Composition and structure of heteroassociates formed in a binary liquid system HF-CH<Subscript>3</Subscript>CN

The concentration dependence of normalized absorbance (to the total number of moles of components in one liter) of HF solutions in acetonitrile (1:12–10:1) is analyzed. It is found that in the binary liquid system (BLS) under study molecular complexes with stoichiometric 1:1 and ～10:1 ratios of molecules occur along with the heteroassociates (HAs) found previously with the ratio HF:CH₃CN of 4:1. For each of the HAs the concentration range at which it is formed in BLS is evaluated, and the positions of HF stretching vibrational bands are found. Optimum configurations and vibrational frequencies of molecular complexes (HF) _m ·(CH₃CN) _n (m = 1–6, n = 1–2) of various topology are calculated using the density functional method (B3LYP/6-31 ++ G (d, p)). Their relative stability and the structure peculiarities are studied; complexation tendencies in the HF-CH₃CN system are revealed. The structure of HAs with 1:1 and 4:1 stoichiometric ratios of molecules is determined by comparing the results of calculations and experiment.     

Structure of heteroassociates formed in the HF-(C<Subscript>2</Subscript>H<Subscript>5</Subscript>)<Subscript>2</Subscript>O liquid system

The aim of this work was to determine the structure of stable heteroassociates (HAs) with the stoichiometric ratios 1:2, 2:1, and 4:1 of molecules formed in the HF-(C₂H₅)₂O binary liquid system. The stretching frequencies of HF molecules found for each HA using a special procedure for processing IR spectra were compared with the calculated frequencies V HF of the stable molecular complexes (HF)_m ((C₂H₅)₂O)_n (m = 1, 2, 4, 8; n = 1, 2) with different topologies by the density functional method (B3LYP/6-31++G(d,p)). As a result, it was shown that the most stable (among H-bonded complexes with the same stoichiometric ratio of molecules) HAs HF((C₂H₅)₂O)₂, (HF)₄ ((C₂H₅)₂O)₂, and (HF)₈-((C₂H₅)₂O)₂ formed in HF solutions in diethyl ether. All of them had a cyclic structure and a common peculiarity of structure: only one lone electron pair of the oxygen atom of the (C₂H₅)₂O molecules is involved in hydrogen bonding.     

Direct Mass Spectrometric Study of the Ionic Species Content of a C<Subscript>2</Subscript>HCl<Subscript>3</Subscript>/He/O<Subscript>2</Subscript> Microwave Discharge Plasma

Direct on-line studies of a C₂HCl₃/He/O₂ microwave discharge plasma made possible the evolution and detection of many unfamiliar ionic species. Numerous ionic chlorocarbons, chlorohydrocarbons, oxygenated chlorohydrocarbons, oxygenated hydrocarbon radicals, and simple hydrocarbon species were identified mass spectrometrically as by-products: C _m Cl _n (m = 1–4, 6, 8; n = 1–8), C _m H _n Cl _x (m = 1–4, 6, 7, 10; n, x = 1–6), C _m H _n Cl _x O _y (m = 1–5, 12; n = 1–7; x = 1, 2, 4, 6; y = 1–3), C _n H_2n−1O (n = 2, 3), C _m H _n (m = 2, 4, 6, 8; n = 2, 4), and so on. The studies clearly showed the presence of various unfamiliar positive ionic O-containing species such as C₂ClO₂, CCl₃CO, C₂H₂Cl₄O₂, and C₄H₂Cl₆O₃. It is apparent that positive-ion reactions play a significant role in producing many ionic species in the chemistry of C₂HCl₃ plasmas.     

