High-resolution UV photoelectron spectroscopy of diatomic halogens

Diatomic halogens are studied with UV photoelectron spectroscopy using new techniques to preserve high resolution even for reactive species. For the first time vibrational structure is observed on the ²Π_u,i (i = ^1/2,^3/2) states (F₂⁺, Cl₂⁺), the ²Σ_g⁺ states (F₂⁺, Cl₂⁺) and the Br₂⁺ (²Π_{u,$\text{3}\text{2}$}) state. On the ²Π_u,i states (F₂⁺, Cl₂⁺, Br₂⁺) spin-orbit splitting is resolved. Indications for a small potential barrier on the F₂⁺ (²Π_u,i) state for large internuclear distances are found. A new value for the spin-orbit splitting of the Cl₂⁺(²Π_g) state is presented (= ?725 cm^?1). The complementary nature of optical emission and photoelectron spectroscopy for small ions is demonstrated leading to a more complete picture of the F₂⁺ (²Π_u,i) and Cl₂⁺ (²Π_u,i) ionic states.     

Effect of inorganic anions on the titanium dioxide-based photocatalytic oxidation of aqueous ammonia and nitrite

In this study, we investigated the effects of four inorganic anions (Cl⁻, SO₄²⁻, H₂PO₄⁻/HPO₄²⁻, and HCO₃⁻/CO₃²⁻) on titanium dioxide (TiO₂)-based photocatalytic oxidation of aqueous ammonia (NH₄⁺/NH₃) at pH ∼ 9 and ∼10 and nitrite (NO₂⁻) over the pH range of 4–11. The initial rates of NH₄⁺/NH₃ and NO₂⁻ photocatalytic oxidation are dependent on both the pH and the anion species. Our results indicate that, except for CO₃²⁻, which decreased the homogeneous oxidation rate of NH₄⁺/NH₃ by UV-illuminated hydrogen peroxide, OH scavenging by anions and/or direct oxidation of NH₄⁺/NH₃ and NO₂⁻ by anion radicals did not affect rates of TiO₂ photocatalytic oxidation. While HPO₄²⁻ enhanced NH₄⁺/NH₃ photocatalytic oxidation at pH ∼ 9 and ∼10, H₂PO₄⁻/HPO₄²⁻ inhibited NO₂⁻ oxidation at low to neutral pH values. The presence of Cl⁻, SO₄²⁻, and HCO₃⁻ had no effect on NH₄⁺/NH₃ and NO₂⁻ photocatalytic oxidation at pH ∼ 9 and ∼10, whereas CO₃²⁻ slowed NH₄⁺/NH₃ but not NO₂⁻ photocatalytic oxidation at pH ∼ 11. Photocatalytic oxidation of NH₄⁺/NH₃ to NO₂⁻ is the rate-limiting step in the complete oxidation of NH₄⁺/NH₃ to NO₃⁻ in the presence of common wastewater anions. Therefore, in photocatalytic oxidation treatment, we should choose conditions such as alkaline pH that will maximize the NH₄⁺/NH₃ oxidation rate.     

The use of ferrocene in organometallic synthesis: A two-step preparation of cyclopentadienyliron acetonitrile and phosphine cations via photolysis of cyclopentadienyliron tricarbonyl or arene cations

UV photolysis of [CpFe^II(CO)₃]⁺ PF6₆^? (I) or [CpFe^II(η⁶-toluene)]⁺ PF₆^?? (II) in CH₃CN in the presence of 1 mole of a ligand L gives the new air sensitive, red complexes [CpFe^II(NCCH₃)₂L]⁺PF₆^? (III, L = PPh₃; IV; L = CO; VIII, L = cyclohexene; IX, L = dimethylthiophene) and the known air stable complex [CpFe^II(PMe₃)₂(NCMe)]⁺ PF₆^? (V). The last product is also obtained by photolysis in the presence of 2 or 3 moles of PMe₃. In the presence of dppe, the known complex [CpFe^II (dppe)(NCCH₃)]⁺ (XI) is obtained. Complex III reacts with CO under mild conditions to give the known complex [CpFe(NCCH₃)(PPh₃)CO]⁺ PF₆^? (X). UV photolysis of I in CH₃CN in the presence of 1-phenyl-3,4-dimethylphosphole (P) gives [CpFe^IIP₃]⁺ PF₆^? (XII); UV photolysis of II in CH₂Cl₂ in the presence of 3 moles of PMe₃ or I mole of tripod (CH₃C(CH₂Ph₂)₃) provides an easy synthesis of the known complexes [CpFe^II(PMe₃)₃]⁺ PF₆^? (VII) or [CpFe^IIη³-tripod]⁺ PF₆^t- (XIII). Since I and II are easily accessible from ferrocene, these photolytic syntheses provide access to a wide range of piano-stool cyclopentadienyliron(II) cations in a 2-step process from ferrocene.     

