The heat of formation of C2F4

The CCSD(T) atomization energies are extrapolated to the complete basis set limit, and are corrected for zero-point energy, spin-orbit, core-valence, and scalar relativistic effects. Our best heats of formation at 298 K for C F4 and C2F4 are -223.1 +/- 1.1 and -160.5 +/- 1.5 kcal/mol, respectively. T he CF, value is in excellent agreement with experiment (- 223.04 +/- 0.18 k cal/mol), while the C2F4 result suggests that the experimental value (- 157 .6 +/- 0.6 kcal/mol) has a larger error than believed. Our value for C2F4 a lso shows that the G3 value has the expected error of +/-2 kcal/mol. (C) 19 99 Elsevier Science B.V. All rights reserved.