10034-85-2

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Infrared absorptions of iodine and bromine atoms in solid rare-gases are presented. The isolated atoms are produced by UV-photolysis of HI or HBr in solid Ar, Kr and Xe. The absorptions are characterised by sharp zero-phonon lines and broad structured phonon side bands. Some of the zero-phonon lines are resolved and split into two components, separated by a few wavenumbers. The production of the atoms follow second-order kinetics indicating that the primary hydrogen atom undergoes a secondary reaction with the hydrogen halide producing a halogen atom and a hydrogen molecule. This is supported by the observation of the infrared absorptions of hydrogen molecules in concentrated matrices after photolysis.

The radicals formed by the reaction of GeH4 with H in the Xe matrix were investigated by electron spin resonance (ESR) spectroscopy at very low temperatures.The radicals observed were identified as GeH3 and GeH5.The newly observed radical GeH5 is consider

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The reaction between azide radicals (N3) and Br atoms is shown to produce electronically excited NBr(a1Δ) molecules in a room temperature flow reactor. This chemical system provides adequate concentration of NBr(a1Δ) so that this molecule can be systematically studied. The yield of NBr(b1Σ+) is minor. The quenching reactions of NBr(a) with HCl, HBr, HI, NH3, Br2, CF2Br2, and O2 were examined; the rate constants are (22 ± 5) × 10-14, (280 ± 30) × 10-14, (2300 ± 200) × 10-14, (35 ± 3) × 10-14, (2600 ± 300) × 10-14, (37 ± 6) × 10-14, and (230 ± 30) × 10-14 cm3 molecule-1 s-1, respectively.

In an attempt to provide confirmation for the postulated mechanism of O2 reduction in vanadium-mediated oxidative polymerization of diphenyl disulfide, a series of divanadium complexes containing salen ligand (salen = N,N′-ethylenebis(salicylideneamine)) were prepared, characterized, and subjected to reactivity studies toward dioxygen. A divanadium(III, IV) complex, [(salen)VOV(salen)][I3] (II), was yielded both by treatments of solutions of [(salen)VOV(salen)][BF4]2 (I) in acetonitrile with excess tetrabutylammonium iodide and by electroreduction of I followed by anion exchange with tetrabutylammonium triiodide. The complex II was characterized by a near-infrared absorption at 7.2 × 103 cm-1 (∈ = 60.1 M-1 cm-1 in acetonitrile) assigned to an intervalence transfer band. A crystallographically determined V(III)-V(IV) distance of 3.569(4) A? is consonant with the classification of II as a weakly coupled Type II mixed-valence vanadium (α = 3.0 × 10-2). Oxidation of the cation [(salen)VOV(salen)]+ with O2 in dichloromethane yielded spontaneously the deep blue, mixed valent, divanadium(IV, V) species [(salen)VOVO(salen)]+ which was structurally characterized both as its triiodide (III) and perchlorate (IV) salts. Crystal data for III: triclinic space group P1 (no. 2), a = 14.973(2) A?, b = 19.481(2) A?, c = 14.168(2) A?, α = 107.00 (1)°, β= 115.56(1)°, γ = 80.35(1)°, V = 3561.3(9) A?3, Z = 4, Dcalc = 1.953 g/cm3, μ (MoKα) = 31.74 cm-1, final R = 0.057 and Rw = 0.065. Crystal data for IV: triclinic space group P1 (no. 2), a = 11.923(3) A?, b = 14.25(1) A?, c = 11.368(7) A?, α = 112.92(5)°, β = 92.76(4)°, γ = 99.13(4)°, V = 1743(1) A?3, Z = 2, Dcalc = 1.537 g/cm3, μ (CuKα) = 57.69 cm-1, final R = 0.042 and Rw = 0.061. The complexes III and IV were deoxygenated in strongly acidic nonaqueous media to produce [(salen)VOV(salen)]3+ as a high-valent complex whose reversible two-electron redox couple (VOV3+/VOV+) at 0.44V vs Ag/AgCl has been confirmed. Its ability to serve as a two-electron oxidant provided a unique model of a multielectron redox cycle in oxidative polymerization.

