Chlorthionitrenkomplexe des Molybdäns

Chlorothionitrene Complexes of Molybdenum Molybdenum pentachloride reacts with trimer thiazylchloride, (NSCl)₃, forming the chlorothionitrene complex \documentclass{article}\pagestyle{empty}\begin{document}$ {\rm Cl}_4 {\rm Mo} = \mathop {\rm N}\limits^ \oplus = \mathop {{\rm SCl}}\limits^ \ominus $\end{document}, in which the chlorothionitrene ligand is to be understood as (NSCl)^2? group. I reacts with phosphorylchloride forming the solvate Cl₃PO? Mo(Cl₄)(NSCl) ( II ) that can also be obtained directly from MoCl₅ · OPCl₃ and trithiazylchloride. II reacts with chloride ions giving the anionic chlorothionitrene complex [Cl₅Mo(NSCl)]? ( III ). Thermal decomposition of I leads to MoNCl₃ under SCl₂ cleavage, while reaction of I with chloride ions gives [MoNCl₄]?. Both reactions prove chlorothionitrene complexes to be excellent precursors for the syntheses of nitrido complexes. The complexes I—III have been characterized by IR spectroscopy.     

Structures and relative energies of gas-phase [C2H7N]+˙ radical cations

Ab initio molecular orbital calculations with split-valence plus polarization basis sets and incorporating electron correlation and zero-point energy corrections have been used to examine possible equilibrium structures on the [C₂H₇N]⁺˙ surface. In addition to the radical cations of ethylamine and dimethylamine, three other isomers were found which have comparable energy, but which have no stable neutral counterparts. These are \documentclass{article}\pagestyle{empty}\begin{document}$ \mathop {\rm C}\limits^{\rm .} {\rm H}_{\rm 2} {\rm CH}_{\rm 2} \mathop {\rm N}\limits^{\rm + } {\rm H}_{\rm 3} $\end{document}, \documentclass{article}\pagestyle{empty}\begin{document}$ {\rm CH}_{\rm 3} \mathop {\rm C}\limits^{\rm .} {\rm H}\mathop {\rm N}\limits^{\rm + } {\rm H}_{\rm 3} $\end{document}and\documentclass{article}\pagestyle{empty}\begin{document}$ {\rm CH}_{\rm 3} \mathop {\rm N}\limits^{\rm + } {\rm H}_{\rm 2} \mathop {\rm C}\limits^. {\rm H}_{\rm 2} {\rm }, $\end{document} with calculated energies relative to the ethylamine radical cation of ?33, ?28 and 4 kJ mol^?1, respectively. Substantial barriers for rearrangement among the various isomers and significant binding energies with respect to possible fragmentation products are found. The predictions for \documentclass{article}\pagestyle{empty}\begin{document}$ \mathop {\rm C}\limits^. {\rm H}_{\rm 2} {\rm CH}_{\rm 2} \mathop {\rm N}\limits^ + {\rm H}_{\rm 3} $\end{document} and \documentclass{article}\pagestyle{empty}\begin{document}$ {\rm CH}_{\rm 3} \mathop {\rm C}\limits^{\rm .} {\rm H}\mathop {\rm N}\limits^{\rm + } {\rm H}_{\rm 3}$\end{document} are consistent with their recent observation in the gas phase. The remaining isomer, \documentclass{article}\pagestyle{empty}\begin{document}$ {\rm CH}_{\rm 3} \mathop {\rm N}\limits^{\rm + } {\rm H}_{\rm 2} \mathop {\rm C}\limits^{\rm .} {\rm H}_{\rm 2} {\rm },$\end{document}is also predicted to be experimentally observable.     

The formation of [CH3CH2C(OH)CH2]+˙ from 1-hepten-3-ol

The [C₄H₈O]^+˙ ion in the mass spectrum of 1-hepten-3-ol is shown to be \documentclass{article}\pagestyle{empty}\begin{document}$ {\rm{CH}}_{\rm{3}} {\rm{CH}}_{\rm{2}} {\rm{C(= }}\mathop {\rm{O}}\limits^{\rm{ + }} {\rm{H}})\mathop {\rm{C}}\limits^{\rm{.}} {\rm{H}}_{\rm{2}} $\end{document} by collisional activation spectra, appearance energies and comparison of the ratios of the intensities of metastable decompositions. [C₄H₈O]^+˙ appears to be formed by rearrangement of ionized 1-hepten-3-ol to \documentclass{article}\pagestyle{empty}\begin{document}$ {\rm{CH}}_{\rm{3}} \mathop {\rm{C}}\limits^{\rm{.}} {\rm{HC(= }}\mathop {\rm{O}}\limits^{\rm{ + }} {\rm{H)CH}}_{\rm{2}} {\rm{CH}}_{\rm{2}} {\rm{CH}}_{\rm{2}} {\rm{CH}}_{\rm{3}} $\end{document} followed by γ-hydrogen rearrangement-β-cleavage.     

