You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
4-(3-chloro-2-fluorocyclohexa-1,5-dien-1-yl)-2-[(3-methyloxetan-3-yl)methyl]pyrrolidine-3-carbonitrile;4-chloro-2-fluorophosphinine is the IUPAC name of a molecule. Please give its molecular formula.
user
C21H23Cl2F2N2OP
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