Estimation of average heat capacities of condensed phase transformation products in the Y−Ba−Cu−O system

A method of calculation of average heat capacities of phase transformation products of complex oxides is suggested. The method takes into account the physical state of products and the increase in the heat capacities of products due to the change of entropy at a phase transformation. Average heat capacities of products formed in a congruous melting of compounds (YCuO₂ and Y₄Ba₃O₉), in an incongruous melting of compounds (Y₂Cu₂O₅, BaCuO₂, BaCu₂O₂, Y₂BaCuO₅, YBa₂Cu₃O₇, YBa₂Cu₃O₆) and in a decomposition in a crystalline state of compounds (Y₂BaO₄, Y₂Ba₂O₅, Y₂Ba₄O₇, Ba₂CuO₃, Ba₃Cu₅O₈, YBa₂Cu_3.5O_7.5, YBa₂Cu₄O₈, YBa₂Cu₅O₉) was estimated by using three methods.     

Surface crystallization and phase transitions of the adsorbed film of F(CF<Subscript>2</Subscript>)<Subscript>12</Subscript>(CH<Subscript>2</Subscript>)<Subscript>16</Subscript>H at the surface of liquid tetradecane

The interaction between a long chain alkane, tetradecane (abbreviated H₁₄), molecule and a semi-fluorinated alkane, 1-perfluorododecyl-hexadecane F(CF₂)₁₂(CH₂)₁₆H (abbreviated F₁₂H₁₆), molecule at the air/ H₁₄ solution interface was studied by measuring the surface tension of the H₁₄ solutions of F₁₂H₁₆ as a function of temperature and bulk concentration under atmospheric pressure. Pure liquid H₁₄ freezes without forming a condensed film at its surface. Nevertheless, a very small amount of F₁₂H₁₆ initiates the surface freezing of H₁₄. In contrast to the F₁₂H₁₆-hexadecane (abbreviated H₁₆) system, the condensed monolayer of H₁₄ has a finite solubility of F₁₂H₁₆ in the F₁₂H₁₆-H₁₄ system. By further increasing the bulk concentration of F₁₂H_16, the F₁₂ chains of the F₁₂H₁₆ molecules form the other closely packed condensed state. Hence, as in the case of the H₁₆ system, the H₁₄ system also exhibits a surface hetero-azeotrope behavior in the lower temperature region. Below the surface hetero-azeotropic point, the condensed H₁₄ monolayer containing a small amount of F₁₂H₁₆ is completely replaced by the condensed monolayer of F₁₂H₁₆. At 2 °C, for example, a surface of H₁₄ solution of F₁₂H₁₆ covered with a gaseous film of F₁₂H₁₆ is replaced by a condensed H₁₄ monolayer containing an almost gaseous state of F₁₂H₁₆, and is then completely replaced by the condensed monolayer of F₁₂H₁₆ with increasing bulk concentration. Above the temperature of the triple point for the F₁₂H₁₆ monolayer, the F₁₂H₁₆-H₁₄ system exhibits a gaseous, expanded, and condensed state.     

Strukturdynamische organometall-komplexe: III. Synthese,struktur und bindungsverhältnisse der komplexe (η5-C5H5)Pd(η1-C5H5)PR3

The complexes (η₅-C₅H₅)Pd(η¹-C₅H₅)PR₃ which are prepared from [Cl(PR₃)-Pd]₂(μ-OCOCH₃)₂ and TlC₅H₅ are fluxional in solution. According to the ¹H and ¹³C NMR spectra at various temperatures, two dynamic processes occur. The process with the higher activation energy is a π/σ (η⁵/η¹) exchange of the two different cyclopentadienyl ligands, whereas the second one with the lower activation energy presumably is a metallotropic rearrangement (1,2-shift). The coalescence temperature for the η⁵/η¹ exchange depends on the size of the phosphine. The X-ray structural analysis of (C₅H₅)₂PdPPrⁱ₃ proves that it exists as a “frozen” η⁵ + η¹ structure in the crystal with the palladium approximately in a square-planar coordination. The η⁵-bonded cyclopentadienyl ring shows some unusual bonding patterns which are obviously electronic in nature. EHT-MO calculations for (η⁵-C₅H₅)PdCH₃(PH₃) indicate that in this model system alternating CC distances in the ring and a stronger bond of the metal to one of the five carbon atoms of the C₅H₅ ligand are to be expected. The calculations suggest that in similar complexes possessing a six-electron donor ligand like C₅H₅^? and a metal fragment which is isolobal to PdCH₃(PH₃)⁺, analogous distortions should be observed. Some reactions of the compounds (η⁵-C₅H₅)Pd(η¹-C₅H₅)PR₃ are described.     

