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  • 1
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1995 (1995), S. 429-431 
    ISSN: 0947-3440
    Keywords: Transition-metal ion chemistry ; Oxidation, gas-phase ; Catalytic reactions ; Ligand effects ; Fourier-transform ion cyclotron resonance mass spectrometry ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The catalytic potential of Fe(L)+ complexes (L = benzene, pyridine, naphthalene) with respect to oxygen transfer to alkenes in the gas phase has been investigated by using Fourier-transform ion cyclotron resonance mass spectrometry. Oxidation of Fe(L)+ by N2O leads to Fe(L)O+ with reaction efficiencies of 86% (L = benzene), 40% (L = pyridine), and 44% (L = naphthalene), respectively. While „naked“ FeO+ behaves as a powerful CC- and CH-bond activation reagent, the ligated species Fe(L)O+ are entirely unreactive in that respect. However, oxygen transfer from Fe(L)O+ to olefins occurs at the collision rate with less than 10% formation of byproducts. Indirect evidence is presented suggesting that the O-atom transfer from Fe(L)O+ to olefins does not generate ketones or aldehydes; rather, epoxide formation is brought about. The largest turnover number (nt) is obtained for the Fe(C6H6)O+/C2H 4 system with nt = 6.
    Additional Material: 1 Ill.
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  • 2
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 1998 (1998), S. 983-987 
    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.
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  • 3
    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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  • 4
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 123 (1990), S. 2069-2071 
    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.
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  • 5
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 122 (1989), S. 1803-1805 
    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.
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  • 6
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 2499-2503 
    ISSN: 0009-2940
    Keywords: Bond activation ; Oxygen atom transfer ; Iron oxenoid chemistry ; Rate constants ; Ion cyclotron resonance mass spectrometry ; Ligand effects ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The presence of a benzene ligand in Fe(C6H6)O+ (1) has a profound effect on the gas-phase reactivity of FeO+. While the latter oxide is known to act as an efficient C-H/C-C bond-activation reagent, the ligated species 1 is entirely unreactive in that respect. However, 1 serves as an excellent reagent for transferring oxygen to various olefins. In addition, it is demonstrated that the ligand substitution Fe-(C6H6)O+ + X → Fe(X)O+ + 6H6) follows two principally different pathways. For X = C6D6 and C5H5N the traditional direct substitution process with attack at the metal centre is operative. However, for X = olefins it is argued that the olefin will not initially attack the metal center; rather, the reaction commences by coordinating the olefin X to the oxygen atom of Fe6H6)O+. The resulting intermediate (6H6)Fe(OX)+ will then fall apart either to separated Fe(OX)+/6H6) or to Fe(6H6)+/OX, thus bringing about an epoxidation of the olefin rather than ketone formation.
    Additional Material: 1 Ill.
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  • 7
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 1481-1483 
    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.
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  • 8
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 125 (1992), S. 279-283 
    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.
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  • 9
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 128 (1995), S. 649-650 
    ISSN: 0009-2940
    Keywords: C-H bond activation ; Ligand effects ; Iron chemistry ; Reaction mechanisms ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The presence of a cyclopentadienyl ligand brings about a complete shift of regioselectivity in the Fe+-mediated dehydrogenation of 1,8-diphenyloctane (1). While “bare” Fe+, due to the formation of an intramolecular sandwich-like complex, activates the internal C-4/C-5 positions of the alkyl chain, this chelate effect is no longer operative in the gas-phase chemistry of Fe(C5H5)+ with 1. Labeling experiments demonstrate that the C-1/C-2 and (to a minor extent) the C-2/C-3 methylene groups are activated, and a possible origin of this remarkable ligand effect is discussed.
    Additional Material: 1 Tab.
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  • 10
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 126 (1993), S. 2353-2355 
    ISSN: 0009-2940
    Keywords: Ylides ; Distonic ions ; Neutralization-reionization mass spectrometry ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The recently described (Maier et al.[2]) title compound is not only viable in an argon matrix (10 K) but is also accessible in the gas phase. Electron impact ionization of (CH3)3CCX2NC (X = H, D) gives rise to HCNCX2+, which can be successfully neutralized in a beam experiment.
    Additional Material: 2 Ill.
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