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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:2018-08-17
2018-12-12


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