title: Preferential activation of primary C-H bonds in the reactions of small alkanes with the diatomic MgO(+*) cation.
abstract: The C-H bond activation of small alkanes by the gaseous MgO(+*) cation is probed by mass spectrometric means. In addition to H-atom abstraction from methane, the MgO(+*) cation reacts with ethane, propane, n- and iso-butane through several pathways, which can all be assigned to the occurrence of initial C-H bond activations. Specifically, the formal C-C bond cleavages observed are assigned to C-H bond activation as the first step, followed by cleavage of a beta-C-C bond concomitant with release of the corresponding alkyl radical. Kinetic modeling of the observed product distributions reveals a high preference of MgO(+*) for the attack of primary C-H bonds. This feature represents a notable distinction of the main-group metal oxide MgO(+*) from various transition-metal oxide cations, which show a clear preference for the attack of secondary C-H bonds. The results of complementary theoretical calculations indicate that the C-H bond activation of larger alkanes by the MgO(+*) cation is subject to pronounced kinetic control.
authors.affiliation: Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, Flemingovo námestí 2, 16610 Prague 6, Czech Republic. schroeder@uochb.cas.cz
authors.forename: Detlef
authors.initials: D
authors.lastname: Schröder
authors.forename: Jana
authors.initials: J
authors.lastname: Roithová
authors.forename: Esmail
authors.initials: E
authors.lastname: Alikhani
authors.forename: Karolina
authors.initials: K
authors.lastname: Kwapien
authors.forename: Joachim
authors.initials: J
authors.lastname: Sauer