X‐ray and neutron powder diffraction analyses of Gly·MgSO4·5H2O and Gly·MgSO4·3H2O,and their deuterated counterparts

We have identified a new compound in the glycine–MgSO₄–water ternary system, namely glycine magnesium sulfate trihydrate (or Gly·MgSO₄·3H₂O) {systematic name: catena‐poly[[tetraaquamagnesium(II)]‐μ‐glycine‐κ²O:O′‐[diaquabis(sulfato‐κO)magnesium(II)]‐μ‐glycine‐κ²O:O′]; [Mg(SO₄)(C₂D₅NO₂)(D₂O)₃]_n}, which can be grown from a supersaturated solution at ∼350 K and which may also be formed by heating the previously known glycine magnesium sulfate pentahydrate (or Gly·MgSO₄·5H₂O) {systematic name: hexaaquamagnesium(II) tetraaquadiglycinemagnesium(II) disulfate; [Mg(D₂O)₆][Mg(C₂D₅NO₂)₂(D₂O)₄](SO₄)₂} above ∼330 K in air. X‐ray powder diffraction analysis reveals that the trihydrate phase is monoclinic (space group P2₁/n), with a unit‐cell metric very similar to that of recently identified Gly·CoSO₄·3H₂O [Tepavitcharova et al. (2012). J. Mol. Struct. 1018 , 113–121]. In order to obtain an accurate determination of all structural parameters, including the locations of H atoms, and to better understand the relationship between the pentahydrate and the trihydrate, neutron powder diffraction measurements of both (fully deuterated) phases were carried out at 10 K at the ISIS neutron spallation source, these being complemented with X‐ray powder diffraction measurements and Raman spectroscopy. At 10 K, glycine magnesium sulfate pentahydrate, structurally described by the `double' formula [Gly(d₅)·MgSO₄·5D₂O]₂, is triclinic (space group P, Z = 1), and glycine magnesium sulfate trihydrate, which may be described by the formula Gly(d₅)·MgSO₄·3D₂O, is monoclinic (space group P2₁/n, Z = 4). In the pentahydrate, there are two symmetry‐inequivalent MgO₆ octahedra on sites of symmetry and two SO₄ tetrahedra with site symmetry 1. The octahedra comprise one [tetraaquadiglcyinemagnesium]²⁺ ion (centred on Mg1) and one [hexaaquamagnesium]²⁺ ion (centred on Mg2), and the glycine zwitterion, NH₃⁺CH₂COO⁻, adopts a monodentate coordination to Mg2. In the trihydrate, there are two pairs of symmetry‐inequivalent MgO₆ octahedra on sites of symmetry and two pairs of SO₄ tetrahedra with site symmetry 1; the glycine zwitterion adopts a binuclear–bidentate bridging function between Mg1 and Mg2, whilst the Mg2 octahedra form a corner‐sharing arrangement with the sulfate tetrahedra. These bridged polyhedra thus constitute infinite polymeric chains extending along the b axis of the crystal. A range of O—H…O, N—H…O and C—H…O hydrogen bonds, including some three‐centred interactions, complete the three‐dimensional framework of each crystal.     

3Mg(OH)2·MgSO4·8H2O: A Metastable Phase in the System Mg(OH)2‐MgSO4‐H2O

In the course of investigations relating to magnesia oxysulfate cement the basic magnesium salt hydrate 3Mg(OH)₂ · MgSO₄ · 8H₂O (3–1–8 phase) was found as a metastable phase in the system Mg(OH)₂‐MgSO₄‐H₂O at room temperature (the 5–1–2 phase is the stable phase) and was characterized by thermal analysis, Raman spectroscopy, and X‐ray powder diffraction. The complex crystal structure of the 3–1–8 phase was determined from high resolution laboratory X‐ray powder diffraction data [space group C2/c, Z = 4, a = 7.8956(1) Å, b = 9.8302(2) Å, c = 20.1769(2) Å, β = 96.2147(16)°, and V = 1556.84(4) ų]. In the crystal structure of the 3–1–8 phase, parallel double chains of edge‐linked distorted Mg(OH₂)₂(OH)₄ octahedra run along [–110] and [110] direction forming a pattern of crossed rods. Isolated SO₄ tetrahedra and interstitial water molecules separate the stacks of parallel double chains.     

Penkvilksite‐2O: Na2TiSi4O11·2H2O

The crystal structure of synthetic penkvilksite‐2O, disodium titanium tetrasilicate dihydrate, Na₂TiSi₄O₁₁·2H₂O, a microporous titanosilicate, confirms the major features of a previous model that had been obtained by order–disorder (OD) theory from the known structure of penkvilksite‐1M. An important difference from the previous model involves the hydrogen bonding of the water molecule which, on the basis of a Raman spectrum and the finding of only one of the two H atoms, is proposed to be disordered about a fixed O–H direction. The structure of penkvilksite‐2O is based on (100) silicate layers linked by isolated TiO₆ octahedra to form a heteropolyhedral framework. The layer is strongly corrugated, based on interlaced spiral chains, and is crossed by two different channels that have an effective channel width of about 3 Å.     

