Synthesis and Crystal Structure of KSc(HPO4)2

KSc(HPO₄)₂ was obtained by hydrothermal synthesis. The crystal structure was determined from single‐crystal X‐ray data: orthorhombic, space group Pnma (No. 62), a = 14.5095(10), b = 5.4260(4), c = 8.4882(5) Å, V = 668.26(8) ų and Z = 4. The crystal structure of KSc(HPO₄)₂ represents a new structure type containing twelve‐ and four‐membered rings forming channels along [010] built of alternating ScO₆ octahedra and HPO₄^2? groups. Potassium ions reside within the twelve membered ring channels.     

Synthesis and Characterization of the Synthetic Minerals Villyaellenite and Sarkinite,Mn5(AsO4)2(HAsO4)2 · 4H2O and Mn2(AsO4)(OH)

Using hydrothermal methods, two manganese arsenates have been synthesized and characterized by single crystal X‐ray diffraction. The products Mn₅(AsO₄)₂(HAsO₄)₂ ?4H₂O ( 1 ) and Mn₂AsO₄(OH) ( 2 ), the Mn end‐members of the minerals villyaellenite and sarkinite, respectively, have been obtained (crystal data 1 : monoclinic, C2/c, a = 18.109(4), b = 9.332(2), c = 9.809(2) Å, β = 96.172(4)?, Z = 4; 2 : monoclinic, P2₁/c, a = 10.219(2), b = 13.613(2), c = 12.780(2) Å, β = 108.834(2)?, Z = 16). In both compounds a three‐dimensional framework of edge‐sharing MnO polyhedra is observed. Based on the availability of the all Mn2containing form of villyaellenite ( 1 ), the ordering scheme of the impurity cations of the natural samples could be confirmed. Magnetic susceptibility measurements of 1 indicate the presence of high‐spin Mn²⁺ ions. The comparison of the data on sarkinite ( 2 ) with the data obtained from the natural sample indicates that the mineral has either a very high Mn content, or an absence of impurity cation ordering.     

EPR parameters and impurity structures for Cr3+ ions in KSc(MoO4)2, RbIn(MoO4)2 and RbSc(MoO4)2 crystals

The calculations of EPR parameters (g factors g||, g(perpendicular) and zero-field splitting D) related to the impurity structures have been made from the high-order perturbation formulas for Cr(3+) ions in trigonal KSc(MoO(4))(2), RbIn(MoO(4))(2) and RbSc(MoO(4))(2) crystals. It is found that the MO(6) octahedra in these crystals change from the trigonal elongation in the pure crystals to the trigonal compression in the impurity centers. The results are discussed.     

Mg7(AsO4)2(HAsO4)4: a new magnesium arsenate with a very strong hydrogen bond

A new compound, heptamagnesium bis­(arsenate) tetrakis(hydrogenarsenate), Mg₇(AsO₄)₂(HAsO₄)₄, was synthesized by a hydro­thermal method. The structure is based on a three‐dimensional framework of edge‐ and corner‐sharing MgO₆, MgO₄(OH)₂, MgO₅, AsO₃(OH) and AsO₄ polyhedra. Average Mg—O and As—O bond lengths are in the ranges 2.056–2.154 and 1.680–1.688 Å, respectively. Each of the two non‐equivalent OH groups is bonded to both an Mg and an As atom. One OH group is involved in a very short hydrogen bond [O⋯O = 2.468 (3) Å]. The formula unit is centrosymmetric, with all atoms in general positions except for one Mg atom, which has site symmetry . The compound is isotypic with Mn₇(AsO₄)₂(HAsO₄)₄ and M₇(PO₄)₂(HPO₄)₄, where M is Fe, Co or Mn.     

