Theoretical study of the mechanism for C-H bond activation in spin-forbidden reaction between Ti<Superscript>+</Superscript> and C<Subscript>2</Subscript>H<Subscript>4</Subscript>

The mechanism of the spin-forbidden reaction Ti⁺(⁴F, 3d²4s¹) + C₂H₄→TiC₂H₂ ⁺ (²A₂) + H₂ on both doublet and quartet potential energy surfaces has been investigated at the B3LYP level of theory. Crossing points between the potential energy surfaces and the possible spin inversion process are discussed by means of spin-orbit coupling (SOC) calculations. The strength of the SOC between the low-lying quartet state and the doublet state is 59.3 cm⁻¹ in the intermediate complex IM1-⁴B₂. Thus, the changes of its spin multiplicity may occur from the quartet to the doublet surface to form IM1-²A₁, leading to a sig-nificant decrease in the barrier height on the quartet PES. After the insertion intermediate IM2, two distinct reaction paths on the doublet PES have been found, i.e., a stepwise path and a concerted path. The latter is found to be the lowest energy path on the doublet PES to exothermic TiC₂H₂ ⁺(²A₂) + H₂ products, with the active barrier of 4.52 kcal/mol. In other words, this reaction proceeds in the following way: Ti⁺+C₂H₄→⁴IC→IM1-⁴B₂→^4,2ISC→IM1-²A₁→[²TS_ins]→IM2→[²TS_MCTS]→IM5→TiC₂H₂ ⁺(²A₂)+H₂. Supported by ‘Qinglan’ Talent Engineering Funds by Tianshui Normal University.     

Computational study on the reaction mechanism of the gas-phase atom-negative ion of S?+?NO2 ?: comparative study of mechanism with S?+?O3 reaction as isoelectronic and isostructure systems

The reaction mechanism of sulfur vapor (S) with nitrite ion (NO₂ ⁻) has been investigated theoretically on the triplet and singlet potential energy surfaces (PESs). All stationary points for the title reaction have been optimized at the B3LYP/6-311+G(3df) level. The energetic data have been obtained at the CCSD(T)//B3LYP level employing the 6-311+G(3df) basis set. Five stable collision complexes, ³IN1 (S–ONO⁻), ³IN2 (cyclic SONO⁻), ¹IN1 (cis S–ONO⁻), ¹IN2 (S–NO₂ ⁻), and ¹IN3 (trans S–ONO⁻), have been considered on the triplet and singlet PESs through barrier-less and exothermic processes. By starting from these complexes, a simple mechanism has been obtained on the triplet PES while a complex mechanism has been considered on the singlet PES. The calculated results show that there are no favorable paths for the reaction of S with NO₂ ⁻ on the singlet PES. Therefore, the S + NO₂ ⁻ reaction proceeds only on the triplet PES to produce ³SO + ³NO⁻ as main products. The results from the comparative study of S + NO₂ ⁻ reaction mechanism with S + O₃ (as isoelectronic and isostructure reactions) on the singlet PES show similarities in the overall trend of reaction mechanism and atom connectivity and differences in the stability of intermediates and the energy barriers of transition states.     

The time-resolved LMR method as used to measure elementary reaction rates of CI atoms and SiH3 radicals in pulse photolysis of S2Cl2 in the presence of SiH4

The time-resolved laser magnetic resonance (LMR) method has been applied to kinetic measurements for the first time. An intracavity spectrometer based on a CO₂ laser with resonant modulation of the magnetic field and with phase-sensitive detection of the signal has been used. Kinetic curves of generation and disappearance of CI atoms and SiH₃ radicals were obtained in the pulse photolysis of a mixture of S₂Cl₂ + SiH₄ under the fourth harmonic of a Nd laser (265 nm, 0.5 mJ, 12.5 Hz) at a total pressure of 520–980 Pa (he as diluent) and a temperature of 326 K. The reagent concentrations were: [S₂Cl₂ = (2.0?10.2)×10¹⁴ cm^?3, [SiH₄ = (2.4?17.4)×10¹³ cm^?3. To remove the transition saturation, 5.3×10¹⁵ cm^?3 CCl₄ was introduced into the reactor. The fraction of dissociated S₂Cl₂ was 1‰ Rate constants of the reactions (I) Cl+S₂Cl₂ → products, (II) Cl+SiH₄ → HCl+SiH₃ and a preliminary rate constant of the reaction (III) SiH₃ + S₂Cl₂ → products were obtained: k₁ ≤ (4.3±1.2)×10^?12 cm³/s, k₂ = (2.3±0.5)×10^?10 cm³/s, k₃ = (2.4±0.5)×10^?11 cm³/s. At a signal-to-noise ratio of 1:1, 1000 pulses and a 12 cm long detection zone the sensitivity to Cl atoms and to SiH₃ radicals was 4×10¹⁰ cm^?3 and = 10¹¹ cm^?3, respectively. The time resolution of the method was 4 μs. The method is shown to be promising for kinetic investigations and experiments on fast processes.     

