You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
For the molecule named 3-[[(1S,2R,3S,4R)-4-[2-chloro-6-(2,2-diphenylethylamino)purin-9-yl]-2,3-dihydroxycyclopentyl]amino]-2-methyl-3-oxopropanoic acid by IUPAC nomenclature, provide its molecular formula.
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C28H29ClN6O5
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