Synthesis of diamantane via skeletal isomerization of hydrogenated cyclohepta-1,3,5-triene dimers in ionic liquid [Et<Subscript>3</Subscript>NH]<Superscript>+</Superscript> [Al<Subscript>2</Subscript>Cl<Subscript>7</Subscript>]<Superscript>–</Superscript>

Diamantane was synthesized in 91–97% yield by skeletal isomerization of a mixture of hydrogenated cyclohepta-1,3,5-triene dimers, pentacyclo[8.4.0.0^3,7.0^4,14.0^6,11]tetradecane and pentacyclo-[7.5.0.0^2,8.0^5,14.0^7,11]tetradecane, at a ratio of 3: 2 in the presence of ionic liquid [Et₃NH]⁺ [Al₂Cl₇]^–.     

Unusual rearrangement of (cyclopropylmethoxy)benzene and its derivatives in the presence of BF<Subscript>3</Subscript>·Et<Subscript>2</Subscript>O

(Cyclopropylmethoxy)benzene and its ortho- and para-bromo-substituted analogs in the presence of BF₃ · Et₂O undergo rearrangement with formation of (cyclobutyloxy)benzene and 2-ethyl-2,3-dihydro-1-benzofuran.     

Synthesis and crystal structure of [Et<Subscript>4</Subscript>N] [Cr(PzTp)Cl<Subscript>3</Subscript>] [PzTp<Superscript>−</Superscript> = Tetra(pyrazolyl) Borate]

Treatment of CrCl₃(THF)₃ with KPzTp in THF affords of the compound K[Cr(PzTp)Cl₃], and the K⁺ in this complex can be replaced by Et₄N⁺ in CH₂Cl₂. Well-defined green crystals of [Et₄N]r(PzTp)Cl₃] (I) suitable for X-ray diffraction are obtained at −₂0°C. In the anion the metal center shows a distorted octahedral geometry with the tetra(pyrazolyl) borate bonded as three N-donor tripod ligands and three chloride atoms completing the coordination sphere.     

Synthesis and structure of the complex [Mo<Subscript>3</Subscript>(μ<Subscript>3</Subscript>-S)(μ<Subscript>2</Subscript>-S<Subscript>2</Subscript>)<Subscript>3</Subscript>(Et<Subscript>2</Subscript>NCS<Subscript>2</Subscript>)<Subscript>3</Subscript>]I

The structure of tri-μ₂-disulfido-μ₃-thiotris(diethyldithiocarbamato)-S,S′-triangle-trimolybdenum iodide [Mo₃(μ₃-S)(μ₂-S₂)₃(Et₂NCS₂)₃]I was determined. The compound was characterized by differential thermal analysis and IR, Raman, and X-ray electronic spectroscopy.     

Structure of sulfanilamide-containing cobalt(III) dioximates with the [ZrF<Subscript>6</Subscript>]<Superscript>2−</Superscript> and [BF<Subscript>4</Subscript>]<Superscript>−</Superscript> anions

The complexes [Co(DH)₂(Sam)₂]₂[ZrF₆]·5H₂O (I) and [Co(DH)₂(Sam)₂][BF₄]·H₂O (II), where DH^? is the dimethylglyoxime monoanion, and Sam is para-aminobenzenesulfamide (sulfanilamide, white streptocid), were synthesized, and their crystal structures were determined by X-ray diffraction analysis. The coordination polyhedron of the Co³⁺ atom is an N₆ octahedron formed by four nitrogen atoms of the two dimethylglyoxime residues and two nitrogen atoms of the Sam fragments. The latter are realized in virtually parallel orientation relative to the polyhedron of the metal atom and its equatorial plane; the average value of the dihedral angles is 26.8(1)°, and there is π-π interaction between the benzene rings of the Sam fragments and the π delocalized equatorial metallocycle. The deviation of the cobalt atom from the four-angle plane is up to 0.009(1) Å. The (Co-N)_DH? and (Co-N)_Sam distances in the [Co(DH)₂(Sam)₂]⁺ complex cations vary from 1.892(2) Å to 1.907(3) Å and from 2.000(2) Å to 2.012(2) Å, respectively. The [ZrF₆]^2? and [BF₄]^? complex anions play the major role in crystal formation; they produce a substantial effect on the formation of a complex system of hydrogen bonds.     

