Structure of the complex [trans-SnF4(H2O)2· (18-crown-6)· 2H2O]

The molecular and crystal structure of the title complex (I) obtained by addition of tin fluoride in a hydrofluoric acid solution to 18-crown-6 in methanol was investigated by X-ray structure analysis. The crystals are monoclinic, space group P2₁/n, a = 13.497(3), b = 7.806(2), c = 9.892(2) Å, β = 95.57(3)°, Z = 2 for C₁₂H₃₂F₄O₁₀Sn. In the polymer chain, the crown ether molecules alternate with the inorganic complexes [trans-SnF₄(H₂O)₂] and are linked to them by O-H...O type hydrogen bonds involving the intermediate water molecules. The weak C-H...F interactions bind the chains into the layers which are parallel to the xz plane.     

An analysis of the vibrational frequencies and amplitudes of the H5O+2 ion in H4SiW12O40·6H2O (TSA·6H2O) and H3PW12O40·6H2O (TPA·6H2O)

The infrared, Raman and inelastic neutron scattering (INS) spectra of TSA·6H₂O and TPA·6H₂O are in agreement with those expected for the presence of H₅O⁺₂ ions. Force fields for different assignment schemes are compared with the observed vibrational frequencies and the INS spectral profile. All but two schemes are eliminated. Whilst low-resolution INS spectroscopy cannot distinguish between these two schemes, the orientations of the vibrational ellipsoids for one scheme are in better agreement with those reported from low-temperature crystallographic studies of the H₅O⁺₂ ion.     

Synthesis and Crystal Structure of [Ni(H2O)6][Ni(H2O)2(C4H2O4)]·4H2O

Reaction of a freshly prepared Ni(OH)_{2?2 x} (CO₃) _x ·yH₂O with maleic acid in H₂O at room temperature afforded [Ni(H₂O)₆][Ni(H₂O)₂(C₄H₂O₄)]·4H₂O, which consists of [Ni(H₂O)₆]²⁺ cations, [Ni(H₂O)₂(C₄H₂O₄)]^2? anions and lattice H₂O molecules. Ni atoms in cations are octahedrally coordinated and Ni atoms in anions are each octahedrally coordinated by bidentate chelating maleato ligands and two water molecules at trans positions. Cations and anions are interlinked by hydrogen bonds to form 1D chains, which are hexagonally arranged and connected by the lattice water molecules. When heated in a flowing argon stream, the compound decomposes, with complete dehydration being followed by dissociation of nickel maleate into NiO and maleic anhydride.     

On the thermal decomposition of [Fe2NiO(CH3COO)6(H2O)3]·2H2O

The heteronuclear-oxoacetate with the composition [Fe₂NiO(CH₂COO)₆(H₂O)₃]·2H₂O decomposed on heating, forming nickel ferrite NiFe₂O₄ and (depending on the decomposition conditions) in part other solid phases. H₂O, CH₃COOH, acetone and CO₂ were also formed in the decomposition. A reaction scheme is given for the decomposition. The products were porous powders with grain diameters between 3 and 10m. On increase of the temperature of decomposition from 300 to 800 C, the BET surface area and the surface area of the pores decreased, but only a small alteration in grain size was observed. As a result of thermal treatment in the temperature region abone 800C, larger aggregates of grains were formed in sintering processes.

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Zusammenfassung Heteronukleare-Oxoazetate der Zusammensetzung [Fe₂NiO(CH₃COO)₆(H₂O)₃]·2H₂O werden durch Erhitzen zersetzt, wobei Nickelferrite NiFe₂O₄ und — in AbhÄngigkeit von den Bedingungen der Zersetzung — mit einem Teil anderer fester Phasen gebildet wird. In der Zersetzungsreaktion werden auch H₂O, CH₃COOH, Azeton und CO₂ gebildet. Es wird ein Reaktionsschema für die Zersetzung angegeben. Die Produkte sind poröse Pulver mit einem Korndurchmesser zwischen 3 und 10 m. Wird die Zersetzungstemperatur von 300 auf 800C erhöht, nimmt die BET-OberflÄche und die PorenoberflÄche ab, wobei sich die Korngrö\e aber nur wenig verÄndert. Im Ergebnis der WÄrmebehandlung im Temperaturbereich oberhalb 800C werden durch Sinterprozesse grö\ere Partikelaggregate gebildet.

     

Unexpected size distribution of Ba(H2O)n clusters: why is the intensity of the Ba(H2O)1 cluster anomalously low?

