A flash photolysis–resonance fluorescence kinetics study of ground-state sulfur atoms. IV. Rate parameters for reaction of S(3P) with propene and 1-butene

Using the technique of flash photolysis-resonance fluorescence, absolute rate constants have been measured for the reaction of S(³P) with propene and 1-butene. Variations in experimental conditions included the following: temperature (215–500°K); total pressure a factor of 10; olefin concentration, a factor of 6; flash intensity (S atom concentration), a factor of 10. It was found that over these variations in the experimental conditions only the temperature had a measureable effect on the bimolecular rate constant. The derived Arrhenius rate expressions for the reactions (2) and (3) were as follows: temperature range 214–500°K Units are cm³ molec^?1 s^?1.     

A flash photolysis–resonance fluorescence kinetics study of the reactions of ground-state sulfur atoms. V. Rate parameters for the reaction of S(3P)with cis-2-butene and tetramethylethylene

Rate parameters for the reaction of ground-state atomic sulfur, S(³P), with the olefins cis-2-butene and tetramethylethylene have been determined over a temperature range of ∽280°K. A major finding of this study was that the rate constants for both reactions showed negative temperature dependencies. When k is expressed in the form of an Arrhenius equation, this necessarily leads to negative activation energies: k₁ = (4.68 ± 0.70) × 10^?12 exp ^{(+0.23 ± 0.09 kcal/mole)/RT} (219°-500°K) k₂ = (4.68 ± 1.70) × 10^?12 exp ^{(+1.29 ± 0.23 kcal/mole)/RT} (252°-500°K) Units are cm³ molec^?1s^?1. When a threshold energy of 0.0 kcal/mole is assumed for reaction (2), the temperature dependence of the preexponential term has a value of T^?2. Making the usual simplifying assumptions, neither collision theory nor transition state theory leads to a preexponential factor with a strong enough negative temperature dependence. A comparison of these results with those derived from studies of the reactions of atomic oxygen, O(³P), with the same olefins shows that in both studies simple bimolecular processes were being examined. Also discussed are the possible experimental and theoretical ramifications of these new results.     

A flash photolysis–resonance fluorescence kinetics study of ground-state sulfur atoms: I. Absolute rate parameters for reaction of S(3P) with O2(3Σ).

The flash photolysis–resonance fluorescence technique has been used to measure the reaction of ground-state sulfur atoms with molecular oxygen as a function of both temperature and total pressure. The most suitable source of S(³P) for this study was found to be COS in the presence of CO₂, as a diluent gas and with the photolysis flash filtered so as to remove all radiation of wavelengths below 1650 Å. Under these conditions, it was found that over the temperature range of 252–423°K the rate data could be fit to a simple Arrhenius-type equation of the form Units are cm³ molec^?1 s^?1. The small A-factor for this reaction, the lack of any pressure dependence, and the direct observation of the production of O(³P) with increasing reaction time suggest that the S(³P) atom attacks the O₂(³Σ) molecule end-on forming SOO which rapidly falls apart to form SO (³Σ) and O(³P).     

A flash photolysis resonance fluorescence kinetics study of ground-state sulfur atoms. III. Rate parameters for reaction of S(3P) with ethylene episulfide

Absolute rate constants for the reaction of S(³P) with ethylene episulfide were measured over a C₂H₄S concentration range of 5, a total pressure of 20–200 tort, and a flash intensity range of ?4. Over this range of variables, the bimolecular rate constant was found to be invariant. Because of limitations imposed by the physical properties of the reactant C₂H₄S, temperature variations were necessarily held to the range 298–355°K. The bimolecular rate constant was found to be invariant over this limited temperature range, having a value of (4.47 ± 0.26) × 10^?11 cm³ molec.^?1 sec^?1. The possible influence of this reaction in studies of the S(³P)–ethylene system are discussed.     