Isopiestic Determination of the Osmotic Coefficients and Pitzer Model Representation for the Li<Subscript>2</Subscript>B<Subscript>4</Subscript>O<Subscript>7</Subscript>+LiCl + H<Subscript>2</Subscript>O System at <Emphasis Type="Italic">T</Emphasis>=298.15 K

Isopiestic molalities and water activities have been measured for the Li₂B₄O₇+LiCl + H₂O system at T=298.15 K using an improved isopiestic apparatus. Two types of osmotic coefficients, φ _S and φ _E, were determined, where φ _S is based on the stoichiometric molalities of the solute Li₂B₄O₇(aq) and φ _E is based on equilibrium molalities calculated by consideration of the equilibrium speciation of Li₂B₄O₇ to partially form H₃BO₃, B(OH)₄⁻ and B₃O₃(OH)₄⁻. The stoichiometric equilibrium constant K _m for the aqueous speciation reaction was estimated. Two representations of the osmotic coefficients of Li₂B₄O₇ + LiCl + H₂O were made with Pitzer’s ion-interaction model. Model (1) involved representing the φ _S values with six parameters based on considering the ionic interactions between Li⁺, Cl⁻, and B₄O₇²⁻; and model (2) involved representing the φ _E values based on the calculated equilibrium speciation. Reasonable agreements were obtained between the experimental osmotic coefficient data and those calculated using the above models, with standard deviations of 0.075 and 0.0229, respectively, for these two models. The thermodynamic osmotic coefficients for the complex system containing polymeric boron anions and lithium cation was modelled and explained by use of Pitzer’s ion-interaction model, with minor modifications in combination with speciation reaction equilibria.     

单分子水对H_2O_2+Cl气相反应影响的理论研究

在aug-cc-pVTZ基组下采用CCSD(T)和B3LYP方法,研究了H2O2+Cl反应,并考虑在大气中单个水分子对该反应的影响.结果表明,H2O2+Cl反应只存在一条生成产物为HO2+HCl的通道,其表观活化能为10.21kJ·mol-1.加入一分子水后,H2O2+Cl反应的产物并没有发生改变,但是所得势能面却比裸反应复杂得多,经历了RW1、RW2和RW3三条通道.水分子在通道RW1和RW2中对产物生成能垒的降低起显著的负催化作用,而在通道RW3中则起明显的正催化作用.利用经典过渡态理论(TST)并结合Wigner矫正模型计算了216.7-298.2 K温度范围内标题反应的速率常数.结果显示,298.2 K时通道R1的速率常数为1.60×10-13cm3·molecule-1·s-1,与所测实验值非常接近.此外,尽管通道RW3的速率常数kRW3比对应裸反应的速率常数kR1大了46.6-131倍,但该通道的有效速率常数k'RW3却比kR1小了10-14个数量级,表明在实际大气环境中水分子对H2O2+Cl反应几乎没有影响.     

Osmotic Coefficients of the Li<Subscript>2</Subscript>B<Subscript>4</Subscript>O<Subscript>7</Subscript>+LiCl + H<Subscript>2</Subscript>O System at <Emphasis Type="Italic">T</Emphasis>=273.15 K

