ESR spectroscopic investigation of steric and polar factors in the addition of radicals to unsaturated compounds

The rate constants of the addition of CCl₃CH₂ClCH₃(R⁶) radicals to -methyl-styrene, styrene, methyl methacrylate, methyl acrylate, and acrylonitrile and of CCl₃CH₂(CH₃)₂(R⁷) radicals to styrene, methyl acrylate, and acrylonitrile were determined by ESR spectroscopy. It was shown that the radicals R⁶ and R⁷ possess approximately equal reactivity in addition to unsaturated compounds, despite the difference in the donor-acceptor properties of the substituents at the vinyl group. In a comparison of the reactivity of radicals R⁶ and R⁷ with the reactivity of radicals CCl₃CH₂H₂(R¹), CCl₃CH₂HCH₃(R³), CCl₃CH₂HCl(R⁴), and ClCH₂CH₂Cl₂(R⁵) [1] in addition reactions, it was shown that polar and steric effects of the substituents situated in the -position to the radical site of the above-mentioned radicals, as well as the donor-acceptor properties of the substituents at the vinyl group in the unsaturated compounds, lead to appreciable changes in reactivity.A. N. Nesmeyanov Institute of Heteroorganic Compounds, Russian Academy of Sciences, 117813 Moscow. Translated from Izvestiya Akademii Nauk, Seriya Khimicheskaya, No. 1, pp. 136–141, January, 1992.     

Ruthenium clusters containing the [2.2] paracyclophane ligand: Recent developments in arene-cluster chemistry

In this article we review the synthesis, reactivity, and characterization of a number of clusters bearing the [2.2] paracyclophane ligand with nuclearities ranging from two to eight. Particular attention is focused on the different coordination modes that paracyclophane adopts; these being µ₁- ⁶, µ₂- ³ : ³, µ₃- ¹ : ² : ², and µ₃- ² : ² : ². Structural modifications which take place within the ring system on bonding in these various modes are also discussed.     

A spin-trap ESR study of the decomposition of alkyl formates

Conclusions By using nitroso compound ESR spin traps it has been shown that the alkyl formates break down into radicals under irradiation at 2537 Å and 25°C, and this regardless of whether or not the system contains added tert-butyl peroxide. The mechanism of breakdown varies with the alkyl-formate structure, Under our conditions of irradiation, the product radicals were as follows: OOCH₃ from methyl formate; OOCH₂CH₃ and HCOOHCH₃ from ethyl formate; OOC(CH₃)₃ and (CH₃)₃ from tert-butyl formate.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 3, pp. 542–545, March, 1977.     

Cluster assisted formation of carbon-carbon bonds: Synthesis and crystal structures of two trinuclear heterometallic complexes CpWRu2(CO)7(μ-H)[OC(NMe2)CCHCHEt] and CpWRu2(CO)6(μ-H)[OC(NMe2)CCH(μ-η2-C6H4)]

Treatment of the carbamoyl cluster Ru₃(CO)₁₀(-H)(-²-OC(NMe₂)] with a two molar excess of CpW(CO)₃CCⁿ Pr in refluxing toluene produced a heterometallic cluster complex CpWRu₂(CO)₇(-H)[OC(NMe₂) CCHCHEt] (II), whereas the heterometallic clusters CpWRu₂(CO)₆(-H)[OC(NMe₂)CCH(-²-C₆H₃X)] (IVb, X=H;IVc, X=Me;IVd, X=F) were isolated from the reactions with CpW(CO)₃CCC₆H₄X under similar conditions. Both complexesII andIV were generated via a complicated sequence involving hydride migration to the acetylide, fragmentation of the cluster via removal of a Ru(CO)_n unit, coupling with the carbamoyl ligand and C-H bond activation at the substituent. Crystal data forII: space group R ;a=26.605(3),c=17.934(2) Å,Z=18; finalR _F =0.032,R _w =0.034 for 2720 reflections withI>2(I). Crystal data forIVb: space group C 2/c;a=16.120(6),b=14.972(2),c=18.872(4) Å, =95.46(2)°,Z=8; finalR _F =0.0375,R _w =0.0375 for 2074 reflections withI>3(I).     

