Einige Reaktionen mit [Mo6Cl8]Cl4

Some Reactions with [Mo₆Cl₈]Cl₄ The reaction of [Mo₆Cl₈]Cl₄ with different chemical agents has been investigated: The methoxylation depends on the CH₃O^? concentration in CH₃OH. The reaction with HF leads to a partial fluorinated [Mo₆Cl₈] product. With NH₄F (NH₄)₂[Mo₆Cl₈]F₆ in formed, the hydrolysis of which leads to [Mo₆Cl₈]F₃(OH) · 2.5 H₂O. This compound can be decomposed thermically into [Mo₆Cl₈]O₂. [Mo₆Br₈]F₆^2? on hydrolysis leads to [Mo₆Br₈]F₃(OH) · 5 H₂O. With CsF Cs₂[Mo₆Cl₈]F₆ is formed, which by hydrolysis is transformed into [Mo₆Cl₈]F₃(OH) · 2.5 H₂O and possibly to [Mo₆Cl₈]F₄ · xH₂O(?). In reaction of [Mo₆Cl₈]Cl₄ with H₂SO₄ one gets [Mo₆Cl₈](SO₄)₂. Salts e. g. [(C₆H₅)₄As]₂[Mo₆Cl₈](OC₆F₅)₆ and adducts e. g. [Mo₆Cl₈](OC₆F₅)₄ · 2 HMPA are prepared. The compounds have been characterized by X-ray powder-diagramms and by IR-spectra.     

Constitutional Isomerism of BiW6Cl15: (BiCl)[W6Cl14] and (BiCl2)[W6Cl13]

The compound (BiCl)[W₆Cl₁₄] was previously characterized as a product of the reduction of tungsten hexachloride with elemental bismuth. Another modification of BiW₆Cl₁₅ is now presented as (BiCl₂)[W₆Cl₁₃], based on the results of an X‐ray single crystal structure determination (space group P2₁/c, a = 1354.3(2) pm, b = 1234.4(2) pm, c = 1538.9(2) pm, and β = 118.76(1) °). The structure of (BiCl₂)[W₆Cl₁₃] contains chains of [(W₆Cl₈ⁱ)Cl₄^aCl_2/2^a–a]^– clusters bridged by chlorine atoms. The (BiCl₂)⁺ counterion exhibits two short Bi–Cl distances of 244.1(4) and 245.9(3) pm, respectively.     

Die Massenspektren von Pd6Cl12, Pt6Cl12 und PdnPt6−nCl12

Mass Spectra of Pd₆Cl₁₂, Pt₆Cl₁₂, and Pd_nPt_6?nCl₁₂ Pd₆Cl₁₂, and Pt₆Cl₁₂ and both together are volatilised in a mass spectrometer. 3 Cl and 1 Pd have approximately the same mass, therefore isotopes of Pd and Pt are used (¹⁰⁸Pd, ₁₉₄Pt). With an ionisation energy of 50 eV part of the vapourised molecules is strongly fragmented. With a lower ionisation energy the molecule ions Pd₆Cl₁₂⁺, Pt₆Cl₁₂⁺ and Pd_nPt_6?nCl₁₂⁺ are only observed.     

The DMSO Solvated octahedro-[W6Cl]Cl Cluster Molecule

Octahedro-hexatungsten octadecachloride, W₆Cl₁₈, is soluble in dimethyl sulfoxide (DMSO). Brownish black crystals of W₆Cl₁₈(DMSO)₄ are formed from the brown solution by evaporation of DMSO under dynamic vacuum. The compound crystallizes monoclinically in the space group P2₁/n (no. 14) with a = 10.420 Å, b = 9.271 Å, c = 20.828 Å, β = 91.10° and Z = 2. The crystal structure is formed by isolated cluster molecules [W₆Cl]Cl of the hexameric tungsten trichloride and DMSO molecules. It is the first hierarchical variant of the tetragonal BaAl₄ type of structure where all atoms of the intermetallic phase are substituted by neutral molecules. The mean bond lengths are d(W–W) = 2.878 Å, d(W–Clⁱ) = 2.391 Å and d(W–Cl^a) = 2.447 Å. They will be discussed in relation to analogous clusters. The two crystallographically independent DMSO molecules (d(S–O) = 1.53–1.55 Å, d(S–C) = 1.65–1.78 Å) form a 3 D net of condensed < 4⁸6⁴ > dodecahedra which envelopes the clusters.     

