Electrocatalytic multicomponent cyclization of aromatic aldehydes,malononitrile, and malonates into 3-substituted 2,2-dicyanocyclopropane-1,1-dicarboxylates

Electrolysis of aromatic aldehydes, malononitrile and malonates in methanol in an undivided cell in the presence of double-mediator system NaBr-NaOAc afforded 3-substituted 2,2-dicyanocyclopropane-1,1-dicarboxylates in 40–60% yields.     

New photochemical transformations of 1-iodopropan-2-one

Photolysis of 1-iodopropan-2-one (λ = 254 nm) at 80–90°C in the absence of CCl₄ was studied. The structure of obtained polymer was studied by ¹H NMR, IR, and ESR spectroscopy.     

Alkylation of 2-methylimidazole with iodomethylsilanes

2-Methyl-1,3-bis[(1-methylsilolan-1-yl)methyl]-1H-imidazolium triiodide, 1,3-bis{[dimethyl-(phenyl)silyl]methyl}-2-methyl-1H-imidazolium iodide and triiodide, and cyclic 3,3,5,5,10-pentamethyl-4-oxa-7-aza-1-azonia-3,5-disilabicyclo[5.2.1]deca-1(10),8-diene iodide were synthesized by solvent-free reactions of 2-methyl-1H-imidazole with 1-(iodomethyl)-1-methylsilolane, (iodomethyl)(dimethyl)phenylsilane, and ethynyl(iodomethyl)(dimethyl)silanes, respectively, in the absence of base catalyst.     

Study of the mechanism of formation of heterocyclic disulfonium dications from 1,3-benzothiazole-2-thiol and 1-iodopropan-2-one

The potential energy surface for the formation of heterocyclic disulfonium dications from 1,3-benzothiazole-2-thiol and 1-iodopropan-2-one has been analyzed at the DFT B3LYP level of theory. The reaction involves oxidation of 1,3-benzothiazole-2-thiol to the corresponding disulfide, followed by alkylation of the exocyclic sulfur atoms. Stabilization of the salt with iodide anion is initiated by thermodynamically controlled reaction with molecular iodine, leading to the formation of stable structure with triiodide anion.     

The concentration metamagnetic transition in Tm1−x TbxCo2 compounds

The Tm_1?x Tb_xCo₂ (0 ≤ x ≤ 1) system was studied by measuring the magnetic susceptibility, electrical resistance, and neutron diffraction. In the compounds with 0 < x ≤ 0.15, an inhomogeneous magnetic state characterized by the existence of large regions (up to 100 Å in size) with short-range ferrimagnetic order was found to occur. The maximum of the residual electrical resistance observed in the compound with x = 0.1 at the magnetic ordering temperature was established to be due to the scattering of conduction electrons by localized spin fluctuations associated with f-d exchange fluctuations caused by the substitution of terbium for thulium. The increase in the terbium concentration to x ≥ 0.15 leads to a sharp increase in the Co sublattice magnetization and the establishment of a long-range ferromagnetic order, which indicates a concentration metamagnetic transition in the band subsystem.     

Metamagnetic phase transition in Nd1−x TbxCo2 compounds

The electric resistivity and neutron diffraction measurements of the intermetallic compounds Nd_1?x Tb_xCo₂ (x = 0, 0.2, 0.3, 0.5, 0.7, or 1) have been performed. All compounds have a cubic structure at room temperature and a rhombohedral structure at 4.2 K. The magnetic structure of these compounds is described by the wave vector k = 0. The magnetizations of the rare earth and cobalt sublattices increase with increasing x. The concentration dependence of the cobalt sublattice magnetization is explained on the basis of the model of metamagnetic band subsystem in compounds of the RCo₂ type.     

Investigation of the spin-glass state in γ-Fe-Ni-Mn alloys

The composition region where there are no long-range ferro- and antiferromagnetic order has been determined in γ-Fe-Ni-Mn alloys. In these alloys strong small-angle magnetic neutron scattering has been obtained. The intensity has an unusual temperature dependence which is discussed in the framework of the critical neutron scattering thermodynamic theory. The ground state of these alloys is identified with the spin-glass state in which there are also regions of both short-range ferro- and antiferromagnetic order.