Multinuclear macromolecule metal complexes 2. Preparation and characterization of Prussian blue and its analogs bonded to pofy(vinylamine hydrochloride)

Prussian blue and its analogs bonded to poly(vinylamine hydrochloride) (PVAm · HCl) containing Fe^II or Fe^III and M²⁺ (M=Fe, Co, Cu) in a 11 molar ratio were obtained by the reaction of [Fe(CN)₆] ^n– (n=3,4) with M²⁺ ion-PVAm · HCl mixture in aqueous solution. Under a limited polymer concentration (T_VAm/T_Fe over 10), these polymer complexes thus obtained were stable and soluble in water. By casting these solutions, colored films can be produced. The formation of Prussian blue and its analogs bonded to PVAm · HCl was also investigated by the Benesi-Hildebrand method. The molar extinction coefficients of intervalence charge transfer (Fe^IIFe^III, Co^IIFe^III, Fe^IICu^II) band for MFe(CN)₆]^(n–2)– bound to PVAm · HCl (M=Fe, Co, Cu) were found to be 10,100–9601 · mol^–1 · cm^–1 at 25 C. The formation constants were found to be in the range of 10⁷ to 10¹⁰ M^–1. The changes of enthalpy (H) and entropy (S) were found to be in the range of –10.4 to –22.5 kJ · mol^–1 and 5.7 to 52.9 J · K^–1 mol^–1 respectively, at 25C.     

Extraction of Polonium from Aqueous α-Hydroxyisobutyric Acid Solutions Using Dioctyl Sulphide, Cyanex 272, Cyanex 301 or Cyanex 302 in Toluene

A study of the extraction of polonium from aqueous solutions containing -hydroxyisobutyric acid (-HIBA) was performed with four different extractants, di-n-octyl sulphide (DOS), Cyanex 272, Cyanex 301 and Cyanex 302, dissolved in toluene. The extracted complex for DOS at low -HIBA concentrations is most likely PoO(-HIB)₂·2DOS, while at higher -HIBA concentrations there seems to be a solvating effect implicating an extracted complex of the type PoO(-HIB)₂(-HIBA)₂·2DOS. For the extraction of polonium with Cyanex 272 the results are inconclusive. The extracted complex is either PoOA₂ or PoO(-HIB)₂·2HA. For extraction with Cyanex 301 or Cyanex 302 the major extracted species does not contain any -HIBA molecules. The neutral species in both cases is PoOA₂, extracted at low extractant concentrations, while at higher extractant concentrations a complex of the type PoOA₂·xHA is extracted. The extraction of polonium increases in the order Cyanex 272 < DOS < Cyanex 302 < Cyanex 301.     

Kinetics of Detonation Initiation in the Supersonic Flow of the H2 + O2 (Air) Mixture in O2 Molecule Excitation by Resonance Laser Radiation

The possibility of initiating detonation in the supersonic flow of the H₂ + O₂ (air) mixture behind the front of the inclined shock wave by O₂ molecule excitation to the O₂(a ¹_g) and O₂(b ¹·⁺ _g) states by laser radiation with a wavelength _I = 1.268 m and 762 nm is considered. Resonance laser radiation intensifies chain combustion due to the formation of new pathways for generating active atoms O^· and H^· and radicals OH and has a substantially nonthermal character. Even at low (3 kJ/cm²) energies of radiation with _I = 762 nm applied to the gas, detonation combustion can occur even at a distance of 1 m from the front at the gas temperature as high as 600 K.     

Rate constants for addition of triethylsilyl radicals to spin traps

Conclusions The rate constants for the addition of triethylsilyl radicals to -phenyl-N-tert-butylnitrone (k_add=(11±5)·10⁶ liter/mole·sec) and 2,4,6-tri-tert-butylnitrosobenzene (k_add= (1.5±0.3)·10⁹ liter/mole·sec) at 20°C were determined by the EPR method.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 4, pp. 938–941, April, 1984.     

Preparation and characterization of a series of poly(acrylamide-co-acrylates), with a copolymer composition between 0–96.3 mol-% acrylate units with the same degree and distribution of polymerization

