K2TiSi3O9·H2O

Single crystals of dipotassium titanium trisilicate hydrate were synthesized and the crystal structure was refined using data from single‐crystal X‐ray diffraction. The structure is a three‐dimensional mixed framework and contains channels formed by six‐ and eight‐membered rings. K⁺ ions and water mol­ecules are located in the channels.     

Metastable phase equilibria in the systems K2SO4 + K2B4O7 + H2O and KCl + K2B4O7 + H2O at 308.15 K

Experimental studies on the metastable solubilities and physicochemical properties (density and refractive index) in the ternary systems K₂SO₄ + K₂B₄O₇ + H₂O and KCl + K₂B₄O₇ + H₂O at 308.15 K were determined with the method of isothermal evaporation. According to the experimental results, the phase diagrams of the two ternary systems were plotted. In the phase diagrams, there are both two isotherm evaporation curves, one eutectic point corresponding to K₂SO₄ + K₂B₄O₇ · 4H₂O, and KCl + K₂B₄O₇ · 4H₂O, respectively. Both of the ternary systems belong to a simple eutectic type, and neither double salts nor solid solutions formed in the ternary systems. A comparison of the stable and metastable phase diagrams of the ternary systems K₂SO₄ + K₂B₄O₇ + H₂O and KCl + K₂B₄O₇ + H₂O shows that the supersaturated phenomenon of potassium borate tetrahydrate is significant and easier to appear the metastable behavior.     

KCo(H2O)2BP2O8·0.48H2O and K0.17Ca0.42Co(H2O)2BP2O8·H2O: two cobalt borophosphates with helical ribbons and disordered (K,Ca)/H2O schemes

The two title compounds, potassium diaquacobalt(II) borodiphosphate 0.48‐hydrate and potassium–calcium(0.172/0.418) diaquacobalt(II) borodiphosphate monohydrate, were synthesized hydrothermally. They are new members of the borophosphate family characterized by _∞[BP₂O₈]³⁻ helices running along [001] and constructed of boron (Wyckoff position 6b, twofold axis) and phosphorus tetrahedra. The [CoBP₂O₈]⁻ anionic frameworks in the two materials are structurally similar and result from a connection in the ab plane between the CoO₄(H₂O)₂ coordination octahedra (6b position) and the helical ribbons. Nevertheless, the two structures differ in the disorder schemes of the K,Ca and H₂O species. The alkali cations in the structure of the pure potassium compound are disordered over three independent positions, one of them located on a 6b site. Its framework is characterized by double occupation of the tunnels by water molecules located on twofold rotation axes (6b) and a fraction of alkali cations; its cell parameters, compared with those for the mixed K,Ca compound, show abnormal changes, presumably due to the disorder. For the K,Ca compound, the K and Ca cations are on twofold axes (6b) and the channels are occupied only by disordered solvent water molecules. This shows that it is possible, due to the flexibility of the helices, to replace the alkali and alkaline earth cations while retaining the crystal framework.     

K2[Mo2O4(C2O4)2(H2O)2]·3H2O

The crystal and molecular structure of dipotassium di‐μ‐oxo‐bis[aqua(oxalato‐O¹,O²)oxomolybdenum(III)] trihydrate, K₂­[Mo₂O₄(C₂O₄)₂(H₂O)₂]·3H₂O, has been determined from X‐ray diffraction data. In the dimeric anion, which has approximate twofold symmetry, each Mo atom is in a distorted octahedral coordination, being bonded to one terminal oxo‐O atom, two bridging O atoms, two O atoms from the oxalato ligand and one from the water mol­ecule. Bond lengths trans to the multiple‐bonded terminal oxo ligand are larger than those in the cis position, confirming the trans influence as a generally valid rule.     

K4H2[SiW5Mo6Mn(H2O)O39]·22H2O的晶体结构

合成了一个锰硅钼钨四元取代含氧簇合物,用单晶X射线衍射方法测定了结构,该晶体属于四方晶系,空间群P4/mnc,a=14.119(3),c=12.496(4),V=2490.9(12)3,Mr=2862.70,z=2,Dc=3.817g*cm-3,μ=15.922mm-1,R=0.0462,wR=0.1232.锰硅钼钨阴离子中,中心SiO4四面体在C4轴的两个位置上是无序的.     

New coordination modes in potassium edta salts: K2[H2edta]·2H2O,K3[Hedta]·2H2O and K4[edta]·3.92H2O

