Spin-adducts of η2-metallocomplexes of fullerene-60 with phosphoryl radicals

Using ESR spectroscopy, the reaction of P(O)(OPrⁱ)₂ phosphoryl radicals with C₆₀ML₂ (M=Pd, Pt) was studied and the spin-adducts formed were shown to be unstable under the reaction conditions. The ⁵-addition of Pt(PPh₃)₄ to the dimer of phosphorylfullerenyl radicals results in metal-containing dimers (RO)₂(O)PL₂MC₆₀-C₆₀ML₂P(O)(OR)₂, which dissociate when exposed to visible light to afford C₆₀ML₂P(O)(OR)₂ radicals; ML₂ in these complexes is located in different positions in relation to the radical center. As a result, the ESR spectra contain the superposition of at least five signals of radicals that differ in HFS constants andg-factors.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 5, pp. 938–940, May, 1994.The present work was supported by the Russian Foundation for Basic Research (Projects 93-03-18725 and 93-03-4101).     

Research in the isoxazole series. 38. Polarographic reduction of 4-arylazoisoxazoles

The indicated compounds are reduced on a dropping-mercury electrode in aqueous alcohol solutions at pH > 7 in one two-electron wave to 1,2-disubstituted hydrazines; four-electron reduction with the formation of amines takes place in acidic media. Two one-electron reduction waves are observed in dimethylformamide (DMF). Satisfactory E_1/2– correlation equations were obtained for 4-arylazo-3,5-dimethyloxazoles.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1320–1323, October, 1980.     

Effect of Water Vapor on Chromatographic Characteristics of the Cyclodextrin-Containing Stationary Liquid Phase in Capillary Gas Chromatography

The effects of the presence of water vapor in the carrier gas and the temperature on the retention of achiral and chiral compounds, enantioselectivity, and performance of an open-tubular column with a cyclodextrin-containing phase were studied. The use of a carrier gas containing water vapor in the determination of optically active isomers, such as camphor, slightly increases the retention factor. A substantial improvement of performance characteristics of the column was found: for hydroxy compounds, the column performance increased by two to three times and the peak symmetry improved by more than twice.     

Fast 3D shape screening of large chemical databases through alignment-recycling

Background  

Large chemical databases require fast, efficient, and simple ways of looking for similar structures. Although such tasks are now fairly well resolved for graph-based similarity queries, they remain an issue for 3D approaches, particularly for those based on 3D shape overlays. Inspired by a recent technique developed to compare molecular shapes, we designed a hybrid methodology, alignment-recycling, that enables efficient retrieval and alignment of structures with similar 3D shapes.     

X-ray study of the molecular structure of α-mercury and α-platinummercury derivatives of l-menthyl phenylacetate

The molecular structures of the L-menthyl ester of S-α-bromomercuriphenyl-acetic acid, diastereomer II, [α]²⁰_D ?18°, and of the related L-menthyl ester of α-bromobis(triphenylphosphine)platinummeruriphenylacetic acid, VI, have been investigated by the X-ray method. Insertion of L₂Pt carbenoid appears to occur into the HgBr bond in II and two phosphine ligands in the product VI occupy cis positions in a planar square around the platinum atom. The HgPt distance is 2.50 Å; there is intermolecular HgBr coordination in II, the distance being 3.23 Å.     

Isotope exchange study of the e lectrophilic replacement reaction in a saturated carbon atom

Summary A study of the isotope exchange of the ethyl esters of -brommercuryarylacetic acids with²⁰³Hg Br₂ and 70% aqueous dioxane at 60°, made it possible to arrange the substituents in the following series in order of decreasing reaction rate: p-I, Br, Cl > p-F >H > o-CH₃ > p-CH₃> p-typet. C₄H₉.     

Inclusion of Two PhP(O)(OH) 2 Guest Molecules into the Cavity of Macrocyclic Cavidand Cucurbit[8]uril

A new inclusion compound which is a supramolecular adduct of cucurbit[8]uril with two guest molecules of phenylphosphonic acid, PhP(O)(OH)₂, included into the cavity as ``two guests in host'' is reported. The guests match both size and hydrophilicity/hydrophobicity requirements. Two phenyl groups of molecules of PhP(O)(OH)₂ are directed toward the center of the large hydrophobic cavity whereas the PO(OH)₂ groups are outward-looking and bound with each hydrophilic portal of cucurbit[8]uril by a short hydrogen bond.     

Voltammetric studies of the Kolbe synthesis with perfluorocarboxylic acids prepared from hexafluoropropene oxide oligomers

Carboxylic acids prepared from hexafluoropropene oxide CF₃CF₂CF₂O[CF(CF₃)CF₂O]_nCF (CF₃)COOH [n = 0, 2,5-bis(trifluoromethyl)-3,6-dioxaperfluorononanoic acid; n = 1, 2,5,8- tris(trifluoromethyl)-3,6,9-trioxaperfluorododecanoic acid], according to voltammetric data, enter the Kolbe reaction both at the Pt anode and at anodes from carbon materials in H₂O-CH₃CN and CH₃OH-CH₃CN solutions. The critical potential appreciably depends both on the anode material and on the solvent composition. Favorable effect of pyridine additions in H₂O-CH₃CN solutions is due to replacement of water molecules from the electrical double layer. The sodium ions exert a negative effect on the Kolbe synthesis.Translated from Zhurnal Obshchei Khimii, Vol. 74, No. 11, 2004, pp. 1842–1846.Original Russian Text Copyright © 2004 by Chechina, Sokolov, Tomilov.This revised version was published online in April 2005 with a corrected cover date.     

The multidipole effect in reactions of polyfunctional peroxy radicals

Conclusions The rate constant of the reaction of peroxide radicals of acrylic and methacrylic esters of polyols with nonpolar cumene is not dependent on the number of ester groups, and with polar 2,4,6-tri-tert-butylphenol decreases with an increase in the number of ester groups in the peroxide radical. Both findings are in agreement with the model of a dipole-dipole interaction in reactions of polyfunctional compounds.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 4, pp. 778–781, April, 1985.