Intermetallic compounds of the heaviest elements: The electronic structure and bonding of dimers of element 112 and its homolog Hg

Fully relativistic (four-component) density-functional calculations were performed for the element 112 dimers (112)X (X = Pd, Cu, Ag and Au) and those of its lighter homolog, Hg. A relatively small decrease of about 15-20 kJ/mol in bonding was found from the HgX to (112)X compounds. Respectively, the bond lengths were increased by 0.06 Å on the average. The Mulliken population analysis has shown this effect to be a result of a decreasing contribution of the relativistically stabilized 7s-AO of element 112 to bonding. The following trend in the binding energies was predicted for (112)X as a function of X: Pd > Cu > Au > Ag, exactly as the trend obtained experimentally for adsorption of Hg on the corresponding metal surfaces.