Molecular structure of tris(acetylacetonato)scandium Sc(C5H7O2)3

Molecular structure of tris(acetylacetonato)scandium, Sc(C₅H₇O₂)₃, is investigated by gas-phase electron diffractometry. The main structural parameters of the molecule are evaluated. The average internuclear distances and angles correspond to C₃ symmetry. The chief structural motif is trigonal antiprisms of six oxygen, carbon, and hydrogen atoms with a scandium atom at the center. It is found that r_g(Sc-O) = 204.1(8) pm and r_g(C-O) = 124.7(4) pm. Translated fromZhumal Strukturnoi Khimii, Vol. 39, No. 4, pp. 633–639, July–August, 1998.     

KZn(HP2O7)·2H2O and KMn(HP2O7)·2H2O: acid pyrophosphate metallates(II) with layer structures

The crystal structures of the isomorphous title compounds, namely potassium zinc hydrogen pyrophosphate dihydrate and potassium manganese hydrogen pyrophosphate dihydrate, consist of acidic pyrophosphate–metallate(II) layers joined by K⁺ ions and hydrogen‐bridging bonds. The Zn²⁺/Mn²⁺ ions are octahedrally surrounded by four pyrophosphate O atoms and by two water mol­ecules. The (HP₂O₇)^3? anions exhibit eclipsed conformations. The metal ions and water O atoms lie on mirror planes, as does the central O atom of the (HP₂O₇)^3? anion.     

The molecular and crystal structure of N-(4-n-butyloxybenzylidene)-4'-ethylaniline (4O.2) and N-(4-n-heptyloxybenzylidene)-4'-hexylaniline (7O.6)

757047134     

Correlation between structures and thermal properties of hydrated thallium(I) diborates; H2O-Tl2B4O7 phase diagram

Two synthetic hydrated thallium (I) diborates have been found in the liquidsolid equilibria of the 100° isotherm of the ternary system H₂O-B₂O₃-Tl₂O; they were characterized via the powder diagrams, but classical chemical analysis does not lead to the correct degree of hydration. Through TG of the powders, a complex process is found with no explanation. Structural resolution and TG of the monocrystals allow a correct explanation of the thermal dehydration: these thallium (I) diborates are two distinct compounds, Tl₂B₄O₇ · 3H₂O and Tl₂B₄O₇ · 1.5H₂O, which have their own process of dehydration; they contain infinite chains of polyanions and their structural formulae are Tl₂[B₄O₆ (OH)₂] · 2H₂O and Tl₄[B₈O₁₂ (OH)₄]H₂O; the latter polyanion may be considered as the dimer of the first.The H₂O-Tl₂B₄O₇ phase diagram was established by thermal analysis and solubility experiments, both under pressure; it allows the prediction that another hydrated thallium (I) diborate, Tl₂B₄O₇·H₂O, exists, with possible structural formula Tl₆[B₁₂O₁₈ (OH)₆]. Actually, only monocrystals of Tl₄[B₈O₁₂ (OH)₄]·H₂O have been obtained hydrothermally from Tl₂[B₄O₆ (OH)₂] · 2H₂O.

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Zusammenfassung Im ternären System H₂O-B₂O₃-Tl₂O liegen bei 100° bei Einstellung des Gleichgewichtes flüssig-fest zwei hydratisierte Thallium (I) -diborate vor; diese wurden durch Pulverdiagramme charakterisiert, die klassische chemische Analyse ergab jedoch nicht den richtigen Hydratationsgrad. Bei TGA von Pulvern verläuft ein komplexer Prozeß, für den keine mögliche Erklärung gegeben werden kann. Strukturaufklärung und TGA mit Einkristallen ermöglichen eine korrekte Erklärung der thermischen Dehydratisierung: die hydratisierten Thallium (I) -diborate sind zwei verschiedene Verbindungen der Zusammensetzung Tl₂B₄O₇· 3H₂O und Tl₂B₄O₇· 1.5H₂O mit unterschiedlichem Dehydratisierungsverlauf, die Polyanionketten enthalten und durch die Strukturformeln Tl₂[B₄O₆ (OH)₂] · 2H₂O bzw. Tl₄[B₈O₁₂ (OH)₄] · H₂O zu beschreiben sind. Das Polyanion der zweiten Verbindung kann als Dimeres des der ersten angesehen werden. Das Phasendiagram H₂O-Tl₂B₄O₇ wurde durch unter Druck ausgeführte thermische Analyse und Löslichkeitsexperimente aufgestellt. Aus diesem Phasendiagramm kann die Existenz eines anderen hydratisierten Thallium (I) -diborats, Tl₂B₄O₇ · H₂O, mit der möglichen Strukturformel Tl₆[B₁₂O₁₈ (OH)₆] vorausgesagt werden. In Wirklichkeit wurden aber nur Einkristalle von Tl₄[B₈O₁₂ (OH)₄]·H₂O durch hydrothermale Behandlung von Tl₂[B₄O₆ (OH)₂] · 2H₂O erhalten.