Phase equilibriums,ion association,and mechanisms of solvation in the LiN(CF<Subscript>3</Subscript>SO<Subscript>2</Subscript>)<Subscript>2</Subscript>-(CH<Subscript>3</Subscript>)<Subscript>2</Subscript>SO<Subscript>2</Subscript> system

The phase diagrams, isotherms of the electrical conductivity, Raman spectra, and time correlation functions of vibrational dephasing are studied for the LiN(CF₃SO₂)₂-(CH₃)₂SO₂ system, which is promising for use as an electrolyte in medium-temperature lithium-ion batteries. The phase diagram of this system contains a broad supercooled region. It is shown that the concentration dependences of the electrical conductivity are typical for solutions of strong electrolytes. The Raman spectra and the time correlation functions of vibrational dephasing for the anion and the solvent indicate that in the supercooling range, cations are weakly solvated by solvent molecules and form ion pairs.     

Reaction of the novel Ru<Subscript>3</Subscript>(CO)<Subscript>10</Subscript>[Ph<Subscript>2</Subscript>P(CH<Subscript>2</Subscript>)<Subscript>2</Subscript>Si(OEt<Subscript>3</Subscript>)]<Subscript>2</Subscript> complex on SBA-15 and MCM-41 mesoporous silicas

The reaction of Ru₃(CO)₁₂ with 2(diphenylphosphino)ethyl-triethoxysilane (DPTS) in hydrocarbons, leads to the functionalized Ru₃(CO)_12−n [Ph₂P(CH₂)₂Si(OEt₃)] _n (n = 1,2) complexes. The complex with two phosphine substituents was chemically anchored on mesoporous silicas, SBA-15 and MCM-41, in order to obtain two hybrid materials characterized by a different localization of the metal centre on the surface of the porous supports. A detailed investigation of the cluster, before and after chemical anchoring on the mesoporous silicas, was pursued. Particular attention was also devoted to the study of the morphological, structural and textural properties of the metal-functionalised silicas (Ru/SBA-15 and Ru/MCM-41) by infrared spectroscopy (FT-IR), scanning electron microscopy, X-ray diffraction and N₂ physisorption analysis.     

Raman spectroscopic study of the hydration of short-chain poly(oxyethylene)s C <Subscript>1</Subscript>E<Subscript><Emphasis Type="Italic">n</Emphasis></Subscript>C <Subscript>1</Subscript> (<Emphasis Type="Italic">n</Emphasis>=1−4)

The hypothesis that the degree of hydration of poly(oxyethylene) (POE) in aqueous solution depends on the mole ratio of water molecules to ether oxygen atoms in the molecule has been verified by studying the isotropic Raman spectra in the O−H stretching region for four short-chain POEs (C ₁E _n C ₁ withn=1−4). Excellent coincidence of the O−H stretching Raman band for all four POEs studied in the range of mole ratio H₂O/O _ether from 25 to 0.6 was observed, thus confirming the assumption stated above. A conclusion that all ether oxygen atoms in the POE molecule participate in hydrogen bonding with water molecules has been made.     

Thermodynamic aspect of reversible structural conversion induced by guest adsorption/desorption based on infinite Co(NCS)<Subscript>2</Subscript>Py<Subscript>4</Subscript> (<Emphasis Type="Italic">Py</Emphasis>=pyridine) system

Summary Thermogravimetry (TG) and Me₂CO adsorption measurements for flexible porous crystalline coordination polymers with 2-dimensional (2-D) frameworks, {[Co(NCS)₂(3-pia)₂]·4Me₂CO}_n (1⊃4Me₂CO, 3-pia=N-(3-pyridyl)isonicotinamide), were carried out. Taking advantages of capability of hydrogen bonding of amide groups for a dynamic properties, 1⊃4Me₂CO show crystal (non-porous)-to-crystal (porous) structural rearrangement in Me₂CO adsorption/desorption processes. The activation energy for the Me₂CO desorption process of 1⊃4Me₂CO was obtained using Flynn-Wall-Ozawa’s (FWO) method. The Me₂CO adsorption isotherms on 1 have a threshold pressure (P_th) for abrupt accommodation of Me₂CO molecules, which is regarded as the equilibrium pressure for the inclusion reaction of Me₂CO     

