You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
1-(4-chlorophenyl)-2-[3-(3,5,8,10-tetrazatricyclo[7.3.0.02,6]dodeca-1,4,6,8,11-pentaen-3-yl)-1-bicyclo[1.1.1]pentanyl]ethanone The above is the IUPAC name of a molecule. Write its molecular formula.
user
C21H17ClN4O
assistant