Isomerisierung und Ringinversion von Tribenzaspiro[5.5]undecaphanen

For the two possible ring inversions in tribenzaspiro[5.5]undecaphanes—corresponding to the isomerizations79 and97 resp.—no mutual influence is found. Thus the degenerate isomerizations (topomerizations)77 and99 can proceedvia two consecutive (non-concerted) reversals. A ring inversion path similar to that for [2.2]metacyclophane (1) is postulated. The considerable ease of the isomerization of9 as compared to1 can be understood on the basis of thermodynamic arguments.Moreover it is confirmed that the free enthalpy difference G ₃₆₀=3.84 kcal/mol of7 and9 at equilibrium originates almost entirely from the different stabilities of boat and chair shaped benzene rings.These conclusions are drawn from a kinetic study of the thermal isomerization of9 and equilibration experiments in comparison with the corresponding data of1. The activation parameters for the process97 are: G _360isom ^A =26.52 kcal/mole, H _isom ^A =25.35 kcal/mole, S _isom ^A =–3.28 cal/deg·mole (isomerization) and G _360inv ^A =27.03 kcal/mole, H _inv ^A =25.35 kcal/mole, S _inv ^A =–4.67 cal/deg·mol (ring reversal); the corresponding data for the degenerate isomerizations of7 and9—identical with those for the ring reversal in7—were deduced to be G _360inv ^B =30.87 kcal/mole, H _inv ^B =27.50 kcal/mole and S _inv ^B =–9.5 cal/deg·mole.

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Mit 7 Abbildungen

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Herrn Prof.H. Nowotny mit besten Wünschen zum 65. Geburtstag gewidmet.

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7. Mitt.:H. Keller, E. Langer undH. Lehner, Mh. Chem.107, 949 (1976).     

Benzofurobenzthiazole: VI—1H- und 13C-NMR-Spektren von 2-Aminobenzofuro[2,3-f] benzthiazol und 2-Aminobenzofuro[2,3-e]benzthiazol im Vergleich mit Dibenzofuran und 2-Aminobenzthiazol

Cyclization of 3-dibenzofurylthiourea under the conditions of the Hugershoff reaction gives the linear structure 1. ¹H n.m.r. and ¹³C n.m.r. spectra of the two isomeric aminobenzofurobenzothiazoles (1 and 3), recorded at 220 MHz, 60 MHz and 22,62 MHz respectively, were used as aids for the structure determination. The magnetic parameters were obtained partly by first-order analysis and partly by simulation of spectra using LAOCOON 3. The assignments were made by comparing the chemical shifts and coupling constants with those of the parent compounds dibenzofuran (4a) and 2-aminobenzothiazole (5c). In so far as the assignments of ¹H n.m.r. and ¹³C n.m.r. frequencies of the parent compounds themselves were unknown or supported by analogy only, they have been determined using experimental criteria such as deuterium substitution and investigation of changes in chemical shifts caused by derivation.     

Darstellung und Schwingungsspektren von Dichloro- und Dibromodithiophosphat Die Kristallstrukturen von [PPh3Me] [PS2Cl2] und [PPh4] [PS2Br2]

Preparation and Vibrational Spectra of Dichloro and Dibromodithiophosphate. Crystal Structures of [PPh₃Me][PS₂Cl₂] and [PPh₄][PS₂Br₂] Dichloro and dibromodithiophosphates [Cat⁺][PS₂X₂^?] with a large organic cation can be obtained from P₄S₁₀, CatX and HX in CH₂Cl₂ (Cat⁺ = PPh₄⁺, PPh₃Me⁺; X = Cl, Br). The vibrational spectra (i.r. and Raman) of the [PS₂X₂]^? ions are reported and discussed; force constants were calculated. The crystal structures of [PPh₃Me][PS₂Cl₂] and [PPh₄][PS₂Br₂] were determined and refined with X-ray diffraction data. In both cases, simple anions [PS₂X₂]^? are present. [PPh₃Me][PS₂Cl₂]: orthorhombic, space group P2₁2₁2₁, a = 1089, b = 1334, c = 1476 pm, Z = 4, refinement to a residual index R = 0.046 for 1116 reflexions; the structure is isotopic with [PPh₃Me][VO₂Cl₂]. [PPh₄][PS₂Br₂]: tetragonal space group I4 , a = 1301, c = 721 pm, Z = 2, refinement to R = 0.065 for 357 reflexions; the structure is isotypic with [AsPh₄][FeCl₄] with [PS₂Br₂]^? ions occupying positions of 4 -symmetry with statistical orientation (statistical superposition of Br and S positions).     