The coordination compounds of group 12 halides with 2,2′-bipyridine (bpy) and 1,10-phenanthroline (phen), 2[CdF2(bpy)2]·7H2O (1), [ZnI(bpy)2]+·I3 ? (2), [CdI2(bpy)2] (3), [Cd(SiF6)H2O(phen)2]·[Cd(H2O)2(phen)2]2+·F–·0.5(SiF6)2–·9H2O (4), [Hg(phen)3]2+·(SiF6)2–·5H2O (5), [ZnBr2(phen)2] (6), 6[Zn(phen)3]2+·12Br–·26H2O (7) and [ZnI(phen)2]+·I– (8), have been synthesized and characterized by X-ray crystallography, IR spectroscopy, elemental and thermal analysis. Structural investigations revealed that metal : ligand stoichiometry in the inner coordination sphere is 1 : 2 or 1 : 3. A diversity of intra- and intermolecular interactions exists in structures of 1–8, including the rare halogen?halogen and halogen?π interactions. The thermal and spectroscopic properties were correlated with the molecular structures of 1–8. Structural review of all currently known coordination compounds of group 12 halides with bpy and phen is presented.

The reactions of the closo-decaborate anion with hydrogen halides and dichloroethane have been studied. Irrespective of the hydrogen halide used (HCl, HBr, HI), chlorination to give mono-, di-, and trihalosubstituted products is the major process. The product ratio depends on the hydrogen halide used and on the synthesis temperature and time. The products have been identified by 11B NMR, IR, and ESI mass spectra. The structure of (Ph 3(NaphCH2)P)2B10H8Cl 2 has been studied by X-ray diffraction. The geometry distortion of the closo-decaborate core found in the chlorinated derivatives is retained on further chemical transformations of the compound.

The complexation and reactions of molecular iodine with dimethyl sulfoxide and diethyl sulfoxide in the neat sulfoxides and in their mixtrues with water were studied by conductometry, pH-metry, argentometric titration, UV spectroscopy, and GLC analysis. According to the results obtained, molecular iodine initially forms a charge-transfer complex with the sulfoxide, which subsequently undergoes chemical transformations to hydrogen iodide and the corresponding sulfones. A possible reaction mechanism was suggested.

The photochemistry of (HI)m···(CO2)n (m, n = 1, 2, ...) complexes trapped in solid parahydrogen was studied by Fourier transform infrared absorption spectroscopy. Photolysis of the HI in the HI···(CO2)n/su

The photochemistry at a gas-liquid interface was investigated by time-of-flight/quadrupole mass spectroscopy (TOF/QMS). A thin liquid film of 4-iodobenzoic acid (IBA), dissolved in glycerol, was irradiated with nanosecond laser pulses at 275 nm. Atomic and molecular iodine were the only photoproducts leaving the liquid after a low-fluence laser pulse (2). The amount of released I atoms was 2 orders of magnitude larger than the amount of desorbed I2. Model calculations were carried out that take into account laser photolysis of IBA, diffusion, and surface evaporation of I and I2, and the condensed-phase kinetics of radical reactions. Ejection of hyperthermal I atoms by direct photodissociation of surface layer molecules is also considered. The quantitative analysis is restricted to low laser fluence conditions at which laser-induced heating of the illuminated liquid is negligible. The results of the model calculations were compared to previously obtained TOF data of an alkyl iodide (C18H37I) dissolved in the apolar liquid squalane (C30H62). The velocity distribution of the iodine atoms from the alkyl iodide solution corresponds to the temperature of the liquid (278 K). The contribution of I atoms from depths greater than 1 nm is large (>99%). In contrast, I atoms desorbing from IBA/glycerol are hyperthermal (Ttrans=480 K) and originate almost exclusively from the topmost molecular layer (1 nm). TOF measurements with a fast chopper wheel in front of the surface provide the time-dependent desorption flux from the surface and confirm that the contribution from deeper layers in the alkyl iodide solution is much larger than in the aryl iodide solution. Model calculations predict the behavior of the two solutions correctly if differences in caging of the geminate pair, diffusion coefficients of the free radicals, and the set of bulk radical reactions in the two solutions are taken into account. The hyperthermal energies of the ejected I atoms from the IBA solution are discussed in terms of the surface orientation of excited IBA molecules. The dependence of the TOF spectra on laser power and IBA concentration is interpreted by a surface excess of IBA. The result is compared to temperature-dependent surface tension measurements of IBA solutions in glycerol and water. The response of the surface tension to an accumulation of IBA at the surface is very weak.

