Mercury fulminate: ONC-Hg-CNO or CNO-Hg-ONC - a DFT study

The molecular structure of mercury fulminate was investigated at B3LYP level of theory using a large and a small core scalar relativistic pseudopotential for mercury. In accord with recent X-ray studies the connectivity in mercury fulminate is ONC-Hg-CNO and not CNO-Hg-ONC as previously predicted. Whereas mercury fulminate, ONC-Hg-CNO, has a C2 structure in the solid state with an Hg-C-N angle of 169°, as an isolated molecule it is perfectly linear and possesses D∞h symmetry. The VB structure which corresponds best to the calculated and observed bond lengths belongs to the type of increased-valence VB structures.