Pyrolysis of dimethyl peroxide

By using isobutane (t-BuH) as a radical trapit has been possible to study the initial step in the decomposition of dimethyl peroxide (DMP) over the temperature range of 110–140°C in a static system. For low concentrations of DMP (2.5 × 10^?5?10^?4M) and high pressures of t?BuH (～0.9 atm) the first-order homogeneous rate of formation of methanol (MeOH) is a direct measure of reaction (1): \documentclass{article}\pagestyle{empty}\begin{document}${\rm DMP}\mathop \to \limits^1 2{\rm Me}\mathop {\rm O}\limits^{\rm .},{\rm Me}\mathop {\rm O}\limits^{\rm .} + t{\rm - BuH}\mathop \to \limits^4 {\rm MeOH} + t{\rm -}\mathop {\rm B}\limits^{\rm .} {\rm u}$\end{document}. For complete decomposition of DMP in t-BuH, virtually all of the DMP is converted to MeOH. Thus DMP is a clean thermal source of Me\documentclass{article}\pagestyle{empty}\begin{document}$\mathop {\rm O}\limits^{\rm .}$\end{document}. In the decomposition of pure DMP complications arise due to the H-abstraction reactions of Me\documentclass{article}\pagestyle{empty}\begin{document}$\mathop {\rm O}\limits^{\rm .}$\end{document} from DMP and the product CH₂O. The rate constant for reaction (1) is given by k₁ = 10^15.5?37.0/θ sec^?1, very similar to other dialkyl peroxides. The thermochemistry leads to the result D(MeO? OMe) = 37.6 ± 0.2 kcal/mole and /H(Me\documentclass{article}\pagestyle{empty}\begin{document}$\mathop {\rm O}\limits^{\rm .}$\end{document}) = 3.8 ± 0.2 kcal/mole. It is concluded that D(RO? OR) and D(RO? H) are unaffected by the nature of R. From ΔS and A₁, k₂ is calculated to be 10^10.3±0.5 M^?1· sec^?1: \documentclass{article}\pagestyle{empty}\begin{document}$2{\rm Me}\mathop {\rm O}\limits^{\rm .} \mathop \to \limits^2 {\rm DMP}$\end{document}. For complete reaction, trace amounts of t-BuOMe lead to the result k₂ ～ 10⁹ M^?1 ·sec^?1: \documentclass{article}\pagestyle{empty}\begin{document}$2t{\rm - Bu}\mathop \to \limits^5$\end{document} products. From the relationship k₆ = 2(k₂k_5a)^1/2 and with k_5a = 10^8.4 M^?1 · sec^?1, we arrive at the result k₆ = 10^9.7 M^?1 · sec^?1: \documentclass{article}\pagestyle{empty}\begin{document}$2t{\rm - u}\mathop {\rm B}\limits^{\rm .} \to (t{\rm - Bu)}_{\rm 2}{\rm,}t{\rm -}\mathop {\rm B}\limits^{\rm .} {\rm u} + {\rm Me}\mathop {\rm O}\limits^{\rm .} \mathop \to \limits^6 t{\rm - BuOMe}$\end{document}.     

Stable [C2H7O2]+ isomers: Experimental and theoretical evidence for the existence of protonated peroxides and proton-bound dimers in the gas phase

Evidence is presented for the gas phase generation of at least eight stable isomeric [C₂H₇O₂]⁺ ions. These include energy-rich protonated peroxides (ions \documentclass{article}\pagestyle{empty}\begin{document}$ {\rm CH}_{\rm 3} {\rm CH}_2 {\rm O}\mathop {\rm O}\limits^{\rm + } {\rm H}_{\rm 2} $\end{document} (e), \documentclass{article}\pagestyle{empty}\begin{document}$ {\rm CH}_{\rm 3} {\rm CH}_{\rm 2} \mathop {\rm O}\limits^{\rm + } {\rm (H)OH} $\end{document} (f) and \documentclass{article}\pagestyle{empty}\begin{document}$ {\rm CH}_{\rm 3} {\rm O}\mathop {\rm O}\limits^{\rm + } {\rm (H)CH}_{\rm 3} {\rm (g)),} $\end{document} (g)), proton-bound dimers (ions \documentclass{article}\pagestyle{empty}\begin{document}$ {\rm CH}_{\rm 3} {\rm CH = O} \cdot \cdot \cdot \mathop {\rm H}\limits^{\rm 3} \cdot \cdot \cdot {\rm OH}_{\rm 2} $\end{document} (h) and \documentclass{article}\pagestyle{empty}\begin{document}$ {\rm CH2 = O} \cdot \cdot \cdot \mathop {\rm H}\limits^{\rm + } \cdot \cdot \cdot {\rm HOCH}_{\rm 3} $\end{document} (i)) and hydroxy-protonated species (ions \documentclass{article}\pagestyle{empty}\begin{document}$ {\rm CH}_{\rm 2} {\rm (OH)CH}_{\rm 2} \mathop {\rm O}\limits^{\rm + } {\rm H}_{\rm 2} (a), $\end{document} \documentclass{article}\pagestyle{empty}\begin{document}$ {\rm CH}_{\rm 3} {\rm CH(OH)}\mathop {\rm O}\limits^{\rm + } {\rm H}_{\rm 2} $\end{document} (b) and \documentclass{article}\pagestyle{empty}\begin{document}$ {\rm CH}_{\rm 3} {\rm OCH}_{\rm 2} \mathop {\rm O}\limits^{\rm + } {\rm H}_{\rm 2} $\end{document} (c)). The important points of the present study are (i) that these ions are prevented by high barriers from facile interconversion and (ii) that both electron-impact- and proton-induced gas phase decompositions seem to proceed via multistep reactions, some of which eventually result in the formation of proton-bound dimers.     

