A. A. Khodak

Conformational isomerisin of phosphorus-containing fullerenyl radicals

ESR spectra of phosphorus-containing fullerenyl radicals.C60-P(O)(OPr1)2 and. C60-P(O)(OEt)Ph were studied at low temperatures (193–273 K). A decrease in the rate of rotation of organophosphorus group around the C-P bond results first in line broadening and then in the appearance of two doublets due to two “extreme” conformations, which have differentg-factors and hyperfine coupling constants (HCC) of the unpaired electron with the31P nucleus. The kinetic and thermodynamic parameters of the conformational isomerism were calculated.

Regularities of self-propagating high-temperature synthesis in the solid 8-hydroxyquinoline—chloramine B system

The regularities of chemical reactions in solid 8-hydroxyquinoline—chloramine B mixtures were studied under conditions of organic self-propagating high-temperature synthesis (SHS), isothermal reaction, and thermal explosion in the 20–220 °C temperature range. Comprehensive physicochemical analysis and microstructural study of the reaction products were carried out. The temperature of SHS initiation (58 °C), the heat of the reaction (129±9 kJ mol−1), the stoichiometric coefficient (1), the maximum temperature (Tmax=98–140 °C), and the velocity of SHS wave propagation (u=0.15–0.55 mm s−1) were determined. Depending on the ratio of the reactants (n), a low-temperature non-degeerate stable gasless mode (n≤1,Tmax=115 °C,Ea=42 kcal mol−1) and a high-temperature mode (n>1,Tmax=140 °C,Ea=0.4 kcal mol−1) are possible for SHS. The SHS affords monohydroxy and monochloro derivatives of 8-hydroxyquinoline, benzenesulfonamide, NaCl, NaOH, and H2O. The mechanism of the solid-phase reaction at temperatures below 58 °C includes surface, solid-phase, and gas-phase diffusion; that for SHS is capillary spreading of the hydroxyquinoline melt.

Molecular structure of the dimeric complex of copper (II) chloride with triphenyl-N-[6-methylpyridyl-2]phosphinimine

The complex of copper(II) dichloride with triphenyl-N-(6-methylpyridyl-2)phosphinimine has been studied by X-ray diffraction. This compound has a dimeric structure with two μ2-bridge chlorine atoms. The coordination of copper atoms by three chlorine atoms and the N atom of the heterocycle is of a strongly distorted planar-square type. A peculiar feature of this structure is the presence of intramolecular contacts Cu...N (2.504 Å and 2.492 Å) involving the imine nitrogens of the P,N-containing ligands which are responsible for strong additional coordination of the copper atoms. In methanol the P,N-containing ligand forms a complex with Cu(II) where the metal-to-ligand ratio is equal to 1∶2. The ESR data point to the bidentate nature of the ligand in solution, where all four nitrogen atoms, contributed by both of the ligands, are located in the plane of the metal atom.

Protonation of triethyl (2-pyridylimido)phosphates

Protonation of triethyl (2-pyridylimido)phosphates has been studied by potentiometric titration in nitromethane, IR and NMR spectroscopy, and X-ray structure analysis. The substances studied are protonated in one step at the N-atom of the pyridine ring. The protonated cations may be represented, according to the X-ray data, as a resonance of two structures: pyridinium and pyridoniminium; the contribution of the latter probably being considerable. Changes in spectral parameters of POEt groups upon protonation of pyridylimidophosphates (PIP) have been noted.

Study of disproportionation of some substituted 2-Hydroxyphenoxyl radicals

Conclusions1.The activation energy for disproportionation of semiquinone radicals is close to zero, while the kinetic isotopic effect is KH/kD≈10; a kinetic scheme which explains these mechanisms was proposed.2.The heat of formation of a quinhydrone complex in the reaction of quinones and hydroquinones is approximately -5 kcal/mole, the heat of formation of semiquinone radicals is ∼10 kcal/mole, and the heat of formation of a quinhydrone complex from the latter is ∼-15 kcal/mole.

Self-propagating high-temperature synthesis in the solid-phase triphenylphosphine-chloramine system

The macrokinetics and products of self-propagating high-temperture synthesis (SHS) in the solid-phase triphenylphosphine—chloramine system were studied by TGA-DTA, XRD, and31P NMR techniques. The temperature of SHS ignition (59°C), the velocity of reaction waves (1.6–5.0 mm s−1), and the maximum temperature (155–239°C) in the SHS wave were measured. The chemical composition of the product obtained was established: phosphine oxide, triphenyl-N-(phenylsulfoyl)-phosphinimine, benzenesulfonamide, NaCl, and water. The scheme of chemical reactions occurring during SHS was proposed.

Crystal and molecular structure of 1:1 molecular complexes of triphenyl-N-(4-methylpyridyl-2)phosphinimine and triphenyl-N-(3-methylpyridyl-2)phosphinimine with perchloric acid

X-ray diffraction analysis has been used to determine the crystal structures of the 1:1-composition products of protonation by perchloric acid of isomeric triphenyl-N-(4-methylpyridyl-2)phosphinimine (1) and triphenyl-N-(3-methylpyridyl-2)phosphinimine (2). The structures were refined toR=0.048 andR=0.052, respectively, using 2274 (1) and 2647 (2) reflections. The protonation centers are located at the sites of N atoms of the pyridine ring (1) and the phosphinimino group (2). The distribution of the bond lengths in the cations suggests that a significant contribution is made by a phosphonic structure with positive charges localized on the P atoms. N-H...O hydrogen bonds, with lengths of 2.890(4) and 3.020(3) Å, connect cations and anions in both structures.

Structural features of the copper(II) chloride-triphenylphosphine-N-(2-pyrimidyl)imine complex in crystal and solution

The structure of the copper(II) chloride-triphenylphosphine-N-(2-pyrimidyl)imine complex in crystal and solution was investigated by x-ray analysis and EPR. It was found that despite the difference in the structures of the dissolved and crystalline complexes, the exocyclic nitrogen atom is contained in the coordination sphere of the metal together with the nitrogen atom of the heterocycle in both cases due to the electronic effect of the phosphorus atom. In the crystal, the copper atom is coordinated with two chlorine atoms and two molecules of the ligand, and the distance from the copper cation to the nitrogen atoms of the pyrimidine rings is significantly less than the distance to the nitrogen atoms of the phosphinimine groups (2.0 and 2.8 Å, respectively). The coordination polyhedron formed as a result is a strongly distorted axially asymmetric octahedron. In dissolution, the chlorine anions are substituted by molecules of the solvent, the complex acquires axial symmetry, and four nitrogen atoms from two ligands form a planar square with a copper(II) cation in the center.

EPR of complexes of divalent copper ions with organophosphorus derivatives of 2-aminopyridine

The complexation of copper(II) ion with organophosphorus derivatives of 2-aminopyridine was studied with EPR. It was found that, compared with 2-aminopyridine, the presence of a P-N bond in its derivatives substantially changes the character of the coordination of the ligand with respect to divalent copper, which includes an aminic nitrogen atom in the coordination sphere of the metal, and results in the formation of a four-membered chelate ring. The parameters of the EPR spectra and evaluations of the stability constants are given.

Reaction of phosphonyl radicals with substituted orthobenzoquinones

ConclusionsThe reaction of a diethylphosphonyl radical with substituted orthobenzoquinones proceeds in two directions: addition to an oxygen atom, to form a phenoxyl-type radical, or to the ring, to form a cyclohexadienyl-type radical.