You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
Please write the molecular formula of the molecule [2-[4-[(5-chlorothiophen-2-yl)methyl]piperazin-1-yl]-2-oxoethyl] 2-thieno[2,3-d]pyrimidin-4-ylsulfanylacetate .
user
C19H19ClN4O3S3
assistant