NMR studies of³¹P, ¹H spin pairs in solid tin(II) phosphite and tin(II) hydrogen phosphate

NMR crystallography of molecular organics

“…For strong dipolar couplings between unlike (hetero) nuclei, this recoupling can be easily and robustly achieved by the classic cross-polarisation (CP) technique used to transfer magnetisation from an abundant spin, typically 1 H, to a dilute isotope, such as 13 C. For example, the distances between Sn and H in SnHPO 3 and SnHPO 4 have been measured to pm precision (1.42 vs. 2.05 Å respectively) using the 119 Sn/ 1 H dipolar couplings obtained from the build-up of 119 Sn magnetisation under CP from 1 H [31]. CP build-up curves have been similarly used to measure N-H distances in NH 2 groups (sample enriched in 15 N) [32]; the initial oscillations of the build-up curves were well fitted by simulations of an isolated NH 2 spin system, resulting in much more accurate and consistent N-H distances, 1.055(7) Å, than observed in the diffraction study (0.87-1.01 Å).…”

“…But this very sensitivity to multiple distances provided good discriminating power. Note that achieving good quantitative agreement between experimental and simulated data required accounting for the significant chemical shift anisotropy (CSA) of 31 P, and inhomogeneity of the radio-frequency field. With these precautions, it was clearly possible to discriminate between correct and incorrect candidate structures generated by software, FOX, more typically used to generate structures for fitting PXRD data.…”

“…In a rare example of a quantitative treatment of static disorder, 31 P lineshapes were used to characterise static disorder in a biphosphinoamine [376]. The spectra were assigned using DQ/SQ correlation experiments and synthetic 2D spectra derived from calculated shifts.…”

The effectiveness of 1H decoupling in the 13C MAS NMR of paramagnetic solids: An experimental case study incorporating copper(II) amino acid complexes

“…The residual linewidths observed under CW decoupling arise primarily from recoupling of the magnetic shielding anisotropy of the decoupled spins and the heteronuclear dipolar coupling that is no longer averaged by rapid spin-diffusion [45,72,77]. For isolated spin-pairs, this recoupling results in a broad doublet [72,82], the splitting of which, in Hz, depends directly on the magnetic shielding anisotropy of the decoupled spin and hence the magnetic field strength [76], but inversely with the decoupling strength [72,82]. For paramagnetic organic solids, the presence of unpaired electrons indirectly results in an increase in the magnitude of the cross-terms arising from the 13 C-1 H dipolar coupling and 1 H magnetic shielding anisotropy, and thus the residual linewidths observed under CW decoupling.…”

Solid state NMR spectroscopy

“…831 A 31 P NMR study has been reported for spin-dynamics in Si:P. 832 1 H and 31 P spin pairs in solid SnHPO 3 and SnHPO 4 gave information on spindynamics in these systems. 833 The 1 H and 31 P NMR spectra of CsH 2 PO 4 above the superionic phase transition at 502 K show the presence of dynamically disordered PO 4 units. 834 Solid-state 31 P NMR spectra were used to probe conformational equilibria for Pd 2 XY(dppm) 2 , where X = Y = Cl, Br, I; X = Cl, Y = SnCl 3 .…”