Osmotic coefficients and water activities for the Li₂B₄O₇+LiCl+H₂O system have been measured at T=273.15 K by the isopiestic method, using an improved apparatus. Two types of osmotic coefficients, φ _S and φ _E, were determined. φ _S is based on the stoichiometric molalities of the solute Li₂B₄O₇(aq), and φ _E is based on equilibrium molalities from consideration of the equilibrium speciation into H₃BO₃,B(OH)₄⁻ and B₃O₃(OH)₄⁻. The stoichiometric equilibrium constants K _m for the aqueous speciation reactions were estimated. Two types of representations of the osmotic coefficients for the Li₂B₄O₇+LiCl+H₂O system are presented with ion-interaction models based on Pitzer’s equations with minor modifications: model (I) represents the φ _S data with six parameters based on considering the ion-interactions between three ionic species of Li⁺, Cl⁻, and B₄O₇²⁻, and model (II) for represents the φ _E data based on considering the equilibrium speciation. The parameters of models (I) and (II) are presented. The standard deviations for the two models are 0.0152 and 0.0298, respectively. Model (I) was more satisfactory than model (II) for representing the isopiestic data.     

Chemistry of ruthenium in N2P2X2 (X = Cl, Br) coordination sphere: Synthesis, characterization and reactivities

Reaction of 2-(phenylazo)pyridine (pap) with [Ru(PPh₃)₃X₂] (X = Cl, Br) in dichloromethane solution affords [Ru(PPh₃)₂(pap)X₂]. These diamagnetic complexes exhibit a weakdd transition and two intense MLCT transitions in the visible region. In dichloromethane solution they display a one-electron reduction of pap near − 0.90 V vs SCE and a reversible ruthenium(II)-ruthenium(III) oxidation near 0.70 V vs SCE. The [Ru^III(PPh₃)₂(pap)Cl₂]⁺ complex cation, generated by coulometric oxidation of [Ru(PPh₃)₂(pap)Cl₂], shows two intense LMCT transitions in the visible region. It oxidizes N,N-dimethylaniline and [Ru^II(bpy)₂Cl₂] (bpy = 2,2′-bipyridine) to produce N,N,N′,N′-tetramethylbenzidine and [Ru^III(bpy)₂Cl₂]⁺ respectively. Reaction of [Ru(PPh₃)₂(pap)X₂] with Ag⁺ in ethanol produces [Ru(PPh₃)₂(pap)(EtOH)₂]²⁺ which upon further reaction with L (L = pap, bpy, acetylacetonate ion(acac⁻) and oxalate ion (ox²⁻)) gives complexes of type [Ru(PPh₃)₂(pap)(L)]ⁿ⁺ (n = 0, 1, 2). All these diamagnetic complexes show a weakdd transition and several intense MLCT transitions in the visible region. The ruthenium(II)-ruthenium(III) oxidation potential decreases in the order (of L): pap > bpy > acac⁻ > ox²⁻. Reductions of the coordinated pap and bpy are also observed.     

Gas‐Phase Kinetics of Chlorosilylene Reactions II. ClSiH + C2H4: Absolute Rate Measurements and Quantum Chemical and RRKM Calculations for the Prototype π Addition Reaction

Time‐resolved studies of chlorosilylene, ClSiH, generated by the 193 nm laser flash photolysis of 1‐chloro‐1‐silacyclopent‐3‐ene, are carried out to obtain rate constants for its bimolecular reaction with ethene, C₂H₄, in the gas‐phase. The reaction is studied over the pressure range 0.13–13.3 kPa (with added SF₆) at five temperatures in the range 296–562 K. The second order rate constants, obtained by extrapolation to the high pressure limits at each temperature, fitted the Arrhenius equation: log(k^∞/cm³ molecule^?1 s^?1)=(?10.55±0.10) + (3.86±0.70) kJ mol^?1/RT ln10. The Arrhenius parameters correspond to a loose transition state and the rate constant at room temperature is 43 % of that for SiH₂ + C₂H₄, showing that the deactivating effect of Cl‐for‐H substitution in the silylene is not large. Quantum chemical calculations of the potential energy surface for this reaction at the G3MP2//B3LYP level show that, as well as 1‐chlorosilirane, ethylchlorosilylene is a viable product. The calculations reveal how the added effect of the Cl atom on the divalent state stabilisation of ClSiH influences the course of this reaction. RRKM calculations of the reaction pressure dependence suggest that ethylchlorosilylene should be the main product. The results are compared and contrasted with those of SiH₂ and SiCl₂ with C₂H₄.     

