Low-frequency intramolecular and lattice vibrations of n-C36H74 as studied by Raman scattering

The Raman spectrum of n-C₃₆H₇₄ has been measured in the region between 0 and 150 cm^?1. Eleven newly observed bands have been assigned to the intramolecular skeletal vibrations and rotatory lattice vibrations on the basis of the dispersion curves calculated previously.     

Vibrational and calorimetric study of phase transitions in n-C6F14 and n-C8F18 crystals

Heat capacities of n-perfluorohexane and n-perfluorooctane were measured from 4.2 K to room temperature. One solid—solid transition is found for n-C₆H₁₄,two for n-C₈F₁₈. Spectra show that the molecules have the same conformations in the two forms of n-C₆F₁₄. Several isomers are present in the high-temperature forms of n-C₈F₁₈;thus transitions in this compound have order—disorder character.     

Raman study of the structure of cobaltacarborane complexes containing dicarbollide and dicarbacanastide ligands

A series of cobaltacarborane complexes including Cs[(1,2-C₂B₉H₁₁)₂Co], Cs[(8,9,12-Br₃-C₂B₉H₈)₂Co], Cs[(8-I-C₂B₉H₁₀)₂Co], and polynuclear chain cobaltacarborane complexes of the general formula Cs_n[(1,2-C₂B₉H₁₁)₂Co_n(1,2-C₂B₈H₁₀)_n-1], where n=2,3,4,5,6,7, were studied by Raman spectroscopy. In the Raman spectra of these complexes, the frequencies and intensities of the bands of the ligand-metal-ligand totally symmetric stretching vibrations are characteristic; therefore, these data may be used as analytical characteristics. Institute of Inorganic Chemistry, Siberian Branch, Russian Academy of Sciences. Translated fromZhurnal Strukturnoi Khimii, Vol. 37, No. 4, pp. 716–720, July–August, 1996. Translated by L. Smolina     

Homo- and copolymerization of styrene and 1-alkene using Ph2Zn-Et(Ind)2ZrCl2-MAO initiator systems

Homopolymerization of α-olefins (1-C_nH_2n, n = 6, 8, 10, 12, 16 and 18) and their copolymerization with styrene were carried out in toluene at 60 °C using diphenylzinc-ethenylbisindenylzirconium dichloride-methylaluminoxane as initiator system. Atactic polystyrene and almost isotactic poly(α-olefin)s were obtained. Copolymerization of S/α-olefin with this initiator system gave isotactic olefin-enriched copolymers. According to DSC analysis, the homopolymers P(1-C₁₂H₂₄), P(1-C₁₆H₃₂), and P(1-C₁₈H₃₆) as well their styrene copolymers are crystalline.     

Vibrational analysis of 1-iodopropane-D7 and 1-iodobutane-D9: A force field for primary iodides

Infrared and Raman spectra were obtained for n-C₃D₇I and n-C₄D₉I that showed the existence of rotational isomers. The conformer with a co-planar chain of carbons and iodine is the one stable in the crystals of both compounds, analogous to the protonated species. Vibrational assignments were made with the aid of normal coordinate calculations. Force constants were determined by simultaneously fitting the calculated to the observed frequencies for 155 values of the eight molecules, trans and gauche n-C₃H₇I, trans and gauche n-C ₃D₇I, TT and TG n-C₄H₉I, and TT and TG n-C₄D₉I. The average error for the 155 frequencies is 6.3 cm^?1.     

Raman spectrum of n-C23H48 and n-C44H90 at high pressures: Fermi resonance between the CH2 deformation and bending modes

Resonance interaction in the deformation (1400 to 1500 cm^?1) region of the Raman spectrum of n-C₂₃ H₄₈ and n-C₄₄H₉₀ at high pressures are reported. Implications of these results concerning the interpretation of the corresponding bands of the Raman spectrum of crystalline polyethylene are discussed.     

