Jahn–Teller effect and the formation of anticorrosive protective layers of nitrilo-tris-methylene-phosphonates on surfaces of steel

Nitrilo-tris-methylene-phosphonato-three-aqua-complexes of chromium(II) and iron(II), the main components of protective layers for inhibiting steel corrosion with nitrilo-tris-methylene-phosphonates, are isolated and studied. Their ability to form protective layers is explained by their insolubility and resistance to water and air. These properties of Cr and Fe complexes are explained by Jahn–Teller distortion of the coordination environment of Cr and Fe atoms.     

A general method for alkylating 2(5H)-furanones; reduction of products to 3-, 2,3-, and 3,4-substituted furans

The cycloaddition of diazoalkanes, diazoesters and diazoketones to 2(5H)-furanones followed by thermal decomposition of the respective adducts is shown to provide a general method for the preparation of a variety of alkylated 2(5H)-furanones. Reduction of the latter compounds with diisobutylaluminum hydride affords the corresponding substituted furans in good yield.     

New Salt Spiropyran of Indoline Series with Fluorine Substituent

Synthesis, study of structure and photochromic properties of new salt spiropyran of indoline series containing a fluorine substituent in the 6′-position of the 2H-chromene moiety have been described in the work. The structure of the compound has been confirmed by ¹H NMR spectroscopy and X-ray diffraction analysis. Comparison of the structure of the compound with the previously studied analogue containing a methyl group instead of a fluorine atom in the 6′-position of the [2H]-chromene moiety has been made. This compound has been found to be photochromic, long-wavelength absorption maximum of its open form shows a bathochromic shift, and lifetime is increased three times as compared with the methyl analogue.     

Quantum-chemical modeling of possible reactions of Roussin’s red esters with aryl ligands in DMSO solution

Possible reactions of Roussin’s red esters [Fe₂(μ-SC₆H₄R)₂(NO)₄], where R = H, o-NH₂, m-NO₂, m-OH, or m-NH₂, in DMSO solution were investigated by quantum chemical modeling. It was shown that in these systems, numerous reactions can occur, including NO donation, ligand substitution, and decomposition into mononuclear iron nitrosyl complexes. The resulting compounds are also NO donors.     

Thermal and Thermo-Oxidative Destruction of Poly(Ethylene Terephthalate) Modified with Formulation Based on Polyfluorinated Alcohol

Stabilizing effect of 1,1,9-trihydroperfl uorononanole-1 immobilized on a montmorillonite support on the stability of poly(ethylene terephthalate) at elevated temperatures was studied. Gas chromatography, IR Fourier spectroscopy, and mass spectrometry were used to examine gaseous products of its thermal and thermooxidative destruction. It was found that the initial formation rate of aldehydes and carbon dioxide decreases in the course of thermostating of the fl uorine-containing composite polyester material. The method of thermogravimetry demonstrated that modified poly(ethylene terephthalate) has a higher thermal stability.     

Stabilization of dinitrosyl iron complexes under matrix isolation conditions: solvent and polymer effects on the synthesis of composites based on poly(methyl methacrylate) and iron complexes [Fe<Subscript>2</Subscript>(μ-NCS-R)<Subscript>2</Subscript>(NO)<Subscript>4</Subscript>]

Homogeneous composites based on poly(methyl methacrylate) and its copolymers with methacrylic acid and on the nitrosyl iron complexes with 2-mercaptobenzimidazole and 2-mercaptobenzthiazole were synthesized. An analysis of the experimental data obtained by the methods of small-angle X-ray diffraction and SQUID magnetometry in combination with the results of quantum chemical calculations showed that the nitrosyl complexes did not retain their initial binuclear structure under the matrix isolation conditions: some complexes decompose to mononuclear ones. The percentage ratio of the dimers and monomers depends on the fraction of the methacrylic acid copolymer in the polymeric matrix and is almost independent of the type of thiol ligand in the iron complex.     

Factors affecting convergence in LMTO calculations of the electronic structure of complex crystals

This paper considers factors affecting the convergence of linear muffin- tin (MT) calculations in the atomic sphere approximation (LMTO- ASA) for the case of polyatomic compounds. Recommendations on choosing the radii of MT spheres, the initial energies (centers of gravity of the occupied bands), and the initial distribution of the atomic density of the charge are given. Methods to separate the correct and discard the false self- consistent result are suggested using the calculations of MgO and NaCl as examples. These approaches were tested and gave good results for the compounds ScPd, ScRh, LiH, WC, TlBr, CaO, MgO, KBr, CuPd, NaCl, LiF, CaS, ZnO, Cu₂O, TiO₂, YBa₂Cu₃O₇, Tl₂CaBa₂Cu₂O₈. Translated fromZhumal Strukturnoi Khimii, Vol. 38, No. 4, pp. 616–624, July–August, 1997.     

Reductive electrocatalytic dehalogenation of nitrobenzyl halides: nitrophilic or halophilic attack?

Electrochemical reduction of Cp₂TiCl₂ in the presence of benzylic halides results in their catalytic dehalogenation to form toluene derivatives. Possible schemes for the process were proposed on the basis of the results of electrochemical studies and digital simulation data. The catalytic scheme including the halophilic attack of the Ti^III complex to organic halide as a key step occurs for unsubstituted benzylic halides. In the case of nitro-substituted substrates, the reaction is strongly accelerated. In this case, an electron transfer from the reduced form of the catalyst to the NO₂ group of organic halide is possibly accompanied by the intramolecular charge transfer to the C-Hal bond, thus facilitating its cleavage. Thus, the nitro group in the starting benzylic halide acts as a “redox antenna,” transferring an electron to the C-Hal bond. The proposed scheme is supported by semiempirical calculations of the geometry of molecular complexes with the Ti-Hal or Ti-NO₂ coordination.__________Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 1, pp. 196–205, January, 2005.     

Surface-induced shift of melting/freezing temperatures at interfaces between two semi-infinite media

Many physical properties and the structure of liquids at interfaces differ from those of the same liquids in the bulk state. In particular, the freezing temperatures of numerous liquid systems at interfaces between two fluids can be either increased or decreased compared to the temperature of corresponding bulk phase transition. The approach proposed in this paper allows one to predict the surface-induced shift of the melting/freezing temperatures in various systems. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 1, pp. 14–18, January, 2007.