Luminescence Tuning of Upconversion Nanocrystals

Upconversion luminescence tuning of β‐NaYF₄ nanorods under 980 nm excitation has successfully been achieved by tridoping with Ln³⁺ ions with different electronic structures. The effects of Ce³⁺ ions on NaYF₄:Yb³⁺/Ho³⁺ as well as Gd³⁺ ions on NaYF₄:Yb³⁺/Tm³⁺(Er³⁺) have been studied in detail. By tridoping with Ce³⁺ ions, not only were unusual ⁵G₅→⁵I₇ and ⁵F₂/³K₈→⁵I₈ transitions from Ho³⁺ ions and 5d→4f transitions from Ce³⁺ ions observed in NaYF₄:Yb³⁺/Ho³⁺ nanorods, but also an increase in the intensity of ⁵F₅→⁵I₈ relative to ⁵S₂/⁵F₄→⁵I₈ with increasing Ce³⁺ concentration, which can be attributed to efficient energy transfers of ⁵I₆ (Ho)+²F_5/2 (Ce)→⁵I₇ (Ho)+²F_7/2 (Ce) and ⁵S₂/⁵F₄ (Ho)+²F_5/2 (Ce)→⁵F₅ (Ho)+²F_7/2 (Ce). Interestingly, with increasing pump power density, the luminescence of NaYF₄:Yb³⁺/Ho³⁺ nanorods is always dominated by the ⁵S₂/⁵F₄→⁵I₈ transition, whereas the luminescence of Ce³⁺‐tridoped NaYF₄:Yb³⁺/Ho³⁺ nanorods is dominated by the ⁵S₂/⁵F₄→⁵I₈ and ⁵G₅→⁵I₇ transitions in turn. These observations are discussed on the basis of a rate equation model. Furthermore, Gd³⁺‐tridoped NaYF₄:Yb³⁺/Tm³⁺(Er³⁺) nanorods can emit multicolor upconversion emissions spanning from the UV to the near‐infrared under 980 nm excitation. ⁶P_5/2→⁸S_7/2 (≈306 nm) and ⁶P_7/2→⁸S_7/2 (≈311 nm) transitions from Gd³⁺ ions were observed. In addition to the aforementioned luminescence properties, these Gd³⁺‐tridoped nanorods also exhibit paramagnetic behavior at room temperature and superparamagnetic behavior at 2 or 5 K.     

Kinetics and Mechanism of the Cerium(IV) Oxidation of Arnold's Base and the Protonation and Hydroxylation of Michler's Hydrol Blue