A high‐pressure single‐crystal synchrotron diffraction study of NH4RbTe4O9·2H2O: stability of three different TeOx coordination polyhedra

The crystal structure of ammonium rubidium nonaoxotetratellurate(IV) dihydrate has been studied as a function of pressure up to 7.40 GPa. The ambient‐pressure structure is characterized by the co‐existence of three different Te—O polyhedra (TeO₃, TeO₄ and TeO₅), which are connected to form layers. NH₄⁺, H₂O and Rb⁺ are incorporated between the layers. Both the Rb1 position, which is located on a twofold axis, and the Rb2 position are partially occupied. The three different types of coordination polyhedra around Te⁴⁺ are stable up to at least 5.05 GPa. No phase transition is observed. The fit of the unit‐cell volume as a function of pressure gives a zero‐pressure bulk modulus of 34 (1) GPa with a zero‐pressure volume of V₀ = 2620 (4) ų [B′ = 1.4 (2)].     

Kristallstrukturbestimmung von NaHC2O4 · H2O

NaHC₂O₄ · H₂O crystallizes in space group P 1 with a₀ = 6,51, b₀ = 6,66, c₀ = 5,70 Å, α₀ = 95,0°, β₀ = 109,8°, γ₀ = 74,9° and Z = 2. The structure was solved by direct methods. The refinement was carried out with 679 reflections to R₁ = 7,7%. The angle between the O? C? O planes is 12,6°.     

[CoII4MoV12O28(OH)12(H2O)12]·12H2O: facilitating single‐crystal growth by deuteration

The structure of the neutral heterometal oxide cluster dodecaaqua‐di‐μ₃‐hydroxido‐deca‐μ₂‐hydroxido‐octacosaoxidotetracobalt(II)dodecamolybdenum(V) dodecahydrate, [Mo₁₂O₂₈(μ₂‐OH)₁₀(μ₃‐OH)₂{Co(H₂O)₃}₄], is virtually identical to the previously reported Ni^II analogue [Mo₁₂O₂₈(μ₂‐OH)₁₀(μ₃‐OH)₂{Ni^II(H₂O)₃}₄] [Müller, Beugholt, Kögerler, Bögge, Budko & Luban (2000). Inorg. Chem. 39 , 5176–5177], the first molecular magnet to exhibit signs of magnetostriction. The formation kinetics of the neutral cluster species, which is insoluble in water, can be significantly slowed by the use of deuterated reactants in order to grow single crystals of sufficient size for single‐crystal X‐ray diffraction studies using standard diffractometers. One half of the main cluster and six solvent water molecules constitute the asymmetric unit. The main cluster is located on a mirror plane.     

Co0.50VOPO4·2H2O

The crystal structure of cobalt vanadophosphate dihydrate {systematic name: poly[diaqua‐μ‐oxido‐μ‐phosphato‐hemicobalt(II)vanadium(II)]}, Co_0.50VOPO₄·2H₂O, shows a three‐dimensional framework assembled from VO₅ square pyramids, PO₄ tetrahedra and Co[O₂(H₂O)₄] octahedra. The Co^II ions have local 4/m symmetry, with the equatorial water molecules in the mirror plane, while the V and apical O atom of the vanadyl group are located on the fourfold rotation axis and the P atoms reside on sites. The PO₄ tetrahedra connect the VO₅ polyhedra to form a planar P–V–O layer. The [Co(H₂O)₄]²⁺ cations link adjacent P–V–O layers via vanadyl O atoms to generate an unprecedented three‐dimensional open framework. Powder diffraction measurements reveal that the framework collapses on removal of the water molecules.     

复合物HNO···H2O2内N-H···O蓝移氢键的理论研究

A theoretical study on the blue-shifted H-bond N-H…O and red-shifted H-bond O-H…O in the complexHNO…H_2O_2 was conducted by employment of both standard and counterpoise-corrected methods to calculate thegeometric structures and vibrational frequencies at the MP2/6-31G(d),MP2/6-31 G(d,p),MP2/6-311 q G(d,p),B3LYP/6-31G(d),B3LYP/6-31 G(d,p) and B3LYP/6-311 G(d,p) levels.In the H-bond N-H…O,the calcu-lated blue shift of N-H stretching frequency is in the vicinity of 120 cm~(-1) and this is indeed the largest theoreticalestimate of a blue shift in the X-H…Y H-bond ever reported in the literature.From the natural bond orbital analy-sis,the red-shifted H-bond O-H…O can be explained on the basis of the dominant role of the hyperconjugation.For the blue-shifted H-bond N-H…O,the hyperconjugation was inhibited due to the existence of significant elec-tron density redistribution effect,and the large blue shift of the N-H stretching frequency was prominently due tothe rehybridization of sp~n N-H hybrid orbital.     

