Study of the Geometrical Structure and the Vibrational Spectra of P4O8, P4O6S2, and P4O6Se2

In the present work the bonding situation within the P₄O₆X₂ (X = O, S and Se) series is analysed by means of the geometrical structures and the IR spectra of those molecules. The experimental data are obtained from pure P₄O₈ and P₄O₆Se₂ crystals which could be synthesized for the first time. The theoretical geometrical structures were obtained by employing the Hartree-Fock method in combination with a basis set of double ζ quality plus polarization functions. Theoretical vibrational spectra calculated with the same method were refined by using the Scaled Quantum Mechanical method proposed by Pulay. Our study shows that the doubly substituted compounds behave very similar to the monosubstituted molecules, e. g. shifts of the vibrational frequencies result mainly from the differences in the bond strengths of the P = X units and the different masses of the substituents, while the bonding situation within the P₄O₆ frame remains nearly unchanged within this series.     

NaMn6(P2O7)2(P3O10) and KCd6(P2O7)2(P3O10)

The crystal structures of two new diphosphates, sodium hexamanganese bis­(diphosphate) triphosphate, NaMn₆(P₂O₇)₂(P₃O₁₀), and potassium hexacadmium bis­(diphosphate) triphosphate, KCd₆(P₂O₇)₂(P₃O₁₀), confirm the rigidity of the M₆(P₂O₇)₂(P₃O₁₀) matrix (M is Mn or Cd) and the relatively fixed dimensions of the tunnels extending in the a direction of the unit cell. The compounds are isomorphous; the P₂O₇^4? anion and the alkali metal cations lie on mirror planes. Bond‐valence analysis of the bonding details of the atoms found within the tunnels permits a prediction of the conductivity.     

Verbesserte Darstellung,Kristallzüchtung und Strukturanalyse von P4O6S2 und P4O6S3

Improved Syntheses, Crystal Growth, and Crystal Structure Determination of P₄O₆S₂ and P₄O₆S₃ Syntheses and single crystal growths of the title compounds are described. Both compounds crystallize in the space group P2₁/c (P₄O₆S₂: a = 11.293(4); b = 6.457(3); c = 11.588(4) Å; β = 90.29(2)°, 2 450 diffractometer data, R_w = 0.035/P₄O₆S₃: a = 15.611(5); b = 8,303(3); c = 9.697(4) Å; β = 127.12(2)°, 2 481 diffractometer data, R_w = 0.034). The structural data for the series P₄O₆S_n (n = 1 – 4) thus completed are compared to their oxide analogues P₄O₆O_n (n = 1 – 4). The changes in the geometry of the P₄O₆-cage in course of its successive oxidation are discussed.     

Preparation,Crystal Structure,Vibrational Spectra,and Thermal Behavior of Tl2H2P2O6 and Tl4P2O6

The new thallium(I) salts, Tl₂H₂P₂O₆ ( 1 ) and Tl₄P₂O₆ ( 2 ), were prepared and structurally characterized by single‐crystal X‐ray diffraction. Compound 1 crystallizes in the monoclinic space group P2₁/c and compound 2 in the orthorhombic space group Pbca. Both structures feature channels occupied by the lone electron pairs of Tl⁺ cations. Furthermore, those are built up by discrete [H₂P₂O₆]^2– for compound 1 and [P₂O₆]^4– units for 2 in staggered conformation for the P₂O₆ skeleton and the thallium cations. In Tl₂H₂P₂O₆ ( 1 ) the hydrogen atoms of the [H₂P₂O₆]^2– ion are in a “trans‐trans” conformation. The O ··· H–O hydrogen bonds between the [H₂P₂O₆]^2– groups consolidate the structure 1 into a three‐dimensional network. FT‐IR/FIR and FT‐Raman spectra of the crystalline title compounds were recorded and a complete assignment for the P₂O₆^4– modes is proposed. The phase purity of 1 was verified by powder diffraction measurements.     

