High-temperature reactions in the Co<Subscript>3</Subscript>Cr<Subscript>4</Subscript>(PO<Subscript>4</Subscript>)<Subscript>6</Subscript>–Cr(PO<Subscript>3</Subscript>)<Subscript>3</Subscript> system

A new dichromium(III) cobalt(II) diphosphate(V) of the formula CoCr₂(P₂O₇)₂ was detected in the Co₃Cr₄(PO₄)₆–Cr(PO₃)₃ system. The new compound was obtained as a result of high-temperature solid-state reactions between CoCO₃, Cr₂O₃ and (NH₄)₂HPO₄ as well as between Cr(PO₃)₃ and Co₃Cr₄(PO₄)₆. CoCr₂(P₂O₇)₂ was characterized using XRD, DTA and IR methods. Results demonstrated that CoCr₂(P₂O₇)₂ crystallizes in the triclinic system and its unit cell parameters were calculated. Its infrared spectrum was presented. CoCr₂(P₂O₇)₂ melts incongruently at 1270±10 °C with a formation of solid α-CrPO₄. The compound Co₃Cr₄(PO₄)₆, component of the system under study, was obtained for the first time as a pure phase. Its thermal stability was also investigated. Co₃Cr₄(PO₄)₆ is stable in air up to 1410 ± 20 °C.     

A novel cobalt(II)-molybdenum(V) phosphate organic-inorganic hybrid polymer

A new organic-inorganic hybrid cobalt(II)-molybdenum(V) phosphate polymer incorporating piperazine (pip), (H₂pip)₃[Co₃Mo₁₂O₂₄(OH)₆(PO₄)₈(H_1.5pip)₄]·5(H₂O), was prepared under hydrothermal conditions. As revealed by single-crystal X-ray diffraction studies, the material is modular, built from a secondary building block composed of two anionic hexameric polyoxomolybdophosphate [Mo₆O₁₂(OH)₃(PO₄)₄]⁹⁻ moieties, bridged by a central octahedral Co²⁺ centre. The sandwich-type {Co[Mo₆O₁₂(OH)₃(PO₄)₄]₂}¹⁶⁻ dimers are connected via tetrahedral Co²⁺ metal centres, forming an infinite one-dimensional polymer. The compound constitutes the first example of a reduced sandwich-type cobalt-molybdenum phosphate in which the organic moiety (pip) is effectively coordinated to the inorganic backbone of the polymer, in this case via the tetrahedrally coordinated Co²⁺ centres. The magnetic behaviour of this material was investigated in the temperature range 4-298 K.     

Contributions on Thermal Behaviour and Crystal Chemistry of Anhydrous Phosphates. XXXIV [1] Oxygen Equilibrium Pressures in Ternary Systems M / P / O (M = Co,Ni) and Heats of Formation of Anhydrous Cobalt(II) and Nickel(II) Phosphates

Oxygen equilibrium pressures have been measured in the temperature range 800 °C to 1000 °C by coulometric/potentiometric techniques for several equilibrium regions in the ternary systems M / P / O (M = Co, Ni). In both systems oxygen coexistence pressures of three‐phase equilibrium solids phosphide/phosphate are about 3 to 5 orders of magnitude smaller than p(O₂) above the corresponding M_s / MO_s system. Heats of formation Δ_fH°₂₉₈ and standard entropies S°₂₉₈ for the phosphates have been obtained from 2^nd and 3^rd law evaluation of the temperature dependence of the oxygen coexistence pressures. Thermodynamic data from literature for the phosphides of cobalt and nickel and estimated heat capacities for the anhydrous phosphates Co₃(PO₄)₂, Co₂P₂O₇, Ni₃(PO₄)₂, Ni₂P₂O₇ and Ni₂P₄O₁₂ were used for these calculations. Thus obtained enthalpies and entropies are compared to results from thermodynamic modelling of observed solid phase equilibria in the ternary systems M / P / O (M = Co, Ni).     

