title: Methane Activation by Tantalum Carbide Cluster Anions Ta2C4.
abstract: Methane activation by transition metals is of fundamental interest and practical importance, as this process is extensively involved in the natural gas conversion to fuels and value-added chemicals. While single-metal centers have been well recognized as active sites for methane activation, the active center composed of two or more metal atoms is rarely addressed and the detailed reaction mechanism remains unclear. Here, by using state-of-the-art time-of-flight mass spectrometry, cryogenic anion photoelectron imaging spectroscopy, and quantum-chemical calculations, the cooperation of the two Ta atoms in a dinuclear carbide cluster Ta2C4-for methane activation has been identified. The C-H bond activation takes place predominantly around one Ta atom in the initial stage of the reaction and the second Ta atom accepts the delivered H atom from the C-H bond cleavage. The well-resolved vibrational spectra of the cryogenically cooled anions agree well with theoretical simulations, allowing the clear characterization of the structure of Ta2C4-cluster. The reactivity comparison between Ta2C4-cluster and the carbon-less analogues (Ta2C3-and Ta2C2-) demonstrated that the cooperative effect of the two metal atoms can be well tuned by the carbon ligands in terms of methane activation and transformation.
authors.affiliation: Beijing National Laboratory for Molecular Sciences, State Key Laboratory for Structural Chemistry of Unstable and Stable Species, Institute of Chemistry, Chinese Academy of Sciences , Beijing 100190, P. R. China.|University of Chinese Academy of Sciences , Beijing 100049, P. R. China.
authors.forename: Hai-Fang
authors.initials: HF
authors.lastname: Li
authors.affiliation: Beijing National Laboratory for Molecular Sciences, State Key Laboratory for Structural Chemistry of Unstable and Stable Species, Institute of Chemistry, Chinese Academy of Sciences , Beijing 100190, P. R. China.
authors.forename: Yan-Xia
authors.initials: YX
authors.lastname: Zhao
authors.affiliation: Beijing National Laboratory for Molecular Sciences, State Key Laboratory for Structural Chemistry of Unstable and Stable Species, Institute of Chemistry, Chinese Academy of Sciences , Beijing 100190, P. R. China.
authors.forename: Zhen
authors.initials: Z
authors.lastname: Yuan
authors.affiliation: Beijing National Laboratory for Molecular Sciences, State Key Laboratory for Structural Chemistry of Unstable and Stable Species, Institute of Chemistry, Chinese Academy of Sciences , Beijing 100190, P. R. China.|University of Chinese Academy of Sciences , Beijing 100049, P. R. China.
authors.forename: Qing-Yu
authors.initials: QY
authors.lastname: Liu
authors.affiliation: Beijing National Laboratory for Molecular Sciences, State Key Laboratory for Structural Chemistry of Unstable and Stable Species, Institute of Chemistry, Chinese Academy of Sciences , Beijing 100190, P. R. China.
authors.forename: Zi-Yu
authors.initials: ZY
authors.lastname: Li
authors.affiliation: Beijing National Laboratory for Molecular Sciences, State Key Laboratory for Structural Chemistry of Unstable and Stable Species, Institute of Chemistry, Chinese Academy of Sciences , Beijing 100190, P. R. China.
authors.forename: Xiao-Na
authors.initials: XN
authors.lastname: Li
authors.affiliation: Department of Physics, State Key Laboratory of Low-Dimensional Quantum Physics, Tsinghua University , Beijing 100084, P. R. China.
authors.forename: Chuan-Gang
authors.initials: CG
authors.lastname: Ning
authors.affiliation: Beijing National Laboratory for Molecular Sciences, State Key Laboratory for Structural Chemistry of Unstable and Stable Species, Institute of Chemistry, Chinese Academy of Sciences , Beijing 100190, P. R. China.
authors.forename: Sheng-Gui
authors.identifier: http://orcid.org/0000-0002-9919-6909
authors.initials: SG
authors.lastname: He