Crystal Structure of a Tetrapoly-Dipolyphosphate: CaNb2O(P4O13)(P2O7)

Chemical preparation and crystal structure of CaNb₂O(P₄O₁₃)(P₂O₇) are described. The monoclinic unit cell has the following dimensions: a = 13.264(9), b = 10.577(8), c = 12.393(9) Å, β = 96.09(1)°. Space group is C2/m with Z = 4. The crystal structure has been solved by using 1204 unique reflexions with a final R value 0.049. The main outstanding feature of this compound rests on the coexistence in its atomic arrangement of two kinds of phosphate anions with different degrees of condensation: a tetrameric linear one: (P₄O₁₃)^6? and dimeric linear one: (P₂O₇)^4?. The atomic arrangement can be schematically described as a stacking of alternating rows of P₄O₁₃ and P₂O₇ groups, parallel to the ā axis. The P₄O₁₃ groups have a twofold symmetry while the P₂O₇ groups have a non usual mirror symmetry. One of the oxygen atoms does not belong to the phosphoric groups.     

Zur Darstellung von Phosphor(III,V)-oxiden: β-Phase P4O7–P4O8

The previously suggested end member P₄O₇ of the beta;hyphen;phase structure type of phosphorus (III,IV) oxides as well as the mixed-crystal β-phase P₄O₇–P₄O₈ have been prepared by oxidation of phosphorus(III) oxide dissolved in carbon tetrachloride. Without alteration of the crystal structure type, P₄O₇ and P₄O₈ molecules are mutually exchangeable in the phase range P₄O₇–P₄O_7,9, the density of such mixed crystals being strictly determined by the mean composition. The crystal structure of the β-phase is obviously fixed by the P₄O₇ molecular structure and not, as previously supposed, by that of the P₄O₈ molecules. The latter appear to occur in the pure state as, in general, amorphous substances.     

Synthese,Kristallstruktur und spektroskopische Charakterisierung von Tetraphosphorhexaoxiddiselenid P4O6Se2

Synthesis, Crystal Structure, and Spectroscopic Characterization of Tetraphosphorus Hexaoxide Diselenide P₄O₆Se₂ P₄O₆Se₂ has been prepared by photochemical selenation of P₄O₆ with red selenium in CS₂ in presence of catalytical amounts of iodine. Isolation and single crystal growth were performed by fractional crystallization and subsequent sublimation. The compound crystallizes in the monoclinic space group P2₁/c (Nr. 14) with a = 11.473(2); b = 6.536(1); c = 11.796(2) Å; β = 90.06(1)°; Z = 4; R₁ = 0.030; wR² = 0.073. Within the limits of experimental error, the P₄O₆Se₂ molecules exhibit C_2v symmetry in the crystal. Bond lengths and angles within the molecule as well as the arrangement of the molecules within the crystal are discussed; IR-, Raman-, and ³¹P solution NMR data are reported.     

The Ring Acid,H6P6O12 and Ring Acid,H4P4O10 and Their Salts

Abstract

The hydrated salts of the acid H₆P₆O₁₂, Rb₆P₆O·aq and M₃P₆O₁₂·aq (M = Ca, Sr, Ba), that have so far been unknown, have been prepared and studied by X-ray methods, thermal analysis and molecular spectroscopy. It has been found that the anion structure exhibits a chair form with the D_3d symmetry. All the salts are stable at laboratory temperature and are completely decomposed on prolonged heating to 80°C prior to complete dehydration. The newly prepared salts of the acid H₄P₄O₁₀ involve Cs₄P₄0₁₀·1.5 H₂O, Tl₄P₄O₁₀, M₂P₄O₁₀·x H₂O (M = Cu, Ni, Co; x = 10, 2, 6, respectively), Na₂MP₄O₁₀·x H₂O (M = Cu, Ni, Co; x = 8, 8, 4, respectively). They have been studied using X-ray methods, thermal analysis, molecular and reflectance spectra and the magnetic susceptibility. The dehydration of the salts starts at 30 to 40°C and ends by complete decomposition before the completion of dehydration at 150°C. The anion structure for the salt CS₄P₄O₁₀ in the crystalline state has a chair form with C₂ symmetry. However, the anion structure in aqueous solutions approaches a planar arrangement with the D_2h symmetry.     

