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.     

Crystallographic report: Dimethyl‐2‐phenylethan‐2‐olamine cyanoborane

The structure of the title compound reveals the geometry around the boron atom to be tetrahedral, and the B? C?N moiety has a bent geometry. Copyright © 2005 John Wiley & Sons, Ltd.     

Über Oxorhodate der Alkalimetalle: β-LiRhO2

On Oxorhodates of Alkali Metals: β-LiRhO₂ We prepared hitherto unknown β-LiRhO₂ in form of black, cubic single crystals, O⁴–F4₁32, a = 841.27(6) pm, Z = 16. For a first time in case of such metal oxides we find one of the possible variants of order between the NaCl-type with random distribution and the complete ordered types like α-NaFeO₂ as a single crystal (four-circle-diffractometer PW 1100, AgKα, 100 von 109 I₀(hkl), R = 9.10%, R_w = 5.46%). The Madelung Part of Lattice Energy, MAPLE, and Effective Coordination Numbers, ECoN, these via Mean Fictive Ionic Radii, MEFIR, were calculated and discussed.     

Unprecedented μ-η2:η2-Pyrazolate Coordination in [{Yb(η2-tBu2pz)(μ-η2:η2-tBu2pz)(thf)}2]

A higher degree of coordination saturation is attainable through the unusual coordination mode in the title compound 1 , in which the central pyrazolate groups function both as chelating and as bridging ligands. There is some asymmetry in the bridging, and the N atoms of each μ-η²:η²-pyrazolato ligand are 0.07–0.11 Å closer to one of the two Yb centers.     

Kristallstrukturen aus CaBe2Ge2‐ und CeMg2Si2‐analogen Blöcken: Die Phosphide LnPt2P2−x (Ln: La,Sm)

Crystal Structures of CaBe₂Ge₂ and CeMg₂Si₂ analogous Units: The Phosphides LnPt₂P_2?x (Ln: La, Sm) Single crystals of LaPt₂P_1.44 (a = 4.174(1), c = 19.212(5) Å) were grown by reaction of vaporous phosphorus with LaPt₂ at 1050 °C during two weeks, whereas SmPt₂P_1.50 (a = 4.131(1), c = 19.086(4) Å) was synthesized by heating mixtures of the elements at 900 and 1100 °C (60 h) and annealing at 1050 °C (300 h). Both phosphides were investigated by single crystal X‐ray methods. Their crystal structures (I4/mmm; Z = 4) consist of CaBe₂Ge₂ and CeMg₂Si₂ analogous units alternating with each other along [001]. The positions of the P1 atoms are occupied incompletely causing the deviation to the 1:2:2 stoichiometry. Another compounds LnPt₂P_2?x were studied by X‐ray powder diffraction resulting in the following lattice constants: a = 4.150(1), c = 19.132(5) Å for CePt₂P_2–x, a = 4.137(1), c = 19.085(4) Å for PrPt₂P_2?x, and a = 4.127(1), c = 19.040(2) Å for NdPt₂P_2?x.     

Binary ZrO<Subscript>2</Subscript>-SiO<Subscript>2</Subscript> xerogels: Synthesis and properties

Binary systems of silica and zirconia xerogels have been prepared by hydrolysis of zirconium(IV) oxychloride in the silica gel matrix. Systems of various composition have been studied by ¹H NMR, IR spectroscopy, and thermogravimetry and have been tested in a model process of hydrogen peroxide decomposition. It has been shown that the physicochemical properties of binary oxide systems can be tailored by varying the component ratio.     

TiO<Subscript>2</Subscript>-SiO<Subscript>2</Subscript> binary xerogels: Synthesis and characterization

Silica/titania binary xerogels were prepared by joint hydrolysis of the ingredients. Gels of various compositions were characterized by ¹H NMR spectroscopy, IR spectroscopy, and thermogravimetry. The spectral characteristics of binary systems differ considerably from mere superposition of the spectra of the two constituent compounds and the spectrum of a mechanical mixture. A feasibility was demonstrated for controlling the acid properties of binary oxide gels via varying the component mole ratio.     

PbO<Subscript>2</Subscript>-TiO<Subscript>2</Subscript> composites: Electrosynthesis and physicochemical properties

Fundamental aspects of electro deposition of PbO₂-based composites containing titanium dioxide particles were studied. The content of the dispersed phase in the composite depends on the electrolyte composition and deposition conditions. Incorporation of titanium dioxide particles into PbO₂ leads to significant changes in the morphology and structure of the deposit.     

