Über die Synthese und spektroskopische Charakterisierung von Strontium‐ und Bariumtetrabromoferrat(III) und die Kristallstruktur von Ba(FeBr4)2

Preparation and Spectroscopic Characterization of Strontium and Barium Tetrabromoferrate(III) and the Crystal Structure of Ba(FeBr₄)₂ The synthesis of the hitherto unknown bromoferrates(III) of alkaline‐earth metals was carried out by heating mixtures of the metals or the binary bromides together with bromine at temperatures of 450 °C and pressures of up to 1500 bar in closed quartz ampoules. The attempts have been successful only with the larger cations of Sr and Ba. In the case of Be, Mg, and Ca only mixtures of the binary bromides with FeBr₃ could be received. By analysis of the Raman and electronic spectra the dark red compounds of Sr and Ba have been characterized as ternary tetrabromoferrates(III) containing tetrahedral FeBr₄ anions. The composition M(FeBr₄)₂ (M = Sr, Ba) has been determined by potentiometric and titrimetric analysis and thermal degradation by thermogravimetry. A single crystal structure determination of Ba(FeBr₄)₂ confirmed the spectroscopic assignments. The orthorhombic crystal structure (space group Pbca; a = 13.054(3) Å; b = 11.093(2) Å; c = 21.764(4) Å; Z = 8) consists of FeBr₄ and BaBr₉ polyhedra.     

Über die Darstellung und die Eigenschaften von σ-Organylwolframpentachloriden

Tungsten hexachloride reacts with dimethyl zinc or diphenyl zinc forming green methyl or phenyl tungsten pentachloride. However, tungsten hexachloride is reduced to tungsten tetrachloride on addition of zinc dialkyls with longer alkyl groups. Furthermore, alkyl tungsten pentachlorides can be prepared from tungsten hexachloride and tin tetraalkyls or boron trialkyls.     

Über die oxidative Fluorierung von (CF3)(R) (R = CF3, Cl) und die Kristallstruktur von (CF3)(Cl)F+ AsF6−

Oxidative Fluorination of (CF₃)(R) (R = CF₃, Cl) and the Crystal Structure of (CF₃)(Cl) F⁺ AsF₆^? Oxidative fluorination of (CF₃)(R) (R = CF₃, Cl) with XeF⁺MF₆^? (M = As, Sb) in anhydrous HF results in formation of monofluorsulfonium hexafluorometalates. The salts are characterized by vibrational, NMR, and mass spectra. (CF₃)(Cl)F⁺ AsF₆^? crystallizes in the monoclinic space group P2₁/c with a = 9.955(10) Å, b = 11.050(5) Å, c = 12.733(15) Å, β = 97.77(5)°, and Z = 4.     

Über die Synthese von Erdalkalimetalldihalogeniden und die Strukturen von Ca3Br2CBN und Sr3Cl2CBN

On the Synthesis of Alkaline-Earth Dihalides and the Structures of Ca₃Br₂CBN and Sr₃Cl₂CBN The reaction of alkaline-earth carbonates with ammonium chloride or bromide yields alkaline-earth dihalides at relatively low temperatures (300°C). Ca₃Br₂CBN and Sr₃Cl₂CBN were synthesized in sealed niobium containers at 950°C from the metal, its dihalide, boron nitride and graphite. The crystal structure of Sr₃Cl₂CBN was refined from single crystal data. Sr₃Cl₂CBN crystallizes isotypic with Ca₃Cl₂CBN in the orthorhombic space group Pnma (No. 62) with a = 1448.4(2) pm b = 405.46(5) pm, c = 1170.0(1) pm. The lattice constants of Ca₃Br₂CBN and Sr₃Cl₂CBN were determined by orthorhombic indexing of the powder patterns (Ca₃Br₂CBN: a = 1444.3(2) pm, b = 390.64(6) pm, c = 1139.2(2) pm; Sr₃Cl₂CBN: a = 1444.0(4) pm, b = 405.27(8) pm, c = 1167.8(2) pm). There was no success in preparing homologues with Barium.     