Theoretical study on reactions of cyclic-N3 with NO, NO2 and Cl2

In this article, we report our detailed mechanistic study on the reactions of cyclic-N₃ with NO, NO₂ at the G3B3//B3LYP/6-311+G(d) and CCSD(T)/aug-cc-pVTZ//QCISD/6-311+G(d)+ZPVE levels; the reactions of cyclic-N₃ with Cl₂ was studied at the G3B3//B3LYP/6-311+G(d) and CCSD(T)/aug-cc-pVTZ//QCISD/6-31+G(d)+ZPVE levels. Both of the singlet and triplet potential-energy surfaces (PESs) of cyclic-N₃ + NO, cyclic-N₃ + NO₂ and the PES of cyclic-N₃ + Cl₂ have been depicted. The results indicate that on singlet PESs cyclic-N₃ can undergo the barrierless addition–elimination mechanism with NO and NO₂ forming the respective dominant products N₂ + ¹cyclic-NON and ¹NNO(O) + N₂. Yet the two reactions on triplet PESs are much less likely to take place under room temperature due to the high barriers. For the cyclic-N₃ + Cl₂ reaction, a Cl-abstraction mechanism was revealed that results in the product cyclic-N₃Cl + Cl with an overall barrier as high as 14.7 kcal/mol at CCSD(T)/aug-cc-pVTZ//QCISD/6-31+G(d)+ZPVE level. So the cyclic-N₃ radical could be stable against Cl₂ at low temperatures in gas phase. The present results can be useful for future experimental investigation on the title reactions.     

Theoretical study on H2 elimination pathways of silylenoid H2SiLiF with CH4, NH3, H2O, HF, SiH4, PH3, H2S, and HCl

Ab initio molecular orbital calculations have been performed to explore the reaction potential energy surfaces of silylenoid H₂SiLiF with XH _n hydrides, where XH _n = CH₄, NH₃, H₂O, HF, SiH₄, PH₃, H₂S, and HCl. We have identified a previously unreported reaction pathway on each reaction surface, H₂SiLiF + H-XH _{n − 1} → H _n XSiLiF + H₂, which involves H₂ elimination following the initial formation of an association complex via a four-membered ring transition state to form the substituted three-membered ring silylenoid H _n XSiLiF and a H₂ molecule. This theoretical calculations suggest that (i) for H₂ eliminations there is a very clear trend toward lower activation barriers and more exothermic interactions on going from left to right along a given row in periodic table, and (ii) for the second-row hydrides, the H₂ elimination reactions are less exothermic than for the first-row hydrides and the reaction barriers are lower for X–S and Cl. Compared to the insertions of H₂SiLiF into XH _n , the H₂ elimination pathways should be unfavorable with higher barrier and lower exothermic.     

Theoretical study of the molecular ions SiH−5 and SiH−3

Ab initio HF and Cl calculations were performed to determine the equilibrium geometry of SiH^?₅ and SiH^?₃, the barrier for internal rotation (SiH^?₅) and inversion (SiH^?₃) and the stability of SiH^?₅ and further to study the effect of electron correlation on reaction energies. The gaussian-type basis included d and f functions on Si and a p set on II. The D_3h structures of SiH^?₅ is lower in energy than the C_4v structure by 2.9(3.2) kcal/mol (corresponding HF results in parentheses). SiH^?₃ has C_3v structure, the inner-ion barrier computed is 26.2 (27.3) kcal/mol. SiH^?₅ turns out to be stable with respect to SiH₄ + H^? by 20.3 (13.8) kcal/mol, but it is unstable with respect to SiH^?₃ ← H₂ by 6.3 (5.6) kcal/mol. These results show that electron correlation has a small effect on barriers of inversion (SiH^?₃) or pseudorotation (SiH^?₅), but may have a pronounced effect on reaction energies even if all systems involved have closed shells. The correlation energy contributions are analyzed in terms of intrapair and interpair terms in order to get a better understanding of the influence of correlation on reaction and activation energies.     

Analytical fitting of potential energy surfaces for the Hxy systems

Use of the London-Eyring-Polanyi + 3-Center + power-series (LEP -3C -PS ) analytical potential as a fit to potential energy surfaces (PES ) which are known numerically only are suggested. This analytical fit was performed for the diatomics-in-molecules + 3 Center (DIM -3C ) PES of HCl₂ and HI₂ systems. The HCl₂ analytical LEP -3C-PS potential was used for classical trajectory calculations of the Cl' + HCl → HCl' + Cl reaction. The rate constant obtained from these calculations for T = 358° K is 1.95 X 10⁹ cm³/mol sec which is close to the experimental value of 2.5 10⁹ cm³/mol sec.     

