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  • Mass spectrometry  (10)
  • Neutralization-reionization mass spectrometry  (8)
  • 1
    Electronic Resource
    Electronic Resource
    Generation of 1,3-Dithia-, 1-Selena-3-thia-, and 1,3-Diselena-2-tellurole by Neutralization-Reionization Mass Spectrometry⋆ (1998)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 1998 (1998), S. 983-987 
    Details
    ISSN: 1434-1948
    Keywords: Telluroles ; Neutralization-reionization mass spectrometry ; DFT calculations ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: 2,2-Dichloro-1,3-dichalcogena-2-telluroles of sulfur and selenium, C6H4[XTe(Cl)2Y] with X, Y = S, Se, serve as precursors to generate the cation radicals of 1,3-dichalcogena-2-telluroles C6H4[XTeY]+• as well as the corresponding neutral counterparts by means of neutralization-reionization mass spectrometry. These neutral 2-telluroles are intrinsically stable for at least 1 μs in the gas phase. The most abundant fragmentation channel at the neutral and cationic stages is due to loss of atomic tellurium to afford the corresponding benzo-1,2-dichalcogena-cyclobutenes. For the latter, partial isomerization to the related dichalcogena-ortho-quinones is indicated by the mass-spectrometric fragmentation pattern.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Mass-Spectrometric Experiments together with Electronic Structure Calculations Support the Existence of the Elusive Ammonia Oxide Molecule and Its Radical Cation (1998)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 1998 (1998), S. 1529-1538 
    Details
    ISSN: 1434-1948
    Keywords: Ab initio calculations ; Mass spectrometry ; Gas-phase chemistry ; Ammonia oxide ; Hydroxylamine ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Mass-spectrometric experiments were combined with ab initio calculations to explore the cationic and neutral [H3,N,O]⋆+/0 potential energy surfaces and relevant anionic species. The calculations predict the existence of three stable cationic and neutral [H3,N,O]⋆+/0 isomers, i.e. ammonia oxide H3NO⋆+/0 (1⋆+/0), hydroxylamine H2NOH⋆+/0 (2⋆+/0) and the imine-water complex HNOH2⋆+/0 (3⋆+/0). Hydroxylamine 2 represents the most stable isomer on the neutral surface (Erel = 0), and the metastable isomers 1 (Erel = 24.8 kcal mol-1) and 3 (Erel = 61.4 kcal mol-1) are separated by barriers of 49.5 kcal mol-1 and 64.2 kcal mol-1, respectively. Adiabatic ionization of 2 (IEa = 9.15 eV) yields 2⋆+, which is 21.4 kcal mol-1 more stable than 1⋆+ and 36.4 kcal mol-1 more stable than 3⋆+. The barriers associated with the isomerizations of the cations are 58.6 kcal mol-1 for 2⋆+ → 1⋆+ and 71.4 kcal mol-1 for 2⋆+ → 3⋆+. Collisional activation (CA) and unimolecular decomposition (MI) experiments allow for a clear distinction of 1⋆+ from 2⋆+. Besides, neutralization/reionization (NR) experiments strongly support the gas-phase existence of the long-sought neutral ammonia oxide.
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  • 3
    Electronic Resource
    Electronic Resource
    Combined Quantum Chemical and Mass Spectrometry Study of [Ge,C,H]+ and Its Neutral Counterpart (1999)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 1999 (1999), S. 1203-1210 
    Details
    ISSN: 1434-1948
    Keywords: Organogermanium ions ; Mass spectrometry ; Ab initio theory ; NBO ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The cation [Ge,C,H]+ has been generated by the electron ionisation of trichloromethylgermane. Collisional activation experiments were used to establish a Ge-C-H connectivity in this species, for which a significant fraction of the ion population was found to survive neutralisation-reionisation mass spectrometry (NRMS) experiments. Thus, the neutral counterpart [Ge,C,H]0 is stable on a microsecond timescale. Becke's 3 parameter hybrid density functional (B3LYP) was used to map the ion and neutral potential-energy surfaces, in conjunction with double-zeta and triple-zeta basis sets. The computational results obtained using the triple-zeta basis sets suggest that, for the cation, the global minimum is the high spin 3Σ GeCH+, with the first Ge-C-H excited state, 1Σ GeCH+, approximately 39 kcal mol-1 less stable. The lowest energy ion structure with H-Ge-C connectivity is bent (3A′′HGeC+,∠H-Ge-C = 126.3) and 69 kcal mol-1 less stable than the global minimum. For the neutral, a doublet (2π) with Ge-C-H connectivity is predicted to be the global minimum. The classical barrier for the neutral 1,2-hydrogen shift reaction on the doublet surface is negligible (0.1 kcal mol-1), while the smallest barrier for the cation is 13.0 kcal mol-1, corresponding to (3A′′) HGeC+ → (3Σ) GeCH+. Natural bond order analysis has been used to establish the order of the metal-carbon bond for selected states of both the neutral and the ion. Neutral and cationic isomers with Ge-C triple bonds were found to be high-energy excited states, with the metal-carbon bonds in the cation and neutral ground states of order 2.0 and 2.5, respectively. The instability of Ge-C triple bonded species is attributed to the energy required for electronic promotion in the metal in order to achieve a hybrid configuration suitable for the formation of such a bond.
