Kinetics of Isothermal Pyrolysis of Iodomethanes in the Gas Phase

The limiting step of the isothermal pyrolysis of gaseous iodomethane (CH₃I → 3/4CH₄ + 1/2I₂ + 1/(4n)C _n ) and diiodomethane (CH₂I₂ → 1/2CH₄ + I₂ + 1/(2n)C _n ) are the reactions 2CHI → C₂ + 2HI and 2CI₂ → C₂ + 2I₂, respectively. The rate constants of these reactions were determined.     

The inductive effect of a radical center and transferability of the properties of functional groups in <Emphasis Type="Italic">n</Emphasis>-alkyl radicals

Electron density distribution in n-alkyl radicals (from ethyl to n-octyl) was studied by the B3LYP/6-311++G(3df,3pd) DFT method. The theory of atoms in molecules was used to show that the inductive effect of a free valence extends to two neighboring CH₂ groups. The electronegativities χ(C^?H₂) > χ(CH₃) > χ(CH₂) of groups and χ(C^?) > χ(H) > χ(C) atoms were qualitatively determined. The group method for calculating the enthalpies of formation of n-alkyl radicals Δ_f H°(n-C _n H_{2n+ 1}, n > 5) was substantiated.     

Determination of the molecular masses of tetrafluoroethylene telomers by gel-permeation chromatography

Gel-permeation chromatography has been employed to study the molecular-mass distribution of tetrafluoroethylene telomers prepared through γ irradiation of 0.05–0.56 mol/l monomer solutions in acetone. The molecular-mass-retention-volume V _R calibration dependence has been plotted from chromatograms of perfluoroenanthic and perfluoropelargonic acids (F(CF₂-CF₂) _n COOH; n = 3 or 4, respectively). The measured V _R-log n curve is located parallel to that plotted earlier for oligo(oxyethylene glycol)s (OH-(CH₂-CH₂O) _n -OH) and is shifted along the volume axis. The shift value is determined by the ratio between logarithmic volumes of chain units of these oligomers. The shift agrees with the assumption that the retention volumes of oligomers with the same spatial chain structure are proportional to the logarithm of the ratio between their van der Waals volumes. This assumption is supported by the quantum-chemical calculation of the molecular volumes of oligomers composed of (CH₂-CH₂) _n , (CH₂-CH₂O) _n , and (CF₂-CF₂) _n fragments. As the concentration of tetrafluoroethylene in the initial solution is increased, the average length of (CF₂-CF₂) _n chains increases from \(\bar n\) ≈ 3 to \(\bar n\) ≥ 8. The maximum values of n = 12–15 are determined by the solubility limit of telomers in THF.     

Extraction Properties of Oligoethylene Glycol Bis[(2-Diphenylphosphinylmethyl-4-methyl)phenyl] Ethers

Extraction of Ln(III), Sc(III), Ga(III), and Re(VII) ions by solutions of phosphorylated monopodands having [ortho-(diphenylphosphinylmethyl)-para-methyl]phenyl terminal groups, 2-Ph₂P(O)CH₂(4-Me)C₆H₃(OCH₂CH₂) _n OC₆H₃(Me-4)CH₂P(O)Ph₂-2 (n = 1–5), in organic solvents has been studied. The stoichiometries of extractable complexes were determined. The effect of the aqueous phase, organic solvent, and phosphorylated podand structure on the efficacy of metal-ion recovery into organic phase has been considered.     

Crystal structure of dimethylgold(III) 8-hydroxyquinolinate and 8-mercaptoquinolinate

A crystal-chemical study of dimethylgold(III) complexes with 8-hydroxyquinoline (CH₃)₂Au(OR) and 8-mercaptoquinoline (CH₃)₂Au(SR) (R = C₉H₆N) was performed. Crystal data for (CH₃)₂Au(OR): a = 8.7133(17) Å, b = 27.875(6) Å, c = 8.6688(17) Å, β = 102.76(3)°, Z = 8, ρ(calc) = 2.401 g/cm³, space group P2₁/c, R = 0.0909; for (CH₃)₂Au(SR): a = 3.5401(7) Å, b = 15.689(3) Å, c = 19.910(4) Å, β = 99.81(3)°, Z = 4, ρ(calc) = 2.361 g/cm³, space group P2₁/c, R = 0.0712. Both structures are molecular and involve neutral (CH₃)₂Au(L) molecules, L = C₉H₆NO or C₉H₆NS. In the structures, the molecules are arranged in stacks joined by van der Waals interactions. The average Au…Au intrastack distances are 3.57 Å and 4.34 Å for (CH₃)₂Au(OR) and 3.5 Å for (CH₃)₂Au(SR).     

