Revised and modified mechanisms for the reactions of bare transition-metal ions M sup + (M = Fe, Co, Ni) with n-C sub 3 H sub 7 X (X = NH sub 2 , OH) in the gas phase
- Universitaet Berlin (Germany, F.R.)
The metastable ion (MI) decompositions of n-C{sub 3}H{sub 7}X/M{sup +} complexes (X = H, NH{sub 2}; M = Fe, Co, Ni) in the gas phase have been studied by tandem mass spectrometry. The analysis of the MI spectra of a large set of isotopomers uncovers processes which require a revision and modification of the previously suggested mechanisms for the activation of CH and CC bonds in these particular systems. Highlights of the novel findings are inter alia the observation that Fe{sup +}-mediated ethylene loss from n-C{sub 3}H{sub 7}NH{sub 2} involves the {alpha}- and {beta}-methylene units. Scrambling of these intact CH{sub 2} groups precedes the {beta}-hydrogen transfer which eventually leads to NH{sub 3} and C{sub 3}H{sub 6} from C{sub 3}H{sub 7}NH{sub 2}/Fe{sup +}. For the Co{sup +} and Ni{sup +} complexes this exchange process is not observed, and ethylene loss can be described in terms of the remote functionalization concept. In the n-C{sub 3}H{sub 7}OH/M{sup +} system, the most unexpected findings concern the mechanism of the competitive formations of CH{sub 3}OH and C{sub 2}H{sub 4}. For M{sup +} = Co{sup +}, methanol contains the intact methyl and OH groups of the precursor propanol and C{sub 2}H{sub 4} originates from the internal part of the alkyl chain (C({alpha})/C({beta})). This reaction sequence is to approximately 20% also operative for the Ni{sup +} system. In addition, the anchored Ni{sup +} induces cleavage of the C({alpha})/C({beta}) bond to eventually generate C{sub 2}H{sub 4} (containing C({beta}) and C({gamma})) and CH{sub 3}OH. The methyl group of the latter contains the original {alpha}-CH{sub 2} unit and one hydrogen from the CH{sub 3} group of propanol. The results underline the necessity of employing labeled presursors in mechanistic studies of organometallic systems in the gas phase.
- OSTI ID:
- 6972201
- Journal Information:
- Journal of the American Chemical Society; (USA), Journal Name: Journal of the American Chemical Society; (USA) Vol. 111:25; ISSN 0002-7863; ISSN JACSA
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
400000* -- Chemistry
400201 -- Chemical & Physicochemical Properties
CATALYSIS
CHEMICAL REACTIONS
DATA
DATA ANALYSIS
DECOMPOSITION
EXPERIMENTAL DATA
INFORMATION
MASS SPECTROSCOPY
MEASURING INSTRUMENTS
MEASURING METHODS
NUMERICAL DATA
SPECTROSCOPY
TRANSITION ELEMENT COMPOUNDS