State of active components on the surface of the PdCl<Subscript>2</Subscript>-CuCl<Subscript>2</Subscript>/γ-Al<Subscript>2</Subscript>O<Subscript>3</Subscript> catalyst for the low-temperature oxidation of carbon monoxide

The state of the active constituents of the freshly prepared PdCl₂-CuCl₂/γ-Al₂O₃ catalyst for the low-temperature oxidation of the carbon monoxide by molecular oxygen was studied by X-ray absorption spectroscopy (XAS), powder X-ray diffraction (XRD), scanning electron microscopy (SEM), and diffuse reflectance IR Fourier transform spectroscopy (DRIFTS). It was shown that copper in the form of a crystalline phase of Cu₂Cl(OH)₃ with the structure of the mineral paratacamite and palladium chloride in an amorphous state occurred on the surface of γ-Al₂O₃. According to XAS data, the local environment of palladium consisted of four chlorine atoms, which formed a flat square with an increased distance between palladium and one of the chlorine atoms. The evolution of the local environments of copper and palladium upon a transition from the initial salts to the impregnating solutions and chlorides on the surface of γ-Al₂O₃ was considered. The role of γ-Al₂O₃ in the formation of the Cu₂Cl(OH)₃ phase was discussed. It was found by the DRIFTS method that linear (2114 cm⁻¹) and bridging (1990 and 1928 cm⁻¹) forms of coordinated carbon monoxide were formed upon the adsorption of CO on the catalyst surface. The formation of CO₂ upon the interaction of coordinated CO with atmospheric oxygen was detected. Active sites including copper and palladium were absent from the surface of the freshly prepared catalyst.     

Thermal and BF<Subscript>3</Subscript>⋅Et<Subscript>2</Subscript>O-catalyzed cleavage of 1-hydrohexafluoroisobutenyloxytrimethylsilane. Perfluoromethacrolein,its isomers,dimers, and homopolymers

During vacuum pyrolysis in a quartz or steel tube, 1-hydrohexafluoroisobutenyloxytrimethylsilane (1) eliminates fluorotrimethylsilane to give perfluoromethacrolein, which was detected by NMR. Similar pyrolysis of silane 1 over KF results in E- and Z--hydrotetrafluoromethacryloyl fluorides. At 20 °C, perfluoromethacrolein undergoes homopolymerisation and/or cyclodimerization to yield 4,4-difluoro-2-pentafluoroisopropenyl-5-trifluoromethyl-4H-1,3-dioxin, which rearranges into E-7,7,7-trifluoro-2,6-bis(trifluoromethyl)-4-oxahepta-2,5-dienoyl fluoride under the action of BF₃Et₂O. The same fluoride is also formed, together with fluorotrimethylsilane, directly from silane 1 under the action of BF₃Et₂O.Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 8, pp. 1629–1635, August, 2004.Deceased     

Trinuclear Metal Clusters with Three Different Metal Atoms from the Insertion of CpCo and Cp*Rh Groups into the S–S Bonds of [CpFeMn(CO)<Subscript>5</Subscript>(μ-S<Subscript>2</Subscript>)]<Subscript>2</Subscript><Superscript>†</Superscript>

Two cobalt containing products CpCoMn₂(CO)₆(μ₃-S)₂, 2 and Cp₂FeCoMn(CO)₃(μ₃-S)₂, 3 were obtained from the reaction of [CpFeMn(CO)₅(μ-S₂)]₂, 1 with CpCo(CO)₂ at room temperature. The two rhodium containing products: Cp*RhMn₂(CO)₆(μ₃-S)₂, 4 (11% yield) and CpFeCp*RhMn(CO)₃(μ₃-S)₂, 5 (9% yield), were obtained from the reaction of 1 with Cp*Rh(CO)₂. Compounds 3 and 5 were characterized structurally by single crystal X-ray diffraction methods. Compounds 3 and 5 both contain triangular clusters of three different types of metal atoms and have triply bridging sulfido ligands on each side of the cluster. A mechanism for their formation from 1 is proposed.^†Dedicated to F. A. Cotton on the occasion of his 75th birthday.     

Study of Acidic (Tetracaprolactam) Dodecamolybdosilicate of the Composition (C<Subscript>6</Subscript>H<Subscript>11</Subscript>NO)<Subscript>4.5</Subscript>Н<Subscript>4</Subscript>[SiМо<Subscript>12</Subscript>O<Subscript>40</Subscript>]

New caprolactam dodecamolybdosilicate of the composition (C₆H₁₁NO)_4.5Н₄[SiМо₁₂O₄₀] (I) is synthesized. Chemical and crystallographic analyses, NMR and IR spectroscopic studies are performed. Compound I is found to crystallize in the monoclinic system with the space group P2₁/n. Unit cell parameters are: a = 19.945(4) Å, b = 13.340(3) Å, c = 28.110(6) Å, β = 110.75(3)°, ρ_calc = 2.232 g/cm³, М = 2350.63, Z = 4, V = 6994(3) ų.     

