Hello, I use MarvinSkech 5.10.1.
Calculated pKa of fluorinated sulfonamides (sulfonamide group) are very different from experimentally observed. For example, pentafluorsulfonamide has calculated pKa 5.48, and experimental is 8.2.
Experimental data can be found in:
Thermodynamic parameters for the association of fluorinated benzenesulfonamides with bovine carbonic anhydrase II.
Thanks for reporting these miss-predicted pKa values.
The bug is fixed and the improved version will be available in the next bug-fix release. In the 5.12.x version.