Hydrothermal synthesis and structural characterization of two new reduced phosphomolybdates based on an organoamine template and copper ion

Two new compounds, (H₂en)₃(H₂enMe)₄(H₃O){Cu^I[Mo^V ₆O₁₂(OH)₃(HPO₄)(PO₄)₃]₂}?·?6H₂O (1) and (H₂enMe)₄{Cu^ICu^II[Mo^V ₆O₁₂(OH)₃(PO₄)(HPO₄)₂(H₂PO₄)]₂}?·?3H₂O (2), were hydrothermally synthesized and characterized by elemental analysis, IR, TGA, and single-crystal X-ray diffraction analysis. Crystallographic analysis reveals that 1 is constructed from cluster anions {Cu^I[Mo^V ₆O₁₂(OH)₃(HPO₄)(PO₄)₃]₂}^15?, protonated organic amines, and water molecules. Each cluster is bridged through hydrogen bonds to form a 3-D supermolecular structure. For 2, {Cu^I[Mo^V ₆O₁₂(OH)₃(PO₄)(HPO₄)₂(H₂PO₄)]₂}^11? are connected by Cu^II cations to form an infinite chain. The formation of 1 and 2 reveals that organoamines influence the structures of the crystals.     

Les systemes binaires AlPO4−M3PO4 (M=Li,Na, K)

The liquid-solid phase diagram of the binary systems AlPO₄?M₃PO₄(M=Li, Na, K) have been established. The additional compounds Na₃Al(PO₄)₂, Na₃Al₂(PO₄)₃ and K₃Al₂(PO₄)₃ have been found again. A new compound K₃Al(PO₄)₂ is observed. The melting point of Na₃PO₄ is 1545°C and K₃PO₄ does not melt up to 1700°C.     

Phase equilibria in the ternary system: MgONa2OP2O5: Partial system: Mg3(PO4)2Mg4Na(PO4)3Na4P2O7Mg2P2O7

The partial system Mg₃(PO₄)₂Mg₄Na(PO₄)₃Na₄P₂O₇Mg₂P₂O₇ in the ternary system MgONa₂OP₂O₅ was investigated using thermal and X-ray diffraction analyses and microscopy, and its phase diagram has been determined. In this range of composition, two binary phosphates occur: Mg₄Na(PO₄)₃ and Mg₆Na₈(P₂O₇)₅. The former melts incongruently (at 1155°C) and the latter does congruently (at 808°C). In the partial system of interest, the two sections Mg₄Na(PO₄)₃Mg₂P₂O₇ and Mg₄Na(PO₄)₃Mg₆Na₈(P₂O₇)₅ are studied, and their phase diagrams are established. The partial system is divided into three partial ternary systems in which two ternary eutectics and one ternary peritectic occur.     

Sodium‐ and Potassium‐Hydrate Melts Containing Asymmetric Imide Anions for High‐Voltage Aqueous Batteries

Aqueous Na‐ or K‐ion batteries could virtually eliminate the safety and cost concerns raised from Li‐ion batteries, but their widespread applications have generally suffered from narrow electrochemical potential window (ca. 1.23 V) of aqueous electrolytes that leads to low energy density. Herein, by exploring optimized eutectic systems of Na and K salts with asymmetric imide anions, we discovered, for the first time, room‐temperature hydrate melts for Na and K systems, which are the second and third alkali metal hydrate melts reported since the first discovery of Li hydrate melt by our group in 2016. The newly discovered Na‐ and K‐ hydrate melts could significantly extend the potential window up to 2.7 and 2.5 V (at Pt electrode), respectively, owing to the merit that almost all water molecules participate in the Na⁺ or K⁺ hydration shells. As a proof‐of‐concept, a prototype Na₃V₂(PO₄)₂F₃|NaTi₂(PO₄)₃ aqueous Na‐ion full‐cell with the Na‐hydrate‐melt electrolyte delivers an average discharge voltage of 1.75 V, that is among the highest value ever reported for all aqueous Na‐ion batteries.     

Einbau von Na2SO4 in die Hochtemperaturform des Na3PO4

Formation of Solid Solutions of Na₂SO₄ in the High-temperature Form of Na₃PO₄ The high-temperature form of Na₃PO₄ solves up to 70 mole-% Na₂SO₄ maintaining the type of crystal structure. The lattice constants increase from 742.3(1) pm (pure Na₃PO₄) to 749.1(2) pm for Na^3?x(PO₄)^?x(SO₄)_x (x = 0.7). The high-temperature form, in the case of pure Na₃PO₄ stable above 325°C, is stabilized at room-temperature by doping with small amounts of Na₂SO₄.     