Preparation and crystal data for two trimetaphosphate tellurates: Te(OH)6 · 2Na3P3O9 · 6H2O and Te(OH)6 · K3P3O9 · 2H2O

Te(OH)₆ · 2Na₃P₃O₉ · 6H₂O, is hexagonal (P6₃/m) with a = 11,67(1), c = 12,12(1) Å, Z = 2 and D_x = 2,225 g/cm³. Te(OH)₆ · K₃P₃O₉ · 2H₂O, is monoklin (P2₁/c) with a = 19,61(5), b = 7,456(1), c = 14,84(6) Å, = 108,01(4), Z = 4 and D_x = 2,506 g/cm³. Both compounds are the first examples of phosphate tellurates in which the anion phosphate is condensed to the ring anion P₃O₉. As in phosphate tellurates already described the phosphate groups are independent of the TeO₆ octahedra.     

Cu3V10O28·24H2O and CuNa4V10O28·23H2O

The crystal structures of tricopper decavanadate tetracosa­hydrate, (I), and copper tetra­sodium decavanadate tricosa­hydrate, (II), have been determined by single‐crystal X‐ray diffraction. Both compounds exhibit a catenary structure consisting of [V₁₀O₂₈]⁶⁻ anions linked by Cu²⁺ cations in (I) or by Na⁺ cations in (II). Compound (II) also contains a polymeric linear array of edge‐sharing [Na(OH₂)₆]⁺ and [Cu(OH₂)₆]²⁺ octahedra. In both compounds, the [V₁₀O₂₈]⁶⁻ ions lie about inversion centres and the Cu²⁺ ions in (I) also lie about inversion centers.     

RbCrIII(C2O4)2·2H2O,Cs2Mg(C2O4)2·4H2O and Rb2CuII(C2O4)2·2H2O: three new complex oxalate hydrates

Rubidium chromium(III) dioxalate dihydrate [di­aqua­bis(μ‐oxalato)­chromium(III)­rubidium(I)], [RbCr(C₂O₄)₂(H₂O)₂], (I), and dicaesium magnesium dioxalate tetrahydrate [tetra­aqua­bis(μ‐oxalato)­magnesium(II)­dicaesium(I)], [Cs₂Mg(C₂­O₄)₂(H₂O)₄], (II), have layered structures which are new among double‐metal oxalates. In (I), the Rb and Cr atoms lie on sites with imposed 2/m symmetry and the unique water molecule lies on a mirror plane; in (II), the Mg atom lies on a twofold axis. The two non‐equivalent Cr and Mg atoms both show octahedral coordination, with a mean Cr—O distance of 1.966 Å and a mean Mg—O distance of 2.066 Å. Dirubid­ium copper(II) dioxalate dihydrate [di­aqua­bis(μ‐oxalato)­copper(II)­dirubidium(I)], [Rb₂Cu(C₂O₄)₂(H₂O)₂], (III), is also layered and is isotypic with the previously described K₂‐ and (NH₄)₂Cu^II(C₂O₄)₂·2H₂O compounds. The two non‐equivalent Cu atoms lie on inversion centres and are both (4+2)‐coordinated. Hydro­gen bonds are medium‐strong to weak in the three compounds. The oxalate groups are slightly non‐planar only in the Cs–Mg compound, (II), and are more distinctly non‐planar in the K–Cu compound, (III).     

Reinvestigation of Ge4Se9 based on single‐crystal data

Tetra­germanium nona­selenide, Ge₄Se₉, adopts a two‐dimensional layered structure. The layer is made up of infinite chains of corner‐sharing GeSe₄ tetra­hedra and the chains are connected via the Ge₂Se₇ unit to form the two‐dimensional layer. These layers are stacked to form the three‐dimensional structure with a van der Waals gap. A previous structure report on Ge₄Se₉ based on powder diffraction data [Fjellvåg, Kongshaug & Stølen (2001). J. Chem. Soc. Dalton Trans. pp. 1043–1045] is comparable with our results except for the absolute structure determination.     

Synthetic mansfieldite,AlAsO4·2H2O

Hydro­thermally prepared mansfieldite, AlAsO₄·2H₂O (aluminium arsenate dihydrate), contains a vertex‐sharing three‐dimensional network of cis‐AlO₄(H₂O)₂ octahedra and AsO₄ tetrahedra [d_av(Al—O) = 1.907 (2) Å, d_av(As—O) = 1.685 (2) Å and θ_av(Al—O—As) = 134.5 (1)°].     

