Electronic effect in C-H and C-C bond activation: state-specific reactions of Fe/sup +/(/sup 6/D, /sup 4/F) with methane, ethane, and propane
Reactions of atomic iron ions with methane, ethane, and propane are studied with guided ion beam mass spectrometry. By using different ion sources different electronic states of the ion can be prepared and studied in detail. The first excited state, Fe/sup +/(/sup 4/F), is more reactive than the ground state, Fe/sup +/(/sup 6/D), for all endothermic reactions in all three systems. This result is similar to recent observations of the reactions of these states with H/sub 2/. The different reactivities are explained by using simple molecular orbital arguments. In contrast, Fe/sup +/(/sup 4/F) reacts less efficiently than Fe/sup +/(/sup 6/D) in the exothermic reactions of ethane and propane below 0.5 eV but more efficiently at higher energies. This behavior is explained by a potential energy surface crossing that is avoided at low kinetic energies due to spin-orbit interactions and is permitted at higher energies. Finally, analysis of the threshold behavior of the endothermic reactions provides the bond dissociation energies, D/sup 0/(Fe/sup +/-CH/sub 3/) = 2.51 +/- 0.10 eV (57.9 +/- 2.4 kcal/mol) and D/sup 0/(FeH) = 1.98 +/- 0.13 eV (45.7 +/- 3.0 kcal/mol).
- Research Organization:
- Univ. of California, Berkeley
- OSTI ID:
- 5419319
- Journal Information:
- J. Am. Chem. Soc.; (United States), Vol. 110:2
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
ETHANE
CHEMICAL REACTIONS
IRON
EXCITED STATES
GROUND STATES
METHANE
PROPANE
CARBON
CATIONS
CHEMICAL BONDS
CHEMICAL REACTION KINETICS
DISSOCIATION ENERGY
EXPERIMENTAL DATA
HYDROGEN
MASS SPECTROSCOPY
ALKANES
CHARGED PARTICLES
DATA
ELEMENTS
ENERGY
ENERGY LEVELS
HYDROCARBONS
INFORMATION
IONS
KINETICS
METALS
NONMETALS
NUMERICAL DATA
ORGANIC COMPOUNDS
REACTION KINETICS
SPECTROSCOPY
TRANSITION ELEMENTS
400201* - Chemical & Physicochemical Properties