Crystal Growth,Single‐Crystal Structure Refinement and Unusual Ligand‐Field Splittings of Lazulite‐Type Oxidephosphates MTi2O2(PO4)2 (M = FeII,CoII, NiII)

Single crystals of oxidephosphates MTi₂O₂(PO₄)₂ [M: Fe (dark red), Co (pinkish red), Ni (green)] with edge‐lengths up to 0.4 mm were grown by chemical vapour transport. FeTi₂O₂(PO₄)₂ and CoTi₂O₂(PO₄)₂ are isotypic to NiTi₂O₂(PO₄)₂. The crystal structure of the latter was previously solved from powder data [FeTi₂O₂(PO₄)₂ (data for CoTi₂O₂(PO₄)₂ and NiTi₂O₂(PO₄)₂ in brackets): monoclinic, P2₁/c, Z = 2, a = 7.394(3) (7.381(6), 7.388(4)) Å, b = 7.396(2) (7.371(5), 7.334(10)) Å, c = 7.401(3) (7.366(6), 7.340(3)) Å, β = 120.20(3) (120.26(6), 120.12(4))°, R₁ = 0.0393 (0.0309, 0.0539) wR₂ = 0.1154 (0.0740, 0.1389), 2160 (1059, 1564) independent reflections, 75 (76, 77) variables]. The single‐crystal study allowed improved refinement using anisotropic displacement parameters, yielded lower standard deviations for the structural parameters and revealed a small amount of cation disordering. Twinning and cation disordering within the structures are rationalized by a detailed crystallographic classification of the MTi₂O₂(PO₄)₂ structure type in terms of group‐subgroup relations. The structure is characterized by a three‐dimensional network of [PO₄] tetrahedra and [M^IITi₂O₁₂] groups formed by face‐sharing of [M^IIO₆] and [TiO₆] octahedra. Electronic absorption spectra of MTi₂O₂(PO₄)₂ in the UV/VIS/NIR region show rather large ligand‐field splittings for the strongly trigonally distorted chromophors [M^IIO₆] (M = Fe, Co, Ni) with interelectronic repulsion parameters beeing slightly smaller than in other phosphates. Interpretation of the spectra within the framework of the angular overlap model reveals a significant second‐sphere ligand field effect of Ti^IV ions on the electronic levels of the Ni^II and Co^II.     

Phase equilibrium relations in the binary systems LiPO3CeP3O9 and NaPO3CeP3O9

The LiPO₃CeP₃O₉ and NaPO₃CeP₃O₉ systems have been investigated for the first time by DTA, X-ray diffraction, and infrared spectroscopy. Each system forms a single 1:1 compound. LiCe(PO₃)₄ melts in a peritectic reaction at 980°C. NaCe(PO₃)₄ melts incongruently, too, at 865°C. These compounds have a monoclinic unit cell with the parameters: a = 16.415(6), b = 7,042(6), c = 9.772(7)Å; β = 126.03(5)°; Z = 4; space group $\text{C}{}_2\text{c}$ for LiCe (PO₃)₄; and a = 9.981(4), b = 13.129(6), c = 7.226(5) Å, β = 89.93(4)°, Z = 4, space group $\text{P2}{}_1\text{n}$ for NaCe(PO₃)₄. It is established that both compounds are mixed polyphosphates with chain structure of the type |M^I_IM^III_II (PO₃)₄|_∞M^I_I: alkali metal, M^III_II: rare earth.     

A series of borate-rich metalloborophosphates Na2[MB3P2O11(OH)]·0.67H2O (M=Mg, Mn, Fe, Co, Ni, Cu, Zn): Synthesis, structure and magnetic susceptibility

A series of metalloborophosphates Na₂[M^IIB₃P₂O₁₁(OH)]·0.67H₂O (M^II=Mg, Mn, Fe, Co, Ni, Cu, Zn) have been prepared hydrothermally and their structures have been solved by single-crystal diffraction techniques. They all crystallize in a hexagonal space group P6₃ and form a 3D microporous structure with 12-membered ring channels consisted of octahedral (M^IIO₆), tetrahedral (BO₄, PO₄) and triangular (BO₂(OH)) units, in which the counter Na⁺ cations and water molecules are located. The Na⁺ cations are mobile and can be exchanged by Li⁺ in a melt of LiNO₃. Their open frameworks are thermal stable up to about 500 °C. Completed solid solutions between two different transition metals can also be obtained. Magnetic properties of Na₂[M^IIB₃P₂O₁₁(OH)]·0.67H₂O (M^II=Mn, Co, Ni, Cu) have been investigated.     

