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 CF4 and C2F4 are −223.1±1.1 and −160.5±1.5 kcal/mol, respectively. The CF4 value is in excellent agreement with experiment (−223.04±0.18 kcal/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 also shows that the G3 value has the expected error of ±2 kcal/mol.