Intermediacy of nitrene in the curtius-type rearrangement of phosphinic azides. Insights from Ab initio study of the H2P(O)N⇌HP(O)NH interconversion

Ab initio calculations on the model phosphinic nitrene H₂P(O)N⇌oxoiminophosphorane HP(O)NH interconversion in both lower-lying singlet and triplet states at the UMP4SDQ/6-31 ++ G^* level using the HF/3-21 G^*-optimized geometries are reported. The results support the proposition that the Curtius-type rearrangement of phosphinic azide (azidophosphine oxide) occurs via a non-nitrene mechanism in its singlet ground state. However, if the starting material could be sensitized photochemically into its triplet excited state, then the nitrene could be formed and the Curtius-type rearrangement would not be observed.     

An investigation of the polythermal diagram of the H2ONa2HPO4Na2SO4 system

The polythermal diagram of the ternary system H₂ONa₂HPO₄Na₂SO₄ has been established, setting up nine isotherms obtained between 0 and 25°C by conductimetric analysis. The solubility domains of the various solid phases have been determined. One eutectic, three stable and one metastable transitional transformations have been observed. Temperature and composition of the eutectic point have been obtained by thermal analysis at constant flow.     

Phase equilibrium diagram of the system MnCrO

A hypothetical oxygen pressure-composition phase diagram and a projection of the oxygen pressure-temperature-composition diagram on the composition triangle were constructed from phase equilibria in the system MnCrO on the basis of the data available in literature. The temperature-composition phase equilibrium diagram of this same system in air was specified. Isomorphism of solid solutions with spinel and hausmannite structure and their intertransformation was studied. Two chemical compounds, MnCr₂O₄ and Cr₄Mn₂₈O₄₈, are supposed to exist in the system.     

Fluorination behaviors of the complexes of RbFUF4 and CsFUF4 systems

The reaction behaviors between some complex fluorides of MFUF₄ system (M = Rb or Cs) and fluorine were investigated. In all the cases, uranium was oxidized to hexa-valent state at the temperatures between 300 and 500°C and M₂UF₈ type complex was formed, except for the cases of 3MF·UF₄ type complexes. In the fluorinations of 3MF·UF₄, products with the composition of M₃UF₉ were formed. A change in the stability of RbFUF₆ systems with RbF/UF₆ ratio was also investigated.     

Phase equilibria of the Ag2OTeO2V2O5 system

The phase diagram Ag₂OV₂O₅TeO₃ is studied in the region rich in TeO₂ with the aid of DTA and X-ray analysis. It is found that the sections TeO₂Ag₂O.V₂O₅.2TeO₂ and Ag₂O.TeO₂Ag₂O.V₂O₅.2TeO₂ are simple ones. A new compound with a composition of Ag₂O.3V₂O₅.6TeO₂ has been found in the section 2TeO₂.V₂O₅Ag₂O.V₂O₅.2TeO₂ which melts incongruently. A part of the liquidus diagram of the system in which the two ternary compounds participate is plotted.     

Synthesis of bi- and tervalent ligands of galectins,derivatives of β-lactosylamine,with the amino group in the terminal position of the spacer

A method for the synthesis of glycoclusters by N-alkylation of N-glycyl-β-lactosylamine with N-chloroacetyl derivatives of β-lactosylamine and N,N’-iminodiacetyldilactosylamine has been developed. The glycoclusters obtained with two and three lactosylamine residues with the amino group in the spacer were found to be suitable for further conjugation with carboxy-containing physiologically active compounds. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 3, pp. 647–651, March, 2008.     

New oxyborates in the MgMnBO system

Two new oxyborate compounds were synthesized during a study of the phase relationships between the pinakiolite-ludwigite series of compounds. The structural topologies of these previously unreported materials have been determined experimentally by comparing calculated with observed electron microscope images. Both of these structures are very similar to each other, and also closely related to pinakiolite which consists of flat walls of edge-sharing octahedra connected to zigzag chains of octahedra by triangular BO₃ groups. The two new structures contain similar infinite walls which are separated by slabs of octahedra that are wider than the zigzag chains found in pinakiolite. A new series of structurally related oxyborate compounds can be envisaged and are described.     

Nα-Acyl derivatives of arginine,bearing the di(2-chloroethyl)-amino group

Conclusions New derivatives of arginine containing the di(2-chloroethyl)amino group were produced.Translated from Izvestiya Akademii Nauk SSSR, Seria Khimicheskaya, No. 10, pp. 1899–1901, October, 1964     

The frequency of the HOH bending fundamental in solids and liquids

A survey has been made of HOH bending frequencies in water-containing solids and liquids, using data from the literature and from the author's laboratory. After the effects of hydrogen bonding and dynamic coupling have been allowed for, HOH bending frequencies are found to be lowered by cation—water interactions. This frequency lowering increases statistically with increasing cation charge and with decreasing cation size.     

Charakterisierung und photochemie von (dihalogenmethylen)sulfoxiden,XYCSO

Dihalogenomethylene sulfoxides (dihalogenosulfines) 2a–c were generated by flash vacuum pyrolysis of 2,2,4,4-tetrahalogeno-1,3-dithietane 1,3-dioxides 1a–c and trapping the pyrolysis products in argon at 10 K. At room temperature unstable difluorosulfine (2a) and chlorofluorosulfine (2b) were identified by i.r. spectroscopy, and the photochemistry of the sulfines was investigated. Chlorofluorosulfine (2b) exists in two geometrical isomers. Photolysis of 2a leads to fragmentation to give CF₂ and SO, photolysis of the chlorine containing sulfines 2b and 2c to rearrangement to give the sulfenyl chlorides 6 and 8. This is explained by different migratory tendencies of fluorine and chlorine and the stability of the CF bond.     

