Die Kristallstruktur von TlFe3Te3

TlFe₃Te₃ is hexagonal, space groupP6₃/m–C _2h ⁶ ,a=9.350(2) Å,c=4.2230 (7) Å,Z=2. Iron and tellurium atoms occupy the positions 6 (h) withx=0.170,y=0.149 andx=0.046,y=0.357 respectively. Thallium atoms are situated in 2 (d). The structure was determined on the basis of single crystal data obtained form a four circle diffractometer. Refinement yielded andR-value of 4.8% for an asymmetric set of 267 reflections. TlFe₃Te₃ is a new structure type. The structure and its relations to the Mn₅Si_3–, the Nb₃Te₄-and the Tl _x V₆S₈-type are discussed.

     

Komplexe des zweiwertigen Molybdäns,Derivate des Oktahalodimolybdat(II)-Ions, 4. Mitt.: Darstellungen und Kristallstrukturen von zwei neutralen Komplexen mit 4-Methylpyridin

Mo₂Cl₄ Pic ₄·CHCl₃ (A) (Pic=4-methylpyridine) and Mo₂Br₄ Pic ₄ (B) crystallize in the monoclinic space group.A inC2/c (No. 15) witha=15.175 (4),b=10.847 (2),c=19.946 (6) and =104.52 (2)°;D _o=1.71 (2),D _c =1.72 gcm^–3 forZ=4.B inP2_l/n (No. 14) witha=9.270 (3),b=16.614 (5),c=9.305 (3) and =91.96 (5)°;D _o=2.03 (3),D _c =2.05 gcm^–3 forZ=2.Two halogens and 4-methylpyridines of the MoX ₂ Pic ₂ group are in the trans position. Mo–Mo bond lengths are 2.153 96) forA and 2.150 92) forB. Both molecules are situated on the inversion center resulting in the eclipsed configuration of the ligands around the molybdenum pair. The structure ofB has been refined to the conventionalR factors of 0.08 and 0.098. Disorder on the part of 4-methylpyridines and chloroform molecules stopped the refinement ofA at the endR value of 0.175.Mean Mo–X and Mo–N bonding distances are 2.40 (2), 2.25 (5) forA and 2.53 (3), 2.25 (1) forB.

     

Chemical applications of topology and group theory

The 60 even permutations of the ligands in the five-coordinate complexes, ML ₅, form the alternating group A ₅, which is isomorphic with the icosahedral pure rotation group I. Using this idea, it is shown how a regular icosahedron can be used as a topological representation for isomerizations of the five-coordinate complexes, ML ₅, involving only even permutations if the five ligands L correspond either to the five nested octahedra with vertices located at the midpoints of the 30 edges of the icosahedron or to the five regular tetrahedra with vertices located at the midpoints of the 20 faces of the icosahedron. However, the 120 total permutations of the ligands in five-coordinate complexes ML ₅ cannot be analogously represented by operations in the full icosahedral point group I _h, since I _his the direct product I×C₂ whereas the symmetric group S ₅ is only the semi-direct product A ₅S₂. In connection with previously used topological representations on isomerism in five-coordinate complexes, it is noted that the automorphism groups of the Petersen graph and the Desargues-Levi graph are isomorphic to the symmetric group S ₅ and to the direct product S ₅×S ₂, respectively. Applications to various fields of chemistry are briefly outlined.     

207Pb-NMR-Untersuchungen an Bleiorganylen

The high-resolution²⁰⁷Pb magnetic resonance spectra ofR _4–n PbX _n (R=Methyl, Ethyl;X=h₁-Cyclopentadienyl, Chloride;n=1, 2) have been studied at 16.72Mc. The²⁰⁷Pb- ·· -¹H spin-spin coupling constants for the molecules described have been obtained by analysis of the first order NMR-patterns as A_xB_yM and A_xB_yC_zM respectively. The experimental spectra have been verified by a computer simulation. The chemical shifts and coupling constants of the lead organyls investigated show similar dependences on moleculare structure as well as number and species of the substituents like analogous organotin compounds.

     

Theory of spin triplet ground states ind 6 transition metal compounds and the effect of high-energy states on the nature of the ground state

The formation of spin triplet, quintet, and singlet ground states within the 3d ⁶ electron configuration is investigated inD _4h , andD _3d symmetries employing irreducible tensor operator methods. Significant differences in the possible ground states are encountered between a complete CI and spin-orbit interaction treatment and an approximate calculation within the cubic⁵ T ₂,¹A₁,³ T ₁, and³ T ₂ parents.     