An experimental and theoretical study on the reactivity of neutral Ba atoms with water clusters has been conducted to unravel the origin of the irregular intensity pattern observed in one-photon ionization mass spectra of a Ba(H(2)O)(n)/BaOH(H(2)O)(n-1) (n = 1-4) cluster distribution, which was generated in a laser vaporization-supersonic expansion source. The most remarkable irregular feature is the finding for n = 1 of a lower intensity for the Ba(+)(H(2)O)(n) peak with respect to that of BaOH(+)(H(2)O)(n-1), which is opposite to the trend for n = 2-4. Rationalization of the data required consideration of a distinct behavior of ground-state and electronically excited state Ba atoms in inelastic and reactive Ba + (H(2)O)(n) encounters that can occur in the cluster source. Within this picture, the generation of Ba(H(2)O)(n) (n > 1) association products results from stabilizing collisions with atoms of the carrier gas, which are favored by intramolecular vibrational redistribution that operates on the corresponding collision intermediates prior to stabilization; the latter is unlikely to occur for Ba + (H(2)O) encounters. Overall, this interpretation is consistent with additional in-source laser excitation and quenching experiments, which aimed to explore qualitatively the effect of perturbing the Ba atom electronic state population distribution on the observed intensity pattern, as well as with the energetics of various possible reactions for the Ba + H(2)O system that derive from high level ab initio calculations.     

Structure of (C3H5NH3)2H2P2O7·H2O

The bis(cyclopropylammonium)dihydrogenodiphosphate monohydrate is a new diphosphate associated with the organic molecule C₃H₅NH₂. We report the chemical preparation and the crystal structure of this organic cation diphosphate. (C₃H₅NH₃)₂H₂P₂O₇.H₂O is orthorhombic (S.G. : P2₁2₁2₁), with Z = 4 and the following unit-cell parameters : a = 4.828(1) Å, b = 11.011(1) Å, c = 25.645(2) Å. The P₂O₇ groups and H₂O water molecules form a succession of bidimensional layers perpendicular to the c axis. The organic cations ensure the three-dimensional cohesion by NH-O hydrogen bonds.     

Syntheses and structures of p-HOOCC6F4COOH · H2O (H2L · H2O) and luminescent coordination polymers [Tb2(H2O)4(L)3 · 2H2O] n and Tb2(Phen)2(L)3 · 2H2O

Compounds p-HOOCC₆F₄COOH · H₂O (H₂L · H₂O), [Tb₂(H₂O)₄(L)₃ · 2H₂O] _n (I), and Tb₂(Phen)₂(L)₃ · 2H₂O (II) are synthesized. According to the X-ray structure analysis data, the crystal structure of H₂L · H₂O is built of centrosymmetric molecules H₂L and molecules of water of crystallization. The crystal structure of compound I is built of layers of coordination 2D polymer [Tb₂(H₂O)₄(L)₃] _n and molecules of water of crystallization. The ligands are the L^2? anions performing both the tetradentate bridging and pentadentate bridging-chelating functions. The coordination polyhedron TbO₉ is a distorted three-capped trigonal prism. Acid H₂L manifests photoluminescence in the UV region (??_max = 368 nm). Compounds I and II have the green luminescence characteristic of the Tb³⁺ ions, and the band with ??_max = 545 nm (transition ⁵ D ₄?? ⁷ F ₅) is maximum in intensity. The photoluminescence intensity of compound II is higher than that for compound I.     

Kinetics of decomposition of the liquid phase of the ternary system LiOH-H2O2-H2O in the presence of the solid phase of Li2O2 · H2O

The kinetics of decomposition of hydrogen peroxide in the liquid phase of the ternary system LiOH-H₂O₂-H₂O was studied in the presence the solid phase of Li₂O₂·H₂O and without it. The main kinetic parameters of the processes studied were determined.     

Observation of the novel “three-pointed star” cage-like (H2O)5 cluster in a polymeric solid {[Ag2(bpp)2(H2O)2](chd)·9H2O} n

Coordination polymeric solid, {[Ag₂(bpp)₂(H₂O)₂](chd)·9H₂O} _n (1) (bpp = 1,3-bis(4-pyridyl) propane, H₂chd = 1,4-cyclo-hexanedicarboxylic acid), has been obtained by the solution phase ultrasonic synthesis techniques. The structure established through X-ray structural analysis shows that the compound traps an interesting 1D water tape built by the alternating ??three-pointed star?? cage-like pentameric and D _2h tetrameric clusters (C2/c, Z = 4; a = 30.37(2) ?, b = 9.271(5) ?, and c = 18.89(1) ?; ?? = 128.47°; V = 4164(4) ?³). The novelty of the present complex is the rarely crystallographic example of the cage-shaped water pentamer, which is usually ascribed to a less-stable species. A first-principle density functional theory (DFT) calculation demonstrates that the interconnectivity between cage-like pentamers and D _2h tetramers is beneficial for contribution to the structural stabilization of these less-stable water cluster species.     