Three potassium edta (edta is ethylenediaminetetraacetic acid, H₄Y) salts which have different degrees of ionization of the edta anion, namely dipotassium 2‐({2‐[bis(carboxylatomethyl)azaniumyl]ethyl}(carboxylatomethyl)azaniumyl)acetate dihydrate, 2K⁺·C₁₀H₁₄N₂O₈²⁻·2H₂O, (I), tripotassium 2,2′‐({2‐[bis(carboxylatomethyl)amino]ethyl}ammonio)diacetate dihydrate, 3K⁺·C₁₀H₁₃N₂O₈³⁻·2H₂O, (II), and tetrapotassium 2,2′,2′′,2′′′‐(ethane‐1,2‐diyldinitrilo)tetraacetate 3.92‐hydrate, 4K⁺·C₁₀H₁₂N₂O₈⁴⁻·3.92H₂O, (III), were obtained in crystalline form from water solutions after mixing edta with potassium hydroxide in different molar ratios. In (II), a new mode of coordination of the edta anion to the metal is observed. The HY³⁻ anion contains one deprotonated N atom coordinated to K⁺ and the second N atom is involved in intramolecular bifurcated N—H...O and N—H...N hydrogen bonds. The overall conformation of the HY³⁻ anions is very similar to that of the Y⁴⁻ anions in (III), although a slightly different spatial arrangement of the –CH₂COO⁻ groups in relation to (III) is observed, whereas the H₂Y²⁻ anions in (I) adopt a distinctly different geometry. The preferred synclinal conformation of the –NCH₂CH₂N– moiety was found for all edta anions. In all three crystals, the anions and water molecules are arranged in three‐dimensional networks linked via O—H...O and C—H...O [and N—H...O in (I) and (II)] hydrogen bonds. K...O interactions also contribute to the three‐dimensional polymeric architecture of the salts.     

Die Kristallstrukturen von K8Ta6O19 · 16H2O und K7NaTa6O19 · 14H2O

The Crystal Structures of K₈Ta₆O₁₉ · 16H₂O and K₇NaTa₆O₁₉ · 14H₂O By alkaline digestion of Ta₂O₅ with p.a. KOH transparent single crystals of the composition K₈Ta₆O₁₉ · 16H₂O are formed. When technical grade KOH is used, the same kind of synthesis yields crystals of the composition K₇NaTa₆O₁₉ · 14H₂O. The latter compound has been given the formula K₈Ta₆O₁₉ · 14H₂O until now. In both cases the isopolyoxoanion [Ta₆O₁₉]⁸ consists of six TaO₆-octahedra connected by edge sharing. This means that the heavy atom partial structure found by Lindquist et al. is confirmed. Additionally the complete structures including the atomic positions of the oxygen atoms of the polyanions as well as those of the cations and crystal water molecules (without hydrogen positions) are determined.     

Enthalpies of crystallization of NaCl,KCl, LiCl·H2O,MgCl2 6H2O,CaCl2 6H2O and BaCl2·2H2O from aqueous solution at 298.15 K

The enthalpies of crystallization of NaCl, KCl, LiCl·H₂O, MgCl₂·6H₂O, CaCl₂·6H₂O and BaCl₂·2H₂O from aqueous solution were determined by means of different calculation methods on the basis of the earlier-measured differential and integral enthalpies of solution of the above salts. The obtained crystallization enthalpies are discussed and compared with the appropriate literature data.

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Zusammenfassung Es wurden die Kristallisationenthalpien des NaCl, KCl, LiCl·H₂O, MgCl₂·6H₂O, CaCl₂·6H₂O und BaCl₂·2H₂O aus wässerigen Lösungen bestirnt. Es wurden vorher gemessene differenzierte und integrale Enthalpien von oben genannten gelösten Salze ausgenutzt, bei denen verschiedene Berechnungsmethoden angewandt wurden. Die gewonenen Kristallisationenthalpien wurden mit entsprechenden Literaturangaben erörtert und vergliechen.

     

K_(10)[H_2W_(12)O_(42)]·11H_2O的合成及晶体结构分析

在水溶液中反应制得无色透明的标题化合物单晶 ,单晶X -射线结构分析表明 ,属单斜晶系 ,空间群P2 1,晶胞参数 :a=1.15 47(2 )nm ,b =1.430 9(3)nm ,c =1.5 495 (3)nm ,β =10 5 .41(3)° ,V =2 .46 81(9)nm3,Z =2 ,Dc=4.6 39Mg/m3,对 5 45 4个独立衍射点 (I>2δ(I) )进行全矩阵最小二乘法修正后 ,可靠性因子R =0 .0 487     

Structure and Vibrational Spectra of a New Acidic Diphosphate K2Cu(H2P2O7)2·2H2O

Abstract

Crystals of the acidic diphosphate K2Cu(H2P2O7)2 · 2 H2O, dipotassium copper bis(dihydrogendiphosphate) dihydrate, obtained via two different syntheses, revealed by means of single-crystal X-ray diffraction to be polymorph within triclinic Pī (a = 6.8560(4), b = 7.3140(3), c = 7.5570(4) Å; α = 81.028(4)°, β = 72.327(5)°, γ = 83.697(5)°, V = 355.86(3)Å3) and orthorhombic Pnma (a = 9.8990(6), b = 10.7810(7), c = 13.4010(7) Å, α = β = γ = 90°, V = 1430.17(15) Å3) space groups. Both phases were analyzed by FT-IR and micro-Raman vibrational spectroscopy and interpreted using factor group analysis. No coincidences of majority of the Raman and infrared spectral bands of K2Cu(H2P2O7)2 · 2 H2O confirmed the centrosymmetric structure of these two materials. The vibrational spectra point to a bent POP bridge angle.