Rate coefficient for the reaction FCO+FC(O)O-2 -> 2FC(O)O at 296 K

The kinetics of the reaction FCO + FC(O)O-2 --> 2FC(O)O has been studied. T he reactants were generated by KrF excimer laser flash photolysis of mixtur es of (FCO)(2) and O-2 in excess of M = SF6 at 296 K. The three radicals we re monitored by absorption spectroscopy. Assuming that the reaction proceed s through a complex-forming process, the measured rate coefficient, (2.1 +/ - 0.5) X 10(-11) cm(3) molecule(-1) s(-1), agrees with that predicted by a simplified version of the statistical adiabatic channel model using a ratio alpha/beta = 0.50 between the looseness and the Morse parameters. A rate c oefficient of (3.7 +/- 0.2) X 10(-12) cm(3) molecule(-1) s(-1) was determin ed for the FC(O)O + FC(O)O-2 + M --> (FCO)(2)O-3 + M reaction. Employing is odesmic reaction schemes at the B3LYP/6-311 + + G(d,p) level of theory, the enthalpy of formation of FC(O)O-2 and (FCO)(2)O-2 are calculated to be -76 .1 +/- 4 and -202.9 +/- 4 kcal mol(-1), respectively. (C) 1999 Elsevier Sci ence B.V. All rights reserved.