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₂-₂₃-l₂ 100° , . , . : l₂₄₇·₂ l₂₄₇·1.5₂, . l₂[₄₆()₂]· 2₂ l₄[₈₁₂()₄]·₂. . ₂-l₂₄₇. , l₂₄₇·₂ l₆[₁₂₁₈()₆]. , l₄[₈₁₂()₄]·₂ l₂[₄O₆()₂]·2₂O.

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Paper presented at the World Conference on Thermal Analysis Amsterdam, 1984.     

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).     

New metal iodates: syntheses, structures, and characterizations of noncentrosymmetric La(IO3)3 and NaYI4O12 and Centrosymmetric beta-Cs2I4O11 and Rb2I6O15(OH)2.H2O

Four new metal iodates, beta-Cs2I4O11, Rb2I6O15(OH)2.H2O, La(IO3)3, and NaYI4O12, have been synthesized hydrothermally, and the structures were determined by single-crystal X-ray diffraction techniques. All of the reported materials contain I5+ cations that are in asymmetric coordination environments attributable to their stereoactive lone pair. Second-order nonlinear optical measurements on noncentrosymmetric La(IO3)3 and NaYI4O12, using 1064-nm radiation, indicate that both materials have second-harmonic-generating properties with efficiencies of approximately 400xSiO2. Converse piezoelectric measurements revealed d33 values of 5 and 138 pm V-1 for La(IO3)3 and NaYI4O12, respectively. Infrared and Raman spectroscopy and thermogravimetric analyses are also presented for all of the reported materials. Crystal data: beta-Cs2I4O11, monoclinic, space group P2(1)/n (No. 14), with a=12.7662(14) A, b=7.4598(8) A, c=14.4044(16) A, beta=106.993(2) degrees, V=1311.9(2) A3, and Z=4; Rb2I6O15(OH)2.H2O, triclinic, space group P (No. 2), with a=7.0652(17) A, b=7.5066(18) A, c=18.262(4) A, alpha=79.679(4) degrees, beta=85.185(4) degrees, gamma=70.684(4) degrees, V=898.9(4) A3, and Z=2; La(IO3)3, monoclinic, space group Cc (No. 9), with a=12.526(2) A, b=7.0939(9) A, c=27.823(4) A, beta=101.975(4) degrees, V=2418.4(6) A3, and Z=4; NaYI4O12, monoclinic, space group Cc (No. 9), with a=31.235(3) A, b=5.5679(5) A, c=12.5451(12) A, beta=91.120(3) degrees, V=2181.3(4) A3, and Z=4.     

Synthesis and characterization of fluorinated metal arsenates with a layer structure: (C4H12N2)(1.5)[M3F5(HAsO4)2(AsO4)] (M = Fe, Ga)