In aqueous H₂SO₄, Ce(IV) ion oxidizes rapidly Arnold's base((p-Me₂NC₆H₄)₂CH₂, Ar₂CH₂) to the protonated species of Michler's hydrol((p-Me₂NC₆H₄)₂CHOH, Ar₂CHOH) and Michler's hydrol blue((p-Me₂NC₆H₄)₂CH⁺, Ar₂CH⁺). With Ar₂CH₂ in excess, the rate law of the Ce(IV)-Ar₂CH₂ reaction in 0.100 M H₂SO₄ is expressed -d[Ce(IV)]/dt = k_app[Ar₂CH₂]₀[Ce(IV)] with k_app = 199 ± 8M^?1s^?1 at25°C. When the consumption of Ce(IV) ion is nearly complete, the characteristic blue color of Ar₂CH⁺ ion starts to appear; later it fades relatively slowly. The electron transfer of this reaction takes place on the nitrogen atom rather than on the methylene carbon atom. The dissociation of the binuclear complex [Ce(III)ArCHAr-Ce(III)] is responsible for the appearance of the Ar₂CH⁺ dye whereas the protonation reaction causes the dye to fade. In highly acidic solution, the rate law of the protonation reaction of Michler's hydrol blue is -d[Ar₂CH⁺]/dt = k_obs[Ar₂CH⁺] where K_obs = ((ac + 1)[H*] + bc[H⁺]²)/(a + b[H⁺]) (in HClO₄) and k_obs= ((ac + 1 + e[HSO₄^?])[H⁺] + bc[H⁺]² + d[HSO₄^?] + q[HSO₄^?]²/[H⁺])/(a + b[H⁺] + f[HSO₄^?] + g[HSO₄^?]/[H⁺]) (in H₂SO₄), and at 25°C and μ = 0.1 M, a = 0.0870 M s, b = 0.655 s, c = 0.202 M^?1s^?1, d = 0.110, e = 0.0070 M^?1, f = 0.156 s, g = 0.156 s, and q = 0.124. In highly basic solution, the rate law of the hydroxylation reaction of Michler's hydrol blue is -d[Ar₂CH⁺]/dt = k_OH[OH^?]₀[Ar₂CH⁺] with k_OH = 174 ± 1 M^?1s^?1 at 25°C and μ = 0.1 M. The protonation reaction of Michler's hydrol blue takes place predominantly via hydrolysis whereas its hydroxylation occurs predominantly via the path of direct OH attack.     

SiH+5 and the proton affinity of monosilane

Tandem mass spectrometric studies show that SiH⁺₅ is formed in bimolecular reactions of SiH₄ and NH⁺₂, C₂H⁺₃, C₂H⁺₆ and C₃H⁺₈ ions. The dependence of the reaction cross sections on ion energy indicates the formation of SiH⁺₅ from NH⁺₂, C₂H⁺₃, and C₂H⁺₆ to be exothermic reactions, while formation from C₃H⁺₈ is endothermic. Using known thermochemical data, these facts permit the assignment of 150 and 156 kcal/mole to the lower and upper limits of the proton affinity of monosilane.     

Effect of desolvation of the reactants during change in the acidity of the medium on the electrophilic hydroxylation and nitration of alkanes

The effect of the acidity of the medium on the hydroxylation and nitration of alkanes (RH) in 90–98% H₂SO₄ at 25°C is described quantitatively by a model taking account of the thermodynamic activity of the RH, H₂O, and HSO₄^- particles. It was concluded that in the transition states the reagents H₃O₂⁺HSO₄^- and NO₂⁺ HSO₄^- are present as HO⁺ and NO₂⁺ ions without the bases H–O and HSO₄^-, the alkanes are present without hydrophobic shells, and the initial reaction products are ROH₂⁺ and RNO₂H⁺.     

Assignment of the mechanism of predissociation of the ClO2 molecule by analysis of single-rotational-level lifetimes

Deconvolutions of measured absorption line profiles in the 1ⁿ₀ (n = 0 to 5) and the 3²₀ bands of the òA₂X?²B₁ electronic transition of ClO₂ reveal subnanosecond lifetimes for all rotational levels of the ²A₂ state. Observed ratios of radiationless rates from spin-doublet components identify direct spin-orbit coupling of the ²A₂ state with ²A₁ and/or ²B₁ vibronic states as a predominant predissociation mechanism. Variations of rates with ν′₁ locate an intersection of a second potential surface with that of the ²A₂ state.     

Vibrational spectra of nitrido and oxo complexes

The vibrational spectra of a number of transition-metal complexes containing terminal or bridging nitrido (N^3?) and oxo (O^2?) ligands are reported. Full assignments of fundamental modes are given for (OsO₃¹⁴N)^?, (OsO₃¹⁵N)^?, (Os¹⁴NX₄)^?, (Os¹⁵NX₄)^?, (Ru¹⁴NX₄)^?, (Os¹⁴NX₅)^2?, (Os¹⁵NX₅)^2? and (Ru¹⁴NX₅)^2? (X = Cl, Br), and also for the oxo complexes (Mo¹⁶OCl₄, (Mo¹⁸OCl₄)^?, (Mo¹⁶OCl₅)^2? and (Mo¹⁸OCl₅)^2?. Force constants have been evaluated for the four- and five-coordinate complexes. The significance of the results is discussed in terms of the metalligand bonding involved in these species.     