Nitrosylbromokomplexe des Rheniums: Re(NO)2Br3 und [Re(NO)2Br4]⊖; die Kristallstruktur von PPh4[Re(NO)2Br4] · 2 CCl4

Nitrosyl Bromo Complexes of Rhenium: Re(NO)₂Br₃ and [Re(NO)₂Br₄]^?; Crystal Structure of PPh₄[Re(NO)₂Br₄] · 2 CCl₄ PPh₄[Re(NO)₂Br₄] is prepared in the form of dark red-brown powder by the reaction of PPh₄[Re(NO)₂Cl₄] with excess boron tribromide. From a solution of CH₂Br₂ and CCl₄ it crystallizes with two moles CCl₄, one of which splits off easily in vacuo. The reaction of aluminum tribromide in CH₂Br₂ solution leads to a slightly soluble red-brown Re(NO)₂Br₃ powder. The i.r. spectra indicate cis positions of the covalently bound NO ligands in both complexes. Re(NO)₂Br₃ is dimeric via bromo bridges. The crystal structure determination of PPh₄[Re(NO)₂Br₄] · 2 CCl₄ was solved by X-ray diffraction methods at ? 115°C. The complex crystallizes in the monoclinic space group P2₁/c with four formula units per unit cell (4434 independent reflexions, R = 0.085). The unit cell dimensions are a = 1 092.3 pm, b = 2088.0 pm, c = 1 657.6 pm, β = 96.10°. The structure consists of P(C₆H₅)₄^? cations, [Re(NO)₂Br₄]^? anions and intercalated CCl₄ molecules. In the anion the NO groups are covalently bound to the Re atom like \documentclass{article}\pagestyle{empty}\begin{document}$ \mathop {{\rm RE}}\limits^ \ominus = \mathop {\rm N}\limits^ \oplus = {\rm O} $\end{document} and they are arranged in cis position to one another.     

Gas phase ion chemistry of methyl acetate,methyl propanoate and their enolic tautomers. An experimental approach

From a combination of isotopic substitution, time-resolved measurements and sequential collision experiments, it was proposed that whereas ionized methyl acetate prior to fragmentation rearranges largely into \documentclass{article}\pagestyle{empty}\begin{document}$ {\rm CH}_3 \mathop {\rm C}\limits^ + ({\rm OH}){\rm O}\mathop {\rm C}\limits^{\rm .} {\rm H}_2 $\end{document}, in contrast, methyl propanoate molecular ions isomerize into \documentclass{article}\pagestyle{empty}\begin{document}$ \mathop {\rm C}\limits^. {\rm H}_2 {\rm CH}_2 \mathop {\rm C}\limits^ + ({\rm OH}){\rm OCH}_3 $\end{document}. Metastably fragmenting methyl acetate molecular ions are known predominantly to form H₂?OH together with \documentclass{article}\pagestyle{empty}\begin{document}$ {\rm CH}_3 - \mathop {\rm C}\limits^ + = {\rm O} $\end{document}, whereas ionized methyl propanoate largely yields H₃CO˙ together with \documentclass{article}\pagestyle{empty}\begin{document}$ {\rm CH}_3 {\rm CH}_2 - \mathop {\rm C}\limits^ + = {\rm O} $\end{document}. The observations were explained in terms of the participation of different distonic molecular ions. The enol form of ionized methyl acetate generates substantially more H₃CO˙ in admixture with H₂?OH than the keto tautomer. This is ascribed to the rearrangement of the enol ion to the keto form being partially rate determining, which results in a wider range of internal energies among metastably fragmenting enol ions. Extensive ab initio calculations at a high level of theory would be required to establish detailed reaction mechanisms.     

