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.

Methane Activation Mediated by a Series of Cerium–Vanadium Bimetallic Oxide Cluster Cations: Tuning Reactivity by Doping

“…For (CeO 2 ) m (V 2 O 5 ) n + ( m =1,2, n =1–5; m =3, n =1–4) clusters, the estimated diameters of Ce 3 V 6 O 21 + is about 1 nm, and no obvious decrease of reactivity was observed in this series of clusters. However, in the reactions with methane, the reactivity of most of the reported cluster cations generally decreases with increasing cluster size, such as (Sc 2 O 3 ) 1–22 + , and (V 2 O 5 ) 2–11 + ; thus, clusters with dimensions of up to several nanometers may not be reactive for C−H activation in these systems. From V 2 O 5 + to (V 2 O 5 ) 10 + , the reaction rate constants of the reactions with methane decreased by three orders of magnitude .…”

Activation and Transformation of Ethane by Au2VO3+ Clusters with Closed‐Shell Electronic Structures

“…C−H activation of small alkanes by oxide clusters has been extensively studied by experiments, and most investigations emphasized the importance of O −. radicals such as La 6 O 10 − , AuNbO 3 + , YAlO 3 + , AlVO 5 − , V 2 Ag 2 O 6 + , and so on ,,–,. The oxide clusters without O −.…”

Study on the Reaction of Nanosized Yttrium Oxide Cluster Anions with n-Butane in the Gas Phase

“…对前过渡金属氧化物团簇(M x O y q )的研究发现 [21][22][23][24][25][26][27][28] , 可以通过定义氧缺陷指数(oxygen deficiency, ∆; 方程式 1)对其进行分类研究: ∆≡2y-mx＋q (1) 其中 q 为团簇电荷数, m 为金属 M 的最高价态. 过去, 关 于过渡金属氧化物团簇结构和反应性的研究主要集中 在小尺寸体系 [21][22][23][24][25]27] .…”