Dynamics of optically induced anisotropy in an ensemble of asymmetric top molecules in the gas phase

A complex theoretical and experimental investigation of the evolution of optically induced anisotropy in an ensemble of free asymmetric tops under collisionless conditions is performed. The dynamics of the orientational correlation functions is studied and the results of femtosecond measurements of the relaxation of the anisotropy of perylene fluorescence in the gas phase are reported. The results obtained are interpreted in terms of the theory developed. It is shown that, in contrast to steady-state anisotropy, the time kinetics of optically induced anisotropy yields more complete and typical data on the dynamics of vector correlations in an ensemble of molecules.     

Synthesis and structures of oligothioarylenecyclophosphonites

A new representative of phospho(scIII)crown ethers was obtained based on 4,4-thiodiphenol and tetraethyldiamide of phenylphosphonous acid. Thiaphospho(III)crown ethers can be prepared by different methods depending on the ratio of the initial reactants and the reaction conditions. The structures of the compounds obtained were confirmed by spectroscopic data and X-ray structural analysis.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 9, pp. 2313–2315, September, 1996.     

Powder diffraction study of the crystal structure oftrans-Pd(NH3)2Cl2

Trans-Pd NH₃)₂Cl₂ was studied by powder diffractometry. The unit cell parameters are a = 6.5408(8), b = 6.8573(8), c = 6.3574(6) Å, a = 103.303(5), Β = 102.457(3), γ = 100.612(4); V = 262.63 ų, Z = 2, space group $P\bar 1$ . The atomic coordinates were established from Patterson syntheses and refined by the Rietveld method: R_p = 10.7%, R_wp = 10.2%, R_exp = 5.6%, R_B = 3.6%. The crystal structure is of molecular type. The planar trans-Pd(NH₃)₂Cl₂ molecules are packed parallel to each other into columns along the z axis, with every next molecule rotated through an angle of ～ π/2. The observed packing of columns reproduces the cis-isomer quite closely. The structure has a disordering at 0.1Pd positions at 1/2, 0, 0 and 1/2 1/2, 0. A possible explanation for the nature of additional positions is offered.     

Kinetics of platinum(II) and platinum(IV) sorption from hydrochloric acid solutions with a complexing ion exchanger containing thiourea functional groups and with a strongly basic anion exchanger

The kinetics of platinum(II) and platinum(IV) sorption from 2 M HCl with Purolite S920 complexing ion exchanger containing thiourea functional groups and Purolite A500 strongly basic anion exchanger was studied in relation to the resin granule size, stirring intensity, and temperature.     

Mass-spectrometric study of substituted tetrahydro-4-thiopyrones

The mass spectra of 16 methyl- and phenyl-substituted tetrahydro-4-thiopyrones that differ with respect to the position of the substituents in the ring and some of their deutero derivatives were studied. The principal pathways of dissociative ionization of these compounds are due to cleavage of the a bonds with respect to the heteroatom and the carbonyl group. Analytical features that make it possible to determine the position of the substituents in the tetrahydro-4-thiopyrone ring and distinguish the structural and spatial isomers in this series of compounds were found.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 5, pp. 619–626, May, 1981.     

Ion-exchange recovery of palladium(II) from multicomponent chloride solutions

Ion-exchange sorption of palladium(II) from both concentrated aqueous hydrochloric acid solution containing Fe(III), Sn(II), Zn(II), and Cu(II) and weakly acidic concentrated aqueous ammonium chloride solution containing Zn(II) and Cu(II) was studied. The Purolite S920, Purolite S924, and Purolite S984 macroporous resins with the thiourea, thiol, and polyethylenepolyamine functional groups, respectively, were used as sorbents. Strongly basic Purolite A500 anion exchanger was also tested. The desorption of palladium(II) with aqueous ammonia, hydrochloric acid, and acidified aqueous thiourea was examined.     

Formation of metastable crystals of [C4mim][NTf2] and [C6mim][NTf2]

Heat capacities of crystalline 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide [C₄mim][NTf₂] and 1-hexyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide [C₆mim][NTf₂] in the range 80 K-T_fus were measured in an adiabatic calorimeter. Anomalies in the heat-capacity curves for the both compounds occurred near 240 K. Positions of the anomalies depended on thermal history of the samples. More stable crystals had higher heat capacities in the range 220-260 K. Below 200 K heat capacities of all the crystals of the same compound were indistinguishable.