Systematic Determination Of the Structure and Point Group of the Acetloxy Radical from Density Functional Calculations

Beattie, Jeffery, and Jonathan Stevens

 The acetyloxy radical (CH3COO) is a species commonly involved in atmospheric reactions. To date, most computational studies of this radical have either exclusively studied symmetric (Cs) structures, or have located such structures as minima with optimizations performed with relatively low levels of computation. Our work investigates the structure of this radical with intensive calculations using newly developed density functional methods and large basis sets. We will present optimizations of the acetyloxy radical using the M052X density functional theory method and 6-311G(d,p), 6-311+G(d,p), 6-311++G(d,p), 6-311G(2d,2p), 6-311+G(2d,2p), 6-311++G(2d,2p), 6-311G(3df,2p), 6-311+G(3df,2p), and 6-311++G(3df,2p) basis sets.
The highest level calculations show that the correct point group of this species to be a Cs structure in which all atoms of the CO2 moiety are ian-plane with a methyl hydrogen (structure Cs-1). The relative stability of the asymmetric minimum C1 will be compared at all levels of computation to the energy of CS-1 and also to the other possible Cs structure, in which the CO2 moiety is rotated ninety degrees (structure CS-2). Additional model chemistry calculations will intensively study the relative stabilities of possible structures.