You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
Under IUPAC nomenclature, a molecule named 6-butan-2-yl-N,9-diphenyl-N-(9,9'-spirobi[fluorene]-2-yl)carbazol-3-amine;6-butyl-N,9-diphenyl-N-(9,9'-spirobi[fluorene]-2-yl)carbazol-3-amine;6-(2-methylpropyl)-N,9-diphenyl-N-(9,9'-spirobi[fluorene]-2-yl)carbazol-3-amine is given. What is its corresponding molecular formula?
user
C159H120N6
assistant