Experimental and theoretical study of the recombination reactions of FS(O-2)O with FC(O)O and CO

The laser flash photolysis technique has been used to study the kinetics of the reactions of FS(O-2)O with FC(O)O and CO at 296 K. Both reactions were found to be essentially in the second-order regime at total pressures rang ing from 160 to 1020 mbar of the radical precursors FS(O-2)OF, CO and O-2 a nd the bath gas SF6. The FS(O-2)O and FC(O)O radicals were monitored by abs orption spectroscopy at 450 and 545 nm. The determined limiting high pressu re rate coefficients for the FC(O)O+FS(O-2)O --> FC(O)OO(O-2)SF and FS(O-2) O+CO --> FS(O-2)OCO reactions are 1.0 +/-0.1x10(-12) and 4.3 +/-0.9x10(-17) cm(3) molecule(-1) s(-1). Employing isodesmic reaction schemes with total energies calculated at the B3LYP/6-311++G(3df,p)//B3LYP/6-311++G(d,p) level of theory, enthalpies of formation for FS(O-2)O, FS(O-2)O-2, FS(O-2)OF, FS (O-2)OCO, FS(O-2)OC(O)CO, FS(O-2)OC(O)O-2, FC(O)OO(O-2)SF, FCO, FC(O)O and FC(O)O-2 molecules were derived. An analysis of the rate coefficients in te rms of the statistical adiabatic channel model and the transition state the ory on potential energy surfaces derived from density functional theory cal culations has been carried out.