Ranges of light ions in materials with different densities

The ranges of He, Li, Be, B, and C ions in gases and NIKFI-Ya2 nuclear photoemulsion are considered. The general features of the range variations as functions of the energy and ion nuclear charges are discussed. The results of calculations are compared with experimental data and the data of calculations using the SRIM-2013 program.     

How can the metal affect the proton transfer to the dihydrides [{P(CH2CH2PPh2)3}MH2] (M = Fe,Ru, Os)? A low-temperature electronic spectroscopy study

According to low-temperature UV-Vis spectroscopy data, the two-step protonation of iron subgroup metal hydrides [{P(CH₂CH₂PPh₂)₃}MH₂] (M = Fe, Ru, Os) with p-nitrophenol includes the formation of ion pairs stabilized by a hydrogen bond between the cationic dihydrogen complex and the phenolate anion. The trend of the extent of proton transfer appeared to be aperiodic, FeI OsI < RuI, in contrast to the previously obtained sequence of the proton-acceptor capacity of the hydride ligand, which increases down the group.     

The character of the response of ZnO and SnO<Subscript>2</Subscript> sensors modified with porphyrins to volatile organic compounds

The influence of the modification of the surface of ZnO and SnO₂ sensors with 5,10,15,20-tetraphenylporphyrin on the parameters of sensor response to high-volatility organic substances was analyzed. The organic substances used were ethanol, acetone, and benzene. The sensor response was characterized by specific sensitivity γ determined as the ratio between a change in the resistance of the sensitive sensor layer and the volume concentration of high-volatility organic compounds introduced into the system. The modification of the sensors with tetraphenylporphyrin caused changes in sensor response, including a change in the sign of the γ parameter, which was of importance for creating “electronic nose” sensor systems.     

Method for calculating the nonequilibrium characteristics of light ions passing through thin organic films

A method is proposed for calculating the charge fractions, mean charges, and dispersion of the charge distribution in ion beams passing through thin organic films under nonequilibrium conditions. Calculations are performed for N ions travelling at different velocities (from 8 × 10⁸ to 12 × 10⁸ cm/s) in celluloid. The energy loss is estimated depending on the initial charge states and velocities of the incident ions.     

Nonequilibrium charge states of light ions penetrating through carbon films

The formation of helium, carbon, and nitrogen ion charge equilibrium upon their penetration through thin carbon films is examined. The ions under consideration have different initial charges and energies ranging from 0.3 to 3 MeV/nucleon. A semiempirical formula based on measured data is proposed for calculating the dependence of the mean nonequilibrium ion charge on the target thickness and estimating the carbon target thickness corresponding to the achievement of an equilibrium charge state.     

Coordination and organometallic chemistry of relevance to the rhodium-based catalyst for ethylene hydroamination

The RhCl(3)·3H(2)O/PPh(3)/nBu(4)PI catalytic system for the hydroamination of ethylene by aniline is shown to be thermally stable by a recycle experiment and by a kinetic profile study. The hypothesis of the reduction under catalytic conditions to a Rh(I) species is supported by the observation of a high catalytic activity for complex [RhI(PPh(3))(2)](2). New solution equilibrium studies on [RhX(PPh(3))(2)](2) (X = Cl, I) in the presence of ligands of relevance to the catalytic reaction (PPh(3), C(2)H(4), PhNH(2), X(-), and the model Et(2)NH amine) are reported. Complex [RhCl(PPh(3))(2)](2) shows broadening of the (31)P NMR signal upon addition of PhNH(2), indicating rapid equilibrium with a less thermodynamically stable adduct. The reaction with Et(2)NH gives extensive conversion into cis-RhCl(PPh(3))(2)(NHEt(2)), which is however in equilibrium with the starting material and free Et(2)NH. Excess NHEt(2) yields a H-bonded adduct cis-RhCl(PPh(3))(2)(Et(2)NH)···NHEt(2), in equilibrium with the precursors, as shown by IR spectroscopy. The iodide analogue [RhI(PPh(3))(2)](2) shows less pronounced reactions (no change with PhNH(2), less extensive addition of Et(2)NH with formation of cis-RhI(PPh(3))(2)(NHEt(2)), less extensive reaction of the latter with additional Et(2)NH to yield cis-RhI(PPh(3))(2)(Et(2)NH)···NHEt(2). The two [RhX(PPh(3))(2)](2) compounds do not show any evidence for addition of the corresponding X(-) to yield a putative [RhX(2)(PPh(3))(2)](-) adduct. The product of C(2)H(4) addition to [RhI(PPh(3))(2)](2), trans-RhI(PPh(3))(2)(C(2)H(4)), has been characterized in solution. Treatment of the RhCl(3)·3H(2)O/PPh(3)/nBu(4)PI/PhNH(2) mixture under catalytic conditions yields mostly [RhCl(PPh(3))(2)](2), and no significant halide exchange, demonstrating that the promoting effect of iodide must take place at the level of high energy catalytic intermediates. The equilibria have also been investigated at the computational level by DFT with treatment at the full QM level including solvation effects. The calculations confirm that the bridge splitting reaction is slightly less favorable for the iodido derivative. Overall, the study confirms the active role of rhodium(I) species in ethylene hydroamination catalyzed by RhCl(3)·3H(2)O/PPh(3)/nBu(4)PI and suggest that the catalyst resting state is [RhCl(PPh(3))(2)](2) or its C(2)H(4) adduct, RhCl(PPh(3))(2)(C(2)H(4)), under high ethylene pressure.     

