The chemistry of the superheavy elements. II. The stability of high oxidation states in group 11 elements: Relativistic coupled cluster calculations for the di-, tetra- and hexafluoro metallates of Cu, Ag, Au, and element 111

The stability of the high oxidation states +3 and +5 in Group 11 fluorides is studied by relativistic Mo/ller–Plesset (MP) and coupled cluster methods. Higher metal oxidation states are stabilized by relativistic effects. As a result, the hexafluoro complex of the Group 11 element with nuclear charge 111 and oxidation state +5 is the most stable compared to the other congeners. The results also suggest that AgF6− is thermodynamically stable and, therefore, it might be feasable to synthesize this compound. For the copper fluorides we observe very large oscillations in the Mo/ller–Plesset series up to the fourth order. Nonrelativistic calculations lead to the expected trend in the metal–fluorine bond distances for the MF2− compounds, CuF2−<AgF2−<AuF2−<(111)F2−. However, relativistic effects change this trend to CuF2−<AuF2−<(111)F2−<AgF2−. Vibrational frequencies are predicted for all compounds. Where experimental data are available, they generally agree very well with our calculated results.