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 [(4R)-5-(2-amino-6-oxo-1H-purin-9-yl)-4-[[(3S,4R)-5-(6-aminopurin-9-yl)-3,4-dihydroxyoxolan-2-yl]methoxy-hydroxyphosphoryl]-3-methylideneoxolan-2-yl]methoxy-hydroxy-oxophosphanium .
user
C21H25N10O11P2+
assistant