Über Erdalkalimetalloxogallate. VIII Synthese und Aufbau eines neuen Calciumoxogallats: Ca3Ga4O9

The hitherto unknown compound Ca₃Ga₄O₉ was prepared and investigated by X-ray single crystal methods. Ca₃Ga₄O₉ has orthorhombic symmetry:a=1435.8;b=1682.5;c=532.1 pm; space group C _2v ¹¹ –Cmm2,Z=6. The tetrahedra network (circles of 4 and 5 GaO₄-tetrahedra) and the surrounding of Ca²⁺ are described and discussed with respect to other oxogallates.

     

Die Kristallstruktur der isotypen Verbindungen KAg(NO3)2, NH4Ag(NO3)2 und RbAg(NO3)2

KAg(NO₃)₂ crystallizes in space group P2₁/a-C _2h ⁵ ,a=13.953,b=4.955,c=8.220 Å, =97.76°,Z=4. X-ray intensities were collected with a two-circle diffractometer. The structure was solved by means of direct methods andFourier syntheses and was refined by the least squares method toR=0.034 with 1346 observed reflexions. ¹ {Ag₂(NO₃)₄}^2–-chains run parallel toy and are linked by potassium ions. Ag shows a distorted tetrahedral coordination with four relatively close O. K is irregularily surrounded by ten O. The isotypic compounds NH₄Ag(NO₃)₂ and RbAg(NO₃)₂ were refined toR=0.032 and 0.035, respectively. The coordination figures are compareable with those in KAg(NO₃)₂.

     

The (E)/(Z)-ratio in the reaction of 5-(2-aryl-2-oxoethyl)-2-thioxo-4-oxo-1,3-thiazolidines with bromine

Summary 3-Aryl-, 3-benzyl-, and 3H-5-(2-aryl-2-oxoethyl)-2-thioxo-4-oxo-1,3-thiazolidines3a–h react with bromine in acetic acid solution to give mixtures of the respective 5-aroylmethylene (E) and (Z) diastereomeric derivatives5 and6. They contain more than 85% of the (E)-diastereomers along with some pure isomers. The intermediacy of the 5-bromo derivatives4 is proven and a plausible route of the reaction is presented. Structures of compounds3–6 are evidenced by analytical and spectral data.

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Das Verhältnis von (E)- und (Z)-Isomeren bei der Reaktion von 5-(2-Aryl-2-oxomethyl)-2-thioxo-4-oxo-1,3-thiazolidinen mit Brom

Zusammenfassung 3-Aryl-, 3-Benzyl- und 3H-5-(2-Aryl-2-oxoethyl)-2-thioxo-4-oxo-1,3-thiazolidine3a–h reagieren mit Brom in essigsaurer Lösung zu Gemischen der entsprechenden diastereomeren 5-Arylmethylen-Derivate ((E) und (Z))5 und6. Sie enthalten mehr als 85% des (E)-Diastereomeren. Die intermediäre Natur der 5-Brom-Derivate4 wird bewiesen; ein Reaktionsweg wird vorgeschlagen. Die Strukturen der Verbindungen3–6 werden durch analytische und spektroskopische Daten abgesichert.

     

Comparative study of structural stability in [NH4−n (CH3) n ]2HgCl4 and in related compounds

The structural instability of the [NH_4−n (CH₃) _n ]₂HgCl₄ group has been investigated. Consideration of different crystals of this family shows that the H-bonds, obviously, hinder the appearance of incommensurate modulation. The dependence of phase transition sequence on the sizes of cation and anion may be obtained only for crystals with simple cation. The appearance of H-bonds complicates the situation and, leads to gradual disappearance of IC phase in the A₂BX₄ family.     

Die Kristallstruktur von Ca2As2O7

The structure of Ca₂As₂O₇ (a ₀=7.05,b ₀=9.30,c ₀=4.89 Å; =101.3°; space groupC2/m-C _2h ³ ;Z=2) has been solved from 465 independent X-ray intensities collected on aWeissenberg-type diffractometer up to anR-factor of 2.4% for all intensities. The structure of Ca₂As₂O₇ represents a further Thortveitite structure type.

