THE EFFECTS OF INTERPLAY OF SHIELDING, DIPOLAR COUPLING, AND INDIRECT COUPLING TENSORS IN THE SN-119 NMR-SPECTRA OF SOLID TRIORGANYL TIN FLUORIDES

Tin-119 magic-angle-spinning NMR spectra have been recorded for four solid triorganyl tin fluorides R3SnF (R = methyl, isobutyl, phenyl, and mesityl). The centerbands give evidence of the polymeric nature of the first three compounds, which have fluorine bridges and pentacoordinate tin. The spinning sidebands show the influence of the interplay of shielding, dipolar coupling, and indirect coupling tensors. The theory of such interplay for AX2 spin systems with coaxial tensors of axial symmetry is developed. Its application to the spectra discussed here results in values for shielding tensor components and dipolar coupling constants (including the pseudo-dipolar contribution) and thence (in principle) in estimates for the indirect coupling anisotropy ΔJ. The values of ΔJ may be given unambiguously since the absolute sign of the isotropic indirect coupling is known, but X-ray data on Sn-F distances are not yet known sufficiently well to make full use of the NMR results. Data from spinning-sideband analysis of trimesityltin fluoride are also given. © 1992.