Lif study of the I2+F → IF+I reaction: population of the v' = 0 level of IF

We have attempted to detect the v' =0 level in IF molecules produced by the reactive collision I₂+F → IF+I under crossed-beam conditions. The signal that we have observed is shown to be due to a background IF vapour. This is an important result as it settles a controversy concerning the energy disposal in this reaction.     

Rate of the reaction I2 + F2 → products

The rate coefficient, k1, for the reaction I2+F2k1→ products has been measured at room temperature to be k1 = (1.9 = 0.4) × 10?15 cm3/molecule s. The macroscopic rate is compared to microscopic cross-section data obtained from molecular beam experiments and is found to be consistent with the bimolecular reaction I2 + F2→ I2F + F.DG|National Research Council/Resident Research Associate.     

Mechanism and kinetics of the reaction of F with trivalent phosphorus iodide using electron spin resonance detection

The reaction of iodobistrifluoromethylphosphine, P(CF₃)₂I, with atomic fluorine was studied by fast-flow ESR methods. The initial stage of the reaction is the abstraction of I by F, to form IF with a bimolecular rate constant of (1.0 ± 0.3) × 10¹⁴ cm³ mol^?1 s^?1 at 297 K. In the presence of excess F, stepwise addition to the phosphorous occurs. In the presence of excess P(CF₃)₂I, the reaction P(CF₃)₂ + IF → P (CF₃)₂F + I appears to take place. This reaction rate is slow relative to P(CF₃)₂ + F → P(CF₃)₂F.     

Reactions of fluorine atoms with iodides studied by crossed beam laser-induced fluorescence

The reactions of F atoms with C₂H₅I, C₂F₅I, and n-C₃H₅I were studied by the crossed beam laser-induced fluorescence techniques within the 570–620 nm wavelength region. The vibrational and rotational excitation spectra of the reaction product IF were measured. The relative vibrational population densities of v = 3,4, and 5 vibrational levels, and some of the relative detailed vibrational rate constants, the rotational temperatures, and the mean fractions of rotational energy in individual vibrational states of the reaction product IF were obtained. The reaction mechanism was discussed.     

Bis(μ-2-cyano­pyridine-N:N′)­bis­[(2-cyano­pyridine-N)silver(I)] bis­(tetra­fluoro­borate): an anion-linked molecular ladder

In the title compound, [Ag₂(C₆H₄N₂)₄](BF₄)₂, the Ag^I cations adopt distorted trigonal-planar coordination geometries. The Ag^I centres are linked via two bridging 2-cyano­pyridine ligands to give a centrosymmetric dinuclear complex in which the Ag^I coordination environment is completed by monodentate non-bridging 2-cyano­pyridine ligands. Bridging Ag⋯F(BF₂)F⋯Ag interactions link the dinuclear cations into molecular ladders.     

Cyclopropanation of alkenes with CH2I2/Et3Al by the phase-vanishing method based on fluorous phase screen

Phase-vanishing (PV) method using perfluorohexanes as a screen phase was applied to cyclopropanation reactions with CH₂I₂/Et₂Zn and CH₂I₂/Et₃Al. When Et₃Al was used as a carbenoid generator, the reaction proceeded smoothly and desired cyclopropane derivatives were obtained in high yield. The PV cyclopropanation took 2 or 3 days to complete, however, reduction of reaction time by a factor of 2-3 was also achieved by vigorous stirring after the bottom CH₂I₂ layer disappeared.     

Der chemische Transport von FeP2 und FeP4 mit lod

Chemical Transport of FeP₂ and FeP₄ with Iodine Experiments on the chemical transport of FeP₂ and FeP₄ with iodine are discussed, considering the gaseous molecules I₁, I₂, FeI₂, Fe₂I₄, FeI₃, Fe₂I₆, PI₃, P₂I₄, P₄, P₂, and P. Thermodynamic calculations give δH°(298) = 56.322 kcal and ΔS°(298) = 39.5 cal/K for the reaction FeP_2,f + I₂ = FeI₂ + 0.5 P₄ and δG°(923) = 35.8 kcal for the reaction FeP_4,f + I₂ = FeI₂ + P₄.     