Die Bestimmung geringer Gehalte von Schwefelkohlenstoff im Benzol bzw. im Cyclohexan

Ohne Zusammenfassung     

Synthesen und Untersuchungen von [Oxazolo[2,3-a]isoindol-9b(2H)-yl]phosphonaten und -phosphinaten: Eine neue Klasse von Heterocyclen

Syntheses and Investigations of [Oxazolo[2,3-a]isoindol-9b(2H)-yl]phosphonates and -phosphinates: a New Class of Heterocycles We attempted to synthesize diethyl (1-methyl-2-phthalimidoethyl)phosphonate ( 14a ) in a Michaelis-Becker reaction using diethyl sodiophosphonate ( 13 ) and the tosylate 12a of (2-hydroxypropyl)phthalimide as starting materials. Instead of TsO substitution in 12a by the nucleophile 13 , the carbonyl C-atom of the phthalimido moiety was attacked by 13 , followed by an intramolecular nucleophilic substitution at C(2) of the side chain leading to the (oxazolo[2,3-a]isoindolyl)phosphonate 15a (Scheme 1). Similarly, 12a and N-(2-bromoethyl)phthalimide ( 12b ) reacted with butyl (benzene)sodiophosphinate ( 18 ) to the (oxazolo[2,3-a]isoindolyl)(phenyl)phosphinates 20a and 20b , respectively (Scheme 2). The attempt to synthesize enantiomerically pure 2-substituted (2-phthalimidoethyl)phosphonates 27 starting from L -α-amino-acids failed, too (Scheme 3): the main products of the reaction of the N,N-phthaloyl-O¹-tosyl-L -aminoalcohols 25a–d with 13 were the 3-substituted (oxazolo[2,3-a]isoindolyl)-phosphonates 26a–d , the desired 27b and 27c being observed as by-products in the ³¹P-NMR spectrum.     

Synthese und Struktur von Vinamidinatodiiodalanen [1]

The diiodoalanes (C₅H₇R₂N₂)AlI₂ [ 6 ; R = Me ( a ), Ph ( c )] are obtained from the corresponding alanes (C₅H₇R₂N₂)AlH₂ ( 5 ) and [Me₃NH]I in good yields. (C₅H₇R₂N₂)AlI₂ [ 6 ; R = iso‐Pr ( b )] is alternatively prepared, as well as 6a , from the corresponding vinamidine lithium compound C₅H₇R₂NLi ( 8 ) and AlI₃. (C₅H₇Me₂N₂)AlBr₂ ( 9a ) is formed according to both methods. The X‐ray structures of 6a and 6b are reported.     

Synthese und Charakterisierung der Siloxialane [H2AlOSiMe3]n und [HAl(OtBu)(OSiMe3)]2 sowie Redoxreaktionen von [H2AlOSiMe3]n und [H2AlOtBu]2 mit einem Zinn(II)‐amid

Synthesis and Characterisation of the Siloxialanes [H₂AlOSiMe₃]_n and [HAl(O^tBu)(OSiMe₃)]₂ as well as the Use of [H₂AlOSiMe₃]_n and [H₂AlO^tBu]₂ as Reducing Agents for a Tin(II) Amide Following the synthesis of [H₂AlO^tBu]₂ ( 1 ) and [HAl(O^tBu)₂]₂ ( 2 ) the siloxialane [H₂AlOSiMe₃]_n ( 3 ) was synthesized and has been subject to single crystal X‐ray analysis for the first time. The molecule 3 is tetrameric (n = 4) in solution and polymeric (n = ∞) in the solid state. 3 is also obtained together with the siloxide [Al(OSiMe₃)₃]₂ ( 5 ) by the reaction of the aluminiumhydride with the double molar amount of trimethylsilanol. The expected monohydride [HAl(OSiMe₃)₂]₂ ( 4 ) was not formed. The heteroleptic monohydride [HAl(O^tBu)(OSiMe₃)]₂ ( 6 ) was synthesized by the reaction of 3 with an equimolar amount of tert‐butanol and was also generated by the addition of trimethylsilanol to an equimolar amount of the alkoxialane [H₂AlO^tBu]₂ ( 1 ). Compound 6 was characterized by single crystal X‐ray diffraction analysis. Additionally we investigated the reducing force of the dihydrides 1 and 3 towards the cyclic diazastannylene Me₂Si(N^tBu)₂Sn ( 7 ). In the course of this reaction Sn^II in 7 was reduced to elementary tin whereas the hydrides were oxidized to hydrogene. Tin is obtained in its β‐form as found by powder‐X‐ray diffraction. The shapes of the metal precipitates (porous, sponge‐like pieces or nanoscaled powders) depend on the conditions of reactions. Besides the elements the spirocyclic aminoalkoxialane [Me₂Si(N^tBu)₂AlO^tBu]₂ ( 8 ) or aminosiloxialane [Me₂Si(N^tBu)₂AlOSiMe₃]₂ ( 9 ) are formed. Structural details of the molecules 8 and 9 can be derived from single crystal X‐ray analyses.     