Synthesis and characterization of Er3SmQ6 (Q=S, Se) and Er1.12Sm0.88Se3

The interlanthanide compounds Er₃SmS₆, Er₃SmSe₆, and Er_1.12Sm_0.88Se₃ have been synthesized from stoichiometric reactions of the elements in a KI salt flux at 1273, 1173, and 1123 K, respectively. Er₃SmS₆ and Er₃SmSe₆, which are isostructural and ordered, crystallize in space group P2₁/m in the ScEr₃S₆ structure type whereas Er_1.12Sm_0.88Se₃, in which the Er and Sm atoms are disordered, crystallizes in space group Pnma in the U₂S₃ structure type. Er₃SmS₆ is a paramagnet with a μ_eff=11.25(1) μ_B/mol. From optical measurements a direct band gap of 2.0 eV for light perpendicular to the (100) crystal face of Er₃SmSe₆ is derived whereas for isostructural Er₃SmS₆ an optical transition at 2.2-2.4 eV and a broad absorption peak at lower energies are observed.     

Synthesis and X-ray crystallographic structures of [HGa(NMe2)2]2 and [PhGa(NHNMe2)2]2, and room-temperature conversions of [HGa(NMe2)2]2 to (HGaNH)n and (HGaNMe)n

The reactivity of bis(dimethylamido) complexes of phenyl- and hydridogallium with ammonia, dimethylamine and 1,1-dimethylhydrazine is described. Synthesis of the starting gallium hydride, [HGa(NMe₂)₂]₂, was achieved in nearly quantitative yield from the reaction of HGaCl₂(quinuclidine) with LiNMe₂. In neat ammonia or methylamine at room temperature both dimethylamido ligands in [HGa(NMe₂)₂]₂ were substituted by a single equivalent of NH₃ or MeNH₂ to produce amorphous (HGaNH)_n or (HGaNMe)_n, respectively. In contrast, the reaction of [PhGa(NMe₂)₂]₂ with neat Me₂NNH₂, at room temperature consumed two equivalents of the substituted hydrazine to form [PhGa(NHNMe₂)₂]₂ in a 73% yield. Single crystal X-ray crystallographic analyses of [HGa(NMe₂)₂]₂ and [PhGa(NHNMe₂)₂]₂ establish that in the solid state both compounds adopt a cyclic Ga-N-Ga-N structure with a crystallographic center of symmetry located at the center of the ring.     

Neutral and ion chemistry in a C2H4-SiH4 discharge

This paper reports on a mass spectrometric study of the neutral and ionic species in a low-pressure rf discharge sustained in a C₂H₄-SiH₄ mixture diluted in helium. It is shown that C₂H₄ is readily decomposed into C₂H ₂ ^* and C₂H₃. The formation of secondary products such as C₄H₂, C₄H₄, and C₄H₆ is observed and confirms the presence of C₂H₂ in the discharge. Methylsilane (CH₃SiH₃) and ethylsilane (C₂H₅SiH₃) are also synthesized in this discharge. It is also observed that the major ions C₂H ₄ ⁺ , C₃H ₅ ⁺ , SiH ₃ ⁺ , Si₂H ₄ ⁺ , SiCH ₃ ⁺ , SiC₂H ₃ ⁺ , and SiC₂H ₇ ⁺ are not representative of the direct ionization of neutral species. Their formation is thus interpreted on the basis of ion-molecule reactions.     