Na2Co(H2PO4)4·4H2O

In the title compound, disodium cobalt tetrakis­(dihydrogen­phosphate) tetrahydrate, the Co^II ion lies on an inversion centre and is octahedrally surrounded by two water molecules and four H₂PO₄ groups to give a cobalt complex anion of the form [Co(H₂PO₄)₄(OH₂)]^2?. The three‐dimensional framework results from hydrogen bonding between the anions. The relationship with the structures of Co(H₂PO₄)₂·2H₂O and K₂CoP₄O₁₂·5H₂O is discussed.     

Zur Koordination des Aluminiums in den Calciumaluminathydraten 2 CaO · Al2O3 · 8 H2O und CaO · Al2O3 · 10 H2O

On the Coordination of Al in the Calcium Aluminate Hydrates 2 CaO · Al₂O₃ · 8 H₂O and CaO · Al₂O₃ · 10 H₂O By investigations with high-resolution ²⁷Al-NMR in solids it is shown that in the compound 2 CaO · Al₂O₃ · 8 H₂O the Al merely exist in octahedral coordination. According to this and considering its structural relationship with 4 CaO · Al₂O₃ · 19 H₂O the dicalcium aluminate hydrate is proposed to be formulated as [Ca₂Al(OH)₆][Al(OH)₃ (H₂O)₃]OH. Likewise for the compound CaO · Al₂O₃ · 10 H₂O the octahedral coordination of the Al is proved by ²⁷Al-NMR. This result corresponds with literature according to which a constitution as cyclohexaaluminate Ca₃[Al₆(OH)₂₄] · 18 H₂O is proposed.     

Fully automatic and precise data analysis developed for time‐of‐flight mass spectrometry

Scientific objectives of current and future space missions are focused on the investigation of the origin and evolution of the solar system with the particular emphasis on habitability and signatures of past and present life. For in situ measurements of the chemical composition of solid samples on planetary surfaces, the neutral atmospheric gas and the thermal plasma of planetary atmospheres, the application of mass spectrometers making use of time‐of‐flight mass analysers is a technique widely used. However, such investigations imply measurements with good statistics and, thus, a large amount of data to be analysed. Therefore, faster and especially robust automated data analysis with enhanced accuracy is required. In this contribution, an automatic data analysis software, which allows fast and precise quantitative data analysis of time‐of‐flight mass spectrometric data, is presented and discussed in detail. A crucial part of this software is a robust and fast peak finding algorithm with a consecutive numerical integration method allowing precise data analysis. We tested our analysis software with data from different time‐of‐flight mass spectrometers and different measurement campaigns thereof. The quantitative analysis of isotopes, using automatic data analysis, yields results with an accuracy of isotope ratios up to 100 ppm for a signal‐to‐noise ratio (SNR) of 10⁴. We show that the accuracy of isotope ratios is in fact proportional to SNR⁻¹. Furthermore, we observe that the accuracy of isotope ratios is inversely proportional to the mass resolution. Additionally, we show that the accuracy of isotope ratios is depending on the sample width T _s by T _s^0.5. Copyright © 2017 John Wiley & Sons, Ltd.     

Earth Alkaline Tetrathiosquarates: Syntheses and Crystal Structures of MgC4S4 · 6 H2O and CaC4S4 · 4 H2O

Concentrated aqueous solutions of magnesium chloride and calcium nitrate, respectively, allow on addition of the potassium salt of tetrathiosquarate, K₂C₄S₄ · H₂O, the isolation of the earth alkaline salts MgC₄S₄ · 6 H₂O ( 1 ) and CaC₄S₄ · 4 H₂O ( 2 ) as orange and red crystals. The crystal structure determinations ( 1 : monoclinic, C2/c, a = 17.2280(7), b = 5.9185(2), c = 13.1480(4) Å, β = 104.730(3)°, Z = 4; 2 : monoclinic, P2₁/m, a = 7.8515(3), b = 12.7705(5), c = 10.6010(4) Å, β = 93.228(2)°, Z = 4) show the presence of C₄S₄^2? ions with almost undistorted D_4h symmetry having average C–C and C–S bond lengths of 1.451Å and 1.659Å for 1 and 1.451Å and 1.655Å for 2 . The structure of 1 contains discrete, octahedral [Mg(H₂O)₆]²⁺ complexes. Several O–H····O and O–H····S bridges with H····O and H····S distances of less than 2.50Å connect cations and anions. The structure of 2 is built of concatenated, edge‐sharing Ca(H₂O)₆S₂ polyhedra. The Ca²⁺ ions have the coordination number eight, C₄S₄^2? act as a chelating ligands towards Ca²⁺ with Ca–S distances of 3.14Å. The infrared and Raman spectra show bands typical for the molecular building units of the two compounds.