Theoretical Search for the Highest Valence States of the Coinage Metals: Roentgenium Heptafluoride May Exist.

We present here a relativistic density functional theory investigation of the penta- and heptavalent states of gold and roentgenium, employing the ZORA (zeroth order regular approximation to the Dirac equation) Hamiltonian, including spin-orbit coupling at the two-component level, and large all-electron relativistic Slater-type quadruple-ζ quadruple polarization (ZORA-STO-QZ4P) basis sets. Unsurprisingly, our calculations confirm the stability of the experimentally known complexes AuF6- and Au2F10 with respect to decomposition to trivalent Au products and F2. The calculations also predict that RgF6- and Rg2F10 should be even more stable with respect to an analogous decomposition pathway. Like an earlier DFT study ( Inorg. Chem. 2007, 46 (13), 5338-5342), our calculations rule out the true heptavalent Au complex AuF7 as a stable species, preferring instead a Cs AuF5···F2 formulation. Remarkably, our calculations confirm a D5 h pentagonal-bipyramidal structure of RgF7 as the global minimum, at an energy of approximately half an electron volt below the RgF5···F2 form.