Synthesis and properties of fuel cell anodes based on (La0.5 + x Sr0.5 − x )1 − y Mn0.5Ti0.5O3 − δ (x = 0–0.25, y = 0–0.03)

Results are presented of studying electrochemical properties of perovskite-like solid solutions (La_{0.5 + x} Sr_{0.5 ? x} )_{1 ? y} Mn_0.5Ti_0.5O_{3 ? δ} (x = 0–0.25, y = 0–0.03) synthesized using the citrate technique and studied as oxide anodic materials for solid oxide fuel cells (SOFC). X-ray diffraction (XRD) analysis is used to establish that the materials are stable in a wide range of oxygen chemical potential, stable in the presence of 5 ppm H₂S in the range of intermediate temperatures, and also chemically compatible with the solid electrolyte of La_0.8Sr_0.2Ga_0.8Mg_0.15Co_0.05O_{3 ? δ} (LSGMC). It is shown that transition to a reducing atmosphere results in a decrease in electron conductivity that produced a significant effect on the electrochemical activity of porous electrodes. Model cells of planar SOFC on a supporting solid-electrolyte membrane (LSGMC) with anodes based on (La_0.6Sr_0.4)_0.97Mn_0.5Ti_0.5O_{3 ? δ} and (La_0.75Sr_0.25)_0.97Mn_0.5Ti_0.5O_{3 ? δ} and a cathode of Sm_0.5Sr_0.5CoO_{3 ? δ} are manufactured and tested using the voltammetry technique.     

Core Modulation of 70‐Nuclei Core‐Shell Silver Nanoclusters

The reaction of {(HNEt₃)₂[Ag₁₀(tBuC₆H₄S)₁₂]}_n, Ag₂O, Na₂MoO₄, and m‐methoxybenzoic acid (Hmbc) in CH₃OH/CH₂Cl₂ led to yellow crystals of [Ag₄S₄ (MoO₄)₅@Ag₆₆] (SD/Ag70b; SD=SunDi) only, while in the presence of DMF, additional dark‐red crystals of [Ag₁₀@ (MoO₄)₇@Ag₆₀] (SD/Ag70a) were obtained. SD/Ag70b consists of five MoO₄^2? ions wrapped by a shell of 66 Ag atoms, while SD/Ag70a contains a rare Ag₁₀ kernel consisting of five tetrahedra sharing faces and edges, surrounded by seven MoO₄^2? ions enclosed in a shell of 60 Ag atoms. The formation of the Ag₁₀ kernel originates from a reduction reaction during the self‐assembly process that involves DMF. This work provides the structural information of a unique Ag₁₀ kernel (five fused Ag₄ tetrahedra) and paves an avenue to trap elusive silver species with hierarchical multi‐shell silver nanocluster assemblies with the help of anion templates.     

Dithiolylium‐Chlorooxomolybdate(V): Synthese und Kristallstruktur von (C3Cl3S2)[MoOCl4] und (C3Cl3S2)[Mo2O2Cl7]

Dithiolylium Chlorooxomolybdates(V): Synthesis and Crystal Structure of (C₃Cl₃S₂)[MoOCl₄] and (C₃Cl₃S₂)[Mo₂O₂Cl₇] The reaction of 3, 4, 5‐Trichlor‐1, 2‐dithiolylium chloride with MoOCl₃ in dichlormethane under solvothermal conditions at 65 °C simultaneously yields the green tetrachlorooxomolybdate(V) (C₃Cl₃S₂)[MoOCl₄] and the yellow‐brown heptachlorodioxodimolybdate(V) (C₃Cl₃S₂)[Mo₂O₂Cl₇]. The crystal structures of both compounds contain nearly planar (C₃Cl₃S₂)⁺ ions with a S—S bond length of 203 pm. The discrete [MoOCl₄]^— ion in the structure of (C₃Cl₃S₂)[MoOCl₄] has the shape of a square pyramid with the oxygen atom at the apex. The molybdenum atom is displaced by 58 pm from the basal plane towards the oxygen atom. The [Mo₂O₂Cl₇]^— ion in the structure of (C₃Cl₃S₂)[Mo₂O₂Cl₇] has the form of a face‐sharing double octahedron. It is formally composed of a [MoOCl₄]^— ion and a MoOCl₃ molecule connected by one symmetrical and two unsymmetrical chloro bridges. The molybdenum atoms placed in the centers of such connected octahedra are 357 pm apart, indicating no Mo—Mo bond.     