The Reactions of Two New Alkoxy-silyl Functionalized Alkynes with M<Subscript>3</Subscript>(CO)<Subscript>12</Subscript> {M = Fe,Ru} and Co<Subscript>2</Subscript>(CO)<Subscript>8</Subscript>. Spectroscopic Identification of the Products

The new alkoxysilyl-functionalized alkynes [HC≡CCH₂N(H)C(=O)N(H)(CH₂)₃Si(OEt)₃] and [HC≡C(C₆H₄)–N(H)C(=O)N(H)(CH₂)₃Si(OEt)₃] have been synthesized using literature methods. These have been reacted with Fe₃(CO)₁₂, Ru₃(CO)₁₂ and Co₂(CO)₈. With the iron carbonyl only decomposition was observed: with Ru₃(CO)₁₂ splitting of the alkynes into their parent components and formation of the complexes (μ-H)Ru₃(CO)₉[HC=N(CH₂)₃Si(OEt)₃], (μ-H)Ru₃(CO)₉[C–C(C₆H₄)NH₂] and (μ-H)₂Ru₃(CO)₉[HC–CCH₃] occurred. Finally, with Co₂(CO)₈ formation of complexes Co₂(CO)₆(HC₂R) R=(C₆H₄)NH₂, CH₂NH(CO)NH(CH₂)₃Si(OEt)₃, (C₆H₄)NH(CO)NH(CH₂)₃Si(OEt)₃ containing the intact alkynes could be obtained.     

Structures and mutual transformations of isomers of germylium ions (CH<Subscript>3</Subscript>)H<Subscript>2</Subscript>Ge<Superscript>+</Superscript> and (CH<Subscript>3</Subscript>)<Subscript>2</Subscript>HGe<Superscript>+</Superscript> and their silicon analogs

The potential energy surfaces of the (CH₃)_nH_3?n M⁺ ions, where n = 1, 2; M = Si, Ge, were scanned using the B3LYP method with 6–31G* and aug-cc-pVDZ basis sets. The major attention was given to isomeric species having the form of complexes of the HM⁺ and CH₃M⁺ ions with hydrogen, methane, and ethane molecules. These species were characterized previously neither by experimental nor by theoretical methods. It was found that these species become more stable in going from Si to Ge; the complex [CH₃Ge⁺CH₄] is the second isomer in the energy after (CH₃)₂HGe⁺. However, the heights of the activation barriers to formation of these complexes from the most stable isomer, though decreasing in going from Si to Ge, remain relatively high and, what is particularly important, somewhat exceed the activation barrier to formation of the complex [H₃Ge⁺·C₂H₄].     

Synthesis and magnetic properties of quasi-unidimensional oxide Sr<Subscript>6.3</Subscript>Rh<Subscript>2.35</Subscript>Mn<Subscript>2.35</Subscript>O<Subscript>15</Subscript>

Attempts of the synthesis in air of complex oxides Sr₃RhMnO_x and Sr₄Rh_1.5Mn_1.5O_x resulted in revealing formation of a new oxide phase Sr_6.3Rh_2.35Mn_2.35O₉ related to quasi-unidimensional family A_3n+3m A′ _n B_3m+n O_9m+6n at n = 1 and m = 1. Its structural characteristics and magnetic properties are studied. X-ray data of the obtained phase is indicated on the basis of trigonal cell (spatial group P321) with the parameters: a 9.6239(4) Å; c ₁ 4.1130(4) Å, c ₂ 2.4946(2) Å. Manganese and rhodium exist in the compound as the cations Mn⁴⁺, Rh³⁺ and Rh⁴⁺, as follows from the data of measuring of magnetic susceptibility in the range 2–300 K.     