Einkristalle von La[AsO4] im Monazit‐ und Sm[AsO4] im Xenotim‐Typ

Single Crystals of La[AsO₄] with Monazite‐ and Sm[AsO₄] with Xenotime‐Type Structure Brick‐shaped, transparent single crystals of colourless monazite‐type La[AsO₄] (monoclinic, P2₁/n, a = 676.15(4), b = 721.03(4), c = 700.56(4) pm, β =104.507(4)°, Z = 4) and pale yellow xenotime‐type Sm[AsO₄] (tetragonal, I4₁/amd, a = 718.57(4), c = 639.06(4) pm, Z = 4) emerge as by‐products from alkali and rare‐earth metal chloride fluxes whenever the synthesis of lanthanide(III) oxoarsenate(III) derivatives from admixtures of the corresponding sesquioxides in sealed, evacuated silica ampoules is accompanied by air intrusion and subsequent oxidation. Nine oxygen atoms from seven discrete [AsO₄]^3? tetrahedra recruit the rather irregular coordination sphere of La³⁺ (d(La³⁺?O^2?) = 248 – 266 pm plus 291 pm) and even a tenth ligand could be considered at a distance of 332 pm. The trigonal dodecahedral figure of coordination consisting of eight oxygen atoms at distances of 236 and 248 pm (4× each) about Sm³⁺ is provided by only six isolated tetrahedral [AsO₄]^3? units. Alternating trans‐edge condensation of the latter with the [LaO₉₊₁] polyhedra of monazite‐type La[AsO₄] and the [SmO₈] polyhedra of xenotime‐type Sm[AsO₄] constitutes the main structural chain features along [100] or [001], respectively. The bond distances and angles of the complex [AsO₄]^3? anions range within common intervals (d(As⁵⁺?O^2?) = 167 – 169 pm, ?(O–As–O) = 100 – 116°) for both lanthanide(III) oxoarsenates(V) presented here.     

Spektroskopisches und thermisches Verhalten von K4H2[S2I2O14]

The infrared andRaman spectra of the tittle compound have been recorded and an assignment for the internal vibrations of the H₂S₂I₂O ₁₄ ^4– polyanion is proposed. The thermal behaviour was investigated using TG-, DTA-, IR- and X-ray methods; it is shown that the polyanion breaks down after the release of one mole of H₂O, generating a mixture of -K₂SO₄ and I₂O₅.

     

Darstellung und Kristallstruktur von TICu[CuO2]

Investigations on Electronically Conducting Oxide Systems. XVI. Solid Solutions and Conductivity in the System MgTi₂O₅? Ti₃O₅ Solid solution formation is reported for the system Mg_1–xTi_2–x^IVTi_2x^IIIO₅. With increasing x there is at room temperature a transition from the orthorhombic pseudobrookite structure to the monoclinic low-temperature modification of Ti₃O₅. The X-ray diffraction pattern results are supported by DSC measurements, electrical and magnetic investigations. The tendency of Ti? Ti pair formation in the low-temperature Ti₃O₅ structure is accompanied by a drop of the activation energy for electrical conductivity and a decreasing susceptibility at high Ti^III concentrations.     

Zur Kristallstruktur von KGaO2 und NaGaO2(II) [1]

The Crystal Structure of KGaO₂ and NaGaO₂(II) By annealing intimate mixtures of K₂O, Na₂O and β-Ga₂O₃ (K : Na : Ga = 2.2 : 1.1 : 1) we obtained single crystals of K₂Na₄[(GaO₃)₂] and KGaO₂ (Ag-cylinder; 600°C, 26 d). Structure refinement for KGaO₂ (four-circle diffractometer data, Mo-Kα , 1 390 or 1 390 I_o(hkl); R = 5.55%, R_w = 3.05%) confirms the space group Pbca; a = 552.1 pm, b = 1 107.5 pm, c = 1 580.7 pm, Z = 16. According to K[GaO_4/2] we have a stuffed cristobalite-related structure. Single crystals of NaGaO₂(II) were grown by annealing intimate mixtures of Na₂O₂ and GaAs (Na₂O₂ : GaAs 4.1 : 1) in Ag-cylinders that were not completely closed (570°C, 6 weeks). Structure refinement for NaGaO₂(II) (four-circle diffractometer data, Mo-Kα , 588 of 616 I_o(hkl); R = 4.54%, R_w = 4.06%) confirms the spacegroup Pna2₁; a = 549.8(1) pm, b = 720.6(1) pm, c = 529.8(1) pm, Z = 4. In NaGaO₂(II) we have a wurtzite-related structure.