Über die Kristallstruktur von (C6H5)3SiSH und (C6H5)3SiSBr und die Darstellung des Iodsulfans (C6H5)3SiSI

The Crystal Structure of (C₆H₅)₃SiSH and (C₆H₅)₃SiSBr and the Preparation of the Iodosulfane (C₆H₅)₃SiSI The preparation of the halogenosulfanes Ph₃SiSBr and Ph₃SiSI from Ph₃SiSH and N-halogenosuccinimide is reported. They are characterized by vibrational spectroscopic measurements. Ph₃SiSBr crystallizes in space group P1 with a = 899.3(8) pm, b = 941.3(7) pm, c = 1 051.4(7) pm, α = 109.88(5)°, β = 99.23(6)°, γ = 96.78(6)° and Z = 2. Ph₃SiSH crystallizes in space group P2₁/c with a = 1 879.4(8), b = 966.3(5), c = 1 845.2(9), β = 107.84(4), Z = 8. The halogenosulfanes decompose in polar solvents by formation of sulphur and triphenylsilanhalide.     

Über die Synthese von Tris(trimethylsilyl)silyl-kalium, -rubidium und -caesium und die Molekülstrukturen zweier Toluolsolvate

About the Synthesis of Tris(trimethylsilyl)silyl Potassium, Rubidium and Cesium and the Molecular Structures of two Toluene Solvates . Solventfree tris(trimethylsilyl)silyl potassium ( 1 ), rubidium ( 2 ) and cesium ( 3 ) are obtained by the reaction of the zink group bis[tris(trimethylsilyl)silyl] derivatives with the appropriate alkali metal in n-pentane. Addition of benzene or toluene to the colourless powders yields deeply coloured solutions. From these solutions single crystals of tris(trimethylsilyl)silyl rubidium—toluene (2/1) ( 2 a ) and tris(trimethylsilyl)silyl cesium—toluene (2/3) ( 3 a ) suitable for X-ray structure analysis are iso- lated [ 2a : orthorhombic; P2₁2₁2₁; a = 1 382.1(3); b = 1 491.7(5); c = 2 106.3(6) pm; Z = 4 (dimers); 3a : orthorhombic; P2₁2₁2₁; a = 2 131.0(6); b = 2 833.1(2); c = 925.2(2) pm; Z = 4 (dimers)]. The central structure moieties are folded four-membered Rb₂Si₂ and Cs₂Si₂ rings, respectively. Small Si? Si? Si angles (100 to 104°) on the one hand and extreme highfield ²⁹Si-NMR shifts of the central silicon atoms on the other hand indicate a strong charge transfer from the alkali metal atoms to the tris(trimethylsilyl)silyl fragments, i.e. mainly ionic interactions between alkalimetal and silicon atoms.     

Über die Darstellung von Tricyanmethanidometallbromiden und Organometalltricyanmethaniden durch Reaktionen mit Bromtricyanmethan BrC(CN)3

Different reactions of BrC(CN)₃ with metal bromides (MBr₄; M = Sn, Ti, Zr), metal organyles (SnR₄, MR₂ (R = C₂H₅, C₆H₅; M = Zn, Cd), C₆H₅HgBr) and with phosphorus tribromide are reported. These reactions lead to the formation of new compounds of the types MBr₃NCC(CN)₂, R₃MNCC(CN)₂, RMNCC(CN)₂ and PBr₄NCC(CN)₂, respectively. The structures of the new compounds are discussed, using results of infrared spectroscopic measurements. Mostly the pseudohalide group C(CN)₃ is bonded to the metal via the nitrogen of a cyano group. Unsolubility and IR spectra are characterizing the compounds of the types MBr₃NCC(CN)₂ and RMNCC(CN)₂ as coordination polymers. IIb-metal derivatives form pyridine complexes [RMNCC(CN)₂(C₅H₅N)₂].     

Nachweisreaktionen und die quantitative Bestimmung von Flavonderivaten (FL)

Analytical and Bioanalytical Chemistry -     

Die kationische Polymerisation von Ketenacetalen und die Darstellung und Charakterisierung von Poly(1,3-diketonen)

Ohne Zusammenfassung     

Synthese und Struktur von γ-Halogenpropyl-octa(silasesquioxanen)

Synthesis and Structures of γ-Halopropyl-octa(silasesquioxanes) As a more rapid and versatile synthetic approach, we have studied the FeCl₃-catalyzed hydrolytic polycondensation of suited trichlorosilanes in a biphasic system which yields e.g. the new octa(silasesquioxane) (BrCH₂CH₂CH₂)₈Si₈O₁₂.     

