Structures of Stoichiometric Sodium Oxide Cluster Cations Studied by Ion Mobility Mass Spectrometry

Structures of stable compositions of sodium oxide cluster cations (Na_nO_m⁺,n≤11) have been investigated by ion mobility mass spectrometry. Stoichiometric compositions series, Na(Na₂O)_(n-1)/2⁺ (n=3, 5, 7, 9, and 11), were observed as stable composition series, and NaO(Na₂O)_(n-1)/2⁺ series (n=5, 7, 9, and 11) were observed as secondary stable series in the mass spectra. To assign the structures of these cluster ion series, collision cross sections between the ions and helium buffer gas were determined experimentally from the ion mobility measurements. Theoretical collision cross sections were also calculated for optimized structures of these compositions. Finally, the structures of Na(Na₂O)_(n-1)/2⁺ and NaO(Na₂O)_(n-1)/2⁺ were assigned to those having similar structural frames for each n except for n=9. All bonds in the assigned structures of Na(Na₂O)_(n-1)/2⁺ were between sodium and oxygen. On the other hand, there was one O-O bond in addition to Na-O bonds in NaO(Na₂O)_(n-1)/2⁺. This result indicates that NaO(Na₂O)_(n-1)/2⁺ have a peroxide ion (O₂^2-) as a substitute for an oxide ion (O^2-) of Na(Na₂O)_(n-1)/2⁺. As a result, both stable series, Na(Na₂O)_(n-1)/2⁺ and NaO(Na₂O)_(n-1)/2⁺, are closed-shell compositions. These closed-shell characteristics have a strong influence on the stability of sodium oxide cluster cations.     

catena‐Poly[tris(ethylenediamine‐κ2N,N′)nickel(II) [[trithiocyanato‐κ3N‐sodium(I)]‐μ‐aqua‐κ2O:O]]

The title complex, {[Ni(C₂H₈N₂)₃][Na(NCS)₃(H₂O)]}_n, con­sists of discrete [Ni(en)₃]²⁺ dications (en is ethyl­enedi­amine) and polymeric [(H₂O)_0.5Na(NCS)₃(H₂O)_0.5]_n^2n? anions. The compound crystallizes in space group Pc1. The Ni^II atom lies on a threefold axis and has a distorted octahedral coordination geometry. The Na⁺ cation also lies on a site with imposed crystallographic threefold symmetry and is coordinated by the thio­cyanate N atoms (the thio­cyanates are in general posi­tions), by one water mol­ecule with crystallographically imposed 32 symmetry and by a second water mol­ecule with crystallographically imposed symmetry. The unique Na atom thus has trigonal–bipyramidal coordination. The O atoms of the water mol­ecules bridge the Na⁺ cations to form one‐dimensional polymeric chains in the crystal structure. The [Ni(en)₃]²⁺ dications are distributed around and between the chains and are linked to them via N—H?S hydrogen bonds.     

Proton and sodium ion affinities of glycine and its sodium salt in the gas phase. Ab initio calculations

The energies of protonation and Na⁺ cationization of glycine (GLY) and its (GLY ? H + Na) salt in the gas phase were calculated using ab inltio calculations. The proton affinity of GLY, valued at the MP2/6–31G*//3-21G level, is 937 kJ mol^?1. The amino function is confirmed to be the most favourable site of protonation: ‘proton affinities’ of the carbonyl and hydroxyl functions are calculated to be 75 and 180 kJ mol^?1, respectively, lower than that of NH₂ at the MP2/6-31G*//3–21G level. Calculations performed up to the MP2/6–31G*//3–21G level give the Na⁺ affinity of GLY as 189 kJ mol^?1 and the H⁺ and Na⁺ affinities of (GLY – H + Na) as 1079 and 298 kJ mol^?1, respectively. The geometries of all neutral and protonated species optimized with the 3–21G basis set are described. Both H* and Na⁺ cations complex preferably between the nitrogen atom and the carbonyl oxygen atom, leading to pseudo-five-membered ring structures in which Na? O and Na? N bonds lengths are greater than 2 Å.     