Biohazards and chemical hazards as well as radioactive hazards have always been a threat to human health. The search for solutions to these problems is an ongoing worldwide effort. In order to control biohazards by chemical methods, a synthetically useful fused tricyclic iodine-rich compound, 2,6-diiodo-3,5-dinitro-4,9-dihydrodipyrazolo [1,5-a:5′,1′-d][1,3,5]triazine (5), with good detonation performance was synthesized, characterized, and its properties determined. This compound which acts as an agent defeat weapon has been shown to destroy certain microorganisms effectively by releasing iodine after undergoing decomposition or combustion. The small iodine residues remaining will not be deleterious to human life after 1 month.

The attachment of electron on HI and DI was studied in the 48-170 K range using the CRESU (Cinetique de Reaction en Ecoulement Supersonic Uniforme) technique. The attachment to HI was found to be exothermic and was expected to be fast and to proceed at a rate closed to the capture limit. The attachment to DI was found to be endothermic, where a positive temperature dependence was expected to occur if the electrons were thermal. A model, based on electron heating by superelastic collisions with the buffer gas was proposed.

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Four iodobismuthates, LiBiI4·5H2O (1), MgBi2I8·8H2O (2), MnBi2I8·8H2O (3), and KBiI4·H2O (4), were prepared by a facile solution route and revealed thermal stability in air up to 120 °C. Crystal structures of compounds 1-4 were solved by a single crystal X-ray diffraction method. 1: space group C2/c, a = 12.535(2), b = 16.0294(18), c = 7.6214(9) ?, β = 107.189(11)°, Z = 4, R = 0.029. 2: space group P21/c, a = 7.559(2), b = 13.1225(15), c = 13.927(4) ?, β = 97.14(3)°, Z = 2, R = 0.031. 3: space group P21/c, a = 7.606(3), b = 13.137(3), c = 14.026(5) ?, β = 97.14(3)°, Z = 2, R = 0.056. 4: space group P21/n, a = 7.9050(16), b = 7.7718(16), c = 18.233(4) ?, β = 97.45(3)°, Z = 4, R = 0.043. All solid state structures feature one-dimensional (BiI4)- anionic chains built of [BiI6] octahedra that share two opposite edges in such a fashion that two iodine atoms in cis-positions remain terminal. The calculated electronic structures and observed optical properties confirmed that compounds 1-4 are semiconductors with direct band gaps of 1.70-1.76 eV, which correspond to their intense red color. It was shown that the cations do not affect the optical properties, and the optical absorption is primarily associated with the charge transfer from the I 5p orbitals at the top of the valence band to the Bi 6p orbitals at the bottom of the conduction band. Based on their properties and facile synthesis, the title compounds are proposed as promising light-harvesting materials for all-solid solar cells.

Ultraviolet (UV) irradiation of HI-doped xenon matrix dissociates the precursor and leads to the formation and trapping of neutral atoms. After UV photolysis, annealing of the matrix mobilizes the hydrogen atoms at about 38 K. The mobilized hydrogen atoms react with I/Xe centers forming HXeI molecules in a diffusion controlled reaction. The formed molecules can be photolyzed with infrared (IR) irradiation at 2950-3800 cm-1 and quantitatively regenerated thermally. The formation of HXeI from neutral atoms is proved by the quantitative correlation between neutral iodine atoms and HXeI molecules in selective IR photodissociation and thermal regeneration experiments. Kinetic measurements show that the formation of HXeI from atoms is prevented by a potential barrier, which is estimated to be 700 cm-1 in magnitude. The potential barrier is proposed to originate from the avoided crossing between neutral H+Xe+I and ionic (HXe)++I- singlet surfaces. The dissociation energy D0 of HXeI with respect to the top of the potential barrier is estimated to be 2950 cm-1 and De about 4070 cm-1 in solid Xe. The weak IR photodissociation profile of HXeI around 3000 cm-1 is measured by irradiating the sample with tunable IR source and monitoring the changes in the fundamental region. The formation mechanism from neutral atoms is believed to be valid for other similar rare-gas compounds.

Thermal decomposition of cadmium thiourea coordination compounds was considered. Cadmium sulfide is the final product for all the compounds, whereas the composition of other products of the thermolysis substantially depends on the nature of the acido ligand or the outer-sphere anion. Thermal stability parameters of the coordination compounds under study and effective activation energies of their thermolysis were determined, and a mechanism of the thermolysis was proposed.