The gas phase ion chemistry of the acetyl cation and isomeric [C2H3O]+ ions. On the structure of the [C2H3O]+ daughter ions generated from the enol of acetone radical cation

Methods are described for the unequivocal identification of the acetyl, [CH₃? \documentclass{article}\pagestyle{empty}\begin{document}$ \mathop {\rm C}\limits^{\rm + } $\end{document} ?O] (a), 1-hydroxyvinyl, [CH₂?\documentclass{article}\pagestyle{empty}\begin{document}$ \mathop {\rm C}\limits^{\rm + } $\end{document}? OH] (b), and oxiranyl, (d), cations. They involve the careful examination of metastable peak intensities and shapes and collision induced processes at very low, high and intermediate collision gas pressures. It will be shown that each [C₂H₃O]⁺ ion produces a unique metastable peak for the fragmentation [C₂H₃O]⁺ → [CH₃]⁺+CO, each appropriately relating to different [C₂H₃O]⁺ structures. [CH₃? \documentclass{article}\pagestyle{empty}\begin{document}$ \mathop {\rm C}\limits^{\rm + } $\end{document}?O] ions do not interconvert with any of the other [C₂H₃O]⁺ ions prior to loss of CO, but deuterium and ¹³C labelling experiments established that [CH₂?\documentclass{article}\pagestyle{empty}\begin{document}$ \mathop {\rm C}\limits^{\rm + } $\end{document}? OH] (b) rearranges via a 1,2-H shift into energy-rich leading to the loss of positional identity of the carbon atoms in ions (b). Fragmentation of b to [CH₃]⁺+CO has a high activation energy, c. 400 kJ mol^?1. On the other hand, , generated at its threshold from a suitable precursor molecule, does not rearrange into [CH₂?\documentclass{article}\pagestyle{empty}\begin{document}$ \mathop {\rm C}\limits^{\rm + } $\end{document}? OH], but undergoes a slow isomerization into [CH₃? \documentclass{article}\pagestyle{empty}\begin{document}$ \mathop {\rm C}\limits^{\rm + } $\end{document}?O] via [CH₂\documentclass{article}\pagestyle{empty}\begin{document}$ \mathop {\rm C}\limits^{\rm + } $\end{document}HO]. Interpretation of results rests in part upon recent ab initio calculations. The methods described in this paper permit the identification of reactions that have hitherto lain unsuspected: for example, many of the ionized molecules of type CH₃COR examined in this work produce [CH₂?\documentclass{article}\pagestyle{empty}\begin{document}$ \mathop {\rm C}\limits^{\rm + } $\end{document}? OH] ions in addition to [CH₃? \documentclass{article}\pagestyle{empty}\begin{document}$ \mathop {\rm C}\limits^{\rm + } $\end{document}?O] showing that some enolization takes place prior to fragmentation. Furthermore, ionized ethanol generates a, b and d ions. We have also applied the methods for identification of daughter ions in systems of current interest. The loss of OH^˙ from [CH₃COOD]^+˙ generates only [CH₂?\documentclass{article}\pagestyle{empty}\begin{document}$ \mathop {\rm C}\limits^{\rm + } $\end{document}? OD]. Elimination of CH₃^˙ from the enol of acetone radical cation most probably generates only [CH₃? \documentclass{article}\pagestyle{empty}\begin{document}$ \mathop {\rm C}\limits^{\rm + } $\end{document}?O] ions, confirming the earlier proposal for non-ergodic behaviour of this system. We stress, however, that until all stable isomeric species (such as [CH₃? \documentclass{article}\pagestyle{empty}\begin{document}$ \mathop {\rm O}\limits^{\rm + } $\end{document}?C:]) have been experimentally identified, the hypothesis of incompletely randomized energy should be used with reserve.     

Three new isomers of [C2H6O]+˙: The radical cations [CH3O(H)CH2]+˙, [CH3CHOH2]+˙ and a low-energy isomer of unassigned structure

Three new [C₂H₆O]⁺˙ ions have been generated in the gas phase by appropriate dissociative ionizations and characterized by means of their metastable and collisionally induced fragmentations. The heats of formation, ΔH_f⁰, of the two ions which were assigned the structures [CH₃O(H)CH₂]⁺˙ and [CH₃CHOH₂]⁺˙ could not be measured. The third isomer, to which the structure \documentclass{article}\pagestyle{empty}\begin{document}$ {\rm CH}_{\rm 2} = \mathop {\rm C}\limits^{\rm .} {\rm H} \cdot \cdot \cdot \mathop {\rm H}\limits^ + \cdot \cdot \cdot {\rm OH}_{\rm 2} $\end{document} is tentatively assigned, was measured to have ΔH_f⁰ = 732±5 kJ mol^?1, making it the [C₂H₆O]⁺˙ isomer of lowest experimental heat of formation. It was found that the exothermic ion–radical recombinations [CH₂OH]⁺+CH₃˙→[CH₃O(H)CH₂]⁺˙ and \documentclass{article}\pagestyle{empty}\begin{document}$ {\rm CH}_{\rm 3} \mathop {\rm C}\limits^{\rm + } {\rm HOH + H}^{\rm .} $\end{document}→[CH₃CHOH₂]⁺˙ have large energy barriers, 1.4 and ?0.9 eV, respectively, whereas the recombinations yielding [CH₃CH₂OH]⁺˙ have little or none.     