Cross section for the photochemical formation of the NaZn (22Π) excimer

We studied the conditions for the photochemical formation of the NaZn excimer in the excited 2²Π state using Na₂(2¹Π _u )+Zn→NaZn(2²Π)+Na reaction. The Na-Zn vapor mixture was prepared in the heat-pipe oven with the well defined column density and temperature. The Na and Zn atom densities in the vapor mixture were controlled by the preparation of the alloy with different mole fraction ratios of the relevant components in the solid phase. The Na densities were determined from the total absorption coefficient at Na₂ X-B and X-A bands. The cross section for photochemical formation of the NaZn in the 2²Π state is estimated to be 17·10^?16 cm² for the laser excitation at 308 nm, measured relative to the cross section of 470·10^?16 cm² for collisional energy transfer Na₂(2¹Π _u )+Na→Na₂(2³Π _g )+Na published by Mehdizadeh et al. [2].     

A Highly Oxidizing and Isolable Oxoruthenium(V) Complex [RuV(N4O)(O)]2+: Electronic Structure,Redox Properties,and Oxidation Reactions Investigated by DFT Calculations

The electronic structure and redox properties of the highly oxidizing, isolable Ru^V?O complex [Ru^V(N₄O)(O)]²⁺, its oxidation reactions with saturated alkanes (cyclohexane and methane) and inorganic substrates (hydrochloric acid and water), and its intermolecular coupling reaction have been examined by DFT calculations. The oxidation reactions with cyclohexane and methane proceed through hydrogen atom transfer in a transition state with a calculated free energy barrier of 10.8 and 23.8 kcal mol^?1, respectively. The overall free energy activation barrier (ΔG^≠=25.5 kcal mol^?1) of oxidation of hydrochloric acid can be decomposed into two parts: the formation of [Ru^III(N₄O)(HOCl)]²⁺ (ΔG=15.0 kcal mol^?1) and the substitution of HOCl by a water molecule (ΔG^≠=10.5 kcal mol^?1). For water oxidation, nucleophilic attack on Ru^V?O by water, leading to O? O bond formation, has a free energy barrier of 24.0 kcal mol^?1, the major component of which comes from the cleavage of the H? OH bond of water. Intermolecular self‐coupling of two molecules of [Ru^V(N₄O)(O)]²⁺ leads to the [(N₄O)Ru^IV? O₂? Ru^III(N₄O)]⁴⁺ complex with a calculated free energy barrier of 12.0 kcal mol^?1.     

Monohydration selectivity mechanism of alkali cations in the potassium channel of excitable biomembranes

Nonempirical quantum chemical method Hartree–Fock–Roothan LCAO SCF MO in a two-exponent Dunning basis with the use of an extended set of Gaussian functions by Huzinaga–Dunning with consideration of electron correlation according to the Meller–Plesset theory of excitations of the second order was used to study monohydrates of Li⁺, Na⁺, K⁺, and HCOO^? ions. The indicated basis was supplemented with polarization functions of d-type on the O atom and of p-type on the hydrogen atom as well as with diffusion functions of p-type on the oxygen atom. It has been found that binding energies of the water molecule with Li⁺, Na⁺ appeared to be higher and with K⁺ lower than with HCOO^? · H₂O. Potential curve shapes of K⁺ + H₂O and HCOO^? + H₂O reactions are shown to be similar. The molecular mechanism of K⁺ channel selectivity of an excitable membrane is explained on the basis of the obtained calculations.     

Mechanism of the oxidation reaction of Cu with N2O via nonadiabatic electron transfer

We treat the present work as an attempt to elucidate the mechanism of the oxidation reaction of the Cu atom by nitrous oxide based on our recent work (Kryachko, E. S.; Vinckier, C.; Nguyen, M. T. J Chem Phys 2001, 114, 7911) on the electron attachment to this molecule. We suggest that the title reaction in its Arrhenius regime occurs via the nonadiabatic electron transfer from Cu to the oxygen atom at the crossing of the potential energy surfaces Cu(4s ²S_1/2) + N₂O(X ¹Σ⁺) and Cu⁺ + N₂O^?, where the latter is linked to the complex N₂O^? originated from the higher‐energy T‐shape N₂O molecule and discovered in the aforementioned work. The calculations performed in the present work using a variety of quantum chemical methods support the proposed model. We also show the existence of other reaction pathways of the title reaction that, we believe, contribute to its non‐Arrhenius behavior observed experimentally at T > 1190 K. © 2002 Wiley Periodicals, Inc. Int J Quantum Chem, 2002     

