You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
Can you give the molecular formula of the molecule 2-(3,4-dihydro-2H-1,5-benzodioxepin-7-ylsulfanyl)-1-[4-(4-fluorophenyl)piperazin-1-yl]ethanone ?
user
C21H23FN2O3S
assistant