Photocatalytic Reduction of Ag2SO4 by Dawson-Derived Sandwich Complex

Photocatalytic reduction of Ag^I₂SO₄ from aqueous solutions is observed in the presence of Dawson-derived sandwich type polyoxometalates (POMs) [M₄(P₂W₁₅O₅₆)₂]¹⁶⁻, M = Co²⁺, Ni²⁺ and Zn²⁺ as photocatalyst and an organic substrate (propan-2-ol) as sacrificial electron donor. The direct photochemical excitation of the Dawson-derived sandwich type polyoxometalates in the presence of propan-2-ol leads to its reduction. That first reduction step induces electron transfer to Ag⁺ ions to give Ag⁰ metal atoms which then form by aggregation colloidal metal nanoparticles stabilized by POM. In the case of [Co₄(P₂W₁₅O₅₆)₂]¹⁶⁻, TEM experiments reveal that the Ag_n particles obtained with a slight excess of Ag⁺ are almost spherical with size in the range 20 – 50 nm. However, in a large excess of Ag⁺, the obtained colloids are more oblate and assembled together to give larger aggregates.     

A new structure type of phosphate: Crystal structure of Na2Zn5(PO4)4

A new compound, Na₂Zn₅(PO₄)₄, was identified in the system ZnONa₂OP₂O₅ and high-quality crystal was obtained by the melt method. The crystal structure of this compound was solved by direct method from single crystal X-ray diffraction data. The structure was then refined anisotropically using a full-matrix least square refinement on F² and the refinement converged to R₁=0.0233 and wR₂=0.0544. This compound crystallizes in the orthorhombic system with space group Pbcn, lattice parameters a=10.381(2) Å, b=8.507(1) Å, c=16.568(3) Å and Z=4. The structure is made up of 3D [Zn₅P₄O₁₆]_n²ⁿ⁻ covalent framework consisting of [Zn₄P₄O₁₆]_n⁴ⁿ⁻ layers. The powder diffraction pattern of Na₉Zn₂₁(PO₄)₁₇ is explained by simulating a theoretical pattern with NaZnPO₄ and Na₂Zn₅(PO₄)₄ in the molar ratio of 1:4 and then by Rietveld refinement of experimental pattern. Na₂Zn₅(PO₄)₄ melts congruently at 855 °C and its conductivity is 5.63×10⁻⁹ S/cm.     

Magnetic and vibrational properties and crystal structure of Sr9.2Co1.3(PO4)7 with disordered arrangements of some strontium, cobalt, and phosphate ions

Solid solutions of Sr_9+xCo_1.5−x(PO₄)₇ were found in the compositional range of 0.05?x?0.30. The structure of Sr_9.2Co_1.3(PO₄)₇ (x=0.2) was determined from single crystal X-ray diffraction (space group (No. 166); Z=3; and ; ; ; ) and refined to R₁=0.0343 and wR₂=0.0633 for 586 reflections with I>2σ(I). Sr_9.2Co_1.3(PO₄)₇ is structurally related to β-Ca₃(PO₄)₂ and Sr₃(PO₄)₂ and has disordered arrangements of some Sr²⁺, Co²⁺, and PO₄³⁻ ions. Sr²⁺ ions at a 9e site are statistically disordered among four positions near the center of symmetry. Co²⁺ and Sr²⁺ ions are split along the c-axis to occupy a 6c site that is 75% vacant. The P1O₄ tetrahedra are orientationally disordered. Sr²⁺ ions at an 8-fold coordinated 18h site, Co²⁺ ions at an octahedral 3a site, and the P2O₄ tetrahedra are ordered in the structure of Sr_9.2Co_1.3(PO₄)₇. Features of Raman spectra are discussed in relation to the crystallographic structure of Sr_9.2Co_1.3(PO₄)₇ and in comparison with Raman spectra of β-Ca₃(PO₄)₂-type and Sr₃(PO₄)₂-type compounds. Sr_9.2Co_1.3(PO₄)₇ is paramagnetic between 2 and 300 K with an effective magnetic moment of 4.98μ_B per Co²⁺ ion.     

