New polynuclear cobalt trimethylacetate complexes: synthesis and structure

Extraction of polymer (1), formed in the reaction of CoCl₂ with KOOCBu^t, with boiling hexane gives crystals of hexamer Co₆(μ₃-OH)₂(OOCBu¹)₁₀(HOOCBu¹)₄ (2). According to data of X-ray study, four Co¹¹ atoms in the hexanuclear molecule2 have an octahedral ligand environment and two Co¹¹ atoms have a tetrahedral one. Dissolution of polymer1 in EtOH results in its splitting into Co₄(μ₃-OH)₂(OOCBu¹)₆(HOEt)₆ tetramers (3). In molecule3, two asymmetric dimeric (η²-OOCBu^t)(EtOH)Co(μ-OOCBu^t)Co(HOEt)₂ fragments are bound by two tridentate bridging OH groups. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 9, pp. 1773–1778, September, 1999.     

Density and Viscosity of a Ternary $$ x_{1} $$ 1-He xene(1) + $$ x_{2} $$ x2 1-Octene(2) + (1 − − x2) 1-Decene(3) Mi xture at High Temperatures and High Pressures

The density and viscosity of a ternary 1-hexene(1) + 1-octene(2) +1-decene(3) mixture (\( w_{1} = w_{2} = w_{3} = 0.333 \) weight fractions or \( x_{1} = 0.4257 \),\( x_{2} = 0.3190 \), \( x_{3} = 0.2553 \) mole fractions of 1-hexene, 1-octene, and 1-decene, respectively) have been simultaneously measured over the temperature range from (298 to 471) K and at pressures up to 196 MPa using a combined method of hydrostatic weighing and falling-body techniques, respectively. The combined expanded uncertainties of the density, pressure, temperature, concentration, and viscosity measurements at the 95% confidence level with a coverage factor of k = 2 are estimated to be (0.15 to 0.30)%, 0.05%, 0.02 K, 0.005 mol%, and (1.5 to 2.0)%, respectively. The measured densities and viscosities were used to calculate the excess molar volumes and viscosity differences. The excess molar properties (\( G_{\text{m}}^{\text{E}} , \, H_{\text{m}}^{\text{E}} , \, S_{\text{m}}^{\text{E}} \) and \( C_{\text{pm}}^{\text{E}} \)) and their pressure derivatives as a function of temperature and pressure have been calculated using the derived excess molar volumes. The measured viscosities were used to develop a theoretically based viscosity correlation model (Arrhenius–Andrade type equation) for the mixture.     

Superacid mediated hydroxyalkylation reaction of 1,2,3‐indanetrione: a theoretical study

Energies of mono‐ and multiprotonation for 1,2,3‐indanetrione and ninhydrin in triflic acid (TFSA) media were estimated at PBE0/aug‐cc‐pvtz//6‐31+G** level of theory. The reactivity of formed intermediates in the reaction of aromatic electrophilic substitution has been studied at the same level of theory. It appears that the basicity of carbonyl groups in 1,2,3‐indanetrione is extremely low due to mutual influences of carbonyl groups. Carbonyl 2 is the least basic but the most reactive in accordance with experiment. Calculations demonstrated that monoprotonated intermediates are the principal reactive species in the reaction of hydroxyalkylation of 1,2,3‐indanetrione in TFSA. A new isomerization mechanism of 2,2‐diaryl‐1,3‐indanediones to 3‐(diarylmethylene)isobenzofuranones in TFSA media has been proposed. Copyright © 2010 John Wiley & Sons, Ltd.     

On numerical modeling of the dynamics of turbulent wake behind a towed body in linearly stratified medium

Two numerical models of the dynamics of a turbulent wake behind a towed body in a linearly stratified medium are compared, namely, the model based on direct numerical integration of Navier-Stokes equations in the Oberbeck-Boussinesq approximation and the mathematical model with applying a semiempirical turbulence model of the second order. The calculation results of the two models are similar to the known experimental data and are in good agreement.     

Synthesis and properties of macroheterocyclic compounds containing 1-imino-2-phenyl-1H-inden-3-amine fragments

Reaction of 1-imino-2-phenyl-1H-inden-3-amine with 3,3′-dichloro-, 2,2′-disulfo-, and 2,2′-dinitrobiphenyl-4,4′-diamines gave 2 : 1 and 1 : 2 linear condensation products and symmetrical macroheterocycles. The products were characterized by the IR, UV, and 1H NMR data.     

Possible Skeletal Transformations of Cyclooctatetraene in Its Thermal Isomerization

Russian Journal of Organic Chemistry - All possible transition state structures that could mediate thermally induced skeletal transformations of cyclooctatetraene in an oxygen-free atmosphere have...     

Formation and pharmacological activity of silicon—chitosan-containing glycerohydrogels obtained by biomimetic mineralization

The biomimetic sol—gel synthesis of silicon—chitosan-containing glycerohydrogels was carried out using silicon tetraglycerolate as a precursor. It was found that chitosan accelerates gel formation in weakly acidic media. In more acidic media, the kinetics of the process changes according to the curve with a maximum, which can be attributed to different mechanisms of silanol condensation before and after the isoelectric point. The investigated silicon—chitosan-containing glycerohydrogels exhibit antibacterial, anti-inflammatory, and wound healing activity. The synthesized hybrid glycerohydrogels are promising materials for biomedical applications.     

Destruction of polymeric cobalt(ii) trimethylacetate. Synthesis and structures of new complexes Co9(μ3-OH)6(μ-OOCCMe3)12(OCMe2)4 and Co6(μ4-O)2(μ-OOCCMe3)10(η-HOOCCMe3)4

Russian Chemical Bulletin -     

Free Vibrations of Transversely Isotropic Hollow Cylinders

An asymptotic process for evaluating the frequencies of free axisymmetric vibrations of transversely isotropic hollow cylinders is proposed. This process is developed in detail for a cylinder with hinge-supported ends and free lateral surfaces. The approaches which make it possible to construct algorithms for identifying their natural frequencies within the given interval are tested on model problems. The results from the Kirchhoff-Love and Ambartsumyan theories are compared with those from the 3D elasticity theory. In the first term of an asymptotic expansion, two frequencies coinciding with those obtained using the applied shell theory are found and a countable set of frequencies absent in this theory is determined.