Über die Umsetzung von Mangan(III) mit Acetylchlorid und die Fällung von Chloromanganaten in Essigsäure

In accordance with spectrophotometric measurements, manganese(III) acetate dihydrate reacts with dilute solutions of acetyl chloride in acetic acid through a 1:1 complex to a red-violet 1:4 compound which is unstable due to the oxidation potential of Mn^III ions. The action of potassium acetate on solutions of Mn^III in acetic acid in presence of a large excess of acetyl chloride leads to a dismutation of managanese(III) and initial precipitation of potassium chloromanganate(IV), K₂MnCl₆. During the reaction of potassium acetate with solutions of manganese(II)/acetic acid/acetyl chloride, under particular conditions, first nonsolvated potassium trichloromanganate(II), KMnCl₃, is formed, which transforms during further addition of potassium ions to tetrapotassium hexachloromanganate(II), K₄MnCl₆.     

Über die Diphosphate M4(P2O7)3 mit M = V,Cr und die Elektronenspektren von Vanadium (III)- und Chrom(III)-Phosphaten

On the Diphosphates M₄(P₂O₇)₃ with M = V, Cr and the Electronic Spectra of Vanadium(III) and Chromium(III) Phosphates Single crystals of ochre colored or dark brown V₄(P₂O₇)₃ ( I ) can be obtained by thermal transformation of an amorphous intermediate synthesized from V₂O₅ and aqueous H₃PO₃ and H₃PO₄; brown crystals of Cr₄(P₂O₇)₃ ( II ) are formed during thermal decomposition of Cr(PO₃)₃, C. I and II are isostructural, crystallizing in orthorhombic space group Pbn2₁ or Pbnm with Z = 4 and lattice constants a = 9.601(2), b = 21.425(5), c = 7.470(4) Å and a = 9.38(1), b = 21.00(4), c = 7.26(2) Å, respectively. Probably due to slight substitution of vanadium(V) for phosphorus atoms (P:V^v ～ 40:1) nonstoichiometic phase composition is found for I prepared at T ～ 1400°C. I and II are characterized by IR and electronic spectroscopy; their electronic spectra are discussed in comparison with those of fourteen other V^III and Cr^III phosphates. This includes a discussion of optical properties of CsCrP₂O₇ changing color from brown to green on change from daylight to artificial light. Some conclusions on the structural arrangement of I and II are drawn.     

Über die Synthese von 2-(p-Biphenylyl)-isopropyloxycarbonyl-(Bpoc)-Aminosäuren und den Zerfall von Aralkyl-phenyl-carbonaten

The syntheses of a number of new Bpoc-amino acids and the preparation of some activated esters of Bpoc-amino acids are described. In recent work on the total synthesis of calcitonin hormones the Bpoc residue has been found to be very useful for the selective protection of α-amino groups of complicated intermediate peptide fragments. The reagent preferentially used for the introduction of the Bpoc group into amino acids, [2-(p-biphenylyl)-isopropyl]-phenyl-carbonate (I), is stable at 0°, but undergoes at higher temperatures a decomposition which is a accelerated by phenol. Based on the reaction products formed — [2-(p-biphenylyl)-isopropyl]-phenyl-ether (II), 2-(p-biphenylyl)-propene (III), and phenol — a scheme is proposed for this thermal decomposition, and the possibility of a correlation between the stability of carbonates R₃C—O—CO—OC₆H₅ and the rate of the acidolytic cleavage of urethanes R₃C—O—CO—NHR′ depending on the substituents R is discussed.     

Über die Synthese von Hydrazinium-hexafluorovanadat(III) und Hydrazinium-hexafluorochromat(III)

Ohne Zusammenfassung     

Einfluß der Ringatome auf die Struktur von Triel‐Pentel‐Heterozyklen – Synthese und Molekülstrukturen von [Me2InAs(SiMe3)2]2 und [Me2InSb(SiMe3)2]3