Zum Einfluß der Alkylsubstitution auf die Kupfer(II)-Extraktion mit 1-Alkyl-2(2-hydroxyphenyl)-Δ2-imidazolinen

The Influence of the Alkyl Substituents on Copper(II) Extraction by 1-Alkyl-2(2-hydroxyphenyl)-Δ²-imidazolines In acid solution (pH ≤ 4) 1-alkyl-2(2-hydroxyphenyl)-Δ²-imidazolines (RLH) form cations RLH₂⁺ and copper(II) chelates of the type Cu(RNNO)₂. Therefore in the course of the copper(II) extraction the addition of two ligands RLH and the elimination of four protons are expected. For systems with BuLH as an extractant this prediction is confirmed by slope-analysis (lg D_Cu vs. lg c_o,BuLH and lg D_Cu vs. pH). But in extraction systems of OcLH and DodLH, depending on the concentration of RLH, the slope of lg D_Cu vs. lg c_o,RLH is not higher than 1 or even 0. The reason is that the copper(II) extraction is preceded by the formation of the complexes \documentclass{article}\pagestyle{empty}\begin{document}$ {\rm Cu}\left[{\left({{\rm R}\mathop {\rm N}\limits^ \oplus {\rm HNOH}} \right){\rm X}^ \ominus } \right]^{2 \oplus } $\end{document} ( III ) and \documentclass{article}\pagestyle{empty}\begin{document}$ {\rm Cu}\left[{\left({{\rm R}\mathop {\rm N}\limits^ \oplus {\rm HNOH}} \right){\rm X}^ \ominus } \right]_2 ^{2 \oplus } $\end{document} ( IV ) in the aqueous phase. Among other reasons the concentration of III and IV depends on the tendency of RLH₂^⊕ to form ion pairs \documentclass{article}\pagestyle{empty}\begin{document}$ \left({{\rm R}\mathop {\rm N}\limits^ \oplus {\rm HNOH}} \right){\rm X}^ \ominus $\end{document} ( I ). This tendency increases with the length of the alkyl chains and for the anions in the order SO₄^2? ≤ NO₃^? ≤ ClO₄^?. Such quantities of III and IV which are essential for the course of the extraction are formed only with the extractants OcLH and DodLH, but not with BuLH. In general a variation of peripheric alkyl chains in metal extractants changes only the distribution coefficients of the corresponding metal chelates. But in the series BuLH, OcLH, DodLH both the distribution coefficients and the extraction process as a whole are changed. Some influence of the partial deprotonation of III and IV on the extraction curves is observed.     

Über Oxidsysteme mit Übergangsmetallionen in verschiedenen Oxydationsstufen. X. Elektronische und infrarotspektroskopische Untersuchungen am System Zn(ZnxV2−x)O4

The controlled valency semiconduction in the spinel system \documentclass{article}\pagestyle{empty}\begin{document}${\rm Zn}({\rm Zn}_{\rm x} \mathop {\rm V}\limits^{ + 3} _{2 - 2{\rm x}} \mathop {\rm V}\limits^{ + 4} _{\rm x}){\rm O}_4 (0 \le {\rm x} \le 0.50)$\end{document} is due to the controlled variation of the ratio V³⁺/V⁴⁺ at octahedral sites. The low temperature phase which is present according to X-ray patterns above x = 0.18 with an ordered cation distribution at the octahedral sites shows a higher specific electrical resistivity than the high temperature phase which is characterized by a random cation distribution. The activation energies, too, differ in the range x > 0.15. The whole region of solid solutions shows p-type conductivity. The thermo-EMF has a weak temperature dependence for x > 0.03. The IR spectra of both phases are identical in the range between 1000 and 200 cm^?1.     

The vinyloxonium cation, \documentclass{article}\pagestyle{empty}\begin{document}${\rm CH}_{\rm 2} = {\rm CH - }\mathop {\rm O}\limits^{\rm + } {\rm H}_{\rm 2}$\end{document}, a stable [C2H5O]+ species in the gas phase

The charge stripping mass spectra of [C₂H₅O]⁺ ions permit the clear identification of four distinct species: \documentclass{article}\pagestyle{empty}\begin{document}${\rm CH}_{\rm 3} - {\rm O - }\mathop {\rm C}\limits^{\rm + } {\rm H}_{\rm 2}$\end{document}, \documentclass{article}\pagestyle{empty}\begin{document}${\rm CH}_{\rm 3} - \mathop {\rm C}\limits^{\rm + } {\rm H - OH}$\end{document}, and \documentclass{article}\pagestyle{empty}\begin{document}${\rm CH}_{\rm 2} = {\rm CH - }\mathop {\rm O}\limits^{\rm + } {\rm H}_{\rm 2}$\end{document}. The latter, the vinyloxonium ion, has not been identified before. It is generated from ionized n-butanol and 1,3-propanediol. Its heat of formation is estimated to be 623±12 kJ mol^?1. The charge stripping method is more sensitive to these ion structures than conventional collisional activation, which focuses attention on singly charged fragment ions.     