The hapticity of cyclooctatetraene in its first row mononuclear transition metal carbonyl complexes: Several examples of octahapto coordination

The two cyclooctatetraene metal carbonyls that have been synthesized are the tetrahapto derivative (η⁴-C₈H₈)Fe(CO)₃ and the hexahapto derivative (η⁶-C₈H₈)Cr(CO)₃ using the reactions of cyclooctatetraene with Fe(CO)₅ and with fac-(CH₃CN)₃Cr(CO)₃, respectively. Related C₈H₈M(CO)_n (M = Ti, V, Cr, Mn, Fe, Co, Ni; n = 4, 3, 2, 1) species have now been investigated by density functional theory in order to explore the scope of cyclooctatetraene metal carbonyl chemistry. In this connection, the existence of octahapto (η⁸-C₈H₈)M(CO)_n species is predicted as long as the central metal M does not exceed the 18-electron configuration by receiving eight electrons from the η⁸-C₈H₈ ring. Thus the lowest energy structures (η⁸-C₈H₈)Ti(CO)_n (n = 3, 2, 1), (η⁸-C₈H₈)M(CO)_n (M = V, Cr; n = 2, 1), and (η⁸-C₈H₈)Mn(CO) all have octahapto η⁸-C₈H₈ rings. An exception is (η⁶-C₈H₈)Fe(CO), with a hexahapto η⁶-C₈H₈ ring and thus only a 16-electron configuration for the iron atom. Hexahapto (η⁶-C₈H₈)M(CO)_n structures are predicted for the known (η⁶-C₈H₈)Cr(CO)₃ as well as the unknown (η⁶-C₈H₈)Ti(CO)₄, (η⁶-C₈H₈)V(CO)₃, (η⁶-C₈H₈)Mn(CO)₂, and (η⁶-C₈H₈)Fe(CO)₂ with 18, 18, 17, 17, and 18 electron configurations, respectively, for the central metal atoms. There are two types of tetrahapto C₈H₈M(CO)_n complexes. In the 1,2,3,4-tetrahapto (η⁴-C₈H₈)M(CO)_n complexes two adjacent CC double bonds, forming a 1,3-diene unit similar to butadiene, are bonded to the metal atom. In the 1,2,5,6-tetrahapto (η^2,2-C₈H₈)M(CO)₃ derivatives two non-adjacent CC double bonds of the C₈H₈ ring are bonded to the metal atom. The known (η⁴-C₈H₈)Fe(CO)₃ is a 1,2,3,4-tetrahapto complex. The unknown isomeric 1,2,5,6-tetrahapto complex (η^2,2-C₈H₈)Fe(CO)₃ is predicted to lie ∼15 kcal/mol above (η⁴-C₈H₈)Fe(CO)₃. The related 1,2,5,6-tetrahapto complexes (η^2,2-C₈H₈)Cr(CO)₄, (η^2,2-C₈H₈)Mn(CO)₄, [(η^2,2-C₈H₈)Mn(CO)₃]⁻, (η^2,2-C₈H₈)Co(CO)₂, and (η^2,2-C₈H₈)Ni(CO)₂ are all predicted to be low-energy structures.     

Observation of multiple phase transitions in some even n-alkanes using a high resolution and super-sensitive DSC

The phase transitions of even n-alkanes, n-C₃₄H₇₀, n-C₃₆H₇₄, n-C₄₀H₈₂ and n-C₄₂H₈₆ with high purity have been measured using a high resolution and super-sensitive DSC. A new transition in the low temperature phase was observed in all the samples in the heating run. The surface freezing phenomenon was observed by thermal measurement for the first time in all the samples both in the heating and in the cooling run. The difference of the thermal behaviors between the heating and cooling run was also observed in all the samples.     

A thermogravimetric study of lithium tetraalkoxyborates

Properties of lithium tetraalkoxyborates Li[t-C₄H₉OB(OR)₃] (R = n-C₄H₉ to n-C₈H₁₇, n-C₁₂H₂₅) were studied by differential thermogravimetry. The kinetic parameters and heat effects of thermal decomposition of lithium tetraalkoxyborates in air and inert gas atmosphere as functions of the carbon chain length were determined.     