A series of linear poly(acrylamide-co-acrylates) (PAAm/AAcNa) has been prepared covering a copolymer composition between 0 and 96.3 mol% acrylate units, which have the same degrees of polymerization and chain length distributions. Measurements of viscosity and light scattering have proven that maximum coil dimensions of PAAm/ AAcNa in salt solutions are achieved at about 67 mole-% AAcNa. This so-called maximum behaviour was researched by measuring the radius of gyration, second virial coefficient, molecular weight, preferential solvation, viscosity and absorption bands of the copolymer series. Thus, an increase in the possible ways of arranging AAcNa-AAm-AAcNa units (via H-bonds) will lead to extended coil dimensions and therefore influence the viscosity. In addition, it can therefore be concluded from all these results that the maximum behaviour is real and not influenced by the different distributions of the samples. The copolymer composition can be easily determined by infra-red spectroscopy by use of a proposed relation.Abbreviations A₂ second virial coefficient (mole · cm³ · g^–2) - AAm acrylamide - AAcH acrylic acid - AAcNa sodium acrylate - c polymer concentration (g · cm^–3) - salt concentration (g · cm^–3), (Val · cm^–3) - C _LS critical concentration obtained by light scattering (g · cm^–3) - d _[] viscosity equivalent diameter of a sphere (nm) - E extinction - FW _s formula weights of salt - g _s gram of salt - g _p gram of polymer - GuaCl guanidinium chloride - h ^21/2 root mean square end-to-end distance (nm) - K optical constant for unpolarized incident light (mole · cm² · g^–2) - M molarity (mole · 1^–1) - M _w weight average molecular weight (g · mole^–1) - N _L Avogadro constant 6.023 · 10²³ mole^–1 - P _n number average degree of polymerization - P _w weight average degree of polymerization - PAAm poly(acrylamide) - PAAcH poly(acrylic acid) - PAAcNa poly(sodium acrylate) - PAAm/AAcNa poly(acrylamide-co-sodium acrylate) - R _[] Rayleigh ratio of the scattering at angle (cm^–1) - R _G ² _Z ^1/2 root mean square average radius of gyration (nm) - R _[] viscosity equivalent radius of a sphere (nm) - T temperature (°C), (K) - u excluded volume (cm³ · g^–1) - V molar volume (cm³ · mole^–1) - V _s partial specific volume - X mole fraction - (NH₂) oscillation of deformation - extinction coefficient - ₀ zero shear viscosity (Pa · s), (mPa · s) - _red reduced viscosity (cm³ · g^–1) - [] intrinsic viscosity (cm³ · g^–1) - _a constant of preferential solvation (g · g^–1) - ₀ wavelength of light in vacuo (nm) - chemical potential - v _as stretching vibration - scattering angle (°)     

Interesting synthetic routes from the reinvestigation of the reaction of the M(CO)6 (M=Cr,Mo and W) species with KOH

Summary Reinvestigation of the reaction of M(CO)₆ (M=Cr, Mo or W) with KOH has been found to provide a very convenient route to the K[M₂H(CO)₁₀] compounds (M=Cr, Mo or W). The reaction involving Cr(CO)₆ yields new potassium derivatives containing [Cr₂(CO)₁₀]^2– and [HCr(CO)₅]^– species; also K[Cr₂D(CO)₁₀] is produced from the Cr(CO)₆/KOD interaction in C₂D₅OD. The reaction involving two different group 6 metal carbonyls yields [MM(CO)₁₀(-H)]^– (MM=CrMo, CrW or WMo) species as their K⁺ and PPN⁺ [bis(triphenylphosphine)iminium] salts.     

Iron Catalysis of SO2 Oxidation in the Atmosphere

The mechanisms of SO₂ oxidation catalyzed by iron ions in the droplet phase of the convective cloud in the lower atmosphere were examined. The relations of the catalytic SO₂ decrease to the concentration of the iron ions and to the intensity of fluxes to the droplet of the OH _(g) and HO _2(g) radicals were characterized. The determining role of the replacement of the low-reactive HO _2(g)(O^– _2(aq)) radical by the reactive SO^– _5(aq) radical in the sulfite medium during daytime was revealed. This process occurred due to the coupling of the decay of the radicals and their regeneration in the liquid-phase reactions O^– _2(aq) + FeOH²⁺ _(aq) Fe²⁺ _(aq) + OH^– _(aq) + O_2(aq), HSO^– _5(aq) + Fe²⁺ _(aq) FeOH²⁺ _(aq) + SO^– _4(aq)HSO ₃ ^- _(aq),O_{2 (aq)} SO^– _5(aq).     

Photometrische Bestimmung von Sulfid mit Jodnitrotetrazoliumchlorid

Zusammenfassung S^2– kann mit Jodnitrotetrazoliumchlorid (INT) innerhalb von 30 min photometrisch bestimmt werden. PO₄ ^3–, Cl^– und SO₄ ^2– in Konzentrationen bis zu 5 · 10^–2 mol/l, S₂O₃ ^2– bis zu 10^–4 mol/l und S₃O₆ ^2– bis zu 2 · 10^– mol/l stören nicht. Die untere Bestimmungsgrenze beträgt 3,4 · 10^–5 mol/l, entsprechend 1 g S^2–. Als relative Standardabweichung ergibt sich bei der Bestimmung von 3,2 g S²}±6,4 Rel.%.Die Untersuchungen wurden mit Hilfe eines Stipendiums der Alexander von Humboldt-Stiftung durchgeführt, der an dieser Stelle herzlich gedankt sei.     