Die Kristallstruktur des Bleicyclotetraphosphat-4-Hydrats,Pb2P4O12 · 4H2O

Crystal Structure of Lead Cyclotetraphosphate-4-Hydrate, Pb₂P₄O₁₂·4 H₂O Pb₂P₄O₁₂·4 H₂O is the starting product of a series of solid state reactions with the final product cyclooctaphosphate. Pb₂P₄O₁₂·4 H₂O crystallizes in the monoclinic space group P2₁/n, with a = 8.07 ± 0.02, b = 11.76 ± 0.03, c = 7.50 ± 0.02 Å and β = 108.2 ± 0.3°. The crystal structure has been solved by Patterson and Fourier methods and refined by least squares calculations to an R-index of 0.07. The structure consists of P₄0₁₂^4? ringanions, which are connected by Pb and hydrogen bonds. Lead is coordinated by eight oxygen atoms.     

High-Pressure Synthesis of Sc5P12N23O3 and Ti5P12N24O2 by Activation of the Binary Nitrides ScN and TiN with NH4F

Multinary transition metal nitrides and oxonitrides are a versatile and intriguing class of compounds. However, they have been investigated far less than pure oxides. The compounds Sc₅P₁₂N₂₃O₃ and Ti₅P₁₂N₂₄O₂ have now been synthesized from the binary nitrides ScN and TiN, respectively, by following a high-pressure high-temperature approach at 8 GPa and 1400 °C. NH₄F acts as a mineralizing agent that supports product formation and crystallization. The starting materials ScN and TiN are seemingly an uncommon choice because of their chemical inertness but, nevertheless, react under these conditions. Sc₅P₁₂N₂₃O₃ and Ti₅P₁₂N₂₄O₂ crystallize isotypically with Ti₅B₁₂O₂₆, consisting of solely vertex-sharing P(O/N)₄ tetrahedra forming two independent interpenetrating diamond-like nets that host TM(O/N)₆ (TM=Sc, Ti) octahedra. Ti₅P₁₂N₂₄O₂ is a mixed-valence compound and shows ordering of Ti³⁺ and Ti⁴⁺ ions.     

Darstellung und Charakterisierung von P4O7S

Syntheses and Characterization of P₄O₇S P₄O₇S was synthesized for the first time and characterized by X-ray structure determination (single-crystal methods) and ³¹P-n.m.r. (solution and MAS-solid) (P1 ; a = 687.2(1); b = 718.2(1); c = 809.1(1) pm; α = 92.58(1)°; β = 104.43(1)°; γ = 94.82(2)°; 2 907 diffractometer data; R₁ = 0.030; wR² = 0.102). The different influences of terminally bound oxygen and sulfur on the geometry of the P₄O₆ cage are discussed.     

Beiträge zum Koordinationsverhalten von Oxidionen in anorganischen Feststoffen. III [1] Mn2P2O7, Mn2P4O12 und Mn2Si(P2O7)2 — Kristallzüchtung,Strukturverfeinerungen und Elektronenspektren von Mangan(II)‐Phosphaten

