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 Title: INFRARED SPECTROSCOPY OF Zn(ACETYLENE)1−5+: EVIDENCE OF ACETYLENE ACTIVATION BY A METAL RADICAL Author(s): Marks, Joshua H Contributor(s): Duncan, Michael A.; Ward, Timothy B. Subject(s): Ions Abstract: Zinc cation is studied as a model system for single atom catalysis in the gas phase with infrared photodissociation spectroscopy. Zn(C$_{2}$H$_{2}$)$_{n}$$^{+} (n = 1–5) clusters are produced via laser vaporization of zinc in a supersonic expansion of acetylene and argon. Clusters are mass-selected and studied with infrared photodissociation spectroscopy in the C–H stretching region. Smaller clusters (n = 1–3) are studied with the use of a weakly bound argon tag. These spectra are assigned with B3LYP/Def2TZVP computational studies. Zn(C_{2}H_{2})^{+} is found to consist of a C_{2v} three membered metallacycle, where zinc is equidistant from both carbon atoms of acetylene. Zn(C_{2}H_{2})_{2}$$^{+}$ does not contain a metallacycle, but features zinc binding more closely to one of the carbon atoms of each acetylene in a C$_{2}$ configuration. The three-coordinate cluster is predicted to be lowest in energy as a $\pi$-bound D$_{3h}$ structure, with a low energy C$_{3}$ structure. When the spectrum of this cluster is measured with argon tagging the D$_{3h}$ isomer is most abundant. When measured without the tag the C$_{3}$ isomer is found to be in abundance. The spectra of the four and five coordinate clusters are found to contain a feature 160 cm$^{-1}$ to the red of the acetylene C–H asymmetric stretch. This is attributed to a fourth acetylene ligand forming a metal vinyl radical, accompanied by formation of Zn(II). This transfer of the radical center from zinc to a ligand activates the acetylene, and could be the first step in single atom catalysis by zinc. Issue Date: 06/22/18 Publisher: International Symposium on Molecular Spectroscopy Citation Info: APS Genre: Conference Paper / Presentation Type: Text Language: English URI: http://hdl.handle.net/2142/100835 DOI: 10.15278/isms.2018.FE06 Other Identifier(s): FE06 Date Available in IDEALS: 2018-08-172018-12-12
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