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The bimolecular rate constants for the reactions of ground state atomic nitrogen with hydrogen halides and deuterium iodide were measured by employing a pulse radiolysis-resonance absorption technique.As for the reactions of hydrogen iodide and deuterium iodide, the temperature dependence was also measured; it was found that the rate constants were well expressed by the following Arrhenius expressions: k(N+HI)=(3.6+/-0.6)E5 exp; k(N+DI)=(1.0+/-0.4) exp, in units of m3mol-1s-1.The preexponential factors for these reactions are much smaller than the semiempirically calculated ones.These small preexponential factors suggest that these reactions proceed non-adiabatically.The rate constants for hydrogen bromide and hydrogen chloride were found to be very small.

Hybrid lead halide perovskites have emerged as promising active materials for photovoltaic cells. Although superb efficiencies have been achieved, it is widely recognized that long-term stability is a key challenge intimately determining the future development of perovskite-based photovoltaic technology. Herein, we present reversible and irreversible photodecomposition reactions of methylammonium lead iodide (MAPbI3). Simulated sunlight irradiation and temperature (40-80 °C) corresponding to solar cell working conditions lead to three degradation pathways: (1) CH3NH2 + HI (identified as the reversible path), (2) NH3 + CH3I (the irreversible or detrimental path), and (3) a reversible Pb(0) + I2(g) photodecomposition reaction. If only the reversible reactions (1) and (3) take place and reaction (2) can be avoided, encapsulated MAPbI3 can be regenerated during the off-illumination timeframe. Therefore, to further improve operational stability in hybrid perovskite solar cells, detailed understanding of how to mitigate photodegradation and thermal degradation processes is necessary. First, encapsulation of the device is necessary not only to avoid contact of the perovskite with ambient air, but also to prevent leakage of volatile products released from the perovskite. Second, careful selection of the organic cations in the compositional formula of the perovskite is necessary to avoid irreversible reactions. Third, selective contacts must be as chemically inert as possible toward the volatile released products. Finally, hybrid halide perovskite materials are speculated to undergo a dynamic formation and decomposition process; this can gradually decrease the crystalline grain size of the perovskite with time; therefore, efforts to deposit highly crystalline perovskites with large crystal sizes may fail to increase the long-term stability of photovoltaic devices.

Herein, we report an efficient and practical hydroiodination of internal alkynes using HI generated ex situ from the readily available triethylsilane and I2. This system offers high regio- and stereoselectivity to afford (E)-vinyl iodides in good yields under mild conditions. Furthermore, the hydroiodination reaction shows high functional group tolerance toward alkyl, methoxy, halogen, trifluoromethyl, cyano, ester, halomethyl, acid-sensitive silyl ether, and acetal moieties.

Molecular iodine, an easy to handle solid, has been successfully employed as a catalyst in different organic transformations for more than 100 years. Despite being active even in very small amounts, the origin of this remarkable catalytic effect is still unknown. Both a halogen bond mechanism as well as hidden Br?nsted acid catalysis are frequently discussed as possible explanations. Our kinetic analyses reveal a reaction order of 1 in iodine, indicating that higher iodine species are not involved in the rate-limiting transition state. Our experimental investigations rule out hidden Br?nsted acid catalysis by partial decomposition of I2 to HI and suggest a halogen bond activation instead. Finally, molecular iodine turned out to be a similar if not superior catalyst for Michael additions compared with typical Lewis acids.

The "element effect" in nucleophilic aromatic substitution reactions (SNAr) is characterized by the leaving group order, L = F > NO2 > Cl ≈ Br > I, in activated aryl substrates. A different leaving group order is observed in the subs

Thermal decomposition of the energetic ionic liquids 1-methyl-4-amino-1,2, 4-triazolium iodide (Me4ATI), 1-methyl-4-amino-1,2,4-triazolium nitrate (Me4ATN), 1-amino-3-methyl-1,2,3-triazolium iodide (Me1ATI), and 1-amino-3-methyl-1,2,3-triazolium nitrate (Me1ATN) was studied by confined rapid thermolysis. Sub-milligram quantities of the compounds were subjected to decomposition under isothermal conditions achieved by initially heating the sample at rates of approximately 2000 K/s. The products formed by decomposition under the afore-mentioned conditions were sampled by rapid scan FTIR spectroscopy and time-of-flight mass spectrometry. Decomposition studies involving the iodide salts were carried out around 270-290.C, whereas the nitrate salts were subjected to 320-340.C. The amino group was found to be involved in the initiation reaction, forming copious quantities of ammonia from the iodide compounds and, N2O and H2 O from the nitrate compounds. The extent of decomposition of the triazole ring was minimal at the considered temperatures.