Contributions on the Bonding Behaviour of Oxygen in Inorganic Solids. III [1] Mn₂P₂O₇, Mn₂P₄O₁₂ und Mn₂Si(P₂O₇)₂ — Crystal Growth, Structure Refinements and Electronic Spectra of Manganese(II) Phosphates By chemical vapour transport reactions in a temperature gradient single crystals of Mn₂P₂O₇ (1050 → 950 °C) and Mn₂P₄O₁₂ (850 → 750 °C) have been obtained using P/I mixtures as transport agent. Mn₂Si(P₂O₇)₂ was crystallized by isothermal heating (850 °C, 8d; NH₄Cl as mineralizer) of Mn₂P₄O₁₂ und SiO₂. In Mn₂Si(P₂O₇)₂ [C 2/c, a = 17.072(1)Å, b = 5.0450(4)Å, c = 12.3880(9)Å, β = 103.55(9)°, 1052 independent reflections, 97 variables, R1 = 0.023, wR2 = 0.061] the Mn²⁺ ions show compressed octahedral coordination (d¯_Mn—O = 2.19Å). The mean distance d¯_Mn—O = 2.18Å was found for the radially distorted octahedra [MnO₆] in Mn₂P₄O₁₂ [C 2/c, Z = 4, a = 12.065(1)Å, b = 8.468(1)Å, c = 10.170(1)Å, β = 119.29(1)°, 2811 independent reflections, 85 variables, R1 = 0.025, wR2 = 0.072]. Powder reflectance spectra of the three pink coloured manganese(II) phosphates have been measured. The spectra show clearly the influence of the low‐symmetry ligand fields around Mn²⁺. Observed d—d electronic transition energies and the results of calculations within the framework of the angular overlap model (AOM) are in good agreement. Bonding parameters for the manganese‐oxygen interaction in [Mn²⁺O₆] chromophors as obtained from the AOM treatment (B, C, Trees correction α, e_σ, e_π) are discussed.     

Synthesis and Characterization of the New Copper Indium Phosphate Cu8In8P4O30

The system CuO/In₂O₃/P₂O₅ has been investigated using solid state reaction between CuO, In₂O₃ and (NH₄)₂HPO₄ in silica glass crucibles at 900 °C. The powder samples were characterized by X‐ray diffraction, thermal analysis and FT‐IR spectroscopy. Orange single crystals of the new quaternary phase were achieved by the process of crystallization with mineralizers in sealed silica glass ampoules. They were then analyzed with EDX and single‐crystal X‐ray analysis in which the composition Cu₈In₈P₄O₃₀ with the triclinic space group P$\bar{1}$ (No 2) with a = 7,2429(14) Å, b = 8,8002(18) Å, c = 10,069(2) Å, α = 103,62(3)°, β = 106,31(3)°, γ = 101,55(3)° and Z = 1 was found. The three‐dimensional framework consists of [InO₆] octahedra and distorted [CuO₆] octahedra, overcaped [InO₇] prisms and [PO₄] tetrahedra, also trigonal [(CuIn)O₅] bipyramids and distorted [(CuIn)O₆] octahedra, where copper and indium are partly exchanged against each other. Cu₈In₈P₄O₃₀ exhibits an incongruent melting point at 1023 °C.     

Untersuchungen an P4O7: Ein neues Darstellungsverfahren,Strukturdaten und schwingungsspektroskopische Charakterisierung

Investigations on P₄O₇: A New Route to Synthesis, Crystal Structure Data and Characterization by Vibrational Spectroscopy Synthesis of pure P₄O₇ in one step is achieved by oxidizing P₄O₆ in a closed system and oxygen buffered atmosphere. The complete set of crystal data is reported. An assignement of the vibrational spectra (Raman and IR) based on measurements on an oriented crystal and in comparison to P₄O₆ and P₄O₁₀ is proposed.     

Thermal Analysis of the System Li2WO4-Li4P2O7-WO3

The system Li₂WO₄-Li₄P₂O₇-WO₃ in the range of WO₃ contents of up to 60 mol % was studied by thermal analysis. In the examined range of the composition triangle, the crystallization fields of lithium tungstate and pyrophosphate, of congruently melting compound D (Li₂WO₄·WO₃), and of incongruently melting compound D ₂ (2Li₂WO₄·Li₄P₂O₇) were revealed, and the glass formation region was established. Low-melting compositions showing promise for synthesis of lithium-tungsten oxide bronzes were revealed.     

