High-field solid-state 35Cl NMR in selenium(IV) and tellurium(IV) hexachlorides

Abstract

We report solid-state 35 Cl NMR spectra in three hexachlorides, (NH 4 ) 2 SeCl 6 , (NH 4 ) 2 TeCl 6 and Rb 2 TeCl 6 .The C Q ( 35 Cl) quadrupole coupling constants in the three compounds were found to be 41.4±0.1 MHz, 30.3±0.1 MHz and 30.3±0.1 MHz, respectively, some of the largest C Q ( 35 Cl) quadrupole coupling constants ever measured in polycrystalline powdered solids directly via 35 Cl NMR spectroscopy. The 35 Cl EFG tensors are axial in all three cases reflecting the C 4v point group symmetry of the chlorine sites. 35 Cl NMR experiments in these compounds were only made possible by employing the WURST-QCPMG pulse sequence in the ultrahigh magnetic field of 21.1 T. 35 Cl NMR results agree with the earlier reported 35 Cl NQR values and with the complementary plane-wave DFT calculations. The origin of the very large C Q ( 35 Cl) quadrupole coupling constants in these and other main-group chlorides lies in the covalent-type chlorine bonding. The ionic bonding in the ionic chlorides results in significantly reduced C Q ( 35 Cl) values as illustrated with triphenyltellurium chloride Ph 3 TeCl. The high sensitivity of 35 Cl NMR to the chlorine coordination environment is demonstrated using tetrachlorohydroxotellurate hydrate K[TeCl 4 (OH)]⋅0.5H 2 O as an example. 125 Te MAS NMR experiments were performed for tellurium compounds to support 35 Cl NMR findings.

Recent progress in solid‐state nuclear magnetic resonance of half‐integer spin low‐γ quadrupolar nuclei applied to inorganic materials

“…It was clear that with spectral widths of up to 2.5 MHz needing to be recorded even at 21.1 T, this was only really possible in a practical time by employing WURST-QCPMG. [167] Wide lines typically require a VOCS approach as shown for InCl 3 .xH 2 O (Figure 10C). [39] Apatites (Ca 5 (PO 4 ) 3 X, where X = F, OH, or Cl) are undoubtedly some of the most interesting inorganic materials, both from the fundamental structural perspective, but also their importance for a very wide range of scientific disciplines.…”

Chlorination of Hydrogenated Silicon Nanosheets Revealed by Solid-State Nuclear Magnetic Resonance Spectroscopy

“…35 Cl has a nuclear spin of 3/2, a natural isotopic abundance of 75%, and a gyromagnetic ratio close to that of 15 N, making it appealing for solid-state NMR experiments. However, acquisition of 35 Cl solid-state NMR spectra is often challenging because quadrupolar signal broadening results in central-transition (CT) NMR spectra that are typically megahertz broad, especially for terminal, covalently bonded Cl atoms. − 35 Cl solid-state NMR spectra are generally obtained under static conditions with Car–Purcell–Meiboom–Gill (CPMG) and frequency-stepped acquisition techniques. − Unfortunately, static 35 Cl solid-state NMR experiments often suffer from poor sensitivity and resolution. Here, we show that 1 H­{ 35 Cl} and 29 Si­{ 35 Cl} Resonance-Echo Saturation-Pulse DOuble-Resonance (RESPDOR) NMR experiments can be used to directly confirm the presence of chlorinated Si atoms in Si-NS.…”

Chlorination of Hydrogenated Silicon Nanosheets Revealed by 1H{35Cl} and 29Si{35Cl} Solid-State NMR Spectroscopy

“…23-36 35 Cl solid-state NMR spectra are generally obtained under static conditions with Car-Purcell-Meiboom-Gill (CPMG) and frequency-stepped acquisition techniques. [23][24][25][26][27][28][29][30][31][32][33][34][35][36] Unfortunately, static 35 Cl solid-state NMR experiments often suffer from poor sensitivity and resolution. Here, we show 1 H{ 35 Cl} and 29 Si{ 35 Cl} Resonance-Echo Saturation-Pulse DOuble-Resonance (RESPDOR) NMR experiments to directly confirm the presence of chlorinated Si atoms in Si-NS.…”