Multifunctional iron thiocarboxylate complexes: synthesis,reactivity and structure of CpFe(CO)<Subscript>2</Subscript>SCO-3,5-C<Subscript>6</Subscript>H<Subscript>4</Subscript>(COCl)<Subscript>2</Subscript>

A controlled substitution reaction of the chlorine atoms of 1,3,5-benzenetricarbonyl trichloride by the organoiron fragment (CpFe(CO)₂S) has been achieved. The complexes CpFe(CO)₂SCO-3,5-C₆H₃(COCl)₂ (1), 1,3-[CpFe(CO)₂SCO]₂-5-C₆H₃COCl (2) and 1,3,5-[CpFe(CO)₂SCO]₃C₆H₃ (3) were prepared from the reaction of (μ-S _x )[CpFe(CO)₂]₂ (x = 3, 4) with 1,3,5-C₆H₃(COCl)₃ in a 1:1, 2:1, or 3:1 metal to ligand molar ratio. The reactions of (1) with amines, thiols, and carboxylic acids produce the trifunctional mono-iron complexes CpFe(CO)₂SCO-3,5-C₆H₃(COY)₂ [Y = NR₂ (4), SR (5), OCOR (4)]. The X-ray structure determination of (1) is reported.     

Structure of palladium(I) carbonylcarboxylate clusters [Pd<Subscript>2</Subscript>(CO)<Subscript>2</Subscript>(RCOO)<Subscript>2</Subscript>]<Subscript><Emphasis Type="Italic">n</Emphasis></Subscript> in solution: NMR and IR study

The structures of palladium carbonylcarboxylate clusters [Pd₂(CO)₂(RCOO)₂] _n (n = 2, R = CH₃, CH₂Cl, CF₃, n = 3, R = CMe₃, CHMe₂, n-C₅H₁₁) are studied in benzene and tetrahydrofuran solutions by IR and ¹H and ¹³C NMR spectroscopy. The clusters in the solid state have a planar cyclic metal framework with pairs of the carbonyl and carboxylate ligands alternately coordinated on its sides. In solutions, compounds under consideration contain one-type carbonyl ligands and one-type carboxylate ligands; their structures are similar to thaso in the solid state.     

Effect of Pt nanoparticle size on the specific catalytic activity of Pt/SiO<Subscript>2</Subscript> and Pt/TiO<Subscript>2</Subscript> in the total oxidation of methane and <Emphasis Type="Italic">n</Emphasis>-butane

The dependence of the specific catalytic activity (A _sp ) of the catalysts Pt/SiO₂ and Pt/TiO₂ in the total oxidation of CH₄ and n-C₄H₁₀ on the Pt nanoparticle size (in the range from 1 to 4 nm) was studied. The specific catalytic activity increases with an increase in the platinum nanoparticle size, indicating that the total oxidation is a structure-sensitive reaction. The structure sensitivity depends on the size of an oxidized molecule: it increases sharply on going from CH₄ to n-C₄H₁₀. The support also exerts a considerable effect on the A _sp value: in the oxidation of both CH₄ and C₄H₁₀ the specific catalytic activity for the catalysts Pt/TiO₂ is 3–4 times that for Pt/SiO₂.     

Studies on the copolymerization of norbornene with CO catalyzed by a new catalytic system PdCl<Subscript>2</Subscript>/phen/M(CF<Subscript>3</Subscript>SO<Subscript>3</Subscript>)<Subscript>n</Subscript>

