trilithium(1+) ion (3R)-3-{[2-({2-[(1-13C)hexadecanoylsulfanyl]ethyl}carbamoyl)ethyl]carbamoyl}-3-hydroxy-2,2-dimethylpropyl ({[(2R,3S,4R,5R)-5-(6-amino-9H-purin-9-yl)-3-(hydrogen phosphonatooxy)-4-hydroxyoxolan-2-yl]methyl phosphonato}oxy)phosphonate