Table 3.

Intrinsic ³¹P NMR chemical shifts of ${\text{P}}_3{\text{O}}_{10-n}{\left(\text{NH}\right)}_n^{5-}$ (n = 0, 2) anions^a determined by the pH profiles of ³¹P NMR chemical shifts^b of the anions in aqueous solutions^c, t = 25.0 ± 1.0 °C, I = 1.0 mol·L⁻¹ (NaNO₃)

	${\text{P}}_3{\text{O}}_{10}^{5-}$ End	${\text{P}}_3{\text{O}}_{10}^{5-}$ Mid	${\text{P}}_3{\text{O}}_8{\left(\text{NH}\right)}_2^{5-}$ End	${\text{P}}_3{\text{O}}_8{\left(\text{NH}\right)}_2^{5-}$ Mid
δ 5−L/ppm	−4.39 (<0.01)	−18.71 (<0.01)	1.53 (0.01)	1.69 (0.02)
δ 4−HL/ppm	−7.25 (<0.01)	−20.94 (<0.01)	0.53 (0.01)	−1.19 (0.02)
δ 3−H2L/ppm	−9.72 (<0.01)	−21.88 (<0.01)	0.17 (0.01)	−3.16 (0.01)
δ 2−H3L/ppm	−10.43 (<0.01)	−23.05 (<0.01)	0.22 (0.01)	−3.01 (0.05)
δ −H4L/ppm	–d	–d	–e	−0.30 (0.03)

^aValues in parentheses indicate standard deviations derived from the nonlinear least-squares approximation

^bReferred to external 85 % H₃PO₄

^cIn the absence of D₂O for field-frequency locking

^dCorresponding species were scarcely formed

^eThis value could not be determined because of the slight change of the ³¹P NMR chemical shift due to the protonation of the anion