Crossed-beam radical-radical reaction dynamics of O(3P)+C3H3-->H(2S)+C3H2O

The radical-radical oxidation reaction, O(3P)+C3H3 (propargyl)-->H(2S)+C3H2O (propynal), was investigated using vacuum-ultraviolet laser-induced fluorescence spectroscopy in a crossed-beam configuration, together with ab initio and statistical calculations. The barrierless addition of O(3P) to C3H3 is calculated to form energy-rich addition complexes on the lowest doublet potential energy surface, which subsequently undergo direct decomposition steps leading to the major reaction products, H+C3H(2)O (propynal). According to the nascent H-atom Doppler-profile analysis, the average translational energy of the products and the fraction of the average transitional energy to the total available energy were determined to be 5.09+/-0.36 kcal/mol and 0.077, respectively. On the basis of a comparison with statistical prior calculations, the reaction mechanism and the significant internal excitation of the polyatomic propynal product can be rationalized in terms of the formation of highly activated, short-lived addition-complex intermediates and the adiabaticity of the excess available energy along the reaction coordinate.     

Time-dependent quantum study of the kinetics of the H(2S) + FO(2II) OH(2II) + F(2P) reaction

Quantum mechanical wave packet calculations are carried out for the H((2)S) + FO((2)II) --> OH((2)II) + F((2)P) reaction on the adiabatic potential energy surface of the ground (3)A' triplet state. The state-to-state and state-to-all reaction probabilities for total angular momentum J = 0 have been calculated. The probabilities for J > 0 have been estimated from the J = 0 results by using J-shifting approximation based on a capture model. Then, the integral cross sections and initial state-selected rate constants have been calculated. The calculations show that the initial state-selected reaction probabilities are dominated by many sharp peaks. The reaction cross section does not manifest any sharp oscillations and the initial state-selected rate constants are sensitive to the temperature.     

Synthesis and structure of the cluster μ3-sulfido-μ-–(diethylphosphorodithioato-S,S'-)-allylthioureocyclo-tris-[ (μ-sulfido)-χ-(diethylphosphorodithioato-S,S')-molybdenum(IV)], Mo3S4(C4H10O2S2P)4(C4H8N2S)

Title compound, M_r =1273.16, was synthesized by a substitution reaction and its crystal is triclinic belonging to space group P1 with cell parameters: a =13.944(2), b =14.143(7), c =14.233(3) Å, α =77.35(3)°, β =69.94(2)°, γ =63.50(3)°, V=2351(1) ų, Z=2, D_c =1.799g cm^?2. Room temperature, graphite-filtered Mo K_α radiation (λ =0.71073Å) was used for data collection. μ =14.988 cm^?1, F(000) =1280, R=0.051 for 7025 observed reflections. The crystal consists of decrete cluster molecules containing a cluster core [Mo₂(μ₃-S)]¹⁰⁺ with three μ-S, one μ-dtp(dtp =[S₂P(OC₂H₅)]^2-), three χ-dtp and one allylthioureo to form a local six-coordinated sphere around each Mo atom. The bonds of cluster skeleton [Mo₃(μ₃-S)(μ-S)₃]⁴⁺, Mo? Mo 2.744～2.766, Mo—(μ₂-S) 2.340～2.342 and Mo—(μ-S)2.272～2.296 Å, are comparable with those found in the related analogues.     

The reaction of S(3P) atoms with nitric oxide

The flash photolysis–vacuum ultraviolet kinetic absorption spectroscopy technique has been used to measure the absolute rate constant for the reaction of ground state S(³P) atoms withnitric oxide,\documentclass{article}\pagestyle{empty}\begin{document}${\rm S}\left({^{\rm 3} P} \right) + {\rm NO}\mathop {\longrightarrow}\limits^{\rm M} {\rm SNO}\left({{\rm M} = {\rm CO}_2} \right)$\end{document} as a function of nitric oxide concentration and total pressure. The rateconstant was determined to be 1.9±0.1 × 10¹¹ 1²/mol².sec at 298°K, with a high-pressure limit of 9.3 ± 2.1×10⁹ l/mol·sec^?1. The observed kinetics are consistent with a termolecular energy transfer mechanism.     