Photodissociation of CH2I2 and Subsequent Electron Transfer in Solution

We studied photoinduced reactions of diiodomethane (CH₂I₂) upon excitation at 268 nm in acetonitrile and hexane by subpicosecond–nanosecond transient absorption spectroscopy. The transient spectra involve two absorption bands centered at around 400 (intense) and 540 nm (weak). The transients probed over the range 340–740 nm show common time profiles consisting of a fast rise (<200 fs), a fast decay (≈500 fs), and a slow rise. The two fast components were independent of solute concentration, whereas the slow rise became faster (7–50 ps) when the concentration in both solutions was increased. We assigned the fast components to the generation of a CH₂I radical by direct dissociation of the photoexcited CH₂I₂ and its disappearance by subsequent primary geminate recombination. The concentration‐dependent slow rise produced the absorption bands centered at 400 and 540 nm. The former consists of different time‐dependent bands at 385 and 430 nm. The band near 430 nm grew first and was assigned to a charge‐transfer (CT) complex, CH₂I₂^δ+???I^δ?, formed by a photofragment I atom and the solute CH₂I₂ molecule. The CT complex is followed by full electron transfer, which then develops the band of the ion pair CH₂I₂⁺???I^? at 385 nm on the picosecond timescale. On the nanosecond scale, I₃^? was generated after decay of the ion pair. The reaction scheme and kinetics were elucidated by the time‐resolved absorption spectra and the reaction rate equations. We ascribed concentration‐dependent dynamics to the CT‐complex formation in pre‐existing aggregates of CH₂I₂ and analyzed how solutes are aggregated at a given bulk concentration by evaluating a relative local concentration. Whereas the local concentration in hexane monotonically increased as a function of the bulk concentration, that in acetonitrile gradually became saturated. The number of CH₂I₂ molecules that can participate in CT‐complex formation has an upper limit that depends on the size of aggregation or spatial restriction in the neighboring region of the initially photoexcited CH₂I₂. Such conditions were achieved at lower concentrations in acetonitrile than in hexane.     

Über die Existenz Polymerer Jodylionen (JO2+)x in den Verbindungen J2O5· n SO3 (n = 1,2,3) und JO2SO3F

On the Existence of Polymeric Iodyl Ions (IO₂⁺)_x in the Compounds I₂O₅ · n SO₃ (n = 1, 2, 3) and IO₂SO₃F The Raman spectra of I₂O₅ · SO₃, I₂O₅ · 2 SO₃ and I₂O₅ · 3 SO₃ are reported and interpreted together with the known spectrum of IO₂SO₃F. In first approximation the structure of the compounds is described by the existence of polymeric iodyl ions (IO₂⁺)_x. The bonds between cation and anion are not purely ionic but are in part covalent. These are formulated as coordinative bonds.     

The NO- and NO2-catalyzed decomposition of I2 in shock waves

Measurements of the NO-catalyzed dissociation of I₂ in Ar in incident shock waves were carried out in the temperature range of 700°-1520°K and at total concentrations of 5 × 10^?6-6 × 10^?5 mol/cm³, using ultraviolet-visible absorption techniques to monitor the disappearance of I₂. It was shown that the main reaction responsible for the disappearance under these conditions is I₂ + NO → INO + I, for which a rate coefficient of (2.9 ± 0.5) × 10¹³ exp[-(18.0 ± 0.6 kcal/mol)/RT] cm²/mol·sec was determined. The INO formed dissociates rapidly in a subsequent reaction. The reaction, therefore, constitutes a “chemical model” for a “thermal collisional release mechanism.” Preliminary measurements of the rate coefficient for I₂ + NO₂ → INO₂ + I are also presented. Combined with information on the reverse reactions obtained in earlier room temperature experiments, these results lead to accurate values of ΔH°_f for INO and INO₂ equal to 29.7 ± 0.5 and 15.9 ± 1 kcal/mol, respectively.     

Origin of InI emission in laser studies of the crossed beam reaction In+I2

When a beam of In is cross fired at a beam of I₂ and the intersection is irradiated by various cw laser sources, InI emission is observed. The origin of this emission is shown to be laser-induced fluorescence (LIF) from the ground state indium monoiodide product of the reaction In + I₂ → InI + I, rather than laser-induced chemiluminescence (LIC) through the excitation of the I₂ reagent in the reaction In + I₂³ → InI* + I. An upper bound on the cross section for the later process is estimated to be ?2.5 × 10^?16 cm². The LIF excitation spectrum reveals a strong inversion in the InI vibrational population distribution, with the fraction of the total excess energy of reaction in vibration exceeding 0.5. Preliminary results for the Tl + I₂ reaction system show the same LIF m     

