TY - JOUR
T1 - Electronic effects in C-H and C-C bond activation
T2 - State-specific reactions of Fe+(6D,4F) with methane, ethane, and propane
AU - Schultz, Richard H.
AU - Elkind, J. L.
AU - Armentrout, P. B.
PY - 1988/1
Y1 - 1988/1
N2 - 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+(4F), is more reactive than the ground state, Fe+(6D), for all endothermic reactions in all three systems. This result is similar to recent observations of the reactions of these states with H2. The different reactivities are explained by using simple molecular orbital arguments. In contrast, Fe+(4F) reacts less efficiently than Fe+(6D) 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°(Fe+-CH3) = 2.51 ± 0.10 eV (57.9 ± 2.4 kcal/mol) and D°(FeH) = 1.98 ± 0.13 eV (45.7 ± 3.0 kcal/mol).
AB - 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+(4F), is more reactive than the ground state, Fe+(6D), for all endothermic reactions in all three systems. This result is similar to recent observations of the reactions of these states with H2. The different reactivities are explained by using simple molecular orbital arguments. In contrast, Fe+(4F) reacts less efficiently than Fe+(6D) 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°(Fe+-CH3) = 2.51 ± 0.10 eV (57.9 ± 2.4 kcal/mol) and D°(FeH) = 1.98 ± 0.13 eV (45.7 ± 3.0 kcal/mol).
UR - http://www.scopus.com/inward/record.url?scp=33845279486&partnerID=8YFLogxK
U2 - 10.1021/ja00210a017
DO - 10.1021/ja00210a017
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AN - SCOPUS:33845279486
SN - 0002-7863
VL - 110
SP - 411
EP - 423
JO - Journal of the American Chemical Society
JF - Journal of the American Chemical Society
IS - 2
ER -