Synthesis and Crystal Structure of Two New Molydenum(V) Pyrophosphate Complexes

Two new reduced molybdenum pyrophosphates, Na₂₈[Na₂{(Mo₂O₄)₁₀(P₂O₇)₁₀(HCOO)₁₀}]·108H₂O ( 1 ) and Na₂₂(H₃O)₂[Na₄{(Mo₂O₄)₁₀(P₂O₇)₁₀(CH₃COO)₈(H₂O)₄}]·91H₂O ( 2 ) have been synthesized and characterized by single‐crystal X‐ray diffraction. Red crystals of 1 are triclinic, space group , with a = 17.946(4) Å, b = 18.118(4) Å, c = 21.579(4) Å, α = 114.47(3)°, β = 93.54(3)°, γ = 114.39(3)° and V = 5581.8(19) ų, and orange crystals of 2 are monoclinic, space group P2₁/n, with a = 21.467(4) Å, b = 23.146(5) Å, c = 24.069(5) Å, β = 101.76(3)° and V = 11708(4) ų. They are both constructed by Mo^V dimers ({Mo₂O₄(O_P)₄(HCOO)} in 1 , {Mo₂O₄(O_P)₄(CH₃COO)} and {Mo₂O₄(O_P)₄(H₂O)₂} in 2 ) and pyrophosphoric groups. Their structures can be described as two interconnected nonequivalent wheels which are approximately perpendicular, delimiting a large cavity. The larger wheel contains six Mo^V dimers, while the smaller one has four dimers.     

Bildung von Diphosphaten aus geschmolzenem Natriumtrimetaphosphat, 3. Mitt.

Zusammenfassung Beim Auflösen der Oxide von Ti(IV), Ni und Co in geschmolzenem Na₃P₃O₉ bilden sich die Diphosphate Na₂(TiO) P₂O₇, Na₂NiP₂O₇ und Na₂CoP₂O₇. Beim Auslaugen der erstarrten Schmelze mit Wasser tritt auch Na₂Co₃(P₂O₇)₂·4 H₂O auf; ein entsprechendes Hydrat wird auch bei Mn(II) gefunden. Außerdem bildet Mn (II) ein Polyphosphat [Mn (PO₃)₂] _n . — Beim Auflösen eines Gemisches aus SrO und PbO in wechselnden Mengenverhältnissen entstehen nebeneinander Mischkristalle von Na₂(Sr, Pb) P₂O₇ mit wechselndem Verhältnis Sr,Pb und von einem Ultraphosphat [(Sr, Pb) P₄O₁₁] _n mit dem konstanten Verhältnis Sr,Pb=0,66,0,34. — Die Polyphosphate von Mn und von Sr–Pb werden papierchromatographisch und IR-spektroskopisch untersucht. — Die Bildung von Diphosphaten aus einer Polyphosphatschmelze wird an Hand der hier und früher beschriebenen Befunde zu deuten versucht.

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On dissolving the oxides of Ti(IV), Ni or Co in molten Na₃P₃O₇ the diphosphates Na₂(TiO) P₂O₇, Na₂NiP₂O₇ and Na₂CoP₂O₇ are formed respectively. Mn(II) forms a polyphosphate [Mn(PO₃)₂] _n . On dissolving a mixture of SrO and PbO of varying ratio one obtains at the same time mixed crystals of Na₂(Sr,Pb)P₂O₇ with a variable ratio of Sr,Pb and an ultraphosphate [(Sr,Pb)P₄O₁₁] _n with a constant ratio Sr,Pb=0,66,0,34. An interpretation of the formation of diphosphates from a melt of polyphosphates is attempted, using the present and previous observations.

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Mit 1 Abbildung

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Herrn Prof. Dr.E. Hayek zum 60. Geburtstag gewidmet.     

The crystal structure of Na7Mg4.5(P2O7)4

The crystal structure of Na₇Mg_4.5(P₂O₇)₄ has been solved by direct methods from the three-dimensional X-ray data. The space group is $\text{P}\text{1}$. The crystal structure consists of Mg²⁺, Na⁺, and P₂O^4?₇ ions. One magnesium atom at symmetry center (0,0,0) and two sodium atoms at ±(?0.0421, ?0.0596, 0.2230) display occupation factors 0.5 each. A short interatomic distance between these Na⁺ and Mg²⁺ ions (1.80 ± 0.01 Å) excludes the occupation of both sites in the same unit cell. The crystal structure of Na₇Mg_4.5(P₂O₇)₄ consists of unit cells containing Na₈Mg₄(P₂O₇)₄ or Na₆Mg₅(P₂O₇)₄ with a statistical occurrence 1:1.Each Mg²⁺ ion is octahedrally coordinated by six O^2? ions at distances 1.979 – 2.270 Å. The coordination polyhedra around the Na⁺ ions are ill-defined. The bond angles POP in the P₂O^4?₇ groups are 126.6 and 133.6° (±0.3°). The final reliability factor R is 7.1%.     

