You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
[5-(4-chlorophenyl)thiophen-2-yl]-(3,9-diazabicyclo[4.2.1]nonan-9-yl)methanone is the IUPAC name of a molecule. Please give its molecular formula.
user
C18H19ClN2OS
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