Influence of the Ring Atoms on the Structure of Triel‐Pentel Heterocycles – Synthesis and X‐Ray Crystal Structures of [Me₂InAs(SiMe₃)₂]₂ and [Me₂InSb(SiMe₃)₂]₃ Triel‐pentel heterocycles [Me₂InE(SiMe₃)₂]_x have been prepared by dehalosilylation reactions from Me₂InCl and E(SiMe₃)₃ (E = As, x = 2; E = Sb, x = 3) and characterised by NMR spectroscopy and by X‐ray crystal structure analyses. In addition the X‐ray crystal structures of [Me₂GaAs(SiMe₃)₂]₂ and [Me₂InP(SiMe₃)₂]₂ are reported. The compounds complete a family of 13 identically substituted heterocycles [Me₂ME(SiMe₃)₂]_x (M = Al, Ga, In; E = N, P, As, Sb, Bi; x = 2, 3), whose structures were investigated depending on the ring atoms M and E. The tendencies that have been observed concerning the ring sizes can be explained by the interplay of the atomic radii of the central atoms and the sterical demand of the ligands. After a formal separation of the M–E bonds in σ bonds and dative bonds the characteristic differences and trends in the endocyclic and exocyclic bond angles of both centres M and E can be interpreted on the basis of a simple Lewis acid/base adduct model.     

Über die Verdampfungsthermodynamik und die Bildungsenthalpien von CaSe,SrSe und BaSe

On the Thermodynamics of Vaporization and the Enthalpies of Formation of CaSe, SrSe and BaSe The congruent vaporization of the solid compounds CaSe, SrSe and BaSe of stoichiometric composition was studied over the temperature ranges 1832?2138 K, 1862?2122 K and 1860?2158 K, respectively, by the Knudsen effusion weight-loss method. Using enthalpy and entropy data from the literature for gaseous M, MSe, Se₂ and Se (M = Ca, Sr, Ba) and estimated data for the standard entropies and enthalpy functions of solid MSe, it can be shown that within the given temperature ranges CaSe and SrSe vaporize predominatly to the atomic species, while in case of BaSe the mode of vaporization to the atoms and to the molecular species BaSe are of about equal importance. The Se₂-content of the gas phase is very small in all cases. The following second and third law enthalpies and entropies (indices II and III respectively) were derived for the vaporization to the gaseous elements: see “Inhaltsübersicht”. The following standard enthalpies of formation of MSe(s) were derived from the third law enthalpies (in kJ · mol^?1): CaSe: ?445 ± 44; SrSe: ?451 ± 42; BaSe: ?467 ± 44.     

Die Kristall- und Molekülstrukturen von (Me2SiNCN)4 (1) und Me3SiNCNSiMe3 (2)

Crystal and Molecular Structures of (Me₂SiNCN)₄ (1) and Me₃SiNCNSiMe₃ (2) Synthesis, spectroscopic characterization (NMR, IR, Raman and MS) and crystal structure of the novel compound 1 are described. The molecules form almost planar 16 membered rings with four SiMe₂-groups connected to four NCN groups. The corresponding compound 2 exhibits a phase transition from the HT phase 2a to the LT phase 2b at 131 K. Consecutive X-ray structure determinations of the molecular structures of both modifications were performed on a crystal, grown in situ on the diffractometer at 231 K.     

Kristall- und Molekülstruktur von fac-Trichloro-tris(dimethylsulfoxid)bismut(III) BiCl3(DMSO)3

Crystal and Molecular Structure of fac-Trichloro-tris(dimethyl sulfoxide)bismuth(III) BiCl₃(DMSO)₃ Crystals of the known, although structurally not characterized title compound were fortuitously obtained from a reaction mixture containing (CH₃)₃SiN(SO₂CH₃)₂, BiCl₃, DMSO, CH₂Cl₂ and CH₃NO₂. Crystallographic data (at ?130°C): triclinic, space group P1 1, a = 816.1(5), b = 885.1(6), c = 1 360.6(8) pm, α = 77.58(3), β = 77.39(3), γ = 64.42(3)°, U = 0.8569 nm³, Z = 2. The DMSO ligands are bound through oxygen to the Bi atom. Important bond distances and angles in the resulting fac-octahedral complex are as follows: Bi? Cl 258.9, 261.0, 263.0, Bi? O 242.6, 245.7, 246.1 pm; Cl? Bi? O (trans) 170.3, 170.6, 176.9, Cl? Bi? Cl 94.6, 94.7, 96.0, O? Bi? O 81.7, 85.4, 87.9, Cl? Bi? O (cis) in the range 87.2–92.6, Bi? O? S 123.4, 126.1, 129.6°.