     

The group-theoretical structure of the atomic g shell: connection with the alternating group <Emphasis Type="Italic">A</Emphasis><Subscript>6</Subscript> as <Emphasis Type="Italic">L</Emphasis><Subscript>2</Subscript>(9)

The special projective linear groups PSL(2ℓ + 1) or L ₂(2ℓ + 1) of order 2ℓ(2ℓ + 1)(ℓ + 1) can be used to study atomic shells of electrons with angular momentum quantum number ℓ corresponding to the atomic p, d, f, and g shells for ℓ = 1, 2, 3, 4, respectively. For the atomic g shell the group L ₂(9) is isomorphic with the alternating group A ₆ on six objects of order 360 or the symmetry group of the 5-dimensional simplex, a 5-dimensional analogue of the tetrahedron with 6 vertices and 15 edges. This leads to the subgroup chain SO(9) ⊃ SO(5) ⊃ L ₂(9) for the atomic g shell analogous to the subgroup chain SO(7) ⊃ G ₂ ⊃ L ₂(7) ≈⁷ O for the atomic f shell. In the L ₂(9) group only the representations of spherical harmonics or sums thereof, Γ(Y_ℓ), with dimensions dim Γ(Y_ℓ) or dim Γ(Y_ℓ) ± 1 divisible by 9 are found to be individually reducible to irreducible representations (irreps) or sums of irreps of L ₂(9). This leads to term groupings such as S, PD, G, PF, DH, L, PK, DI, FH, M, FI, PO, DN, HK, R, etc., of increasing total dimension for the irreps of SO(9) for various g ⁿ configurations in the atomic g shell.     

Die Kristallstruktur von TlFeSe2 und TlFeS2

TlFeSe₂ is monoclinic, space groupC2/m–C _2h ³ ,a=11.973 Å,b=5.490 Å,c=7.110 Å, =118.2°,Z=4.TlFeS₂ is isotypic witha=11.636 Å,b=5.304 Å,c=6.799 Å, =116.7°.The crystal structure of TlFeSe₂ has been determined from single crystal diffractometer data. Isotypy of the sulfide has been confirmed from powder diffraction data. The crystal structure containing infinite linear chains of edgesharing FeX ₄-tetrahedra, and its relationship to the thio- and selenoferrates of the alkali metals are discussed. The mineral raguinite is very probably isotypic to synthetic TlFeS₂.

     

A One-Pot Synthesis and Structure Determination of 3-(1-Phenyl-5-p-tolylpyrazol-3-yl)-2-p-tolylindole Ethanol Solvate

The Fischer indolization afforded the title compound C₃₁H₂₅N₃·C₂H₅OH as the major product in the reaction of 1,5-di(p-tolyl)pentane-1,3,5-trione with phenylhydrazine hydrochloride in ethanol. The structure assignment of this novel pyrazolylindole derivative is based on the data of elemental analysis, IR, ¹H NMR, and ¹³C NMR spectroscopy. The structure is also confirmed by means of X-ray crystallography. The molecule crystallizes in the orthorhombic space group P 2₁2₁2₁, with a = 10.298(2), b = 14.984(5), c = 18.133(3) A, Z = 8, V = 2798.0(12) A³. The absolute structure has been determined. The ethanol molecule forms intermolecular hydrogen bonds with the pyrazole and indole nitrogen atoms.     

Ein Beitrag zur Kristallchemie der Kobaltoxoniobate: CoNb2O6 mit Rutilstruktur

CoNb₂O₆ can be prepared by reaction of stoichiometric amounts of CoO (thermical decomposition of cobaltoxalate) and Nb₂O₅ in argon-atmosphere up to 1,400 °C. The isolated red-brown single crystals have tetragonal symmetry (a=472.6;c=305.4 pm; space group P4₂/mnm-D _4h ¹⁴ ). Electron probe micro-analysis of the single crystals verifies the composition Co_0.33Nb_0.67O₂. Co²⁺ and Nb⁵⁺ occupy statistically the metal positions of the rutil-type structure. The differences between Co_0.5Nb_0.5O₂ (CoNbO₄AlNbO₄-type) and Co_0.38Nb_0.67O₂ (CoNb₂O₆) are discussed.

     

Fermi resonance in substitutedZ-3-methylene phthalides

Summary The absorption bands of the C=O Stretching vibrations of a series of thirty-nine substitutedZ-3-methylene phthalides (1a-s, 2a-h, 3a-f, 4a-c, and5a-c) were measured in CHCl₃ and CCl₄. The two-levelFermi resonance effect on the infrared spectra of the above compounds was investigated after deconvolution and band separation. The wave numbers of the unperturbed fundamental C=O stretching vibrations exhibit excellent linear correlations withHammet's constants of substituents and¹³C NMR chemical shifts of the C=O group.

