High-field³¹P N.M.R. investigations of the chemical shielding and indirect dipolar coupling of polycrystalline fluorophosphates

Abstract

31p chemical shielding and indirect dipolar coupling data of the polycrystalline fluorophosphates K2PO3F, NazPO3F, BaPO3F and K2P2OsF2 were obtained from broad-line and magic angle sample spinning 31p N.M.R. measurements at 109"3 MHz. The N,M.R. spectra are interpreted in terms of the model established by Vander Hart and Gutowsky. For interpreting the spectrum of KzP2OsF2 the theory was extended to the case of nonaxial 31p chemical shielding tensors.The values of the 31p shielding anisotropy Aa and the asymmetry parameter r/ of the fluorophosphates are explained on the basis of the assumption that in phosphates the character of the chemical bond between phosphorus and bridging oxygen atoms (P-OB bond) is very similar to that between phosphorus and fluorine atoms (P-F bond). In addition, the directions of the principal axes of the shielding tensors with respect to the coordinate system of the fluorophosphate ions are discussed. As a result, further support was obtained for the assumption of the similarity of P-O B and P-F bonds in phosphates.

BiF3 Incorporation in Na/Ba Mixed Network Modifier Fluoride–Phosphate Glasses: Structural Studies by Solid-State NMR and Raman Spectroscopies

“…Likewise, it takes one F species to convert two Q 1 units into two Q 0 units (expressions –), resulting in Q 0 species bonded to zero to two F atoms. While the chemical shift ranges of the non-F-bonded Q 0 , Q 1 , and Q 2 units are well-known, there are only few studies on the 31 P chemical shifts of the potential fluoride-bonded units Q 0 1F , Q 0 2F , and Q 1 1F . − The isotropic chemical shift values reported for Na 2 PO 3 F, which represents a Q 0 1F unit, range from −0.8 ppm (in solution) to +5.9 ppm in the solid state, whereas for barium fluorophosphate, BaPO 3 F, the reported shift is −2.4 ppm. Further insights are obtained from 31 P­{ 19 F} REDOR data, conducted on a representative sample containing 10% BiF 3 , see Figure .…”

Probing halogen bonds with solid-state NMR spectroscopy: observation and interpretation of J(77Se,31P) coupling in halogen-bonded PSe⋯I motifs

“…Simulations also included the direct dipolar coupling between 77 Se and 31 P (R DD = (μ 0 /4π)(γ 77 Se γ 31 P ħ/2π)〈r −3 〉 where r is the distance between the spins), as well as contributions from the anisotropic part of the J tensor (ΔJ). [60][61][62] The 77 Se CS tensor parameters and J coupling values are presented in Table 4 and were obtained by simultaneously modeling the NMR spectra obtained at both MAS frequencies and in both applied magnetic fields. For 2, three magnetic fields were used to model the NMR spectra (see Fig.…”

Solid-state NMR studies of fluorinated diazadiphosphetidines

“…This effect has been described previously for both the PC and PF cases. 23, 24 An observable scalar (isotropic) splitting is essential to distinguish the two manifolds.…”