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Abstract
Quantum chemical studies have been carried out on prototypical gas-phase molecular systems relevant to atmospheric, combustion, and organometallic chemistry. Numerous processes in atmospheric and combustion chemistry produce vinoxy radicals. To understand the fate of these radicals and to provide reliable energies needed for kinetic modeling, we have examined the reactions of the unsubstituted vinoxy radical and the 1-methylvinoxy (acetonyl) radical with O2 using highly reliable theoretical methods. Geometries were obtained using coupled cluster theory with singles, doubles, and perturbative triple excitations [CCSD(T)]. Energetics were computed to chemical accuracy using the focal point approach involving perturbative treatment of quadruple excitations [CCSDT(Q)] and basis sets as large as cc-pV5Z. In addition, the vinoxy radical + O2 entrance channel has been studied with multireference methods for the first time. Vinoxy radical + O2 reactions produce peroxy radicals (ROO•), and the unimolecular isomerization pathways of these molecules are explored. Computational studies have also been performed on transition metal carbenes, systems that are widely useful in organometallic chemistry. The prototypical transition metal methylene complexes of metals in groups 6, 8, and 10 were studied with a variety of DFT functionals. Though none of these complexes has yet been synthesized experimentally, spectroscopic observation of several of these molecules should be possible.