Das Gleichgewicht zwischen oktaedrisch und tetraedrisch koordiniertem Kobalt(II) in N,N-Dimethylacetamid

Zusammenfassung In Lösung von [Co(DMA)₆](ClO₄)₂ in wasserfr. N,N-Dimethylacetamid (DMA) wird spektrophotometrisch ein Gleichgewicht zwischen tetraedrisch und oktaedrisch koordiniertem Co²⁺ festgestellt. Die GleichgewichtskonstanteK=[Co _tetr ²⁺ ]/[Co _oct ²⁺ ] wurde bei 25°C zu 0,028 und bei 70°C zu 0,19 bestimmt. Bei –8°C zeigen die Elektronenspektren keinen meßbaren Anteil der tetraedrischen Species. Für den oktaedrischen Komplex ergibt sichD _q =805 cm^–1,B=834 cm^–1.

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The equilibrium between octahedral and tetrahedral coordinated cobalt(II) in N,N-dimethylacetamide

Spectrophotometric results establish an equilibrium between tetrahedral and octahedral coordinated cobalt(II) in anhydrous N,N-dimethylacetamide (DMA). The equilibrium constantK=[Co _tetr ²⁺ ]/[Co _okt ²⁺ ] has been found to be 0,028 at 25°C and 0,19 at 70°C. Electronic spectra indicate no measurable amount of the tetrahedral species at –8°C. For the octahedral complexD _q =805 cm^–1 andB=834 cm^–1.

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Mit 4 Abbildungen     

Synthese,Charakterisierung und EPR-spektroskopische Untersuchung von Heteropolyverbindungen mit tetraedrisch bzw. oktaedrisch koordiniertem Eisen(III)

Synthesis, Characterization, and EPR Studies of Heteropoly Compounds with Iron(III) in Tetrahedral and Octahedral Coordination The heteropoly compounds H₅[FeO₄W₁₂O₃₆] · 6 H₂O (a₀ = 1216 pm), H₃[Fe(OH)₆Mo₆O₁₈] · 4 H₂O, Na₅[FeO₄W₁₂O₃₆] · nH₂O and FeH₂[FeO₄W₁₂O₃₆] · 17 H₂O, for the first time obtained in this work by freeze-drying and characterized by means of chemical analysis, i.r. and u.v. spectroscopy, X-ray powder-photographs, and magnetic measurements, appear as suitable model systems for EPR investigations. They contain, like a number of known Fe^III-heteropoly compounds, Fe^III in FeO₄ or/and FeO₆ units, which are isolated from each other by structural reasons. In the Keggin-compounds M₅[E^IIIO₄W₁₂O₃₆] · nH₂O ( I ) (M = Na, Rb, TMA, TEA; E = Fe, Al, B) Fe^III occupies slightly distorted tetrahedral positions (g′ ≈? 2), which are characterized by zfs-values of ≈? 10 mT and line widthes ΔB of 2.0 ?15 mT. Unlike as for I cations with different physico-chemical characteristics have only little effect on the Fe^III-zfs. This holds for the Anderson-complexes M₃[Fe(OH)₆Mo₆O₁₈]·nH₂O, (M = H, K, NH₄, TMA; g′ ≈? 4.3 ΔB ≈? 67 mT) and for M5[SiO₄W₁₁O₃₅FeO₅(OH₂)]·nH₂O, (M = K, TMA; g′ = 4.3 ΔB = 26.5 mT). The FeO₆ octahedra are more distorted than the FeO₄ tetrahedra in I and therefore less susceptible for structural changes.     

Über den Zusammenhang zwischen Struktur und Stabilität von Hydrazinsulfonamiden

Syntheses of twenty new hydrazinesulfonamides are described, and structure-stability relationships and decomposition-mechanisms of these compounds are discussed.