交叉分子束研究氯原子与硅烷的反应动力学

The dynamics of the Cl+SiH₄ reaction has been studied using the universal crossed molecular beam method. Angular resolved time-of-flight spectra have been measured for the channelSiH₃Cl+H. Product angular distributions as well as energy distributions in the center-of-mass frame were determined for the channel. Experimental results show that the SiH₃Clproduct is mainly backward scattered relative to the Cl atom beam direction, suggestingthat the channel takes place via a typical S_N2 type reaction mechanism.     

Investigation on the catalytic activity of doped low-percentage oxide catalysts Mn/ZnO obtained from oxalate precursor

The precursors with a low manganese content ≤ 0.07% Mn were synthesized by spontaneous crystallization from Zn²⁺, Mn²⁺ and C₂O₄ ²⁻-containing solutions. The initial ratio Zn²⁺:C₂O₄ ²⁻ = 1:1 and 1:2 influences the morphology and prevailing orientations of the crystallites in the oxalate samples. The presence of such small Mn content in the samples does not change the morphology or size of the crystals. The ZnO and Mn/ZnO oxides with manganese content from 0.51×10⁻² to 15.1×10⁻² Wt % are obtained after thermal decomposition of the oxalates. The oxides preserved the morphology of the precursors. The catalytic tests show that the pure ZnO has a poor activity for CO oxidation reaction. Its doping with Mn promotes the catalytic activity (up from twice to five times) in spite of the very low contents of the dopants. The observed increase of the activity depends on both dopant concentration and Zn²⁺:C₂O₄ ²⁻ ratio, probably due to the different mechanism of the manganese inclusion and different morphology of the oxides. The catalysts of the 1:2 series are more active in CO oxidation reaction.      

Photocatalytic degradation of methylene blue on Fe3+-doped TiO2 nanoparticles under visible light irradiation

Fe³⁺-doped TiO₂ composite nanoparticles with different doping amounts were successfully synthesized using sol-gel method and characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM) and ultravioletvisible spectroscopy (UV-Vis) diffuse reflectance spectra (DRS). The photocatalytic degradation of methylene blue was used as a model reaction to evaluate the photocatalytic activity of Fe³⁺/TiO₂ nanoparticles under visible light irradiation. The influence of doping amount of Fe³⁺ (ω: 0.00%–3.00%) on photocatalytic activities of TiO₂ was investigated. Results show that the size of Fe³⁺/TiO₂ particles decreases with the increase of the amount of Fe³⁺ and their absorption spectra are broaden and absorption intensities are also increased. Doping Fe³⁺ can control the conversion of TiO₂ from anatase to rutile. The doping amount of Fe³⁺ remarkably affects the activity of the catalyst, and the optimum efficiency occurs at about the doping amount of 0.3%. The appropriate doping of Fe³⁺ can markedly increase the catalytic activity of TiO₂ under visible light irradiation. __________ Translated from Journal of Northwest Normal University (Natural Science), 2006, 42(6): 55–56 [译自: 西北师范大学学报(自然科学版)]     

Mechanism and kinetics of the reaction of ozone with sodium chloride in aqueous solutions

It is shown experimentally that Cl⁻ appreciably accelerates ozone decomposition in water (τ_1/2 = 1.5 h versus 6 h in pure water). The decomposition of ozone in NaCl solutions includes the reversible reaction of ozone with the chloride ion (O₃ + Cl⁻ → O₃⁻ + Cl) as the key step, which is followed by the development of a chain reaction in which chain propagation is performed alternately by the chlorine atom Cl and its monoxide ClO. The current concentrations of the chlorine atom are rather low ([Cl] ∼ 10⁻¹⁴ mol/l). The overall process is satisfactorily described by a first-order rate law with respect to ozone. The decomposition of ozone in aqueous solutions of NaCl is not accompanied by the formation of products other than oxygen. In particular, no noticeable amounts of hypochlorites and chlorates are observed. This is particularly significant for medicinal applications of ozonized isotonic solutions.     

