**4. Conclusion**

Enthalpies of hydrogenation are relatively easy to calculate with CCSD(T)/ccpVXZ/M06-31g(d)/6-31g(d) level, where X = D, T, giving fairly good agreement

with experiment, especially when cc-pVTZ basis set are used, and basis set extrapolation techniques by Eq. (2) seem to represent an easy-to-use alternative, especially when the pair cc-pVDZ and cc-pVTZ are used.