     

Binukleare Nickel(0)-Alkin-Koordinationsverbindungen – Zusammenhang zwischen Ligandperipherie und supramolekularer Struktur

Binuclear Nickel(0) Alkyne Coordination Compounds – Correlation between Ligand Periphery and Supramolecular Structure Reaction of Ni(cdt: 1,5,9-cyclododecatriene) with functionalized alkynes and subsequent reaction with ethylenediamines gives binuclear compounds of the type (diamine)Ni(μ-alkyne)Ni(alkyne). Compounds with alkyne-diols (N?N)Ni₂(HOR¹R²C? C?C? CR¹R²OH)₂ show supramolecular structures in which two identical intramolecular and one intermolecular hydrogen bonds are realized. 1 and 2 (chelate ligand in each case N,N,N′,N′-tetramethylethylenediamine, TMEDA, in 1 R¹ = R² = Me, in 2 R¹ = R² = Et) polymer-like chains are built up by connecting the binuclear units. Via two intermolecular hydrogen bonds per organometallic unit in 1 and via one intermoleculare hydrogen bond in 2 the chains are connected to give double chains. By substitution of one methyl group of TMEDA by hydrogen ( 3 : R¹ = R² = Me) a polymerlike network is produced by connecting the polymer-like chains. In compound 4 in which one of the methyl groups of TMEDA is substituted by CH₂CH₂NMe₂ the polymer-like chains remain unconnected. In 5 (diamine = TMEDA, alkyne = (CH₃)₃C? C?C? CMe₂OH) one intermolecular hydrogen bond per organometallic unit is observed forming again polymer-like chains that are independent of each other.     

Darstellung und Struktur von Tris[2,4,6-tris(trifluormethyl)thiophenolato]indium(III)-diethyletherat

Preparation and Structure of Tris[2,4,6-tris(trifluormethyl)thiophenolato]indium (III) Etherate Reaction of sodium [2,4,6-tris(trifluoromethyl)thiophenolate and InCl₃ in the molar ratio of 1:3 in diethylether forms tris 2,4,6-tris(trifluoromethyl)thiophenolato]indium(III) etherate 1 in 92% yield. 1 was also obtained by reaction of CpIn (Cp = C₅H₅) and C₆H₂(CF₃)₃SH. The structure of 1 is discussed.     

Darstellung und Struktur von Antimon(III)-tris(thiophosphinaten)

Preparation and Structure of Antimony (III) Tris (thiophosphinates) The title compounds are formed by the reaction of Sb(CH₃COO)₃ with thiophosphinic acids R₂P(?S)OH (R = CH₃ cyclo-C₆H₁₁, C₆H₅). The crystal and molecular structures of Sb((cyclo-C₆H₁₁)₂POS)₃ and Sb((C₆H₅)₂POS)₃ have been determined by single crystal X-ray methods. Sb^III is pyramidally coordinated to the oxygen atoms of the R₂POS ligands through short (primary) bonds with a mean length of 203 pm. The Sb? S distances of the mainly chelating ligands vary between 300 and 320 pm (secondary bonds). The lone electron pair is stereochemically active.     

Beziehungen zwischen Lumineszenzspektrum und Struktur von Seltenerdkomplexen. II. Oktaedrisch koordinierte Hexahalogenokomplexe des Europium(III)

The analysis of the luminescence spectra of the pyridinium hexahalogeno complexes of europium(III) (PyH)₃EuCl₆ and (PyH)₃EuBr₆ is in accordance with the presence of a weakly distorted octahedral symmetry at the rare earth site. The parameters calculated from the splitting of the ⁷F₂-level, \documentclass{article}\pagestyle{empty}\begin{document}$ {\rm B}_{{\rm 40}} {\rm (EuCl}_{\rm 6} {\rm - - -) = 159 \pm 4 und B}_{{\rm 40}} {\rm (EuBr}_{\rm 6} {\rm - - -) = 152 \pm 4 cm}^{- {\rm 1}} {\rm,} $\end{document} are about four to five times larger than the parameters calculated theoretically from the electrostatic point-charge model.     

Darstellung und Reaktivität von Tris(dialkylthiophoshinyl)-phosphanen

On the Solubility of LaCl₃ in Hydrochlorid Acid. Comparative Study of the Saturated Metal Chloride ? HCl? H₂O Systems The results of solubility investigations in the LaCl₃? HCl? H₂O system at 15, 25 and 35°C were presented. On the basis of the experimental data, of references and of a model of the authors conclusions were drawn on the structure of the saturated and almost saturated solutions.     