New derivatives of 4-quinaldinol

The reactions of 1, 1, 3-trichloro-1-propene and also 1, 1, 1-trichloro-2-propene with acetoacetic ester gave α-(γ, γ-dichlorallyl)acetoacetic ester (I). In the reactions with aniline and o- and p-toluidines, the corresponding α-(γ, γ-dichloroallyl)-β-arylamino-crotonic esters were produced, thermal cyclization of which gave 2-methyl-3-(γ, γ-dichloroallyl)-4-hydroxyquinoline (II) and its 6CH₃- (III) and 8CH₃- (IV) homologs. With phosphorus oxychloride, II–IV gave the corresponding 4-chloro-substituted quinolines (V–VII); with concentrated sulfuric acid, II–VII were converted into the corresponding β-quinolinylpropionic acids VIII–XIII.     

Synthesis and crystal structure of the equimolar complex of copper(I) cyanide with 3,3′-[ethane-1,2-diylbis(oxy)]dipropanenitrile

Complex [Cu(CN)(NC(CH₂)₂O(CH₂)₂O(CH₂)₂CN))] is obtained by the heating of copper(I) cyanide with 3,3′-[ethane-1,2-diylbis(oxy)]dipropanenitrile (DPN) followed by slow cooling. The X-ray diffraction analysis shows that the crystals are monoclinic, space group C2/c, a = 12.183(2), b = 10.667(2), c = 8.4700(13) Å, β = 92.444(10)°, V = 1099.7(3) ų, Z = 4. The structure is built of infinite zigzag fragments [Cu(CN)(DPN)] _n . The tetrahedral environment of the copper atom includes two cyano groups of the ligand and two cyano groups of the inorganic fragment.     

Mononuclear cobalt (III) complexes with <Emphasis Type="Italic">N</Emphasis>-salicylidene-2-hydroxy-5-bromobenzylamine and <Emphasis Type="Italic">N</Emphasis>-salicylidene-2-hydroxy-5-chlorobenzylamine

Cobalt (III) complexes with N-salicylidene-2-hydroxy-5-bromobenzylamine (H₂sbba) and N-salicylidene-2-hydroxy-5-chlorobenzylamine (H₂scba), [n-(C₄H₉)₄N][Co(sbba)₂] (I) and [n-(C₄H₉)₄N][Co(scba)₂] (II), were synthesized. The crystal structure of II was determined by the single-crystal X-ray diffraction method at 90 K confirming its crystallization in the monoclinic space group P2₁/n with a = 11.729(2) Å, b = 16.901(3) Å, c = 21.483(4) Å, β = 98.840(4)°, V = 4208.2(14) ų, D_x = 1.295 g cm^?3, and Z = 4. The R1 [I > 2σ(I)] and wR2 (all data) values of 0.0664 and 0.1920, respectively, for all 9521 independent reflections. The compound is composed of a tetra(n-butyl)ammonium cation and an octahedral cobalt(III) complex anion with two scba^2? ligands in a meridional fashion. The electronic spectral features of I and II are consistent with the octahedral cobalt(III) ion with an N₂O₄ donor set.     

