L. A. Aslanov

Vanadium peroxocomplexes as oxidation catalysts of sulfur organic compounds by hydrogen peroxide in bi-phase systems

Abstract New vanadium oxodiperoxocomplexes Bu4N+[VO(O2)2 L2]− were synthesized, where L=pyridine (1), 2-methylpyridine (2), 4-methylpyridine (3), 2-oxymethylpyridine (4). All complexes were characterized by NMR ( 1 H , 51 V ) and IR spectroscopy. The oxidation of sulfur organic compounds and diesel fuel desulfurization catalyzed by vanadium peroxocomplexes in bi-phase system was investigated in various solvents. The complexes manifested high catalytic activity and selectivity in oxidation of sulfides.

The mutual influence of ligands and the nature of chemical bonds in tin(IV) octahedral complexes

Abstract By considering the bond length Sn-Lig, determined by X-ray structure analysis in cis- and trans-complexes of general formula (CH3)nSnHal4 − n · 2 D, where n = 0–2, Hal = Cl or Br, D = hexamethylphosphoric triamide, dimethyl sulphoxide or dimethyl formamide, it was observed that in all complexes the tin atom is surrounded by ligands in a slightly deformed octahedral. The interactions of ligands in the considered complexes differ strongly from the interactions of ligands in octahedral and quadratic complexes of transition metals. All bond lengths are in good agreement with contributions from HVI, HVII hypervalent and covalent bonds in the formations of SnLig bonds and also with the participation of the 5d-orbital of tin.

The trans-strengthening of the SnO bond in six-coordinated complexes of tin(IV): Crystal and molecular structures of SnI4·2DPSO and C2H5SnI·2DPSO

An X-ray study of SnI4·2diphenylsulphoxide and EtSnI3·2diphenylsulphoxide indicates octahedral geometry for all the tin atoms in both complexes, the two DPSO ligands being cis to each other and in the second complex the ethyl group being trans to one of the DPSO ligands. In the second complex, under the influence of the ethyl group lengthening of the cis SnI bonds by 0.06 A and shortening of the trans SnO bond by 0.06 A occur. The mutual dependence of the SnO and OS bond distances is noted.

Trans-Strengthening in tin(IV) anionic complexes

Abstract X-Ray studies of (NMe 4 ) 2 EtSnCl 5 , (NMe 4 ) 2 BuSnBr 5 and (NMe 4 ) 2 SnBr 6 indicate octahedral geometry for all the tin atoms. In the first two complexes, under the influence of the alkyl group, the cis -Sn—Hal bonds are lengthened by 0.11 A (Hal = Cl) and 0.09 A (Hal = Br), while the trans -Sn—Hal bonds are shortened by 0.03 A (Hal = Cl) and 0.05 A (Hal = Br).

X-ray analysis and computer modeling of the structure of 'relaxor' ferroelectrics Pb3MgNb2O9 and Pb2ScTaO6 in the paraelectric state

A structural study of Pb3MgNb2O9 and ordered Pb2ScTaO6 single crystals is made by X-ray diffraction at high temperatures. Displacements of the Pb atom from the special site are clearly observed. Disordered atomic positions are uniformly distributed over a sphere with radius 0.2–0.3 A and with center at the special position. These atomic displacements are probably caused by local fields due to random statistical distribution of the (Mg, Nb) atoms in Pb3MgNb2O9 and, partially, the (Sc, Ta) atoms in Pb2ScTaO6. Computer modeling, based on the total-energy-minimization method, gives satisfactory agreement with experimental results.

Double stabilization of nanocrystalline silicon: a bonus from solvent

Double stabilization of the silicon nanocrystals was observed for the first time by 29Si and 13C MAS NMR spectroscopy. The role of solvent, 1,2-dimethoxyethane (glyme), in formation and stabilization of silicon nanocrystals as well as mechanism of modification of the surface of silicon nanocrystals by nitrogen-heterocyclic carbene (NHC) was studied in this research. It was shown that silicon nanocrystals were stabilized by the products of cleavage of the C–O bonds in ethers and similar compounds. The fact of stabilization of silicon nanoparticles with NHC ligands in glyme was experimentally detected. It was demonstrated that MAS NMR spectroscopy is rather informative for study of the surface of silicon nanoparticles but it needs very pure samples.Graphical Abstract

Stabilization of silicon nanoparticles by carbenes

Sodium reduction of a mixture of tetrabromosilane with imidazole ionic liquids in organic solvents gives dispersions of silicon nanoparticles stabilized by carbene ligands. It was shown that the size of silicon nanoclusters depends on the size of substituents at nitrogen atoms of 1,3-dialkylimidazol-2-ylidenes.

Crystal and molecular structures of complexes of diethyldibromotin with triphenylphosphine oxide and hexamethylphosphoric triamide

The crystal and molecular structures of the Et/sub 2/SnBr/sub 2/ x 2TPPO complex and two crystal modifications of the Et/sub 2/SnBr/sub 2/ x 2HMPT complex were determined by x-ray diffraction analysis. The complexes are mononuclear, and the coordination polyhedron of the tin atom is a slightly distorted octahedron. The regularities of cis weakening of the Sn-Br and Sn-O bonds under the influence of donor ethyl groups were ascertained.

Synthesis and structure of oxovanadium(IV) complexes [VO(Acac)(2)] and [VO(Sal : L-alanine)(H2O)]

AbstractBis(acetylacetonato)oxovanadium C10H14O5V (I) and (S)-[2-(N-salicylidene)aminopropionate]oxovanadium monohydrate C10H9NO5V (II) are synthesized. The crystal structures of compounds I and II are determined using single-crystal X-ray diffraction. Crystals of compound I are triclinic, a = 7.4997(19) Å, b = 8.2015(15) Å, c = 11.339(3) Å, α = 91.37(2)°, β = 110.36(2)°, γ = 113.33(2)°, Z = 2, and space group