1-[(2R,3R,4R,5S)-5-({[({[(2R,3S,4R,5R)-5-(6-amino-9H-purin-9-yl)-4-(hydrogen phosphonatooxy)-3-hydroxyoxolan-2-yl]methyl phosphonato}oxy)phosphinato]oxy}methyl)-3,4-dihydroxyoxolan-2-yl]-5-carbamoyl-3,4-dihydro-1λ⁵-pyridin-1-ylium