Bypassing the Multi-reference Character of Singlet Molecular Oxygen. Part 2: Ene-reaction

Theoretical calculations involving singlet molecular oxygen (O2(1g)) are challeng- ing due to their inherent multi-reference character. We have tested the quality of re- stricted and unrestricted DFT geometries obtained for the reaction between singlet oxy- gen and a series of alkenes (propene, 2-methylpropene, trans-butene, 2-methylbutene and 2,3-dimethylbutene) which are able to follow the ene-reaction. The electronic en- ergy of the obtained geometries are rened using 3 dierent methods which account for the multi-reference character of singlet oxygen. The results show that the mechanism for the ene-reaction is qualitatively dierent when either one or two allylic-hydrogen groups are available for the reaction. When one allylic-hydrogen group is available the UDFT calculations predict a stepwise addition forming a biradical intermediate, while, the RDFT calculations predict a concerted reaction where both hydrogen abstrac- tion and oxygen addition occur simultaneously. When two allylic-hydrogen groups are available for the reaction then UDFT and RDFT predict the same reaction mechanism, namely that the reaction occurs as a stepwise addition without a stable intermediate between the two transition states. The calculated rate constants are in reasonable agreement with experimental data, except for trans-butene where the calculated rate constant is three orders of magnitude lower than the experimental one. In conclusion we nd that the simple bypassing scheme tested in this paper is a robust approach for calculations of reaction involving singlet oxygen in the limit that the transition state processes low multi-reference character. 2

Detailed kinetics of tetrafluoroethene ozonolysis

The reaction mechanism was explored at the CCSD(T)/CBS//B3LYP/aug-cc-pVTZ level. Detailed kinetic analysis was firstly carried out using an ME/RRKM rate model with the inclusion of anharmonic and tunneling treatments. 1,3-Cycloaddition is found to be the rate-determining step. Calculated rate constants confirm the latest experimental data.

Theoretical study of the structure and dehydrogenation mechanism of sodium hydrazinidoborane

Alkali-metal hydrazinidoboranes have been recently investigated as a new stable high-capacity material for hydrogen storage, necessitating an exploration of the dehydrogenation mechanism for further developments in this field. Herein, we present a first systematic study of the structure and dehydrogenation mechanism of sodium hydrazinidoborane (NaHB) with three possible pathways considered: pathway A, corresponding to unimolecular dehydrogenation; pathway B, featuring dehydrogenation of the (NaHB)2 dimer via two different sub-pathways, and pathway C, corresponding to direct dehydrogenation (as compared to B). The calculated rate of the most probable dehydrogenation pathway (B, 3.28[Formula: see text]min[Formula: see text] is similar to that obtained experimentally (12.26[Formula: see text]min[Formula: see text], supporting the validity of our findings.

Fabrication of PANI/C-TiO2Composite Nanotube Arrays Electrode for Supercapacitor

Polyaniline/carbon doped TiO2composite nanotube arrays (PANI/C-TiO2NTAs) have been prepared successfully by electrodepositing PANI in C-TiO2NTAs which were prepared by directly annealing the as-anodized TiO2NTAs under Ar atmosphere. The organic residual in the TiO2NTAs during the process of anodization acts as carbon source and is carbonized in Ar atmosphere to manufacture the C-TiO2NTAs. The specific capacitance of the PANI/C-TiO2electrode is 120.8 mF cm−2at a current density of 0.1 mA cm−2and remains 104.3 mF cm−2at a current density of 2 mA cm−2with the calculated rate performance of 86.3%. After 5000 times of charge-discharge cycling at a current density of 0.2 mA cm−2, the specific capacitance retains 88.7% compared to the first cycle. All these outstanding performances of the as-prepared PANI/C-TiO2NTAs indicate it will be a promising electrode for supercapacitor.

On Exponential Flocking to the Virtual Leader in Network of Agents With Double-Integrator Dynamics

This paper considers flocking to the virtual leader in network of agents with double-integrator. A locally linear algorithm is employed which guarantees exponential flocking to the virtual leader. A lower bound for flocking rate is calculated which is independent of the initial conditions. Simulations are provided to validate the result and it is shown that the calculated rate is not over bound the actual convergence rate. The effect of coefficients of algorithm is investigated and it is shown that the similar results can be inferred from the calculated formula for the convergence rate.

Kinetics of iron(III) hydrolysis and precipitation in aqueous glycine solutions assessed by voltammetry

The kinetics of iron(III) hydrolysis and precipitation in aqueous glycine solutions were studied by cathodic voltammetry with a mercury drop electrode. The kinetics was controlled by changing ionic strength (I), pH and glycine concentration. Voltammetric measurements clearly showed formation and dissociation of a soluble Fe(III)–glycine complex, formation of iron(III) hydroxide and its precipitation. The rate constants of iron(III) hydroxide precipitation were assessed. The precipitation is first-order with respect to dissolved inorganic iron(III). The calculated rate constants of iron(III) precipitation varied from 0.18 × 10–5 s–1 (at 0.2 M total glycine, pH 7.30, I = 0.6 mol dm–3) to 2.22 × 10–3 s–1 (at 0.1 M total glycine, pH 7.30, I = 0.2 mol dm–3). At 0.5 M total glycine and I = 0.6 mol dm–3, the iron(III) precipitation was not observed.