A new three-component catalytic system, PdCl₂/phen/M(CF₃SO₃)_n where M = La, Y, Yb, Zn, and Cu, was studied for the copolymerization of norbornene (NBE) with CO to prepare polyketone (PK). It was found that the CF₃SO₃H catalytic system gave a low catalytic activity for the copolymerization of norbornene with CO, but when M(CF₃SO₃)_n was introduced instead of CF₃SO₃H, the PdCl₂/phen/M(CF₃SO₃)_n catalytic system exhibited much higher activity. The effects of ligands, M(CF₃SO₃)_n, solvents, and temperatures on the copolymerization have been discussed in detail. The results showed that with 1,10-phenanthroline (phen) and Cu(CF₃SO₃)₂ used as cocatalysts, the corresponding reaction rate reached 82 000 g PK (mol Pd)⁻¹h⁻¹ when the reaction was carried out in methanol at 90°C and 3.0 MPa of CO, and the weight average molecular weight (M _w) of the resultant copolymer is 1090 g/mol. The copolymer was characterized with various techniques such as FT-IR, ¹HNMR, ¹³CNMR, TGA, and DSC. The infrared spectrum of the product includes two features at 1697 and 1732 cm⁻¹ for the NBE/CO copolymer in CH₃OH that are attributed to carbonyl groups in ketones (repeating unit) and esters (end group), respectively. Due to the tension of the ring of norbornene, the degree of copolymerization is not high. Published in Russian in Kinetika i Kataliz, 2007, Vol. 48, No. 1, pp. 51–58. This article was submitted by the authors in English.     

Gas-sensitivity properties of nanoscale Au-In<Subscript>2</Subscript>O<Subscript>3</Subscript> materials

A possibility was demonstrated of producing the chemical sensors based on Au-In₂O₃ obtained using a sol-gel technology. The sensors exhibit high sensitivity and selectivity toward CO. The differences in gas-sensitivity properties of In₂O₃ sensor with respect to CO and CH₄ at different ways of doping with Au(III) was examined. The effect of the gold nanoparticles size and the state of the indium oxide surface on the characteristics of Au-In₂O₃ and Au/In₂O₃ sensors at the detection of CO and CH₄ was examined.     

Calculated properties of neutral and charged Al<Subscript><Emphasis Type="Italic">n</Emphasis></Subscript>Co<Subscript><Emphasis Type="Italic">m</Emphasis></Subscript> clusters by density functional theory

Density functional calculations are performed to study the structures and electronic properties of Al _n Co _m clusters with n = 1–7 and m = 1–2. Frequency analysis is also performed after structural optimization to make sure that the calculated ground states are real minima. The corresponding total and binding energies, adiabatic electron affinities and ionization potentials are presented and discussed to aid the identification of our calculations. The BSSE correction is also considered in our calculation. Among Al _n Co _m , Al _n Co _m ⁻, and Al _n Co _m ⁼ clusters (n = 1–7 and m = 1–2), Al₄Co⁻, Al₆Co⁻, Al₂Co₂, and Al₆Co₂ are predicted to be more stable. Our results are consistent with the available experimental data.     

Synthesis and structure of the polymeric complex [Ag<Subscript>2</Subscript>(Ph<Subscript>3</Subscript>P)<Subscript>2</Subscript>B<Subscript>10</Subscript>H<Subscript>10</Subscript>]<Subscript><Emphasis Type="Italic">n</Emphasis></Subscript>

A method for the synthesis of the silver(I) complex with the closo-decaborate anion and triphenylphosphine [Ag₂(Ph₃P)₂B₁₀H₁₀] _n was developed and the structure of this complex was studied. The polymeric chain of the complex is formed with participation of Ag(I) atoms, which coordinate the B₁₀H₁₀²⁻ anions through the apical (B(1)–B(2), B(9)–B(10)) and equatorial (B(3)–B(6), B(5)–B(8)) edges, the metalligand bonding occurring through three-center two-electron bonds (MHB). The P atoms of two triphenylphosphine molecules are also incorporated in the inner coordination sphere of the metal: the CN of the silver atom is 4 + 1.     