Preparation and characterization of dichlorobis(N-alkyl-substituted salicylideneaminato)manganese(IV) complexes

A series of dichlorobis(N-alkyl-substituted salicylideneaminato)manganese(IV) complexes, Mn(N-R-Xsal)₂Cl₂, was prepared by the reaction of Mn(NRXsal)₂Cl complexes with hydrogen chloride, where R can be n-C₈H₁₇ (Oct), n-C₁₂H₂₅ (Dod), n-C₁₈H₃₇ (Octd), and CH₂C₆H₅ (Bz) and X can be 5-bromo, 5-nitro, and 5,6-benzo groups. These complexes were characterized by the magnetic susceptibilities, IR and electronic spectra, and cyclic voltammograms.     

Synergistic complexes of uranyl ion with 1-phenyl-3-methyl-4-acetyl-pyrazolone-5 and some oxo-donors

Complexes of uranyl ion with 1-phenyl-3-methyl-4-acetyl-pyrazolone-5(PMAP) and various oxo-donors such as aliphatic sulphoxides [R₂SO, where R = i-C₅H₁₁(DISO), n-C₆H₁₃(DHSO), n-C₇H₁₅(DSSO), n-C₈H₁₇(DOSO), n-C₉H₁₉(DNSO), n-C_1OH₂₁(DDSO), n-C₁₁H₂₃(DUDSO) and n-C₄H₉(DBUSO)] tributylphosphate (TBP) and tri-n-octyl phosphine oxide (TOPO) have been synthesised and characterized. Analytical data establish that they have the stoichiometry UO₂(PMAP)₂X where X is the oxo-donor. The IR spectra of the sulphoxide complexes in the SO stretching region indicate that the ligands R₂SO are O-bonded. The methyl protons of the pyrazole ring and acetyl group in the PMAP ligand are equivalent giving rise to a single sharp peak in the PMR spectra, whereas in the synergistic complexes with the oxo-donors, two deshielded peaks of equal intensity are observed which indicate the non-equivalence of the methyl groups. The peak which is more deshielded has been ascribed to the methyl of the acetyl group. The higher deshielding of these methyl protons arises due to the transfer of electron density to the metal atom on complexation.     

Prediction of activity coefficients and Henry's constants at infinite dilution for mixtures of n-alkanes

Trejo Rodríguez, A. and Patterson, D., 1984. Prediction of activity coefficients and Henry's constants at infinite dilution for mixtures of n-alkanes. Fluid Phase Equilibria, 17: 265–279.The corresponding-states principle (CSP) for chain molecules has been used to predict activity coefficients γ_i^∞ at infinite dilution and Henry's constants H_i,j for mixtures of n-alkanes. The mixtures for which predictions of γ_i^∞ are made include n-C₄ through n-C₁₀ as the solute in several pure higher n-alkanes, at several temperatures from 30 to 90°C. Predictions of H_i,j are made for mixtures where the solute is C₂ through n-C₈ and the solvent any n-alkane from n-C₄ through n-C₂₂, also at several temperatures, from –15 to 177°C. The predicted values are compared with experimental data from the literature, and in all cases the agreement is remarkably good. The temperature dependence of H_i,j for some mixtures is used to derive heats of solution ΔH_s, and comparison is again carried out with available experimental values.     

Onium Sulfates and Hydrogen Sulfates: Products of Reactions of Sulfur(IV) Oxide with Aqueous Solutions of Alkylamines and Aniline

The reaction products formed in the SO₂–L–H₂O–O₂ systems (L is n-propylamine, n-butylamine, tert-butylamine, n-heptylamine, n-octylamine, aniline) were isolated and identified as “onium” salts [n-C₃H₇NH₃]₂SO₄, [n-C₄H₉NH₃]₂SO₄, [t-C₄H₉NH₃]₂SO₄, [n-C₇H₁₅NH₃]₃SO₄(HSO₄), [n-C₈H₁₇NH₃]₃SO₄(HSO₄), and [C₆H₅NH₃]₂SO₄. The products were characterized by elemental analysis, IR and Raman spectroscopy, mass spectrometry, and thermogravimetry.     

