Characterization of a carbon dioxide-hexaflourobenzene complex using Matrix Isolation Infrared Spectroscopy

Amicangelo, Jay C.

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https://hdl.handle.net/2142/97164 Copy

Description

Title

Characterization of a carbon dioxide-hexaflourobenzene complex using Matrix Isolation Infrared Spectroscopy

Author(s)

Amicangelo, Jay C.

Contributor(s)

• Horn, Maryn N.
• Gall, Bradley K.

Issue Date

2017-06-23

Keyword(s)

Clusters/complexes

Abstract

Matrix isolation infrared spectroscopy was used to characterize a 1:1 complex of carbon dioxide (chem{CO_2}) with hexaflourobenzene (chem{C_6F_6}). Co-deposition experiments with chem{CO_2} and chem{C_6F_6} were performed at 20 K using argon as the matrix gas. New infrared peaks attributable to the chem{CO_2}-chem{C_6F_6} complex were observed near the O-C-O antisymmetric stretching vibration of the chem{CO_2} monomer and near the C-F stretching vibration of the chem{C_6F_6} monomer. The initial identification of the newly observed infrared peaks to those of a chem{CO_2}-chem{C_6F_6} complex was established by performing several concentration studies in which the sample-to-matrix ratios of the monomers were varied between 1:100 to 1:1600, by comparing the resulting co-deposition spectra with the spectra of the individual monomers, and by matrix annealing experiments (30 – 35 K). Co-deposition experiments were also performed using isotopically labeled carbon dioxide ($^{13}$chem{CO_2}) and the analogous peaks for the $^{13}$chem{CO_2}-chem{C_6F_6} complex were observed. Quantum chemical calculations were performed for the chem{CO_2}-chem{C_6F_6} complex at the MP2/aug-cc-pVDZ level of theory in order to explore the intermolecular potential energy surface of the complex and to obtain optimized complex geometries and predicted vibrational frequencies of the complex. The calculations for the exploration of the potential energy surface involved rigid scans along the intermolecular distance and various angle coordinates for several general orientations of the two monomers. Based on these calculations, full geometry optimizations were then performed and two stable complex minima were found: one in which the chem{CO_2} is perpendicular and centered to the chem{C_6F_6} ring ($Delta$E$_{int}$ = -7.9 kJ/mol) and one in which the chem{CO_2} is parallel to the chem{C_6F_6} ring but displaced from the center ($Delta$E$_{int}$ = -6.0 kJ/mol). Comparing the predicted vibrational spectra for both complexes to the observed experimental spectra, particularly for the O-C-O antisymmetric stretching region, it is concluded that both structures are present in the solid argon matrices.

Publisher

International Symposium on Molecular Spectroscopy

Type of Resource

text

Language

eng

Permalink

http://hdl.handle.net/2142/97164

DOI

https://doi.org/10.15278/isms.2017.FD01

Copyright and License Information

Copyright 2017 Jay C. Amicangelo

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