Rate coefficient for the reaction FCO+FC(O)O2→2 FC(O)O at 296 K

The kinetics of the reaction FCO+FC(O)O2→2 FC(O)O has been studied. The reactants were generated by KrF excimer laser flash photolysis of mixtures of (FCO)2 and O2 in excess of M=SF6 at 296 K. The three radicals were monitored by absorption spectroscopy. Assuming that the reaction proceeds through a complex-forming process, the measured rate coefficient, (2.1±0.5)×10−11 cm3 molecule−1 s−1, agrees with that predicted by a simplified version of the statistical adiabatic channel model using a ratio α/β=0.50 between the looseness and the Morse parameters. A rate coefficient of (3.7±0.2)×10−12 cm3 molecule−1 s−1 was determined for the FC(O)O+FC(O)O2+M→(FCO)2O3+M reaction. Employing isodesmic reaction schemes at the B3LYP/6-311++G(d,p) level of theory, the enthalpy of formation of FC(O)O2 and (FCO)2O2 are calculated to be −76.1±4 and −202.9±4 kcal mol−1, respectively.