Polycatenate Structure and Thermal Analysis of a New 2D + 2D Cobalt(II) Coordination Polymer Based on 5-Methoxylisophthalic Acid and 3,5-Bis(imidazole-1-yl)pyridine Co-Ligands

A new Co(II) compound, namely [Co(CH₃O-H₂Ip)(Bip)] _n (I) (CH₃O-H₂Ip = 5-methoxylisophthalic acid and Bip = 3,5-bis(imidazole-1-yl)pyridine), has been synthesized through combination of CH₃O-H₂Ip, Bip and Co(II) acetate under hydrothermal condition and structurally characterized by IR spectroscopy, elemental analysis and single-crystal X-ray diffraction (CIF file CCDC no. 977220). It crystallizes in triclinic, space group P1? with a = 9.764(6), b = 10.106(6), c = 11.673(7) Å, α = 104.12970°, β = 100.601(7)°, γ = 105.324(7)°, V = 1038.6(11) ų, C₂₀H₁₆CoN₅O₅, Mr = 465.31, Z = 2, ρ_calcd = 1.488 g/cm³, μ(MoK_α) = 0.869 mm^?1, F(000) = 476, the final R = 0.0652 and wR = 0.1530. The X-ray analysis demonstrates that compound I exhibits a 2D + 2D polyrotaxane (4, 4) net network. Moreover, the thermal analysis of compound I has also been investigated.     

Synthesis and structure of Pt(II) acetamidate complexes containing <Emphasis Type="Italic">N</Emphasis>,<Emphasis Type="Italic">N</Emphasis>-dimethyl-substituted ethylenediamine and trimethylenediamine

Reactions of acetamide with platinum(II) diamines [Pt(N,N-DimeEn)Cl₂], [Pt(Tm)Cl₂], and [Pt(N,N-DimeTm)Cl₂] (N,N-DimeEn = (CH₃)₂N(CH₂)₂NH₂, Tm = NH₂(CH₂)₃NH₂, N,N-DimeTm = (CH₃)₂N(CH₂)₃NH₂) with preliminary precipitation of chlorine ions by silver salts gave binuclear Pt(II) acetamidates [Pt₂(CH₃)₂N(CH₂)₂NH₂)₂(μ-NHCOCH₃)₂](NO₃)₂ · H₂O (I), [Pt₂(NH₂(CH₂)₃NH₂)₂)(μ-NHCOCH₃)₂](NO₃)₂ · H₂O (II), and [Pt₂(CH₃)₂N(CH₂)₃NH₂)₂(μ-NHCOCH₃)₂](HSO₄)₂ (III), whose crystal structures were determined. Crystals of I are monoclinic: a = 14.459(2) Å, b = 17.197(3) Å, c = 9.822(2) Å, β = 105.923(10)°, V = 3348.6(8) ų, space group P2(1)/c, Z = 4, R _hkl = 0.0419 for 6663 reflections. Complex I is a binuclear acetamidate with bridging (NHCOCH₃)^? ligands, one of which is bound to two Pt atoms through the N and O atoms, and the other ligand is bound only through the N atom. The Pt-Pt distance is 2.987(1) Å. Crystals of II are monoclinic: a = 10.213(7) Å, b = 13.373(9) Å, c = 16.533(11) Å, β = 97.971(9)°, V = 2236(3) ų, space group P2(1)/n, Z = 4, R _hkl = 0.557 for 6462 reflections. The Pt-Pt distance is 3.057(1) Å. Crystals of III are monoclinic: a = 10.557(12) Å, b = 18.531(2) Å, c = 14.4744(17) Å, β = 108.705(2)°, V = 2682(5) ų, space group P2(1)/n, Z = 4, R _hkl = 0.569 for 8506 reflections. The Pt-Pt distance is 3.202(1) Å. Complexes II and III are binuclear acetamidates, in which two chelating Pt(Tm) or Pt(N,N-DimeTm) moieties are coordinated through the N and O atoms of (NHCOCH₃)^? cis-bridges.     

Synthesis of Polyfluorinated Ethers

Procedures for preparing polyfluorinated ethers H(CF₂CF₂) _n CH₂OR by alkylation of the corresponding telomeric alcohols H(CF₂CF₂) _n CH₂OH (n = 1–3) with alkyl halides and alkyl tosylates were examined.     

