Bare Transition-metal Ions Research Articles

Gas-phase chemistry of bare transition-metal ions in comparison. 2. Reactions of titanium(+) to zinc(+) with 2-ethylbutanenitrile

Gas-phase chemistry of bare transition-metal ions in comparison. 2. Reactions of titanium(+) to zinc(+) with 2-ethylbutanenitrile

Ionization energies of the cations of metallocene (M(C 5H 5) +2), their half-sandwich complexes MC 5H +5 and the bare transition-metal ions M + (M = Fe, Co, Ni)

Charge stripping experiments indicate that in the reaction M + → M 2 + e − the doublycharged transition-metal ions M 2+ (M = Fe, Co, Ni) are formed in excited states. Introduction of one or two C 5H 5 ligands drastically reduces the Q min values of the reaction M(C 5H 5) + x → M(C 5H 5) 2+) x + e − (x = 1, 2) by at least 3.5 eV. The experimental findings support existing molecular orbital concepts of metallocene compounds.

Specific Activation of CH‐ and CC‐Bonds by Bare Transition‐Metal Ions

AbstractChemists are continuously facing questions and problems as follows: Is it possible to direct the course of a reaction according to one's intentions? Is the activation of specific bonds that are either remote or adjacent to a functional group feasible? What factors dictate the different behaviour of transition‐metal ions in their reactions with organic substrates? Answers to these and other questions are provided by studying the gas‐phase chemistry of “naked” first‐row transition‐metal ions with aliphatic nitriles and some other simple organic substrates. By systematically modifying both the organic molecules and the metal ions, a quite detailed insight is achieved into the mechanisms that are operative, and knowledge is accumulated which permits to specify the conditions that are to be met in order to bring about specific processes. “Remote functionalization”, the generation of ion/dipole intermediates, and the formation of multi‐ligated metal‐ion alkene complexes turn out to be the most important mechanisms in the reactions of aliphatic nitriles with transition‐metal ions in the gas phase. In addition, results will be presented which point to degenerate isomerizations involving metallacycles as intermediates. We will also demonstrate that direct CC bond activation prior to CH bond activation can be achieved, a process for which no analogue exists in solution chemistry. The studies have been performed by using tandem mass spectrometry techniques in a sector‐field mass spectrometer as well as ion/molecule reactions in a Fourier transform ion cyclotron resonance (FTICR) instrument.

Evidence for the activation of unstrained carbon-carbon bonds by bare transition metal ions M+ (M = Fe, Co) without prior C-H bond activation

The metastable ion (MI) decompositions of RNH 2 /M + complexes (R = (C 2 H 5 ) 2 CHCH 2 , C 2 H 5 C(CH 3 ) 2 CH 2 ; M=Fe, Co) in the gas phase have been studied by tandem mass spectrometry with a four-sector instrument of BEBE configuration. The analyses of the MI spectra of isotopically labeled complexes uncover processes which inter alia demonstrate that the loss of C 4 H 8 corresponds to a reaction in which site-specific oxidative addition of an unstrained C-C bond to the «anchored» transition-metal ion M + takes place without prior C-H bond activation. The intramolecular methyl migration preceding the elimination of C 4 H 8 is subject to a secondary kinetic isotope effect of k H /k D = 1.33 for M + = Fe + and k H /k D = 1.15 for M + = Co + per D atom. Additional processes observed correspond to the generation of molecular hydrogen, methane, ethylene and ethane. All reactions are highly specific, and mechanisms are suggested that are in keeping with the labeling data

Gas-phase chemistry of bare transition-metal ions in comparison

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTGas-phase chemistry of bare transition-metal ions in comparisonKarsten Eller, Waltraud Zummack, and Helmut SchwarzCite this: J. Am. Chem. Soc. 1990, 112, 2, 621–627Publication Date (Print):January 1, 1990Publication History Published online1 May 2002Published inissue 1 January 1990https://doi.org/10.1021/ja00158a019RIGHTS & PERMISSIONSArticle Views207Altmetric-Citations153LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (842 KB) Get e-Alerts Get e-Alerts

Reactions of bare transition-metal ions M+ (M = iron, cobalt) with 1-alkanols in the gas phase

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTReactions of bare transition-metal ions M+ (M = iron, cobalt) with 1-alkanols in the gas phaseTilmann. Pruesse and Helmut. SchwarzCite this: Organometallics 1989, 8, 12, 2856–2860Publication Date (Print):December 1, 1989Publication History Published online1 May 2002Published inissue 1 December 1989https://doi.org/10.1021/om00114a020RIGHTS & PERMISSIONSArticle Views52Altmetric-Citations34LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (580 KB) Get e-Alerts Get e-Alerts

Remote functionalization of C-H and C-C bonds by "naked" transition-metal ions (Cosi Fan Tutte)

Gas-phase experiments with naked transition-metal ions offer a unique opportunity to probe, in the absence of any solvation, ion-pairing, and/or ligand effects, the intrinsic properties of reactive organometallic species and to evaluate the potential role these remarkable transients play in the initial steps of the activation of C-H and C-C bonds. Not surprisingly, this topic is of fundamental interest in catalysis and has attracted considerable attention in the last decade. The authors and later others, have recently demonstrated that remote functionalization can be achieved in the gas phase for quite a variety of flexible substrates including aliphatic nitriles, isonitriles, amines, alcohols, ketones, alkynes, and allenes, respectively. Specifically, we have shown that the C-H bond of a terminal methyl group of an alkyl chain can be oxidatively added to the anchored transition-metal ion M{sup +} (Scheme II). The insertion is followed by a {beta}-hydrogen shift (5 {yields} 6) or {beta}-cleavage of the C-C bond (5 {yields} 7) to generate intermediates from which eventually reductive elimination of H{sub 2} of ligand detachment occurs. This discussion will be confined to recent results from our laboratory. While most of the data will be concerned with the chemistry of aliphatic nitriles, the reactions of alkynesmore » with bare transition-metal ions will be briefly mentioned.« less

Activation of carbon-hydrogen and carbon-carbon bonds of 4-octyne in the gas phase by bare transition-metal ions M+ (M = chromium, manganese, iron)

Activation of carbon-hydrogen and carbon-carbon bonds of 4-octyne in the gas phase by bare transition-metal ions M+ (M = chromium, manganese, iron)