Direct observation of the angular distribution of the chemiluminescence from Ba + N2O → BaO + N2

The angular distribution of the chemiluminescent reaction Ba + N₂O → BaO + N₂ has been investigated by photographing directly the chemiluminescence from this reaction in a crossed beam experiment. It was found that the lifetime of the reactively scattered chemiluminescent BaO molecules is sufficiently long (≈ 10^?s δ) to allow the observation of the angular distribution. From the dependence of this distribution on R and ? where R is the distance from the scattering center and ? the laboratory scattering angle, we conclude that under single collision conditions the chemiluminescence arises preferentially from highly excited vibrational-rotational levels of the A′¹ Π state of BaO.     

HTFFR kinetics studies: A chemiluminescence titration method for the determination of absolutes Sn concentrations

Absolute gas phase Sn concentrations in the range 1 × 10¹³ ? [Sn] ? 1 × 10¹⁴ ml^?1 have been determined utilizing a technique based on the rapid (at T ? 900 K) titration reaction Sn + NO₂ → SnO + NO (k(900–1100 K) ≈ 1 × 10^?10 ml molecule^?1 s^?1) and the chemiluminescent indicator reaction Sn + N₂O → SnO + N₂ + hv(SnO a³ Σ-X¹Σ).     

Sodium 2‐nitro­ethanaloximate forms a layered‐framework structure

In the title compound, [Na(C₂H₃N₂O₃)], the Na⁺ cation lies on a centre of inversion in space group P2₁/m and all the atoms of the anion lie on a mirror plane. Na is octahedrally coordinated by four O and two N atoms from six different anions and each anion is coordinated to six different Na⁺ cations, forming chains of confacial octahedra which link the anion layers. Within these layers, the individual anions are linked by both O—H?O and C—H?O hydrogen bonds.     

Dual Metal Active Sites in an Ir1/FeOx Single‐Atom Catalyst: A Redox Mechanism for the Water‐Gas Shift Reaction

Herein, we report a theoretical and experimental study of the water‐gas shift (WGS) reaction on Ir₁/FeO_x single‐atom catalysts. Water dissociates to OH* on the Ir₁ single atom and H* on the first‐neighbour O atom bonded with a Fe site. The adsorbed CO on Ir₁ reacts with another adjacent O atom to produce CO₂, yielding an oxygen vacancy (O_vac). Then, the formation of H₂ becomes feasible due to migration of H from adsorbed OH* toward Ir₁ and its subsequent reaction with another H*. The interaction of Ir₁ and the second‐neighbouring Fe species demonstrates a new WGS pathway featured by electron transfer at the active site from Fe³⁺?O???Ir²⁺?O_vac to Fe²⁺?O_vac???Ir³⁺?O with the involvement of O_vac. The redox mechanism for WGS reaction through a dual metal active site (DMAS) is different from the conventional associative mechanism with the formation of formate or carboxyl intermediates. The proposed new reaction mechanism is corroborated by the experimental results with Ir₁/FeO_x for sequential production of CO₂ and H₂.     

