic, space group C2/c (N° 15 Int. Tab.) with Z = 4 and a = 1701(2), b = 960.4(5), c = 1750(1) pm, β = 90.88(7)°. The crystal structure was solved by using 1716 unique reflections F₀ > 4σ(F₀) with a final wR2 value of 0.126 (SHELXL-93). The main feature of the crystal structure are layers formed by PO₄-tetrahedra around the FeO₆-octahedra parallel to (001). K⁺ and H₂O molecules connect these layers. Effective Coordination Numbers (ECoN), Mean Fictive Ionic Radii (MEFIR), Charge Distribution (CHARDI) and the Madelung Part of Lattice Energy (MAPLE) are calculated for the title compound. The existence of hydrogen bonds is confirmed by these calculations.     

Titanium tetrafluoride complexation with phosphorylated ketone Ph<Subscript>2</Subscript>P(O)(CH<Subscript>2</Subscript>)<Subscript>2</Subscript>C(O)Me in CH<Subscript>2</Subscript>Cl<Subscript>2</Subscript>

The products resulting from the reaction of TiF₄ with Ph₂P(O)(CH₂)₂C(O)Me (L') in CH₂Cl₂ have been studied by ¹⁹F{¹H} and 31P{¹H} NMR spectroscopy. At a twofold excess of L', solution contains cis-TiF₄(L')2 (>90%), trans-TiF₄(L')₂, and fac-[TiF₃L₃']⁺, where L' is coordinated via the P=O group, as well as the dimer [(Ti₂F₇L'₂)₂]+, where L' is coordinated through the P=O and C=O groups. An equimolar solution contains dimeric and polynuclear complexes containing moieties with three terminal cis fluorine ions, while the other coordination sites are occupied by the P=O groups and F^– bridges. At a twofold excess of TiF₄, ligand L' coordinates via the P=O and C=O groups and behaves as a bridge along with F^– ions. Thermodynamic stability of the structures of the TiF₄L'₂ isomers and the structure of [(µ-F)(µ-L')₂(TiF₃)₂]⁺ has been calculated.     

Peroxofluorokomplexe der Übergangsmetalle. VII. Peroxofluorokryolithe A3Ti(O2)F5 (A = K,Na) und K2NaTi(O2)F5 Kristallstruktur von K3Ti(O2)F5

Transition Metal Peroxofluoro Complexes. VII. Peroxofluorokryolithes A₃Ti(O₂)F₅ (A = K, Na) and K₂NaTi(O₂)F₅. Crystal Structure of K₃Ti(O₂)F₅ Peroxofluorokryolithes A₃Ti(O₂)F₅ (A = K, Na) and K₂NaTi(O₂)F₅ were prepared at pH 4.5–6 by adding H₂O₂ and AOH/AF to solutions of TiO₂ in hydrofluoric acid or aqueous solutions of TiF₄. In the range of pH 3–4.5 exist phases of peroxofluoro-kryolithes with variations in stoichiometrie. A single crystall X-ray structure analysis of K₃Ti(O₂)F₅ (Fm3m, a = 883.6(1) pm) yielded a disordered kryolithstructure (R = 0.020, R_W = 0.017). Na₃Ti(O₂)F₅ was found to crystallize in two monoclinic low-temperature – and one cubic high-temperature modifications. K₂NaTi(O₂)F₅ crystallizes cubic (Fm3m) with a = 847.8(1) pm. Vibrational spectra have been measured and thermal behavior was studied by DTA/DTG and high-temperature guinier. At pH 9.5 K₃Ti(O₂)₂F₃ has been synthesized     

Thermal stability and X-ray luminescence properties of cesium fluorophosphatohafnates