Gas-phase observation of the heterolytic dissociation of negative ions into counter ions: Dissociation of [Cu phthalocyanine (SO<Subscript>3</Subscript>)<Subscript>4</Subscript>Na]<Superscript>3−</Superscript>.

Ion pair formation proceeding in solution at room-temperature, where it is driven by energies of solvation, has been observed in the gas-phase in the collision-induced dissociation of [Cu phthalocyanine (SO3)4Na]3- and [Cu phthalocyanine (SO3)4Na2]2- at low energies. The gas-phase observation of these charge separations into positive and negative ions, seemingly counter-intuitive, is favored sufficiently by thermodynamics to proceed at low collision energies. The combination of a high stability of the negative product anion against electron detachment and a low recombination energy of the departing positive counter ion appears to be the key requirement for such dissociations to proceed at low energies in the gas-phase.     

Hydroethoxycarbonylation of α-olefins at low pressure of carbon(II) oxide in the presence of the PdCl<Subscript>2</Subscript>(PPh<Subscript>3</Subscript>)<Subscript>2</Subscript>–PPh<Subscript>3</Subscript>–AlCl<Subscript>3</Subscript> system

High catalytic activity of the PdCl₂(PPh₃)₂–PPh₃–AlCl₃ system containing AlCl3 as promotor has been demonstrated in the reaction of hydroethoxycarbonylation of hexene-1 and octene-1 at low pressure of carbon(II) oxide (≤25 atm). The reaction yields linear and branched products. The optimal conditions of the process have been elaborated. The target products yield is 84.6–93.8%.     

Synthesis of 5-<Emphasis Type="Italic">tert</Emphasis>-butyl-1,2,3-trimethylbenzene catalyzed by [Et<Subscript>3</Subscript>NH]Cl–AlCl<Subscript>3</Subscript>

Common Lewis acids and Lewis acidic ionic liquid catalysts were applied in the synthesis of 5-tert-butyl-1,2,3-trimethylbenzene from 1,2,3-trimethylbenzene and 2-chloro-2-methylpropane, where [Et₃NH]Cl–AlCl₃ demonstrated the most promising catalytic potential. The effects of reaction time, temperature, catalyst composition and dosage have been systematically studied in the presence of [Et3NH]Cl–AlCl3. The maximum selectivity of 90.32% was achieved upon heating at 10°C for 5 h with a mass fraction of [Et₃NH]Cl–AlCl₃ to 1,2,3-trimethylbenzene of 10%. Activity of the ionic liquid catalyst remained high after several cycles.     

Crystal structure of a trinuclear Zn(II) complex: [Zn<Subscript>3</Subscript>L<Subscript>2</Subscript>(μ<Subscript>1,1</Subscript>-N<Subscript>3</Subscript>)<Subscript>2</Subscript>I<Subscript>2</Subscript>] [l = 2-[(3-dimethylaminopropylimino) methyl]-6-ethoxyphenolate]

Reaction of zinc iodide, sodium azide and 2-[(3-dimethylaminopropylimino)methyl]-6-ethoxyphenol (HL) results in the formation of a trinuclear complex [Zn₃L₂(μ_1,1-N₃)₂I₂]. The complex is characterized by elemental analysis, IR spectroscopy, and X-ray crystallography. The complex possesses crystallographic two-fold rotation axis symmetry and crystallizes in the monoclinic system, C2/c space group, a = 23.241(2) Å, b = 10.849(1) Å, c = 17.384(2) Å, β = 120.868(1)°, V = 3762.4(6) ų, Z = 4. The molecule consists of two [ZnL(N₃)I] units connected together by a central Zn atom. The terminal Zn atom is fivecoordinated in a trigonal-bipyramidal geometry, and the central Zn atom is six-coordinated in an octahedral geometry. The Zn...Zn separation between the terminal and the central Zn atoms is 3.257(2) Å.     

Synthesis and Structure of the bismuth complex [Ph<Subscript>3</Subscript>PrP]<Stack><Subscript>4</Subscript><Superscript>+</Superscript></Stack>[Bi<Subscript>4</Subscript>I<Subscript>16</Subscript>]<Superscript>4−</Superscript>

The complex [Ph₃P] ₄ ⁺ [Bi₄I₁₆]^4? · 2 Me₂C=O (I) was synthesized by the reaction of triphenyl(propyl)phosphonium iodide with bismuth iodide in acetone. The crystal structure of complex I was determined by X-ray crystallography. It contains, in addition to solvent molecules, two types of crystallographically independent tetrahedral tetraphenyl(propyl)phosphonium cations and tetranuclear anions [Bi₄I₁₆]^4? in a chair conformation with the bismuth atoms being in an octahedral coordination. The Bi-I distances in the anion vary within 2.8768(4)–3.2524(4) Å.     

