The latter are scaled by 0.9886, 0.9926 and 0.9970 to account for the zero-point energy, the thermal corrections to the enthalpy and entropy respectively. Energetics are computed by a combination of coupled-cluster determinations, CCSD(T) and CCSD(T)-F12b, extrapolated to the complete basis set limit (CBS) with aug-cc-pVnZ basis sets up to aug-cc-pVQZ. Core valence correlation and scalar relativistic calculations were performed at the CCSD(T)/cc-pCVTZ level using non-relativistic frozen-core and and all-electron Douglas-Kroll-Hess methods and MP2 and CCSD(T) energies. The above signifies the W2X component of the W3X-L method computed by the Molpro 26 code; the final steps involve post-CCSD(T) effects up to CCSDT(Q) using the multi-reference application MRCC. In some cases the computationally less-demanding WMS method has been used, also centered on B3LYP/cc-pVTZ+d geometries and not on those originally specified by the WMS from the functional geometry, that is W-F12//B3LYP/Def2-TZVPP, exhibit a root-meansquare deviation of only 0.29 kJ mol -1 and that using a cc-pVTZ+d basis set leads to even better, if unspecified, results. Since only CHNO species are considered here cc-pVTZ+d is equivalent to cc-pVTZ.