The reaction of the closo-dodecaborate anion with hydrogen halides in dichloroethane is studied. Regardless of the hydrogen halide used (HCl, HBr, HI), the chlorination process with the formation of monoand disubstituted products is the main in all cases. The substitution has a weakly pronounced stepwise character. The synthesized compounds are identified by IR spectroscopy, 11B NMR, and ESI mass spectrometry. The structure of a single crystal of the complex Ni(Bipy)3(B12H 10.668Cl1.332) ? 3CH2CN ? 0.464H 2O is determined by X-ray diffraction analysis. Nauka/Interperiodica 2007.

This application relates to the use of phosphonium-based ionic liquids as recyclable solvents for solution phase chemistry. The ionic liquids may be used, for example, as solvents for reactions involving Grignard reagents, hydridic reagents, metallic and non-metallic reducing agents, and strong bases, including nucleophilic carbenes and Wittig reagents. In one embodiment the invention may comprise homogeneous mixtures of strong bases/nucleophiles/reducing agents and tetrahydrocarbylphosphonium salt ionic liquids. The invention also relates to chemical processes that may proceed in either minimally flammable solvent, or a complete absence of flammable solvent, including systems containing strong reducing agents such as alkali and alkaline metals or metal and non-metal hydrides. Methods for generating anions and nucleophililic carbenes (imidazol-2-ylidenes) (and complexes derived from them) in phosphonium-based ionic liquids are also described. The invention demonstrates the feasibility of using phosphonium-based ionic liquids as a reliable reaction media for a wide variety of basic reagents. The problems associated with C-H activation in imidazolium-based ionic liquids by highly reactive bases are not observed for phosphonium-based ionic liquids.

Iodobenzoborirene is obtained photochemically (λ = 308 nm) from diiodophenylborane by elimination of HI in solid argon at 10 K. The Royal Society of Chemistry 2005.

Novel compounds of the formula I 1in which R1, R2, R2′, R2″, R3, R4, R5, R5′, R5″, R5′″, R5″″, X, Y, U, V and W are as defined in Patent claim 1, are inhibitors of coagulation factors Xa and VIIa and can be employed fr the treatment of thromboses, myocardilal infarction, arteriosclerosis, inflammation, apoplexia, angina pectoris, restenosis after angioplasty, claudicatio intermittens, tumours, tumour diseases and/or tumour metastases.

The study of the behavior of (137)Cs(131)I in the presence of MCl (M = NH4(1+), K(1+), Ag(1+), and Cu(1+)) in the water vapor-gas phase showed that CsI aerosols are localized in the MCl matrix owing to both agglomeration cocrystallization [(137)Cs(131)I-MCl systems (M = K(1+), Ag(1+), NH4(1+))] and agglomeration capture [(137)Cs(131)I-CuCl system]. The main advantage of the first process is formation of crystalline globules encapsulating radioiodine in their bulk, which prevents transformation of radioiodine into elemental iodine and methyl iodine.

I-atom atomic resonance absorption spectrometry has been used to measure thermal rate constants for the I+H2 → HI+H reaction between 1755 and 2605 K in reflected shock waves. Measured rate constants can then be expressed by k1=(3.92±

The thermodynamical data of ammonium neodymium iodides (NH4)3NdI6 and (NH4)2NdIs were derived by the determination of their decomposition equilibria by total pressure measurements. Moreover

Chemical quasi-equilibria represent the product composition of stable components at the outlet of a nonisothermal plasma chemical reactor under operating conditions of very high or vanishing electric power input. The properties of these quasi-equilibria in relation to the thermodynamic equilibrium are discussed first of all using an instructive kinetic model. The investigations show that for the formation of the quasiequilibria the existence of two time scales for the chemical conversions in the system is necessary. The quasi-equilibrium states are formed on a short time scale by fast relaxation and deactivation processes of unstable components. After that the system passes into the thermodynamic equilibrium for very long times. The transition from a chemical quasi-equilibrium state into the thermodynamic equilibrium was detected in the H2-I2-HI system experimentally, too. The analysis of a detailed microphysical model for this system shows that the transition into the thermodynamic equilibrium is caused by the increasing thermal production of unstable components (e.g. iodine atoms) at higher gas temperatures. Under these conditions the electronic production of atoms is only a small correction of the thermal degree of dissociation, and the thermodynamic equilibrium is the only stationary state for the system.