Hammett Correlation in the Accelerated Formation of 2,3-Diphenylquinoxalines in Nebulizer Microdroplets

The accelerated formation of 2,3-diphenylquinoxalines in microdroplets generated in a nebulizer has been investigated by competition experiments in which equimolar quantities of 1,2-phenylenediamine, C₆H₄(NH₂)₂, and a 4-substituted homologue, XC₆H₃(NH₂)₂ [X = F, Cl, Br, CH₃, CH₃O, CO₂CH₃, CF₃, CN or NO₂], or a 4,5-disubstituted homologue, X₂C₆H₂(NH₂)₂ [X = F, Cl, Br, or CH₃], compete to condense with benzil, (C₆H₅CO)₂. Electron-donating substituents (X = CH₃ and CH₃O) accelerate the reaction; in contrast, electron-attracting substituents (X = F, Cl, Br and particularly CO₂CH₃, CN, CF₃ and NO₂) retard it. A structure–reactivity relationship in the form of a Hammett correlation has been found by analyzing the ratio of 2,3-diphenylquinoxaline and the corresponding substituted-2,3-diphenylquinoxaline, giving a ρ value of −0.96, thus confirming that the electron density in the aromatic ring of the phenylenediamine component is reduced in the rate-limiting step in this accelerated condensation. This correlation shows that the phenylenediamine acts as a nucleophile in the reaction.     

Synthesis and crystal structures of coordination polymers,networks and complexes of an adamantane shaped phosphorus–nitrogen cage ligand and cuprous chloride

Reactions of cuprous chloride with the phosphorus–nitrogen cage ligand 2,4,6,8,9,10-hexamethyl-2,4,6,8,9,10-hexaaza-1,3,5,7-tetraphosphaadamantane, P₄(NCH₃)₆, in acetonitrile form distinct solids depending on the ligand-to-metal ratio. Three structurally characterized compounds include: a solvated 3-D network of formula [P₄(NCH₃)₆]₂(CuCl)₃(CH₃CN)₂; a “ladder-type” polymer {[μ₂-P₄(NCH₃)₆]₂(CuCl)₂}_∞; and a monomeric complex [P₄(NCH₃)₆]₂CuCl. Thermal decomposition of the solvated network results in formation of two more materials [P₄(NCH₃)₆]₂(CuCl)₃, and [P₄(NCH₃)₆](CuCl)₂ that are not isolated from solution reactions. The variety of products isolated based solely on ligand-to-metal ratio suggest that this system participates in solution equilibria common to many phosphorus(III) ligands and multiple solubility equilibria.     

Fluordiazadiphosphetidine, 5. Mitt.

Reaction of (CH₃NPF₃)₂ with equimolar amounts of N-methylhexamethyldisilazane yields a reaction product, which can be separated in a polymer and a crystalline fraction. High-vacuum sublimation of the crystalline part yields the already known compound (CH₃N)₄P₃F₇, the new spiro-isomer F₃P(CH₃N)₂PF(CH₃N)₂PF₃ and the spiro-compound F₃P(CH₃N)₂PF(CH₃N)₂PF(CH₃N)₂PF₃, an isomer of the known compound (CH₃N)₆P₄F₈.     

