You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
4-phenyl-6-(2-phenylpyrimidin-5-yl)-2-spiro[tetracyclo[13.4.0.02,7.08,13]nonadeca-1(19),2,4,6,8(13),9,11,15,17-nonaene-14,9'-thioxanthene]-11-ylpyrimidine is the IUPAC name of a molecule. Please give its molecular formula.
user
C51H32N4S
assistant