You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
What is the molecular formula of the molecule 2'-[2-(4-dibenzofuran-4-ylphenyl)-2-(9,9-dimethylfluoren-2-yl)ethyl]spiro[9-oxapentacyclo[11.7.0.02,10.03,8.015,20]icosa-1(13),2(10),3,5,7,11,15,17,19-nonaene-14,9'-fluorene] ?
user
C66H44O2
assistant