Phase equilibria in the ternary system: MgONa2OP2O5: Partial system: Mg3(PO4)2Mg4Na(PO4)3Na4P2O7Mg2P2O7

The partial system Mg₃(PO₄)₂Mg₄Na(PO₄)₃Na₄P₂O₇Mg₂P₂O₇ in the ternary system MgONa₂OP₂O₅ was investigated using thermal and X-ray diffraction analyses and microscopy, and its phase diagram has been determined. In this range of composition, two binary phosphates occur: Mg₄Na(PO₄)₃ and Mg₆Na₈(P₂O₇)₅. The former melts incongruently (at 1155°C) and the latter does congruently (at 808°C). In the partial system of interest, the two sections Mg₄Na(PO₄)₃Mg₂P₂O₇ and Mg₄Na(PO₄)₃Mg₆Na₈(P₂O₇)₅ are studied, and their phase diagrams are established. The partial system is divided into three partial ternary systems in which two ternary eutectics and one ternary peritectic occur.     

High-Tc superconductivity in the ErBaCuO and related systems

ErBa₂Cu₃O₇ and Er_0.5Y_0.5Ba₂Cu₃O₇ are both high-T_c superconductors attaining zero resistance above 80 K. Preliminary studies indicate that Yb_1−xY_xBa₂Cu₃O₇ also exhibits zero resistance above 77 K.     

Calculations for the vibration frequencies of the OH⋯O bond in KH2PO4 by a semiempirical method

The frequencies of the stretching vibration and the bending vibration of the OH⋯O bond in potassium dihydrogen phosphate have been calculated by means of two semiempirical formulae with three parameters. The calculated results can give satisfactory explanation for the experimental spectra of the potassium dihydrogen phosphate crystal. The parameters used in the calculations may be related to the chemical bonding and the charge distribution about the two oxygen atoms of the OH⋯O bond system.     

Influence of the ester group during the enantioselective methylation of α-aldehyde esters via their chiral oxazolidine derivatives

Depending on the nature of the ester group, fair asymmetric induction (ee's up to 82%) can be attained in the title reaction.     

Comparison of the magnetic properties of MmFeband NdFeB compounds

NdFeB and corresponding MmFeB compounds were studied, the high field magnetization at 4.2 K, the a.c. susceptibility (4.2 < T < 300 K) and the anisotropy field were measured using the singular point detection technique (77 < T < 570 K). At room temperature the anisotropy field of the MmFeB is about 3T, whereas that of NdFeB compounds is about 7T. The MmFeB compounds showed effects due to the cerium (lowering the Curie temperature) as well as due to the neodymium (spin reorientation at low temperatures).     

Infrared spectra of aluminogermanate- and aluminate-sodalites and a re-examination of the relationship between TO bond length,TOT angle and the position of the main i.r. absorption band for compounds with framework structures

Cell parameters and i.r. data are presented for 6 aluminogermanate-sodalites, 11 aluminate-sodalites and for Na₈(Ga₆Ge₆O₂₄)Br₂ and Na₈(Ga₈Si₆O₂₄)Br₂. Apart from the borate-sodalites the framework absorption bands of the sodalite family can be grouped into three sets: ν_as TOT between 800 and 1000 cm⁻¹, ν_s TOT between 500 and 800 cm⁻¹ and δ OTO between 300 and 500 cm⁻¹ (T =tetrahedral framework cation). The aluminogermanate-sodalites have one ν_as TOT mode and two v_s TOT and δ OTO modes. Cubic aluminate-sodalites with ∼ 9 Å cells are similar but with only one δ OTO mode; aluminate-sodalites without cubic ∼9 Å cells showed broadening of the v_as TOT mode, which has several maxima and additional v_s TOT bands. Compounds with framework structures having AlO, (Al, Ge)O, (Al, Si)O, (Ga, Ge)O, GeO and SiO framework bonds, when grouped into those with TOT angles close to either 125° or 145°, show good correlations between the wave numbers of their main absorption bands and their mean TO distances.     

Thermodynamics of the URuC system

Thermodynamic measurements by the electromotive force method were made on the binary intermetallic phases URu₃ and U₃Ru₅ and on the ternary carbides URu₃C_0.7 and U₂RuC₂ of the URu and the URuC systems between 950 and 1200 K using galvanic cells with CaF₂ single crystal electrolytes: U, UF₃¦CaF₂¦UF₃, URu₃, Ru; U, UF₃¦CaF₂¦UF₃, U₃Ru₅, URu₃; Ru, URu₃, UF₃¦CaF₂¦UF₃, URu₃C_0.7, Ru, C; U, UF₃¦CaF₂¦UF₃, URu₃C_0.7, U₂RuC₂, C. The Gibbs energies of formation of URu₃, U₃Ru₅, URu₃C_0.7 and U₂RuC₂ were evaluated from the measured electromotive force which give ^fΔG^o〈URu₃〉 = −199 100 + 35.9 T J mol^−1fΔG^o〈U₃Ru₅〉 = −398 600 + 43.6 T J mol^−1fΔG^o〈URu₃C_0.7〉 = −192 600 + 2.5 T J mol^−1fΔG^o〈U₂RuC₂〉 = −380 200 + 52.5 T J mol⁻¹ The implications of these thermodynamic data for the behaviour of the fission product ruthenium in irradiated carbide fuels are discussed.