Crystal structure of methylbis(chloromethyl)phosphine oxide

In the crystal structure of (CH₂C1)₂P(O)CH₃ and the isomorphous crystal structures of (CH₂Br)₂P(O)CH₃ and (CH₂I)₂P(O)CH₃, the molecules of the methylbis(halomethyl)phosphine oxide have an identical trans, gauche conformation.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 7, pp. 1526–1528, July, 1991.     

Phosphorus-containing podands 7. Complexing properties of ortho-diphenylphosphinyl-substituted diphenyl ethers of oligoethylene glycols with respect to alkali-metal cations

Stability constants of complexes of alkali-metal cations with oligoethylene glycol diethers RO(CH₂CH₂O)_nR (n=1–5), where R=2-Ph₂P(O)C₆H₄ and 2-Ph₂(O)-4-t-BuC₆H₃P, have been determined conductometrically in a tetrahydrofuran-chloroform mixture (41 by volume). The dependence of complexing ability on a number of monopodand donor centers for Li⁺ and Na⁺ has multiple extrema. For K⁺, Rb⁺, and Cs⁺ the complexing abilities steadily increase with the length of the ligand polyether chain. Monopodands based on triethylene glycol and its pyrocatechol analog are highly effective (log K=6.7–7.0) with respect to Li⁺. The synthesis of ligands with a lipophilic tert-butyl substituent in the terminal group is described.For previous communication, see [1]. The number of the communication in [2] is 5, not 4 as printed in error.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 9, pp. 1992–2000, September, 1991.     

Displacement of metal atoms from salts by hydrogen and the role of this reaction in chain processes

The interaction of hydrogen atoms with a variety of alkali metal and alkaline-earth metal salts results not only in the recombination of these atoms but also in the displacement, into the gas phase, of free radicals (CaCl^·(A ¹ P _1/2, B ² S ⁺) and CaF^·(A ² P)) and metal atoms, including their excited species, which are detected spectroscopically. Transmission spectra indicate that the NaCl surface undergoes metallization when treated with a high-frequency discharge and a rarefied hydrogen flame. Combustion is affected by the gas-phase hydrogen atoms involved in the chain reaction and by the varying composition and properties of the surface. The concentration of Na atoms over the NaCl surface at 770 K is 10⁹?10¹¹ cm^?3 in a stream of H atoms at 1 Torr and in the 2H₂ + O₂ flame at 4 Torr. The concentration of sodium atoms in the ² P _3/2 and ² P _1/2 excited states is ～5 × 10⁶?5 × 10⁸ cm^?3. The role of the discovered reactions in combustion, pyrolysis, and plasma chemistry is discussed.     

Modulation effects in the electron spin echo of trans bis-(2,2,5,5-tetramethyl-3-imidazoline-3-oxide-1-oxyl-4-il) ethylene biradicals

Electron spin echo modulation effects have been investigated in trans bis(2,2,5,5-tetramethyl-3-imidazoline-3-oxide-1-oxyl-4-il) ethylene biradicals involving ¹⁴N or ¹⁵N nuclei in different positions. The modulation frequencies are shown to be the nitrogen nuclear transition frequencies in radical fragments at m_S = 0 of a triplet electronic spin. Quadrupole splitting parameters for these nitrogen nuclei have been determined.     

Level shift of μ mesoatoms and anomalous interaction of muons with nuclei

The effect of the possible anomalous interaction of a muon with nuclei, due to exchange of the muon and the nucleon, with vector V=⁰, , , J/, , and ⁰ mesons, on the level of the mesoatoms is considered. An estimate is carried out of the energy shift of the 2P-1S transition. A comparison of the estimates obtained for the 2P-1S transition energy shift in the mesoatom²⁰⁶Pb with the experimental data does not contradict the presence in the muon of an anomalous interaction with the nucleon, defined by the effective coupling constant /4 4·10^–4.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 6, pp. 75–80, June, 1978.     

Dynamic birefringence and conformation of molecules of aromatic polyamide-hydrazide in solutions

Flow birefringence (FB) in solutions has been investigated for a number of samples of polyamide-hydrazide (PPAH) in dimethylsulphoxide; intrinsic viscosities [η] of the same solutions have been measured. Characteristic values of FB, [η], and orientation angles [χ/g] of the solutions were determined. Molecular weights of the PPAH samples were calculated from values of [χ/g] and [η]. The use of characteristic values of [n] and [η] and the theory of optical anisotropy of persistent chains gives quantitative data on the equilibrium rigidity of PPAH molecules. It was shown that the length of the statistical segment of the PPAH chain is 800 Å. The possible reasons for the fact that the equilibrium flexibility of PPAH molecules is greater than that of poly-p-phenylene terephthalamide molecules have been discussed.     

Hydrodynamic and dynamo-optical properties and conformation of cyanoethyl cellulose molecules in solution

Translational diffusion, velocity sedimentation and viscosity in acetone as well as flow birefringence (FB) and viscosity in cyclohexanone have been investigated for cyanoethyl cellulose (CEC) with degree of substitution 2.6 in the range of M = (24.5?317) × 10³. The dependences of [ν], S_o and D_o on M were obtained. The value of the hydrodynamic constant is $\text{A}{}_0\text{= 3.27 × 10}{}^{\mathrm{?10}}\text{erg deg}{}^{\mathrm{?1}}\text{mol}{}^{\mathrm{<mtext>?</mtext><mtext>1</mtext><mtext>3</mtext>}}$. According to hydrodynamic data, the equilibrium rigidity of CEC molecules is characterized by the length of the Kuhn segment $\text{A = 240 ? 350}\text{A}\text{?}$ and the coefficient of hindrance to intramolecular motion σ = 4.5-5.4. The hydrodynamic diameter of the chain is 8–14 Å. According to the FB data, the value of A is 260 Å. This value is in agreement with hydrodynamic data. The high value of optical anisotropy of the monomer unit, a_| - a_⊥ = 17.8 × 10^?25 cm³, is in agreement with the structure and anisotropy of the substituting groups, and the investigation of orientation angles of FB leads to the conclusion that, apart from high equilibrium rigidity, CEC in solution is characterized by considerable kinetic chain flexibility. The data for CEC are compared with the characteristics of other cellulose esters and ethers.