Ba3P3I2 und Ba5P5I3: Stufenweise Oxidation von Bariumphosphid mit Iod

Ba₃P₃I₂ and Ba₅P₅I₃: Stepwise Oxidation of Barium Phosphide with Iodine The novel compounds Ba₃P₃I₂ and Ba₅P₅I₃ were obtained by the reaction of barium phosphide with iodine. The air and moisture sensitive compounds crystallize in new structure types: Ba₃P₃I₂ (oP32; Pnma; a = 1719.5(4) pm; b = 462.4(2) pm; c = 1427.2(4) pm; Z = 4; R(F)_N′ = 0.067 (N′(hkl) = 2667), Ba₅P₅I₃ (mC52; C2/m; a = 4266.4(13) pm; b = 456.3(2) pm; c = 943.1(3) pm; ß = 92.20(3)°; Z = 4; R(F)_N′ = 0.040 (N′(hkl) = 3909). Both can be described as double salts of a hypothetic Zintl Phase ('Ba₂P₃' or 'Ba₇P₁₀') and a halide (BaI₂). Characteristic structural features are P₃ and P₄ chains, corresponding to Ba₃[P₃]I₂ and Ba₁₀[P₃]₂[P₄]I₆, respectively. The bonding characteristics will be interpreted on the basis of the structure and the physical properties.     

Isomerization of 1,2-diiodoethylene in a laser-induced chemical reaction of I2 + C2H2

A laser-induced chemical reaction of I₂ + C₂H₂ has been studied and the formation of cis and tians isomers of 1,2-diiodoethylene has been observed. The ratio of the two isomers of 1,2-diodoethylene changes markedly upon changing the laser wavelengths of excitation of the I₂ molecule     

Oscillatory continuum emission from the F(0u+) ion-pair state of I2

Oscillatory continuum emission, in the region 250–270 nm, from the second 0_u⁺ ion-pair (F) state of I₂ has been observed following single-photon excitation of I₂ at 169 nm, using synchrotron radiation.     

Formation and Crystal Structure of the Salt (IC(PPh3)2)2I[I3]·(I2)2 with a new Polyiodide Chain

The reaction of the carbodiphosphorane Ph₃P=C=PPh₃ ( 1 ) with MeI in the presence of iodine gives the oxidation product (IC(PPh₃)₂)₂I[I₃]·(I₂)₂ ( 2 ). In the solid state dimeric units linked by indefinite ···I^?···I₂···I₃^?···I₂···I^?··· chains are found. An additional I···I contact between the cation and the I₂ molecule is formed, amounting to 359.23(5) pm. 2 crystallizes in the monoclinic space group P2/c, with the unit cell dimensions a = 2053.9(1), b = 1011.4(1), c = 1889.8(1) pm; β = 105.21(1)° and Z = 4.     

Self-supported FexNi1-xMoO4 with synergistic morphology and composition for efficient overall water splitting at large current density

Developing the high activity, low cost and robust large-current-density-based electrocatalysts is of great significance for the industrial electrolytic water splitting. However, the current range of most reported materials is small, which makes it difficult for them to play their roles in practical applications. Here, a self-supported amorphous Fe_xNi_1-xMoO₄/IF treated with ammonium fluoride (AF_0.1-FNMO/IF) is synthesized by one-step hydrothermal method. With the help of NH₄F, AF_0.1-FNMO/IF exhibits a vertically cross-linked nanosheet with spherical structure. Electrochemical measurement shows that AF_0.1-FNMO/IF affords a large current density ordeal and only need low overpotentials of 289 and 345 mV to reach a current response of 500 mA/cm² for oxygen evolution reaction and hydrogen evolution reaction, respectively, together with long-time stability (both at 500, 1000 and 2000 mA/cm²) in 1.0 mol/L KOH solution. Using it as bifunctional catalyst for overall water splitting, the current densities of 100, 500, 1000 and 1500 mA/cm² are achieved at a cell voltage of 1.71, 1.88, 1.94 and 1.97 V with excellent durability, which is much better than that of most published electrodes. The work provides valuable insight for designing higher activity nickel iron-based molybdate catalysts with large current density.     