Structure and formation of gaseous [C4H5O]+ ions. I—isomeric ions of the type C3H5\documentclass{article}\pagestyle{empty}\begin{document} $\mathop {\rm C}\limits^ + =\!= $\end{document}O

Characterization of [C₄H₅O]⁺ ions in the gas phase using their collisional activation spectra shows that the four C₃H₅\documentclass{article}\pagestyle{empty}\begin{document} $\mathop {\rm C}\limits^ + =\!= $\end{document}O isomers CH₂?C(CH₃)\documentclass{article}\pagestyle{empty}\begin{document} $\mathop {\rm C}\limits^ + =\!= $\end{document}O, CH₂?CHCH₂\documentclass{article}\pagestyle{empty}\begin{document} $\mathop {\rm C}\limits^ + =\!= $\end{document}O, CH₃CH?CH\documentclass{article}\pagestyle{empty}\begin{document} $\mathop {\rm C}\limits^ + =\!= $\end{document}O and ?? \documentclass{article}\pagestyle{empty}\begin{document} $\mathop {\rm C}\limits^ + =\!= $\end{document}O are stable for ≥ 10^?5 s. It is concluded further from the characteristic shapes for the unimolecular loss of CO from C₃H₅\documentclass{article}\pagestyle{empty}\begin{document} $\mathop {\rm C}\limits^ + =\!= $\end{document}O ions generated from a series of precursor molecules that the CH₂?CH(CH₃)\documentclass{article}\pagestyle{empty}\begin{document} $\mathop {\rm C}\limits^ + =\!= $\end{document}O- and CH₂?CHCH₂\documentclass{article}\pagestyle{empty}\begin{document} $\mathop {\rm C}\limits^ + =\!= $\end{document}O-type ions dissociate over different potential surfaces to yield [allyl]⁺ and [2-propenyl]⁺ [C₃H₅]⁺ product ions respectively. Cyclopropyl carbonyl-type ions lose CO with a large kinetic energy release, which points to ring opening in the transition state, whereas this loss from CH₃CH?CH\documentclass{article}\pagestyle{empty}\begin{document} $\mathop {\rm C}\limits^ + =\!= $\end{document}O-type ions is proposed to occur via a rate determining 1,2-H shift to yield 2-propenyl cations.     

The gas-phase pyrolysis of alkyl nitrites. III. Isopropyl nitrite

The rate of decomposition of isopropyl nitrite (IPN) has been studied in a static system over the temperature range of 130–160°C. For low concentrations of IPN (1–5 × 10^?5M), but with a high total pressure of CF₄ (～0.9 atm) and small extents of reaction (～1%), the first-order rates of acetaldehyde (AcH) formation are a direct measure of reaction (1), since k₃ » k₂(NO): \documentclass{article}\usepackage{amssymb}\pagestyle{empty}\begin{document}$ {\rm IPN}\begin{array}{rcl} 1 \\ {\rightleftarrows} \\ 2 \\ \end{array}i - \Pr \mathop {\rm O}\limits^. + {\rm NO},i - \Pr \mathop {\rm O}\limits^. \stackrel{3}{\longrightarrow} {\rm AcH} + {\rm Me}. $\end{document} Addition of large amounts of NO (～0.9 atm) in place of CF₄ almost completely suppressed AcH formation. Addition of large amounts of isobutane – t-BuH – (～0.9 atm) in place of CF₄ at 160°C resulted in decreasing the AcH by 25%. Thus 25% of \documentclass{article}\pagestyle{empty}\begin{document}$ i - \Pr \mathop {\rm O}\limits^{\rm .} $\end{document} were trapped by the t-BuH (4): \documentclass{article}\pagestyle{empty}\begin{document}$ i - \Pr \mathop {\rm O}\limits^. + t - {\rm BuH} \stackrel{4}{\longrightarrow} i - \Pr {\rm OH} + (t - {\rm Bu}). $\end{document} The result of adding either NO or t-BuH shows that reaction (1) is the only route for the production of AcH. The rate constant for reaction (1) is given by k₁ = 10^{16.2±0.4–41.0±0.8}/θ sec^?1. Since (E₁ + RT) and ΔH°₁ are identical, within experimental error, both may be equated with D(i-PrO-NO) = 41.6 ± 0.8 kcal/mol and E₂ = 0 ± 0.8 kcal/mol. The thermochemistry leads to the result that \documentclass{article}\pagestyle{empty}\begin{document}$ \Delta H_f^\circ (i - {\rm Pr}\mathop {\rm O}\limits^{\rm .} ) = - 11.9 \pm 0.8{\rm kcal}/{\rm mol}. $\end{document} From ΔS°₁ and A₁, k₂ is calculated to be 10^10.5±0.4M^?1·sec^?1. From an independent observation that k₆/k₂ = 0.19 ± 0.03 independent of temperature we find E₆ = 0 ± 1 kcal/mol and k₆ = 10^9.8+0.4M^?;1·sec^?1: \documentclass{article}\pagestyle{empty}\begin{document}$ i - \Pr \mathop {\rm O}\limits^. + {\rm NO} \stackrel{6}{\longrightarrow} {\rm M}_2 {\rm K} + {\rm HNO}. $\end{document} In addition to AcH, acetone (M₂K) and isopropyl alcohol (IPA) are produced in approximately equal amounts. The rate of M₂K formation is markedly affected by the ratio S/V of different reaction vessels. It is concluded that the M₂K arises as the result of a heterogeneous elimination of HNO from IPN. In a spherical reaction vessel the first-order rate of M₂K formation is given by k₅ = 10^9.4–27.0/θ sec^?1: \documentclass{article}\pagestyle{empty}\begin{document}$ {\rm IPN} \stackrel{5}{\longrightarrow} {\rm M}_2 {\rm K} + {\rm HNO}. $\end{document} IPA is thought to arise via the hydrolysis of IPN, the water being formed from HNO. This elimination process explains previous erroneous results for IPN.     

