¹⁹⁹Hg Chemical Shielding Tensor of the Mercurous Ion in Mercurous Nitrate Dihydrate

Using single-crystal NMR, we have measured the full chemical shielding tensor of the Hg2²⁺ ion in mercurous nitrate dihydrate, the first tensor determination of a metallic species involved in a metal-metal bond. The tensor is almost axially symmetric; its unique element is directed approximately along the long axis of the diaquomercurous ion, but it lies closer to the ligand metal axis than the metal-metal bond. The shielding anisotropy of mercury is, as would be expected for a linear mercury compound, quite large (3203 ppm).