Rate constants for the reaction of H atoms with CF3I have been measured using the flash-photolysis/resonance fluorescence technique over 295-730K. The results are k=(6.7+/-0.3) E-11 exp[(-3.8+/-0.2) kJ mol**-1/RT] c m**3 molecule**-1 s**-1, where the uncertainties represent +/-1σ in the Arrhenius parameters. Error limits for k are +/-10%. The reaction is shown to be dominant pathway for consumption of CF3I in a stiochiometric methane/air flame.

Compounds of the formula I STR1 in which R1 and X have the meanings herein defined, their physiologically unobjectionable salts and/or solvates inhibit the binding of fibrinogen to the corresponding receptor and can be employed for the treatment of thromboses, osteoporosis, tumoral diseases, apoplexy, cardiac infarction, inflammations, arteriosclerosis and osteolytic disorders.

(NH4)3YI6 decomposes directly into YI3(s), NH3(g) and HI(g). In connection with the thermal decomposition of NH4I the decomposition-pressure-function is given and the enthalpy of formation and the standard entropy ofthe phases are derived.

New 4-substituted azetidinones having the formulae I and II: STR1 wherein X is oxygen, sulfur or a moiety of the formula NR6 where R1, R2, R3, R4, R5 and R6 are defined hereafter, which are intermediates for the preparation of carbapenem and carbacephem antibacterials and processes for producing such antibacterials through the utilization of an acid mediated ring closure reaction.

New 4-substituted azetidinones having the formulea I and II: STR1 with R1, R2, R3, R4, R5 and X defined hereafter, which are intermediates for the preparation of carbapenem and carbacephem antibacterials and processes for producing such antibacterials through the utilization of an acid mediated ring closure reaction.

Using a selected ion flow tube at 368 K, we have measured rate constants for ion-molecule reactions between I-, PO-, HSO4-, FSO3-, CF3SO3-, NO3-·HNO3, FSO3-·FSO3H, and H2SO4, FSO3H, CF3SO3H. Channels observed include proton transfer and clustering. These results allow free energies (enthalpies) of deprotonation (kJ/mol) to be estimated (within ±10 kJ/mol) as follows: HPO3, 1270 (1300); H2SO4, 1265 (1295); FSO3H, 1255 (1285); CF3SO3H, 1250 (1280). In two cases, electron affinities are estimated as follows: HSO4, 4.7 ± 0.2 eV. FSO3, 4.8 ± 0.2 eV. For the title acids, the gas-phase acidity order is discussed and is used to explain the differing acidity orders found for these acids in different solvents. The same data measure basicities for the conjugate bases, and these are related to nucleophilicity and leaving group ability. This study explores a region of the acidity scale where no acidities are established that would calibrate the scale. The scale is calibrated here using cluster ions whose free energy of protonation can be reliably estimated.

By using an appropriate coordinate system the arc length between two points on the geodesic reaction path is equal to the absolute difference between the function values (energies) belonging to the same points.This gives the possibility to avoid the tedious integration procedure necessary to get a measure of the position of the saddle point (or any other point) in the one-dimensional space of the reaction path.The method is illustrated by reaction coordinate values of transition states for a number of atom transfer reactions in comparison with those calculated by an independent method.Reaction coordinates also computed by using analytical functions are compared with those obtained by direct integration.