On the shift of H2O between the carbons of the radical cation [CH2CH2OH2]+˙

Computations predict that H₂O will shift rapidly between the carbons of \documentclass{article}\pagestyle{empty}\begin{document}$ \mathop {\rm C}\limits^{\rm .} {\rm H}_2 {\rm CH}_2 \mathop {\rm O}\limits^ + {\rm H}_2 $\end{document} over most of the energy range between the threshold for formation of the ion and the onset of its decomposition. This prediction is important to understanding the relationships and contrasts between the chemistries of free radicals and carbonium ions. We present experimental evidence that the theoretical predictions are correct.     

Zum Einfluß der Alkylkette auf Protolyse,Komplexbildung und Extraktionseigenschaften N-substituierter 2-(o-Hydroxyphenyl)-Δ2-imidazoline

Influence of the Alkyl Chain on Protolysis, Complex Formation, and Extraction Properties of N-Substituted 2-(Δ²-Imidazolin-2-yl)-phenols N-substituted 2-(Δ²-imidazolin-2-yl)-phenols RNNOH may be used as extractants of copper(II) from acidic solutions. In an aqueous phase they are existent as betains \documentclass{article}\pagestyle{empty}\begin{document}$ {\rm R}\mathop {\rm N}\limits^ \oplus {\rm HNO}^ \ominus $\end{document} ( IIa ). Solvents with lower dielectricity constants (dioxane-water-mixtures) favour the neutral acid RNNOH ( IIb ) a tautomer of IIa . The protonation of IIa or IIb proceeds in a weakly acidic solution. Therefore, at 3 ≤ pH ≤ 4 which is favourable for copper(II) extraction, the extractants exist as the cations [RNHNOH]⁺. The octyl compound OcNNOH from such a solution is extracted by chloroform, less effective by toluene, as an ion pair \documentclass{article}\pagestyle{empty}\begin{document}$ [{\rm Oc}\mathop {\rm N}\limits^ \oplus {\rm HNOH]X} $\end{document}. The distribution coefficient increases in the order HSO₄^? < NO₃^? < ClO₄^? which is well-known for quaternary ammonium salts. The affinity of the ion pairs, which are derived from the butyl compound BuNNOH, to organic solvents is very weak independently of the anion. For solubility reasons a study of the formation of the trans-planar copper(II) chelates Cu(RNNO)₂ is possible only in dioxane-water mixtures. Because of lg K₁ ≥ lg k₂ + 2 the stability regions of Cu(RNNO)⁺ and CU(RNNO)₂ are clearly separated. The distribution coefficients of Cu(RNNO)₂ increase with the length of R exceeding that of the free ligand by one power of ten and more.     

[C3H3O]+ ions; reacting and non-reacting configurations

Three [C₃H₃O]⁺ ion structures have been characterized. The most stable of these is \documentclass{article}\pagestyle{empty}\begin{document}$ {\rm CH}_{\rm 2} = {\rm CH} - \mathop {\rm C}\limits^ + = {\rm O} $\end{document} its heat of formation ΔH_f was measured as 749±5 kJ mol^?1. In the μs time frame this ion fragments exclusively by loss of CO, a process which also dominates its collisional activation mass spectrum. The other stable [C₃H₃O]⁺ structures, \documentclass{article}\pagestyle{empty}\begin{document}$ {\rm CH}\equiv \mathop {\rm C}\limits^ + - {\rm CHOH} $\end{document} and \documentclass{article}\pagestyle{empty}\begin{document}$ {\rm CH}_{\rm 2} = {\rm C} = \mathop {\rm C}\limits^{\rm + } - {\rm OH}, $\end{document}, were generated from some acetylenic and allenic precursor ions; their heats of formation were estimated to be 830 and 880 kJ mol^?1 respectively. The former ion was also produced by the gas phase protonation of propynal. These ions show loss of C₂H₂ and CO in both their metastable ion and collisional activation mass spectra. The broad Gaussian-type metastable peak for the loss of CO was shown to consist of two components corresponding to gragmentations having different activation energies.     

