You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
For the molecule named 6-(4-chlorophenyl)-3-(3-methoxy-4-pyrrolidin-1-ylphenyl)pyrrolo[2,1-f][1,2,4]triazin-4-one by IUPAC nomenclature, provide its molecular formula.
user
C23H21ClN4O2
assistant