Rate constant for the reaction of OH radicals with CH3C(O)Cl determined by direct kinetic method

Summary The fast flow technique with OH resonance fluorescence detection has been applied at T = 298 ± 2 K to study the kinetics of the overall reaction: H + CH₃C(O)Cl → products (1) A rate constant value of k₁ = (1.02 ± 0.12) x 10¹⁰ cm³ mol^-1 s^-1 has been determined which is the first direct kinetic parameter reported for reaction (1) in the literature (the error given refers to 2σ accuracy).     

Radical–molecule reaction CH<Subscript>2</Subscript>Cl + NO<Subscript>2</Subscript>: a mechanistic study

The radical–molecule reaction mechanism of CH₂Cl with NO₂ has been explored theoretically at the B3LYP/6–311G(d,p) and MC–QCISD (single-point) levels of theory. Our results indicate that the title reaction proceeds mostly through singlet pathways, less go through triplet pathways. The initial association between CH₂Cl and NO₂ is found to be the carbon-to-nitrogen attack forming the adduct a H₂ClCNO₂ with no barrier, followed by isomerization to b ₁ H₂ClCONO-trans which can easily convert to b ₂ H₂ClCONO-cis. Subsequently, the most feasible pathway is the C–Cl and O–N bonds cleavage along with the N–Cl bond formation of b (b ₁ , b ₂ ) leading to product P ₁ CH₂O + ClNO, which can further dissociate to give P ₅ CH₂O + Cl + NO. The second competitive pathway is the 1,3-H-shift associated with O–N bond rupture of b ₁ to form P ₂ CHClO + HNO. Because the intermediates and transition states involved in the above two favorable channels all lie below the reactants, the CH₂Cl+NO₂ reaction is expected to be rapid, as is confirmed by experiment. The present results can lead us to understand deeply the mechanism of the title reaction and may be helpful for further experimental investigation of the reaction.     

Theoretical study of the C3S molecule

For the most stable linear isomer of C₃S in its X¹Σ⁺ state a six-dimensional potential energy surface (PES) has been calculated ab initio by coupled cluster – connected triples (CCSD(T)) method. The analytic form of the PES has been transformed in a quartic force field in dimensionless normal coordinates and employed in calculations of spectroscopic constants using second-order perturbation theory. The PES and the full kinetic energy operator in internal coordinates have been used to calculate variationally the anharmonic ro-vibrational energies for J=0 and J=1. The two experimental band origins of C₃S observed in the gas phase, ν₁ and ν₁+ν₅−ν₅, agree very well with the theoretical values. The anharmonic ro-vibrational levels, including the bending modes up to 2200 cm⁻¹, are reported. The singlet ground state PES has a saddle point at about 1.25 eV above the linear minimum and two other higher lying cyclic local minima. The only dipole- and spin-allowed electronic transition between 0 and 5 eV is calculated to be the ¹Π−X¹Σ⁺ transition with a vertical transition energy of 353.2 nm in good agreement with the matrix value of 378 nm. The dissociative paths C + C₂S, C₂ + CS and C₃ + S of low lying singlet and triplet states have been investigated. Electronic Supplementary Material: Supplementary material is available in the online version of this article at dx.doi.org/10.1007/s00214-005-0683-7 Dedicated to Professor H. Stoll.     

Theoretical study on the reaction mechanisms of CH2SH + NO reaction

The mechanisms for the CH₂SH + NO reaction were investigated on both of the singlet and triplet PES at the BMC-CCSD//B3LYP/6-311+G(d,p) level. The results indicate that the singlet PES is much lower than the triplet PES energetically; therefore, the reaction occurs on the singlet PES dominantly. The most favorable channel on the singlet PES takes place by a barrierless addition of N atom to CH₂SH radical to form HSCH₂NO. Subsequently, the rearrangement of the initial adduct HSCH₂NO (IM1) to form another intermediate IM3 via a four-center transition state, followed by the C–O bond fission in IM3 leading to the major product CH₂S + HNO. Due to high barriers, other product including HC(N)SH + HO, HON + CH₂S, and HNO + CHSH could be negligible. The direct abstraction channel was also determined to yield CH₂S + HON. With high barrier (33.3 kcal/mol), it is not competitive with the addition channel, in which all stationary points are lower than reactant energetically. While on the triplet PES, with the lowest barrier height (18.8 kcal/mol), the direct N-abstracted channel to form CH₂S + HNO is dominant. However, it is not competitive with the channels on the singlet PES. Our results are in good accordance with experimental conclusions that the reaction proceeds via addition mechanism.