Solid-State ¹⁵N and ¹⁷O NMR Studies of S-Nitrosothiols

We report a solid-state ¹⁵N and ¹⁷O NMR study of two representative S-nitrosothiols (RSNO): S-nitroso N-acetylpenicillamine (SNAP) and S-nitrosoglutathione (GSNO). The ¹⁵N and ¹⁷O NMR tensors are experimentally determined for the first time for this important class of nitric-oxide (NO)-related compounds. The observed NMR characteristics for RSNO include large ¹⁵N and ¹⁷O chemical shift anisotropies and large ¹⁷O quadrupole coupling constants. Quantum chemical calculations are also performed for the ¹⁵N and ¹⁷O NMR tensors in two simple RSNO models: t-BuSNO and MeSNO. On the basis of computational results, we have identified the molecular orbitals that are responsible for the observed large chemical shift anisotropies in RSNO compounds.