Covalent Bonds in α‐SnF₂ Monitored by J‐Couplings in Solid‐State NMR Spectra

Abstract

The stable ambient‐temperature phase of tin(II) fluoride, α‐SnF2, was 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 tin. 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 tin isotopes. The detection of J‐couplings is evidence for the existence of genuine covalent bonds in α‐SnF2, a fact which was deduced before from X‐ray crystallography, which revealed the presence of Sn–F distances smaller than the sum of the respective ionic radii.

Experimental and Computational Insights into the Stabilization of Low-Valent Main Group Elements Using Crown Ethers and Related Ligands

“…The much larger Ω measured for the cation in 6 dwarfs those for all of the triflate complexes, again demonstrating that there are fundamental differences between the seemingly analogous chloride and triflate complexes. In this regard, it is well-known from 119 Sn SSNMR studies of Sn­(II) complexes − and 207 Pb SSNMR studies of Pb­(II) complexes, − that as the p-orbital character of the HOMO metal centered “lone pair” increases, Ω is usually observed to increase as well. Among the triflate complexes, 3 – 5 have the most positive values of δ iso , larger values of Ω, and possess the least spherically symmetric Sn coordination environments.…”

Dynamic Lone Pairs and Fluoride-Ion Disorder in Cubic-BaSnF4

“…The first of these peaks has a δ iso value close to that of BaF 2 (−14.2 ppm), where fluoride ions occupy Ba 4 -coordinated tetrahedral sites. The second peak aligns with the average δ iso value of α-SnF 2 (−46 ppm), in which fluorine is triply coordinated with short Sn–F distances . Based on these comparisons, we assign these features at −14 and −45 ppm to broadly Ba-rich and Sn-rich fluorine environments, respectively.…”

Mixed Tin Valence in the Tin(II/IV)‐Nitridophosphate Sn3P8N16

“…By comparing spectra at different spinning speeds (Figure S4), the isotropic resonance of the Sn II species can be determined to be at δ ≈ −730 ppm. We also note that the strong resonance line in Figure 6 exhibits symmetrical low shoulders, which are typical for Sn spectra affected by indirect couplings [57–59] . In Sn 3 P 8 N 16 , the predominant coupling partners are 14 N (99.6 % natural abundance) via one bond and 31 P (100 % n.…”

“…We also note that the strong resonance line in Figure 6 exhibits symmetrical low shoulders, which are typical for Sn spectra affected by indirect couplings. [57][58][59] In Sn 3 P 8 N 16 , the predominant coupling partners are 14 N (99.6 % natural abundance) via one bond and 31 P (100 % n. a.)…”