title: Reactivity of oxygen radical anions bound to scandia nanoparticles in the gas phase: C-H bond activation.
abstract: The activation of C-H bonds in alkanes is currently a hot research topic in chemistry. The atomic oxygen radical anion (O(-·)) is an important species in C-H activation. The mechanistic details of C-H activation by O(-·) radicals can be well understood by studying the reactions between O(-·) containing transition metal oxide clusters and alkanes. Here the reactivity of scandium oxide cluster anions toward n-butane was studied by using a high-resolution time-of-flight mass spectrometer coupled with a fast flow reactor. Hydrogen atom abstraction (HAA) from n-butane by (Sc2O3)(N)O(-) (N=1-18) clusters was observed. The reactivity of (Sc2O3)(N)O(-) (N=1-18) clusters is significantly sizedependent and the highest reactivity was observed for N=4 (Sc8O13(-)) and 12 (Sc24O37(-)). Larger (Sc2O3)(N)O(-) clusters generally have higher reactivity than the smaller ones. Density functional theory calculations were performed to interpret the reactivity of (Sc2O3)(N)O(-) (N=1-5) clusters, which were found to contain the O(-·) radicals as the active sites. The local charge environment around the O(-·) radicals was demonstrated to control the experimentally observed size-dependent reactivity. This work is among the first to report HAA reactivity of cluster anions with dimensions up to nanosize toward alkane molecules. The anionic O(-·) containing scandium oxide clusters are found to be more reactive than the corresponding cationic ones in the C-H bond activation.
authors: Beijing National Laboratory for Molecular Sciences, State Key Laboratory for Structural Chemistry of Unstable and Stable Species, Institute of Chemistry, Chinese Academy of Sciences (P. R. China), Fax: (+86) 10-62559373; School of Chemistry and Chemical Engineering, South China University of Technology.
authors: Li-Hua
authors: LH
authors: Tian
authors: Jing-Heng
authors: JH
authors: Meng
authors: Xiao-Nan
authors: XN
authors: Wu
authors: Yan-Xia
authors: YX
authors: Zhao
authors: Xun-Lei
authors: XL
authors: Ding
authors: Sheng-Gui
authors: SG
authors: He
authors: Tong-Mei
authors: TM
authors: Ma
keywords: CH activation; cluster compounds; mass spectrometry; radical ions; scandium