Exact treatment of generalized modifications of finite-dimensional systems by the LRM approach

LRM (Low Rank Modification) is a mathematical method that produces eigenvalues and eigenstates of generalized eigenvalue equations. It is similar to the perturbation expansion in that it assumes the knowledge of the eigenvalues and eigenstates of some related (unperturbed) system. However, unlike perturbation expansion, LRM produces correct results however large the modification of the original system. LRM of finite-dimensional systems is here generalized to the combined (external and internal) modifications. Parent n-dimensional system A _n containing n eigenvalues λ _i and n eigenstates \({| {\Phi_i}\rangle}\) is described by the generalized n × n eigenvalue equation. In an external modification system A _n interacts with another ρ-dimensional system B _ρ which is situated outside the system A _n . In an internal modification relatively small σ-dimensional subsystem of the parent system A _n is modified. Modified system C _n+ρ that contains external as well as internal modifications is described by the generalized (n + ρ) × (n + ρ) eigenvalue equation. This system has (n + ρ) eigenvalues \({\varepsilon_s}\) and (n + ρ) corresponding eigenstates \({| {\Psi_s}\rangle}\) . In LRM this generalized (ρ + n) × (ρ + n) eigenvalue equation is replaced with a (nonlinear) (ρ + σ) × (ρ + σ) equation which produces all eigenvalues \({\varepsilon_s \notin \left\{ {\lambda_i}\right\}}\) and all the corresponding eigenstates \({| {\Psi_s}\rangle }\) of C _{n + ρ}. Another equation produces remaining solutions (if any) that satisfy \({\varepsilon_s \in \left\{ {\lambda_i}\right\}}\) . Those two equations produce exact solution of the modified system C _{n + ρ}. If (ρ + σ) is small with respect to n, this approach is numerically much more efficient than a standard diagonalization of the original generalized eigenvalue equation. Unlike perturbation expansion, LRM produces exact results, however large modification of the parent system A _n .     

Crystal structures of tetrafluoroantimonates(III) of single and double protonated 3-amino-1,2,4-triazolium cations

Crystal structures are determined by X-ray crystallography for tetrafluoroantimonates(III) of single and double protonated 3-amino-1,2,4-triazolium cations of the composition (C₂H₅N₄)SbF₄ (I) (monoclinic: a = 4.7723(6) Å, b = 19.643(2) Å, c = 7.6974(9) Å, β = 97.239(2)°, Z = 4, Cc space group) and (C₂H₆N₄)(SbF₄)₂ (II) (monoclinic: a = 4.7617(3) Å, b = 15.512(1) Å c = 7.4365(5)Å β = 107.706(1)°, Z = 2, P2₁/n space group). The structure of I is built from complex [SbF₄]^? anions and single charged (C₂H₅N₄)⁺ cations; the structure of II is built from the same anion and double charged 3-amino-1,2,4-triazolium cation: (C₂H₆N₄)²⁺. In the structure, weak interactions Sb…F join the anions in polymeric layers [SbF₄] _n ^n? that are assembled in a 3D framework by N-H…F hydrogen bonds. The formation of the double protonated 3-amino-1,2,4-triazolium cation (C₂H₆N₄)²⁺, found in the crystal structure of II, is observed for the first time.     

Processes of hydrogenation of trifluoromethylfullerenes in the mass spectrometer ion source

The processes of hydrogenation of a mixture of trifluoromethylfullerenes was studied in situ by means of positive-and negative-ion mass spectrometry. The effective addition of 1, 5, and 11 hydrogen atoms was revealed. The appearance energies of positive trifluoromethylfullerene ions C ₆₀ (CF₃) _n ⁺ (n = 1–8) and C₆₀(CF₃) _n H⁺ (n = 1, 3, 5, 7) were determined.     

