FOURIER TRANSFORM MICROWAVE SPECTRA OF CO${_{2}}$-ETHYLENE SULFIDE,CO${_{2}}$-ETHYLENE OXIDE AND CO${_{2}}$-PROPYLENE OXIDE COMPLEXES
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Date
2010
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Publisher
Ohio State University
Abstract
We have previously examined the difference in roles of O and S in structure and dynamics of the CO-ethylene oxide (EO) and CO-ethylene sulfide (ES) complexes, WF05 (2008).}. We have extended the investigation to CO${_{2}}$-EO and CO${_{2}}$-ES for comparison. We have also observed the CO${_{2}}$-propylene oxide (PO) complex, which is an important intermediate in the reaction of PO with CO${_{2}}$ leading to polycarbonate. Both $a$-type and $b$-type transitions were observed for the CO${_{2}}$-EO and CO${_{2}}$-ES, but no $c$-type transitions were observed at all. We also detected the ${^{34}}$S and ${^{13}}$C isotopic species in natural abundance and the species containing ${^{18}}$OCO and C${^{18}}$O$% {_{2}}$, which were synthesized by burning paper in an ${^{18}}$O${_{2}}$ and${% ^{16}}$O${_{2}}$ mixture. By analyzing the observed spectra we concluded the CO${_{2}}$ moiety of CO${_{2}}$-EO and CO${_{2}}$-ES located in a plane $% prependicular$ to the three-membered ring and bisecting the COC or CSC angle of EO or ES, respectively, as in the case of CO-EO and CO-ES complexes. An $% ab$ $initio$ MO calculation at the level of MP2/6-311G($d$, $p$) yielded an optimized structure in good agreement with the experimental result. We have derived from the observed spectra the distance, the stretching force constant, and the binding energy of the bonds between the constituents of the CO${_{2}}$-EO and CO${_{2}}$-ES complexes and have found that the distances of the two complexes were shorter by 0.2\AA~ than those in CO-EO and CO-ES, respectively, and that the intermolecular bonds were two times stronger in the CO${_{2}}$ complexes than in the corresponding CO complexes. We have concluded from the observed spectra that the CO${_{2}}$ moiety in CO${_{2}}$-PO is located on the PO three-membered ring plane opposite to the methyl group. The constituents in CO${_{2}}$-PO were more weakly bound than those in CO${_{2}}$-EO and CO${_{2}}$-ES.
Description
Author Institution: Department of Applied Chemistry, Faculty of Engineering, Kanagawa Institute of Technology, Atsugi, Kanagawa 243-0292, JAPAN; The Graduate University for Advanced Studies, Hayama, Kanagawa 240-0193, JAPAN