Studies of the reactions of platinum halo complexes with tin(II) halides

The reaction of a dichloromethane solution of a mixture of cis,trans-[PtCl₂(SMe₂)₂] with a tetrahydrofuran solution of SnBr₂ resulted in oxidation of platinum(II) with halogen exchange producing cis,trans-[PtBr₄(SMe₂)₂]. Reaction of a mixture of cis,trans-[PtCl₂(SEt₂)₂], potassium tetrachloroplatinate(II) or potassium hexachloroplatinate(IV) with SnBr₂ in hydrochloric acid solution resulted in formation of predominantly anionic five-coordinate trichlorostannyl platinum(II) complexes. Reaction of potassium tetrabromoplatinate(II) with SnCl₂ in hydrobromic acid in the presence of tetraphenylphosphonium bromide affords cis-[PPh₄]₂[PtBr₂(SnBr₃)₂]. The insertion of SnCl₂ into Pt–Cl bond of platinum(II) complexes cis-[PtCl₂(L₂)] {L₂ = (PPh₃)₂; (PMe₃)₂; {P(OMe)₃}₂; dppm (bis(diphenylphosphino)methane); dppa (bis(diphenylphosphino)amine); and dppe (1,2-bis(diphenylphosphino)ethane)} is described.     

Generation of reactive cyclopentadienylcobalt(I) derivatives by reduction of dicyclopentadienyldicobalt tetraiodide

Reduction of [(C₅H₅)CoI₂]₂ by sodium amalgam in toluene in the presence of 1,3-butadiene, 1,3-cyclohexadiene or 1,5-cyclooctadiene affords the corresponding cyclopentadienylcobalt(I) diolefin complexes in high yields. Reduction of [(C₅H₅)CoI₂]₂ in the presence of 2-butyne yields the binuclear metallocyclic compound (C₅H₅)₂Co₂(C₄(CH₃)₄), previously characterized as a structurally fluxional catalyst for alkyne cyclotrimerisation, as the major product; a trinuclear dicarbyne compound, (C₅H₅)₃Co₃(C-CH₃)₂, is obtained as a minor product. With diphenylacetylene, the analogous phenylcarbyne derivative (C₅H₅)₃Co₃(C-C₆H₅)₂, previously obtained from thermal reaction with (C₅H₅)Co(CO)₂, is obtained along with the major product, the tetraphenylcyclobutadiene complex (C₅H₅)Co(C₄(C₆H₅)₄). Pathways and intermediates for these reactions are discussed.     

The Coordination Chemistry of the Ylide Adduct O2CC(PPh3)2; Preparation,Crystal Structures,and Spectroscopic Properties of [Cl3In{O2CC(PPh3)2}], [Cl2Sn{O2CC(PPh3)2}], and [I2In{O2CC(PPh3)2}2]I

The betain like carbodiphosphorane CO₂ adduct O₂CC(PPh₃)₂ ( 1a ) can serve as a ligand versus hard Lewis acids from main group compounds. Thus, reaction of 1a with InCl₃, InI₃ and SnCl₂ in polar solvents leads to the addition compounds [Cl₃In{O₂CC(PPh₃)₂}] ( 2 ), [Cl₂SnO₂CC(PPh₃)₂}] ( 3 ) and the salt like compound [I₂In{O₂CC(PPh₃)₂}₂]I ( 4 ) in good yields. Whereas in the indium compounds 1a acts as a chelating ligand, in the tin compound the molecule coordinates with one oxygen atom only as a monodentate ligand. 4 has a pyramidal structure with a stereochemical active pair of electrons. All compounds could be characterized by X‐ray analyses and the usual spectroscopic methods.     

