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Title:SINGLE ATOM CATALYTIC CYCLOTRIMERIZATION OF V(ACETYLENE)3+ STUDIED WITH INFRARED SPECTROSCOPY
Author(s):Marks, Joshua H
Contributor(s):Duncan, Michael A.; Ward, Timothy B.
Subject(s):Ions
Abstract:Vanadium cation is studied as a model system for single atom catalysis in the gas phase with infrared photodissociation spectroscopy. Intermediates in the cyclotrimerization of acetylene to form benzene are observed. V(C$_{2}$H$_{2}$)$_{n}$$^{+}$ clusters are produced via laser vaporization of vanadium in a supersonic expansion of argon containing acetylene. Clusters of V(C$_{2}$H$_{2}$)$^{+}$, V(C$_{2}$H$_{2}$)$_{2}$$^{+}$, and V(C$_{2}$H$_{2}$)$_{3}$$^{+}$ are studied with infrared photodissociation spectroscopy with the aid of argon tagging in the C–H stretching region. These spectra are assigned on the basis of B3LYP computations. V(C$_{2}$H$_{2}$)$^{+}$ is a three membered metallacycle, where the hydrogens bend away from the vanadium. V(C$_{2}$H$_{2}$)$_{2}$$^{+}$ is a bimetallacycle where both acetylene ligands interact with vanadium symmetrically through their $\pi$-bonds in a C$_{2v}$ configuration. The structure of V(C$_{2}$H$_{2}$)$_{3}$$^{+}$ is found to vary with the concentration of acetylene in the supersonic expansion. At low concentrations of acetylene two isomers of V(C$_{2}$H$_{2}$)$_{3}$$^{+}$ are observed, a trimetallacycle, and a bimetallacycle which includes a five membered ring and a three membered ring. As the concentration of acetylene is increased past 5\% the trimetallacycle decreases in abundance. Benzene is observed at yet higher concentration of acetylene. An expansion gas consisting of 15\% acetylene in argon results in the exclusive formation of V(Bz)$^{+}$.
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/2142/100478
DOI:10.15278/isms.2018.FE07
Other Identifier(s):FE07
Date Available in IDEALS:2018-08-17
2018-12-12


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