Quantum chemical and theoretical kinetics study of the O(3P) + C2H2 reaction: a multistate process

The potential energy surfaces of the two lowest-lying triplet electronic surfaces 3A' and 3A' for the O(3P) + C2H2 reaction were theoretically reinvestigated, using various quantum chemical methods including CCSD(T), QCISD, CBS-QCI/APNO, CBS-QB3, G2M(CC,MP2), DFT-B3LYP and CASSCF. An efficient reaction pathway on the electronically excited 3A' surface resulting in H(2S) + HCCO(A2A') was newly identified and is predicted to play an important role at higher temperatures. The primary product distribution for the multistate multiwell reaction was then determined by RRKM statistical rate theory and weak-collision master equation analysis using the exact stochastic simulation method. Allowing for nonstatistical behavior of the internal rotation mode of the initial 3A' adducts, our computed primary-product distributions agree well with the available experimental results, i.e., ca. 80% H(2S) + HCCO(X2A' + A2A') and 20% CH2(X3B1) + CO(X1sigma+) independent of temperature and pressure over the wide 300-2000 K and 0-10 atm ranges. The thermal rate coefficient k(O + C2H2) at 200-2000 K was computed using multistate transition state theory: k(T) = 6.14 x 10(-15)T (1.28) exp(-1244 K/T) cm3 molecule(-1) s(-1); this expression, obtained after reducing the CBS-QCI/APNO ab initio entrance barriers by 0.5 kcal/mol, quasi-perfectly matches the experimental k(T) data over the entire 200-2000 K range, spanning 3 orders of magnitude.     

C(3P)与H2S反应的反应机理

The mechanisms of the C(3P)+H 2S→HCS+H and C(3P)+H 2S → HSC+H reactions have been studied at the UMP2/6-31G(d,p),UMP2/6-311G(d,p),and G2 levels, and six transition states and three intermediates have been located along the reaction paths. The predicted path for the C(3P)+H2S→HCS+H reaction is: C(3P)+H2S→IM1→TS1→IM2→TS4→HCS+H, in line with the reaction process suggested by Lee et al. [1] in which only the intermediates were given. Our energetic results indicate that the C(3P)+H2S→HCS+H reaction is more favorable than the C(3P)+H 2S→HSC+H reaction, in agreement with experiment.     

Syntheses and Characterizations of (4-NH2C6H4S)4Sn and [(4-NH2C6H4S)2(4-NH3C6H4S)2Sn]Cl2

1INTRODUCTIONInrecentyears,theresearchesontinsulfidemateri-alshavedrawnchemists’attentionowningtotheirpo-tentialapplicationsasphotovoltaicmaterials,hologra-phicrecordingsystem[1,,solarcontroldevices[3]and2]semiconductormaterials.Ageneralmethodtopreparetinsulfidesisthechemicalvapourdepositionfromdi-scretesimpletin-sulfidecomplexes,suchas(PhS)4Sn,Sn(SCy)4and[CF3(CF2)5S]4Sn[4].Duringoureffortinsynthesizingtin-sulphurcomplexes[5],weobtainedtwomononucleartincomplexes,(4-NH2C6H4S)4Sn1an…     

Earth Alkaline Tetrathiosquarates. II. – Syntheses and Crystal Structures of SrC4S4·4 H2O and Ba4K2(C4S4)5·16 H2O

Concentrated aqueous solutions of strontium chloride and barium chloride, respectively, allow on addition of the potassium salt of tetrathiosquarate, K₂C₄S₄·H₂O, the isolation of the earth alkaline salts SrC₄S₄·4 H₂O ( 1 ) and Ba₄K₂(C₄S₄)₅·16 H₂O ( 2 ), both as dark red crystals. The crystal structure determinations ( 1 : orthorhombic, Pnma, a = 8.149(1), b = 12.907(2), c = 10.790(2) Å, Z = 4; 2 : orthorhombic, Pbca, a = 15.875(3), b = 21.325(5), c = 16.119(1) Å, Z = 4) show the presence of C₄S₄²⁻ ions with only slightly distorted D_4h symmetry having average C–C and C–S bond lengths of 1.41Å and 1.681Å for 1 and 1.450Å and 1.657Å for 2 . The structure of 1 contains concatenated edge‐sharing Sr(H₂O)₆S₂ polyhedra. The Sr²⁺ ions are in eight‐fold coordination with Sr–O distances of 2.50–2.72Å and Sr–S distances of 3.21Å, (C₄S₄)²⁻ acts as a chelating ligand towards Sr²⁺. The structure is closely related to the previously reported Ca²⁺ containing analogue, which is of lower symmetry belonging to the monoclinic crystal system. A supergroup‐subgroup relation between the space groups of both structures is present. The structure of 2 is made up of Ba²⁺ and K⁺ ions in eight and nine‐fold coordination by H₂O molecules and (C₄S₄)²⁻ ions which act as chelating ligands towards one cation and bridging between two cations. The coordination polyhedra of the cations are connected by common edges and corners in two dimensions to layers which are connected by tetrathiosquarate ions to a three‐dimensional network. The infrared and Raman spectra show bands typical for the molecular building units of the two compounds.     