Quadrupole mass spectrometric study of positive ions from RF plasmas of pure CH4, CH4/H2, and CH4/Ar systems

Quadrupole mass spectrometry has been employed to characterize the ionic species in the discharges of pure CH₄, CH₄/H₂, and CH₄/Ar systems. For pure methane, the major positive ions in the discharge at low pressure (e.g., 0.15 torr) are CH ₃ ⁺ , C₂H ₃ ⁺ , CH ₂ ⁺ , C₂H ₂ ⁺ , CH ₄ ⁺ , C₂H ₄ ⁺ , and C₂H ₅ ⁺ at high pressure (e.g., 0.5 torr) the major ions are CH ₃ ⁺ , C₂H ₃ ⁺ , C₂H ₅ ⁺ , C₃H ₃ ⁺ , C H₃H ₇ ⁺ , C₄H ₇ ⁺ , C₅H ₇ ⁺ , C₆H ₅ ⁺ , and C₇H ₇ ⁺ . The relative abundances of C₁ ions decrease with increasing pressure, whereas those of higher-order ions increase with pressure. For 5% CH₄ + 95% H₂ mixture, in addition to those sampling from the pure methane plasma at the lower pressure, H _n ⁺ ions have also been detected. For 5% CH₄ +95% Ar mixture, the principal ions are CH ₃ ⁺ , CH ₂ ⁺ , CH⁺, CH ₅ ⁺ , Ar⁺, and ArH⁺; the ions containing more than two carbon atoms are negligible. In these discharges, the CH ₃ ⁺ and C₂H ₃ ⁺ are the most important positive ions in C₁ and C₂ ions, respectively. The ions detected are believed to come from the sheath between the electrode and the luminous plasma, and have high kinetic energy. An ion-molecule reaction mechanism is proposed which can well explain the observed main features of ionic products.Died June 1, 1991.     

Flash photolysis of SiBr4: the UV spectrum of SiBr2

In the flash photolysis of SiBr₄ both the absorption and the emission spectra corresponding to the B̃²Σ−X̃²Π transition of SiBr have been observed. A broad, structureless absorption band has also been detected in the 340–400 nm region which could be assigned to the hitherto unreported à ¹B₁−x̃ ¹A₁ transition of SiBr₂. The decay of both absorption spectra followed first-order kinetics yielding the pseudo-first-order rate constants: k(SiBr)=2.6 × 10⁴s⁻¹ and k(SiBr₂) = 8.9 × 10³⁻¹. Assuming that the principal reactions consuming these intermediates are SiBr+SiBr₄→Si₂Br₅ and SiBr₂+SiBr₄→ Si₂Br₆, the second-order rate constants have the values k(SiBr)= 9.7×10⁹ M⁻¹s⁻¹ and k(SiBr₂)= 3.3×10⁸M⁻¹s⁻¹.     

A flowing afterglow study of uranium tetraborohydride

Ionization-fragmentation of uranium(IV) tetraborohydride, U(BH₄)₄, by He⁺ and by N⁺/N₂⁺ yields, predominantly, U(BH₅)⁺ and U(B₂H₈)⁺, respectively. Attachment of thermal electrons yields U(BH₄)₄^? and ions of 1, 2, and 3 mass units less. Fluoride transfer with SF₆^?, BF₄^?, and UF_n^? (n = 5–7) and reactions with other small ions (O^?, O₂^?, NO₂^?, F^?, Cl^?, O₂⁺) are described.     

Quantitative chemical analysis on paper: Determination of phosphate in the presence of large quantities of other ions

Summary A rapid method has been developed for the determination of phosphate by means of filter paper impregnated with lead iodide. A sample is added to the impregnated filter paper by means of a capillary, and after irrigation to cause migration of the ions a white spot is obtained as the lead iodide is converted into the phosphate. The weight of the spot is dependent on the p_H and the quantity of phosphate present.The determination is possible in the presence of SCN^–, Cl^–, Br^–, NO₃ ^–, CO₃ ^–, I^–, IO₃ ^–, CH₃COO^–, B₄O₇ ^2–, F^–, Sb₂O₇ ^4–, K⁺, Na⁺, NH₄ ⁺, OH^–, H⁺, succinic, citric and tartaric acids. The determination is impossible in the presence of C₂O₄ ^2–, SO₄ ^2–, MoO₄ ^2–, NO₂ ^–, SO₃ ^2–, S^2–, CrO₄ ^2–, or CO₃ ^2–.The method permits the determination of 7–100g of phosphate with an accuracy of 2%.