Synthetic and structural Studies on Organomolybdenum-Bismuth Halide Complexes

The reactions between either BiBr₂Ph and Na/K[Mo(CO)₃(η? C₅H₅)], [BiPh{Mo(CO)₃(η? C₅H₅)}₂] and BiBr₂Ph, or BiBr₃ and BiPh₃ and [Bi{Mo(CO)₃(η? C₅H₅)}₃] afford the complex [BiBrPh{Mo(CO)₃(η? C₅H₅)}] 1 which has been characterised by X-ray crystallography. Complex 1 comprises a bismuth centre bonded to a bromine atom, a phenyl group and a Mo(CO)₃(η? C₅H₅) fragment together with a longer secondary intermolecular interaction between a bromine from an adjacent molecule which results in a one-dimensional polymeric structure. Addition of a source of bromide anion to 1 affords the anionic complex [BiBr₂Ph{Mo(CO)₃(η? C₅H₅)}]^? 3 ^? although prolonged reaction results in the complex [BiBr₂{Mo(CO)₃(η? C₅H₅)}₂]^? 5 ^? which was characterised by X-ray crystallography as its [Ph₄P]⁺ salt. Complex 5 ^? comprises a mononuclear bismuth centre bonded to two bromine atoms and two Mo(CO)₃(η? C₅H₅) fragments in a geometry which lies between equatorially vacant trigonal bipyramidal and tetrahedral. The complex [PPN]₂[Bi₂Cl₆{Mo(CO)₃(η? C₅H₅)}₂] 8 has also been synthesised and characterised by X-ray crystallography. A dimeric dianion is observed which can be viewed as two edge-shared square-based pyramids with chlorine atoms in the basal planes and Mo(CO)₃(η? C₅H₅) fragments in the apical positions on opposite sides of the Bi₂Cl₆ plane.     

Cluster self-organization of Na-TR-Ge-O-H (TR = La-Lu, Y, and Sc) germanate systems: Suprapolyhedral precursor clusters and self-assembly of Na2Pr6Ge8O26, Na4Sc2Ge4O13, and Na5ScGe4O12 crystal structures

In an M-T-O model system (M is a polyvalent metal; T = Ge or Si), we consider initial stages of formation of cyclic MT clusters and the mechanism of their modification by T tetrahedra. The polyhedron ratio T/M in clusters increases progressively during modeling from one in M₂T₂ to two (M₂T₂ + 2T = M₂T₄), three (M₂T₂ + 2T₂ = M₂T₆), and four (M₂T₂ + 2T + 2T₂ = M₂T₈). These types of clusters were used to find precursor clusters for T-condensed structures of Na₂Pr₆Ge₈O₂₆, Na₄Sc₂Ge₄O₁₃, and Na₅ScGe₄O₁₂. The TOPOS program package was used to carry out the complete 3D reconstruction of the self-assembly of Na,TR germanates: precursor cluster → primary chain → microlayer → microframework (supraprecursor) → ... framework. In all structures, as previously in six orthotetrahedral Na,TR germanate structures, the basic invariant type of four-polyhedral cyclic precursor cluster M₂T₂ was identified; this cluster is built of TR polyhedra, with CN = 6 or 7, linked via orthotetrahedra. The features of the generation of a Ge radical were considered in the form of a Ge₂O₇ chain and a Ge₄O₁₂ ring in various layers of the Na₂Pr₆Ge₈O₂₆ composite structure, a Ge₄O₁₃ chain in Na₄Sc₂Ge₄O₁₃, and a Ge₁₂O₃₆ ring in the Na₅ScGe₄O₁₂ superionic conductor. Original Russian Text ? G.D. Ilyushin, L.N. Dem’yanets, 2009, published in Zhurnal Neorganicheskoi Khimii, 2009, Vol. 54, No. 3, pp. 484–496.     

Orienting Effect of the Cage Addends: The Case of Nucleophilic Cyclopropanation of C2‐C70(CF3)8

C₂‐C₇₀(CF₃)₈ was found to be a very promising substrate in the Bingel and the Bingel–Hirsch reactions combining perfect regioselectivity with much higher reactivity compared to its analogs. The reactions with diethyl malonate yield a single isomer of the monoadduct C₇₀(CF₃)₈[C(CO₂Et)₂] and a single C₂‐symmetrical bisadduct C₇₀(CF₃)₈[C(CO₂Et)₂]₂. The Bingel–Hirsch variation is particularly interesting in that it additionally affords, in a similar regioselective manner, the unexpected alkylated derivatives C₇₀(CF₃)₈[CH(CO₂Et)₂]H and C₇₀(CF₃)₈[C(CO₂Et)₂][CH(CO₂Et)₂]H. The novel compounds have been isolated and structurally characterized by means of ¹H and ¹⁹F NMR spectroscopy as well as single‐crystal X‐ray diffraction. The mechanistic and regiochemical aspects of the reaction are explained with the aid of DFT calculations.     