    Additional Material: 5 Ill.
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  • 4
    Electronic Resource
    Electronic Resource
    A Combined Neutralization-Reionization Mass Spectrometric and Theoretical Study of Oxyallyl and Other Elusive [C3, H4, O] Neutrals (1998)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1998 (1998), S. 987-1009 
    Details
    ISSN: 1434-193X
    Keywords: Neutralization-reionization mass spectrometry ; Density functional theory ; Oxyallyl ; Ketocarbenes ; Methoxy vinylidene ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Five different anionic [C3, H4, O]·- isomers, i.e. the radical anions of acrolein, acetyl carbene, formyl methyl carbene, methoxy vinylidene, and oxyallyl are generated in an ion beam mass spectrometer and subjected to neutralization-reionization (NR) mass spectrometric experiments including neutral and ion decomposition difference (NIDD) mass spectrometry; the latter allows for the examination of the neutrals′ unimolecular reactivity. Further, the anionic, the singlet and triplet neutral, and the cationic [C3, H4, O]·-/0/·+ potential-energy surfaces are calculated at the B3LYP-6-311++G(d, p) level of theory. For some species, notably the singlet state of oxyallyl, the theoretical treatment is complemented by G2, CASSCF, and MR-CI calculations. Theory and experiment are in good agreement in that at the neutral stage (i) acrolein does not react within the μsec timescale, (ii) acetyl and formyl methyl carbenes isomerize to methyl ketene, (iii) methoxy vinylidene rearranges to methoxy acetylene, (iv) singlet 1A1 oxyallyl undergoes ring closure to cyclopropanone, and (v) triplet 3B2 oxyallyl may have a lifetime sufficient to survive a NR experiment.
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  • 5
    Electronic Resource
    Electronic Resource
    The laboratory generation of potentially interstellar cumulenes S(Cn)S (n = 2-6) and their radical cations (1990)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 123 (1990), S. 2069-2071 
    Details
    ISSN: 0009-2940
    Keywords: Interstellar chemistry ; Polycarbon disulfides ; Neutralization-reionization mass spectrometry ; Beam experiments ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The title compounds are generated and characterized in the gas phase by tandem mass spectrometry (neutralization-reionization mass spectrometry); it is demonstrated that both even and odd-numbered polycarbon disulfides S(Cn)S(n = 2-6) are stable species. The elusiveness of the even-numbered analogues (n = 2, 4, 6) in the condensed phase must be due to facile intermolecular reactions.
    Additional Material: 2 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19901231020
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  • 6
    Electronic Resource
    Electronic Resource
    On the Oxenoid Character of Alkylperoxy Anions and Their Lithium Compounds: A Combined Mass-Spectrometric and Theoretical Investigation (1997)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 130 (1997), S. 1085-1097 
    Details
    ISSN: 0009-2940
    Keywords: Mass spectrometry ; Peroxides ; Oxenoids ; Density functional theory ; Kinetic energy release ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A combined mass-spectrometric and theoretical approach has been used for an investigation of the gas-phase chemistry of two representative alkylperoxy anions. Metastable CH3OO- ions undergo unimolecular loss of molecular hydrogen and formaldehyde yielding HCO-2 and OH-, respectively. The observed reactivity is in pleasing agreement with calculations of the [C,H3,O2- and [C,H,O2]- potential-energy surfaces at the BECKE3LYP/6-311+ + G** level of theory. Upon exhaustive methylation of the α-position as in t-C4H9OO- anions, the reactivity switches completely to an elimination of (CH3)2C=CH2 giving rise to the formation of HOO-. The results obtained for the “bare” alkylperoxy anions are used for the analysis of the EI mass spectrum of (t-C4H9OOLi)12 dodecamers, which thermally decompose in the inlet system at a probe temperature of ca. 130°C. The decomposition is rationalized by a mechanism involving nucleophilic attack of one t-C4H9OOLi subunit on the oxenoid oxygen atom of a second t-C4H9OOOLi moiety. This reaction may produce t-C4H9OOOLi trioxy species as intermediates, which rapidly decompose to singlet dioxygen and t-C4H9OLi.