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Zusammenfassung Ein schnelles Verfahren zur Phosphatbestimmung wird besehrieben, bei dem man sich eines mit Bleijodid imprägnierten Filterpapiers bedient. Die Probe wird mit einer Kapillare auf das Papier aufgebracht. Man erleichtert die Ionenbewegung durch geeignete Befeuchtung und erhält einen weißen Fleck infolge Umsetzung des Bleijodids in -phosphat. Das Gewicht des Fleckens hängt vom p_H und von der Phosphatmenge ab.Die Bestimmung ist möglich in Gegenwart von SCN^–, Cl^–, Br^–, NO₃ ^–, CO₃ ^–, J^–, JO₃ ^–, CH₃COO^–, B₄O₇ ^2–, F^–, Sb₂O₇ ^4–, K⁺, Na⁺, NH₄ ⁺, OH^–, H⁺, Bernsteinsäure, Zitronensäure und Weinsäure; sie ist nicht möglich bei Gegenwart von C₂O₄ ^2–, SO₄ ^2–, MoO₄ ^2–, NO₂ ^–, SO₃ ^2–, S^2–, CrO₄ ^2– oder CO₃ ^2–. 7 bis 100g Phosphat können mit einer Genauigkeit von 2% bestimmt werden.

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Résumé On a développé une méthode rapide pour le dosage des phosphates sur papier-filtre imprégné d'iodure de plomb. On dépose l'échantillon sur le papier-filtre imprégné, à l'aide d'un capillaire, et, après humidification pour provoquer la migration des ions, on obtient une tache blanche quand l'iodure de plomb est converti en phosphate. Le poids de la tache dépend du p_H et de la quantité de phosphate présent.Le dosage est possible en présence de SCN^–, Cl^–, Br^–, NO₃ ^–, CO₃ ^–, I^–, IO₃ ^–, CH₃COO^–, B₄O₇ ^2–, F^–, Sb₂O₇ ^4–, K⁺, Na⁺, NH₄ ⁺, OH^–, H⁺, et des acides succinique, citrique et tartrique. Il est impossible en présence de C₂O₄ ^2–, SO₄ ^2–, MoO₄ ^2–, NO₂ ^–, SO₃ ^2–, S^2–, CrO₄ ^2– ou CO₃ ^2–.La méthode permet le dosage de 7 à 100g de phosphate avec une précision de 2%.

     

The Reaction of Ozone with the Hydroxide Ion: Mechanistic Considerations Based on Thermokinetic and Quantum Chemical Calculations and the Role of HO4− in Superoxide Dismutation

The reaction of OH^? with O₃ eventually leads to the formation of ^.OH radicals. In the original mechanistic concept (J. Staehelin, J. Hoigné, Environ. Sci. Technol. 1982 , 16, 676–681), it was suggested that the first step occurred by O transfer: OH^?+O₃→HO₂^?+O₂ and that ^.OH was generated in the subsequent reaction(s) of HO₂^? with O₃ (the peroxone process). This mechanistic concept has now been revised on the basis of thermokinetic and quantum chemical calculations. A one‐step O transfer such as that mentioned above would require the release of O₂ in its excited singlet state (¹O₂, O₂(¹Δ_g)); this state lies 95.5 kJ mol^?1 above the triplet ground state (³O₂, O₂(³Σ_g^?)). The low experimental rate constant of 70 M ^?1 s^?1 is not incompatible with such a reaction. However, according to our calculations, the reaction of OH^? with O₃ to form an adduct (OH^?+O₃→HO₄^?; ΔG=3.5 kJ mol^?1) is a much better candidate for the rate‐determining step as compared with the significantly more endergonic O transfer (ΔG=26.7 kJ mol^?1). Hence, we favor this reaction; all the more so as numerous precedents of similar ozone adduct formation are known in the literature. Three potential decay routes of the adduct HO₄^? have been probed: HO₄^?→HO₂^?+¹O₂ is spin allowed, but markedly endergonic (ΔG=23.2 kJ mol^?1). HO₄^?→HO₂^?+³O₂ is spin forbidden (ΔG=?73.3 kJ mol^?1). The decay into radicals, HO₄^?→HO₂^.+O₂^.?, is spin allowed and less endergonic (ΔG=14.8 kJ mol^?1) than HO₄^?→HO₂^?+¹O₂. It is thus HO₄^?→HO₂^.+O₂^.? by which HO₄^? decays. It is noted that a large contribution of the reverse of this reaction, HO₂^.+O₂^.?→HO₄^?, followed by HO₄^?→HO₂^?+³O₂, now explains why the measured rate of the bimolecular decay of HO₂^. and O₂^.? into HO₂^?+O₂ (k=1×10⁸ M ^?1 s^?1) is below diffusion controlled. Because k for the process HO₄^?→HO₂^.+O₂^.? is much larger than k for the reverse of OH^?+O₃→HO₄^?, the forward reaction OH^?+O₃→HO₄^? is practically irreversible.     

