DETERMINATION OF THE HEATS OF FORMATION OF FC(O)O AND FC(O)OH

We present ab initio calculations of the heats of formation of (fluoroformyl)oxyl, FC(O)O, which is an intermediate in the stratospheric photo-oxidation of halocarbons, and fluoroformic acid, FC(O)OH. The G1 and G2 levels of theory are employed for both species. At 0 K G2 (G1) values are -88.0 (-87.2) kcal mol(-1) for FC(O)O and -148.0 (-146.6) for FC(O)OH. An isodesmic reaction yields a heat of formation of FC(O)OH of -146.9 +/- 3, the uncertainty arising largely from possible errors in the experimental data for other species in the reaction. The O-H bond energy of FC(O)OH is 111.6 (111.0) kcal mol(-1), about the same as that of the C-H bond in methane (similar to 110 kcal mol(-1)).