O + NNH: A possible new route for NOX formation in flames

We propose a new high temperature pathway for NO formation that involves the reaction of NNH with oxygen atoms. This reaction forms the HNNO* energized adduct via a rapid combination reaction; HNNO* then rapidly dissociates to NH + NO. The rate constant for O + NNH ? NH + NO is calculated via a QRRK chemical activation analysis to be 3.3 × 10¹⁴ T^?0.23exp(+510/T) cm³ mol^?1 s^?1. This reaction sequence can be an important or even major route to NO formation under certain combustion conditions. The presence of significant quantities of NNH results from the reaction of H with N₂. The H + N₂ ? NNH reaction is only ca. 6 kcal/mol endothermic with a relatively low barrier. The reverse reaction, NNH dissociation, has been reported in the literature to be enhanced by tunneling. Our analysis of NNH dissociation indicates that tunneling dominates. We report a two-term rate constant for NNH dissociation: 3.0 × 10⁸ + [M] {1.0 × 10¹³T^0.5exp(?1540/T)} s^?1. The first term accounts for pressure-independent tunneling from the ground vibrational state, while the second term accounts for collisional activation to higher vibration states from which tunneling can also occur. ([M] is the total concentration in units of mol cm^?3.) Use of this dissociation rate constant and microscopic reversibility results in a large rate constant for the H + N₂ reaction. As a result, we find that NNH ? H + N₂ can be partially equilibrated under typical combustion conditions, resulting in NNH concentrations large enough for it to be important in bimolecular reactions. Our analysis of such reactions suggests that the reaction with oxygen atoms is especially important. © 1995 John Wiley & Sons, Inc.     

A temperature‐dependent kinetics study of the reaction of O(3PJ) with (CH3)2SO

A laser flash photolysis–resonance fluorescence technique has been employed to investigate the kinetics of the reaction of ground state oxygen atoms, O(³P_J), with (CH₃)₂SO (dimethylsulfoxide) as a function of temperature (266–383 K) and pressure (20–100 Torr N₂). The rate coefficient (k_R1) for the O(³P_J) + (CH₃)₂SO reaction is found to be independent of pressure and to increase with decreasing temperature. The following Arrhenius expression adequately describes the observed temperature dependence: k_R1(T) = (1.68 ± 0.76) × 10_?12 exp[(445 ± 141)/T] cm³ molecule^?1 s^?1, where the uncertainties in Arrhenius parameters are 2σ and represent precision only. The absolute accuracy of each measured rate coefficient is estimated to be ±30%, and is limited predominantly by the uncertainties in measured (CH₃)₂SO concentrations. The observed temperature and pressure dependencies suggest that, as in the case of O(³P_J) reactions with CH₃SH and (CH₃)₂S, reaction occurs by addition of O(³P_J) to the sulfur atom followed by rapid fragmentation of the energized adduct to products. The O(³P_J) + (CH₃)₂SO reaction is fast enough so that it could be a useful laboratory source of the CH₃SO₂ radical if this species is produced in significant yield. © 2002 Wiley Periodicals, Inc. Int J Chem Kinet 34: 156–161, 2002; DOI 10.1002/kin.10040     

Heterogeneous recombination of O + CO on solid CO2 at 77 K

Heterogeneous recombination of O + CO → CO₂ over a solid CO₂ surface at 77 K was investigated. A modified discharge flow setup was used to generate low O atom concentrations by the reaction N + NO → N₂ + O(³P). The O atom concentrations were measured upstream and downstream of the solid CO₂ substrate using resonance fluorescence by monitoring the unresolved 130.3 nm triplet transition ³S₁ ? ³P_2,1,0 at the two fixed points. CO₂ formed was determined by measuring the β activity from C¹⁴O₂ produced from CO containing C¹⁴O as a reactant gas. The CO₂ formation was found to be first order in CO and independent of O atom concentration over the entire range of 4.3 × 10¹² to 1.9 × 10¹⁴ cm^?3 and 1.2 × 10¹¹ to 5.6 × 10¹² cm^?3 for CO and O respectively. The first order recombination coefficient, λ_CO was found to be 1.4 (±.38) × 10^?5.     