Pt6Cl12·(1,2,4‐C6H3Cl3), a Structurally Characterized Cocrystallization Product of Pt6Cl12

The reaction of platinum(II) chloride with 1,2,4‐trichlorobenzene gives the novel platinum complex Pt₆Cl₁₂·(1,2,4‐C₆H₃Cl₃). It is the first example of an cocrystallization product of platinum(II) chloride and organic molecules whose crystal structure has been established.     

NaEu2Cl6 und Na0,75Eu2Cl6: Gemischtvalente Chloride des Europiums mit Natrium

NaEu₂Cl₆ and Na_0.75Eu₂Cl₆: Mixed Valent Chlorides of Europium with Sodium The reaction of Na₂EuCl₅ with Eu metal in sealed gold tubes yields blue single crystals of NaEu₂Cl₆. It crystallizes with the hexagonal crystal system (space group P6₃/m) with a = 755.74(8) pm, c = 429.81(5) pm, Z = 1; the structure is closely related to the UCl₃-type. Green single crystals of Na_0.75Eu₂Cl₆ were first obtained as a by-product in the synthesis of Na₂EuCl₅ in evacuated silica tubes and may be prepared by reduction of EuCl₃ with sodium. Na_0.75Eu₂Cl₆ crystallizes isotypic to NaEu₂Cl₆ with a = 753.69(11) pm and c = 416.3(2) pm.     

Synthesis and structures of Sc7Cl12 and Zr6Cl15

The indicated nine-electron clusters of scandium and zirconium are formed in transport reactions at 880/900°C and 750/600°C, respectively. Sc₇Cl₁₂ (R¯3, a – 12.959(2), c – 8.825(2), Z – 3) can be described as c.c.p. Sc₆Cl₁₂ clusters with isolated metal atoms in all octahedral interstices or as Sc³⁺(Sc₆Cl₆ⁱCl₆^i?a) ^3? with Sc³⁺ in Clⁱ octahedra between Sc₆Cl sheets. Metal-metal distances within the cluster are 3.201?3.230(2) Å. Zr₆Cl₁₂ⁱCl crystallizes in the Ta₆Cl₁₅ structure (Ia3d, a – 21.141(3) Å, Z – 16) with d(Zr? Zr) = 3,199–3.214(4) Å. Apparent residual electron density is found in the center of both clusters, amounting to Z～7.6 (Sc) and ～6 (Zr) based of refinement of oxygen in these positions. The effect is thought to probably arise from errors in the diffraction data rather than partial incorporation of light nonmetal atoms such as oxygen or fluorine. Observed metal-metal distances are compared with those in other clusters.     

Die Leiterstruktur von LiNb6Cl19

The Ladder Structure of LiNb₆Cl₁₉ LiNb₆Cl₁₉ was obtained from a solid state reaction of Nb powder, NbCl₅, and Li₂C₂ at 530 °C. The structure was refined by single‐crystal X‐ray diffraction (space group Pmma (No. 51), Z = 2, a = 2814.6(1) pm, b = 687.35(5) pm, c = 641.39(3) pm). It contains edge and face bridging [NbCl₆] octahedra forming the motif of a ladder. The parallel alignment of ladders yields a one‐dimensional structure, with lithium ions occupying voids. Each ladder combines characteristic fragments from the niobium chloride structures NbCl₄, A₃Nb₂Cl₉ (A = Rb, Cs), and Nb₃Cl₈. The arrangement of niobium atoms in LiNb₆Cl₁₉ appears to be similar with trigonal niobium clusters obtained in the structure of Nb₃Cl₈. The electronic structures of niobium clusters in Nb₃Cl₈ and LiNb₆Cl₁₉ are compared with each other.     