Studies on the thermal decomposition of the silver group of alkali metal nitritocobaltates(III)

The thermal decomposition of nitritocobaltate(III) of the silver group of general formula M₂Ag[Co(NO₂)₆] (where M = K⁺, NH⁺₄, Rb⁺ or Cs⁺) has been investigated. Based on the thermal curves of the investigated compounds and chemical and diffractometric analysis, the mechanism of thermal decomposition has been determined. The results obtained indicate that the decomposition proceeds in three stages. As a result of decomposition in the first stage (300°C), nitrates of alkali metals, metallic silver and Co₃O₄ are formed. In the second stage (500°C), a partial decomposition of nitrates to alkali metal oxides occurs, and in the third stage the products are alkali metal oxides, silver and Co₃O₄. This paper also presents the dependence of the decomposition temperature of nitritocobaltates(III) of the silver group on the ionic radius of the outer-sphere cation.     

Self‐Assembly of [B‐SbW9O33]9− Subunit with Transition Metal Ions (Mn2+, Cu2+, Co2+) in Aqueous Solution: Syntheses,Structures and Magnetic Properties of Sandwich Type Polyoxometalates with Subvalent SbIII Heteroatom

Rational self‐assembly of Sb₂O₃ and Na₂WO₄, or (NH₄)₁₈[NaSb₉W₂₁O₈₆] with transition‐metal ions (Mn²⁺, Cu²⁺, Co²⁺), in aqueous solution under controlled conditions yield a series of sandwich type complexes, namely, Na₂H₂[Mn_2.5W_1.5(H₂O)₈(B‐β‐SbW₉O₃₃)₂]?32 H₂O (1) , Na₄H₇[Na₃(H₂O)₆Mn₃(μ‐OAc)₂(B‐α‐SbW₉O₃₃)₂]?20 H₂O (OAc=acetate anion) (2) , NaH₈[Na₂Cu₄Cl(B‐α‐SbW₉O₃₃)₂]?21 H₂O (3) , Na₈K[Na₂K(H₂O)₂{Co(H₂O)}₃(B‐α‐SbW₉O₃₃)₂]? 10 H₂O (4) , and Na₅H[{Co(H₂O)₂}₃W(H₂O)₂(B‐β‐SbW₉O₃₃)₂]?11.5 H₂O (5) . These structures are determined by using the X‐ray diffraction technique and further characterized by obtaining IR spectra and performing elemental analysis. Structure analysis reveals that polyoxoanions in 1 and 5 comprise of two [B‐β‐SbW₉O₃₃]^9? building units, whereas 2 , 3 , and 4 consist of two isomerous [B‐α‐SbW₉O₃₃]^9? building blocks, which are all linked by different transition‐metal ions (Mn²⁺, Cu²⁺, or Co²⁺) with different quantitative nuclearity. It should be noted that compound 2 represents the first one‐dimensional sinusoidal chain based on sandwich like tungstoantimonate building blocks through the carboxylate‐bridging ligands. Additionally, 3 is constructed from sandwiched anions [Na₂Cu₄Cl(B‐α‐SbW₉O₃₃)₂]^9? linked to each other to form an infinitely extended 2D network, whereas 5 shows an interesting 3D framework built up from offset sandwich type polyoxoanion [{Co(H₂O)₂}₃W(H₂O)₂(B‐β‐SbW₉O₃₃)₂]^6? linked by Co²⁺ and Na⁺ ions. EPR studies performed at 110 K and room temperature reveal that the metal cations (Mn²⁺, Cu²⁺, Co²⁺) reside in a square‐pyramidal geometry in 2 , 3 , and 4 . The magnetic behavior of 1 – 4 suggests the presence of weak antiferromagnetic coupling interactions between magnetic metal centers with the exchange integral J=?0.552 cm^?1 in 2 .     

手性纳米磷酸锌钠的热化学研究

Chirai sodium zincophosphate nanocrystalline has been prepared and characterized. The standard molar enthaipy of the following reaction 12Na3PO4·12H2O（s）＋ 12ZnSO4·7H2O（s）= Na12（Zn12P12O48）·12H2O（s）＋ 12Na2SO4（s）＋216H2O（1） was determined by solution reaction calorimetric at 298.15 K, and calculated to be 33.666±0.195 kl/mol. From the results and other auxiliary quantities, the standard enthalpy of formation for sodium zincophosphate nanocrystalline was derived to be △fHm^⊙ [Na12（Zn12P12O48）·12H2O（s）, 298.15 K] =- 24268.494 ± 0.815 kJ/mol.