Synthesis and molecular structures of dialkylselenonium methylide complexes of indium tribromide

The reaction of bromomethyl-dibromo-indium(III), Br₂InCH₂Br with dialkylselenides, R¹SeR² (R¹ = CH₃, R² = CH₂C₆H₅; R¹ = C₂H₅, R² = CH₂C₆H₅; R¹ = R² = CH₂C₆H₅) afforded the corresponding dialkylselenonium methylide complexes of indium tribromide, Br₃InCH₂SeR¹R², which were fully characterized by NMR spectroscopy and single crystal X-ray diffraction studies.     

Overlooked Formation of Carbonate Radical Anions in the Oxidation of Iron(II) by Oxygen in the Presence of Bicarbonate

Iron(II), (Fe(H₂O)₆²⁺, (Fe^II) participates in many reactions of natural and biological importance. It is critically important to understand the rates and the mechanism of Fe^II oxidation by dissolved molecular oxygen, O₂, under environmental conditions containing bicarbonate (HCO₃⁻), which exists up to millimolar concentrations. In the absence and presence of HCO₃⁻, the formation of reactive oxygen species (O₂⋅⁻, H₂O₂, and HO⋅) in Fe^II oxidation by O₂ has been suggested. In contrast, our study demonstrates for the first time the rapid generation of carbonate radical anions (CO₃⋅⁻) in the oxidation of Fe^II by O₂ in the presence of bicarbonate, HCO₃⁻. The rate of the formation of CO₃⋅⁻ may be expressed as d[CO₃⋅⁻]/dt=[Fe^II[[O₂][HCO₃⁻]². The formation of reactive species was investigated using ¹H nuclear magnetic resonance (¹H NMR) and gas chromatographic techniques. The study presented herein provides new insights into the reaction mechanism of Fe^II oxidation by O₂ in the presence of bicarbonate and highlights the importance of considering the formation of CO₃⋅⁻ in the geochemical cycling of iron and carbon.     

Potassium salts of hypodiphosphoric acid

The synthesis and crystal structures of a series of six crystalline potassium salts of hypodiphosphoric acid, H₄P₂O₆, are reported, namely potassium hydrogen phosphonophosphonate, K⁺·H₃P₂O₆⁻, (I), dipotassium dihydrogen hypodiphosphate monohydrate, 2K⁺·H₂P₂O₆²⁻·H₂O, (II), dipotassium dihydrogen hypodiphosphate dihydrate, 2K⁺·H₂P₂O₆²⁻·2H₂O, (III), pentapotassium hydrogen hypodiphosphate dihydrogen hypodiphosphate dihydrate, 5K⁺·HP₂O₆³⁻·H₂P₂O₆²⁻·2H₂O, (IV), tripotassium hydrogen hypodiphosphate tetrahydrate, 3K⁺·HP₂O₆³⁻·4H₂O, (V), and tetrapotassium hypodiphosphate tetrahydrate, 4K⁺·P₂O₆⁴⁻·4H₂O, (VI). All the hypodiphosphate anions, viz. H₃P₂O₆⁻, H₂P₂O₆²⁻, HP₂O₆³⁻ and P₂O₆⁴⁻, adopt a staggered conformation. The P—P bond lengths [2.1722 (7)–2.1892 (10) Å] do not depend on the basicity of the anion. The compounds are organized into different types of one‐, two‐ or three‐dimensional polymeric hydrogen‐bonded networks, or simply exist in the form of isolated or dimeric units. The coordination numbers of the K⁺ cations range from 6 to 9, and the cationic sublattices are polymeric one‐, two‐ or three‐dimensional networks, or isolated [KO₆] or dimeric [K₂O₁₂] polyhedra.     