Die thermodynamische Stabilität der Molekeln Pd6Cl12, Pd6Br12 und Pt6Cl12

Thermodynamic Stability of Pd₆Cl₁₂, Pd₆Br₁₂, and Pt₆Cl₁₂ Molecules Vapour pressure data of PdCl₂ and PdBr₂ taken from the literature have been used to get new informations regarding the vapourization of Pd₆Cl₁₂ molecules. Using mixtures of PdCl₂ and AgBr as source materials, besides Pd₆Cl₁₂ molecules the vapourization of Pd₆Cl_12-nBr_n with n = 1 – 8 has been observed in a mass spectrometer. Semi quantitative observations concerning the vapourization of Pt₆Cl₁₂ molecules from a PtCl₂ solid are reported. Heats of formation and standard entropy data for the molecules Pd₆Cl₁₂, Pd₆Br₁₂ and Pt₆Cl₁₂ are given.     

Cl i /Br-Substitution in der Wolframchlorosäure (H3O)2[W6Cl 8 i ]Cl 6 a ·6H2O

A method for preparing chlorotungstic acid $$(H_3 O)_2 [W_6 Cl_8 i]Cl_6 a \cdot 6H_2 O$$ in good yield is given. On thermal degradation of the acid, the stages $$(H_2 O)_2 [W_6 Cl_8 ]Cl_6 ,[W_6 Cl_8 ]Cl_4 \cdot 2H_2 O and [W_6 Cl_8 ]Cl_4 $$ are isolable. Chlorotungstic acid and its partial Br ⁱ -substitution products can be precipitated almost quantitatively as $$(Oxin \cdot H)_2 [W_6 X_8 ]X_6 $$ When boiled with strong aqueous or aqueous-ethanolic HBr the substitution of Cl ^a and also partial Cl ⁱ /Br substitution occurs. In the same way I ⁱ can be introduced. The inverse reaction (substitution of Br ⁱ by Cl) is not possible. In ethanolic HB in the case of Cl ⁱ /Br substitution an induction period is observed.     

Zur Bildung gasförmiger MCl2-Komplexe. Vergleichende Untersuchung zur Eignung von Al2Cl6, Ga2Cl6, In2Cl6, Fe2Cl6, SiCl4, TiCl4, PCl5, TaCl5 und U2Cl10 als Komplexbildner

Formation of Gaseous MCl₂ Complexes. Comparative Study on the Suitability of Al₂Cl₆, Ga₂Cl₆, In₂Cl₆, Fe₂Cl₆, SiCl₄, TiCl₄, PCl₅, TaCl₅, and U₂Cl₁₀ as Complex Former The thermodynamic data for reactions of the type MCl_2,s + L₂Cl_6,g = ML₂Cl_8,g are – as expected – nearly independent on L(Al, Ga, In, Fe). Transport rates e. g. of CoCl₂ something smaller with L ? Ga may be traced back on uncertainties concerning the Ga₂Cl₆ dissociation, and with L ? Fe they may be traced back on the incorporation of FeCl₂ into MCl_2,s. SiCl₄ and TiCl₄ cause no noticable transport of CoCl₂ or CuCl₂ in a temperature gradient, which leads to a short bond consideration. PCl₅ and TaCl₅ cause the transport of small amounts of CoCl₂. U₂Cl₁₀/UCl₅ are able to transport a remarkable amount of CaCl₂ and CoCl₂, respectively.     

Darstellung von trans-[Mo6Cl8]Cl4Br22−ausgehend von kristallisierten [Mo6Cl8]Cl4(H2O)2 und die Kristallstruktur von [(C6H5)4As]2[Mo6Cl8]Cl4Br2

Preparation of trans-[Mo₆Cl₈]Cl₄Br₂^2? Starting from Crystalline [Mo₆Cl₈]Cl₄(H₂O)₂ and Crystal Structure of [(C₆H₅)₄As]₂[Mo₆Cl₈]Cl₄Br₂ The synthesis of the title compound is successful if the crystallized [(Mo₆Cl₈)Cl₄(H₂O)₂] containing the H₂O molecules in trans-position reacts with HBr + [(C₆H₅)₄As]Br in ethanol in a heterogeneous reaction. The X-ray structure investigation confirms the existence of discrete trans-Br-substituted cluster anions of composition [(Mo₆Cl₈)Cl₄Br₂]^2? in the crystal. The reaction in homogeneous solutions proceeds to Br-enriched compounds. [(C₆H₅)₄As]₂[(Mo₆Cl₈)Cl₄Br₂] crystallizes in the triclinic space group P¯1 with a = 11.071(2), b = 11.418(2), c = 12.813(2) Å, α = 116.10(2), β = 95.27(2) and γ = 94.41(2)° (?133°C). The crystal structure at ?133°C was determined from single crystal X-ray diffraction data (R₁ = 0.026). The [(Mo₆Cl₈)Cl₄Br₂]^2?-anions are not completely ordered but distributed statistically among the three positions which are possible within the limits of the ordered [Mo₆Cl₈]-cores (ratio 11:5:4). The frameworks of the anions consist of Mo₆ cluster units with (slightly distorted) octahedral arrangement of the metal atoms (d(Mo? Mo): 2.600(1) up to 2.614(1) Å), which are coordinated by the halogeno ligands in a square-pyramidal manner. The details of the structure will be discussed and compared with similar [(Mo₆X₈)Y₄] cluster units (X, Y ? Cl, Br).     

