The experimental characterization data for [NH 4 ] 4 [11] is in good agreement with the literature data for ATP. In a glovebox, 5 (0.012 g, 0.038 mmol) was suspended in acetonitrile (1 mL). To this stirring suspension was added a 0.10 g/mL solution of (TBA) 2 pA in acetonitrile (0.31 mL, 0.038 mmol). After stirring for 5 min, all of the solid material had dissolved. To this solution was then added diethylamine (0.014 g, 0.19 mmol) in acetonitrile (1 mL). The resulting mixture was stirred for 6 hours, then volatiles were evaporated under reduced pressure, leaving an oily solid. This residue was then removed from the glovebox and dissolved in deionized water (2 mL). The resulting solution was then filtered through an Acrodisc 0.2 µm wwPTFE syringe filter and purified by AX-HPLC according to the procedure in the General Considerations. The fractions containing the product were pooled and lyophilized. The resulting solid was again dissolved in deionized water and lyophilized giving the product as a fluffy white solid (0.013 g, 0.022 mmol, 58% yield). After repeated lyophilizations of the product, the P-N bond was found to undergo hydrolysis, giving ATP as the primary phosphorus containing species. In a glovebox, 5 (0.011 g, 0.036 mmol) was suspended in acetonitrile (1 mL). To this stirring suspension was added a 0.10 g/mL solution of (TBA) 2 pA in acetonitrile (0.30 mL, 0.036 mmol). After stirring for 5 min, all of the solid material had dissolved. Volatiles were then evaporated under reduced pressure, leaving an oily solid. This residue was then dissolved in DMF (1 mL). To this solution was added MgCl 2 (0.0068 g, 0.072 mmol) and a 0.10 g/mL solution of (TBA) 2 pU in DMF (0.35 mL, 0.043 mmol). The resulting solution was stirred for 24 hours. Volatiles were then removed under reduced pressure at 40 °C leaving an oily solid. This residue was then removed from the glovebox and dissolved in deionized water (2 mL). The resulting solution was then filtered through an Acrodisc 0.2 µm wwPTFE syringe filter and purified by AX-HPLC according to the procedure in the General Considerations. The fractions containing the product were pooled and lyophilized. The resulting solid was again dissolved in deionized water and lyophilized giving the product as a fluffy white solid (0.023 g, 0.027 mmol, 74% yield). The experimental characterization date for [NH 4 ] 4 [13] is in good agreement with the literature data for Ap 4 U. In a glovebox, 5 (0.013 g, 0.042 mmol) was suspended in acetonitrile (1 mL). To this stirring suspension was added a 0.10 g/mL solution of (TBA) 3 p 2 A in acetonitrile (0.48 mL, 0.042 mmol). After stirring for 5 min, all of the solid material had dissolved. Volatiles were then evaporated under reduced pressure, leaving an oily solid. This residue was then removed from the glovebox and dissolved in deionized water (2 mL). The resulting solution was then filtered through an Acrodisc 0.2 µm wwPTFE syringe filter and purified by AX-HPLC according to the procedure in the General Considerations. The fractions containing the product were pooled and lyophilized. The resulting solid was again dissolved in deionized water and lyophilized giving the product as a fluffy white solid (0.011 g, 0.017 mmol, 40% yield). 3 Crystallographic Details