Infrared spectroscopy of Zn(acetylene)1−5+: Evidence of acetylene activation by a metal radical

Marks, Joshua H

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https://hdl.handle.net/2142/100835 Copy

Description

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.

Issue Date

2018-06-22

Keyword(s)

Ions

Abstract

Zinc cation is studied as a model system for single atom catalysis in the gas phase with infrared photodissociation spectroscopy. Zn(C2H2)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(C2H2) + is found to consist of a C2v three membered metallacycle, where zinc is equidistant from both carbon atoms of acetylene. Zn(C2H2)2 + does not contain a metallacycle, but features zinc binding more closely to one of the carbon atoms of each acetylene in a C2 configuration. The three-coordinate cluster is predicted to be lowest in energy as a π-bound D3h structure, with a low energy C3 structure. When the spectrum of this cluster is measured with argon tagging the D3h isomer is most abundant. When measured without the tag the C3 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.

Publisher

International Symposium on Molecular Spectroscopy

Type of Resource

text

Language

eng

Permalink

http://hdl.handle.net/2142/100835

DOI

10.15278/isms.2018.FE06

Copyright and License Information

Copyright 2018 Joshua H. Marks

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