Two fluorinated metal arsenates, (C(4)H(12)N(2))(1.5)[M(3)F(5)(HAsO(4))(2)(AsO(4))] (M = Fe, Ga), have been synthesized under hydrothermal conditions and characterized by single-crystal X-ray diffraction, magnetic susceptibility, M?ssbauer spectroscopy, and (71)Ga NMR spectroscopy. The two compounds are isostructural and crystallize in the monoclinic space group P2(1)/c (No. 14) with a = 8.394(1) A, b = 21.992(3) A, c = 10.847(1) A, beta = 96.188(2) degrees, and Z = 4 for the Fe compound, and a = 8.398(1) A, b = 21.730(3) A, c = 10.679(1) A, beta = 95.318(2) degrees, and Z = 4 for the Ga compound. The structure consists of infinite chains of corner-sharing MX(6) (X = O, F) octahedra and dimers of edge-sharing MO(3)F(3) octahedra, which are linked into two-dimensional sheets through arsenate tetrahedra with diprotonated piperazinium cations between the sheets. Magnetic susceptibility and M?ssbauer spectroscopy confirm the presence of Fe(III). The (71)Ga MAS NMR spectrum clearly shows a line shape consisting of three components, corresponding to three crystallographically distinct Ga sites.     

ChemInform Abstract: Preparation and Crystal Structures of the Vanadiumphosphates VPO4. times.2 H2O (I) and V5.12(PO4)4(OH)3.36(H2O)0.64×0.84 H2O (II).

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.     

Vapor Phase Vibrational Spectra for Re(2)O(7) and the Infrared Spectrum of Gaseous HReO(4). Molecular Shapes of Mn(2)O(7), Tc(2)O(7), and Re(2)O(7)

The Raman and infrared spectra of gas phase Re(2)O(7) are reported. The experimental vibrational spectra of molecular Tc(2)O(7) and Re(2)O(7) are compared with calculated spectra. The results of these studies agree with a nonlinear M-O-M bridge for Tc(2)O(7) and Re(2)O(7). For infrared intensity calculations, the point charge approximation is used, while for the Raman calculations a combination of bond and atom polarizabilities is adopted. Pure Re(2)O(7) was prepared from rhenium wire, but attempts to prepare it from rhenium powder and oxygen always led to infrared spectra showing serious contamination from a species containing an -OH linkage. Detailed experiments identified this molecule as HReO(4), a unique transition metal analogue of the perhalic acids, and a partial infrared spectrum of this molecule is reported.     

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.     

Two caesium vanadium hydrogenphosphates with tunnelled structures: Cs2V2O3(PO4)(HPO4) and Cs2[(VO)3(HPO4)4(H2O)]·H2O

Dicaesium divanadium trioxide phosphate hydrogenphosphate, Cs₂V₂O₃(PO₄)(HPO₄), (I), and dicaesium tris[oxidovanadate(IV)] hydrogenphosphate dihydrate, Cs₂[(VO)₃(HPO₄)₄(H₂O)]·H₂O, (II), crystallize in the monoclinic system with all atoms in general positions. The structures of the two compounds are built up from VO₆ octahedra and PO₄ tetrahedra. In (I), infinite chains of corner‐sharing VO₆ octahedra are connected to V₂O₁₀ dimers by phosphate and hydrogenphosphate groups, while in (II) three vanadium octahedra share vertices leading to V₃O₁₅(H₂O) trimers separated by hydrogenphosphate groups. Both structures show three‐dimensional frameworks with tunnels in which Cs⁺ cations are located.     

Crystal structure of (C2H7N4O)2[UO2(C2O4)2(H2O)]

The single crystals of (C₂H₇N₄O)₂[UO₂(C₂O₄)₂(H₂O)] were studied by X-ray diffraction. The crystals are monoclinic, space group Pn, Z = 2, unit cell parameters: a = 9.4123(2) Å, b = 8.4591(2) Å, c = 11.8740(3) Å, β = 105.500(10)°, V = 911.02(4) ų. The main structural units of the crystals of I are islet complex groups [UO₂(C₂O₄)₂(H₂O)]^2? corresponding to the crystal chemical group AB ₂ ⁰¹ M¹ (A = UO UO ₂ ²⁺ , B⁰¹ = C₂O ₄ ^2? , M = H₂O) of uranyl complexes. Uranium-containing mononuclear complexes are connected into a three-dimensional framework through the electrostatic interactions and hydrogen bonding system involving carbamyolguanidinium ions.