Thermodynamic study of the n-octane-1-pentanol-sodium dodecyl sulfate solutions in water

The thermodynamic properties, PVTx (T_S, P_S, ρ_S), (∂P/∂T)_VX, and C_VVTx, of three microemulsions (water + n-octane + sodium dodecylsulfate + 1-pentanol) with composition of solution-1: 0.0777 (H₂O):0.6997 (n-C₈H₁₈):0.0777 (SDS):0.1449 (1-C₅H₁₁OH) mass fraction; solution-2: 0.6220 (H₂O):0.1555 (n-C₈H₁₈):0.0777 (SDS):0.1448 (1-C₅H₁₁OH) mass fraction; and solution-3: 0.2720 (H₂O):0.5054 (n-C₈H₁₈):0.0777 (SDS):0.1449 (1-C₅H₁₁OH) mass fraction were measured. Sodium dodecylsulfate (SDS) was used as an ionic surfactant, 1-pentanol used as stabilizer (cosurfactant), and n-octane as oil component in aqueous solution. A high-temperature, high-pressure, adiabatic, and nearly constant-volume calorimeter supplemented by quasi-static thermogram technique was used for the measurements. Measurements were made at eight densities (isochores) between 475.87 and 919.03 kg m⁻³. The range of temperature was from 275 to 536 K and pressure range was up to 138 bar. Uncertainty of the pressure, density, derivative (∂P/∂T)_VX, and heat capacity measurements are estimated to be 0.25%, 0.02%, 0.12-1.5%, and 2.5%, respectively. Temperatures at liquid-gas phase transition curve, T_S(ρ), for each measured densities (isochores) were determined using a quasi-static thermogram technique. The uncertainty of the phase transition temperature measurements is about ±0.02 K. The effect of temperature, density, and concentration on the heat capacity of the microemulsions is discussed. Along the isochore of 438.40 kg m⁻³ at temperatures above 525.44 K for the first solution the precipitation of the solid phase (SDS) was found.     

Phase behavior of n-octadecane in the form of water dispersion by the optical method

An aqueous dispersion of n-octadecane (n-C₁₈H₃₈) with a dispersed phase particle size of ～100 nm was prepared by ultrasonic dispersion method without the addition of surfactants. The temperatures of melting, crystallization and transitions to rotator phases were determined by the optical method (light scattering). The effect of surface crystallization was observed experimentally.     

Isobutene-isoprene copolymerization initiated by [Cp∗MMe2][(n-C18H37E)B(C6F5)3] (M = Ti, Hf; E = O, S) and related compounds

The highly electrophilic borane B(C₆F₅)₃ reacts with e.g., n-octadecanol (n-C₁₈H₃₇OH) and n-octadecanethiol (n-C₁₈H₃₇SH) to form equilibrium mixtures of the reactants and their 1:1 adducts (n-C₁₈H₃₇EH)B(C₆F₅)₃ (E = O, S). The latter are acidic, and react with Cp∗MMe₃ (M = Ti, Hf) in polar and non-polar solvents to give methane and the unstable complexes [Cp∗MMe₂][(n-C₁₈H₃₇E)B(C₆F₅)₃]. The latter are very good initiators for the copolymerization of isobutene with isoprene at relatively high temperatures, giving high conversions to high molecular weight isobutene-isoprene copolymers. The weight average molecular weights are unusually high for the temperatures used, consistent with current theories of the role of weakly coordinating anions. The effects of changing the substituents on the alcohols are also investigated.     

Acetyl-containing phosphine oxides as extractants for actinides and lanthanides

Extraction capability and selectivity of acetyl-containing phosphine oxides R₂P(O)CMe₂CH₂C(O)Me (R = Pr, Bu, n-C₅H₁₁, n-C₆H₁₃, n-C₈H₁₇, Ph) toward actinides (U^VI, Th^IV) and trivalent lanthanides (La^III, Nd^III, Ho^III, Yb^III) were studied. The new ligands were shown to be more efficient and selective in the extraction of uranium, thorium, and heavy lanthanides from nitric acid solutions into chloroform as compared to the known extractants such as carbamoylphosphine oxide Ph₂P(O)CH₂C(O)NBu₂, trioctylphosphine oxide (n-C₈H₁₇)₃P(O), and tributyl phosphate (n-BuO)₃P(O).     

