Double-Quantum Filtered MAS NMR in the Presence of Chemical Shielding Anisotropies and Direct Dipolar and JCouplings

✍ Scribed by Matthias Bechmann; Xavier Helluy; Claire Marichal; Angelika Sebald

• Publisher: Elsevier Science
• Year: 2002
• Tongue: English
• Weight: 297 KB
• Volume: 21
• Category: Article
• ISSN: 0926-2040
• DOI: 10.1006/snmr.2001.0042

✦ Synopsis

Double-quantum filtered MAS NMR spectra of an isolated homonuclear spin-1/2 pair are considered, at and away from rotational resonance conditions. The pulse sequence used is the solid-state NMR equivalent of double-quantum filtered COSY, known from solution-state NMR. The 119Sn spin pair in [(chex3Sn)2S] is characterized by a difference in isotropic chemical shielding smaller than the two chemical shielding anisotropies and by direct dipolar and isotropic J-coupling constants of similar magnitudes. At rotational resonance, one-dimensional double-quantum filtered 119Sn lineshapes yield the relative orientation of the two 119Sn chemical shielding tensors. Good double-quantum filtration efficiencies are found at and away from rotational resonance conditions, despite the presence of large chemical shielding anisotropies. Numerical simulations illustrate the interplay of the direct dipolar and J-coupling pathways and identify the latter as the main pathway even at rotational resonance conditions.