Hydrothermal synthesis and crystal structure of a new 3<Emphasis Type="Italic">d</Emphasis>–4<Emphasis Type="Italic">f</Emphasis> complex generated from the IDA ligand

An interesting 3d–4f complex [CeCo(HIDA)(IDA)₂] _n (I) (IDA = iminodiacetic acid) was synthesized under hydrothermal conditions and characterized by IR, TG, and single-crystal X-ray diffraction analysis. Complex I crystallizes in the monoclinic system, space group C2/c with a = 9.7033(19), b = 24.141(5), c = 8.5810(17) Å, β = 115.01(3)°, V = 1821.6(6) ų, Z = 4, ρ _c = 2.152 g/cm³, F(000) = 1148. Crystallographic data for I were collected at 293 K with a Rigaku R-axis Rapid IP diffractometer using graphite monochromatic MoK _α radiation (λ = 0.71073 Å) and IP technique, GOOF = 0.994, the final R = 0.0245 and wR = 0.0763 (I > 2σ(I)). Complex I is a two-dimensional layer structure, in which the Ce(III) center is surrounded by ten oxygen atoms from different IDA ligands. The Co(II) center is six-coordinated by four oxygen atoms and two nitrogen atoms from two different IDA ligands. The carboxylic oxygen atom connected such units along the z axis to form a one-dimensional chain-like structure. The IDA ligand connects neighboring chains to form a two-dimensional layer structure.     

One-dimensional cyanide-bridged Cr(III)–Cu(II) complexes: synthesis,crystal structures and magnetic properties

Using two trans-dicyanidechromium(III) precursors K[Cr(bpdmb)(CN)₂] (bpdmb^2? = 1,2-bis(pyridine-2-carboxamido)-4,5-dimethyl-benzenate), K[Cr(bpClb)-(CN)₂] (bpClb^2? = 1,2-bis(pyridine-2-carboxamido)-4-chloro-benzenate) and one Cu(II) complex of a 14-membered macrocycle as ancillary organic ligand as assembling segments, two one-dimensional cyanide-bridged Cr^III–Cu^II complexes {{[Cu(cyclam)][Cr(bpdmb)(CN)₂]}ClO₄} _n ·nCH₃OH·nH₂O (1) and {{[Cu(cyclam)][Cr(bpClb)(CN)₂]}ClO₄} _n ·nCH₃OH (2) (cyclam = 1,4,8,11-tetraazacyclotetradecane) have been synthesized and characterized by elemental analysis, IR spectroscopy and X-ray structure determination. Single X-ray diffraction analysis shows that their similar one-dimensional cationic single-chain structures consist of alternating units of [Cu(cyclam)]²⁺ and [Cr(bpdmb)(CN)₂]^?/[Cr(bpClb)(CN)₂]^? with free ClO₄ ^? as balancing anions. Investigations of the temperature dependences of magnetic susceptibility and the field-dependent magnetization reveal that both complexes have overall ferromagnetic coupling between the neighboring Cr(III) and Cu(II) centers through the bridging cyanide groups.     

Special Features of the Interaction between Asymmetric Dimethylhydrazine and Thiocontaining Schungite

The interaction between asymmetric dimethylhydrazine and thiocontaining mineral schungite-III has been studied. Chromatography–mass spectrometry has been used to identify alkyl polysulfides as the products of desorption of asymmetric dimethylhydrazine from schungite surface. The interaction of asymmetric dimethylhydrazine with crystalline sulfur has been investigated in a model system. Dimethyl polysulfides, CH₃S_nCH₃; (dimethylamino)methyl polysulfides, (CH₃)₂NS_nCH₃; and bis(dimethylamino) polysulfides, (CH₃)₂NS_nN(CH₃)₂, with 2 ≤ n ≤ 4 have been detected. Gas-chromatographic retention indices have been determined for the products of the interaction of asymmetric dimethylhydrazine with sulfur and the schungite material.     

Synthesis and crystal structure of two derivatives of benzodiazepines

Two benzodiazepine derivatives, C₂₃H₂₂N₂O (I), 2-methyl-8-methoxy-2,4-diphenyl-2,3-dihydro-1H-1,5-benzodiazepine, and C₂₂H₁₇N₃O₂Br₂ (II), 2-methyl-7-nitro-2,4-bis(4′-bromophenyl)-2,3-dihydro-1H-1,5-benzodiazepine, were studied by single crystal X-ray diffraction method. Compound (I) crystallizes in the monoclinic system, space group P2₁/c, a = 13.1703(17) Å, b = 11.1990(14) Å, c = 12.9093(16) Å, β = 107.831(2)°, V = 1812.6(3) ų, Z = 4. Compound (II) crystallizes in the monoclinic system, space group P2₁/n, a = 11.7345(12) Å, b = 12.7477(13) Å, c = 13.5965(14) Å, β = 95.221(2)°, V = 2025.4(4) ų, Z = 4. The molecules of (I) and (II) have T-shape form with the diazepine ring at the junction point. The seven membered central benzodiazepine ring in both structures adopt a twist-boat conformation. The crystal packing is stabilized by C-H…π (in I) and C-H…O (in II) interactions.     