2‐Azido‐2‐deoxycellulose: Synthesis and 1,3‐Dipolar Cycloaddition

Chitosan ( 1 ) was prepared by basic hydrolysis of chitin of an average molecular weight of 70000 Da, ¹H‐NMR spectra indicating almost complete deacetylation. N‐Phthaloylation of 1 yielded the known N‐phthaloylchitosan ( 2 ), which was tritylated to provide 3a and methoxytritylated to 3b . Dephthaloylation of 3a with NH₂NH₂?H₂O gave the 6‐O‐tritylated chitosan 4a . Similarly, 3b gave the 6‐O‐methoxytritylated 4b . CuSO₄‐Catalyzed diazo transfer to 4a yielded 95% of the azide 5a , and uncatalyzed diazo transfer to 4b gave 82% of azide 5b . Further treatment of 5a with CuSO₄ produced 2‐azido‐2‐deoxycellulose ( 7 ). Demethoxytritylation of 5b in HCOOH gave 2‐azido‐2‐deoxy‐3,6‐di‐O‐formylcellulose ( 6 ), which was deformylated to 7 . The 1,3‐dipolar cycloaddition of 7 to a range of phenyl‐, (phenyl)alkyl‐, and alkyl‐monosubstituted alkynes in DMSO in the presence of CuI gave the 1,2,3‐triazoles 8 – 15 in high yields.     

2-hydroxypyridine <--> 2-pyridone tautomerization: catalytic influence of formic acid

A 1:1 hydrogen-bonded complex between 2-pyridone and formic acid has been characterized using laser-induced-fluorescence excitation and dispersed fluorescence spectroscopy in a supersonic jet expansion. Under the same expansion condition, the fluorescence signal of the tautomeric form of the complex (2-hydroxypyridine...formic acid) is absent, although both the bare tautomeric molecules exhibit well-resolved laser-induced-fluorescence spectra. Quantum chemistry calculation at the DFT/B3LYP/6-311++G** level predicts that in the ground electronic state the activation barrier for tautomerization from hydroxy to keto form in bare molecules is very large (approximately 34 kcal/mol). However, the process turns out to be nearly barrierless when assisted by formic acid, and double proton transfer occurs via a concerted mechanism.     

Tetrakis(μ‐benzothiazole‐2‐thiolato)‐1:2κ4N:S2;1:2κ4S2:N‐dichloro‐1κCl,2κCl‐dirhenium(III)(Re—Re) dichloromethane solvate: a bridged complex with a long Re—Re quadruple bond

The title compound, [Re₂(C₇H₄NS₂)₄Cl₂]·CH₂Cl₂, consists of dirhenium mol­ecules with bridging N,S‐benzo­thia­zole‐2‐thiol­ate ligands, axial Cl^? ligands and intramolecular hydrogen bonding. These mol­ecules adopt somewhat staggered conformations, with a long Re—Re quadruple bond distance of 2.2716 (3) Å.     

Notiz über den α-LiFeO2-Typ: NaPrO2 und NaTbO2

On the α-LiFeO₂ Type of Structure: NaPrO₂ and NaTbO₂ For the first time transparent light-green single crystals of NaPrO₂ [from PrO_1,833: KO_0,50:NaO_0,50 = 1:1.1:1.2 Ni-cylinder, 1000°C, 20 d] and colourless single crystals of hitherto unknown NaTbO₂ [from Na₂TbO₃, Ni-cylinder, 1000°C, 10 d] have been prepared and investigated by X-ray. The tetragonal α-LiFeO₂-type is confirmed. [NaPrO₂: a = 476.19(3), c = 1096.09(11) pm, c/a = 2.30; 107 I₀ (hkl); R = 4.25% R_w = 3.39%, MoKα; NaTbO₂: a = 463.11(3), c = 1037.39(12) pm, c/a = 2.24; 103 I₀ (hkl); R = 3.54%; R_w = 2,81%; MoKα; both space group I4₁/a m d; fourcircle diffractometer Philips PW 1100]. The Madelung Part of Lattice Energy, MAPLE, and the peculiarities of this type of structure are discussed.     

μ‐Acetato‐1:2κ2O:O′‐diacetato‐1κ2O,O′;2κO‐bis(di‐2‐pyridylamine)‐1κ2N,N′;2κ2N,N′‐isothiocyanato‐2κN‐dicopper(II)

In the title dinuclear acetate‐bridged complex, [Cu₂(C₂H₃O₂)₃(NCS)(C₁₀H₉N₃)₂], the two Cu atoms are five‐coordinated, with a basal plane consisting of two N atoms of a di‐2‐pyridylamine (dpyam) ligand and two O atoms of two different acetate ligands. The axial positions of these Cu atoms are coordinated to N and O atoms from thio­cyanate and acetate mol­ecules, respectively, leading to a distorted square‐pyramidal geometry with τ values of 0.30 and 0.22. Both Cu^II ions are linked by an acetate group in the equatorial–equatorial positions and have syn–anti bridging configurations. Hydrogen‐bond inter­actions between the amine H atom and the coordinated and uncoordinated O atoms of the acetate anions generate an infinite one‐dimensional chain.     

Über Oxocadmate: K2Cd2O3

New obtained is K₂Cd₂O₃ (brownish red), which – according to single crystal work [487 h 01–h 41, Mo? Kα, R = 9.7₃%, R′ = 10.7₆%] – crystallises monoclinic with a = 6.41₇, b = 6.72₃, c = 6.58₆ Å, β = 116.0° in P2₁/c–C [K⁺, Cd²⁺ and O(1)^2? in 4(e), O(2)^2? in 2(a)] and is isotypic with Na₂Zn₂O₃. [Parameters see text]. The Madelung Part of Lattice Energy is calculated and discussed.