Effects of Intermolecular Interactions on ³³S Magnetic Shielding in Gaseous SF₆

Density-dependent 33 S magnetic shielding has been measured for the first time. For pure gaseous SF 6 and its binary mixtures with Xe, CO 2 and NH 3 at 298 K, an increase in density linearly decreases the 33 S shielding constant of SF 6 . This permits one to separate quantitatively the shielding contributions due to intermolecular interactions and the shielding parameter of an isolated SF 6 molecule. Spin−spin coupling in SF 6 ( 1 J SF ) has also been measured but only for gaseous samples of high densities. It was observed that the 1 J SF coupling constant increases for more dense samples and that the increase is even more pronounced in liquid solutions. All of the new results can be used for an improved verification of ab initio calculations of sulfur shielding and spin−spin coupling in the SF 6 molecule because the new 33 S NMR measurements reveal the magnitudes of appropriate intermolecular effects.