Potential energy profiles for unimolecular reactions of organic ions: [C3H8N]+ and [C3H7O]+

The unimolecular decompositions of two isomers of [C₃H₈N]⁺, \documentclass{article}\pagestyle{empty}\begin{document}$ {\rm CH}_{\rm 3} {\rm CH}_{\rm 2} {\rm CH} = \mathop {\rm N}\limits^ + {\rm H}_2 $\end{document} and \documentclass{article}\pagestyle{empty}\begin{document}$ {\rm CH}_{\rm 3} {\rm CH}_{\rm 2} \mathop {\rm N}\limits^ + {\rm H = CH}_{\rm 2} $\end{document}, are discussed in terms of the potential energy profile over which reaction may be considered to occur. The energy needed to promote slow (metastable) dissociations of either ion is found to be less than that required to cause isomerization to the other structure. This finding is supported by the observation of different decomposition pathways, different metastable peak shapes for C₂H₄ loss, the results of ²H labelling studies, and energy measurements on the two ions. The corresponding potential energy profile for decomposition of the oxygen analogues, \documentclass{article}\pagestyle{empty}\begin{document}${\rm CH}_{\rm 3} {\rm CH}_{\rm 2} {\rm CH =\!= }\mathop {\rm O}\limits^ + {\rm H} $\end{document} and \documentclass{article}\pagestyle{empty}\begin{document}$ {\rm CH}_{\rm 3} {\rm CH}_{\rm 2} \mathop {\rm O}\limits^ + {\rm = CH}_{\rm 2} $\end{document}, is compared and contrasted with that proposed for the [C₃H₈N]⁺ isomers. This analysis indicates that for the oxygen analogues, the energy needed to decompose either ion is very similar to that required to cause isomerization to the other structure. Consequently, dissociation of either ion is finely balanced with rearrangement to the other and similar reactions are observed. Detailed mechanisms are proposed for loss of H₂O and C₂H₄ from each ion and it is shown that these mechanisms are consistent with ²H and ¹³C labelling studies, the kinetic energy release associated with each decomposition channel, the relative competition between H₂O and C₂H₄ loss and energy measurements.     

Assigning structures to [C2H3O]+ ions

The problem of assigning structures to [C₂H₃O]⁺ ions produced from a wide variety of precursor molecules has been readdressed. The identification of the acetyl cation, \documentclass{article}\pagestyle{empty}\begin{document}$ {\rm{CH}}_{\rm{3}} \mathop {\rm{C}}\limits^{\rm{ + }} = {\rm{O}} $\end{document}, from metastable peak characteristics and collisional activation mass spectra appears to be straightforward. The structure \documentclass{article}\pagestyle{empty}\begin{document}$ {\rm{CH}}_{\rm{2}} = \mathop {\rm{C}}\limits^{\rm{ + }} - {\rm{OH}} $\end{document} is also known to exist as a stable ion. A third ion, whose structure may be represented as \documentclass{article}\pagestyle{empty}\begin{document}$ \mathop {\rm{C}}\limits^{\rm{ + }} {\rm{H}}_{\rm{2}} {\rm{CHO}} $\end{document} or has also been characterized.     

Structure and formation of some [C4H5O2]+ ions generated by radical losses in pseudo simple cleavage reactions

Characterization of some [C₄H₅O₂]⁺ ions in the gas phase using their collisional activation mass spectra shows that the isomeric ions \documentclass{article}\pagestyle{empty}\begin{document}$ {\rm CH}_3 {\rm OCH = CH} - \mathop {\rm C}\limits^ + {\rm = O,} $\end{document} and \documentclass{article}\pagestyle{empty}\begin{document}$ {\rm HC} \equiv {\rm C} - \mathop {{\rm C}({\rm OH}){\rm OCH}_3 }\limits^ + $\end{document} are stable for t?10^?5 s. Of these, ions of structure were generated by the site specific gas phase protonation of γ-crotonolactone with isobutane or methanol as chemical ionization reagent gases. These results and those derived from measurements on some ²H, ¹³C and ¹⁸O labelled [C₄H₅O₂]⁺ product ions, were used to study the mechanisms of unimolecular radical elimination reactions, viz. (1) loss of CH₃˙ from [trans-methyl crotonate], (2) loss of H˙ from [methyl acrylate]⁺˙, (3) loss of H˙ from [cyclopropane carboxylic acid]⁺˙ and (4) loss of CH₃˙ from [1,3-dimethoxypropyne]⁺˙. It is concluded that none of these losses occur by simple bond cleavage. Mechanisms are presented which account for the observation that the first three reactions yield product ions of structure whereas the ions generated by reaction (4) have structure \documentclass{article}\pagestyle{empty}\begin{document}$ {\rm CH}_3 {\rm OCH = CH} - \mathop {\rm C}\limits^ + {\rm = O}{\rm .} $\end{document}. It is further proposed that a minor fraction of the [M-CH₃]⁺ ions from ionized trans-methyl crotonate is generated via a rearrangement process which yields ions of structure \documentclass{article}\pagestyle{empty}\begin{document}$ {\rm CH}_3 {\rm OCH = CH} - \mathop {\rm C}\limits^ + {\rm = O}{\rm .} $\end{document}.