Syntheses and structural determinations of the nine-coordinate rare earth metal: Na4[DyIII(dtpa)(H2O)]2·16H2O,Na[DyIII(edta)(H2O)3]·3.25H2O and Na3[DyIII(nta)2(H2O)]·5.5H2O

Three complexes, Na₄[Dy^III(dtpa)(H₂O)]₂?·?16H₂O, Na[Dy^III(edta)(H₂O)₃]?·?3.25H₂O and Na₃[Dy^III (nta)₂(H₂O)]?·?5.5H₂O, have been synthesized in aqueous solution and characterized by FT–IR, elemental analyses, TG–DTA and single-crystal X-ray diffraction. Na₄[Dy^III(dtpa)(H₂O)]₂?·?16H₂O crystallizes in the monoclinic system with P2₁/n space group, a?=?18.158(10)?Å, b?=?14.968(9)?Å, c?=?20.769(12)?Å, β?=?108.552(9)°, V?=?5351(5)?ų, Z?=?4, M?=?1517.87?g?mol^?1, D _c?=?1.879?g?cm^?3, μ?=?2.914?mm^?1, F(000)?=?3032, and its structure is refined to R ₁(F)?=?0.0500 for 9384 observed reflections [I?>?2σ(I)]. Na[Dy^III(edta)(H₂O)₃]?·?3.25H₂O crystallizes in the orthorhombic system with Fdd2 space group, a?=?19.338(7)?Å, b?=?35.378(13)?Å, c?=?12.137(5)?Å, β?=?90°, V?=?8303(5)?ų, Z?=?16, M?=?586.31?g?mol^?1, D _c?=?1.876?g?cm^?3, μ?=?3.690?mm^?1, F(000)?=?4632, and its structure is refined to R ₁(F)?=?0.0307 for 4027 observed reflections [I?>?2σ(I)]. Na₃[Dy^III(nta)₂(H₂O)]?·?5.5H₂O crystallizes in the orthorhombic system with Pccn space group, a?=?15.964(12)?Å, b?=?19.665(15)?Å, c?=?14.552(11)?Å, β?=?90°, V?=?4568(6)?ų, Z?=?8, M?=?724.81?g?mol^?1, D _c?=?2.102?g?cm^?3, μ?=?3.422?mm^?1, F(000)?=?2848, and its structure is refined to R ₁(F)?=?0.0449 for 4033 observed reflections [I?>?2?σ(I)]. The coordination polyhedra are tricapped trigonal prism for Na₄[Dy^III(dtpa)(H₂O)]₂?·?16H₂O and Na₃[Dy^III(nta)₂(H₂O)]?·?5.5H₂O, but monocapped square antiprism for Na[Dy^III(edta)(H₂O)₃]?·?3.25H₂O. The crystal structures of these three complexes are completely different from one another. The three-dimensional geometries of three polymers are 3-D layer-shaped structure for Na₄[Dy^III(dtpa)(H₂O)]₂?·?16H₂O, 1-D zigzag type structure for Na[Dy^III(edta)(H₂O)₃]?·?3.25H₂O and a 2-D parallelogram for Na₃[Dy^III(nta)₂(H₂O)]?·?5.5H₂O. According to thermal analyses, the collapsing temperatures are 356°C for Na₄[Dy^III(dtpa)(H₂O)]₂?·?16H₂O, 371°C for Na[Dy^III(edta)(H₂O)₃]?·?3.25H₂O and 387°C for Na₃[Dy^III(nta)₂(H₂O)]?·?5.5H₂O, which indicates that their crystal structures are very stable.     

