You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
Provide the molecular formula for the IUPAC named substance 8-phenyl-5-(1,3,6,8-tetramethylcarbazol-9-yl)spiro[1-aza-8-borapentacyclo[11.7.1.02,7.09,21.015,20]henicosa-2(7),3,5,9(21),10,12,15,17,19-nonaene-14,9'-fluorene] .
user
C53H39BN2
assistant