Density functional calculations on the effect of sulfur substitution for 2′-hydroxypropyl-p-nitrophenyl phosphate: CO vs. PO bond cleavage

► The geometries of the stationary points in water solution were optimized. ► The P-path is accessible for HPpNP, but for s-2′pNP the C-path is favorable. ► The calculated energy barriers are in agreement with the experimental results.