Covalent bonds in α-SnF2 monitored by J-couplings in solid-state NMR spectra

Overview & Synopsis

The stable ambient-temperature phase of tin(II) fluoride, α-SnF2, has been studied by 19F and 119Sn magic-angle spinning (MAS) NMR spectroscopy. A large chemical shift anisotropy (CSA) is observed in the spectra of both nuclides, which is indicative of the presence of stereochemically active lone electron pair on Sn. Symmetric satellite lines with low intensity have been detected in the 119Sn MAS spectra acquired under 19F decoupling, and are assigned to indirect J-couplings between the magnetically active Sn isotopes. The detection of J-couplings is evidence for the existence of genuine covalent bonds in α-SnF2, a fact which has been deduced before from X-ray crystallography, which revealed the presence of Sn--F distances smaller than the sum of the respective ionic radii.