XPS study of the electronic structure of heterometallic complexes [Fe2MO(O2CCH3)6(H2O)3] · 3H2O (M = Co,Ni)

Heterometallic compounds of general formula [Fe ₂ ^III M^IIO(O₂CR)₆(H₂O)₃] · 3H₂O (R = CH₃, M = Co, Ni; R = CCl₃, M = Co, Ni) have been studied by XPS. The compounds have been identified as high-spin complexes with metal atoms in oxidation states M(II) and M(III). Analysis of the XPS data revealed the tendency of the XPS pattern and magnetic parameters of molecules to change with a change in the electronic nature of metal atoms. The assignment is based on the degree of covalence of the M-O bond. In chloro-substituted heterocomplexes, electron density delocalization on the metal atoms with metal-to-ligand charge transfer through three bonds (M-O-C-C) is observed. The substitution in terminal groups leads to the change in the electron density distribution between the carboxylate and terminal groups.     

Identification of the cobalt(II) chloride ‘mixed’ solvate Co4Cl8(H2O)4(MeCN)6: the ionic structure trans-[Co(H2O)2(MeCN)4] trans-[Co(H2O)2(MeCN)2(CoCl4)2]

The structure of the title compound features mononuclear octahedral Co^II cations, trans-[Co(H₂O)₂(MeCN)₄]²⁺, and trinuclear anions, trans-[Co(H₂O)₂(MeCN)₂(CoCl₄)₂]^2–; the latter centrosymmetric units contain a central octahedral Co(H₂O)₂(MeCN)₂ moiety with two tetrahedral [CoCl₄]^2– ligands. These two large ions are held in a network of intra- and inter-molecular hydrogen bonding.     

Crystal structure of Na2[(UO2)2(SeO4)3(H2O)2] · 6.5H2O

The compound Na₂[(UO₂)₂(SeO₄)₃(H₂O)₂] · 6.5H₂O (I) is studied using X-ray diffraction. The compound crystallizes in the monoclinic crystal system with the unit cell parameters a = 19.7366(8) Å, b = 10.8206(4) Å, c = 21.3577(8) Å, β = 103.4311(1)°, Z = 4, and the space group P2₁/c, R ₁ = 0.0379. Compound I is found to be a representative of the crystal-chemical group A₂T ₂ ³ B²M ₂ ¹ (A = UO ₂ ²⁺ ) of uranyl complexes and contains the cage group [(UO₂)₂(SeO₄)₃(H₂O)₂]^2?.     

Synthesis and characteristics of the dioxonium salt based on tartratogermanate acid. Crystal and molecular structure of (H5O2)[(H2O)2Ge(μ-Tart)2Ge(OH)] · 4H2O

Tartratogermanate acid was obtained for the first time as the dioxonium complex (H₅O₂)[(H₂O)₂Ge(??-Tart)₂Ge(OH)] · 4H₂O (I) by the reaction of germanium tetrachloride with D-tartaric acid (H₄Tart) in 85% acetic acid. The complex was characterized by elemental analysis data, thermogravimetry, and IR spectroscopy. X-ray diffraction analysis for I was performed. The crystals are orthorhombic, a = 15.862(3) ?, b = 13.401(3) ?, c = 8.6800(17) ?, V = 1845.1(6) ?³, Z= 4, space group P2₁2₁2, R1= 0.0520 for 5152 reflections with I > 2??(I). Compound I is composed of the dimeric complex anions [(H₂O)₂Ge(??-Tart)₂Ge(OH)]^?, dioxonium cations, and water molecules of crystallization. In the anion, the Ge(1) (CN = 6) and Ge(2) (CN = 5) atoms are linked by two chelating bridging fully deprotonated tartaric acid ligands through two carboxyl (average Ge-O, 1.883(4) and 1.893(4) ?, respectively) and two alcohol (average Ge-O, 1.859(4) and 1.779(4) ?, respectively) oxygen atoms. The coordination polyhedron of Ge (1) is completed to a distorted octahedron by the oxygen atoms of two water molecules (Ge(1)-O(H₂O), 1.933(4) and 1.854(3) ?). The Ge(2) coordination polyhedron is trigonal bipyramid. Its base is formed by two alcohol oxygen atoms of two bridging Tart^4? ligands and the oxygen atom of the terminal hydroxy group (Ge-O, 1.764(4) ?). The axial positions are occupied by the carboxyl oxygen atoms of the Tart^4? ligands (the O(5)Ge(2)O(11), 176.84(16)°). In the crystal, the structural units are combined by hydrogen bonds to a three-dimensional framework.     