The supramolecular structures and reactivities of some complexes of chiral crown ethers with borane ammonia

Whereas 1 1 crystalline complexes have been isolated between borane ammonia and methyl 4,6-O-benzylidene-2,3-dideoxy--d-galactopyranosido [2,3-b]-1,4,7,10,13,16-hexaoxacyclo-octadecane (1), methyl 4,6-O-benzylidene-2,3-dideoxy--d-mannopyranosido [2,3-b] (methyl 4,6-O-benzylidene-2,3-dideoxy--d-mannopyranosido [2,3-k]-1,4,7,10,13,16-hexaoxacyclo-octadecane (3), and (1R,2R,7R,24R)-3,5,8,11,14,17,20,23,26,28-decaoxatricyclo-[21.4.0.0^2,7]octacosane (4), the hosts, methyl, 4,6-O-benzylidene-2,3-dideoxy--d-mannopyranosido[2,3-b] 1,4,7,10,13,16-hexaoxacyclo-octadecane (2) and 1,4 1,4 3,6 3,6-tetra-anhydro-2,2 5,5-bis-O-oxydiethylenedi-d-mannitol (5) have yielded 2 1 (guest:host) crystalline complexes with borane ammonia as guest. X-ray analyses of the supramolecular structures of BH₃NH₃ ·1, (BH₃NH₃)₂ ·2, BH₃NH₃ ·3, BH₃NH₃ ·4, and (BH₃NH₃)₂ ·5 have been carried out and BH₃NH₃ ·1, BH₃NH₃ ·2, and (BH₃NH₃)₂ ·5 have been shown to reduce acetophenone with enantiomeric excesses of 5, 13, and 10% respectively. Supplementary Data relating to this article (atomic coordinates of the hydrogen atoms and thermal parameters) are deposited with the British Library as Supplementary Publication No. SUP 82017 (74 pages).Dedicated to Professor H. M. Powell.     

Mass spectrometric study of the vacuum pyrolysis of perfluorohexene-2 and determination of the ionization potential of the perfluoro-2-buten-4-yl radical

The ionization potential (IP) of the perfluoro-2-buten-4-yl radical, generated at 950C and 1·10⁵ torr by vacuum pyrolysis of perfluorohexene-2, was found to be 10.3 ± 0.1 eV by the electron impact method. This value is close to the IP of the perfluoro radicals n-C₃F₇ (10.06 ± 0.1 eV) and i-C₃F₇ (10.5 ± 0.1 eV); however, it is 1.8 eV higher than that of the perfluoroallyl radical, possibly because of the weak delocalization of the unpaired electron. At pyrolysis temperatures above 800C, the perfluoro-2-buten-4-yl radical decomposed to the tetrafluoroallene and trifluoromethyl radicals.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 5, pp. 1220–1223, May, 1991.     

Gamma radiolysis of Methyl Red solution and reaction induced by γ-irradiated NaCl in Methyl Red

The -radiolysis of Methyl Red solution in HCl medium at pH=2 has been studied along with energy transfer reaction brought about byF and hole centers of -irradiated NaCl. The G-values for degradation of the azo dye indicator by radiolysis and -irradiated salt were determined as 9·10^–1 and 4.8·10^–3, respectively. The kinetic rate constants (k) of degradation are evaluated as 2·10^–5 rad^–1 in the case of direct radiolysis, while for the irradiated salt it is 2·10^–7 rad^–1. The extent of degradation by direct -radiolysis is 100–200 times greater as compared to that by the -irradiated salt. The same mechanism is proposed for radiolysis as well as the reaction induced by -irradiated sodium chloride.     

Electronic effects of the 1-[CLOSO-3,3,3-(CO)3-3,1,2-ReCaB9H10]− and 1-[CLOSO-3,3,3-(CO)3-3,1,2-.MnC2B9H10]- groups

Conclusions The electronic effects of the 1-[closo-3,3,3-(CO)₃-3,1,2-ReC₂B₉H₁₀]^– (_I=-0.066; _r ^o=0.101) and 1-[closo-3,3,3-(CO)₃-3,1,2-MnC₂B₉H₁₀]^–(_I=0.090; _r ^o=0.165) groups were determined by the Taft method.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 10, pp. 2296–2298, October, 1987.     