Crystal structures of 1,1,1-trifluoro-4-hydroxy-4-phenyl-but-3-en-2-one, 2,2,6,6-tetramethyl-3-hydroxy-hept-3-en-5-one, 2,2,6,6-tetramethyl-3-methylamino-hept-3-en-5-one and a study of the ability of these ligands to complex formation with metals

Crystal structures are determined (Bruker Nonius X8 Apex, 4K CCD-detector, λMoK _α, graphite monochromator, T 150 K and 293 K) for two β-diketones F₃CC(O)CH₂C(O)Ph (1) (space group P2₁/c, a = 7.0713(3)Å, b = 11.5190(6)Å, c = 11.3602(6) Å, β = 99.405(2)°, V = 912.90(8) ų, Z = 4), (CH₃)₃CC(O)CH₂C(O)C(CH₃)₃ (2) (space group Pbca, a = 11.5536(8) Å, b = 11.5796(10) Å, c = 17.2523(13) Å, V = 2308.1(3) ų, Z = 8) and a ketoimine (CH₃)₃CC(NCH₃)CH₂C(O)C(CH₃)₃ (3) (space group I4₁/a, a = 18.7687(6) Å, b = 18.7687(6) Å, c = 14.5182(6) Å, V = 5114.2(3) ų, Z = 16). All structures are molecular and comprise isolated molecules joined by van der Walls interactions. The substitution energy of a Na atom for a hydrogen atom in free ligands is calculated by the hybrid B3LYP quantum chemical method. A successful preparation of Na(I) chelates with ligands 1, 2 and failed attempts to prepare a complex with ligand 3 are in accordance with the calculations. Geometrical simulation of a copper(II) complex with ligand 3 reveals the overlap of CH₃ groups which hinders the complexation.     

Synthesis and crystal structure of dimethylgold(III) carboxylates

Three novel carboxylate complexes were synthesized: dimethylgold(III) trifluoroacetate [Me₂Au(Tfa)]₂ (I), trimethylacetate (pivalate) [Me₂Au(Piv)]₂ (II), and benzoate [Me₂Au(OBz)]₂ (III). The starting reagent was [Me₂AuI]₂. The procedure of its synthesis provides 60% product yield. Dimethylgold(III) carboxylates were identified from the IR and ¹H NMR data. The title compounds were studied by X-ray diffraction. The unit cell parameters for I, C₈H₁₂Au₂F₆O₄: a = 15.5522(13), b = 12.9398(11), c = 15.6555(14) Å, β = 104.308(2)°, Z = 8, ρ(calcd.) = 2.959 g/cm³, space group C2/c, R = 0.0779; for II, C₁₄H₃₀Au₂O₄: a = 10.3025(3), b = 15.5952(4), c = 12.6819(3) Å, β = 105.8270(10)°, Z = 4, ρ(calcd.) = 2.224 g/cm³, space group P2₁/c, R = 0.0229; for III, C₁₈H₂₂Au₂O₄: a = 12.8050(2), b = 19.7886(3), c = 7.60300(10) Å, Z = 4, ρ(calcd.) = 2.401 g/cm³, space group Pnma, R = 0.0144. Compounds I–III have the molecular structures; the structural units are the [(CH₃)₂Au(OOCR)]₂ dimers (Au…Au 2.984–3.080 Å), R = CF₃, tert-Bu, Ph. The gold atoms have the square coordination with two carbon atoms and two oxygen atoms (Au-O 2.120–2.173 Å). The molecules in compounds I–III are united into infinite unidimensional chains connected by van der Waals interactions.