Measurement and explanation of the d-d transition spectra of [Cu(o-phen)(ox) · H2O] · H2O

Aqua (1-10-phenanthroline)-(oxalato-O′O″) copper(II) monohydrate crystals have been prepared and characterized by elemental analysis, thermal analysis, infrared and electronic absorption spectrum, the later involves a strong absorption band appearing at 15 560 cm⁻¹. The experimental results are discussed quantitatively using the ligand field theory (LFT) and radial wave function of non-free copper(II). The values of <r²>, <r⁴>, <r⁻³>, B, C and ζ_3d were calculated in the light of the crystal structure. The energy level of the title crystal was interpreted comprehensively. All of our research indicates that the mixed complex of o-phen and ox exists in two forms, as reported by P. O'Brien, C. Stafford and Cheng Young, Inorg. Chim. Acta 147, 3 (1988) [1].     

Synthesis and characterization of polymer eight-coordinate (enH2)[YIII(pdta)(H2O)](2)·10H2O as well as the interaction of [YIII(pdta)(H2O)]2(2-) with BSA

The eight-coordinate (enH2)[YIII(pdta)(H2O)](2)·10H2O (en=ethylenediamine and H4pdta=1,3-propylenediamine-N,N,N',N'-tetraacetic acid) was synthesized, meanwhile its molecular and crystal structures were determined by single-crystal X-ray diffraction technology. The interaction between [Y(III)(pdta)(H2O)]2(2-) and bovine serum albumin (BSA) was investigated by UV-vis and fluorescence spectra. The results indicate that [YIII(pdta)(H2O)]2(2-) quenched effectively the intrinsic fluorescence of BSA via a static quenching process with the binding constant (Ka) of the order of 10(4). Meanwhile, the binding and damaging sites to BSA molecules were also estimated by synchronous fluorescence. Results indicate that the hydrophobic environments around Trp and Tyr residues were all slightly changed. The thermodynamic parameters (ΔG=-25.20 kJ mol(-1), ΔH=-26.57 kJ mol(-1) and ΔS=-4.58 J mol(-1) K(-1)) showed that the reaction was spontaneous and exothermic. What is more, both ΔH and ΔS were negative values indicated that hydrogen bond and Van der Waals forces were the predominant intermolecular forces between [YIII(pdta)(H2O)]2(2-) and BSA.     

Crystal and molecular structure of the [Nd2(H2O)8(C6F5COO)6]·2H2O Compound

A compound with the composition Nd(C₆F₅COO)₃· H₂O (I) is prepared. Single crystals are grown, and their single crystal XRD analysis of the Nd₂(H₂O)₈(C₆F₅COO)₆]·2H₂O (II) compound is performed. The crystals are triclinic: a = 7.693(2) Å, b = 9.394(2) Å, c = 18.203(4) Å, α = 81.91(3)°, β = 84.41(3)°, γ = 88.97(3)°, Z = 1, d _x = 2.223 g/cm³. The structure is composed of symmetrical molecules of the binuclear [Nd₂(H₂O)₈(C₆F₅COO)₆] complex and crystallization water molecules. The C₆F₅COO^- ligands are monodentate and tridentate bridging- chelating, which results in a closure of two four-membered chelate cycles NdO₂C and a four-membered metal cycle Nd₂O₂. The NdO₉ polyhedron is a distorted one-capped tetragonal antiprism.     

Kinetics of the thermal dehydration of potassium titanium oxalate, K2TiO(C2O4)2·2H2O

The thermal dehydration reaction of potassium titanium oxalate, K₂TiO(C₂O₄)₂·2H₂O, has been studied by means of thermogravimetry (TG), differential thermal analysis (DTA), and differential scanning calorimetry (DSC) in nitrogen atmosphere at different heating rates. K₂TiO(C₂O₄)₂·2H₂O dehydrates in a single step through a practically irreversible process. The activation energy involved and its dependence on the conversion degree were estimated by evaluating the thermogravimetric data according to model-free methods, and values of activation energy were determined for the dehydration reaction. Activation energy values were also evaluated from DSC data using isoconversional methods. The complexity of the dehydration of K₂TiO(C₂O₄)₂·2H₂O is illustrated by the dependence of E on the extent of conversion, ?? (0.05??????????0.95).     

Synthesis of calcium titanate from [Ca(H2O)3]2[Ti2(O2)2O(NC6H6O6)2]·2H2O as a cheap single-source precursor

Calcium titanate (CaTiO₃) was conveniently synthesized by thermal decomposition of a single-source precursor [Ca(H₂O)₃]₂[Ti₂(O₂)₂O(NC₆H₆O₆)₂]·2H₂O at low temperature. This single-source precursor was characterized by elemental analysis, IR spectrum, thermal gravimetric analysis and X-ray single crystal diffraction. The calcined products at different temperature were further characterized by powder X-ray diffractions and IR spectra. The morphology, microstructure, and crystallinity of the resulting CaTiO₃ materials have been characterized by SEM and TEM. The BET measurement revealed that the CaTiO₃ powders had a surface area of 14.0 m²/g. In addition, the microwave dielectric properties of the resulting CaTiO₃ material have been measured.