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The rate coefficient (k7) for the reaction of iodine atoms with HO2 radicals, I + HO2 -> HI + O2, has been measured directly with use of the discharge-flow/EPR technique, and the molecular-modulation/UV-absorption spectroscopy technique.Discharge-flow measurements were made under pseudo-first-order conditions with iodine atoms in large excess over HO2.Molecular-modulation measurements were made with iodine atoms in excess over HO2, but the I + HO2 raection was occuring in competition with the self-reaction of HO2.The value of k7 determined at 298 K by these complementary methods agree within the combined experimental errors and provide a value of (3.8+/-1.0)x10-13 cm3 molecule-1 s-1.Further measurements made over the temperature range 283-353 K with the molecular-modulation technique allow recommendation of the following expression: k7=(1.47+/-0.63) x 10-11 exp(-(1090+/-130)/T).The potential significance of this reaction as a sink for iodine in the troposphere and the other aspects of tropospheric iodine chemistry are considered with a simple model of the atmospheric boundary layer.

This disclosure describes novel substituted guanidinedicarbonyl derivatives which possess anxiolytic activity and are also useful as agents for the treatment of cognitive and related neural behavioral problems in mammals.

The gas-phase chemistry of Ni(1+) and the monoligated nickel cations NiCO(1+), NiPF3(1+), and NiC5H5(1+) with a series of aromatic compounds is reported here.The phenyl group is largely unreactive and does not appear to prohibit the metal ion from interacting with other parts of these molecules.For some phenyl compounds, C6H5X, no reaction is observed for Ni(1+).When Ni(1+) does react, products such as NiC6H4(1+) and NiC5H5(1+) are formed-depending on the chemical composition of the attached functional group (X).Ni+ reacts with benzyl compounds by insertion into the C6H5CH2-X bond, frequently followed by charge transfer to form C7H7(1+) as a product.The Ni(1+) ion is observed to decarbonylate aromatic carbonyl compounds.When a single ligand is attached to the Ni(1+), changes in the chemistry are observed.In many cases, the reactivity decreases as the size of ligand increases, suggesting the importance of steric interactions even for these monoligated species.There are some exceptions, where NiC5H5(1+) is most reactive, even thought the cyclopentadienyl ligand is the largest.It is suggested that some charge transfer may occur in NiC5H5(1+), resulting in increased positive charge on the metal, loading to increased reactivity.

Experiments have been undertaken at the UKAEA Atomic Energy Establishment Winfrith to study specific chemical effects in terms of the physicochemical behavior of fission product species at high temperatures. The chemical forms of fission product vapors released from simulant fuel mixtures have been determined by matrix isolation-infrared spectroscopy and quadrupole mass spectrometry. Experimental work on simultant fission products has included studies of cesium iodide, cesium hydroxide, tellurium, strontium oxide, and barium oxide, and their reactions with 304 stainless steel, Zircaloy, and boric acid.

This invention provides the neuromuscular blocking agents of formula (I): STR1 where B and C are each a group of formula (II) and are meta or para to one another: STR2 wherein D is CH2 CH2 or CH=CH (preferably trans); Y is alkyl of 1

The Mg-S-I water splitting cycle was demonstrated on a laboratory scale by constructing an apparatus for repeated operations of chemical reactions of the whole cycle and by the circulation of reactants through purely thermochemical proceses below 1000 deg C.Electric furnaces and quartz glass reactors were used.Sixteen times of cycle operations were performed in 16 h with production rates of 0.3 liter H2/h and 0.15 liter O2/h.

A new thermochemical cycle for hydrogen production is presented.It consists of (i) redox reaction of sulfur dioxide and iodine with magnesium oxide in an aquenous solution, (ii) hydrolysis of magnesium iodide, (iii) thermal decomposition of magnesium sulfate and (iv) thermal dissociation of hydrogen iodide.Key reaction (i) and (ii) were experimentally verified.

The procedure of Johnston and Parr for computing the potential energy and structure of a triatomic linear activated complex containing hydrogen as its central atom has been combined with the EyringPolanyi rate-constant expression to calculate rate constants at 1000° to 4000°K of gas-phase hydrogen-atom transfers for every possible reaction between the ground states of the atoms H, Li, Be, B, C, N, O, F, Na, Cl, Br, I, and any of the diatomic hydrogen compounds of these elements. The relation between activated complex theory and collision theory for reactions of this sort is examined in detail. The usual form of activated complex theory breaks down for reactions of low activation energy and high temperature, and the conditions for this failure in terms of bending vibrational amplitude are given. For these cases rate constants are evaluated by hard-sphere collision theory. Although calculated activation energy and other parameters differ from one reaction to another, these differences become unimportant at very high temperature. Almost all calculated rate constants have a value within a factor of 4 of the single value 2X10 13cc/mole/sec at 2500°K.