Die Farbreaktion zwischen 4-Aminophenazon und Phenolen in Gegenwart von Kaliumhexacyanoferrat(III)

Ohne Zusammenfassung     

Beziehungen zwischen Lumineszenzspektrum und Struktur von Seltenerdkomplexen. III. Zur Existenz unterschiedlicher Polyedertypen bei Alkalitetrakis(dibenzoylmethanato)europat(III)-Komplexen

The luminescence spectra of alkali tetrakis(dibenzoylmethido)europate(III) complexes in the crystalline state at 77°K have been measured in the spectral region 510–640 nm. The spectra show the existence of different modifications of these compounds. The spectra of the β-forms are consistent with a site symmetry D₂ at the Eu(III) ion, the spectra of the corresponding α-forms with a site symmetry D₄. A conversion from the β-form into the α-form on heating is observed in some cases. The conversion involves a change from dodecahedral into antiprismatic coordination around the Eu(III) ion.     

Synthese und Struktur von Komplexen mit Nitridobrücken zwischen Rhenium und Zink

Synthesis and Structure of Complexes with Nitrido Bridges between Rhenium and Zinc The reaction of [ReNCl₂(PMePh)₃] with ZnX₂ (X = Cl, Br) in CH₂Cl₂ yields the tetranuclear complexes [(Me₂PhP)₃X₂Re≡N–ZnX₂]₂. In case of the reaction with ZnBr₂ an exchange of the halogen atoms coordinated to the Re atom occurs. [(Me₂PhP)₃Cl₂Re≡N–ZnCl₂]₂ ( 1 ) crystallizes with one centrosymmetric tetranuclear complex in the triclinic unit cell. [(Me₂PhP)₃Br₂Re≡N–ZnBr₂]₂ ( 2 ) forms triclinic crystals with the composition 2 · 2 CH₂Cl₂. The centrosymmetric tetranuclear complexes exhibit analogous structures. Two complexes [ReNX₂(PMe₂Ph)₃] coordinate with the terminal nitrido ligands the Zn atoms of a central unit XZn(μ-X)₂ZnX. The resulting linear nitrido bridges Re≡N–Zn (Re–N–Zn = 178.4° ( 1 ) und 178.0° ( 2 )) are asymmetric with distances Re–N = 170 pm and Zn–N = 199 pm for 1 , and Re–N = 167 pm as well as Zn–N = 201 pm for 2 . The reaction of [ReNCl₂(PMe₂Ph)₃] with ZnI₂ in CH₂Cl₂ presumably first affords [(Me₂PhP)₃ClIRe≡N–ZnI₂]₂, which, however, in the course of crystallization decomposes to yield [(Me₂PhP)₃ClIRe≡N–ZnI₂(OPMe₂Ph)] ( 3 ). Of the two Cl atoms originally coordinated at the Re atom the one in cis position to the nitrido ligand is substituted by iodine. 3 forms monoclinic crystals with the space group P2₁/n. The distances in the linear nitrido bridge (Re–N–Zn = 171.5°) are Re–N = 167.9 pm and Zn–N = 204.9 pm. By the reaction of [ReNCl₂(PMe₂Ph)₃] with ZnX₂ (X = Cl, I) in THF the dinuclear complexes [(Me₂PhP)₃Cl₂Re≡N–ZnCl₂(THF)] ( 4 ) and [(Me₂PhP)₃ClIRe≡N–ZnI₂(THF)] ( 5 ) are obtained. They crystallize isotypically as 4 · THF or 5 · THF in the triclinic space group P1. Their nitrido bridges have the following parameters: Re–N–Zn = 175.2°, Re–N = 167.7 pm, and Zn–N = 202.1 pm for 4 , resp. Re–N–Zn = 174.7°, Re–N = 168.3 pm, and Zn–N = 201.2 pm for 5 .