    Additional Material: 4 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19971300810
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  • 7
    Electronic Resource
    Electronic Resource
    CCS and S(C4)S: The laboratory generation of interstellar molecules and their radical cations (1989)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 122 (1989), S. 1803-1805 
    Details
    ISSN: 0009-2940
    Keywords: Beam experiments ; Interstellar chemistry ; Dicarbon sulfide ; Butatrienedithione ; Neutralization-reionization mass spectrometry ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The title compounds are generated and characterized in the gas phase by mass spectrometric methods (neutralization-reionization mass spectrometry), and for dicarbon sulfide the experimental results are supported by ab initio MO calculations (HF/6-31G*).
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19891220930
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  • 8
    Electronic Resource
    Electronic Resource
    Mass Spectrometric Study of [Fe,C3,H6,O]+ Isomers Relevant in the Gas-phase Oxidation of Hydrocarbons by “Bare” FeO+ (1996)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 129 (1996), S. 1463-1474 
    Details
    ISSN: 0009-2940
    Keywords: Structure determination ; Mass spectrometry ; Oxidation processes ; Ion-molecule reactions ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The structures and energetics of [Fe,C3,H6,O]+ isomers are probed by mass spectrometric means. The complexes Fe-(CH3COCH3)+, Fe(CH3CH2CHO)+, Fe(CH3OCH=CH2)+, Fe(CH2O)(C2H4)+, c-(FeOCH2CH2CH2)+, Fe(CH2=CH-CH2OH)+, and Fe(OH)(C3H5)+ can be distinguished by comparing their reactivity toward benzene and their collision-induced dissociation mass spectra, respectively. These findings are used to interpret the formation of [Fe,C3,H6,O]+ in oxidation reactions of hydrocarbons by the highly reactive FeO+ cation. For example, in the reactions of FeO+ with norbornane and pentanol Fe(OH)(C3H5)+ is produced, while the reaction of FeO+ with norbornane to yield [Fe,C3,H6,O]+ is one of the rare cases of initial C—C bond activation by a “bare” transition-metal oxide. The reaction of FeO+ with propene involves formation of metalla oxetanes as primary products. In general, “bare” FeO+ is not selective and allylic C—H bond activation of propene competes efficiently, thus pointing to a potentially rich chemistry.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19961291211
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  • 9
    Electronic Resource
    Electronic Resource
    On the Generation of Polycarbon Nitride Radicals CnN. (n = 2-5) by Neutralization-Reionization Mass Spectrometry (1991)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 1481-1483 
    Details
    ISSN: 0009-2940
    Keywords: Interstellar chemistry ; Polycarbon nitride radicals ; Neutralization-reionization mass spectrometry ; Tandem mass spectrometry ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The title radicals, thought to be of prime importance in the genesis of interstellar organic molecules, are accessible in the gas phase by neutralization of the corresponding CnN+ ions (n = 2-5) using tandem mass spectrometry methods (neutralization-reionization mass spectrometry). Collision-induced dissociation reactions of mass-selected CnN+ are in keeping with the connectivity of a “carbon rod” bearing a nitrogen atom at one terminus.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19911240625
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  • 10
    Electronic Resource
    Electronic Resource
    A Mass-Spectrometric Investigation of CxNO2 (x=1, 2) Ions and Neutrals (1992)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 125 (1992), S. 279-283 
    Details
    ISSN: 0009-2940
    Keywords: Interstellar chemistry ; Heterocumulenes ; Neutralization-reionization mass spectrometry ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The isomeric [C2,N,O2]+ ions OCNCO+, OCCNO+, and NCCO2- have been generated and structurally characterized on the basis of their collisional activation, charge reversal, and neutralization-reionization mass spectra. The open-shell neutrals formed in the neutralization step undergo facile unimolecular decomposition. A recovery signal is obtained only for OCCNO.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19921250144
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