Ions Can Move a Proton‐Coupled Electron‐Transfer Reaction into Tunneling Regime

The effects of charged species on proton‐coupled electron‐transfer (PCET) reaction should be of significance for understanding/application of important chemical and biological PCET systems. Such species can be found in proximity of activated complex in a PCET reaction, although they are not involved in the charge transfer process. Reported here is the first study of the above‐mentioned effects. Here, the effects of Na⁺, K⁺, Li⁺, Ca²⁺, Mg²⁺, and Me₄N⁺ observed in PCET reaction of ascorbate monoanions with hexacyanoferrate(III) ions in H₂O reveal that, in presence of ions, this over‐the‐barrier reaction entered into tunneling regime. The observations are: a) dependence of the rate constant on the cation concentration, where the rate constant is 71 (at I = 0.0023), and 821 (at 0.5M K⁺), 847 (at 1.0M Na⁺), and 438 M ^?1 s^?1 (at 0.011M Ca²⁺); b) changes of kinetic isotope effect (KIE) in the presence of ions, where k_H/k_D=4.6 (at I = 0.0023), and 3.4 (in the presence of 0.5M K⁺), 3.3 (at 1.0M Na⁺), 3.9 (at 0.001M Ca²⁺), and 3.9 (at 0.001M Mg²⁺), respectively; c) the isotope effects on Arrhenius pre‐factor where A_H/A_D=0.97 (0.15) in absence of ions, and 2.29 (0.60) (at 0.5M Na⁺), 1.77 (0.29) (at 1.0M Na⁺), 1.61 (0.25) (at 0.5M K⁺), 0.42 (0.16) (at 0.001M Ca²⁺) and 0.16 (0.19) (at 0.001M Mg²⁺); d) isotope differences in the enthalpies of activation in H₂O and in D₂O, where ΔΔH^?(D,H)=3.9 (0.4) kJ mol^?1 in the absence of cations, 1.3 (0.6) at 0.5M Na⁺, 1.8 (0.4) at 0.5M K⁺, 1.5 (0.4) at 1.0M Na⁺, 5.5 (0.9) (at 0.001M Ca²⁺), and 7.9 (2.8) (at 0.001M Mg²⁺) kJ mol^?1; e) nonlinear proton inventory in reaction. In the H₂O/dioxane 1 : 1, the observed KIE is 7.8 and 4.4 in the absence and in the presence of 0.1M K⁺, respectively, and A_H/A_D=0.14 (0.03). The changes when cations are present in the reaction are explained in terms of termolecular encounter complex consisting of redox partners, and the cation where the cation can be found in a near proximity of the reaction‐activated complex thus influencing the proton/electron double tunneling event in the PCET process. A molecule of H₂O is involved in the transition state. The resulting ‘configuration’ is more ‘rigid’ and more appropriate for efficient tunneling with Na⁺ or K⁺ (extensive tunneling observed), i.e., there is more precise organized H transfer coordinate than in the case of Ca²⁺ and Mg²⁺ (moderate tunneling observed) in the reaction.     

A study of N2O decomposition rate constant at high temperature: Application to the reduction of nitrous oxide by hydrogen

Atomic resonance absorption spectroscopy has been used to investigate the thermal decomposition of N₂O by monitoring the formation of O atoms behind reflected shock waves in the temperature range 1490–2490 K and at total pressures from 58 to 347 kPa, by using the mixtures of N₂O highly diluted in Ar. For the chosen experimental conditions, the rate coefficient k_1,0 for the reaction N₂O + Ar → N₂ + O + Ar had the greatest effect on the O atom concentration increase, so this reaction rate constant could be deduced by comparison between experiment and computed simulation. In the actual temperature range, we found k_1,0 (cm³ mol^?1s^?1) = 7.2 × 10¹⁴ exp(?28878/T(K)), with an overall uncertainty evaluated to be less than 20%, by considering all the parameters, which contributed to uncertainties in the rate constant determination. The possible absorption at the O triplet emission line of N₂O has been investigated. The absorption cross section of N₂O at the O line has been estimated and taken into account for the determination of k_1,0 at high concentrations of N₂O and at temperatures lower than 1850 K. The effect of the presence of impurities like H₂O on rate constant determination has been examined and was found to be negligible. The choice of the rate coefficient for the consumption of O atoms by reaction with N₂O and that of the high‐pressure limiting rate coefficients k_1,∞ were also discussed. The rate constant reported in the present study was compared with the literature values and was found to be overall higher than those determined experimentally by other teams in the last decade. Finally, the effect of the modified constant value on reaction rate of diluted Ar–N₂O mixtures and H₂–N₂O–Ar systems was investigated. In the temperature range 1500–2500 K, the use of the rate constant deduced from this study has led to a better prediction of N₂O decomposition and N₂O reduction by H₂ than with lower rate constants proposed in the literature. © 2009 Wiley Periodicals, Inc. Int J Chem Kinet 41: 357–375, 2009     

Atmospheric chemistry of CH2FOCH2F: Reaction with Cl atoms and atmospheric fate of CH2FOCHFO· radicals

