Sensitivity of 3He NMR Parameters to the Proximity of Heterocyclic Rings. The Helium-Furan Dimer

The potential of the NMR technique in probing the interaction between a noble gas atom (used as a spectroscopic probe) and five-membered heterocyclic systems was theoretically studied. Selected He-3 NMR parameters of the free noble gas atom and its dimer were calculated using density functional theory with three functionals (M06-2X, CAM-B3LYP, and APFD), combined with dedicated polarization-consistent basis sets, and critically compared with theoretical high level calculations from the literature. The change of isotropic nuclear magnetic shielding of the free noble gas atom in the presence of furan (He-3 placed above the middle of the ring and used as NMR probe) increased with its proximity to the heterocyclic ring.