Stabilized Molecular Diphosphorus Pentoxide, P2O5L2 (L = N-Donor Base), in the Synthesis of Condensed Phosphate–Organic Molecule Conjugates

Commercial phosphorus pentoxide reacts with some N-donor bases to give the adducts P2O5L2 and P4O10L3 (L = DABCO, pyridine, 4-tert-butylpyridine). The DABCO adducts were structurally characterized by single-crystal X-ray diffraction. It is proposed that P2O5L2 and P4O10L3 undergo interconversion through a "phosphate-walk" mechanism, which was evaluated using DFT calculations. P2O5(pyridine)2 (1) efficiently transfers monomeric diphosphorus pentoxide to phosphorus oxyanion nucleophiles, yielding substituted trimetaphosphates and cyclo-phosphonate-diphosphates (P3O8R)2- (R1 = nucleosidyl, phosphoryl, alkyl, aryl, vinyl, alkynyl, H, F). Hydrolytic ring-opening of these compounds forms linear derivatives [R1(PO3)2PO3H]3-, and nucleophilic ring-opening gives linear disubstituted [R1(PO3)2PO2R2]3- compounds.