KEu2Cl6 und K1, 6Eu1, 4Cl5: Zwei neue gemischtvalente Europiumchloride

KEu₂Cl₆ and K_1.6Eu_1.4Cl₅: Two New Mixed‐Valent Europium Chlorides The reaction of the binary chlorides EuCl₃, EuCl₂ and KCl yields the mixed‐valent compounds KEu₂Cl₆ and K_1.6Eu_1.4Cl₅. KEu₂Cl₆ (hexagonal, P6₃/m, Z = 1, a = 788.87(13), c = 411.41(6) pm, R₁ = 5.40 %) crystallizes with an addition‐variant of the UCl₃‐type of structure with tricapped trigonal prismatic coordination for the europium cations. The K⁺ ions reside in channels along [001] and exhibit extremely large displacement parameters U₃₃. The crystal structure of K_1.6Eu_1.4Cl₅ (orthorhombic, Pnma, Z = 4, a = 1260.49(12), b = 871.05(9), c = 787.18(10) pm, R₁ = 4.77 %) is closely related to that one of K₂EuCl₅ if the K⁺ and the Eu³⁺ ions are partly substituted for Eu²⁺. Absorption spectra show transitions, which can be assigned to Eu²⁺ and Eu³⁺ ions, and additional transitions due to interaction of both cations occupying common positions.     

Pr6C2‐Doppeltetraeder in Pr6C2Cl10 und Pr6C2Cl5Br5

Pr₆C₂‐Bitetrahedra in Pr₆C₂Cl₁₀ and Pr₆C₂Cl₅Br₅ The compounds Pr₆C₂Cl₁₀ and Pr₆C₂Cl₅Br₅ are prepared by heating stoichiometric mixtures of Pr, PrCl₃, PrBr₃ and C in sealed Ta capsules at 810 ? 820 °C. They form bulky transparent yellow to green and moisture sensitive crystals which have different structures: space groups C2/c, (a = 13.687(3) Å, b = 8.638(2) Å, c = 15.690(3) Å, β = 97.67(3)° for Pr₆C₂Cl₁₀ and a = 13.689(1) Å, b = 10.383(1) Å, c = 14.089(1) Å, β = 106.49(1)° for Pr₆C₂Cl₅Br₅). Both crystal structures contain C‐centered Pr₆C₂ bitetrahedra, linked via halogen atoms above edges and corners in different ways. The site selective occupation of the halogen positions in Pr₆C₂Cl₅Br₅ is refined in a split model and analysed with the bond length‐bond strength formalism. The compound is further characterized via TEM investigations and magnetic measurements (μ_eff = 3.66 μ_B).     

Mechanism of pyrolysis of C2Cl6

Using published data on the kinetics of pyrolysis of C₂Cl₆ and estimated rate parameters for all the involved radical reactions, a mechanism is proposed which accounts quantitatively for all the observations: The steady-state rate law valid for after about 0.1% reaction is and the reaction is verified to proceed through the two parallel stages suggested earlier whose net reaction is A reported induction period obtained from pressure measurements used to follow the rate is shown to be compatible with the endothermicity of reaction A, giving rise to a self-cooling of the gaseous mixture and thus an overall pressure decrease. From the analysis, the bond dissociation energy DH⁰(C₂Cl₅? Cl) is found to be 70.3 ± 1 kcal/mol and ΔH_f300⁰(·C₂Cl₅) = 7.7 ± 1 kcal/mol. The resulting π? bond energy in C₂Cl₄ is 52.5 ± 1 kcal/mol.