Smog chamber/FTIR techniques were used to study the Cl atom initiated oxidation of CH₂FOCH₂F in 700 Torr of N₂/O₂ at 296 K. Relative rate techniques were used to measure k(Cl + CH₂FOCH₂F) = (4.6 ± 0.7) × 10^?13 and k(Cl + CH₂FOC(O)F) = (2.9 ± 0.8) × 10^?15 (in units of cm³ molecule^?1 s^?1). Three competing fates for alkoxy radical CH₂FOCHFO· formed in the self‐reaction of the corresponding peroxy radicals were identified. In 1 atm of air at 296 K, 48 ± 3% of CH₂FOCHFO· radicals decompose via C? O bond scission, 21 ± 4% react with O₂, and 31 ± 4% undergo hydrogen atom elimination. Chemical activation effects were observed for CH₂FOCHFO· radicals formed in the CH₂FOCHFOO· + NO reaction. Infrared spectra of CH₂FOC(O)F and FC(O)OC(O)F, which are produced during the Cl atom initiated oxidation of CH₂FOCH₂F, are presented. © 2002 Wiley Periodicals, Inc. Int J Chem Kinet 34: 139–147, 2002; DOI 10.1002/kin.10038     

Cs2.91Na1.34Fe3+0.25[Fe3O(SO4)6(H2O)3]·5H2O,a member of the Maus's salt family

The title compound, tricaesium sodium iron(III) μ₃‐oxido‐hexa‐μ₂‐sulfato‐tris[aquairon(III)] pentahydrate, Cs_2.91Na_1.34Fe³⁺_0.25[Fe₃O(SO₄)₆(H₂O)₃]·5H₂O, belongs to the family of Maus's salts, K₅[Fe₃O(SO₄)₆(H₂O)₃]·6H₂O, which is based on the triaqua‐μ₃‐oxido‐hexa‐μ‐sulfato‐triferrate(III) anion, [Fe₃O(SO₄)₆(H₂O)₃]⁵⁻, with Fe in a characteristically distorted octahedral coordination environment, sharing a common corner via an oxide O atom. Cs in four different cation sites, Na in three different cation sites and five water molecules link the anions in three dimensions and set up a crystal structure in which those parts parallel to (001) and within 0.05 < z < 0.95 have a distinct trigonal pseudosymmetry, whereas the cation arrangement and bonding near z∼ 0 generate a clear‐cut noncentrosymmetric polar edifice with the monoclinic space group C2. The structure shows some cation disorder in the region near z ∼ , where one Na atom in octahedral coordination is partly substituted by Fe³⁺, and a Cs atom is substituted by small amounts of Na on a separate nearby site. One Na atom, located on a twofold axis at z = 0 and tetrahedrally coordinated by four sulfate O atoms of two [Fe₃O(SO₄)₆(H₂O)₃]⁵⁻ units, plays a key role in generating the noncentrosymmetric structure. Three of the seven different cation sites are on twofold axes (one Na⁺ site and two Cs⁺ sites), and all other atoms of the structure are in general positions.     

Study of the reactions of oxygen atoms with carbonothioicdichloride,carbonothioicdifluoride, and tetrafluoro-1,3-dithietane

The reactions of ground-state oxygen atoms with carbonothioicdichloride, carbonothioicdifluoride, and tetrafluoro-1,3-dithietane have been studied in a crossed molecular jet reactor in order to determine the initial reaction products and in a fast-flow reactor in order to determine their overall rate constants at temperatures between 250 and 500 K. These rate constants are??(O + C₂CS) =(3.09 ± 0.54) × 10^?11 exp(+115 ± 106 cal/mol/RT),??(O + F₂CS) = (1.22 ± 0.19) × 10^?11 exp(-747 ± 95 cal/mol/RT), and??(O + F₄C₂S₂) = (2.36 ± 0.52) × 10^?11 exp(-1700 ± 128 cal/mol/RT) cm³/molec˙sec. The detected reaction products and their rate constants indicate that the primary reaction mechanism is the electrophilic addition of the oxygen atom to the sulfur atom contained in the reactant molecule to form an energy-rich adduct which then decomposes by C-S bond cleavage.