Ab initio investigation of the electron structure in bis-Cu+ acetylene and vinylidene complexes

[Cu(-C₂H₂)₂]⁺, [Cu(-CCH₂)₂]⁺ and [Cu(-C₂H₂) (-CCH₂]⁺ complexes have been studied by the ab initio double-zeta basis set method. It has been established that all calculated compounds are stable to decomposition into two C₂H₂ molecules and Cu⁺ cation and into one C₂H₂ molecules and the respective monocomplex. Calculation results suggest the possibility of intramolecular acetylene-vinylidene rearrangement in the coordination sphere of Cu⁺.

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ab initio : [Cu(-C₂H₂)₂]⁺, [Cu(-CCH₂)₂]⁺, [Cu(-C₂H₂) (-CCH₂)]⁺. C₂H₂ Cu⁺ C₂H₂ . - Cu⁺.

     

Komplexe des Nickels mit p-Methylbenzamidoxim

Zusammenfassung Die Komplexbildung des p-Methylbenzamidoxims (pMB) mit Ni²⁺ wurde in neutraler und alkalischer Lösung spektrophotometrisch untersucht. In neutraler Lösung wird ein grüner Komplex 11 gebildet, dessen Bildungskonstante ₁=1,12 ist. In alkalischer Lösung werden zwei Komplexe (11 und 12) gebildet mit Bildungskonstanten ₁=4·10⁵ und ₂=0,2.

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Nickel complexes with p-methyl benzamide oxime

The complex formation of p-methyl benzamidoxime with Ni²⁺ was studied spectrophotometrically in neutral and in alkaline solution. A green complex 11 is formed in neutral solution. Its formation constant is ₁=1.12. In alkaline solution two complexes (11 and 12) are formed. Their formation constants are ₁=4·10⁵ and ₂=0,2 resp.

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Mit 6 Abbildungen     

Sorption of gold, silver and mercury on cellulose

Summary Distribution coefficients of Au³⁺ on cellulose in 0.1 M NaNO₃ are rather high in the pH range 2 to 8 (D 5·10³ ml/g). They are appreciably lower in presence of NaCl or NaCN. Distribution coefficients of Ag⁺ are relatively low in 0.1 M NaNO₃, appreciably higher in presence of NH₄NO₃ (D 10³ ml/g in weakly acid media) and low in presence of NaCl, Na₂S₂O₃ or NaCN. Distrubution coefficients of Hg²⁺ are low in 0.1 M NaNO₃, and in presence of NaCN, but higher in 0.5 M NaCl (D 2·10² ml/ g). Responsible for the equilibria are mainly the special interactions between the predominant species with the sorbent under the given conditions, and less the complex equilibria in solution.

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Sorption von Gold, Silber und Quecksilber an Cellulose

Zusammenfassung Die Verteilungskoeffizienten von Au³⁺ an Cellulose in 0,1 M NaNO₃ sind ziemlich hoch im pH-Bereich 2 bis 8 (D 5·10³ ml/g). Sie sind erheblich niedriger in Gegenwart von NaCl oder NaCN. Die Verteilungskoeffizienten von Ag⁺ sind verhältnismäßig niedrig in 0,1 M NaNO₃, erheblich höher in Gegenwart von NH₄NO₃ (D 10³ mol/g in schwach saurem Medium) und niedrig in Gegenwart von NaCl, Na₂S₂O₃ oder NaCN. Die Verteilungskoeffizienten von Hg²⁺ sind niedrig in 0,1 M NaNO₃ sowie in Gegenwart von NaCN, aber höher in 0,5 NaCl (D 2·10² ml/g). Verantwortlich für die Sorption sind in erster Linie die speziellen Wechselwirkungen der vorherrschenden Spezies mit dem Sorbens unter den gegebenen Bedingungen, weniger die Komplexbildungsgleichgewichte in Lösung.

     

The dependence of build-up233U,232U,233Pa and fission products from ThO2 irradiated in HFETR on integral thermal neutron fluxes and neutron spectra

In this paper the dependence of build-up²³³U,²³²U,²³³Pa and fission products from ThO₂ irradiated in HFETR on integral thermal neutron fluxes and neutron spectra have been investigated. The yields of all above nuclides in ThO₂ increase with the increase of integral thermal neutron fluxes at different neutron spectra. The values of²³³U/²³²Th increase with the increases of _th and decreases with the increase of fast/thermal neutron ratios (_f/_th). The values of²³²U/²³³U increase with the increase of both _th and _f/_th ratio. The amount of fission products relative to original irradiated thorium decreases with the increase of _f/_th ratios. These results could be used to evaluate the behaviour of thorium-based nuclear fuel in reactor.