New interpretation of progression bands observed in infrared spectra of nylon‐m/n

A series of progression bands observed in the infrared spectra of nylon‐m/n and their model compounds have been interpreted in a new manner on the basis of simply coupled oscillator models of zigzag alkyl chains. Nylon‐m/n possesses the methylene sequences of (CH₂)_m and (CH₂)_n?2, and so the effective models of m and n ? 2 coupled oscillators, respectively, had previously been assumed for the methylene rocking–twisting mode, for example. However, the spectral patterns of progression bands predicted by this previously proposed model have been found to be inconsistent with those observed for many kinds of nylon samples with various m and n values. It is rather reasonable to assume that the effective numbers of oscillators should be m ? 2 and n ? 4 for the methylene rocking, twisting, and wagging modes of the (CH₂)_m and (CH₂)_n?2 sequences, respectively. In other words, the infrared progression bands observed for methylene local modes of nylon‐m/n may be interpreted reasonably with the data of n‐alkane molecules with the chemical formulae CH₃(CH₂)_m?2CH₃ and CH₃(CH₂)_n?4CH₃. For the C? C stretching modes, the equivalent n‐alkanes are CH₃(CH₂)_m?1CH₃ and CH₃(CH₂)_n?3CH₃, respectively. In the simply coupled oscillator model, the vibrational mode of one methylene group is represented by an oscillator, for example. Our new concept is to isolate the terminal oscillator adjacent to the amide group from the other oscillators in the inner parts of the methylene zigzag sequence. This corresponds to a physical situation in which the methylene group adjacent to the amide group shows a different vibrational behavior of larger amplitude than those of the inner methylene sequence, as supported by broad‐line NMR data and molecular dynamics calculations reported in the literature. Another possibility is a difference in the electron structure of the methylene unit adjacent to the amide group from that of the inner methylene sequence, resulting in a difference in the force constant and giving a vibrational decoupling between these two types of methylene units. © 2003 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 41: 1294–1307, 2003     

Quantum-chemical study of C<Subscript>n</Subscript>F2<Subscript><Emphasis Type="Italic">n</Emphasis>+2</Subscript> conformers. Structure and IR spectra

Quantum-chemical calculations of the geometrical structure and vibrational spectra of C_nF_2n+2 oligomers (n = 5–8) in the chain and branched conformations are reported. The lengthening of the chain of C_nF_2n+2 does not substantially affect the geometrical parameters of the oligomers. In all cases under study, the most optimal structure of the molecule is a zigzag chain with bond lengths R(C-C) = 1.53 –1.54 and R(C-F) = 1.36 –1.34 ; the chain is rolled into a helix, which makes an angle of 17° with the plane. The IR spectra are sensitive to the structural deficiency of oligomers C_nF_2n+2 associated with the lateral trifluoromethyl groups formed in the chain; the spectra can be used for revealing defects of this type in the structure of polytetrafluoroethylene (PTFE). The possibility of defects associated with the lateral CF₃ groups in the structure of PTFE and its low-temperature modifications is explained based on the calculated total energies of C_nF2 _n+2.Original Russian Text Copyright © 2004 by L. N. Ignatieva, A. Yu. Beloliptsev, S. G. Kozlova, and V. M. BuznikTranslated from Zhurnal Strukturnoi Khimii, Vol. 45, No. 4, pp. 632–643, July–August, 2004.This revised version was published online in April 2005 with a corrected cover date.     

Solid-state chlorodecarboxylation of mono- and dicarboxylic acids with the Pb(OAc)<Subscript>4</Subscript>-MCl system

Solid state reactions of acids RCOOH (R = n-C₇H₁₅, BuC(Et)H, n-C₉H₁₉, PhCH₂, PhCH₂CH₂, H₂C=CH(CH₂)₈, or MeOOC(CH₂)₃) with Pb(OAc)₄ combined with KCl, NaCl, CdCl₂, or NH₄Cl in the absence of a solvent and without mechanical activation afford chlorohydrocarbons RCl. The corresponding reactions of acids HOOC(CH₂)_nCOOH (n = 3–6) give dichloroalkanes Cl(CH₂)_nCl and γ-butyrolactone (n = 3).__________Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 10, pp. 2105–2109, October, 2004.