You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
Convert the IUPAC name of a molecule benzylsulfanyl-oxido-phenylmethoxy-sulfanylidene-lambda5-phosphane;1-methyl-3-prop-2-enylimidazol-1-ium into molecular formula.
user
C21H25N2O2PS2
assistant