The hydrothermal synthesis and crystal structure of [2.2′-bipyH]<Subscript>3</Subscript>PW<Subscript>12</Subscript>O<Subscript>40</Subscript>

The title compound, [2.2′-bipyH]₃PW₁₂O₄₀, consists of three [2.2′-bipyH]⁺ and one Keggin structure heteropolyanion [PW₁₂O₄₀]^3?, which was hydrothermally synthesized and characterized by elemental analysis, IR spectra and single crystal X-ray diffraction. It belongs to triclinic system, space group P \(\bar 1\), a = 12.086(3) Å, b = 12.777(4) Å, c = 19.152(4) Å, α = 88.861(2)Å, β = 89.851(3)Å, γ = 67.034(3)Å, M = 3345.72 g/mol, V = 2722.6(12) ų, Z = 2, D _c = 4.081 mg/m³, R₁ = 0.0474, wR ₂ = 0.1135, T = 293(2) K. In this compound, each of the three H⁺ ions locates at between the N atoms in one 2.2′-bipy molecule, respectively. The protonated cations and the heteropolyanion effect each other by the electrostatic force.     

Thermodynamic characteristics of europium pivalate binuclear complexes Eu<Subscript>2</Subscript>(Piv)<Subscript>6</Subscript> and [Eu<Subscript>2</Subscript>(Piv)<Subscript>6</Subscript> · (Phen)<Subscript>2</Subscript>]

Sublimation of europium pivalate binuclear complexes Eu₂(Piv)₆ and [Eu₂(Piv)₆ · (Phen)₂] (Piv = (CH₃)₃CCOO, Phen = C₁₂H₈N₂) in the temperature range of 383–660 K is studied by the Knudsen effusion method with mass-spectrometric analysis of the gas phase. The vaporization of Eu₂(Piv)₆ is shown to be accompanied by polymerization and the formation of Eu₂(Piv)₆ and Eu₄(Piv)₁₂ molecules. The saturated vapor over the mixed-ligand complex of europium pivalate with o-phenanthroline consists of Phen, Eu₂(Piv)₆, and Eu₄(Piv)₁₂ molecules. The partial pressures of the gas components, as well as the standard enthalpies of sublimation and dissociation of the reaction proceeding with removal of phenanthroline have been determined.     

Motif of the three-layered close packing of cluster anions in [RhPy<Subscript>4</Subscript>Cl<Subscript>2</Subscript>]<Subscript>4</Subscript>[Re<Subscript>6</Subscript>S<Subscript>8</Subscript>(CN)<Subscript>6</Subscript>]·1.5H<Subscript>2</Subscript>O

[RhPy₄Cl₂]₄[Re₆S₈(CN)₆]·1.5H₂O (Py is pyridine) was investigated by X-ray analysis. In the cluster anion, the Re-Re distances vary from 2.6063(2) Å to 2.6125(2) Å. For two crystallographically independent complex cations, the distances are 〈Rh-N〉 2.060 Å and 〈Rh-Cl〉 2.336 Å. The motif of the three-layered close packing was found; the [Re₆S₈(CN)₆]^4? anions follow the vertices of a rhombohedron with the parameters a _c ≈ 15.5 Å and α_c ≈ 61°.     

The influence of the organolithium reagent nature on the possibility of the O→C<Subscript>sp</Subscript> migration of the R<Subscript>3</Subscript>Si group in propynes HC≡CCH<Subscript>2</Subscript>OSiR<Subscript>3</Subscript>

A possibility of the O→C_sp 1,4-migration of the R₃Si group in silyl ethers of terminal acetylenic alcohols upon treatment with organolithium reagents (RLi) was studied. In the case of 3-trimethylsilyloxypropyne, depending on the nature of RLi, the heterolysis of the Si—O bond occurs either by the action of acetylide formed as a result of deprotonation with the formation of 3-trimethylsilylprop-2-yn-1-ol trimethylsilyl ether, or by the action of the metalation agent with the formation of propargyl alcohol. The realization of the O→C_sp 1,4-migration of the Me₃Si group requires the use of mild organolithium reagents (lithium hexamethyldisilazanide and diisopropylamide). Silyl ethers having steric hindrance at the carbon atom bonded to the reaction center or around the silicon atom do not react with the studied organolithium reagents.