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Fermi-Resonanz in substituiertenZ-3-Methylenphthaliden

Zusammenfassung Die Absorptionsbanden der C=O-Streckschwingung von 39 substituiertenZ-3-Methylenphthaliden (1a-s, 2a-h, 3a-f, 4a-c und5a-c) wurden in CHCl₃ und CCl₄ vermessen. Durch Dekonvolution und Bandentrennung konnte der EinflußFermi-Resonanz auf die Infrarotspektren der obengenannten Verbindungen untersucht werden. Die Wellenzahlen der ungestörten C=O-Streckschwingungen ergeben ausgezeichnete lineare Korrelationen mit denHammetschen Substituentenkonstanten und den¹³C-NMR-Verschiebungen der Carbonylgruppe.

     

LiLa6I12Os, a substitutional derivative of rhombohedral La(La6I12Os)

The series of quaternary rare-earth-metal halide cluster compounds ALa₆I₁₂Z with transition metal interstitials Z and alkali or alkaline-earth metal cations A has been expanded to include A=Li. The compounds synthesized by high-temperature solid-state techniques for Z=Os, Ir, Pt, Ru are isotypic with rhombohedral R₇X₁₂Z (, Z=3). The refined single X-ray crystal structure of (Li_0.967La_0.033)La₆I₁₂Os is reported, along with supportive results from a Rietveld analysis of neutron powder diffraction from a different sample, ⁷Li MAS-NMR, and electronic resistivity and magnetic susceptibility measurements. The samples show continuous Li_1−xLa_x cation compositions and are generally semiconductors, but their complex paramagnetic properties are not those of simple spin-only systems.     

Synthesis and crystal structure of 1-ethyl-3-(phenyl)-1,2,3-triazolium percholorate

The isolation of stable carbenes of the Arduengo (1a) and Wanzlick (2a) type has prompted us to look for stable nitrenium ions of the related structural type 1-ethyl-3-(phenyl)-1,2,3-triazolium perchlorate (6⁺). The title compound C₁₀H₁₄Cl N₃O₄ was isolated and structure was investigated by X-ray crystallography. It crystallizes in the monoclinic space group P2₁/c with cell parameters a=6.697(4) Å, b=9.724(9) Å, c=19.844(2) Å and Z=4. The final residual factor is R1=0.0471 for 1545 reflections with I>2σ(I). The structure exhibits intermolecular hydrogen bonds.     

Röntgenstrukturanalyse des Methyl-5-acetylamino-7,8-anhydro-4,9-bis-O-(t-butyldimethylsilyl)-3,5-didesoxy-L-glycero-β-D-galakto-2-nonulopyranosidon-säuremethylesters

An X-ray crystal structure analysis of the title compound was carried out at –168°C in order to assign the stereochemistry around the oxirane: C₂₅H₄₉NO₈Si₂, trigonal, R3,a=25.18(1),c=13.55(1) Å (hexagonal axes),Z=9,d _x =1.105.The structure was solved with direct methods and refined to anR-factor of 0.086.

     

Methyl 2‐acetamido‐2‐deoxy‐β‐d‐glucopyranoside dihydrate and methyl 2‐formamido‐2‐deoxy‐β‐d‐glucopyranoside

Methyl 2‐acetamido‐2‐deoxy‐β‐d ‐glucopyranoside (β‐GlcNAcOCH₃), (I), crystallizes from water as a dihydrate, C₉H₁₇NO₆·H₂O, containing two independent molecules [denoted (IA) and (IB)] in the asymmetric unit, whereas the crystal structure of methyl 2‐formamido‐2‐deoxy‐β‐d ‐glucopyranoside (β‐GlcNFmOCH₃), (II), C₈H₁₅NO₆, also obtained from water, is devoid of solvent water molecules. The two molecules of (I) assume distorted ⁴C₁ chair conformations. Values of ϕ for (IA) and (IB) indicate ring distortions towards B_C2,C5 and ^C3,O5B, respectively. By comparison, (II) shows considerably more ring distortion than molecules (IA) and (IB), despite the less bulky N‐acyl side chain. Distortion towards B_C2,C5 was observed for (II), similar to the findings for (IA). The amide bond conformation in each of (IA), (IB) and (II) is trans, and the conformation about the C—N bond is anti (C—H is approximately anti to N—H), although the conformation about the latter bond within this group varies by ∼16°. The conformation of the exocyclic hydroxymethyl group was found to be gt in each of (IA), (IB) and (II). Comparison of the X‐ray structures of (I) and (II) with those of other GlcNAc mono‐ and disaccharides shows that GlcNAc aldohexopyranosyl rings can be distorted over a wide range of geometries in the solid state.