Quantum dynamics study on the product branching for the C(3P) + C2H2 reaction: cyclic-C3H versus linear-C3H

Reduced-dimensionality quantum reactive scattering calculations for the C(3P) + C2H2 reaction have been carried out in order to understand the product branching dynamics of cyclic-C3H + H and linear-C3H + H. Our model treats only two degrees of freedom but can explicitly describe both of the C3H isomer product channels. The lowest triplet potential energy surface has been obtained by the hybrid density-functional method at the B3LYP/6-31G(d,p) level of theory. The calculated reaction probabilities were found to be dominated by resonance consistent with the complex-formation potential, and the results show that cyclic-C3H is preferentially formed via the cyclic-C3H2 intermediate produced by insertion of C(3P) into the CC bond. We have found that the isomerization from the cyclic-C3H2 to linear-C3H2 intermediate is suppressed by a barrier separating potential wells corresponding to these two intermediates. It has also been found that the energy dependence of the calculated total reaction cross section is in good agreement with the result of crossed molecular beam experiments.     

2J(P,C) and 3J(P,C) Coupling Constants in Some New Phosphoramidates. Crystal Structures of CF3C(O)N(H)P(O)[N(CH3)(CH2C6H5)]2 and 4‐NO2‐C6H4N(H)P(O)[4‐CH3‐NC5H9]2

Some new phosphoramidates were synthesized and characterized by ¹H, ¹³C, ³¹P NMR, IR spectroscopy and elemental analysis. The structures of CF₃C(O)N(H)P(O)[N(CH₃)(CH₂C₆H₅)]₂ ( 1 ) and 4‐NO₂‐C₆H₄N(H)P(O)[4‐CH₃‐NC₅H₉]₂ ( 6 ) were confirmed by X‐ray single crystal determination. Compound 1 forms a centrosymmetric dimer and compound 6 forms a polymeric zigzag chain, both via ‐N‐H…O=P‐ intermolecular hydrogen bonds. Also, weak C‐H…F and C‐H…O hydrogen bonds were observed in compounds 1 and 6 , respectively. ¹³C NMR spectra were used for study of ²J(P,C) and ³J(P,C) coupling constants that were showed in the molecules containing N(C₂H₅)₂ and N(C₂H₅)(CH₂C₆H₅) moieties, ²J(P,C)>³J(P,C). A contrast result was obtained for the compounds involving a five‐membered ring aliphatic amine group, NC₄H₈. ²J(P,C) for N(C₂H₅)₂ moiety and in NC₄H₈ are nearly the same, but ³J(P, C) values are larger than those in molecules with a pyrrolidinyl ring. This comparison was done for compounds with six and seven‐membered ring amine groups. In compounds with formula XP(O)[N(CH₂R)(CH₂C₆H₅)]₂, ²J(P,CH₂)_benzylic>²J(P,CH₂)_aliphatic, in an agreement with our previous study.     

Synthesis and Crystal Structures of New Antimony Polysulfido Complexes: [P(C6H5)4]3Sb3S25 and [P(C6H5)4]2Sb2S15 · 2(C3N2H6)

Reaction of elemental antimony with sulfur under mild hydrothermal conditions yielded different polysulfido-clusters of antimony. These were isolated as tetraphenylphosphonium salts [P(C₆H₅)₄]₃Sb₃S₂₅ and [P(C₆H₅)₄]₂Sb₂S₁₅ · 2(C₃N₂H₆) and their crystal structures were determined. In the first compound two different polysulfide anions are observed, Sb₂S₁₇^2– and Sb₂S₁₆^2–, whereas the second contains the Sb₂S₁₅^2– complex. These dinuclear anions show as a common building principle two ψ-trigonal bipyramidal coordinated Sb centers bridged by two S_x^2– units and an additional S_x^2– chelate ligand bound to each Sb center giving a tricyclic structure.