Trapping a Silicon(I) Radical with Carbenes: A Cationic cAAC–Silicon(I) Radical and an NHC–Parent‐Silyliumylidene Cation

The trapping of a silicon(I) radical with N‐heterocyclic carbenes is described. The reaction of the cyclic (alkyl)(amino) carbene [cAAC_Me] (cAAC_Me=:C(CMe₂)₂(CH₂)NAr, Ar=2,6‐i Pr₂C₆H₃) with H₂SiI₂ in a 3:1 molar ratio in DME afforded a mixture of the separated ion pair [(cAAC_Me)₂Si:^.]⁺I⁻ ( 1 ), which features a cationic cAAC–silicon(I) radical, and [cAAC_Me−H]⁺I⁻. In addition, the reaction of the NHC–iodosilicon(I) dimer [I_Ar(I)Si:]₂ (I_Ar=:C{N(Ar)CH}₂) with 4 equiv of I_Me (:C{N(Me)CMe}₂), which proceeded through the formation of a silicon(I) radical intermediate, afforded [(I_Me)₂SiH]⁺I⁻ ( 2 ) comprising the first NHC–parent‐silyliumylidene cation. Its further reaction with fluorobenzene afforded the C_Ar−H bond activation product [1‐F‐2‐I_Me‐C₆H₄]⁺I⁻ ( 3 ). The isolation of 2 and 3 confirmed the reaction mechanism for the formation of 1 . Compounds 1 – 3 were analyzed by EPR and NMR spectroscopy, DFT calculations, and X‐ray crystallography.     

Luminescent [Cu8I8L6] wheel and [Cu2I2L3] cage assembled from CuI and 3,6-bis(diphenylphosphino)pyridazine

The reaction of CuI and 3,6-bis(diphenylphosphino)pyridazine (dppz) in MeCN leads to the wheel-shaped complex [Cu₈I₈(dppz)₆], assembled from four [Cu₂I₂] units and six dppz ligands. This complex exhibits thermochromic luminescence with emission colors ranging from red (300 K) to deep red (77 K). When carried out in the presence of PPh₃, the reaction of CuI with dppz gives a non-emissive cage-like complex [Cu₂I₂(dppz)₃], in which two CuI units are P,P′-bridged by three dppz ligands.     

Untersuchungen an Polyhalogeniden. XXII [1]. Dimethyldiphenylammoniumpolyiodide (Me2Ph2N)In mit n = 3, 13/3, 6, 8: Darstellung und strukturelle Charakterisierung eines Triiodids (Me2Ph2N)I3, Tridecaiodids (Me2Ph2N)3I13, Dodecaiodids (Me2Ph2N)2I12 und Hexadecaiodids (Me2Ph2N)2I16

Studies of Polyhalides. 22. On Dimethyldiphenylammoniumpolyiodides (Me₂Ph₂N)I_n with n = 3, 13/3, 6, and 8: Preparation and Crystal Structures of a Triiodide (Me₂Ph₂N)I₃, Tridecaiodide (Me₂Ph₂N)₃I₁₃, Dodecaiodide (Me₂Ph₂N)₂I₁₂, and Hexadecaiodide (Me₂Ph₂N)₂I₁₆ The new compounds [(CH₃)₂(C₆H₅)₂N]I₃, [(CH₃)₂(C₆H₅)₂N]₃I₁₃, [(CH₃)₂(C₆H₅)₂N]₂I₁₂ and [(CH₃)₂(C₆H₅)₂N]₂I₁₆ have been prepared by the reaction of dimethyldiphenylammonium iodide [(CH₃)₂(C₆H₅)₂N]I with iodine I₂ in ethanol. Their crystal structures have been determined by single crystal X-ray diffraction methods. The structure of the triiodide may be described as a layerlike packing of pairs of nearly linear symmetric anions and tetraedral cations. The tridecaiodide forms zig-zag chains of iodide ions and iodine molecules with the iodide ion also weakly coordinated by two pentaiodide groups. The dodecaiodide is built from two pentaiodide-groups, which are bridged by an iodine molecule and connected with secondary bonds forming double chains. The hexadecaiodide ion forms layers built up from two heptaiodide groups and one iodine molecule. Thus the dimethyldiphenylammonium cation stabilizes a unique series of polyiodides of extraordinary composition and structure.     

F~2, F与I~2的化学发光反应

在流动余辉实验装置上,研究了F~2,F与I~2的化学发光反应。首次在F+I~2反应体系中观察到较强的IF(B→X)发射光谱,采用简单碰撞理论对IF(B)的振动驰豫进行估算后,得到了其振动布居,发现与F~2+I~2反应体系有明显的不同,从而推测这两个反应的激发态产物IF(B)是由不同的反应通道形成的。前者由初级反应产物I~2F与F原子进一步作用产生,而后者则由激发态的I(^2p~1~/~2)与基态的F(^2p~3~/~2)碰撞复合产生。