Cytidine 5′-monophosphate-d 12 (5'-Cytidylic acid-d 12 dilithium; 5'-CMP-d 12 ) dilithium is deuterium labeled Cytidine 5'-monophosphate. Cytidine 5'-monophosphate (5'-Cytidylic acid) is a nucleotide which is used as a monomer in RNA. Cytidine 5'-monophosphate consists of the nucleobase cytosine, the pentose sugar ribose, and the phosphate group.