Remarkable Structural and Electronic Features of the Complex Formed by Trimeric Copper Pyrazolate with Pentaphosphaferrocene

According to spectroscopic (NMR, IR, UV/Vis) study, the interaction of pentaphosphaferrocene [Cp*Fe(η⁵‐P₅)] with trimeric copper pyrazolate [(Cu{3,5‐(CF₃)₂Pz})₃] yields a new compound that is astonishingly stable in solution. Single‐crystal X‐ray analysis reveals unprecedented structural changes in the interacting molecules and the unique type of coordination [Cp*Fe(μ₃‐η⁵:η²,η²‐P₅){Cu(3,5‐(CF₃)₂Pz)}₃]. As a result of the 90° macrocycle folding, the copper atoms are able to behave both as a Lewis acid and as a Lewis base in the interaction with the cyclo‐P₅ ligand.     

Porphyrin photosensitizers solubilized with pluronics in the oxidation of tryptophan

It was shown that water-insoluble porphyrins solubilized with pluronics (ternary block copolymers of ethylene oxide and propylene oxide) efficiently transfer photoexcitation energy to molecular oxygen dissolved in aqueous media to excite it into the singlet state, which is active in oxidizing organic substrates. It was established that the degree of solubilization of porphyrin photosensitizers (PPSs) γ defined as the proportion of PPS molecules passed into the aqueous phase in the dissolution of formed films depends on a single parameter, the initial ratio between the porphyrin and pluronic molar concentrations q. γ = γ(q) dependences for the solubilization of dissimilar water-insoluble porphyrins were analyzed. It was shown that the behavior of all the obtained γ = γ(q) dependences is changed at a characteristic value q _max: when q ? q _max, γ ～ 1, and, when q ≥ ?q_max, the degree of solubilization decreases. It was concluded that solubilized porphyrins are efficient photosensitizers in the oxidation of organic substrates (tryptophan).     

Analysis of the relationship between the electron-capture and electron-loss cross sections for carbon ions

The electron-loss cross sections σ _{i, i + 1} and the electron-capture cross sections σ _{i, i ? 1} for carbon ions with energies of 35–330 keV/nucleon in hydrogen and neon are determined from experimental data. It is demonstrated that, for particle energies which satisfy the condition σ _{i, i + 1} = σ _{i, i ? 1} or σ _{i, i ? 1} = σ _{i ? 1, i} , the average equilibrium ion charge can be evaluated without solving the system of differential equations for charge exchange. The dependence of the average equilibrium ion charge on the ion energy is investigated for carbon ions.     

Energy loss of light ions with allowance for the presence of metastable particles in the ion beam

The change in the average ion charge due to the presence of particles in metastable states in beams of helium-like ions has been studied. The charge distributions and average charges have been calculated for ions with nuclear charges Z = 3?7 and a velocity of 3.65 au in nitrogen. The previously obtained data on the cross sections of loss and capture of electrons by metastable ions and ions in the ground state were used in the calculations. It is shown that the presence of metastable particles in ion beams leads to an increase in the average charge and energy loss for all considered ions.