Utilizing matrix isolation infrared spectroscopy, a 1:1 complex of carbon dioxide (CO2) and hexafluorobenzene (C6F6) was characterized in low temperature nitrogen matrices. Co-deposition experiments with CO2 and C6F6 were conducted in a nitrogen matrix at 17 K. Several infrared peaks for the CO2-C6F6 complex were observed near the O-C-O antisymmetric stretching vibration of CO2. Identification of the observed peaks of the CO2-C6F6 complex was established by performing experiments with varying concentrations of the CO2 and C6F6 relative to the nitrogen matrix, comparing the co-deposition spectra to the individual monomer spectra of CO2 and C6F6 in nitrogen matrices, as well as matrix annealing experiments (25 - 30 K). Experiments were repeated using the 13CO2 isotope and peaks for the 13CO2-C6F6 complex were also observed near the O-13C-O antisymmetric stretching vibration of the 13CO2. Quantum chemical calculations were performed for the CO2-C6F6 complex using the Gaussian03W computational chemistry program at the B3LYP and MP2 levels of theory with the aug-cc-pVDZ basis set to obtain the optimal geometries and to simulate the infrared spectrum for the CO2-C6F6 complex, which are used to assign peaks of the complex. Based on the calculations, three stable complex structures were determined; one in which the CO2 molecule is perpendicular and positioned directly above the center of the C6F6 ring and two in which the CO2 is parallel and off-center of the ring (parallel-displaced). Upon comparing the predicted and experimental spectra, infrared peaks due to each complex structure have been observed and assigned in the experimental spectra.

Characterization of a carbon dioxide-hexafluorobenzene complex using matrix isolation infrared spectroscopy

255th National Meeting (2018)

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