Degradation thermique et etude vibrationnelle de MII(NH4)4(P3O9)2x4H2O(M II=Cu2+, Ni2+, Co2+)

We have studied the thermal behaviour under atmospheric pressure of isotypic tetrahydrate cyclotriphosphates M^II(NH₄)₄(P₃O₉)₂x4H₂O (M ^II=Cu, Ni and Co), between 25 and 1400°C, by X-ray diffraction, thermal analyses (TG and DTA) and infrared spectrometry. This study shows that the series of the compounds M^II(NH₄)₄(P₃O₉)₂x4H₂O (M ^II=Cu, Ni and Co) after elimination of water, in two different stages, and ammonia leads, at 400°C to cyclotetraphosphate M₂ ^IIP₄O₁₂ crystallized and to a thermal residue with a formula H₄P₄O₁₂ which undergoes under a thermal degradation by evolving water and pentoxide phosphorus. The kinetic characteristics of the dehydration and elimination of ammonia have been determinated. The vibrational spectra of Cu(NH₄)₄(P₃O₉)₂x4H₂O were examined and interpreted, in the domain of the valency frequencies, on the basis of the crystalline structure of its isotypic compound Co(NH₄)₄(P₃O₉)₂x4H₂O whose cycle has the site symmetry C₁, of our results of the calculation of the IR frequencies and the successive isotopic substitutions of the equivalent atoms (3P, 3Oi and 6Oe belonging to the P₃Oi₃Oe₆ ring) of the P₃O₉ ³⁻ cycle with high symmetry D_3h. This revised version was published online in August 2006 with corrections to the Cover Date.     

Chemische,thermoanalytische und röntgenorgraphische Untersuchungen zur Bildung des β-Ca2[P2O7] aus dem Ca2[P4O12] · 4 H2O

Chemical, Thermoanalytical, and X-ray Investigations to the Formation of the β-Ca₂[P₂O₇] from the Ca₂[P₄O₁₂] · 4 H₂O The formation of β-Ca₂[P₂O₇] from Ca₂[P₄O₁₂] · 4 H₂O (modification I) proceeds crystallographically oriented in several steps: In one of these steps an X-ray amorphous phase is formed and simultaneously cyclotetraphosphate reorganizes to polyphosphate. The dehydration proceeds in 2 steps: At 120°C 3 molecules and at 220°C 1 molecule are lost, respectively. The formation of diphosphate from polyphosphate, which is connected with the loss of P₂O₅, takes place at 850°C according to high temperature Guinier.     

Oriented Formation of Pb2P2O7 from K2Pb[P4O12]

Cyclotetraphosphate K₂Pb[P₄O₁₂] transforms into the lead diphosphate Pb₂P₂O₇ crystallographically oriented by heating up to its transformation point at 537°C in a moist atmosphere. The oriented formation of diphosphate takes place by means of epitaxy.     

Die Kristallstruktur des Bleicyclotetraphosphat-2-Hydrats,Pb2P4O12 · 2H2O

Crystal Structure of Lead Cyclotetraphosphate-2-Hydrate, Pb₂P₄O₁₂ · 2H₂O By heating of Pb₂P₄O₁₂ · 4 H₂O crystals at 100°C, Pb₂P₄O₁₂ · 2 H₂O is formed topotactically. The triclinic crystals are twinned on (010). Space group: P1 , unit cell: a = 8.02 ± 0.02, b = 10.58 ± 0.02, c = 7.53 ± 0.02 Å, α = 98.8 ± 0.2, β = 108.7 ± 0.2, γ = 82.6 ± 0.3°. The crystal structure was determined by Patterson and Fourier methods and refined by least-squares calculations. The structure consists of two crystallographically different P₄O₁₂^4? ring anions, point symmetry 1 , connected by Pb and hydrogen bonds. Both Pb atoms are coordinated by eight oxygen atoms. The polyhedra of either Pb are interconnected by common edges forming sheets and chains. Pb(1) is joined with four, Pb(2) with five P₄O₁₂^4? anions.