You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
2-[4-[4-(2,5-dimethylthiophen-3-yl)sulfonylpiperazin-1-yl]-4-oxobutyl]isoindole-1,3-dione is the IUPAC name of a molecule. Please give its molecular formula.
user
C22H25N3O5S2
assistant