Vibrational frequencies,infrared absorption intensities and energy differences between rotational isomers of propyl halides

Infrared absorption intensities of fundamental bands of propyl halides n-C₃ H₇ Cl, n-C₃H₇ Br and n-C₃H₇I were measured in the pure liquid state. In order to obtain L matrix data necessary for the intensity computation, normal frequencies of the rotational isomers were calculated, and LSFF force constants were determined by the least squares method so as to attain the best fit between the observed and calculated frequencies. By applying the absolute intensity method, energy differences between the rotational isomers were evaluated, which are in quite good agreement with values obtained by the temperature variation method.     

Facile synthesis of new polyolefinic ruthenium(0) complexes from ruthenium(II) precursors

The new ruthenium(II) complex [(C₈H₁₀)RuCl₂]_n (1) (C₈H₁₀ = 1,3,5-cyclooctatriene; n ⩾ 2) has been obtained from the reaction of RuCl₃·xH₂O with 1,3,5,7-cyclooctatetraene in refluxing ethanol. Reduction of [(C₈H₁₀)RuCl₂]_n and [(C₇H₈)RuCl₂]₂ (2) (C₇H₈ = 1,3,5-cyclooctatriene) by Na/Hg amalgam in the presence of isoprene (C₅H₈) gives the novel ruthenium(O) complexes [(η⁶-C₈H₁₀)Ru(η⁴-C₅H₈)] (3) and [(η⁶-C₇H₈)Ru(η⁴-C₅H₈)] (4). [(η⁶-C₇H₈Ru(η⁴-C₅H₈)] reacts with CO and HBF₄ to give [(η⁶-C₇H₈)Ru(η³-C₅H₉)(CO)][BF₄] (C₅H₉ = trans-1,2-dimethylallyl (5a); 1,1-dimethylallyl (5b)).     

Octahapto cyclooctatetraene rings and metal-metal multiple bonds in binuclear niobium carbonyl chemistry

Theoretical studies on (C₈H₈)₂Nb₂(CO)_n (n = 6, 5, 4, 3, 2, 1) predict structures mainly with octahapto and tetrahapto C₈H₈ rings. In all cases, the lowest energy singlet spin state structures lie below the corresponding lowest energy triplet spin state structures. Thus the lowest energy (C₈H₈)₂Nb₂(CO)₄ structure has two η⁸-C₈H₈ rings and an unbridged Nb-Nb single bond of length ∼3.15 Å. The lowest energy (C₈H₈)₂Nb₂(CO)₂ structure has two η⁸-C₈H₈ rings but a doubly bridged NbNb triple bond of length ∼2.64 Å. The lowest energy structure of (C₈H₈)₂Nb₂(CO)₃ also has a formal NbNb triple bond of similar length (2.66 Å) but with only one of the rings fully coordinated as an octahapto η⁸-C₈H₈ ligand. The other C₈H₈ ring in this tricarbonyl has “slipped” to form a hexahapto η⁶-C₈H₈ ligand. The lowest energy structure of the monocarbonyl (C₈H₈)₂Nb₂(CO) again has two octahapto η⁸-C₈H₈ rings and an extremely short NbNb distance of 2.45 Å, suggesting a formal quadruple bond. The lowest energy structures for the carbonyl-richer species (C₈H₈)₂Nb₂(CO)_n (n = 6, 5) have one η⁸-C₈H₈ and one η⁴-C₈H₈ ring (n = 5) and two η⁴-C₈H₈ rings (n = 6). The qualitatively assigned Nb-Nb bond orders are consistent with the Wiberg bond indices obtained from the Weinhold natural bond orbital analysis. Comparison of the (C₈H₈)₂Nb₂(CO)_n (n = 6, 5, 4, 3, 2, 1) derivatives with the isovalent (C₇H₇)₂Mo₂(CO)_n is made.