Stability constants of iron(III)-8-hydroxyquinoline complexes

Spectrophotometric determination of the formation constants of iron(III)-8-hydroxyquinoline complexes in 0.1 M sodium perchlorate solution at 25° gave the values K₁=[FeOx²⁺]/([Fe³⁺][Ox^-])=4.9·10¹³, K₂=[FeOx₂⁺]/([FeOx²⁺][Ox^-])=4.2·10¹² and K₃=[FeOx₃]/([FeOx₂⁺][Ox^-])=3.9·10¹⁰. FeOx₂OH and FeOx(OH)₂ are obtainable as solid phases. FeOx₃ (K_sp=3·10^-44, intrinsic solubility 1.6·10^-7 M) dissolves in basic solutions to form FeOx₂(OH)₂ -In a solution saturated with FeOx³, ([FeOx₂(OH)₂^-][Ox^-])/[OH^-]²=7.7·10^-5.     

UV absorption spectrum of CF3CFClO2 and kinetics of the self reaction of CF3CFCl and CF3CFClO2 and the reactions of CF3CFClO2 with NO and NO2

The ultraviolet absorption spectrum of CF₃CFClO₂ and the kinetics of the self reactions of CF₃CFCl and CF₃CFClO₂ radicals and the reactions of CF₃CFClO₂ with NO and NO₂ have been studied in the gas phase at 295 K by pulse radiolysis/transient UV absorption spectroscopy. The UV absorption cross section of CF₃CFCl radicals was measured to be (1.78 ± 0.22) × 10^?18 cm² molecule^?1 at 220 nm. The UV spectrum of CF₃CFClO₂ radicals was quantified from 220 nm to 290 nm. The absorption cross section at 250 nm was determined to be (1.67 ± 0.21) × 10^?18 cm² molecule^?1. The rate constants for the self reactions of CF₃CFCl and CF₃CFClO₂ radicals were (2.6 ± 0.4) × 10^?12 cm³ molecule^?1 s^?1 and (2.6 ± 0.5) × 10^?12 cm³ molecule^?1 s^?1, respectively. The reactivity of CF₃CFClO₂ radicals towards NO and NO₂ was determined to (1.5 ± 0.6) × 10^?11 cm³ molecule^?1 s^?1 and (5.9 ± 0.5) × 10^?12 cm³ molecule^?1 s^?1, respectively. Finally, the rate constant for the reaction of F atoms with CF₃CFClH was determined to (8 ± 2) × 10^?13 cm³ molecule^?1 s^?1. Results are discussed in the context of the atmospheric chemistry of HCFC-124, CF₃CFClH. © 1994 John Wiley & Sons, Inc.     

Mass spectra of sulfinamide derivatives and identification of their thermal decomposition products

The mass spectra of 30 sulfinamide derivatives (RSONHR', R' alkyl or p-XC₆H₄) are reported. Most of the spectra had peaks attributable to thermal decomposition products. For some compounds these were identified by pyrolysis under similar conditions to be: RSO₂NHR', RSO₂SR, RSSR and NH₂R' (in all kinds of sulfinyl amides); RSNHR' (in the case of arylsulfinyl arylamides); RSO₂C₆H₄NH₂, RSOC₆H₄NH₂ and RSC₆H₄NH₂ (in the case of arylsulfinyl arylamides of the type of X = H) The mass spectra of the three thermally stable compounds showed that there are several kinds of common fragment ions. The mass spectra of the thermally labile compounds had two groups of ions; (i) characteristic fragment ions of the intact molecules and (ii) the molecular ions of the thermal decomposition products. It was concluded that the sulfinamides give the following ions after electron impact: [M]⁺, [M ? R]⁺, [M ? R + H]⁺, [M ? SO]⁺, [RS]⁺, [NHR']⁺, [NHR' + H]⁺, [RSO]⁺, [RSO + H]⁺, [R]⁺, [R + H]⁺, [R']⁺ and [M ? OH]⁺, and that the thermal decomposition products give the following ions: [RSO₂SR]⁺, [RSSR]⁺, [M ? O]⁺, [M + O]⁺ and [RSOC₆H₄NH₂]⁺.