Über die Reaktion von 2,2-Dimethylpropylidinphosphan mit Molybdänpentachlorid; die Kristallstruktur von [Mo2Cl6(α,α′-Dipyridyl)3]

Reaction of 2,2-Dimethylpropylidynephosphine with Molybdenum Pentachloride; Crystal Structure of [Mo₂Cl₆(α,α′-dipyridyl)₃] 2,2-Dimethylpropylidynephosphine and molybdenum pentachloride dissolved in POCl₃ react with oxydation of the phosphorus and reduction of the molybdenum atom to give the alkyne complex [Mo₂Cl₄(μ-Cl)₂(μ-H₉C₄? C?C? C₄H₉)(OPCl₃)₂]. Addition of α,α′-dipyridyl or of methyltriphenylphosphonium chloride in dichloromethane results in a displacement of the ligands POCl₃ and H₉C₄? C?C? C₄H₉ from this complex and in the formation of [Mo₂Cl₆(dipy)₃] or [(H₅C₆? )₃P? CH₃]₃[Mo₂Cl₉]. Besides the latter compound small amounts of [(H₅C₆? )₃P? CH₃]₂[MoCl₆] can be isolated from the reaction mixture. [Mo₂Cl₆(dipy)₃] which has already been prepared by other methods crystallizes in the monoclinic space group P2₁/c with {a = 1612; b = 148; c = 1296 pm; γ 109.3°; Z = 4} at 20°C. As shown by a crystal structure determination the complex is built up from [MoCl₂(dipy)₂]⁺ cations and [MoCl₄(dipy)]^? anions. The molybdenum atoms are both octahedrally surrounded. With average values of 238 and 243 pm the Mo? Cl bond distances in the cation, where a cis-arrangement of the chlorine atoms is observed, and in the anion differ significantly from each other. [Mo₂Cl₆(dipy)₃] which has already been prepared by other methods crystallizes in the monoclinic space group P2₁/c with {a = 1612; b = 148; c = 1296 pm; γ = 109.3°; Z = 4} at 20°C. As shown by a crystal structure determination the complex is built up from [MoCl₂(dipy)₂]⁺ cations and [MoCl₄(dipy)]^? anions. The molybdenum atoms are both octahedrally surrounded. With average values of 238 and 243 pm the Mo? Cl bond distances in the cation, where a cis-arrangement of the chlorine atoms is observed, and in the anion differ significantly from each other.     

Superacids Based on Pentafluoroorthotellurate Derivatives of Aluminum

The new Lewis acid Al(OTeF₅)₃ and its acetonitrile adduct CH₃CN→Al(OTeF₅)₃ were obtained by a simple one-step synthesis in batches of up to 15 g. Al(OTeF₅)₃ and the adduct were characterized by vibrational spectroscopy (IR, Raman) and quantum-chemical calculations. Furthermore, five different salts of the new weakly coordinating anion [Al(OTeF₅)₄]⁻ were prepared in a two-step procedure. [Ph₄P][Al(OTeF₅)₄], Cs[Al(OTeF₅)₄], [Ph₃C][Al(OTeF₅)₄], as well as the protonated benzene derivatives [C₉H₁₃][Al(OTeF₅)₄] and [C₆H₇][Al(OTeF₅)₄] were characterized by low-temperature single-crystal X-ray diffraction and NMR spectroscopy. Arenium salts have rarely been characterized in the solid state and were synthesized in this work in a simplified fashion.