The thermal stability of cesium fluorophosphatohafnates (crystalline CsHf₂F₂(HPO₄)₂PO₄ · 2H₂O, CsHfF₂PO₄ · 0.5H₂O, CsHf₂F₆PO₄ · 4H₂O and X-ray amorphous Cs₂Hf₃O_1.5F₅(PO₄)₂ · 5H₂O, Cs₅H₄Hf₃F₇(PO₄)_3.66(NO₃)₃ · 5H₂O) was determined. The weight ratios Cs⁺/Hf and PO ₄ ^3? /ZrHf in CsHf₂F₂(HPO₄)₂PO₄ · 2H₂O were confirmed by identifying the calcination production CsHf₂(PO₄)₃ (～1000°C). A new crystalline compound CsHf₂F(HPO₄)(PO₄)₂ was found by thermogravimetric and X-ray powder diffraction analysis during heating. A new method for hydrothermal synthesis of CsHf₂(PO₄)₃, which was different from the already known one, was proposed. It was ascertained that CsHf₂(PO₄)₃ possesses a significant X-ray luminescence; whereas in fluorophosphatehafnates show low luminescence intensity.     

Kristallstrukturen und thermisches Verhalten von Metalldihydrogenphosphat‐HF‐Addukten MH2PO4 · HF (M = K,Rb, Cs) mit Wasserstoffbrückenbindungen vom Typ F–H…O

Structures and Thermal Behaviour of Alkali Metal Dihydrogen Phosphate HF Adducts, MH₂PO₄ · HF (M = K, Rb, Cs), with Hydrogen Bonds of the F–H…O Type Three HF adducts of alkali metal dihydrogen phosphates, MH₂PO₄ · HF (M = K, Rb, Cs), have been isolated from fluoroacidic solutions of MH₂PO₄. KH₂PO₄ · HF crystallizes monoclinic: P2₁/c, a = 6,459(2), b = 7,572(2), c = 9,457(3) Å, β = 101,35(3)°, V = 453,5(3) ų, Z = 4. RbH₂PO₄ · HF and CsH₂PO₄ · HF are orthorhombic: Pna2₁, a = 9,055(3), b = 4,635(2), c = 11,908(4) Å, V = 499,8(3) ų, Z = 4, and Pbca, a = 7,859(3), b = 9,519(4), c = 14,744(5) Å, V = 1102,5(7) ų, Z = 8, respectively. The crystal structures of MH₂PO₄ · HF contain M⁺ cations, H₂PO₄^– anions and neutral HF molecules. The H₂PO₄^– anions are connected to layers by O–H…O hydrogen bonds (2,53–2,63 Å), whereas the HF molecules are attached to the layers via very short hydrogen bonds of the F‐H…O type (2,36–2,38 Å). The thermal decomposition of the adducts proceeds in three steps. The first step corresponds to the release of mainly HF and a smaller quantity of water. In the second and third steps, water evolution caused by condensation of dihydrogen phosphate is the dominating process whereas smaller amounts of HF are also released.     

ZrONO3)2-H3PO4-KF(HF)-H2O system at molar ratios of PO 43? /Zr = 0.5?1.6 as the basis for phase formation

The system ZrO(NO₃)₂-H₃PO₄-KF(HF)-H₂O was studied at ∼20°C along sections at molar ratios of PO₄³⁻ = 0.5, 1.0, and 1.6; KF: Zr = 1−5; and HF: Zr = 2−6. Phases in precipitates were identified by X-ray powder diffraction; IR spectroscopy; and crystal-optical, chemical, X-ray fluorescence and thermal analyses. The following crystalline phases were isolated: potassium fluorozirconates K₃ZrF₇, K₂ZrF₆, δ-KZrF₅, and KZrF₅ · H₂O; zirconium hydrophosphate Zr(HPO₄)₂ · 0.5H₂O; and potassium fluorophosphate zirconate K₃Zr₃F₃(HPO₄)₃(PO₄)₂. The following amorphous basic oxo(hydroxo)fluorohydrophosphate nitrates were isolated: K₄Zr₄O_2.5F₈(HPO₄)₂(NO₃)₃ · 6H₂O, K₂Zr₃O₃F₂(HPO₄)₂(NO₃)₂ · H₂O, and KZr₃O_1.5F₃(HPO₄)₂(NO₃)₃ · 2H₂O. Fields of solid phases were constructed, and the roles of anions and cations in the phase formation were considered.